Korea Electric Power (KEP) 20-F 30 Apr 18 2017 FY Annual report (foreign) Financial data

Document And Entity Information

Document And Entity Information	12 Months Ended
	Dec. 31, 2017shares
Document and entity information [Abstract]
Entity registrant name	KOREA ELECTRIC POWER CORP
Trading Symbol	KEP
Entity central index key	887,225
Document type	20-F
Document period end date	Dec. 31, 2017
Amendment flag	false
Document fiscal year focus	2,017
Document fiscal period focus	FY
Current fiscal year end date	--12-31
Entity well-known seasoned issuer	Yes
Entity voluntary filers	No
Entity current reporting status	Yes
Entity filer category	Large Accelerated Filer
Entity common stock, shares outstanding	641,964,077

Consolidated Statements Of Fina

Consolidated Statements Of Financial Position - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Current assets [Abstract]
Cash and cash equivalents (Notes 5,6,7 and 45)		₩ 2,369,739	₩ 3,051,353
Current financial assets, net (Notes 5,10,11,12 and 45)		1,958,357	2,671,989
Trade and other receivables, net (Notes 5,8,14,20,45,46 and 47)		7,928,972	7,788,876
Inventories, net (Notes 13)		6,002,086	5,479,443
Income tax refund receivables (Notes 41)		100,590	19,163
Current non-financial assets (Notes 15)		753,992	631,860
Assets held for sale (Notes 42)		27,971	65,842
Total current assets		19,141,707	19,708,526
Non-current assets [Abstract]
Non-current financial assets, net (Notes 5,6,9,10,11,12 and 45)		2,038,913	2,657,494
Non-current trade and other receivables, net (Notes 5,8,14,45,46 and 47)		1,754,797	1,903,515
Property, plant and equipment, net (Notes 18,27 and 49)		150,882,414	145,743,056
Investment properties, net (Notes 19 and 27)		284,714	353,680
Goodwill (Notes 16)		2,582	2,582
Intangible assets other than goodwill, net (Notes 21,27 and 46)		1,187,121	980,821
Investments in associates (Notes 4 and 17)		3,837,421	4,092,252
Investments in joint ventures (Notes 4 and 17)		1,493,275	1,418,196
Deferred tax assets (Notes 41)		919,153	795,131
Non-current non-financial assets (Notes 15)		246,818	181,789
Total non-current assets		162,647,208	158,128,516
Total Assets (Notes 4)		181,788,915	177,837,042
Current liabilities [Abstract]
Trade and other payables, net (Note 5,22,24,45 and 47)		5,999,521	5,585,411
Current financial liabilities, net (Note 5,11,23,45 and 47)		9,194,552	8,942,329
Income tax payables (Note 41)		508,402	1,843,288
Current non-financial liabilities (Note 20,28 and 29)		5,584,308	6,368,210
Current provisions (Note 26 and 45)		2,137,498	1,999,988
Total current liabilities		23,424,281	24,739,226
Non-current liabilities [Abstract]
Non-current trade and other payables, net (Note 5,22,24,45 and 47)		3,223,480	3,558,175
Non-current financial liabilities, net (Note 5,11,23,45 and 47)		45,980,899	44,835,562
Non-current non-financial liabilities (Note 28 and 29)		8,072,434	7,591,605
Employee benefits liabilities, net (Note 25 and 45)		1,483,069	1,686,258
Deferred tax liabilities (Note 41)		10,415,397	8,948,520
Non-current provisions (Note 26 and 45)		16,224,714	13,427,151
Total non-current liabilities		85,399,993	80,047,271
Total liabilities (Note 4)		108,824,274	104,786,497
Equity [Abstract]
Contributed capital (Note 1,30 and 45)		4,053,578	4,053,578
Share capital		3,209,820	3,209,820
Share premium		843,758	843,758
Retained earnings (Note 31)		53,370,558	53,173,871
Legal reserves	[1]	1,604,910	1,604,910
Voluntary reserves		34,833,844	31,847,275
Unappropriated retained earnings		16,931,804	19,721,686
Other components of equity (Note 34)		14,257,309	14,496,244
Other capital surplus		1,233,793	1,235,146
Accumulated other comprehensive loss		(271,457)	(33,875)
Other equity		13,294,973	13,294,973
Equity attributable to owners of the controlling company		71,681,445	71,723,693
Non-controlling interests (Note 16 and 33)		1,283,196	1,326,852
Total equity		72,964,641	73,050,545
Total equity and liabilities		₩ 181,788,915	₩ 177,837,042
[1]	The KEPCO Act requires KEPCO to appropriate a legal reserve equal to at least 20 percent of net income for each accounting period until the reserve equals 50 percent of KEPCO’s common stock. The legal reserve is not available for cash dividends; however, this reserve may be credited to paid-in capital or offset against accumulated deficit by the resolution of the shareholders.

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of comprehensive income [Abstract]
Sales (Notes 4,35,45 and 47)	₩ 59,335,889	₩ 59,763,087	₩ 58,581,727
Sales of goods	55,772,548	55,379,487	54,367,036
Sales of construction services (Note 20)	3,212,184	4,026,857	3,761,204
Sales of services	351,157	356,743	453,487
Cost of sales (Notes 13,25,43 and 47)	(52,098,855)	(45,549,553)	(45,457,729)
Cost of sales of goods	(48,454,036)	(41,237,372)	(41,348,917)
Cost of sales of construction services	(3,047,396)	(3,755,144)	(3,563,120)
Cost of sales of services	(597,423)	(557,037)	(545,692)
Gross profit	7,237,034	14,213,534	13,123,998
Selling and administrative expenses (Note 25,36,43 and 47)	(2,762,855)	(2,639,232)	(2,153,261)
Other income (Note 37)	869,118	840,184	808,214
Other expenses (Note 37)	(180,055)	(188,624)	(108,848)
Other gains, net (Note 38)	156,627	70,498	8,610,773
Operating profit (Note 4)	5,319,869	12,296,360	20,280,876
Finance income (Note 5,11 and 39)	1,530,618	791,543	1,182,988
Finance expenses (Note 5,11 and 40)	(3,127,952)	(2,437,087)	(3,015,457)
Profit (loss) related to associates, joint ventures and subsidiaries (Note 4 and 17)	(108,317)	(137,348)	207,379
Share in profit of associates and joint ventures	241,537	224,435	280,794
Gain on disposal of investments in associates and joint ventures	609	52	4,731
Gain on disposal of investments in subsidiaries (Note 16)	0	0	8,376
Share in loss of associates and joint ventures	(323,225)	(243,361)	(86,522)
Loss on disposal of investments in associates and joint ventures	0	(2,935)	0
Impairment loss on investments in associates and joint ventures (Note 17)	(27,238)	(115,539)	0
Profit before income tax	3,614,218	10,513,468	18,655,786
Income tax expense (Note 41)	(2,172,824)	(3,365,141)	(5,239,413)
Profit for the period	1,441,394	7,148,327	13,416,373
Other comprehensive income (loss) (Note 5,11,25,31 and 34)	(94,716)	(2,302)	34,006
Items that will not be reclassified subsequently to profit or loss: [Abstract]
Remeasurements of defined benefit liability, net of tax (Note 25 and 31)	170,337	(75,926)	(87,861)
Share in other comprehensive loss of associates and joint ventures, net of tax (Note 31)	10,067	(2,515)	(283)
Items that are or may be reclassified subsequently to profit or loss: [Abstract]
Net change in the unrealized fair value of available-for-sale financial assets, net of tax (Note 34)	(7,098)	61,279	9,648
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax (Note 5,11 and 34)	20,868	28,414	4,409
Foreign currency translation of foreign operations, net of tax (Note 34)	(134,196)	41,360	18,535
Share in other comprehensive income (loss) of associates and joint ventures, net of tax (Note 34)	(154,694)	(54,914)	89,558
Total comprehensive income for the period	1,346,678	7,146,025	13,450,379
Profit or loss attributable to: [Abstract]
Owners of the controlling company (Note 44)	1,298,720	7,048,581	13,289,127
Non-controlling interests	142,674	99,746	127,246
Profit for the period	1,441,394	7,148,327	13,416,373
Total comprehensive income attributable to: [Abstract]
Owners of the controlling company	1,230,194	7,041,557	13,308,132
Non-controlling interests	116,484	104,468	142,247
Other comprehensive income (loss)	₩ 1,346,678	₩ 7,146,025	₩ 13,450,379
Earnings per share (in won) (Note 44) [Abstract]
Basic and diluted earnings per share	₩ 2,023	₩ 10,980	₩ 20,701

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Equity - KRW (₩) ₩ in Millions	Total	Equity attributable to owners of parent [Member]	Contributed capital [Member]	Retained earnings [Member]	Other Components Of Equity [Member]	Non-controlling interests [Member]
Balance at Dec. 31, 2014	₩ 54,825,010	₩ 53,601,331	₩ 4,053,578	₩ 35,303,647	₩ 14,244,106	₩ 1,223,679
Comprehensive income [Abstract]
Profit for the period	13,416,373	13,289,127	0	13,289,127	0	127,246
Items that will not be reclassified subsequently to profit or loss: [Abstract]
Remeasurements of defined benefit liability, net of tax	(87,861)	(84,271)	0	(84,271)	0	(3,590)
Share in other comprehensive income (loss) of associates and joint ventures, net of tax	(283)	(280)	0	(280)	0	(3)
Items that are or may be reclassified subsequently to profit or loss: [Abstract]
Net change in the unrealized fair value of available-for-sale financial assets, net of tax	9,648	9,744	0	0	9,744	(96)
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	4,409	3,157	0	0	3,157	1,252
Foreign currency translation of foreign operations, net of tax	18,535	1,179	0	0	1,179	17,356
Share in other comprehensive income (loss) of associates and joint ventures, net of tax	89,558	89,476	0	0	89,476	82
Dividends paid	(407,053)	(320,982)	0	(320,982)	0	(86,071)
Issuance of share capital by subsidiaries	14,865	2,536	0	0	2,536	12,329
Equity transaction within consolidation scope – other than issuance of share capital	53,212	44,166	0	0	44,166	9,046
Disposal of treasury stocks	22,513	(716)	0	0	(716)	23,229
Changes in consolidation scope	(16,455)	0	0	0	0	(16,455)
Dividends paid (hybrid bond)	4	0	0	0	0	4
Repayment of hybrid securities	0	0	0	0	0	0
Other changes in equity		0	0	0	0	0
Balance at Dec. 31, 2015	67,942,475	66,634,467	4,053,578	48,187,241	14,393,648	1,308,008
Comprehensive income [Abstract]
Profit for the period	7,148,327	7,048,581	0	7,048,581	0	99,746
Items that will not be reclassified subsequently to profit or loss: [Abstract]
Remeasurements of defined benefit liability, net of tax	(75,926)	(69,330)	0	(69,330)	0	(6,596)
Share in other comprehensive income (loss) of associates and joint ventures, net of tax	(2,515)	(2,532)	0	(2,532)	0	17
Items that are or may be reclassified subsequently to profit or loss: [Abstract]
Net change in the unrealized fair value of available-for-sale financial assets, net of tax	61,279	61,275	0	0	61,275	4
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	28,414	27,075	0	0	27,075	1,339
Foreign currency translation of foreign operations, net of tax	41,360	31,406	0	0	31,406	9,954
Share in other comprehensive income (loss) of associates and joint ventures, net of tax	(54,914)	(54,918)	0	0	(54,918)	4
Dividends paid	(2,090,071)	(1,990,089)	0	(1,990,089)	0	(99,982)
Issuance of share capital by subsidiaries	16,559	1,750	0	0	1,750	14,809
Equity transaction within consolidation scope – other than issuance of share capital	48,307	36,008	0	0	36,008	12,299
Disposal of treasury stocks	0	0	0	0	0	0
Changes in consolidation scope	3,705	0	0	0	0	3,705
Dividends paid (hybrid bond)	(16,455)	0	0	0	0	(16,455)
Repayment of hybrid securities	0	0	0	0	0	0
Other changes in equity		0	0	0	0	0
Balance at Dec. 31, 2016	73,050,545	71,723,693	4,053,578	53,173,871	14,496,244	1,326,852
Comprehensive income [Abstract]
Profit for the period	1,441,394	1,298,720	0	1,298,720	0	142,674
Items that will not be reclassified subsequently to profit or loss: [Abstract]
Remeasurements of defined benefit liability, net of tax	170,337	158,991	0	158,991	0	11,346
Share in other comprehensive income (loss) of associates and joint ventures, net of tax	10,067	10,065	0	10,065	0	2
Items that are or may be reclassified subsequently to profit or loss: [Abstract]
Net change in the unrealized fair value of available-for-sale financial assets, net of tax	(7,098)	(7,102)	0	0	(7,102)	4
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	20,868	19,614	0	0	19,614	1,254
Foreign currency translation of foreign operations, net of tax	(134,196)	(95,103)	0	0	(95,103)	(39,093)
Share in other comprehensive income (loss) of associates and joint ventures, net of tax	(154,694)	(154,991)	0	0	(154,991)	297
Dividends paid	(1,341,341)	(1,271,089)	0	(1,271,089)	0	(70,252)
Issuance of share capital by subsidiaries	17,003	(1,378)	0	0	(1,378)	18,381
Equity transaction within consolidation scope – other than issuance of share capital	0	0	0	0	0	0
Disposal of treasury stocks	0	0	0	0	0	0
Changes in consolidation scope	7,337	0	0	0	0	7,337
Dividends paid (hybrid bond)	(15,856)	0	0	0	0	(15,856)
Repayment of hybrid securities	(99,750)	0	0	0	0	(99,750)
Other changes in equity	25	25	0	0	25	0
Balance at Dec. 31, 2017	₩ 72,964,641	₩ 71,681,445	₩ 4,053,578	₩ 53,370,558	₩ 14,257,309	₩ 1,283,196

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from (used in) operating activities [Abstract]
Profit for the period	₩ 1,441,394	₩ 7,148,327	₩ 13,416,373
Adjustments for: [Abstract]
Income Tax Expense	2,172,824	3,365,141	5,239,413
Depreciation	9,660,039	8,881,273	8,269,118
Amortisation	113,672	79,715	72,266
Employee benefits expense	391,360	373,753	314,692
Bad debt expense	126,326	37,815	18,350
Interest expense	1,789,552	1,752,868	2,015,684
Losses on sale of financial assets	2,343	9	3,008
Losses on disposals of property, plant and equipment	70,514	4,996	1,933
Loss on abandonment of property, plant, and equipment	424,091	426,519	365,056
Impairment loss on property, plant and equipment	51,067	0	30,344
Impairment loss on intangible assets	20	3,945	22
Losses on disposal of intangible assets	183	158	16
Increase to provisions	1,690,120	1,782,732	1,602,724
Loss (gain) on foreign currency translation, net	(902,878)	253,468	617,224
Valuation and transaction loss (gain) on derivative instruments, net	1,043,628	(231,630)	(708,120)
Share in loss (income) of associates and joint ventures, net	81,688	18,926	(194,272)
Gains on disposal of financial assets	(1,130)	(1,482)	(4)
Gains on disposal of property plant, and equipment	(48,316)	(74,035)	(8,637,508)
Gains on disposal of intangible assets	(564)	0	(32)
Gain on disposal of investments in associates and joint ventures	(609)	(52)	(4,731)
Loss on disposal of investments in associates and joint ventures	0	2,935	0
Gain on disposal of investments in subsidiaries	0	0	(8,376)
Impairment loss on investments in associates and joint ventures	27,238	115,539	0
Interest income	(206,143)	(241,778)	(241,585)
Dividends income	(11,477)	(9,446)	(14,069)
Impairment loss on available-for-sale financial assets	2,713	86,703	84,370
Other inflows (outflows) of cash	16,679	66,260	(35,107)
Adjustments for Cash flows from operating activities	16,492,940	16,694,332	8,790,416
Changes in: [Abstract]
Trade receivables	(218,328)	200,529	715,498
Non-trade receivables	(31,807)	(68,322)	(17,102)
Accrued income	577,838	69,151	17,051
Other receivables	(1,271)	10,093	(9,441)
Other current assets	37,576	(259,492)	67,520
Inventories	(1,373,438)	(1,439,545)	(1,190,188)
Other non-current assets	(46,079)	(2,792)	(31,465)
Trade payables	342,126	141,994	(1,577,551)
Non-trade payables	(214,704)	(8,379)	38,223
Accrued expenses	(715,305)	(153,172)	(410,744)
Other payables	292	0	964
Other current liabilities	(126,323)	284,417	870,945
Other non-current liabilities	763,958	809,699	377,617
Investments in associates and joint ventures (dividends received)	106,983	75,407	114,708
Provisions	(1,390,606)	(1,527,129)	(1,033,502)
Payments of employee benefit obligations	(69,489)	(53,477)	(43,100)
Plan assets	(325,080)	(312,125)	(214,449)
Changes in assets and liabilities Cash flows from operating activities	(2,683,657)	(2,233,143)	(2,325,016)
Cash generated from operating activities	15,250,677	21,609,516	19,881,773
Dividends received (available-for-sale financial assets)	10,590	10,294	38,565
Interest paid	(1,886,303)	(2,041,379)	(2,176,040)
Interest received	173,226	240,878	133,875
Income taxes paid	(2,298,296)	(3,298,757)	(935,068)
Net cash flows from operating activities	11,249,894	16,520,552	16,943,105
Cash flows from investing activities [Abstract]
Proceeds from disposals of associates and joint ventures	10,542	46,644	22,058
Acquisition of associates and joint ventures	(206,753)	(113,222)	(116,114)
Proceeds from sales of property, plant and equipment	85,801	207,960	9,843,796
Acquisition of property, plant and equipment	(12,535,958)	(12,028,789)	(14,049,887)
Proceeds from sales of intangible assets	1,072	430	467
Acquisition of intangible assets	(143,887)	(124,422)	(87,946)
Proceeds from disposals of financial assets	5,296,680	10,876,017	242,856
Acquisition of financial assets	(4,786,717)	(8,130,621)	(5,326,151)
Increase in loans	(218,698)	(206,092)	(153,570)
Collection of loans	120,967	117,561	111,714
Increase in deposits	(397,078)	(468,734)	(352,669)
Decrease in deposits	110,383	161,166	185,154
Proceeds from government grants	55,533	32,878	52,696
Net cash inflow (outflow) from changes in consolidation scope	0	3,754	(968)
Other cash inflow (outflow) from investing activities, net	1,414	(20,400)	(145,406)
Net cash flows used in investing activities	(12,606,699)	(9,645,870)	(9,773,970)
Cash flows from financing activities [Abstract]
Proceeds from (Repayment of) short-term borrowings, Net	370,328	(49,604)	(65,355)
Proceeds from long-term borrowings and debt securities	10,098,067	2,302,060	4,178,454
Repayment of long-term borrowings and debt securities	(8,198,882)	(7,750,047)	(8,960,706)
Payment of finance lease liabilities	(122,919)	(118,215)	(110,040)
Settlement of derivative instruments, net	33,434	73,246	73,348
Proceeds on disposal of partial interest in a subsidiary that does not involve loss of control	0	0	67,914
Change in non-controlling interest	23,582	10,538	36,105
Repayment of hybrid bond	(99,750)	0	0
Dividends paid (hybrid bond)	(15,856)	(16,455)	(16,455)
Dividends paid	(1,340,387)	(2,088,429)	(409,884)
Other cash outflow from financing activities, net	(2,023)	(570)	0
Net cash flows from (used in) financing activities	745,594	(7,637,476)	(5,206,619)
Net increase (decrease) in cash and cash equivalents before effect of exchange rate changes	(611,211)	(762,794)	1,962,516
Effect of exchange rate fluctuations on cash held	(70,403)	31,082	24,249
Net increase (decrease) in cash and cash equivalents	(681,614)	(731,712)	1,986,765
Cash and cash equivalents at January 1	3,051,353	3,783,065	1,796,300
Cash and cash equivalents at December 31	₩ 2,369,739	₩ 3,051,353	₩ 3,783,065

Reporting Entity (Description o

Reporting Entity (Description of the controlling company)	12 Months Ended
	Dec. 31, 2017
Reporting Entity (Description of the controlling company) [Abstract]
Reporting Entity (Description of the controlling company)	1. Reporting Entity (Description of the controlling company) Korea Electric Power Corporation (“KEPCO”) was incorporated on January 1, 1982 in accordance with the Korea Electric Power Corporation Act (the “KEPCO Act”) to engage in the generation, transmission and distribution of electricity and development of electric power resources in the Republic of Korea. KEPCO also provides power plant construction services. KEPCO’s stock was listed on the Korea Stock Exchange on August 10, 1989 and KEPCO listed its Depository Receipts (DR) on the New York Stock Exchange on October 27, 1994. KEPCO’s head office is located in Naju, Jeollanam-do. As of December 31, 2017, KEPCO’s share capital amounts to ￦3,209,820 million and KEPCO’s shareholders are as follows: Number of shares Percentage of ownership Government of the Republic of Korea 116,841,794 18.20 % Korea Development Bank 211,235,264 32.90 % Foreign investors 194,050,746 30.23 % Other 119,836,273 18.67 % 641,964,077 100.00 % In accordance with the Restructuring Plan enacted on January 21, 1999 by the Ministry of Trade, Industry and Energy, KEPCO spun off its power generation divisions on April 2, 2001, resulting in the establishment of six power generation subsidiaries.

Basis of Preparation

Basis of Preparation	12 Months Ended
	Dec. 31, 2017
Basis of Preparation [Abstract]
Basis of Preparation	2. Basis of Preparation The consolidated financial statements of Korea Electric Power Corporation and subsidiaries (the “Company”) were authorized for issuance by the Board of Directors on February 23, 2018. (1) Statement of compliance These consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). (2) Basis of measurement These consolidated financial statements have been prepared on the historical cost basis, except for the following material items in the consolidated statements of financial position: • derivative financial instruments are measured at fair value • available-for-sale • liabilities for defined benefit plans are recognized at the net of the total present value of defined benefit obligations less the fair value of plan assets (3) Functional and presentation currency These consolidated financial statements are presented in Korean won (“Won”), which is KEPCO’s functional and presentation currency. (4) Use of estimates and judgments The preparation of the consolidated financial statements in conformity with IFRS requires management to make judgments, estimates and assumptions that affect the application of accounting policies and the reported amounts of assets, liabilities, income and expenses. Actual results may differ from these estimates. Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimates are revised and in any future periods affected. The following are the key assumptions concerning the future, and other key sources of estimation uncertainty at the end of the reporting period, that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year. (i) Unbilled revenue Energy delivered but not metered nor billed are calculated at the reporting date and is estimated based on consumption statistics and selling price estimates. Determination of the unbilled revenues at the end of the reporting period is sensitive to the estimated consumptions and prices based on statistics. Unbilled revenue recognized for the years ended December 31, 2016 and 2017 are ￦1,615,322 million and ￦1,672,385 million, respectively. (ii) Continuing operation of Wolsong Unit 1 nuclear power plant Wolsong Unit 1 nuclear power plant of the Company commenced operations on November 21, 1982 and its 30-year According to the Eighth Basic Plan for Electricity Supply and Demand by the Ministry of Trade, Industry and Energy, Wolsong Unit 1 nuclear power plant is expected to go through a comprehensive evaluation for the feasibility of continuous operation including economic efficiency and acceptability of household and community in 2018. The Korean government plans to refund to the Company for reasonable expenditures incurred in relation to the phase-out Information about critical judgments in applying accounting policies that have the most significant effect on the amounts recognized in the consolidated financial statements is included in the following notes: • Note 17 – Investments in Associates and Joint Ventures • Note 18 – Property, Plant and Equipment • Note 20 – Construction Services Contracts • Note 45 – Risk Management Information about assumptions and estimation uncertainties that have a significant risk of resulting in a material adjustment within the next financial year is included in the following notes: • Note 41 – Income Taxes • Note 25 – Employment Benefits (5) Changes in accounting policies (i) Amendments to IAS 7 ‘Statement of Cash Flows’ The Company has adopted amendments to IAS ‘Statement of Cash Flows’ since January 1, 2017. The amendments require changes in liabilities arising from financing activities to be disclosed. The amendments are not required to provide comparative information for prior periods when applying for the first time. Information about changes in liabilities arising from financing activities is included in note 23 and note 24. (ii) Amendments to IAS 12 ‘Income Taxes’ The Company has adopted amendments to IAS 12 ‘Income Taxes’ since January 2017. The amendments clarify that unrealized losses on fixed-rate debt instruments measured at fair value and measured at cost for tax purposes give rise to a deductible temporary difference regardless of whether the holder expects to recover the carrying amount of the debt instrument by sale or by use and that the estimate of probable future taxable profit may include the recovery of some of assets for more than their carrying amount. When the Company assesses whether there will be sufficient taxable profit, the Company should compare the deductible temporary differences with future taxable profit that excludes tax deductions resulting from the reversal of those deductible temporary differences. The Company believes that there is no significant impact on the Company’s consolidated financial statements and did not retroactively restate the comparative consolidated financial statements for the prior period. (6) New standards and amendments not yet adopted The following new standards, including IFRS 9 ‘Financial Instruments’ and IFRS 15 ‘Revenue from Contracts with Customers’, interpretations and amendments to existing standards have been published but are not mandatory for the Company for annual periods beginning on January 1, 2017, and the Company has not early adopted them. The Company will apply IFRS 9 ‘Financial Instruments’ and IFRS 15 ‘Revenue from Contracts with Customers’ for annual periods beginning on January 1, 2018. The Company has conducted a detailed assessment on adoption of these standards and based on the circumstance and information available when these financial statements were authorized for issuance. (i) IFRS 9 ‘Financial Instruments’ IFRS 9 sets out the requirements for recognizing and measuring financial assets, financial liabilities and certain contracts to buy or sell non-financial The Company will apply the exemption allowing it not to restate the comparative information for prior periods upon adoption of IFRS 9. The Company will retroactively apply the cumulative effect of the adoption of IFRS 9 in retained earnings as of the date of initial application (January 1, 2018). Expected impacts on the consolidated financial statements are categorized as follows: ① Classification and measurement of financial assets IFRS 9 includes a new classification and measurement of financial assets that reflects the business model in which assets are managed and their cash flow characteristics. Under IFRS 9, financial assets are classified into three principal categories; measured at amortized cost, fair value through other comprehensive income (FVOCI) and fair value through profit or loss (FVTPL) based on the business model in which assets are managed and their cash flow characteristics. Under IFRS 9, derivatives embedded in hybrid contracts where the host is a financial asset are not bifurcated. Instead, the hybrid financial instrument as a whole is assessed for classification. The criteria for classification and measurement of financial assets under IFRS 9 are as follows: • A financial asset is measured at amortized cost if it meets both of the following conditions and is not designated as at FVTPL: 1) the asset is held within a business model whose objective is to hold assets to collect contractual cash flows; and 2) the contractual terms of the financial asset give rise on specified dates to cash flows that are solely payments of principal and interest on the principal amount outstanding. • A financial asset is measured at FVOCI if it meets both of the following conditions and is not designated as at FVTPL: 1) the asset is held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets; and 2) the contractual terms of the financial asset give rise on specified dates to cash flow that are solely payments of principal and interest on the principal amount outstanding. On initial recognition of equity investment that is not held for trading, the Company may irrevocably elect to present subsequent changes in fair value in OCI, and will not reclassify(recycle) the those items in OCI to profit or loss subsequently. • A financial asset is measured at FVTPL if the contractual terms of the financial asset give rise to specified dates to cash flows that are not solely payments of principal and interest on the principal amount outstanding, the debt instrument is held within a business model whose objective is to sell the asset, or the equity instruments that are not elected to be designated as measured at FVOCI. As of December 31, 2017, the Company has financial assets at fair value through profit or loss amounting to ￦133,532 million, available-for-sale held-to-maturity Based on the result of the detailed assessment to date, the expected impacts on the Company’s financial assets (excluding derivative instruments) on the date of initial application (January 1, 2018) are as follows: Classification based on IAS 39 Classification based on IFRS 9 Amount based Amount based In millions of won Financial assets at FVTPL FVTPL ￦ 111,512 111,512 Loans and receivables Amortized cost 15,203,663 14,412,339 Loans and receivables FVTPL — 791,324 Available-for-sale FVOCI 699,833 476,941 Available-for-sale FVTPL — 222,892 Held-to-maturity Amortized cost 3,144 3,144 Total financial assets (excluding derivative instruments) ￦ 16,018,152 16,018,152 Upon adoption of IFRS 9, ￦791,324 million of loans and receivables and ￦222,892 million of available-for-sale available-for-sale ② Classification and measurement of financial liabilities Under IFRS 9, the amount of change in the fair value attributable to the changes in the credit risk of the financial liabilities is presented in OCI, not recognized in profit or loss, and the OCI amount will not be reclassified (recycled) to profit or loss. However, if doing so creates or increase an accounting mismatch, the amount of change in the fair value is recognized in profit or loss. The Company did not elect to designate financial liabilities as FVTPL and believes that there is no significant impact on the Company’s consolidated financial statements upon adoption of IFRS 9. ③ Impairment: Financial assets and contract assets IFRS 9 replaces the ‘incurred loss’ model in the existing standard with a forward-looking ‘expected credit loss’ (ECL) model for debt instruments, lease receivables, contractual assets, loan commitments, financial guarantee contracts. Under IFRS 9, impairment losses are likely to be recognized earlier than using the incurred loss model under the existing guidance in IAS 39 as loss allowances will be measured on either of the 12-month Classification Loss allowances Stage 1 Credit risk has not increased significantly since the initial recognition 12-month ECL: ECLs that resulted from possible default events within the 12 months after the reporting date Stage 2 Credit risk has increased significantly since the initial recognition Lifetime ECL: ECL that resulted from all possible default events over the expected life of a financial instrument Stage 3 Credit-impaired Under IFRS 9, an entity shall always measure the loss allowance at an amount equal to lifetime expected credit losses for trade receivables or contract assets that result from transactions that are within the scope of IFRS 15 and that do not contain a significant financing component in accordance with IFRS 15 and if the trade receivables or contract assets include a significant financing component, an entity may choose as its accounting policy to measure the loss allowance at an amount equal to lifetime expected credit losses. As of December 31, 2017, the Company has debt instruments in financial assets measured at amortized cost amounting to ￦15,464,202 million (loans and receivables) and has recognized loss allowances of ￦260,539 million. Under adoption of IFRS 9, the Company plans to elect to measure the loss allowance at an amount equal to lifetime expected credit losses for trade receivables, contract assets and lease receivables that include a significant financing component. Based on the result of the detailed assessment to date, the expected impacts on the Company’s loss allowances on the date of initial application (January 1, 2018) are as follows: Type Amount based on IAS 39 (A) Amount based on IFRS 9 (B) Increase (decrease) (B-A) In millions of won Trade and other receivables ￦ 251,591 258,360 6,769 Other financial assets 8,948 8,948 — Total ￦ 260,539 267,308 6,769 ④ Hedge accounting When initially applying IFRS 9, an entity may elect as its accounting policy to continue to apply the hedge accounting requirements of IAS 39. The Company plans to elect to continue apply the hedge accounting requirements of IAS 39. As of December 31, 2017, the Company has asset and liabilities designated as hedged items amounting to ￦10,606 million and ￦277,130 million, respectively. (ii) IFRS 15 ‘Revenue from Contracts with Customers’ IFRS 15 sets out a comprehensive framework for determining whether revenue is recognized, the extent of revenue recognized, and when revenue is recognized. It replaces existing revenue recognition guidance, including IAS 18 ‘Revenue’, IAS 11 ‘Construction Contracts’, SIC-31 The Company will retrospectively apply and recognize the cumulative effect of the adoption of IFRS 15 at the date of initial application (January 1, 2018) and has determined to retrospectively apply to only those contracts that were not completed as of the date of initial application (January 1, 2018). Accordingly, the Company will not restate the comparative periods. Existing IFRS standards and interpretations including IAS 18 provide revenue recognition guidance by transaction types such as sales of goods, rendering of services, interest income, royalty income, dividend income and construction revenue; however, under the new standard, IFRS 15, the five-step approach (Step 1: Identify the contract(s) with a customer, Step 2: Identify the performance obligations in the contract, Step 3: Determine the transaction price, Step 4: Allocate the transaction price to the performance obligations in the contract, Step 5: Recognize revenue when the entity satisfied a performance obligation) is applied for all types of contracts or agreements. Expected impacts on the consolidated financial statements are categorized as follows: ① Identify the performance obligations in the contract The Company is engaged in the generation, transmission and distribution of electricity and development of electric power resources, and electricity sales revenue accounts for 91.3% of consolidated revenue for the year ended December 31, 2017. Under IFRS 15, supplying electricity is a series of distinct goods or services identified as a single performance obligation. The Company is also engaged in contracts with customers for transmission and distribution, provision of power generation byproducts, EPC business, O&M, etc. that are identified as different performance obligations for each contract. Based on the result of the detailed assessment to date, the Company believes that the impact of identifying separate the performance obligations in the contract on the Company’s revenue is not significant. ② Variable consideration The Company may be subject to a variation of consideration paid by the customer due to the progressive electricity billing system, discounts on electricity bills for policy purposes, penalties and delinquent payment, etc. In applying IFRS 15, the Company estimates an amount of variable consideration by using the expected value method that the Company expects to better predict the amount of consideration to which it will be entitled, and includes in the transaction price some or all of an amount of variable consideration only to the extent that it is highly probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Based on the result of the detailed assessment to date, the Company believes that the impact of variable consideration on the Company’s revenue is not significant. ③ Performance obligations satisfied over time The Company provides its customers with services such as EPC business, O&M, etc. over time. The Company recognizes revenues based on the percentage-of-completion Under IFRS 15, an entity recognizes revenue over time if one of the following criteria is met: (a) the customer simultaneously receives and consumes the benefits provided by the entity’s performance as the entity performs; (b) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced; or (c) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. Based on the result of the detailed assessment to date, the impact of the revenue recognition over time based on the percentage-of-completion (iii) IFRS 16 ‘Leases’ IFRS 16 replaces IAS 17 ‘Leases’, and IFRIC 4 ‘Determining whether an Arrangement contains a Lease’. This standard is effective for annual reporting periods beginning on or after January 1, 2019, with early adoption permitted if IFRS 15 ‘Revenue from Contracts with Customers’ has also been applied. Under IFRS 16, a lessee shall apply this standard to its leases either: (a) retrospectively to each prior reporting period presented applying IAS 8 ‘Accounting Policies, Changes in Accounting Estimates and Errors’; or (b) retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application. The Company has not yet determined the transition approach for IFRS 16. IFRS 16 provides a single lessee accounting model in which the lessee recognizes lease related assets and liabilities in the statement of financial position. A lessee is required to recognize a right-of-use Upon adoption of IFRS 16, the nature of the costs associated with the lease will change as the operating lease payments recognized based on a straight-line basis will change to depreciation expense of a right-of-use The Company plans to conduct a detailed assessment of the potential impact from the application of IFRS 16 during the year ending December 31, 2018. (iv) IFRIC 22 ‘Foreign Currency Transactions and Advance Consideration’ IFRIC 22, published on December 8, 2016, clarifies the date of the transaction for the purpose of determining the exchange rate to use on initial recognition of the related asset, expense or income, when an entity has received or paid advance consideration in a foreign currency. IFRIC 22 is effective for annual reporting periods beginning on or after January 1, 2018, with earlier adoption permitted. The Company is currently performing a detailed assessment of the impact resulting from the application of IFRIC 22 and plans to complete the assessment in advance of its effective date. (v) Amendments to IAS 40 ‘Investment Property’ The amendments clarify when an entity should transfer a property asset to, or from, investment property. The amendments are effective for annual periods beginning on or after January 1, 2018, with earlier adoption permitted. The Company is currently performing a detailed assessment of the impact resulting from the application of amendments to IAS 40 and plans to complete the assessment in advance of its effective date.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Significant Accounting Policies	3. Significant Accounting Policies Except as described in note 2.(5), the Company applied the following significant accounting policies consistently for all periods presented. (1) Basis of consolidation The consolidated financial statements are the financial statements of a group in which the assets, liabilities, equity, income, expenses and cash flows of the parent and its subsidiaries are presented as those of a single economic entity. Subsidiaries are controlled by the Company. The Company controls an entity when it is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Income and expense of a subsidiary acquired or disposed of during the year are included in the consolidated statement of comprehensive income from the effective date of acquisition and up to the effective date of disposal, as appropriate. Total comprehensive income of subsidiaries is attributed to the owners of the Company and to the non-controlling non-controlling When necessary, adjustments are made to the financial statements of subsidiaries to bring their accounting policies into line with those of the Company. Transactions within the Company are eliminated during the consolidation. Changes in the Company’s ownership interests in a subsidiary that do not result in the Company losing control over the subsidiary are accounted for as equity transactions. The carrying amounts of the Company’s interests and the non-controlling non-controlling When the Company loses control of a subsidiary, the income or loss on disposal is calculated as the difference between (i) the aggregate of the fair value of the consideration received and the fair value of any retained interest and (ii) the previous carrying amount of the assets (including goodwill), and liabilities of the subsidiary and any non-controlling (2) Business combinations A business combination is accounted for by applying the acquisition method, unless it is a combination involving entities or businesses under common control. The consideration transferred in a business combination is measured at fair value, which is calculated as the sum of the acquisition-date fair values of the assets transferred by the Company, liabilities incurred by the Company to the former owners of the acquiree and the equity interests issued by the Company in exchange for control of the acquiree. Acquisition-related costs are generally recognized in income or loss as incurred. At the acquisition date, the identifiable assets acquired and the liabilities assumed are recognized at their fair value at the acquisition date, except that: • deferred tax assets or liabilities and liabilities or assets related to employee benefit arrangements are recognized and measured in accordance with IAS 12 ‘ Income Taxes’ and IAS 19 ‘ Employee Benefits’ respectively; • assets (or disposal groups) that are classified as held for sale in accordance with IFRS 5 ‘Non-current Goodwill is measured as the excess of the sum of the consideration transferred, the amount of any non-controlling non-controlling Non-controlling non-controlling transaction-by-transaction non-controlling The subsequent accounting for changes in the fair value of the contingent consideration that do not qualify as measurement period adjustments depends on how the contingent consideration is classified. Contingent consideration that is classified as equity is not re-measured re-measured When a business combination is achieved in stages, the Company’s previously held equity interest in the acquiree is re-measured If the initial accounting for a business combination is incomplete by the end of the reporting period in which the combination occurs, the Company reports provisional amounts for the items for which the accounting is incomplete. Those provisional amounts are adjusted during the measurement period (see above), or additional assets or liabilities are recognized, to reflect new information obtained about facts and circumstances that existed at the acquisition date that, if known, would have affected the amounts recognized at that date. The assets and liabilities acquired under business combinations under common control are recognized at the carrying amounts recognized previously in the consolidated financial statements of the ultimate parent. The difference between consideration transferred and carrying amounts of net assets acquired is recognized as part of share premium. (3) Investments in associates An associate is an entity over which the Company has significant influence and that is neither a subsidiary nor an interest in a joint venture. Significant influence is the power to participate in the financial and operating policy decisions of the investee but does not control or joint control over those policies. The results and assets and liabilities of associates are incorporated in these consolidated financial statements using the equity method of accounting. If the investment is classified as held for sale, in which case it is accounted for in accordance with IFRS 5 ‘Non-current After the disposal takes place, the Company shall account for any retained interest in associates in accordance with IAS 39 ‘Financial Instruments: Recognition and Measurement’ unless the retained interest continues to be an associates, in which case the entity uses the equity method. Under the equity method, an investment in an associate is initially recognized in the consolidated statement of financial position at cost and adjusted thereafter to recognize the Company’s share of the income or loss and other comprehensive income of the associate. When the Company’s share of losses of an associate exceeds the Company’s interest in that associate (which includes any long-term interests that, in substance, form part of the Company’s net investment in the associate), the Company discontinues recognizing its share of further losses. Additional losses are recognized only to the extent that the Company has incurred legal or constructive obligations or made payments on behalf of the associate. Any excess of the cost of acquisition over the Company’s share of the net fair value of the identifiable assets, liabilities and contingent liabilities of an associate recognized at the date of acquisition is recognized as goodwill, which is included within the carrying amount of the investment. Any excess of the Company’s share of the net fair value of the identifiable assets, liabilities and contingent liabilities over the cost of acquisition, after reassessment, is recognized immediately in income or loss. The requirements of IAS 39 ’Financial Instruments: Recognition and Measurement’, are applied to determine whether it is necessary to recognize any impairment loss with respect to the Company’s investment in an associate. When necessary, the entire carrying amount of the investment (including goodwill) is tested for impairment in accordance with IAS 36 ‘Impairment of Assets’ as a single asset by comparing its recoverable amount (higher of value in use and fair value less costs to sell) with its carrying amount, any impairment loss recognized forms part of the carrying amount of the investment. Any reversal of that impairment loss is recognized in accordance with IAS 36 to the extent that the recoverable amount of the investment subsequently increases. Upon disposal of an associate that results in the Company losing significant influence over that associate, any retained investment is measured at fair value at that date and the fair value is regarded as its fair value on initial recognition as a financial asset in accordance with IAS 39. The difference between the previous carrying amount of the associate attributable to the retained interest and its fair value is included in the determination of the gain or loss on disposal of the associate. In addition, the Company accounts for all amounts previously recognized in other comprehensive income in relation to that associate on the same basis as would be required if that associate had directly disposed of the related assets or liabilities. Therefore, if a gain or loss previously recognized in other comprehensive income by that associate would be reclassified to income or loss on the disposal of the related assets or liabilities, the Company reclassifies the gain or loss from equity to income or loss (as a reclassification adjustment) when it loses significant influence over that associate. When the Company transacts with its associate, incomes and losses resulting from the transactions with the associate are recognized in the Company’s consolidated financial statements only to the extent of interests in the associate that are not related to the Company. (4) Joint arrangements A joint arrangement is an arrangement of which two or more parties have joint control. Joint control is the contractually agreed sharing of control of an arrangement, which exists only when decisions about the relevant activities require the unanimous consent of the parties sharing control. Joint arrangements are classified into two types—joint operations and joint ventures. A joint operation is a joint arrangement whereby the parties that have joint control of the arrangement (i.e. joint operators) have rights to the assets, and obligations for the liabilities, relating to the arrangement. A joint venture is a joint arrangement whereby the parties that have joint control of the arrangement (i.e. joint ventures) have rights to the net assets of the arrangement. If the Company is a joint operator, the Company is to recognize and measure the assets and liabilities (and recognize the related revenues and expenses) in relation to its interest in the arrangement in accordance with relevant IFRSs applicable to the particular assets, liabilities, revenues and expenses. If the joint arrangement is a joint venture, the Company is to account for that investment using the equity method accounting in accordance with IAS 28 ‘Investment in Associates and Joint Ventures’ (refer to note 3.(3)), except when the Company is applicable to the IFRS 5 ‘Non-current (5) Non-current Non-current non-current When the Company is committed to a sale plan involving loss of control of a subsidiary, all of the assets and liabilities of that subsidiary are classified as held for sale when the criteria described above are met, regardless of whether the Company will retain a non-controlling Non-current (6) Goodwill The Company measures goodwill which acquired in a business combination at the amount recognized at the date on which it obtains control of the acquiree (acquisition date) less any accumulated impairment losses. Goodwill acquired in a business combination is allocated to each CGU that is expected to benefit from the synergies arising from the business acquired. The Company assesses at the end of each reporting period and whenever there is an indication that the asset may be impaired. An impairment loss is recognized if the carrying amount of an asset or a CGU exceeds its recoverable amount. Impairment losses are recognized in profit or loss. Any impairment identified at the CGU level will first reduce the carrying value of goodwill and then be used to reduce the carrying amount of the other assets in the CGU on a pro rata basis. Except for impairment losses in respect of goodwill which are never reversed, an impairment loss is reversed if there has been a change in the estimates used to determine the recoverable amount. An impairment loss is reversed only to the extent that the asset’s carrying amount does not exceed the carrying amount that would have been determined, net of depreciation or amortization, if no impairment loss had been recognized. (7) Revenue recognition Revenue from the sale of goods, rendering of services or use of the Company assets is measured at the fair value of the consideration received or receivable, net of returns, trade discounts and volume rebates, which are recognized as a reduction of revenue. Revenue is recognized when the amount of revenue can be measured reliably and it is probable that the economic benefits associated with the transaction will flow to the Company. (i) Sales of goods The Korean government approves the utility rates charged to customers by the Company’s power transmission and distribution division. The Company’s utility rates are designed to recover the Company’s reasonable costs plus a fair investment return. The Company recognize revenue from electricity sales revenue based on power sold (transferred to the customer) up to the reporting date and the corresponding utility rate charged to customers. To determine the amount of power sold, the Company estimates daily power volumes of electricity for residential, commercial, general, etc. The differences between the current month’s estimated amount and actual (meter-read) amount, is adjusted for (trued-up) (ii) Sales of services Revenue from services rendered is recognized in profit or loss in proportion to the stage of completion of the transaction at the reporting date. The stage of completion is assessed by reference to surveys of work performed or services performed to date as a percentage of total services to be performed or the proportion that costs incurred to date bear to the estimated total costs of the transaction or other methods that reliably measures the services performed. (iii) Dividend income and interest income Dividend income is recognized in profit or loss on the date that the Company’s right to receive payment is established, which in the case of quoted securities is the ex-dividend Interest income is recognized as it accrues in profit or loss, using the effective interest method. Interest income is accrued on a time basis, by reference to the principal outstanding and at the effective interest rate applicable, which is the rate that exactly discounts estimated future cash receipts through the expected life of the financial asset to that asset’s net carrying amount on initial recognition. (iv) Rental income The Company’s policy for recognition of revenue from operating leases is described in note 3.(9) below. (8) Construction services revenue The Company provides services related to the construction of power plants related to facilities of its customers, mostly in foreign countries. When the outcome of a construction contract can be estimated reliably, revenue and costs are recognized based on the stage of completion of the contract activity at the end of the reporting period, measured based on the proportion of contract costs incurred for work performed to date relative to the estimated total contract costs, except where this would not be representative of the stage of completion. Variations in contract work, claims and incentive payments are included to the extent that the amount can be measured reliably and its receipt is considered probable. When the outcome of a construction contract cannot be estimated reliably, contract revenue is recognized to the extent of contract costs incurred when it is probable the revenue will be realized. Contract costs are recognized as expenses in the period in which they are incurred. When it is probable that total contract costs will exceed total contract revenue, the expected loss is recognized as an expense immediately. When contract costs incurred to date plus recognized income less recognized losses exceed progress billings, the surplus is presented as amounts due from customers for contract work. For contracts where progress billings exceed contract costs incurred to date plus recognized income less recognized losses, the surplus is presented as the amounts due to customers for contract work. Amounts received before the related work is performed are included in the consolidated statements of financial position, as a liability, as advance received. Amounts billed for work performed but not yet paid by the customer are included in the consolidated statements of financial position as accounts and other receivables. (9) Leases The Company classifies and accounts for leases as either a finance or operating lease, depending on the terms. Leases where the Company assumes substantially all of the risks and rewards of ownership are classified as finance leases. All other leases are classified as operating leases. (i) The Company as lessor Amounts due from lessees under finance leases are recognized as receivables at the amount of the Company’s net investment in the leases. Finance lease income is allocated to accounting periods so as to reflect a constant periodic rate of return on the Company’s net investment outstanding in respect of the leases. Rental income from operating leases is recognized on a straight-line basis over the term of the relevant lease. Initial direct costs incurred in negotiating and arranging an operating lease are added to the carrying amount of the leased asset and recognized on a straight-line basis over the lease term. (ii) The Company as lessee Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards of ownership to the lessee. All other leases are classified as operating leases. Assets held under finance leases are initially recognized as assets of the Company at their fair value at the inception of the lease or, if lower, at the present value of the minimum lease payments. The corresponding liability to the lessor is included in the statement of financial position as a finance lease obligation. Lease payments are apportioned between finance expenses and reduction of the lease obligation so as to achieve a constant rate of interest on the remaining balance of the liability. Finance expenses are recognized immediately in income or loss, unless they are directly attributable to qualifying assets, in which case they are capitalized in accordance with the Company’s general policy on borrowing costs. Contingent rentals are recognized as expenses in the periods in which they are incurred. Operating lease payments are recognized as an expense on a straight-line basis over the lease term, except where another systematic basis is more representative of the time pattern in which economic benefits from the leased asset are consumed. Contingent rentals arising under operating leases are recognized as an expense in the period in which they are incurred. In the event that lease incentives are received to enter into operating leases, such incentives are recognized as a liability. The aggregate benefit of incentives is recognized as a reduction of rental expense on a straight-line basis, except where another systematic basis is more representative of the time pattern in which economic benefits from the leased asset are consumed. (iii) Determining whether an arrangement contains a lease At inception of an arrangement, the Company determines whether the arrangement is or contains a lease. At inception or on reassessment of an arrangement that contains a lease, the Company separates payments and other consideration required by the arrangement into those for the lease and those for other elements on the basis of their relative fair values. If the Company concludes for a finance lease that it is impracticable to separate the payments reliably, then an asset and a liability are recognized at an amount equal to the fair value of the underlying asset. (10) Foreign currencies Transactions in foreign currencies are translated to the respective functional currencies of the Company entities at exchange rates at the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are retranslated to the functional currency using the reporting date’s exchange rate. Non-monetary Exchange differences are recognized in profit or loss in the period in which they arise except for: • Exchange differences on foreign currency borrowings relating to assets under construction for future productive use, which are included in the cost of those assets when they are regarded as an adjustment to interest costs on those foreign currency borrowings; • Exchange differences on transactions entered into in order to hedge certain foreign currency risks (refer to note 3.(25) Derivative financial instruments, including hedge accounting); and • Exchange differences on monetary items receivable from or payable to a foreign operation for which settlement is neither planned nor likely to occur (therefore forming part of the net investment in the foreign operation), which are recognized initially in other comprehensive income and reclassified from equity to income or loss on disposal or partial disposal of the net investment. For the purpose of presenting financial statements, the assets and liabilities of the Company’s foreign operations are expressed in Korean won using exchange rates prevailing at the end of the reporting period. Income and expense items are translated at the average exchange rates for the period, unless exchange rates fluctuated significantly during that period, in which case the exchange rates at the dates of the transactions are used. Exchange differences arising, if any, are recognized in other comprehensive income and accumulated in equity. When a foreign operation is disposed of, the relevant amount in the translation is transferred to profit or loss as part of the gain or loss on disposal. (11) Borrowing costs The Company capitalizes borrowing costs directly attributable to the acquisition, construction or production of a qualifying asset as part of the cost of that asset. Other borrowing costs are recognized in expense as incurred. A qualifying asset is an asset that requires a substantial period of time to get ready for its intended use or sale. Investment income earned on the temporary investment of specific borrowings pending their expenditure on qualifying assets is deducted from the borrowing costs eligible for capitalization. All other borrowing costs are recognized in income or loss in the period in which they are incurred. (12) Government grants and income related to transfer of assets from customers Government grants are not recognized unless there is reasonable assurance that the Company will comply with the grant’s conditions and that the grant will be received. Benefit from a government loan at a below-market interest rate is treated as a government grant, measured as the difference between proceeds received and the fair value of the loan based on prevailing market interest rates. (i) If the Company received grants related to assets Government grants whose primary condition is that the Company purchase, construct or otherwise acquire long-term assets are deducted in calculating the carrying amount of the asset. The grant is recognized in profit or loss over the life of a depreciable asset as a reduced depreciation expense. (ii) If the Company received grants related to income Government grants which are intended to compensate the Company for expenses incurred are recognized as other income (government grants) in profit or loss over the periods in which the Company recognizes the related costs as expenses. The Company recovers a substantial amount of the cost related to its electric power distribution facilities from customers through the transfer of assets, while the remaining portion is recovered through electricity sales from such customers in the future. As such, the Company believes there exists a continued service obligation to the customers in accordance with IFRIC 18 ‘Transfer of Assets from Customers’ when the Company receives an item of property, equipment, or cash for constructing or acquiring an item of property or equipment, in exchange for supplying electricity to customers. The Company defers the amounts received, which are subsequently recognized as other income on a straight-line basis over the estimated service period which does not exceed the transferred asset’s useful life. (13) Employee benefits When an employee has rendered service to the Company during a period, the Company recognizes the contribution payable to a defined contribution plan in exchange for that service as a liability (accrued expense). For defined benefit pension plans and other post-employment benefits, the net periodic pension expense is actuarially determined by “Pension Actuarial System” developed by independent actuaries using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid and that have terms to maturity approximating the terms of the related pension liability. However, if there is not a deep market, market yields on government bonds are used. Net defined benefit liability’s measurement is composed of actuarial gains and losses, return on plan assets excluding net interest on net defined benefit liability, and any change in the effect of the asset ceiling, excluding net interest, which are immediately recognized in other comprehensive income. The actuarial gains or losses recognized in other comprehensive income which will not be reclassified into net profit or loss for later periods are immediately recognized in retained earnings. Past service cost will be recognized as expenses upon the earlier of the date of change or reduction to the plan, or the date of recognizing termination benefits. The retirement benefit obligation recognized in the statement of financial position represents the present value of the defined benefit obligation as adjusted for unrecognized actuarial gains and losses and unrecognized past service cost, and as reduced by the fair value of plan assets. Any asset resulting from this calculation is limited to unrecognized actuarial losses and past service cost, plus the present value of available refunds and reductions in future contributions to the plan. (14) Income taxes Income tax expense comprises current and deferred tax. Current tax and deferred tax are recognized in profit or loss except to the extent that it relates to a business combination, or items recognized directly in equity or in other comprehensive income. (i) Current tax Current tax is the expected tax payable or receivable on the taxable profit or loss for the year, using tax rates enacted or substantively enacted at the end of the reporting period and any adjustment to tax payable in respect of previous years. The taxable profit is different from the accounting profit for the period since the taxable profit is calculated excluding the temporary differences, which will be taxable or deductible in determining taxable profit (tax loss) of future periods, and non-taxable non-deductible (ii) Deferred tax Deferred tax is recognized, using the asset-liability method, in respect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for taxation purposes. A deferred tax liability is recognized for all taxable temporary differences. A deferred tax asset is recognized for all deductible temporary differences to the extent that it is probable that taxable profit will be available against which they can be utilized. However, deferred tax is not recognized for the following temporary differences: taxable temporary differences arising on the initial recognition of goodwill, or the initial recognition of assets or liabilities in a transaction that is not a business combination and that affects neither accounting profit or loss nor taxable income. The measurement of deferred tax liabilities and deferred tax assets reflects the tax consequences that would follow from the manner in which the Company expects, at the end of the reporting period, to recover or settle the carrying amount of its assets and liabilities. Deferred tax assets or deferred tax liabilities on investment properties measured at fair value, unless any contrary evidence exists, are measured using the assumption that the carrying amount of the property will be recovered entirely through sale. The Company recognizes a deferred tax liability for all taxable temporary differences associated with investments in subsidiaries, associates, and interests in joint ventures, except to the extent that the Company is able to control the timing of the reversal of the temporary difference and it is probable that the temporary difference will not reverse in the foreseeable future. The Company recognizes a deferred tax asset for all deductible temporary differences arising from investments in subsidiaries and associates, to the extent that it is probable that the temporary difference will reverse in the foreseeable future and taxable profit will be available against which the temporary difference can be utilized. The carrying amount of a deferred tax asset is reviewed at the end of each reporting period and reduces the carrying amount to the extent that it is no longer probable that sufficient taxable profit will be available to allow the benefit of part or all of that deferred tax asset to be utilized. Deferred tax assets and liabilities are measured at the tax rates that are expected to apply to the period when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period. The measurement of deferred tax liabilities and deferred tax assets reflects the tax consequences that would follow from the manner in which the Company expects, at the end of the reporting period to recover or settle the carrying amount of its assets and liabilities. Deferred tax assets and liabilities are offset only if there is a legally enforceable right to offset the related current tax liabilities and assets, and they relate to income taxes levied by the same tax authority and they intend to settle current tax liabilities and assets on a net basis. (iii) Current and deferred tax for the year Current and deferred tax are recognized in income or loss, except when they relate to items that are recognized in other comprehensive income or directly in equity, in which case, the current and deferred tax are also recognized in other comprehensive income or directly in equity respectively. Where current tax or deferred tax arises from the initial accounting for a business combination, the tax effect is included in the accounting for the business combination. (15) Property, plant and equipment Property, plant and equipment are initially measured at cost and after initial recognition, are carried at cost less accumulated depreciation and accumulated impairment losses. The cost of property, plant and equipment includes expenditures arising directly from the construction or acquisition of the asset, any costs directly attributable to bringing the asset to the location and condition necessary for it to be capable of operating in the manner intended by management and the initial estimate of the costs of dismantling and removing the item and restoring the site on which it is located. Subsequent costs are recognized in the carrying amount of property, plant and equipment at cost or, if appropriate, as separate items if it is probable that future economic benefits associated with the item will flow to the Company and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day Property, plant and equipment, except for land, are depreciated on a straight-line basis over estimated useful lives that appropriately reflect the pattern in which the asset’s future economic benefits are expected to be consumed. For loaded nuclear fuel related to long-term raw materials and spent nuclear fuels related to asset retirement costs, the Company uses the production method to measure and recognizes as expense the economic benefits of the assets. The estimated useful lives of the Company’s property, plant and equipment are as follows: Useful lives (years) Buildings 8 ~ 40 Structures 8 ~ 50 Machinery 2 ~ 32 Vehicles 3 ~ 8 Loaded heavy water 30 Asset retirement costs 18, 30, 40, 60 Finance lease assets 6 ~ 32 Ships 9 Others 4 ~ 15 A component that is significant compared to the total cost of property, plant and equipment is depreciated over its separate useful life. Depreciation methods, residual values and useful lives of property, plant and equipment are reviewed at the end of each reporting period and if change is deemed appropriate, it is treated as a change in accounting estimate. As a result of such annual review, useful lives of cer

Segment, Geographic and Other I

Segment, Geographic and Other Information	12 Months Ended
	Dec. 31, 2017
Segment, Geographic and Other Information [Abstract]
Segment, Geographic and Other Information	4. Segment, Geographic and Other Information (1) Segment determination and explanation of the measurements The Company’s operating segments are its business components that generate discrete financial information that is reported to and regularly reviewed by the Company’s the chief operating decision maker, the Chief Executive Officer, for the purpose of resource allocation and assessment of segment performance. The Company’s reportable segments are ‘Transmission and distribution’, ‘Electric power generation (Nuclear)’, ‘Electric power generation (Non-nuclear)’, Segment operating profit (loss) is determined the same way that consolidated operating profit is determined under IFRS without any adjustment for corporate allocations. The accounting policies used by each segment are consistent with the accounting policies used in the preparation of the consolidated financial statements. Segment assets and liabilities are determined based on separate financial statements of the entities instead of on a consolidated basis. There are various transactions between the reportable segments, including sales of property, plant and equipment and so on, that are conducted on an arms-length basis at market prices that would be applicable to an independent third-party. For subsidiaries which are in a different segment from that of its immediate parent company, their carrying amount in separate financial statements is eliminated in the consolidating adjustments in the tables below. In addition, consolidation adjustments in the table below include adjustments of the amount of investment in associates and joint ventures from the cost basis amount reflected in segment assets to that determined using equity method in the consolidated financial statements. (2) Financial information of the segments for the years ended December 31, 2015, 2016 and 2017, respectively, are as follows: 2015 Segment Total Intersegment Revenue Depreciation Interest Interest Profit (loss) Employee Loss on Increase in Operating In millions of won Transmission and distribution ￦ 58,164,394 1,230,975 56,933,419 2,859,037 132,809 1,092,594 220,406 135,261 359,521 872,096 13,319,310 Electric power generation (Nuclear) 10,642,352 10,596,189 46,163 3,070,828 24,612 532,490 (595 ) 54,572 — 401,839 3,806,617 Electric power generation (Non-nuclear) 21,469,345 20,906,081 563,264 2,337,353 22,171 319,647 (10,686 ) 74,007 5,305 148,053 2,704,260 Plant maintenance & engineering service 2,533,887 2,016,699 517,188 85,662 12,293 542 (1,746 ) 74,542 — 174,912 332,531 Others 672,250 150,557 521,693 27,491 108,104 127,684 — 343 230 34 80,165 Consolidation adjustments (34,900,501 ) (34,900,501 ) — (38,987 ) (58,404 ) (57,273 ) — (24,033 ) — 5,790 37,993 ￦ 58,581,727 — 58,581,727 8,341,384 241,585 2,015,684 207,379 314,692 365,056 1,602,724 20,280,876 Finance income 1,182,988 Finance expense (3,015,457 ) Profit related to associates and joint ventures 207,379 Profit before income tax ￦ 18,655,786 2016 Segment Total Intersegment Revenue Depreciation Interest Interest Profit (loss) Employee Loss on Increase in Operating In millions of won Transmission and distribution ￦ 59,862,284 1,890,489 57,971,795 3,226,700 80,882 844,200 (128,402 ) 162,326 424,356 711,430 5,274,308 Electric power generation (Nuclear) 11,168,579 11,129,385 39,194 3,130,820 33,111 474,590 (1,082 ) 70,582 — 576,223 3,770,165 Electric power generation (Non-nuclear) 21,394,223 20,561,044 833,179 2,523,306 24,171 359,607 (8,342 ) 79,846 2,133 276,619 3,211,684 Plant maintenance & engineering service 2,618,388 2,190,207 428,181 98,843 10,672 2,156 478 86,268 — 221,301 210,680 Others 567,836 77,098 490,738 26,817 115,928 97,926 — 1,050 30 168 76,336 Consolidation adjustments (35,848,223 ) (35,848,223 ) — (45,498 ) (22,986 ) (25,611 ) — (26,319 ) — (3,009 ) (246,813 ) ￦ 59,763,087 — 59,763,087 8,960,988 241,778 1,752,868 (137,348 ) 373,753 426,519 1,782,732 12,296,360 Finance income 791,543 Finance expense (2,437,087 ) Loss related to associates and joint ventures (137,348 ) Profit before income tax ￦ 10,513,468 2017 Segment Total Intersegment Revenue Depreciation Interest Interest Profit (loss) Employee Loss on Increase in Operating In millions of won Transmission and distribution ￦ 59,486,766 2,044,160 57,442,606 3,466,410 49,987 737,971 (105,166 ) 158,738 384,595 885,195 1,902,634 Electric power generation (Nuclear) 9,415,752 9,359,468 56,284 3,267,510 21,034 487,503 3,637 80,809 — 801,800 1,347,794 Electric power generation (Non-nuclear) 22,795,816 21,885,251 910,565 2,954,375 18,860 486,176 (6,718 ) 94,075 39,335 171,457 1,523,497 Plant maintenance & engineering service 2,621,440 2,211,716 409,724 109,001 10,801 2,967 (70 ) 87,344 161 219,382 265,593 Others 655,062 138,352 516,710 36,001 130,003 103,782 — 861 — (967 ) 113,296 Consolidation adjustments (35,638,947 ) (35,638,947 ) — (59,586 ) (24,542 ) (28,847 ) — (30,467 ) — (386,747 ) 167,055 ￦ 59,335,889 — 59,335,889 9,773,711 206,143 1,789,552 (108,317 ) 391,360 424,091 1,690,120 5,319,869 Finance income 1,530,618 Finance expense (3,127,952 ) Loss related to associates and joint ventures (108,317 ) Profit before income tax ￦ 3,614,218 (3) Information related to segment assets and segment liabilities as of and for the years ended December 31, 2016 and 2017 are as follows: 2016 Segment Segment assets Investments Acquisition of non-current Segment In millions of won Transmission and distribution ￦ 105,321,129 4,121,462 6,345,004 49,854,420 Electric power generation (Nuclear) 52,782,915 15,384 1,945,610 27,366,938 Electric power generation (Non-nuclear) 47,427,642 1,320,203 3,508,313 26,205,049 Plant maintenance & engineering service 3,106,909 53,399 180,715 1,218,047 Others 7,423,132 — 365,470 2,761,262 Segment totals 216,061,727 5,510,448 12,345,112 107,405,716 Consolidation adjustments: Elimination of inter-segment amounts (39,114,371 ) — (191,901 ) (5,811,800 ) Equity method adjustment 906,239 — — — Deferred taxes (5,830 ) — — 4,301,404 Others (10,723 ) — — (1,108,823 ) (38,224,685 ) — (191,901 ) (2,619,219 ) Consolidated totals ￦ 177,837,042 5,510,448 12,153,211 104,786,497 2017 Segment Segment assets Investments Acquisition of non-current Segment In millions of won Transmission and distribution ￦ 106,540,154 3,366,309 6,606,512 50,757,798 Electric power generation (Nuclear) 55,011,096 11,843 2,083,967 29,252,816 Electric power generation (Non-nuclear) 47,938,084 1,904,224 3,250,524 26,337,295 Plant maintenance & engineering service 3,273,959 48,320 145,779 1,176,627 Others 7,798,400 — 569,447 3,013,743 Segment totals 220,561,693 5,330,696 12,656,229 110,538,279 Consolidation adjustments: Elimination of inter-segment amounts (39,517,829 ) — 23,616 (5,239,156 ) Equity method adjustment 754,314 — — — Deferred taxes 2,215 — — 5,339,450 Others (11,478 ) — — (1,814,299 ) (38,772,778 ) — 23,616 (1,714,005 ) Consolidated totals ￦ 181,788,915 5,330,696 12,679,845 108,824,274 (4) Geographic information Electric sales, the main operations of the Company, are conducted in the Republic of Korea where the controlling company is located. The following information on revenue from external customers and non-current Geographical unit Revenue from external customers Non-current 2015 2016 2017 2015 2016 2017 In millions of won Domestic ￦ 54,351,076 55,310,011 55,652,807 143,788,043 148,297,677 153,436,810 Overseas(*1) 4,230,651 4,453,076 3,683,082 4,526,395 4,474,699 4,497,535 ￦ 58,581,727 59,763,087 59,335,889 148,314,438 152,772,376 157,934,345 (*1) Middle East and other Asian countries make up the majority of overseas revenue and non-current (*2) Amount excludes financial assets and deferred tax assets. (5) Information on significant customers There is no individual customer comprising more than 10% of the Company’s revenue for the years ended December 31, 2015, 2016 and 2017.

Classification of Financial Ins

Classification of Financial Instruments	12 Months Ended
	Dec. 31, 2017
Classification of Financial Instruments [Abstract]
Classification of Financial Instruments	5. Classification of Financial Instruments (1) Classification of financial assets as of December 31, 2016 and 2017 are as follows: 2016 Financial Loans and Available-for-sale Held-to-maturity Derivative assets Total In millions of won Current assets Cash and cash equivalents ￦ — 3,051,353 — — — 3,051,353 Current financial assets Held-to-maturity — — — 114 — 114 Derivative assets 79,709 — — — 113,574 193,283 Other financial assets — 2,478,592 — — — 2,478,592 Trade and other receivables — 7,788,876 — — — 7,788,876 79,709 13,318,821 — 114 113,574 13,512,218 Non-current Non-current Available-for-sale — — 1,014,732 — — 1,014,732 Held-to-maturity — — — 3,130 — 3,130 Derivative assets 287,768 — — — 300,323 588,091 Other financial assets — 1,051,541 — — — 1,051,541 Trade and other receivables — 1,903,515 — — — 1,903,515 287,768 2,955,056 1,014,732 3,130 300,323 4,561,009 ￦ 367,477 16,273,877 1,014,732 3,244 413,897 18,073,227 2017 Financial Loans and Available-for-sale Held-to-maturity Derivative assets Total In millions of won Current assets Cash and cash equivalents ￦ — 2,369,739 — — — 2,369,739 Current financial assets Held-to-maturity — — — 5 — 5 Derivative assets 12,923 — — — 12 12,935 Other financial assets — 1,945,417 — — — 1,945,417 Trade and other receivables — 7,928,972 — — — 7,928,972 12,923 12,244,128 — 5 12 12,257,068 Non-current Non-current Available-for-sale — — 699,833 — — 699,833 Held-to-maturity — — — 3,139 — 3,139 Derivative assets 9,097 — — — 10,594 19,691 Other financial assets 111,512 1,204,738 — — — 1,316,250 Trade and other receivables — 1,754,797 — — — 1,754,797 120,609 2,959,535 699,833 3,139 10,594 3,793,710 ￦ 133,532 15,203,663 699,833 3,144 10,606 16,050,778 (2) Classification of financial liabilities as of December 31, 2016 and 2017 are as follows: 2016 Financial liabilities at fair value through profit or loss Financial liabilities Derivative liabilities Total In millions of won Current liabilities Borrowings ￦ — 1,115,521 — 1,115,521 Debt securities — 7,823,557 — 7,823,557 Derivative liabilities 3,251 — — 3,251 Trade and other payables — 5,585,411 — 5,585,411 3,251 14,524,489 14,527,740 Non-current Borrowings — 1,773,891 — 1,773,891 Debt securities — 42,926,236 — 42,926,236 Derivative liabilities 18,278 — 117,157 135,435 Trade and other payables — 3,558,175 — 3,558,175 18,278 48,258,302 117,157 48,393,737 ￦ 21,529 62,782,791 117,157 62,921,477 2017 Financial liabilities at fair value through profit or loss Financial liabilities Derivative liabilities Total In millions of won Current liabilities Borrowings ￦ — 1,165,985 — 1,165,985 Debt securities — 7,957,300 — 7,957,300 Derivative liabilities 51,090 — 20,177 71,267 Trade and other payables — 5,999,521 — 5,999,521 51,090 15,122,806 20,177 15,194,073 Non-current Borrowings — 2,434,624 — 2,434,624 Debt securities — 43,189,483 — 43,189,483 Derivative liabilities 99,839 — 256,953 356,792 Trade and other payables — 3,223,480 — 3,223,480 99,839 48,847,587 256,953 49,204,379 ￦ 150,929 63,970,393 277,130 64,398,452 (3) Classification of comprehensive income (loss) from financial instruments for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Cash and cash equivalents Interest income ￦ 54,687 61,380 35,474 Available-for-sale Dividends income 14,069 9,446 11,477 Impairment loss on available-for-sale financial assets (84,370 ) (86,703 ) (2,713 ) Gain (loss) on disposal of available-for-sale (3,004 ) 1,473 (1,213 ) Interest income 29 — — Held-to-maturity Interest income 99 97 82 Loans and receivables Interest income 28,586 25,106 30,014 Trade and other receivables Interest income 100,771 102,237 102,727 Short-term financial instruments Interest income 46,921 45,763 29,412 Long-term financial instruments Interest income 10,492 7,195 8,144 Financial assets at fair value through profit or loss Interest income — — 290 Gain (loss) on valuation of derivatives 220,285 113,671 (214,100 ) Gain (loss) on transaction of derivatives 8,605 (8,039 ) (37,266 ) Gain on valuation of financial assets — — 12 Derivative assets (using hedge accounting) Gain (loss) on valuation of derivatives (profit or loss) 244,020 145,458 (41,129 ) Gain (loss) on valuation of derivatives (equity, before tax)(*) (12,572 ) 50,047 2,453 Gain (loss) on transaction of derivatives 2,818 (13,994 ) (58,299 ) Financial liabilities carried at amortized cost Interest expense of borrowings and debt securities (1,392,477 ) (1,202,065 ) (1,240,727 ) Loss on retirement of financial liabilities (33 ) (23,000 ) (5 ) Interest expense of trade and other payables (84,527 ) (68,375 ) (57,160 ) Interest expense of others (538,680 ) (482,428 ) (491,665 ) Gain (loss) on foreign currency transactions and translations (708,178 ) (290,485 ) 1,075,215 Financial liabilities at fair value through profit or loss Gain (loss) on valuation of derivatives 35,312 23,225 (179,879 ) Gain (loss) on transaction of derivatives 107,454 17,045 (27,175 ) Derivative liabilities (using hedge accounting) Gain (loss) on valuation of derivatives (profit or loss) 93,914 5,714 (439,559 ) Gain (loss) on valuation of derivatives (equity, before tax)(*) 9,728 (3,297 ) 29,431 Loss on transaction of derivatives (4,288 ) (51,450 ) (46,221 ) (*) Items are included in other comprehensive income or loss. All other income and gain amounts listed above are included in finance income, and all expense and losses listed above are included in finance expenses in the consolidated statements of comprehensive income or loss.

Restricted Deposits

Restricted Deposits	12 Months Ended
	Dec. 31, 2017
Restricted Deposits [Abstract]
Restricted Deposits	6. Restricted Deposits Restricted deposits as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Cash and cash equivalents Escrow accounts ￦ 91 53 Deposits for government project 16,457 15,365 Collateral provided for borrowings 80,327 79,569 Collateral provided for lawsuit 241 2 Deposits for transmission regional support program 2,137 2,320 Short-term financial instruments Bidding guarantees 118 119 Restriction on withdrawal related to ‘win-win for small and medium enterprises 33,000 34,000 Other current receivables Deposit for lawsuit 16,000 — Financial assets at fair value through profit or loss Decommissioning costs of nuclear power plants — 108,512 Non-current available-for-sale Decommissioning costs of nuclear power plants 437,015 214,156 Long-term financial instruments Guarantee deposits for checking account 2 2 Guarantee deposits for banking accounts at oversea branches 342 302 Decommissioning costs of nuclear power plants 214,121 337,234 Funds for developing small and medium enterprises(*) 200,000 200,000 ￦ 999,851 991,634 (*1) Deposits for small and medium enterprise at IBK and others for construction of Bitgaram Energy Valley and support for the high potential businesses as of December 31, 2017 and 2016.

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	7. Cash and Cash Equivalents Cash and cash equivalents as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Cash ￦ 119 132 Other demand deposits 1,725,785 968,966 Short-term deposits classified as cash equivalents 120,594 559,239 Short-term investments classified as cash equivalents 1,204,855 841,402 ￦ 3,051,353 2,369,739

Trade and Other Receivables

Trade and Other Receivables	12 Months Ended
	Dec. 31, 2017
Trade and Other Receivables [Abstract]
Trade and Other Receivables	8. Trade and Other Receivables (1) Trade and other receivables as of December 31, 2016 and 2017 are as follows: 2016 Gross Allowance for Present value discount Book In millions of won Current assets Trade receivables ￦ 7,260,227 (71,985 ) — 7,188,242 Other receivables 652,782 (50,071 ) (2,077 ) 600,634 7,913,009 (122,056 ) (2,077 ) 7,788,876 Non-current Trade receivables 491,509 — — 491,509 Other receivables 1,455,860 (37,590 ) (6,264 ) 1,412,006 1,947,369 (37,590 ) (6,264 ) 1,903,515 ￦ 9,860,378 (159,646 ) (8,341 ) 9,692,391 2017 Gross Allowance for Present value discount Book In millions of won Current assets Trade receivables ￦ 7,499,285 (173,583 ) — 7,325,702 Other receivables 614,212 (9,199 ) (1,743 ) 603,270 8,113,497 (182,782 ) (1,743 ) 7,928,972 Non-current Trade receivables 449,191 — (414 ) 448,777 Other receivables 1,380,983 (68,809 ) (6,154 ) 1,306,020 1,830,174 (68,809 ) (6,568 ) 1,754,797 ￦ 9,943,671 (251,591 ) (8,311 ) 9,683,769 (2) Other receivables as of December 31, 2016 and 2017 are as follows: 2016 Gross Allowance for Present value Book In millions of won Current assets Non-trade ￦ 360,021 (50,071 ) — 309,950 Accrued income 62,063 — — 62,063 Deposits 193,720 — (2,077 ) 191,643 Finance lease receivables 12,225 — — 12,225 Others 24,753 — — 24,753 652,782 (50,071 ) (2,077 ) 600,634 Non-current Non-trade 80,393 (26,942 ) — 53,451 Accrued income 174 — — 174 Deposits 320,935 — (6,264 ) 314,671 Finance lease receivables 960,649 — — 960,649 Others 93,709 (10,648 ) — 83,061 1,455,860 (37,590 ) (6,264 ) 1,412,006 ￦ 2,108,642 (87,661 ) (8,341 ) 2,012,640 2017 Gross amount Allowance for Present value Book In millions of won Current assets Non-trade ￦ 314,256 (9,199 ) — 305,057 Accrued income 54,002 — — 54,002 Deposits 228,317 — (1,743 ) 226,574 Finance lease receivables 13,067 — — 13,067 Others 4,570 — — 4,570 614,212 (9,199 ) (1,743 ) 603,270 Non-current Non-trade 112,983 (59,117 ) — 53,866 Accrued income 182 — — 182 Deposits 331,071 — (6,154 ) 324,917 Finance lease receivables 849,554 — — 849,554 Others 87,193 (9,692 ) — 77,501 1,380,983 (68,809 ) (6,154 ) 1,306,020 ￦ 1,995,195 (78,008 ) (7,897 ) 1,909,290 (3) Trade and other receivables are classified as loans and receivables, and are measured using the effective interest method. No interest is accrued for trade receivables related to electricity for the duration between the billing date and the payment due dates. But once trade receivables are overdue, the Company imposes a monthly interest rate of 1.5% on the overdue trade receivables. The Company holds deposits of three months’ expected electricity usage for customers requesting temporary usage and customers with past defaulted payments. (4) Aging analysis of trade receivables as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Trade receivables: (not overdue, not impaired) ￦ 7,592,363 7,698,604 Trade receivables: (overdue, not impaired) 820 7,117 Less than 60 days 820 7,117 Trade receivables: (impairment reviewed) 158,553 242,755 60 ~ 90 days 44,277 39,070 90 ~ 120 days 18,917 17,502 120 days ~ 1year 42,534 55,242 Over 1 year 52,825 130,941 7,751,736 7,948,476 Less: allowance for doubtful accounts (71,985 ) (173,583 ) Less: present value discount — (414 ) ￦ 7,679,751 7,774,479 The Company assesses at the end of each reporting period whether there is any objective evidence that trade receivables are impaired, and provides allowances for doubtful accounts which includes impairment for trade receivables that are individually significant. The Company considers receivables as overdue if the receivables are outstanding 60 days after the maturity and sets an allowance based on past experience of collection. (5) Aging analysis of other receivables as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Other receivables: (not overdue, not impaired) ￦ 1,887,620 1,810,075 Other receivables: (overdue, not impaired) 46,887 47,532 Less than 60 days 46,887 47,532 Other receivables: (impairment reviewed) 174,135 137,588 60 ~ 90 days 7,352 44 90 ~ 120 days 2,160 1,017 120 days ~ 1year 17,613 11,042 Over 1 year 147,010 125,485 2,108,642 1,995,195 Less: allowance for doubtful accounts (87,661 ) (78,008 ) Less: present value discount (8,341 ) (7,897 ) ￦ 2,012,640 1,909,290 (6) Changes in the allowance for doubtful accounts for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 Trade Other Trade Other Trade Other In millions of won Beginning balance ￦ 80,644 67,932 51,956 91,746 71,985 87,661 Bad debt expense 1,308 18,473 38,719 233 126,714 1,778 Write-off (28,978 ) (888 ) (18,939 ) (928 ) (32,995 ) (3,129 ) Reversal (1,018 ) (413 ) — (5,489 ) — (2,166 ) Others — 6,642 249 2,099 7,879 (6,136 ) Ending balance ￦ 51,956 91,746 71,985 87,661 173,583 78,008

Available-for-sale Financial As

Available-for-sale Financial Assets	12 Months Ended
	Dec. 31, 2017
Available-for-sale Financial Assets [Abstract]
Available-for-sale Financial Assets	9. Available-for-sale (1) Changes in available-for-sale 2016 Beginning Acquisition Disposal(*1) Valuation Impairment Others Ending In millions of won Listed ￦ 196,579 — (3,398 ) 74,139 (9,122 ) 9,973 268,171 Unlisted 387,900 449,484 (1,828 ) (12,346 ) (77,581 ) 932 746,561 584,479 449,484 (5,226 ) 61,793 (86,703 ) 10,905 1,014,732 Short-term available-for-sale — — — — — — — Long-term available-for-sale ￦ 584,479 449,484 (5,226 ) 61,793 (86,703 ) 10,905 1,014,732 (*1) The Company recognized gain and loss on disposal of available-for-sale IBK-AUCTUS 2017 Beginning Acquisition Disposal(*1) Valuation Impairment Others Ending In millions of won Listed ￦ 268,171 106 — 8,156 (97 ) (1,883 ) 274,453 Unlisted 746,561 233,179 (461,423 ) (2,908 ) (2,616 ) (87,413 ) 425,380 1,014,732 233,285 (461,423 ) 5,248 (2,713 ) (89,296 ) 699,833 Short-term available-for-sale — — — — — — — Long-term available-for-sale ￦ 1,014,732 233,285 (461,423 ) 5,248 (2,713 ) (89,296 ) 699,833 (*1) The Company recognized gain and loss on disposal of available-for-sale 2016 Shares Ownership Acquisition Book value Fair value In millions of won Listed Korea District Heating Corp. 2,264,068 19.55 % ￦ 173,201 154,183 154,183 Ssangyong Motor Co., Ltd. 38,568 0.03 % 428 304 304 Sungjee Construction. Co., Ltd. 10,530 0.01 % 49 21 21 Korea Line Corp. 18 0.00 % 1 — — Namkwang Engineering & Construction Co., Ltd. 46 0.00 % 15 — — Pumyang Construction Co., Ltd. 7 0.00 % 2 — — ELCOMTEC Co., Ltd. 32,875 0.04 % 217 74 74 PAN ocean Co., Ltd. 1,492 0.00 % 14 7 7 Borneo International Furniture Co., Ltd. 64,037 0.28 % 97 103 103 Dongbu Corporation 1,229 0.02 % 12 12 12 PT Adaro Energy Tbk 480,000,000 1.50 % 71,554 73,061 73,061 Energy Fuels Inc. 1,711,814 2.59 % 16,819 3,385 3,385 Baralaba Coal Company Limited(*6) 99,763 0.07 % 18,445 42 42 Denison Mines Corp. 58,284,000 10.93 % 84,134 36,504 36,504 Fission 3.0 300,000 0.17 % — 16 16 Fission Uranium Corp. 800,000 0.17 % 785 459 459 365,773 268,171 268,171 Unlisted(*1) K&C—Gyeongnam youth job creation Investment Fund 24 10.00 % 1,207 1,207 — Korea investment—Korea EXIM Bank CERs Private Special Assets Investment Trust I 1,758,731,002 14.18 % 1,752 571 — Troika Overseas Resource Development Private Equity Firm 13,340,012,100 3.66 % 13,340 1,553 — IBK-AUCTUS 152 6.29 % 41 41 — Global Dynasty Overseas Resource Development Private Equity Firm 2,233,407,439 7.46 % 2,233 2,233 — Intellectual Discovery, Ltd. 1,000,000 8.81 % 5,000 1,375 — Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 4,256,096,329 5.00 % 4,389 4,389 — Construction Guarantee(*2) 571 0.02 % 601 819 819 Plant & Mechanical Contractors Financial Cooperative of Korea 50 0.01 % 36 36 — Fire Guarantee 40 0.02 % 20 20 — Korea Software Financial Cooperative 5,186 1.39 % 3,301 3,301 — Engineering Financial Cooperative 486 0.05 % 60 60 — Electric Contractors Financial Cooperative 800 0.03 % 152 152 — Korea Specialty Contractor Financial Cooperative 476 0.01 % 417 417 — Information & Communication Financial Cooperative 70 0.01 % 10 10 — Korea Electric Engineers Association 400 0.24 % 40 40 — Korea investment—Investment Pool for Public funds 10(*5) — — 142,470 141,315 141,315 2016 Shares Ownership Acquisition Book value Fair value In millions of won Samsung investment—Investment Pool for Public funds 2(*5) — — ￦ 213,710 211,920 211,920 Samsung investment—Investment Pool for Public funds 1(*5) — — 53,220 53,212 53,212 Korea investment—Hanwha KT Master Lease Private Special Investment Trust(*5) — — 30,560 30,568 30,568 Hwan Young Steel Co., Ltd. 10,916 0.14 % 1,092 97 — SAMBO AUTO. Co., Ltd. 15,066 0.02 % 38 38 — Mobo Co., Ltd. 504 0.00 % 14 14 — HANKOOK Silicon Co., Ltd. 3,005,208 10.44 % 7,513 1,495 — Dae Kwang Semiconductor Co., Ltd. 589 0.07 % 6 6 — Sanbon Department Store 828 0.01 % 124 3 — Miju Steel Mfg. Co., Ltd. 99,804 0.23 % 51 51 — BnB Sungwon Co., Ltd. 589 0.07 % 15 15 — Hana Civil Engineering Co., Ltd. 23 0.00 % 1 1 — KC Development Co., Ltd. 839 0.02 % 6 6 — IMHWA Corp. 329 0.11 % 5 5 — DALIM Special Vehicle Co., Ltd. 58 0.08 % 10 10 — ASA JEONJU Co., Ltd. 34,846 1.34 % 697 69 — Moonkyung Silica Co., Ltd. 42 0.56 % — — — Sungkwang Timber Co., Ltd. 9 0.34 % 4 4 — Yongbo Co., Ltd. 61 0.20 % 3 3 — HJ Steel Co., Ltd. 218 0.07 % 2 2 — KS Remicon Co., Ltd. 12 0.04 % 3 3 — SIN-E 109 0.08 % 33 33 — Joongang Platec Co., Ltd. 3,591 0.75 % 72 35 — Pyungsan SI Ltd. 434 0.01 % 9 9 — Samgong Development Co., Ltd. 12 0.01 % 7 7 — Joongang Development Co., Ltd. 540 0.12 % 8 8 — AJS Co., Ltd. 12,906 0.23 % 32 32 — SHIN-E 119 0.13 % 10 10 — MSE Co., Ltd. 429 0.13 % 9 9 — Ilrim Nano Tec Co., Ltd. 1,520 0.07 % 15 15 — Youngjin Hi-Tech 2,512 0.25 % 126 21 — Dong Woo International Co., Ltd. 90 0.37 % 18 18 — Buyoung Co., Ltd. 270 0.00 % 3 3 — Ilsuk Co., Ltd. 152 0.17 % 10 10 — Dongyang Telecom Co., Ltd. 1,760 0.01 % 11 11 — Han Young Construction Co., Ltd. 35 0.03 % 3 3 — Jongwon Remicon Co., Ltd. 31 0.18 % 13 13 — Ace Heat Treating Co., Ltd. 477 1.43 % 72 72 — Zyle Daewoo Motor Sales Co., Ltd. 22 0.00 % — — — Daewoo Development Co., Ltd. 8 0.00 % — — — Seyang Inc. 537 0.05 % 27 27 — Seungri Enterprise Co., Ltd. 93 0.05 % 3 3 — Onggane Food Co., Ltd 5 0.07 % 1 1 — Shin-E 12 0.00 % 1 1 — Ejung Ad Co., Ltd. 132 0.09 % 3 3 — Solvus Co., Ltd. 1,056 0.04 % 3 3 — Myung Co., Ltd. 89 0.05 % 2 2 — Emotion Co., Ltd. 167 0.61 % 8 8 — Youngdong Concrete Co., Ltd. 32 0.32 % 7 7 — 2016 Shares Ownership Acquisition Book value Fair value In millions of won Shinil Engineering Co., Ltd. 887 0.06 % ￦ 3 3 — Biwang Industry Co., Ltd 406 0.04 % 2 2 — Huimun Co., Ltd. 263 0.26 % 4 4 — Young Sung Co., Ltd. 89 0.40 % 27 27 — Yuil Industrial Electronics Co., Ltd. 804 0.32 % 16 16 — DN TEK Inc. 12,401 0.29 % 62 6 — Daeyang F.M.S Corporation 593 0.40 % 23 23 — Kwang Jin Structure Co., Ltd. 3,072 0.60 % 31 31 — Woojin Industry Corporation 3 0.00 % 16 16 — Kwang Sung Industry Co., Ltd. 325 0.35 % 7 7 — Futech Mold Co., Ltd. 274 0.27 % 14 14 — Samcheonri Industrial Co., Ltd. 533 0.98 % 13 13 — Woojoo Environment Ind. Co., Ltd. 101 0.11 % 13 13 — Cheongatti Co., Ltd. 57 0.10 % 4 4 — Hyungji Esquire Co., Ltd. 55 0.02 % 22 22 — Kolmar Pharma Co., Ltd. 1,426 0.01 % 52 3 — Morado Co., Ltd. 209 0.04 % 2 2 — Myung Sung Tex Co., Ltd. 20 0.00 % 2 2 — Kwang Sung Co., Ltd. 610 0.53 % 31 31 — EverTechno. Co.,Ltd. 29,424 0.73 % 147 7 — Autowel Co.,Ltd. 260 0.38 % 13 13 — Woobang Construction Co., Ltd. 8 0.00 % 8 8 — Shin Pyung Co., Ltd. 6 0.03 % 3 3 — JMC Heavy Industries Co., Ltd. 2,724 0.10 % 27 27 — Najin Steel Co., Ltd. 37 0.06 % 5 5 — Sinkwang Industry Co., Ltd. 1,091 1.68 % 5 5 — Join Land Co., Ltd. 33 0.00 % 1 1 — Crystal Co., Ltd. 22 0.07 % 2 2 — Elephant & Friends Co., Ltd. 563 0.61 % 3 3 — Mireco Co., Ltd. 109 0.25 % 11 11 — L&K Industry Co., Ltd. 1,615 0.60 % 24 24 — JO Tech Co., Ltd. 1,263 0.62 % 25 25 — Kendae Printing Co., Ltd. 422 0.60 % 21 21 — Dauning Co., Ltd. 231 0.41 % 6 6 — Korea Trecision Co., Ltd. 22 0.45 % 5 5 — Ace Track Co., Ltd. 3,130 1.08 % 219 59 — Taebok Machinery Co., Ltd. 109 1.08 % 11 11 — Yooah Industry Co., Ltd. 130 0.02 % 13 13 — Yoo-A 105 0.20 % 11 11 — Dung Hwan Co., Ltd. 531 0.02 % 5 5 — Hurim Biocell Co., Ltd. 113 0.00 % 5 5 — P. J, Trading Co., Ltd. 12 0.04 % — — — Sunjin Power Tech Co., Ltd. 4,941 0.92 % 247 90 — Smart Power Co.,Ltd. 133,333 5.55 % 200 200 — Haseung Industries Co.,Ltd. 55 0.62 % 28 28 — Beer Yeast Korea Inc. 1,388 0.43 % 7 7 — Daeryung Corporation 207 0.19 % 10 10 — Korea Bio Red Ginseng Co.,Ltd. 194 0.09 % 10 10 — ENH Co.,Ltd. 1,086 0.19 % 54 54 — OCO Co.,Ltd. 123 0.37 % 11 11 — B CON Co.,Ltd. 96 1.16 % 6 6 — Chunil Metal Co., Ltd. 11 0.15 % 4 4 — Teakwang Tech Co., Ltd. 2,460 0.11 % 12 12 — 2016 Shares Ownership Acquisition Book value Fair value In millions of won SsangMa Machine Co., Ltd. 4 0.05 % ￦ 1 1 — SinJin Co., Ltd. 233 0.30 % 9 9 — Ace Integration Co., Ltd 93 0.09 % 21 21 — AceInti Agricultural Co., Ltd. 3 0.00 % 1 1 — KyungDong Co., Ltd. 130 0.01 % 1 1 — ChunWon Development Co., Ltd. 193 0.19 % 39 39 — WonIl Co., Ltd. 999 0.15 % 50 50 — SungLim Industrial Co., Ltd. 29 0.03 % 1 1 — DaeHa Co., Ltd. 141 0.54 % 11 11 — Korea Minerals Co., Ltd. 191 0.05 % 135 135 — HyoDong Development Co., Ltd. 119 0.15 % 24 24 — Haspe Tech Co., Ltd. 652 0.55 % 20 20 — JoHyun Co., Ltd. 350 1.56 % 18 18 — KC Co., Ltd. 5,107 0.17 % 3 3 — SeongJi Industrial Co.,Ltd. 41 0.05 % 1 1 — AREVA NC Expansion 1,077,124 13.49 % 288,443 98,472 98,472 Navanakorn Electric Co., Ltd.(*3) 8,885,600 26.93 % 17,216 18,509 — PT. Kedap Saayq 671 10.00 % 18,540 — — Set Holding(*4) 1,100,220 2.50 % 229,255 170,170 170,170 PT. Cirebon Energi Prasarana 22,420 10.00 % 2,612 2,709 — 1,040,553 746,561 706,476 ￦ 1,406,326 1,014,732 974,647 (*1) Investments in unlisted equity securities held by the Company for which a quoted market price does not exist in an active market and fair value cannot be measured reliably were measured at cost less impairment, if any. (*2) The Company has estimated the fair value of the investment in Construction Guarantee based upon the price which would be applied when the investment is returned. The Company has recognized the difference between its fair value and book value as a gain or loss on valuation of available-for-sale (*3) Although the Company holds more than 20% of the equity shares of these investments, the Company cannot exercise significant influence. (*4) The Company has estimated the fair value of Set Holding by using the discounted cash flow method and has recognized the difference between its fair value and book value as gain or loss on valuation of available-for-sale (*5) As of December 31, 2016, the Company invested in ￦437,015 million as beneficiary securities exclusively for payment of decommissioning cost of nuclear power plants. The Company has measured the fair value of the beneficiary securities based on its net asset value. (*6) The number of shares owned has changed due to the stock merge (500:1) during the year ended December 31, 2016 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won Listed Korea District Heating Corp. 2,264,068 19.55% ￦ 173,201 165,277 165,277 Ssangyong Motor Co., Ltd. 38,568 0.03% 428 197 197 Sungjee Construction. Co., Ltd. 10,530 0.01% 49 8 8 Korea Line Corp. 18 0.00% 1 — — Namkwang Engineering & Construction Co., Ltd. 46 0.00% 15 — — Pumyang Construction Co., Ltd.(*7) 35 0.00% 2 — — ELCOMTEC Co., Ltd. 32,875 0.04% 217 72 72 PAN ocean Co., Ltd. 1,492 0.00% 14 8 8 Dongbu Corporation(*6) 955 0.02% 12 10 10 KSP Co., Ltd. 6,324 0.08% 24 24 24 STX Heavy Industries Co., Ltd. 35,749 0.14% 191 165 165 PT Adaro Energy Tbk 480,000,000 1.50% 71,554 70,531 70,531 Energy Fuels Inc. 1,711,814 2.38% 16,819 3,300 3,300 Baralaba Coal Company Limited 99,763 0.07% 18,445 22 22 Denison Mines Corp. 58,284,000 10.42% 84,134 34,292 34,292 Fission 3.0 300,000 0.14% — 15 15 Fission Uranium Corp. 800,000 0.16% 785 532 532 365,891 274,453 274,453 Unlisted Korea investment—Korea EXIM Bank CERs Private Special Asset Investment Trust I 1,758,731,002 14.18% 1,752 571 — Troika Overseas Resource Development Private Equity Firm 13,340,012,100 3.66% 13,340 1,553 — IBK-AUCTUS 152 6.29% 41 41 — Global Dynasty Overseas Resource Development Private Equity Firm 2,242,437,289 7.46% 2,242 2,242 — Intellectual Discovery, Ltd. 1,000,000 8.81% 5,000 954 — Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 4,176,751,013 5.00% 4,328 4,328 — Construction Guarantee(*2) 571 0.02% 601 833 833 Plant & Mechanical Contractors Financial Cooperative of Korea 144 0.03% 126 126 — Fire Guarantee 40 0.01% 20 20 — Korea Software Financial Cooperative 5,186 1.09% 3,301 3,301 — Engineering Financial Cooperative 486 0.05% 60 60 — Electric Contractors Financial Cooperative 1,000 0.04% 216 216 — Korea Specialty Contractor Financial Cooperative 476 0.01% 417 417 — Information & Communication Financial Cooperative 121 0.02% 26 26 — Korea Electric Engineers Association 400 0.24% 40 40 — Samsung investment—Investment Pool for Public funds 1(*5) — — 53,220 53,739 53,739 Korea investment—Hanwha KT Master Lease Private Special Investment Trust(*5) — — 26,586 26,591 26,591 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won Kyobo Royal-Class Repo Plus Fixed Income 1Y 2nd (*5) — — ￦ 33,000 33,008 33,008 Kyobo Royal-Class Repo Plus Fixed Income 2Y 1st (*5) — — 50,000 50,399 50,399 Kyobo Royal-Class Repo Plus A1 ABCP 1Y (*5) — — 50,000 50,419 50,419 Hwan Young Steel Co., Ltd. 10,916 0.14% 1,092 97 — SAMBO AUTO. Co., Ltd. 15,066 0.02% 38 38 — Mobo Co., Ltd. 504 0.00% 14 14 — Dae Kwang Semiconductor Co., Ltd. 589 0.07% 6 6 — Sanbon Department Store 828 0.01% 124 3 — Miju Steel Mfg. Co., Ltd. 99,804 0.23% 50 50 — Sungwon Co., Ltd. (formerly, BnB Sungwon Co., Ltd.) 589 0.07% 15 15 — Hana Civil Engineering Co., Ltd. 23 0.00% 1 1 — KC Development Co., Ltd. 839 0.02% 6 6 — IMHWA Corp. 329 0.11% 5 5 — DALIM Special Vehicle Co., Ltd. 58 0.08% 10 10 — ASA JEONJU Co., Ltd. 34,846 1.34% 697 69 — Moonkyung Silica Co., Ltd. 42 0.56% — — — Sungkwang Timber Co., Ltd. 9 0.34% 4 4 — Yongbo Co., Ltd. 61 0.20% 3 3 — HJ Steel Co., Ltd. 218 0.07% 2 2 — KS Remicon Co., Ltd. 12 0.04% 3 3 — Joongang Platec Co., Ltd. 3,591 0.75% 72 35 — Pyungsan SI Ltd. 434 0.01% 9 9 — Samgong Development Co., Ltd. 12 0.01% 7 7 — Joongang Development Co., Ltd. 540 0.12% 8 8 — AJS Co., Ltd. 12,906 0.23% 32 32 — SHIN-E 119 0.13% 10 10 — MSE Co., Ltd. 429 0.13% 9 9 — Ilrim Nano Tec Co., Ltd. 1,520 0.07% 15 15 — Youngjin Hi-Tech 2,512 0.25% 126 21 — Buyoung Co., Ltd. 270 0.00% 3 3 — Ilsuk Co., Ltd. 152 0.17% 10 10 — Dongyang Telecom Co., Ltd. 1,760 0.01% 11 11 — Jongwon Remicon Co., Ltd. 31 0.18% 13 13 — Ace Heat Treating Co., Ltd. 477 1.43% 72 72 — Zyle Daewoo Motor Sales Co., Ltd. 22 0.00% — — — Daewoo Development Co., Ltd. 8 0.00% — — — Seyang Inc. 537 0.05% 27 27 — Seungri Enterprise Co., Ltd. 93 0.05% 3 3 — Onggane Food Co., Ltd 5 0.07% 1 1 — Shin-E 12 0.00% 1 1 — Ejung Ad Co., Ltd. 132 0.09% 3 3 — Solvus Co., Ltd. 1,056 0.04% 3 3 — Myung Co., Ltd. 89 0.05% 2 2 — Shinil Engineering Co., Ltd. 887 0.06% 3 3 — Biwang Industry Co., Ltd 406 0.04% 2 2 — Huimun Co., Ltd. 263 0.26% 4 4 — Young Sung Co., Ltd. 89 0.40% 26 26 — Yuil Industrial Electronics Co., Ltd. 804 0.32% 15 15 — DN TEK Inc. 12,401 0.29% 61 5 — 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won Kwang Jin Structure Co., Ltd. 3,072 0.60% ￦ 31 31 — Woojin Industry Corporation 3 0.00% 16 16 — Kwang Sung Industry Co., Ltd. 325 0.35% 7 7 — Futech Mold Co., Ltd. 274 0.27% 14 14 — Woojoo Environment Ind. Co., Ltd. 101 0.11% 13 13 — Cheongatti Co., Ltd. 57 0.10% 4 4 — Hyungji Esquire Co., Ltd. 55 0.02% 22 22 — Kolmar Pharma Co., Ltd. 1,426 0.01% 52 3 — Morado Co., Ltd. 209 0.04% 2 2 — Myung Sung Tex Co., Ltd. 20 0.00% 2 2 — Kwang Sung Co., Ltd. 610 0.53% 31 31 — EverTechno. Co.,Ltd. 29,424 0.73% 148 7 — Autowel Co.,Ltd. 260 0.38% 14 14 — Woobang Construction Co., Ltd. 8 0.00% 8 8 — Shin Pyung Co., Ltd. 6 0.03% 3 3 — JMC Heavy Industries Co., Ltd. 2,724 0.10% 27 27 — Najin Steel Co., Ltd. 37 0.06% 5 5 — Sinkwang Industry Co., Ltd. 1,091 1.68% 5 5 — Crystal Co., Ltd. 22 0.07% 2 2 — Elephant & Friends Co., Ltd. 563 0.61% 3 3 — Mireco Co., Ltd. 109 0.25% 11 11 — L&K Industry Co., Ltd. 1,615 0.60% 24 24 — JO Tech Co., Ltd. 1,263 0.62% 25 25 — Kendae Printing Co., Ltd. 422 0.60% 21 21 — Dauning Co., Ltd. 231 0.41% 6 6 — Korea Trecision Co., Ltd. 22 0.45% 5 5 — Ace Track Co., Ltd. 3,130 1.08% 219 59 — Taebok Machinery Co., Ltd. 109 1.08% 11 11 — Yoo-A 105 0.20% 11 11 — Dung Hwan Co., Ltd. 531 0.02% 5 5 — Hurim Biocell Co., Ltd. 113 0.00% 5 5 — Sunjin Power Tech Co., Ltd. 4,941 0.92% 247 32 — Smart Power Co.,Ltd. 133,333 4.83% 200 200 — Haseung Industries Co.,Ltd. 55 0.62% 28 28 — Beer Yeast Korea Inc. 1,388 0.43% 7 7 — Daeryung Corporation 207 0.19% 10 10 — Korea Bio Red Ginseng Co.,Ltd. 194 0.09% 10 10 — ENH Co.,Ltd. 1,086 0.19% 54 54 — B CON Co.,Ltd. 96 1.16% 6 6 — Chunil Metal Co.,Ltd. 11 0.15% 4 4 — SsangMa Machine Co., Ltd. 4 0.05% 1 1 — SinJin Co., Ltd. 233 0.30% 9 9 — Ace Integration Co., Ltd 105 0.09% 24 24 — AceInti Agricultural Co., Ltd. 16 0.02% 5 5 — KyungDong Co., Ltd. 130 0.01% 1 1 — ChunWon Development Co., Ltd. 193 0.19% 39 39 — WonIl Co., Ltd. 999 0.15% 50 50 — SungLim Industrial Co., Ltd. 29 0.03% 1 1 — Korea Minerals Co., Ltd. 191 0.05% 134 1 — HyoDong Development Co., Ltd. 119 0.15% 24 24 — Haspe Tech Co., Ltd. 652 0.55% 20 20 — JoHyun Co., Ltd. 350 1.56% 18 18 — KC Co., Ltd. 5,107 0.17% 3 3 — SeongJi Industrial Co.,Ltd. 41 0.05% 1 1 — 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won DongKwang SD, Inc. 524 0.23% ￦ 13 13 — Dong Yang Metal Co., Ltd. 2,951 1.97% 15 15 — Seyang Precision Ind. Co., Ltd. 829 0.23% 41 41 — Dooriwon Food System Co., Ltd. 13 0.27% 1 1 — ShinShin Co., Ltd 339 1.12% 17 17 — Kitorang Co., Ltd. 165 0.24% 49 49 — Sung Kwang Co., Ltd. 23 0.37% 6 6 — Hyundai Metal Co., Ltd. 3,757 5.60% 1,416 1,416 — Shinheung petrol. Co. Ltd. 699 0.14% 7 7 — Force TEC Co., Ltd. 3,501 0.02% 18 18 — Haisung Industrial Systems Co., Ltd. 10,751 0.24% 54 54 — Samsung Tech Co., Ltd. 486 1.28% 97 97 — Tae Hyung Co., Ltd. 28 0.43% 20 20 — Samyangplant Co., Ltd. 323 0.60% 16 16 — Younil Metal Co., Ltd. 41 0.21% 21 21 — Myungjin Tech Co., Ltd. 20 0.54% 4 4 — Hankook Machine Tools Co., Ltd. 719 0.14% 72 72 — Hankook Precision Ind Co., Ltd. 110 0.06% 11 11 — Borneo International Furniture Co., Ltd. 64,037 0.28% 97 14 — CJ Paradise Co.,Ltd 24 0.02% 12 12 — Han Young Technology Company Co.,Ltd. 35 0.00% — — — Jungdo Aluminium Co.,Ltd. 8,527 0.35% 128 128 — Ilheung Metal Co, Ltd. 280 0.83% 28 28 — STX Offshore & Shipbuilding Co., Ltd 8,622 0.25% 1,078 1,078 — Ptotronics Co., Ltd. 151 0.07% 2 2 — NFT Co., Ltd. 136 0.40% 8 8 — Echoroba Co.,Ltd. 157 0.02% 3 3 — Hyundaitech Co.,Ltd. 1,363 0.87% 27 27 — Eco Alux Co.,Ltd. 239 0.22% 48 48 — Daekyung Industry Co.,Ltd. 9,112 0.94% 13 13 — Dasan Material Co.Ltd. 29 0.04% — — — Fish World Co.,Ltd. 47 0.21% 2 2 — SG Shinsung Engineering and Construction Co., Ltd. 10 0.00% 6 6 — Samdo Industry Electric Co.,Ltd. 48 0.02% 1 1 — Taejung Industries Co.,Ltd. 9,268 0.30% 5 5 — Shinsei Trading Co., Ltd. 64 0.72% 1 1 — Dynamic Co., Ltd. 111 0.19% 3 3 — Green Alchemy Co.,Ltd. 38,202 1.48% 191 191 — IQ Power Asia Inc. 16,179 0.31% 81 81 — Youone TBM Engineering & Construction Co., Ltd. 227,854 0.27% 31 31 — KM Leatech 1,648 0.98% 8 8 — Wonil T&I Co., Ltd. 229 0.17% 23 23 — Semist Co.,Ltd. 555 0.80% 3 3 — DS POWER Co., Ltd.(*8) 580,000 2.34% 2,900 1,223 1,223 Navanakorn Electric Co., Ltd.(*3) 4,442,800 26.93% 17,216 16,410 — PT. Kedap Saayq 671 10.00% 18,540 — — Set Holding(*4) 1,100,220 2.50% 229,255 171,242 171,242 PT. Cirebon Energi Prasarana 22,420 10.00% 2,612 2,401 — 522,782 425,380 387,454 ￦ 888,673 699,833 661,907 (*1) Investments in unlisted equity securities held by the Company for which a quoted market price does not exist in an active market and fair value cannot be measured reliably were measured at cost less impairment, if any. (*2) The Company has estimated the fair value of the investment in Construction Guarantee based upon the price which would be applied when the investment is returned. The Company has recognized the difference between its fair value and book value as a gain or loss on valuation of available-for-sale (*3) Although the Company holds more than 20% of the equity shares of these investments, the Company cannot exercise significant influence. (*4) The Company has estimated the fair value of Set Holding by using the discounted cash flow method and has recognized the difference between its fair value and book value as gain or loss on valuation of available-for-sale (*5) As of December 31, 2017, the Company invested in ￦285,769 million as beneficiary securities exclusively for payment of decommissioning cost of nuclear power plants. The Company has measured the fair value of the beneficiary securities based on its net asset value. (*6) The number of shares owned has changed due to the stock merge (9:7) during the year ended December 31, 2017. (*7) The number of shares increased due to the stock split (5:1). (*8) As described in note 17, this is reclassified to available-for-sale

Held-to-maturity Investments

Held-to-maturity Investments	12 Months Ended
	Dec. 31, 2017
Held-to-maturity Investments [Abstract]
Held-to-maturity Investments	10. Held-to-maturity Held-to-maturity 2016 Beginning balance Acquisition Disposal Others Ending balance In millions of won Government bonds ￦ 3,623 149 (528 ) — 3,244 ￦ 3,623 149 (528 ) — 3,244 Current ￦ 380 — (380 ) 114 114 Non-current 3,243 149 (148 ) (114 ) 3,130 2017 Beginning balance Acquisition Disposal Others Ending balance In millions of won Government bonds ￦ 3,244 250 (350 ) — 3,144 ￦ 3,244 250 (350 ) — 3,144 Current ￦ 114 — (113 ) 4 5 Non-current 3,130 250 (237 ) (4 ) 3,139

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2017
Derivatives [Abstract]
Derivatives	11. Derivatives (1) Derivatives as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Derivative assets Currency forward ￦ 8,370 32,806 45 — Currency swap 184,913 540,057 12 15,711 Interest rate swap — 4,705 — 2,697 Others(*1) — 10,523 12,878 1,283 ￦ 193,283 588,091 12,935 19,691 Derivative liabilities Currency forward ￦ 1,153 34 7,862 1,278 Currency swap — 56,612 61,997 296,098 Interest rate swap 2,098 78,789 1,408 59,416 ￦ 3,251 135,435 71,267 356,792 (*1) The Company has a put option to sell shares of DS POWER Co., Ltd, a related party of the Company, and the fair value of the option is recorded in ‘Others’. (2) Currency forward contracts which are not designated as hedge instruments as of December 31, 2017 are as follows: Counterparty Contract Date Maturity date Contract amounts Contract exchange rate Pay Receive In millions of won and thousands of foreign currencies KEB Hana Bank 2014.04.10 2021.07.12 55,120 USD 52,000 1,060.00 KEB Hana Bank 2014.04.28 2021.07.12 50,784 USD 48,000 1,058.00 Bank of America 2014.04.29 2021.07.12 105,400 USD 100,000 1,054.00 KEB Hana Bank 2014.05.09 2021.07.12 104,600 USD 100,000 1,046.00 KEB Hana Bank 2017.12.22 2021.07.12 105,079 USD 100,000 1,050.79 Korea Development Bank 2017.12.27 2021.07.12 104,849 USD 100,000 1,048.49 CCB 2017.12.07 2018.01.11 10,921 USD 10,000 1,092.14 Morgan Stanley 2017.11.27 2018.01.03 5,439 USD 5,000 1,087.70 Mizuho Bank 2017.11.29 2018.01.05 5,402 USD 5,000 1,080.32 KEB Hana Bank 2017.11.30 2018.01.08 5,437 USD 5,000 1,087.35 Mizuho Bank 2017.12.05 2018.01.09 5,416 USD 5,000 1,083.20 Nova Scotia 2017.12.11 2018.01.12 10,922 USD 10,000 1,092.20 Kookmin Bank 2017.12.12 2018.01.15 3,270 USD 3,000 1,090.15 Kookmin Bank 2017.12.13 2018.01.16 10,906 USD 10,000 1,090.55 Credit Suisse 2017.12.14 2018.01.17 10,858 USD 10,000 1,085.80 Standard Chartered 2017.12.14 2018.01.18 10,858 USD 10,000 1,085.80 Morgan Stanley 2017.12.15 2018.01.19 10,884 USD 10,000 1,088.39 Nova Scotia 2017.12.18 2018.01.22 10,881 USD 10,000 1,088.14 Standard Chartered 2017.12.20 2018.01.22 5,413 USD 5,000 1,082.60 Mizuho Bank 2017.12.21 2018.01.26 10,802 USD 10,000 1,080.20 Credit Suisse 2017.12.22 2018.01.26 10,778 USD 10,000 1,077.75 KEB Hana Bank 2017.12.28 2018.01.29 10,716 USD 10,000 1,071.55 CCB 2017.12.28 2018.01.30 10,706 USD 10,000 1,070.60 Nova Scotia 2017.12.29 2018.02.05 10,679 USD 10,000 1,067.90 Nova Scotia 2017.12.05 2018.01.05 2,170 USD 2,000 1,084.92 Nova Scotia 2017.12.05 2018.01.05 2,164 USD 2,000 1,082.02 Nova Scotia 2017.12.07 2018.01.05 6,551 USD 6,000 1,091.77 Korea Development Bank 2017.12.14 2018.01.10 11,950 USD 11,000 1,086.35 Societe Generale 2017.12.14 2018.01.10 10,865 USD 10,000 1,086.45 BTMU 2017.12.20 2018.01.16 11,906 USD 11,000 1,082.35 Korea Development Bank 2017.12.20 2018.01.16 15,130 USD 14,000 1,080.70 CCB 2017.12.21 2018.01.23 11,880 USD 11,000 1,080.00 Korea Development Bank 2017.12.28 2018.01.31 11,782 USD 11,000 1,071.10 Nova Scotia 2017.12.28 2018.01.23 33,209 USD 31,000 1,071.25 KEB Hana Bank 2017.12.28 2018.01.23 10,712 USD 10,000 1,071.15 BTMU 2017.12.28 2018.01.31 10,712 USD 10,000 1,071.20 BNP Paribas 2017.11.15 2018.01.17 3,713 USD 3,349 1,108.60 Nova Scotia 2017.11.15 2018.01.22 8,837 USD 8,000 1,104.60 BTMU 2017.11.29 2018.02.01 7,568 USD 7,000 1,081.20 BNP Paribas 2017.11.29 2018.02.01 7,557 USD 7,000 1,079.60 Credit Agricole 2017.12.19 2018.01.22 5,429 USD 5,000 1,085.75 BTMU 2017.12.20 2018.02.22 10,822 USD 10,000 1,082.18 KEB Hana Bank 2017.12.20 2018.01.22 2,879 USD 2,661 1,082.00 BNP Paribas 2017.12.20 2018.01.22 5,406 USD 5,000 1,081.10 Nonghyup Bank 2017.12.21 2018.01.23 6,467 USD 6,000 1,077.90 Nova Scotia 2017.12.27 2018.01.29 5,366 USD 5,000 1,073.15 Nova Scotia 2017.12.27 2018.01.05 5,373 USD 5,000 1,074.50 KEB Hana Bank 2017.11.23 2018.01.11 9,237 USD 8,500 1,086.76 Standard Chartered 2017.12.13 2018.01.15 5,454 USD 5,000 1,090.70 Standard Chartered 2017.12.08 2018.01.25 10,921 USD 10,000 1,092.05 Standard Chartered 2017.10.31 2018.02.21 5,610 USD 5,000 1,122.00 Standard Chartered 2017.11.29 2018.02.21 7,572 USD 7,000 1,081.65 Nova Scotia 2017.12.20 2018.03.22 3,978 USD 3,682 1,080.55 Nova Scotia 2017.12.20 2018.03.22 5,399 USD 5,000 1,079.75 Nova Scotia 2017.12.20 2018.03.22 5,393 USD 5,000 1,078.55 Nova Scotia 2017.12.20 2018.03.22 5,393 USD 5,000 1,078.65 Nova Scotia 2017.12.14 2018.03.19 205 USD 189 1,084.50 Standard Chartered 2017.12.19 2018.03.21 3,164 USD 2,918 1,084.20 Societe Generale 2017.12.19 2018.03.21 1,177 USD 1,087 1,082.90 Societe Generale 2017.12.19 2018.03.21 5,418 USD 5,000 1,083.60 Societe Generale 2017.12.19 2018.03.21 5,421 USD 5,000 1,084.20 BNP Paribas 2017.12.19 2018.03.21 5,413 USD 5,000 1,082.60 BNP Paribas 2017.12.19 2018.03.21 5,419 USD 5,000 1,083.70 BNP Paribas 2017.12.19 2018.03.21 5,422 USD 5,000 1,084.30 Nova Scotia 2017.12.19 2018.03.21 5,427 USD 5,000 1,085.40 Nova Scotia 2017.12.19 2018.03.21 5,430 USD 5,000 1,085.90 Nova Scotia 2017.12.14 2018.03.19 5,428 USD 5,000 1,085.50 Standard Chartered 2017.12.14 2018.03.19 5,428 USD 5,000 1,085.50 Nova Scotia 2017.11.21 2018.02.26 5,266 USD 4,826 1,091.10 Nova Scotia 2017.11.21 2018.02.26 5,461 USD 5,000 1,092.10 Nova Scotia 2017.11.15 2018.02.21 1,755 USD 1,587 1,106.10 Nova Scotia 2017.11.15 2018.02.21 5,536 USD 5,000 1,107.10 Nova Scotia 2017.11.15 2018.02.21 4,462 USD 4,027 1,108.10 Nova Scotia 2017.10.31 2018.02.06 711 USD 638 1,112.80 Nova Scotia 2017.10.31 2018.02.05 194 USD 173 1,117.80 Nova Scotia 2017.10.31 2018.02.05 5,594 USD 5,000 1,118.80 Nova Scotia 2017.10.31 2018.02.02 5,604 USD 5,000 1,120.80 Nova Scotia 2017.10.31 2018.02.02 5,599 USD 5,000 1,119.80 Nomura 2017.10.31 2018.02.02 5,602 USD 5,000 1,120.40 Credit Agricole 2017.10.31 2018.02.02 5,604 USD 5,000 1,120.70 Credit Agricole 2017.10.31 2018.02.02 5,599 USD 5,000 1,119.70 Standard Chartered 2017.10.31 2018.02.02 5,604 USD 5,000 1,120.70 Standard Chartered 2017.10.31 2018.02.02 5,393 USD 4,817 1,119.70 Societe Generale 2017.10.31 2018.02.02 861 USD 768 1,120.80 Nova Scotia 2017.10.26 2018.01.30 923 USD 822 1,123.40 BNP Paribas 2017.10.13 2018.01.18 652 USD 579 1,125.60 KEB Hana Bank 2017.11.27 2018.11.26 JPY 40,000 398 9.94 (3) Currency swap contracts which are not designated as hedge instruments as of December 31, 2017 are as follows: Counterparty Contract Contract amount Contract interest rate Contract Pay Receive Pay Receive In millions of won and thousands of foreign currencies Deutsche Bank 2013~2018 110,412 JPY 10,000,000 6.21% 4.19% 11.04 IBK 2013~2018 111,800 USD 100,000 3.16% 2.79% 1,118.00 Bank of America 2013~2018 103,580 JPY 10,000,000 7.05% 4.19% 10.36 Credit Suisse 2014~2019 118,632 CHF 100,000 2.98% 1.50% 1,186.32 Standard Chartered 2014~2019 114,903 CHF 100,000 4.00% 1.50% 1,149.03 Standard Chartered 2014~2029 102,470 USD 100,000 3.14% 3.57% 1,024.70 Societe Generale 2014~2024 105,017 USD 100,000 4.92% 5.13% 1,050.17 KEB Hana Bank 2015~2024 107,970 USD 100,000 4.75% 5.13% 1,079.70 Credit Agricole 2015~2024 94,219 USD 86,920 4.85% 5.13% 1,083.97 Citibank 2012~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 JP Morgan 2012~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 Bank of America 2012~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 Shinhan Bank 2016~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 HSBC 2012~2022 111,770 USD 100,000 2.89% 3.00% 1,117.70 KEB Hana Bank 2012~2022 111,770 USD 100,000 2.87% 3.00% 1,117.70 Standard Chartered 2012~2022 111,770 USD 100,000 2.89% 3.00% 1,117.70 Deutsche Bank 2012~2022 55,885 USD 50,000 2.79% 3.00% 1,117.70 DBS 2013~2018 108,140 USD 100,000 2.63% 3M Libor+0.84% 1,081.40 DBS 2013~2018 108,140 USD 100,000 2.57% 3M Libor+0.84% 1,081.40 DBS 2013~2018 108,140 USD 100,000 2.57% 3M Libor+0.84% 1,081.40 HSBC 2013~2018 107,450 USD 100,000 3.41% 2.88% 1,074.50 Standard Chartered 2013~2018 107,450 USD 100,000 3.44% 2.88% 1,074.50 JP Morgan 2013~2018 107,450 USD 100,000 3.48% 2.88% 1,074.50 Bank of America 2014~2018 107,450 USD 100,000 3.09% 2.88% 1,074.50 Citibank 2014~2018 107,450 USD 100,000 3.09% 2.88% 1,074.50 HSBC 2014~2019 105,260 USD 100,000 2.48% 2.38% 1,052.60 Standard Chartered 2014~2019 105,260 USD 100,000 2.48% 2.38% 1,052.60 Korea Development Bank 2016~2019 105,260 USD 100,000 2.48% 2.38% 1,052.60 Nomura 2015~2025 111,190 USD 100,000 2.60% 3.25% 1,111.90 Korea Development Bank 2015~2025 111,190 USD 100,000 2.62% 3.25% 1,111.90 Woori Bank 2015~2025 55,595 USD 50,000 2.62% 3.25% 1,111.90 KEB Hana Bank 2015~2025 55,595 USD 50,000 2.62% 3.25% 1,111.90 Woori Bank 2017~2027 111,610 USD 100,000 2.25% 3.13% 1,116.10 KEB Hana Bank 2017~2027 111,610 USD 100,000 2.31% 3.13% 1,116.10 Korea Development Bank 2017~2027 111,610 USD 100,000 2.31% 3.13% 1,116.10 (4) Currency swap contracts which are designated as hedge instruments as of December 31, 2017 are as follows: Counterparty Contract year Contract amount Contract interest rate Contract rate Pay Receive Pay Receive In millions of won and thousands of foreign currencies Citibank 2013~2018 54,570 USD 50,000 2.90% 3M Libor+1.01% 1,091.40 Standard Chartered 2013~2018 54,570 USD 50,000 2.90% 3M Libor+1.01% 1,091.40 Credit Suisse 2013~2018 111,410 USD 100,000 3.22% 3M Libor+1.50% 1,114.10 HSBC 2014~2020 99,901 AUD 100,000 3.52% 5.75% 999.01 HSBC 2014~2020 100,482 AUD 100,000 3.48% 5.75% 1,004.82 Standard Chartered 2013~2020 USD 117,250 AUD 125,000 3M Libor+1.25% 5.75% 0.94 Standard Chartered 2014~2020 126,032 USD 117,250 3.55% 3M Libor+1.25% 1,074.90 Korea Development Bank 2017~2020 114,580 USD 100,000 1.75% 2.38% 1,145.80 KEB Hana Bank 2017~2020 114,580 USD 100,000 1.75% 2.38% 1,145.80 Export-import bank of Korea 2017~2020 114,580 USD 100,000 1.75% 2.38% 1,145.80 JP Morgan 2014~2019 107,190 USD 100,000 3M Libor+3.25% 2.75% 1,071.90 Morgan Stanley 2014~2019 107,190 USD 100,000 3M Libor+3.25% 2.75% 1,071.90 Deutsche Bank 2014~2019 107,190 USD 100,000 3M Libor+3.25% 2.75% 1,071.90 Korea Development Bank 2016~2021 121,000 USD 100,000 2.15% 2.50% 1,210.00 Morgan Stanley 2016~2021 121,000 USD 100,000 3M Libor+2.10% 2.50% 1,210.00 BNP Paribas 2016~2021 121,000 USD 100,000 3M Libor+2.10% 2.50% 1,210.00 Nomura 2017~2037 52,457 EUR 40,000 2.60% 1.70% 1,311.42 Nomura 2017~2037 59,423 SEK 450,000 2.62% 2.36% 132.05 Credit Agricole 2013~2019 118,343 CHF 100,000 3.47% 1.63% 1,183.43 Morgan Stanley 2013~2019 59,172 CHF 50,000 3.40% 1.63% 1,183.43 Nomura 2013~2019 59,172 CHF 50,000 3.47% 1.63% 1,183.43 Morgan Stanley 2013~2018 107,360 USD 100,000 3.27% 2.88% 1,073.60 Credit Agricole 2013~2018 107,360 USD 100,000 3.34% 2.88% 1,073.60 JP Morgan 2013~2018 161,040 USD 150,000 3.34% 2.88% 1,073.60 Standard Chartered 2013~2018 161,040 USD 150,000 3.34% 2.88% 1,073.60 Standard Chartered 2014~2019 104,490 USD 100,000 2.77% 2.63% 1,044.90 Credit Agricole 2014~2019 104,490 USD 100,000 2.77% 2.63% 1,044.90 Morgan Stanley 2014~2019 104,490 USD 100,000 2.70% 2.63% 1,044.90 Standard Chartered 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Credit Agricole 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Deutsche Bank 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Citibank 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Societe Generale 2013~2018 106,190 USD 100,000 3.48% 2.63% 1,061.90 BNP Paribas 2013~2018 53,095 USD 50,000 3.48% 2.63% 1,061.90 KEB Hana Bank 2013~2018 53,095 USD 50,000 3.48% 2.63% 1,061.90 Standard Chartered 2013~2018 106,030 USD 100,000 3.48% 2.63% 1,060.30 BNP Paribas 2013~2018 53,015 USD 50,000 3.48% 2.63% 1,060.30 KEB Hana Bank 2013~2018 31,809 USD 30,000 3.48% 2.63% 1,060.30 Societe Generale 2013~2018 21,206 USD 20,000 3.48% 2.63% 1,060.30 HSBC 2013~2018 53,015 USD 50,000 3.47% 2.63% 1,060.30 Nomura 2013~2018 53,015 USD 50,000 3.47% 2.63% 1,060.30 Credit Agricole 2014~2020 110,680 USD 100,000 2.29% 2.50% 1,106.80 Societe Generale 2014~2020 55,340 USD 50,000 2.16% 2.50% 1,106.80 KEB Hana Bank 2014~2020 55,340 USD 50,000 2.16% 2.50% 1,106.80 KEB Hana Bank 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 Standard Chartered 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 HSBC 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 Nomura 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 BNP Paribas 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 HSBC 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 KEB Hana Bank 2017~2022 226,600 USD 200,000 1.94% 2.63% 1,133.00 Korea Development Bank 2017~2022 113,300 USD 100,000 1.94% 2.63% 1,133.00 Nomura 2017~2022 113,300 USD 100,000 1.95% 2.63% 1,133.00 Woori Bank 2017~2022 56,650 USD 50,000 1.95% 2.63% 1,133.00 Kookmin Bank 2017~2022 56,650 USD 50,000 1.95% 2.63% 1,133.00 (5) Interest rate swap contracts which are not designated as hedge instruments as of December 31, 2017 are as follows: Counterparty Contract Contract amount Contract interest rate per annum Pay Receive In millions of JP Morgan 2013~2018 ￦ 150,000 3.58% 3M CD+0.31% Credit Suisse 2014~2018 25,000 2.98% 1Y CMT+0.31% KEB Hana Bank 2017~2022 100,000 2.01% 3M CD+0.24% KEB Hana Bank 2017~2022 100,000 2.06% 3M CD+0.27% Nomura(*1) 2017~2037 30,000 2.05% 3.08% KEB Hana Bank 2017~2021 200,000 2.45% 3M CD+0.32% Export-import bank of Korea 2015~2031 USD 15,893 2.67% 6M USD Libor ING Bank 2015~2031 USD 7,861 2.67% 6M USD Libor BNP Paribas 2015~2031 USD 7,861 2.67% 6M USD Libor (*1) 2.05% of the contract interest rate for paying is applied for five years from the date of issuance, and 3M CD + 0.10% is applied thereafter. (6) Interest rate swap contracts which are designated as hedge instruments as of December 31, 2017 are as follows: Counterparty Contract Contract amount Contract interest rate per annum Pay Receive In millions of BNP Paribas 2009~2027 USD 92,120 4.16% 6M USD Libor KFW 2009~2027 USD 92,120 4.16% 6M USD Libor Credit Agricole 2016~2033 USD 96,297 3.98% ~ 4.10% 6M USD Libor SMBC 2016~2033 USD 125,927 4.05% ~ 4.18% 6M USD Libor Mizuho Bank 2016~2019 USD 36,890 1.56% 1.35% SMBC 2016~2019 USD 36,890 1.56% 1.35% (7) Gain and loss on valuation and transaction of derivatives for the years ended December 31, 2016 and 2017 are as follows and included in finance income and costs in the consolidated statements of comprehensive income (loss): Net income effects of valuation gain (loss) Net income effects of transaction gain (loss) Accumulated other comprehensive 2015 2016 2017 2015 2016 2017 2015 2016 2017 In millions of won Currency forward ￦ 357 15,993 (41,889 ) 8,523 4,266 (28,223 ) — — — Currency swap 431,565 253,035 (843,747 ) 75,752 (68,266 ) (137,376 ) (6,926 ) 40,031 26,810 Interest rate swap 161,609 8,517 6,909 30,314 7,562 (3,362 ) 4,082 6,719 5,074 Other derivatives — 10,523 4,060 — — — — — — ￦ 593,531 288,068 (874,667 ) 114,589 (56,438 ) (168,961 ) (2,844 ) 46,750 31,884 (*) For the year ended December 31, 2017, the net gain on valuation of derivatives applying cash flow hedge accounting of ￦20,868 million, net of tax, is included in other comprehensive income or loss.

Other Financial Assets

Other Financial Assets	12 Months Ended
	Dec. 31, 2017
Other Financial Assets [Abstract]
Other Financial Assets	12. Other Financial Assets (1) Other financial assets as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Loans and receivables ￦ 198,133 683,353 244,309 711,069 Allowance for doubtful accounts — (4,532 ) — (8,948 ) Present value discount (1,001 ) (41,746 ) (976 ) (39,813 ) Long / short-term financial instruments 2,281,460 414,466 1,702,084 542,430 Financial assets at fair value through profit or loss — — — 111,512 ￦ 2,478,592 1,051,541 1,945,417 1,316,250 (2) Loans and receivables as of December 31, 2016 and 2017 are as follows: 2016 Face value Allowance for Present value Book value In millions of won Short-term loans and receivables Loans for tuition ￦ 29,028 — (1,001 ) 28,027 Loans for housing 12,556 — — 12,556 Fisheries loan 352 — — 352 Other loans 156,197 — — 156,197 198,133 — (1,001 ) 197,132 Long-term loans and receivables Loans for tuition 404,200 — (41,593 ) 362,607 Loans for housing 125,850 — — 125,850 Loans for related parties 91,249 (4,532 ) — 86,717 Fisheries loan 1,312 — (153 ) 1,159 Other loans 60,742 — — 60,742 683,353 (4,532 ) (41,746 ) 637,075 ￦ 881,486 (4,532 ) (42,747 ) 834,207 2017 Face value Allowance for Present value discount Book value In millions of won Short-term loans and receivables Loans for tuition ￦ 33,763 — (976 ) 32,787 Loans for housing 14,126 — — 14,126 Fisheries loan 352 — — 352 Other loans 196,068 — — 196,068 244,309 — (976 ) 243,333 Long-term loans and receivables Loans for tuition 408,803 — (39,716 ) 369,087 Loans for housing 140,452 — — 140,452 Loans for related parties 94,581 (8,948 ) — 85,633 Fisheries loan 960 — (97 ) 863 Other loans 66,273 — — 66,273 711,069 (8,948 ) (39,813 ) 662,308 ￦ 955,378 (8,948 ) (40,789 ) 905,641 (3) Changes in the allowance for doubtful accounts of loans and receivables for the year ended December 31, 2017 is as follows: 2017 In millions of won Beginning balance ￦ 4,532 Bad debt expense 2,465 Other 1,951 Ending balance ￦ 8,948 (4) Long-term and short-term financial instruments as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Time deposits ￦ 1,820,391 30,000 1,479,034 2 ABCP 351,800 132,600 145,000 65,600 CP 16,000 — 58,050 — CD 60,443 — 10,000 — RP — 1,521 10,000 1,634 Others 32,826 250,345 — 475,194 ￦ 2,281,460 414,466 1,702,084 542,430

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
Inventories [Abstract]
Inventories	13. Inventories Inventories as of December 31, 2016 and 2017 are as follows: 2016 Acquisition cost Valuation allowance Book value In millions of won Raw materials ￦ 3,182,711 (1,323 ) 3,181,388 Merchandise 20 — 20 Work-in-progress 118,640 — 118,640 Finished goods 57,659 — 57,659 Supplies 1,289,160 (4,553 ) 1,284,607 Inventories in transit 827,437 — 827,437 Other inventories 9,692 — 9,692 ￦ 5,485,319 (5,876 ) 5,479,443 2017 Acquisition cost Valuation allowance Book value In millions of won Raw materials ￦ 3,528,835 (2,829 ) 3,526,006 Merchandise 107 — 107 Work-in-progress 138,709 (1,028 ) 137,681 Finished goods 72,923 (1,517 ) 71,406 Supplies 1,581,661 (3,940 ) 1,577,721 Inventories in transit 679,358 — 679,358 Other inventories 9,807 — 9,807 ￦ 6,011,400 (9,314 ) 6,002,086 The allowance for loss on inventory valuation due to decrease in the net realizable value of inventory added to cost of sales was ￦533 million for the year ended December 31, 2015. The reversals of the allowance for loss on inventory valuation due to increase in the net realizable value of inventory deducted from cost of sales were ￦2,473 million and ￦437 million for the years ended December 31, 2016 and 2017, respectively. The amounts of loss from inventory valuation included in other gains or losses for the years ended December 31, 2015, 2016 and 2017 were ￦1,318 million, ￦2,683 million and ￦3,875 million, respectively.

Finance Lease Receivables

Finance Lease Receivables	12 Months Ended
	Dec. 31, 2017
Finance Lease Receivables [Abstract]
Finance Lease Receivables	14. Finance Lease Receivables (1) Finance lease contracts The Company entered into a power purchase agreement (“PPA”) with Jordan Electric Power Company to provide a 373MW level Qatrana gas combined power plant over a 25 year lease term, and accounts for the PPA as a finance lease. Also, the Company has fly-ash (2) Finance lease receivables as of December 31, 2016 and 2017 are as follows and included in current and non-current 2016 2017 Minimum lease Present value of Minimum lease Present value In millions of won Less than 1 year ￦ 55,708 12,225 49,542 13,067 1 ~ 5 years 423,152 214,176 381,181 203,990 More than 5 years 1,690,492 746,473 1,398,449 645,564 ￦ 2,169,352 972,874 1,829,172 862,621 (3) There are no impaired finance lease receivables as of December 31, 2016 and 2017.

Non-Financial Assets

Non-Financial Assets	12 Months Ended
	Dec. 31, 2017
Non-Financial Assets [Abstract]
Non-Financial Assets	15. Non-Financial Non-financial 2016 2017 Current Non-current Current Non-current In millions of won Advance payment ￦ 93,279 71,238 109,743 43,872 Prepaid expenses 228,142 78,066 251,715 90,118 Others(*1) 310,439 32,485 392,534 112,828 ￦ 631,860 181,789 753,992 246,818 (*1) Details of others as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Tax refund receivables ￦ 30,959 2,188 89,762 1,940 Greenhouse gas emissions rights 145,105 — 135,211 — Other quick assets(*2) 134,375 30,297 167,561 110,888 ￦ 310,439 32,485 392,534 112,828 (*2) The Company has recognized ￦92,128 million of shares in Orano Expansion (formerly, AREVA NC Expansion) as non-current non-financial

Consolidated Subsidiaries

Consolidated Subsidiaries	12 Months Ended
	Dec. 31, 2017
Consolidated Subsidiaries [Abstract]
Consolidated Subsidiaries	16. Consolidated Subsidiaries (1) Consolidated subsidiaries as of December 31, 2016 and 2017 are as follows: Percentage of ownership (%) Subsidiaries Key operation activities Location 2016 2017 Korea Hydro & Nuclear Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea South-East Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea Midland Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea Western Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea Southern Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea East-West Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % KEPCO Engineering & Construction Company, Inc.(*1) Architectural engineering for utility plant and others KOREA 65.77 % 65.77 % KEPCO Plant Service & Engineering Co., Ltd. Utility plant maintenance and others KOREA 51.00 % 51.00 % KEPCO Nuclear Fuel Co., Ltd. Nuclear fuel KOREA 96.36 % 96.36 % KEPCO KDN Co., Ltd. Electric power information technology and others KOREA 100.00 % 100.00 % Garolim Tidal Power Plant Co., Power generation KOREA 49.00 % 49.00 % KEPCO International HongKong Ltd. Holding company HONG KONG 100.00 % 100.00 % KEPCO International Philippines Inc. Holding company PHILIPPINES 100.00 % 100.00 % KEPCO Gansu International Ltd. Holding company HONG KONG 100.00 % 100.00 % KEPCO Philippines Holdings Inc. Holding company PHILIPPINES 100.00 % 100.00 % KEPCO Philippines Corporation Operation of utility plant PHILIPPINES 100.00 % 100.00 % KEPCO Ilijan Corporation Construction and operation of utility plant PHILIPPINES 51.00 % 51.00 % KEPCO Lebanon SARL Operation of utility plant LEBANON 100.00 % 100.00 % KEPCO Neimenggu International Ltd. Holding company HONG KONG 100.00 % 100.00 % KEPCO Shanxi International Ltd. Holding company HONG KONG 100.00 % 100.00 % KOMIPO Global Pte Ltd. Holding company SINGAPORE 100.00 % 100.00 % KEPCO Canada Energy Ltd. Resources development CANADA 100.00 % 100.00 % KEPCO Netherlands B.V. Holding company NETHERLANDS 100.00 % 100.00 % KOREA Imouraren Uranium Investment Corp. Holding company FRANCE 100.00 % 100.00 % KEPCO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOSEP Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOMIPO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOWEPO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOSPO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KEPCO Middle East Holding Company Holding company BAHRAIN 100.00 % 100.00 % Qatrana Electric Power Company Construction and operation of utility plant JORDAN 80.00 % 80.00 % KHNP Canada Energy, Ltd. Holding company CANADA 100.00 % 100.00 % KEPCO Bylong Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % Korea Waterbury Uranium Limited Partnership Resources development CANADA 79.64 % 79.64 % Korea Electric Power Nigeria Ltd. Operation of utility plant NIGERIA 100.00 % 100.00 % KEPCO Holdings de Mexico Holding company MEXICO 100.00 % 100.00 % KST Electric Power Company Construction and operation of utility plant MEXICO 56.00 % 56.00 % KEPCO Energy Service Company Operation of utility plant MEXICO 100.00 % 100.00 % KEPCO Netherlands S3 B.V. Holding company NETHERLANDS 100.00 % 100.00 % PT. KOMIPO Pembangkitan Jawa Bali Operation of utility plant INDONESIA 51.00 % 51.00 % PT. Cirebon Power Service(*2) Operation of utility plant INDONESIA 27.50 % 27.50 % KOWEPO International Corporation Operation of utility plant PHILIPPINES 99.99 % 99.99 % KOSPO Jordan LLC Operation of utility plant JORDAN 100.00 % 100.00 % EWP Philippines Corporation Holding company PHILIPPINES 100.00 % 100.00 % EWP America Inc. Holding company USA 100.00 % 100.00 % EWP Renewable Corporation Holding company USA 100.00 % 100.00 % DG Fairhaven Power, LLC Power generation USA 100.00 % 100.00 % DG Whitefield, LLC Power generation USA 100.00 % 100.00 % Springfield Power, LLC Power generation USA 100.00 % 100.00 % KNF Canada Energy Limited Holding company CANADA 96.36 % 96.36 % PT KEPCO Resource Indonesia Holding company INDONESIA 100.00 % 100.00 % EWP Barbados 1 SRL Holding company BARBADOS 100.00 % 100.00 % California Power Holdings, LLC Power generation USA 100.00 % 100.00 % Gyeonggi Green Energy Co., Ltd. Power generation KOREA 62.01 % 62.01 % PT. Tanggamus Electric Power Power generation INDONESIA 52.50 % 52.50 % Gyeongju Wind Power Co., Ltd. Power generation KOREA 70.00 % 70.00 % KOMIPO America Inc. Holding company USA 100.00 % 100.00 % EWPRC Biomass Holdings, LLC Holding company USA 100.00% 100.00% KOSEP USA, INC. Power generation USA 100.00% 100.00% PT. EWP Indonesia Holding company INDONESIA 99.95% 99.96% KEPCO Netherlands J3 B.V. Holding company NETHERLANDS 100.00% 100.00% Korea Offshore Wind Power Co., Ltd. Power generation KOREA 100.00% 100.00% Global One Pioneer B.V. Holding company NETHERLANDS 100.00% 100.00% Global Energy Pioneer B.V. Holding company NETHERLANDS 100.00% 100.00% Mira Power Limited(*3) Power generation PAKISTAN 76.00% 76.00% KOSEP Material Co., Ltd.(*4) Recycling fly ashes KOREA 46.22% 86.22% Commerce and Industry Energy Power generation KOREA 59.03% 59.03% KEPCO Singapore Holdings Pte., Ltd. Holding company SINGAPORE 100.00% 100.00% KOWEPO India Private Limited Holding company INDIA 100.00% 100.00% KEPCO KPS Philippines Corp. Utility plant maintenance and others PHILIPPINES 51.00% 51.00% KOSPO Chile SpA Holding company CHILE 100.00% 100.00% PT. KOWEPO Sumsel Operation And Maintenance Services Utility plant maintenance and others INDONESIA 95.00% 95.00% HeeMang Sunlight Power Co., Ltd. Operation of utility plant KOREA 100.00% 100.00% Fujeij Wind Power Company Operation of utility plant JORDAN 100.00% 100.00% KOSPO Youngnam Power Co., Ltd. Operation of utility plant KOREA 50.00% 50.00% HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) Holding company KOREA 96.67% 96.67% Chitose Solar Power Plant LLC Power generation JAPAN 80.10% 80.10% KEPCO Energy Solution Co. Ltd. Energy service KOREA 100.00% 100.00% Solar School Plant Co., Ltd. Power generation KOREA 100.00% 100.00% KOSPO Power Services Limitada Utility plant maintenance and others CHILE 65.00% 65.00% Energy New Industry Specialized Investment Private Investment Trust Holding company KOREA 99.75% 99.75% KOEN Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOMIPO Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOWEPO Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOSPO Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% EWP Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOWEPO Lao International Utility plant maintenance and others LAOS 100.00% 100.00% KEPCO US Inc. Holding company USA — 100.00% KEPCO Alamosa LLC Holding company USA — 50.10% Cogentrix Solar Services, LLC Holding company USA — 50.10% Solar Investments I, LLC Holding company USA — 50.10% Cogentrix of Alamosa, LLC Power generation USA — 50.10% KEPCO-LG Holding company USA — 70.00% Mangilao Investment LLC Holding company USA — 70.00% KEPCO-LG Power generation USA — 70.00% Jeju Hanlim Offshore Wind Co., Ltd. Power generation KOREA — 70.22% PT. Siborpa Eco Power Construction and operation of utility plant INDONESIA — 64.71% BSK E-New Holding company KOREA — 81.47% e-New Holding company KOREA — 75.92% Songhyun e-New Holding company KOREA — 80.45% (*1) Considering treasury stocks, the effective percentage of ownership is 66.08%. (*2) These subsidiaries are included in the consolidated financial statements as the Company obtained the majority of the voting power through the shareholders’ agreement. (*3) As of reporting date, the annual reporting period of all subsidiaries is December 31, except for Mira Power Limited which is November 30. (*4) The effective percentage of ownership has increased to 86.22% since Long Lasting Value exercised the put option to sell its investment to KOSEP during the year ended December 31, 2017. (*5) The Company guarantees a certain return on investment related to Commerce and Industry Energy Co., Ltd. for the financial investors. The financial investors have a right to sell their shares to the Company which can be exercised 84 months after the date of investment. Accordingly, the purchase price including the return on investment is classified as a liability. (2) Subsidiaries newly included in or excluded from consolidation for the year ended December 31, 2017 are as follows: Subsidiaries included in consolidation during the year ended December 31, 2017. Subsidiary Reason KEPCO US Inc. Newly established KEPCO Alamosa LLC Newly established Cogentrix Solar Services, LLC Newly established Solar Investments I, LLC Newly established Cogentrix of Alamosa, LLC Newly established KEPCO-LG Newly established Mangilao Investment LLC Newly established KEPCO-LG Newly established Jeju Hanlim Offshore Wind Co., Ltd. Newly established PT. Siborpa Eco Power Newly established BSK E-New Newly established e-New Newly established Songhyun e-New Newly established There are no subsidiaries excluded from consolidation during the year ended December 31, 2017. (3) Summary of financial information of consolidated subsidiaries as of and for the years ended December 31, 2016 and 2017 are as follows: 2016 Subsidiaries Total assets Total liabilities Sales Profit (loss) for the period In millions of won Korea Hydro & Nuclear Power Co., Ltd. ￦ 52,782,915 27,366,938 11,168,579 2,454,810 Korea South-East Power Co., Ltd. 9,773,778 4,794,330 5,093,598 531,061 Korea Midland Power Co., Ltd. 9,066,666 5,416,336 3,719,981 400,696 Korea Western Power Co., Ltd. 9,810,714 5,866,916 4,169,712 401,936 Korea Southern Power Co., Ltd. 9,806,023 5,637,950 4,200,035 426,337 Korea East-West Power Co., Ltd. 8,967,951 4,488,911 4,210,898 467,603 KEPCO Engineering & Construction Company, Inc. 786,596 364,676 506,012 17,796 KEPCO Plant Service & Engineering Co., Ltd. 1,086,421 301,490 1,214,304 86,657 KEPCO Nuclear Fuel Co., Ltd. 713,230 346,012 309,911 33,115 KEPCO KDN Co., Ltd. 519,901 205,869 588,160 43,127 Garolim Tidal Power Plant Co., Ltd. 632 346 — -24 KEPCO International HongKong Ltd. 173,138 41 — 4,532 KEPCO International Philippines Inc. 114,141 1,468 — 56,783 KEPCO Gansu International Ltd. 17,928 557 — (18 ) KEPCO Philippines Holdings Inc. 125,100 27 — 13,517 KEPCO Philippines Corporation 13,704 8,949 — (8,717 ) KEPCO Ilijan Corporation 558,030 58,449 116,667 51,552 KEPCO Lebanon SARL 1,458 10,312 — 810 KEPCO Neimenggu International Ltd. 186,636 — — 7,082 KEPCO Shanxi International Ltd. 549,189 218,047 — 5,812 KOMIPO Global Pte Ltd. 223,082 1,095 — 36,764 KEPCO Canada Energy Ltd. 202 24 — (27,216 ) KEPCO Netherlands B.V. 128,014 35 — 224 KOREA Imouraren Uranium Investment Corp. 154,302 764 — (68,417 ) KEPCO Australia Pty., Ltd. 503,657 1,545 3,670 (19,006 ) KOSEP Australia Pty., Ltd. 25,174 521 5,357 4,028 KOMIPO Australia Pty., Ltd. 25,413 10 5,388 4,023 KOWEPO Australia Pty., Ltd. 25,550 10 5,357 4,012 KOSPO Australia Pty., Ltd. 25,625 10 5,357 4,033 KEPCO Middle East Holding Company 128,846 125,008 — 6,840 Qatrana Electric Power Company 546,123 417,800 18,866 19,601 KHNP Canada Energy, Ltd. 54,374 46 — (6,304 ) KEPCO Bylong Australia Pty., Ltd. 220,721 277,358 — (2,357 ) Korea Waterbury Uranium Limited Partnership 20,882 149 — 2,348 Korea Electric Power Nigeria Ltd. 696 493 9,794 35 KEPCO Holdings de Mexico 262 19 — 251 KST Electric Power Company 596,823 539,459 146,295 17,322 KEPCO Energy Service Company 1,309 310 5,337 580 KEPCO Netherlands S3 B.V. 55,609 54 — 3,731 PT. KOMIPO Pembangkitan Jawa Bali 16,246 4,549 21,632 8,989 PT. Cirebon Power Service 3,456 1,228 7,463 301 KOWEPO International Corporation — — — — KOSPO Jordan LLC 11,524 687 7,321 317 EWP Philippines Corporation 1,966 955 — (41 ) EWP America Inc.(*) 104,809 80,252 33,616 (8,704 ) KNF Canada Energy Limited 1,967 20 — (46 ) PT KEPCO Resource Indonesia 913 18 — (341 ) EWP Barbados 1 SRL 267,859 425 1,656 (902 ) Gyeonggi Green Energy Co., Ltd. 301,126 221,078 108,557 19,211 PT. Tanggamus Electric Power 184,861 167,641 40,903 2,041 Gyeongju Wind Power Co., Ltd. ￦ 76,569 49,293 6,413 1,269 KOMIPO America Inc. 11,518 2,432 — (2,240 ) KOSEP USA, INC. 159 39,028 3,791 (72,817 ) PT. EWP Indonesia 2,154 50 — 1,088 KEPCO Netherlands J3 B.V. 125,337 68 — 12,433 Korea Offshore Wind Power Co., Ltd. 37,826 2,048 — (4,960 ) Global One Pioneer B.V. 161 22 — (54 ) Global Energy Pioneer B.V. 338 22 — (59 ) Mira Power Limited 178,141 133,730 — (954 ) KOSEP Material Co., Ltd. 2,398 1,497 3,232 (901 ) Commerce and Industry Energy Co., Ltd. 99,432 87,316 28,375 (536 ) KEPCO Singapore Holdings Pte., Ltd. 2,568 13 — (33 ) KOWEPO India Private Limited 879 — — 1 KEPCO KPS Philippines Corp. 7,897 1,213 12,843 2,060 KOSPO Chile SpA 6,656 4,787 — 125 PT. KOWEPO Sumsel Operation and Maintenance Services 1,439 700 6,165 (96 ) HeeMang Sunlight Power Co., Ltd. 7,102 3,391 12 (308 ) Fujeij Wind Power Company 47,935 46,636 — (873 ) KOSPO Youngnam Power Co., Ltd. 284,368 205,680 — (931 ) HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) 3,002 — — 9 Chitose Solar Power Plant LLC 49,728 38,806 — (811 ) KEPCO Energy Solution Co. Ltd. 299,933 233 — (300 ) Solar School Plant Co., Ltd. 200,268 259 1 9 KOSPO Power Services Limitada 4,385 1,262 7,300 2,963 Energy New Industry Specialized Investment Private Investment Trust 501,275 33 — (7 ) KOEN Bylong Pty., Ltd. 6,135 — — — KOMIPO Bylong Pty., Ltd. 6,135 — — — KOWEPO Bylong Pty., Ltd. 6,135 — — — KOSPO Bylong Pty., Ltd. 6,135 — — — EWP Bylong Pty., Ltd. 6,135 — — — KOWEPO Lao International 218 181 — (108 ) (*) Financial information of EWP America Inc. includes that of six other subsidiaries, EWP Renewable Co., DG Fairhaven Power, LLC, DG Whitefield, LLC, Springfield Power, LLC, California Power Holdings, LLC, and EWPRC Biomass Holdings, LLC. 2017 Subsidiaries Total assets Total liabilities Sales Profit (loss) for the period In millions of won Korea Hydro & Nuclear Power Co., Ltd. ￦ 55,011,096 29,252,816 9,415,751 854,346 Korea South-East Power Co., Ltd. 9,879,577 4,844,184 5,387,846 130,371 Korea Midland Power Co., Ltd. 9,893,822 6,148,173 4,167,009 104,591 Korea Western Power Co., Ltd. 9,660,426 5,739,534 4,199,079 110,939 Korea Southern Power Co., Ltd. 9,648,741 5,401,216 4,397,552 98,817 Korea East-West Power Co., Ltd. 8,855,518 4,204,187 4,644,330 217,599 KEPCO Engineering & Construction Company, Inc. 762,166 305,134 490,193 21,222 KEPCO Plant Service & Engineering Co., Ltd. 1,195,086 294,689 1,232,113 135,482 KEPCO Nuclear Fuel Co., Ltd. 792,187 421,088 279,664 4,557 KEPCO KDN Co., Ltd. 524,520 155,715 619,470 48,968 Garolim Tidal Power Plant Co., Ltd. 619 345 — (12 ) KEPCO International HongKong Ltd. 153,529 1 — 4,380 KEPCO International Philippines Inc. 102,323 886 — 47,201 KEPCO Gansu International Ltd. 11,567 493 — (29 ) KEPCO Philippines Holdings Inc. 127,922 2,621 — 43,218 KEPCO Philippines Corporation 6,293 114 — 2,098 KEPCO Ilijan Corporation 474,624 57,801 109,183 66,320 KEPCO Lebanon SARL 1,069 9,281 — (219 ) KEPCO Neimenggu International Ltd. 165,937 — — 500 KEPCO Shanxi International Ltd. 497,990 193,309 — 3,796 KOMIPO Global Pte Ltd. 225,411 1,497 — 21,858 KEPCO Canada Energy Ltd. 132 22 — (32 ) KEPCO Netherlands B.V. 114,911 49 — 17,309 KOREA Imouraren Uranium Investment Corp. 151,278 131 — 1,490 KEPCO Australia Pty., Ltd. 466,654 569 — (568 ) KOSEP Australia Pty., Ltd. 27,076 333 12,096 1,601 KOMIPO Australia Pty., Ltd. 31,441 4,691 12,096 1,133 KOWEPO Australia Pty., Ltd. 31,586 4,691 12,096 1,232 KOSPO Australia Pty., Ltd. 29,472 4,221 12,096 (2,759 ) KEPCO Middle East Holding Company 95,812 90,842 — 2,913 Qatrana Electric Power Company 460,206 327,401 18,892 23,310 KHNP Canada Energy, Ltd. 51,994 31 — (92 ) KEPCO Bylong Australia Pty., Ltd. 242,364 277,549 — 20,271 Korea Waterbury Uranium Limited Partnership 20,886 136 — (59 ) Korea Electric Power Nigeria Ltd. 238 76 2,164 29 KEPCO Holdings de Mexico 235 30 — (20 ) KST Electric Power Company 546,242 478,230 120,126 16,154 KEPCO Energy Service Company 1,793 451 6,773 976 KEPCO Netherlands S3 B.V. 46,642 53 — 2,382 PT. KOMIPO Pembangkitan Jawa Bali 11,261 4,769 20,956 4,666 PT. Cirebon Power Service 2,808 155 7,439 592 KOWEPO International Corporation — 8 — (2 ) KOSPO Jordan LLC 24,077 13,594 7,331 953 EWP Philippines Corporation 1,708 836 — (17 ) EWP America Inc.(*1) 79,854 67,308 23,543 (9,737 ) KNF Canada Energy Limited 1,884 31 — (43 ) PT KEPCO Resource Indonesia 491 — — (311 ) EWP Barbados 1 SRL 235,096 450 — (2,585 ) Gyeonggi Green Energy Co., Ltd. 282,408 199,160 95,192 3,203 PT. Tanggamus Electric Power 179,317 160,144 34,281 4,640 Gyeongju Wind Power Co., Ltd. 112,279 82,124 7,219 2,400 KOMIPO America Inc. 10,505 521 — 2,071 KOSEP USA, INC. 184 9,065 — 26,997 2017 Subsidiaries Total assets Total liabilities Sales Profit (loss) for the period In millions of won PT. EWP Indonesia ￦ 2,035 23 — 1,916 KEPCO Netherlands J3 B.V. 122,612 76 — 12,115 Korea Offshore Wind Power Co., Ltd. 190,195 1,985 — (6,997 ) Global One Pioneer B.V. 151 38 — (80 ) Global Energy Pioneer B.V. 309 41 — (87 ) Mira Power Limited 208,150 163,198 — 737 KOSEP Material Co., Ltd. 2,751 1,448 3,128 320 Commerce and Industry Energy Co., Ltd. 99,129 87,926 30,577 (749 ) KEPCO Singapore Holdings Pte., Ltd. 3,265 4 — (24 ) KOWEPO India Private Limited 781 — — (46 ) KEPCO KPS Philippines Corp. 6,636 235 6,840 555 KOSPO Chile SpA 133,570 50,109 — 1,066 PT. KOWEPO Sumsel Operation And Maintenance Services 1,350 279 7,651 659 HeeMang Sunlight Power Co., Ltd. 6,876 3,395 105 (229 ) Fujeij Wind Power Company 165,636 156,099 — 8,836 KOSPO Youngnam Power Co.,Ltd. 412,785 333,302 68,973 939 HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) 3,002 — — 12 Chitose Solar Power Plant LLC 136,098 121,622 7,083 4,100 KEPCO Energy Solution Co. Ltd. 313,401 12,376 5,544 1,325 Solar School Plant Co., Ltd. 201,482 599 67 874 KOSPO Power Services Limitada 3,901 887 11,067 666 Energy New Industry Specialized Investment Private Investment Trust(*3) 506,207 2,118 — 52 KOEN Bylong Pty., Ltd. 5,875 — — — KOMIPO Bylong Pty., Ltd. 5,875 — — — KOWEPO Bylong Pty., Ltd. 5,875 — — — KOSPO Bylong Pty., Ltd. 5,875 — — — EWP Bylong Pty., Ltd. 5,875 — — — KOWEPO Lao International 3,259 1,452 3,624 1,881 KEPCO US Inc. 16,913 — — — KEPCO Alamosa LLC 33,144 492 — (218 ) Cogentrix Solar Services, LLC(*2) 84,458 53,116 8,958 (112 ) KEPCO-LG 24,131 24,395 — (278 ) Mangilao Investment LLC 24,131 — — — KEPCO-LG 24,002 134 — (278 ) Jeju Hanlim Offshore Wind Co., Ltd. 36 — — — PT. Siborpa Eco Power 11,562 214 — (518 ) (*1) Financial information of EWP America Inc. includes that of six other subsidiaries, EWP Renewable Corporation, DG Fairhaven Power, LLC, DG Whitefield, LLC, Springfield Power, LLC, California Power Holdings, LLC, and EWPRC Biomass Holdings, LLC. (*2) Financial information of Cogentrix Solar Services, LLC includes that of two other subsidiaries, Solar Investments I, LLC and Cogentrix of Alamosa, LLC. (*3) Financial information of Energy New Industry Specialized Investment Private Investment Trust includes that of three other subsidiaries, BSK E-New e-New e-New (4) Significant restrictions on abilities to subsidiaries are as follows: Company Nature and extent of any significant restrictions Gyeonggi Green Energy Co., Ltd. Acquisition or disposal of assets of more than ￦35 billion, change in the capacity of cogeneration units (except for the change due to performance improvement of equipment, maintenance) will require unanimous consent of all directors. KOSPO Youngnam Power Co., Ltd. Dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Shares cannot be wholly or partially transferred without prior written consent of financial institutions. (5) Details of non-controlling 2016 Description KEPCO KEPCO Plant KEPCO Construction Others Total In millions of won Percentage of ownership 49.00 % 49.00 % 33.92 % Current assets ￦ 154,758 553,924 270,553 1,211,510 2,190,745 Non-current 403,272 532,497 516,043 2,379,882 3,831,694 Current liabilities (19,256 ) (264,506 ) (286,444 ) (297,510 ) (867,716 ) Non-current (39,193 ) (36,984 ) (78,232 ) (1,919,924 ) (2,074,333 ) Net assets 499,581 784,931 421,920 1,373,958 3,080,390 Book value of non-controlling 244,794 384,616 143,115 684,093 1,456,618 Sales 116,667 1,214,304 506,012 674,461 2,511,444 Profit for the period 51,552 86,657 17,796 102,170 258,175 Profit for the period attributable to non-controlling 25,260 42,462 6,036 26,709 100,467 Cash flows from operating activities 102,546 121,240 18,748 84,086 326,620 Cash flows from investing activities (117 ) 79,807 (7,556 ) (367,674 ) (295,540 ) Cash flows from financing activities before dividends to non-controlling (56,863 ) (39,911 ) (1,634 ) 877,863 779,455 Dividends to non-controlling (55,705 ) (36,139 ) (2,539 ) (22,054 ) (116,437 ) Effect of exchange rate fluctuation 1,529 127 (854 ) 7,216 8,018 Net increase (decrease) of cash and cash equivalents (8,610 ) 125,124 6,165 579,437 702,116 2017 Description KEPCO Ilijan KEPCO Plant KEPCO Construction Others Total In millions of won Percentage of ownership 49.00 % 49.00 % 33.92 % Current assets ￦ 160,588 623,934 257,529 1,269,175 2,311,226 Non-current 314,036 571,152 504,637 2,588,833 3,978,658 Current liabilities (21,546 ) (278,562 ) (221,860 ) (394,320 ) (916,288 ) Non-current (36,255 ) (16,127 ) (83,274 ) (2,014,925 ) (2,150,581 ) Net assets 416,823 900,397 457,032 1,448,763 3,223,015 Book value of non-controlling 204,243 441,194 155,025 612,245 1,412,707 Sales 109,183 1,232,113 490,193 719,087 2,550,576 Profit for the period 66,320 135,482 21,222 66,419 289,443 Profit for the period attributable to non-controlling 32,497 66,386 7,199 20,447 126,529 Cash flows from operating activities 123,534 129,801 62,578 60,021 375,934 Cash flows from investing activities (5,276 ) (193,408 ) (8,622 ) (409,353 ) (616,659 ) Cash flows from financing activities before dividends to non-controlling (44,442 ) (15,606 ) (55,504 ) 339,432 223,880 Dividends to non-controlling (48,855 ) (14,994 ) (1,419 ) (20,840 ) (86,108 ) Effect of exchange rate fluctuation (7,432 ) (1,267 ) (101 ) (24,206 ) (33,006 ) Net increase (decrease) of cash and cash equivalents 17,529 (95,474 ) (3,068 ) (54,946 ) (135,959 ) (6) Changes in goodwill (i) Details of goodwill as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Acquisition cost ￦ 2,582 2,582 Accumulated impairment — — Carrying book value ￦ 2,582 2,582 (ii) There are no changes in goodwill for the years ended December 31, 2016 and 2017. (7) Disposals of subsidiaries KEPCO Canada Uranium Investment Limited Partnership was dissolved and the Company liquidated DG Kings Plaza, LLC during the year ended December 31, 2016. (i) The fair value of proceeds from disposal as of December 31, 2016 is as follows: 2016 In millions of won Cash received upon dissolution ￦ 898 Net assets transferred due to dissolution 34,148 ￦ 35,046 (ii) The carrying value of assets and liabilities of subsidiaries as at the date the Company lost its control during the year ended December 31, 2016 are as follows: 2016 In millions of won Current assets Cash and cash equivalents ￦ 898 Current financial assets, net 81 Non-current Available-for-sale 34,089 Current liabilities Current financial liabilities (22 ) ￦ 35,046 (iii) Gain from disposals of subsidiaries for the year ended December 31, 2016 is as follows: 2016 In millions of won Fair value of sale price ￦ 35,046 Net assets disposed (35,046 ) Non-controlling — Realization of unrealized gain — Other comprehensive income — Gain from disposals of subsidiaries ￦ — (iv) Net cash flow from sales of subsidiaries for the year ended December 31, 2016 is as follows: 2016 In millions of won Consideration received in cash ￦ 898 Less: cash held by disposed subsidiaries (898 ) Net cash flow ￦ — (8) Cash dividends received from subsidiaries for the years ended December 31, 2015, 2016 and 2017, respectively, are as follows: Subsidiaries 2015 2016 2017 In millions of won Korea Hydro & Nuclear Power Co., Ltd. ￦ 446,399 635,200 543,072 Korea South-East Power Co., Ltd. 57,485 124,169 106,546 Korea Midland Power Co., Ltd. 16,580 23,073 54,305 Korea Western Power Co., Ltd. 22,749 36,238 66,992 Korea Southern Power Co., Ltd. 10,272 17,849 60,630 Korea East-West Power Co., Ltd. 25,280 67,906 94,430 KEPCO Engineering & Construction Company, Inc. 14,574 5,069 2,765 KEPCO Plant Service & Engineering Co., Ltd. 40,584 39,911 15,607 KEPCO Nuclear Fuel Co., Ltd. 6,280 3,411 3,231 KEPCO KDN Co., Ltd. 4,046 3,392 4,352 KEPCO International HongKong Ltd. 25,826 9,107 4,304 KEPCO International Philippines Inc. 32,891 61,862 44,906 KEPCO Ilijan Corporation 38,128 57,979 50,849 KEPCO Philippines Holdings Inc. 19,221 17,747 26,023 KEPCO Neimenggu International Ltd. 25,338 10,735 — KOMIPO Global Pte Ltd. — 10,432 — Qatrana Electric Power Company 16,857 8,331 5,939 KOSPO Jordan LLC — 1,095 — KEPCO Energy Service Company — 294 — EWP Philippines Corporation 5,586 — — KEPCO Netherlands S3 B.V. 1,382 — — PT. KOMIPO Pembangkitan Jawa Bali 3,169 3,222 3,188 KEPCO Netherlands J3 B.V. 19,254 12,507 — Gyeongju Wind Power Co., Ltd. 1,294 679 — Energy New Industry Specialized Investment Private Investment Trust — — 291 HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) — — 11 KOSPO Power Services Limitada — — 425 Cogentrix Solar Services, LLC — — 344 ￦ 833,195 1,150,208 1,088,210

Investments in Associates and J

Investments in Associates and Joint Ventures	12 Months Ended
	Dec. 31, 2017
Investments in Associates and Joint Ventures [Abstract]
Investments in Associates and Joint Ventures	17. Investments in Associates and Joint Ventures (1) Investments in associates and joint ventures as of December 31, 2016 and 2017 are as follows: 2016 Investees Key operation activities Location Percentage of Acquisition cost Book value In millions of won <Associates> Korea Gas Corporation(*1) Importing and wholesaling LNG KOREA 20.47 % ￦ 94,500 1,933,877 Korea Electric Power Industrial Development Co., Ltd. Electricity metering and others KOREA 29.00 % 4,727 20,475 YTN Co., Ltd. Broadcasting KOREA 21.43 % 59,000 38,156 Cheongna Energy Co., Ltd. Generating and distributing vapor and hot/cold water KOREA 43.90 % 48,353 12,373 Gangwon Wind Power Co., Ltd.(*2) Power generation KOREA 15.00 % 5,725 13,069 Hyundai Green Power Co., Ltd. Power generation KOREA 29.00 % 88,885 115,998 Korea Power Exchange(*6) Management of power market and others KOREA 100.00 % 127,839 223,238 AMEC Partners Korea Ltd.(*3) Resources development KOREA 19.00 % 707 225 Hyundai Energy Co., Ltd.(*9) Power generation KOREA 30.66 % 71,070 1,031 Ecollite Co., Ltd. Artificial light-weight aggregate KOREA 36.10 % 1,516 — Taebaek Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,810 4,750 Taeback Guinemi Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,420 3,131 Pyeongchang Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,875 3,383 Daeryun Power Co., Ltd.(*3, 10) Power generation KOREA 13.13 % 25,477 29,873 Changjuk Wind Power Co., Ltd. Power generation KOREA 30.00 % 3,801 6,930 KNH Solar Co., Ltd. Power generation KOREA 27.00 % 1,296 2,073 SPC Power Corporation Power generation PHILIPPINES 38.00 % 20,635 56,818 Gemeng International Energy Co., Ltd. Power generation CHINA 34.00 % 413,153 680,065 PT. Cirebon Electric Power Power generation INDONESIA 27.50 % 40,365 96,658 KNOC Nigerian East Oil Co., Resources development NIGERIA 14.63 % 12 — KNOC Nigerian West Oil Co., Resources development NIGERIA 14.63 % 12 — PT Wampu Electric Power Power generation INDONESIA 46.00 % 21,292 23,188 PT. Bayan Resources TBK Resources development INDONESIA 20.00 % 615,860 402,667 S-Power Power generation KOREA 49.00 % 132,300 123,912 Pioneer Gas Power Limited(*8) Power generation INDIA 40.00 % 49,831 50,740 Eurasia Energy Holdings Power generation and resources development RUSSIA 40.00 % 461 — Xe-Pian Xe-Namnoy Power generation LAOS 25.00 % 49,119 51,544 Hadong Mineral Fiber Co., Ltd.(*17) Recycling fly ashes KOREA 8.33 % 50 — Green Biomass Co., Ltd.(*12) Power generation KOREA 14.00 % 714 47 PT. Mutiara Jawa Manufacturing and operating floating coal terminal INDONESIA 29.00 % 2,978 — Samcheok Eco Materials Co., Recycling fly ashes KOREA 2.35 % 686 — Noeul Green Energy Co., Ltd. Power generation KOREA 29.00 % 1,740 1,217 Naepo Green Energy Co., Ltd. Power generation KOREA 25.00 % 29,200 25,438 Goseong Green Energy Co., Ltd.(*2) Power generation KOREA 1.12 % 2,900 2,663 Gangneung Eco Power Co., Ltd.(*2) Power generation KOREA 1.61 % 2,900 2,646 Shin Pyeongtaek Power Co., Ltd. Power generation KOREA 40.00 % 40 — Heang Bok Do Si Photovoltaic Power Co., Ltd. Power generation KOREA 28.00 % 194 181 DS POWER Co., Ltd.(*2) Power generation KOREA 14.44 % 17,900 7,190 Dongducheon Dream Power Co., Ltd. Power generation KOREA 33.61 % 61,535 46,876 KS Solar Co., Ltd.(*3) Power generation KOREA 19.00 % 637 604 Yeongwol Energy Station Co., Power generation KOREA 10.00 % 1,400 — Jinbhuvish Power Generation Pvt. Power generation INDIA 5.16 % ￦ 9,000 — SE Green Energy Co., Ltd. Power generation support KOREA 47.76 % 3,821 3,525 Daegu Photovoltaic Co., Ltd. Power generation KOREA 29.00 % 1,230 1,700 Jeongam Wind Power Co., Ltd. Power generation KOREA 40.00 % 5,580 4,000 Korea Power Engineering Service Co., Ltd. Construction and service KOREA 29.00 % 290 2,810 Busan Green Energy Co., Ltd. Power generation KOREA 29.00 % 14,564 13,803 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.)(*2) Power generation KOREA 18.87 % 1,000 — Korea Electric Vehicle Charging Service Electric vehicle charge service KOREA 28.00 % 1,596 1,103 Ulleungdo Natural Energy Co., Ltd. Renewable power generation KOREA 29.85 % 8,000 6,894 Korea Nuclear Partners Co., Ltd. Electric material agency KOREA 29.00 % 290 248 Tamra Offshore Wind Power Co., Ltd. Power generation KOREA 27.00 % 8,910 7,015 Korea Electric Power Corporation Developing electric enterprises KOREA 98.09 % 51,500 50,856 Energy Infra Asset Management Co., Ltd.(*3) Asset management KOREA 9.90 % 297 259 Daegu clean Energy Co., Ltd. Renewable power generation KOREA 28.00 % 140 140 YaksuESS Co., Ltd Installing ESS related equipment KOREA 29.00 % 210 196 Nepal Water & Energy Development Company Private Limited(*14) Construction and operation of utility plant NEPAL 52.77 % 18,568 18,667 2,134,911 4,092,252 <Joint ventures> KEPCO-Uhde Inc.(*7) Power generation KOREA 52.8 % 11,355 301 Eco Biomass Energy Sdn. Bhd.(*7) Power generation MALAYSIA 61.53 % 9,661 — Datang Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 27,660 28,239 Shuweihat Asia Power Investment B.V. Holding company NETHERLANDS 49.00 % 46,037 — Shuweihat Asia Operation & Maintenance Company(*7) Maintenance of utility plant CAYMAN 55.00 % 30 450 Waterbury Lake Uranium L.P. Resources development CANADA 36.97 % 26,602 21,314 ASM-BG Power generation BULGARIA 50.00 % 16,101 21,488 RES Technology AD Power generation BULGARIA 50.00 % 15,595 13,582 KV Holdings, Inc. Power generation PHILIPPINES 40.00 % 2,103 2,098 KEPCO SPC Power Corporation(*7) Construction and operation of utility plant PHILIPPINES 75.20 % 94,579 245,367 Canada Korea Uranium Limited Partnership(*5) Resources development CANADA 12.50 % 5,404 — Gansu Datang Yumen Wind Power Co., Ltd. Power generation CHINA 40.00 % 16,621 12,821 Datang Chifeng Renewable Power Co., Ltd. Power generation CHINA 40.00 % 121,928 166,535 Datang KEPCO Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 10,858 10,843 Rabigh Electricity Company Power generation SAUDI ARABIA 40.00 % 109,743 97,802 Rabigh Operation & Maintenance Company Limited Maintenance of utility plant SAUDI ARABIA 40.00 % 70 4,427 Jamaica Public Service Company Limited Power generation JAMAICA 40.00 % 301,910 249,453 KW Nuclear Components Co., Ltd. Manufacturing KOREA 45.00 % 833 7,133 Busan Shinho Solar Power Co., Ltd. Power generation KOREA 25.00 % 2,100 3,814 GS Donghae Electric Power Co., Ltd. Power generation KOREA 34.00 % 204,000 205,948 Global Trade Of Power System Co., Ltd. Exporting products and technology of small or medium business by proxy KOREA 29.00 % ￦ 290 477 Expressway Solar-light Power Generation Co., Ltd. Power generation KOREA 29.00 % 1,856 2,343 KODE NOVUS I LLC Power generation USA 50.00 % 19,213 — KODE NOVUS II LLC Power generation USA 50.00 % 12,756 — Daejung Offshore Wind Power Co., Ltd. Power generation KOREA 49.90 % 4,990 3,015 Amman Asia Electric Power Power generation JORDAN 60.00 % 111,476 153,857 KAPES, Inc.(*7) R&D KOREA 51.00 % 5,629 4,758 Dangjin Eco Power Co., Ltd. Power generation KOREA 34.00 % 56,100 53,253 Honam Wind Power Co., Ltd. Power generation KOREA 29.00 % 3,480 4,451 Chun-cheon Energy Co., Ltd. Power generation KOREA 29.90 % 52,700 50,592 Yeonggwangbaeksu Wind Power Co., Ltd.(*3) Power generation KOREA 15.00 % 3,000 2,689 Nghi Son 2 Power Ltd. Power generation VIETNAM 50.00 % 1,788 229 Kelar S.A(*7) Power generation CHILE 65.00 % 4,180 — PT. Tanjung Power Indonesia Power generation INDONESIA 35.00 % 746 1,946 Incheon New Power Co., Ltd. Power generation KOREA 29.00 % 461 563 Seokmun Energy Co., Ltd. Power generation KOREA 29.00 % 580 391 Daehan Wind Power PSC Power generation JORDAN 50.00 % 285 16 Barakah One Company(*16) Power generation UAE 18.00 % 118 116 Nawah Energy Company(*16) Operation of utility plant UAE 18.00 % 296 290 MOMENTUM International thermonuclear experimental reactor construction management FRANCE 33.33 % 1 67 Daegu Green Power Co., Ltd.(*15) Power generation KOREA 29.00 % 46,225 47,528 1,349,360 1,418,196 ￦ 3,484,271 5,510,448 (*1) The effective percentage of ownership is 21.57% considering treasury stocks. (*2) The Company can exercise significant influence by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors. (*3) The Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity. (*4) The Company can exercise significant influence by virtue of its contractual right to appoint one out of four members of the steering committee of the entity. Moreover, the Company has significant financial transactions, which can affect its influence on the entity. (*5) The Company has joint control over the entity by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors. (*6) The Government regulates the Company’s ability to make operating and financial decisions over the entity, as the Government requires maintaining arms-length transactions between KPX and the Company’s other subsidiaries. The Company can exercise significant influence by its right to nominate directors to the board of directors of the entity. (*7) According to the shareholders’ agreement, all critical financial and operating decisions must be agreed to by all ownership parties. For these reasons, the entities are classified as joint ventures. (*8) As of reporting date, the annual reporting period of all associates and joint ventures ends on December 31, except for Pioneer Gas Power Limited whose reporting period ends on March 31. (*9) As of December 31, 2016, 15.64% of ownership of Hyundai Energy Co., Ltd. is held by NH Power ll Co., Ltd. and NH Bank. According to the shareholders’ agreement reached on March 2011, not only does the Company have a call option to acquire the investment in Hyundai Energy Co., Ltd. from NH Power ll Co., Ltd. and NH Bank with a certain rate of return, NH Power ll Co., Ltd. and NH Bank also have put options to dispose of their investment to the Company. In connection with this agreement, the Company applied the equity method on the investment in Hyundai Energy Co., Ltd. with 46.30% of ownership. (*10) The Company’s percentage of ownership has decreased due to the acquisition of Daeryun Power Co., Ltd. and the effective percentage of ownership is 19.45% considering stock purchase options. (*11) The Company’s effective percentage of ownership excluding the redeemable convertible preferred stock is 25.54%. (*12) The effective percentage of ownership is less than 20% but the Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity and the fact that the dominant portion of the investee’s sales transactions is generated from the Company. (*13) The effective percentage of ownership is more than 50% but the Company does not hold control over relevant business while it exercises significant influence by participating in the Investment Decision Committee. For this reason, the entity is classified as an associate. (*14) The effective percentage of ownership is more than 50%, but the Company does not control the entity according to the shareholders’ agreement. For this reason, the entity is classified as an associate. (*15) The entity is reclassified from associates to joint ventures since the terms of the shareholders’ agreement had been amended. (*16) The effective percentage of ownership is less than 20%, but the Company has joint control over the entity as decisions on the major activities require the unanimous consent of the parties that collectively control the entity. (*17) Although the percentage of ownership temporarily decreased to 8.33% from the difference in timing of capital payment by shareholders, the Company can exercise significant influence by virtue of its right to appoint a director to the board of directors of the entity based on the shareholders’ agreement. The percentage of ownership is 25.00% at the time of completion of capital payment. 2017 Investees Key operation activities Location Percentage of Acquisition Book In millions of won <Associates> Korea Gas Corporation(*1) Importing and wholesaling LNG KOREA 20.47 % ￦ 94,500 1,618,868 Korea Electric Power Industrial Development Co., Ltd. Electricity metering and others KOREA 29.00 % 4,727 21,838 YTN Co., Ltd. Broadcasting KOREA 21.43 % 59,000 40,606 Cheongna Energy Co., Ltd. Generating and distributing vapor and hot/cold water KOREA 43.90 % 48,353 8,337 Gangwon Wind Power Co., Ltd.(*2) Power generation KOREA 15.00 % 5,725 13,855 Hyundai Green Power Co., Ltd. Power generation KOREA 29.00 % 88,885 114,806 Korea Power Exchange(*5) Management of power market and others KOREA 100.00 % 127,839 237,631 AMEC Partners Korea Ltd.(*3) Resources development KOREA 19.00 % 707 215 Hyundai Energy Co., Ltd.(*8) Power generation KOREA 30.66 % 71,070 — Ecollite Co., Ltd. Artificial light-weight aggregate KOREA 36.10 % 1,516 — Taebaek Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,810 5,319 Taeback Guinemi Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,420 3,089 Pyeongchang Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,875 4,136 Daeryun Power Co., Ltd.(*3, 9) Power generation KOREA 13.13 % 25,477 25,113 Changjuk Wind Power Co., Ltd. Power generation KOREA 30.00 % 3,801 7,515 KNH Solar Co., Ltd. Power generation KOREA 27.00 % 1,296 2,218 SPC Power Corporation Power generation PHILIPPINES 38.00 % 20,635 52,283 Gemeng International Energy Co., Ltd. Power generation CHINA 34.00 % 413,153 649,973 PT. Cirebon Electric Power Power generation INDONESIA 27.50 % 40,365 97,410 KNOC Nigerian East Oil Co., Ltd.(*4) Resources development NIGERIA 14.63 % 12 — KNOC Nigerian West Oil Co., Ltd.(*4) Resources development NIGERIA 14.63 % 12 — PT Wampu Electric Power Power generation INDONESIA 46.00 % 21,292 29,403 PT. Bayan Resources TBK Resources development INDONESIA 20.00 % 615,860 451,831 S-Power Power generation KOREA 49.00 % 132,300 116,945 Pioneer Gas Power Limited(*7) Power generation INDIA 38.50 % 49,831 38,659 Eurasia Energy Holdings Power generation and resources development RUSSIA 40.00 % 461 — Xe-Pian Xe-Namnoy Power generation LAOS 25.00 % 71,481 61,779 Hadong Mineral Fiber Co., Ltd.(*3) Recycling fly ashes KOREA 8.33 % 50 — Green Biomass Co., Ltd.(*11, 14) Power generation KOREA 8.80 % 714 208 PT. Mutiara Jawa Manufacturing and operating floating coal terminal INDONESIA 29.00 % 2,978 — Samcheok Eco Materials Co., Ltd.(*10) Recycling fly ashes KOREA 2.35 % 686 — Noeul Green Energy Co., Ltd. Power generation KOREA 29.00 % 1,740 2,067 Naepo Green Energy Co., Ltd. Power generation KOREA 41.67 % ￦ 29,200 20,598 Goseong Green Energy Co., Ltd.(*2) Power generation KOREA 1.12 % 2,900 2,597 Gangneung Eco Power Co., Ltd.(*2) Power generation KOREA 1.61 % 2,900 2,583 Shin Pyeongtaek Power Co., Ltd. Power generation KOREA 40.00 % 43,920 34,903 Heang Bok Do Si Photovoltaic Power Co., Ltd. Power generation KOREA 28.00 % 194 187 Dongducheon Dream Power Co., Ltd. Power generation KOREA 33.61 % 111,134 53,233 Jinbhuvish Power Generation Pvt. Power generation INDIA 5.16 % 9,000 — SE Green Energy Co., Ltd. Power generation KOREA 47.76 % 3,821 3,476 Daegu Photovoltaic Co., Ltd. Power generation KOREA 29.00 % 1,230 1,718 Jeongam Wind Power Co., Ltd. Power generation KOREA 40.00 % 5,580 3,763 Korea Power Engineering Service Co., Ltd. Construction and service KOREA 29.00 % 290 3,659 Busan Green Energy Co., Ltd. Power generation KOREA 29.00 % 5,243 7,363 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.)(*2) Power generation KOREA 18.87 % 1,000 — Korea Electric Vehicle Charging Service Electric vehicle charge service KOREA 28.00 % 2,604 1,749 Ulleungdo Natural Energy Co., Ltd. Renewable power generation KOREA 29.85 % 8,000 6,370 Korea Nuclear Partners Co., Ltd. Electric material agency KOREA 29.00 % 290 383 Tamra Offshore Wind Power Co., Ltd. Power generation KOREA 27.00 % 8,910 8,560 Korea Electric Power Corporation Fund(*12) Developing electric enterprises KOREA 98.09 % 51,500 47,974 Energy Infra Asset Management Co., Ltd.(*3) Asset management KOREA 9.90 % 297 476 Daegu clean Energy Co., Ltd. Renewable power generation KOREA 28.00 % 140 11 YaksuESS Co., Ltd Installing ESS related equipment KOREA 29.00 % 210 194 Nepal Water & Energy Development Company Private Limited(*15) Construction and operation of utility plant NEPAL 62.13 % 33,577 30,498 Gwangyang Green Energy Co., Ltd. Power generation KOREA 20.00 % 2,000 1,772 PND solar., Ltd Power generation KOREA 29.00 % 1,250 1,250 2,240,761 3,837,421 <Joint ventures> KEPCO-Uhde Inc.(*6) Power generation KOREA 52.80 % 11,355 258 Eco Biomass Energy Sdn. Bhd.(*6) Power generation MALAYSIA 61.53 % 14,439 — Datang Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 27,660 27,262 Shuweihat Asia Power Investment B.V. Holding company NETHERLANDS 49.00 % 46,037 15,675 Shuweihat Asia Operation & Maintenance Company(*6) Maintenance of utility plant CAYMAN 55.00 % 30 663 Waterbury Lake Uranium L.P. Resources development CANADA 35.76 % 26,602 19,781 ASM-BG Power generation BULGARIA 50.00 % 16,101 21,202 RES Technology AD Power generation BULGARIA 50.00 % 15,595 14,375 KV Holdings, Inc. Power generation PHILIPPINES 40.00 % 2,103 1,918 KEPCO SPC Power Corporation(*6) Construction and operation of utility plant PHILIPPINES 75.20 % 94,579 217,094 Gansu Datang Yumen Wind Power Co., Ltd. Power generation CHINA 40.00 % 16,621 10,840 Datang Chifeng Renewable Power Co., Ltd. Power generation CHINA 40.00 % 121,928 171,055 Datang KEPCO Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 10,858 11,060 Rabigh Electricity Company Power generation SAUDI ARABIA 40.00 % 109,743 99,356 Rabigh Operation & Maintenance Company Limited Maintenance of utility plant SAUDI ARABIA 40.00 % 70 3,987 Jamaica Public Service Company Limited Power generation JAMAICA 40.00 % ￦ 301,910 221,153 KW Nuclear Components Co., Ltd. Manufacturing KOREA 45.00 % 833 6,703 Busan Shinho Solar Power Co., Ltd. Power generation KOREA 25.00 % 2,100 4,346 GS Donghae Electric Power Co., Ltd. Power generation KOREA 34.00 % 204,000 220,727 Global Trade Of Power System Co., Ltd. Exporting products and technology of small or medium business by proxy KOREA 29.00 % 290 577 Expressway Solar-light Power Generation Co., Ltd. Power generation KOREA 29.00 % 1,856 2,463 KODE NOVUS I LLC Power generation USA 50.00 % 19,213 — KODE NOVUS II LLC Power generation USA 50.00 % 12,756 — Daejung Offshore Wind Power Co., Ltd. Power generation KOREA 49.90 % 5,190 2,969 Amman Asia Electric Power Power generation JORDAN 60.00 % 111,476 145,676 KAPES, Inc.(*6) R&D KOREA 51.00 % 5,629 7,476 Dangjin Eco Power Co., Ltd. Power generation KOREA 34.00 % 61,540 57,928 Honam Wind Power Co., Ltd. Power generation KOREA 29.00 % 3,480 4,302 Chun-cheon Energy Co., Ltd. Power generation KOREA 29.90 % 52,700 48,118 Yeonggwangbaeksu Wind Power Co., Ltd.(*3) Power generation KOREA 15.00 % 3,000 2,734 Nghi Son 2 Power Ltd. Power generation VIETNAM 50.00 % 2,781 183 Kelar S.A(*6) Power generation CHILE 65.00 % 77,220 67,233 PT. Tanjung Power Indonesia Power generation INDONESIA 35.00 % 746 1,776 Incheon New Power Co., Ltd. Power generation KOREA 29.00 % 461 619 Seokmun Energy Co., Ltd. Power generation KOREA 29.00 % 15,370 13,786 Daehan Wind Power PSC Power generation JORDAN 50.00 % 285 — Barakah One Company(*13) Power generation UAE 18.00 % 118 626 Nawah Energy Company(*13) Operation of utility plant UAE 18.00 % 296 258 MOMENTUM International thermonuclear experimental reactor construction management FRANCE 33.33 % 1 391 Daegu Green Power Co., Ltd. Power generation KOREA 29.00 % 46,225 42,391 Yeonggwang Wind Power Co., Ltd. Power generation KOREA 41.00 % 15,375 15,294 Chester Solar IV SpA(*6) Power generation CHILE 81.82 % 1,700 1,700 Chester Solar V SpA(*6) Power generation CHILE 81.82 % 525 525 Diego de Almagro Solar SpA(*6) Power generation CHILE 81.82 % 2,091 2,091 South Jamaica Power Company Limited Power generation JAMAICA 20.00 % 7,090 6,704 1,469,978 1,493,275 ￦ 3,710,739 5,330,696 (*1) The effective percentage of ownership is 21.57% considering treasury stocks. (*2) The Company can exercise significant influence by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors. (*3) The Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity. (*4) The Company can exercise significant influence by virtue of its contractual right to appoint one out of four members of the steering committee of the entity. Moreover, the Company has significant financial transactions, which can affect its influence on the entity. (*5) The Government regulates the Company’s ability to make operating and financial decisions over the entity, as the Government requires maintaining arms-length transactions between KPX and the Company’s other subsidiaries. The Company can exercise significant influence by its right to nominate directors to the board of directors of the entity. (*6) According to the shareholders’ agreement, all critical financial and operating decisions must be agreed to by all ownership parties. For these reasons, the entities are classified as joint ventures. (*7) As of reporting date, the annual reporting period of all associates and joint ventures ends on December 31, except for Pioneer Gas Power Limited whose reporting period ends on March 31. (*8) As of December 31, 2017, 15.64% of ownership of Hyundai Energy Co., Ltd. is held by NH Power ll Co., Ltd. and NH Bank. According to the shareholders’ agreement reached on March 2011, not only does the Company have a call option to acquire the investment in Hyundai Energy Co., Ltd. from NH Power ll Co., Ltd. and NH Bank with a certain rate of return, NH Power ll Co., Ltd. and NH Bank also have put options to dispose of their investment to the Company. In connection with this agreement, the Company applied the equity method on the investment in Hyundai Energy Co., Ltd. with 46.30% of ownership. (*9) The Company’s percentage of ownership has decreased due to the acquisition of Daeryun Power Co., Ltd. and the effective percentage of ownership is 19.45% considering stock purchase options. (*10) The Company’s effective percentage of ownership excluding the redeemable convertible preferred stock is 25.54%. (*11) The effective percentage of ownership is less than 20% but the Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity and the fact that the dominant portion of the investee’s sales transactions is generated from the Company. (*12) The effective percentage of ownership is more than 50% but the Company does not hold control over relevant business while it exercises significant influence by participating in the Investment Decision Committee. For this reason, the entity is classified as an associate. (*13) The effective percentage of ownership is less than 20% but the Company has joint control over the entity as decisions on the major activities require the unanimous consent of the parties that collectively control the entity (*14) The percentage of ownership decreased since the Company did not participate in the capital increase of Green Biomass Co., Ltd. during the period. (*15) The effective percentage of ownership is more than 50% but the Company does not hold control over the entity according to the shareholders’ agreement. For this reason, the entity is classified as an associate. (2) The fair value of associates which are actively traded on the open market and have a readily available market value as of December 31, 2016 and 2017 are as follows: Investees 2016 2017 In millions of won <Associates> Korea Electric Power Industrial Development Co., Ltd. ￦ 45,474 38,667 Korea Gas Corporation(*) 915,705 804,195 YTN Co., Ltd. 22,320 18,855 SPC Power Corporation 70,253 72,616 PT. Bayan Resources TBK 359,200 558,267 (*) The carrying amount of Korea Gas Corporation (“KOGAS”) is ￦1,618,868 million as of December 31, 2017 and management has determined that there is objective evidence of impairment. As a result of the impairment test, the Company has not recognized any impairment loss as the value in use is greater than the carrying amount. The recoverable amount of KOGAS based on its value in use is calculated by considering the long-term natural gas supply and demand programs of future cash flows approved by Ministry of Trade, Industry & Energy and the discount rate of 4.94%. (3) Changes in investments in associates and joint ventures for the years ended December 31, 2016 and 2017 are as follows: 2016 Investees Beginning Acquisition Disposal Dividends Share of Other Others Ending In millions of won <Associates> Daegu Green Power Co., Ltd. ￦ 80,267 3,347 (34,422 ) — (1,814 ) 148 (47,526 ) — Korea Gas Corporation 2,102,813 — — (3,213 ) (146,308 ) (14,551 ) (4,864 ) 1,933,877 Korea Electric Power Industrial Development Co., Ltd. 18,994 — — (1,598 ) 4,491 — (1,412 ) 20,475 YTN Co., Ltd. 38,365 — — — (227 ) 32 (14 ) 38,156 Cheongna Energy Co., Ltd. 19,490 — — — (7,117 ) — — 12,373 Gangwon Wind Power Co., Ltd. 12,890 — — (1,136 ) 1,270 45 — 13,069 Hyundai Green Power Co., Ltd. 113,664 — — (8,888 ) 11,222 — — 115,998 Korea Power Exchange 208,735 — — — 15,847 — (1,344 ) 223,238 AMEC Partners Korea Ltd. 230 — — — (5 ) — — 225 Hyundai Energy Co., Ltd. 6,990 — — — (21,163 ) — 15,204 1,031 Ecollite Co., Ltd. — — — — — — — — Taebaek Wind Power Co., Ltd. 4,956 — — — (206 ) — — 4,750 Taeback Guinemi Wind Power Co., Ltd. 2,587 570 — — (26 ) — — 3,131 Pyeongchang Wind Power Co., Ltd. 3,402 — — — (19 ) — — 3,383 Daeryun Power Co., Ltd. 36,156 — — — (6,282 ) (1 ) — 29,873 JinanJangsu Wind Power Co., Ltd. 77 — (64 ) — (13 ) — — — Changjuk Wind Power Co., Ltd. 6,143 — — (190 ) 977 — — 6,930 KNH Solar Co., Ltd. 1,924 — — — 144 5 — 2,073 SPC Power Corporation 58,033 — — (7,151 ) 6,416 (477 ) (3 ) 56,818 Gemeng International Energy Co., Ltd. 728,396 — — (16,476 ) 26,714 (58,493 ) (76 ) 680,065 PT. Cirebon Electric Power 60,574 — — (1,242 ) 31,511 2,568 3,247 96,658 KNOC Nigerian East Oil Co., Ltd. — — — — (1,346 ) (398 ) 1,744 — KNOC Nigerian West Oil Co., Ltd. — — — — (973 ) (356 ) 1,329 — Dolphin Property Limited 61 — — (35 ) — (69 ) 43 — PT Wampu Electric Power 18,963 — — — 3,493 (3 ) 735 23,188 PT. Bayan Resources TBK(*2) 525,066 — — — (23,257 ) 208 (99,350 ) 402,667 S-Power 130,908 — — — (7,006 ) — 10 123,912 Pioneer Gas Power Limited 51,187 — — — (698 ) 251 — 50,740 Eurasia Energy Holdings — — — — — — — — Xe-Pian Xe-Namnoy 31,863 16,402 — — 1,576 1,703 — 51,544 Busan Solar Co., Ltd. 925 — (887 ) — (38 ) — — — Hadong Mineral Fiber Co., Ltd. — — — — — — — — Green Biomass Co., Ltd. — — — — (138 ) — 185 47 PT. Mutiara Jawa — — — — — — — — Samcheok Eco Materials Co., Ltd. — — — — — — — — Noeul Green Energy Co., Ltd. 295 1,340 — — (418 ) — — 1,217 Naepo Green Energy Co., Ltd. 26,746 — — — (1,308 ) — — 25,438 Goseong Green Energy Co., Ltd. 2,670 — — — 71 — (78 ) 2,663 Gangneung Eco Power Co., Ltd. 2,688 — — — 56 — (98 ) 2,646 Shin Pyeongtaek Power Co., Ltd. — — — — — — — — Heang Bok Do Si Photovoltaic Power Co., Ltd. 189 — — — (10 ) — 2 181 DS POWER Co., Ltd. 10,960 — — — (3,738 ) — (32 ) 7,190 Dongducheon Dream Power Co., Ltd. 55,667 — — — (8,757 ) — (34 ) 46,876 KS Solar Co., Ltd. 618 — — — (14 ) — — 604 Yeongwol Energy Station Co., 1,290 — — — 85 25 (1,400 ) — Jinbhuvish Power Generation Pvt. Ltd.(*3) ￦ 8,350 — — — (49 ) (198 ) (8,103 ) — SE Green Energy Co., Ltd. 3,575 — — — (50 ) — — 3,525 Daegu Photovoltaic Co., Ltd. 1,886 — — (411 ) 225 — — 1,700 Jeongam Wind Power Co., Ltd. 702 3,900 — — (602 ) — — 4,000 Korea Power Engineering Service Co., Ltd. 1,805 — — — 1,005 — — 2,810 Busan Green Energy Co., Ltd. 14,512 — — — (709 ) — — 13,803 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 904 — — — (904 ) — — — Korea Electric Vehicle Charging Service 1,446 — — — (343 ) — — 1,103 Ulleungdo Natural Energy Co., Ltd. 7,417 — — — (516 ) — (7 ) 6,894 Korea Nuclear Partners Co., Ltd. 289 — — — (41 ) — — 248 Tamra Offshore Wind Power Co., Ltd. — 8,910 — — (1,895 ) — — 7,015 Korea Electric Power Corporation Fund — 51,500 — — (644 ) — — 50,856 Energy Infra Asset Management Co., Ltd. — 297 — — (38 ) — — 259 Daegu clean Energy Co., Ltd. — 140 — — — — — 140 YaksuESS Co., Ltd — 210 — — (14 ) — — 196 Nepal Water & Energy Development Company Private Limited — — — — — — 18,667 18,667 4,405,668 86,616 (35,373 ) (40,340 ) (131,583 ) (69,561 ) (123,175 ) 4,092,252 <Joint ventures> KEPCO-Uhde Inc.(*4) 8,549 — — — (159 ) — (8,089 ) 301 Eco Biomass Energy Sdn. Bhd. — — — — — — — — Datang Chaoyang Renewable Power Co., Ltd. 27,640 — — — 1,417 (818 ) — 28,239 Shuweihat Asia Power Investment B.V. 20,474 — (14,154 ) (2,957 ) 6,131 (9,494 ) — — Shuweihat Asia Operation & Maintenance Company 486 — — (931 ) 941 (46 ) — 450 Waterbury Lake Uranium L.P. 20,299 — — — — 1,138 (123 ) 21,314 ASM-BG 20,203 — — — 1,508 (223 ) — 21,488 RES Technology AD 13,789 — — — (68 ) (139 ) — 13,582 KV Holdings, Inc. 2,010 — — (302 ) 429 (39 ) — 2,098 KEPCO SPC Power Corporation 208,524 — — (5,955 ) 48,132 (5,308 ) (26 ) 245,367 Canada Korea Uranium Limited Partnership — — — — — — — — Gansu Datang Yumen Wind Power Co., Ltd. 16,107 — — — (2,836 ) (450 ) — 12,821 Datang Chifeng Renewable Power Co., Ltd. 171,224 — — (7,384 ) 7,455 (4,760 ) — 166,535 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 10,580 — — (440 ) 1,002 (299 ) — 10,843 Rabigh Electricity Company 59,368 — — — 18,961 19,473 — 97,802 Rabigh Operation & Maintenance Company Limited 3,586 — — (1,934 ) 2,253 229 293 4,427 Jamaica Public Service Company Limited 241,918 — — — — 7,535 — 249,453 KW Nuclear Components Co., Ltd. 4,985 — — (2,191 ) 4,344 — (5 ) 7,133 Busan Shinho Solar Power Co., Ltd. 3,678 — — (185 ) 321 — — 3,814 GS Donghae Electric Power Co., Ltd. 200,379 — — — 5,575 — (6 ) 205,948 Global Trade Of Power System Co., Ltd. ￦ 426 — — — 51 — — 477 Expressway Solar-light Power Generation Co., Ltd. 2,100 — — — 243 — — 2,343 KODE NOVUS I LLC — — — — — — — — KODE NOVUS II LLC — 258 — — (260 ) — 2 — Daejung Offshore Wind Power Co., Ltd. 3,352 — — — (337 ) — — 3,015 Amman Asia Electric Power Company 137,668 — — (12,684 ) 17,811 11,062 — 153,857 KAPES, Inc. 4,501 — — — 311 — (54 ) 4,758 Dangjin Eco Power Co., Ltd. 48,281 5,100 — — (696 ) (26 ) 594 53,253 Honam Wind Power Co., Ltd. 3,926 — — (104 ) 629 — — 4,451 Nepal Water & Energy Development Company Private Limited 17,765 — — — 359 543 (18,667 ) — Chun-cheon Energy Co., Ltd. 31,976 19,832 — — (1,121 ) (95 ) — 50,592 Yeonggwangbaeksu Wind Power Co., Ltd. 2,668 — — — 16 — 5 2,689 Nghi Son 2 Power Ltd. 269 716 — — (740 ) (16 ) — 229 Kelar S.A — — — — — — — — PT. Tanjung Power Indonesia 617 — — — 1,337 — (8 ) 1,946 Incheon New Power Co., Ltd. 514 — — — 41 8 — 563 Seokmun Energy Co., Ltd. — — — — (197 ) 793 (205 ) 391 Daehan Wind Power PSC — 285 — — (261 ) (8 ) — 16 Barakah One Company — 118 — — — — (2 ) 116 Nawah Energy Company — 296 — — — — (6 ) 290 MOMENTUM — 1 — — 65 — 1 67 Daegu Green Power Co., Ltd. — — — — — — 47,528 47,528 1,287,862 26,606 (14,154 ) (35,067 ) 112,657 19,060 21,232 1,418,196 ￦ 5,693,530 113,222 (49,527 ) (75,407 ) (18,926 ) (50,501 ) (101,943 ) 5,510,448 (*1) ‘Others’ include ￦1,400 million of assets held-for-sale (*2) It was determined that there is objective evidence of impairment due to prolonged operating losses. As a result, the Company recognized an impairment loss of ￦99,338 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2016. (*3) Due to discontinuation of operations during the year ended December 31, 2016, the Company recognized an impairment loss of ￦8,103 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2016. (*4) It was determined that there is objective evidence of impairment due to prolonged operating losses. As a result, the Company recognized an impairment loss of ￦8,099 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2016. 2017 Investees Beginning Acquisition Disposal Dividends Share of Other Others Ending In millions of won <Associates> Kore

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	18. Property, Plant and Equipment (1) Property, plant and equipment as of December 31, 2016 and 2017 are as follows: 2016 Acquisition cost Government grants Accumulated depreciation Accumulated losses(*) Book value In millions of won Land ￦ 12,969,741 (3,204 ) — — 12,966,537 Buildings 17,722,326 (61,188 ) (5,936,849 ) (853 ) 11,723,436 Structures 63,291,437 (197,641 ) (19,959,839 ) (1,183 ) 43,132,774 Machinery 67,769,168 (111,064 ) (24,344,832 ) (2,391 ) 43,310,881 Ships 4,175 — (3,625 ) — 550 Vehicles 247,751 (107 ) (176,781 ) — 70,863 Equipment 1,270,660 (732 ) (894,265 ) — 375,663 Tools 921,115 (430 ) (742,083 ) — 178,602 Construction-in- 27,334,368 (135,807 ) — (38,108 ) 27,160,453 Finance lease assets 2,390,779 — (1,984,426 ) — 406,353 Asset retirement costs 7,129,771 — (3,064,359 ) — 4,065,412 Others 10,361,294 — (8,009,762 ) — 2,351,532 ￦ 211,412,585 (510,173 ) (65,116,821 ) (42,535 ) 145,743,056 (*) The Company separately recognizes impairment loss on each asset, reflecting various factors such as physical impairment and others during the replacement. 2017 Acquisition cost Government grants Accumulated depreciation Accumulated losses(*) Book value In millions of won Land ￦ 13,318,542 (21,968 ) — — 13,296,574 Buildings 18,777,678 (63,539 ) (6,722,376 ) (1,776 ) 11,989,987 Structures 66,184,484 (196,414 ) (22,071,667 ) (8,039 ) 43,908,364 Machinery 75,826,292 (183,188 ) (28,904,982 ) (45,512 ) 46,692,610 Ships 4,175 — (3,772 ) — 403 Vehicles 276,425 (6,322 ) (195,260 ) (127 ) 74,716 Equipment 1,440,870 (761 ) (1,020,192 ) (6 ) 419,911 Tools 1,010,537 (1,027 ) (809,842 ) (32 ) 199,636 Construction-in-progress 25,610,649 (49,084 ) — (38,108 ) 25,523,457 Finance lease assets 2,390,680 (27 ) (2,093,001 ) — 297,652 Asset retirement costs 9,395,821 — (3,356,337 ) — 6,039,484 Others 11,247,021 — (8,807,401 ) — 2,439,620 ￦ 225,483,174 (522,330 ) (73,984,830 ) (93,600 ) 150,882,414 (*) The Company separately recognizes impairment loss on each asset, reflecting various factors such as physical impairment and others during the replacement. (2) Changes in property, plant and equipment for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Acquisition Disposal Depreciation Impairment Others Ending balance In millions of won Land ￦ 12,396,460 13,973 (52,569 ) — — 611,877 12,969,741 (Government grants) (3,147 ) — 14 — — (71 ) (3,204 ) Buildings 9,676,432 — (9,020 ) (676,866 ) — 2,794,078 11,784,624 (Government grants) (63,932 ) — 731 5,299 — (3,286 ) (61,188 ) Structures 40,258,162 455 (524,310 ) (2,233,333 ) — 5,829,441 43,330,415 (Government grants) (193,119 ) — 2,597 9,491 — (16,610 ) (197,641 ) Machinery 36,864,749 193,017 (243,757 ) (4,353,596 ) — 10,961,532 43,421,945 (Government grants) (108,935 ) (33 ) 1,210 12,272 — (15,578 ) (111,064 ) Ships 786 — — (281 ) — 45 550 Vehicles 60,472 2,493 (34 ) (27,615 ) — 35,654 70,970 (Government grants) (29 ) (58 ) — 25 — (45 ) (107 ) Equipment 310,571 67,134 (323 ) (128,084 ) — 127,097 376,395 (Government grants) (1,026 ) — — 452 — (158 ) (732 ) Tools 160,630 27,856 (327 ) (69,842 ) — 60,715 179,032 (Government grants) (691 ) — — 295 — (34 ) (430 ) Construction-in-progress 35,267,026 11,752,352 (94,443 ) — — (19,628,675 ) 27,296,260 (Government grants) (139,898 ) (28,434 ) — — — 32,525 (135,807 ) Finance lease assets 511,509 34 (31 ) (96,254 ) — (8,905 ) 406,353 Asset retirement costs 4,106,087 — — (509,310 ) — 468,635 4,065,412 Others 2,259,244 — (9 ) (813,248 ) — 905,545 2,351,532 ￦ 141,361,351 12,028,789 (920,271 ) (8,880,595 ) — 2,153,782 145,743,056 2017 Beginning Acquisition Disposal Depreciation Impairment( ) Others Ending balance In millions of won Land ￦ 12,969,741 32,773 (8,961 ) — — 324,989 13,318,542 (Government grants) (3,204 ) — 5 — — (18,769 ) (21,968 ) Buildings 11,784,624 40,592 (19,715 ) (794,804 ) (923 ) 1,043,752 12,053,526 (Government grants) (61,188 ) (900 ) 28 5,996 — (7,475 ) (63,539 ) Structures 43,330,415 428 (519,366 ) (2,421,168 ) (6,856 ) 3,721,325 44,104,778 (Government grants) (197,641 ) — 1,905 10,011 — (10,689 ) (196,414 ) Machinery 43,421,945 421,892 (242,428 ) (4,821,595 ) (43,121 ) 8,139,105 46,875,798 (Government grants) (111,064 ) (10,834 ) 489 17,390 — (79,169 ) (183,188 ) Ships 550 — — (147 ) — — 403 Vehicles 70,970 3,447 (174 ) (34,236 ) (127 ) 41,158 81,038 (Government grants) (107 ) (107 ) 14 1,070 — (7,192 ) (6,322 ) Equipment 376,395 53,529 (413 ) (158,614 ) (6 ) 149,781 420,672 (Government grants) (732 ) (43 ) — 454 — (440 ) (761 ) Tools 179,032 30,990 (166 ) (74,909 ) (32 ) 65,748 200,663 (Government grants) (430 ) — — 354 — (951 ) (1,027 ) Construction-in-progress 27,296,260 11,996,508 (6,487 ) — — (13,713,740 ) 25,572,541 (Government grants) (135,807 ) (42,728 ) — — — 129,451 (49,084 ) Finance lease assets 406,353 — (29,696 ) (107,390 ) — 28,412 297,679 (Government grants) — — — 1 — (28 ) (27 ) Asset retirement costs 4,065,412 — — (518,565 ) — 2,492,637 6,039,484 Others 2,351,532 10,411 (28 ) (762,711 ) — 840,416 2,439,620 ￦ 145,743,056 12,535,958 (824,993 ) (9,658,863 ) (51,065 ) 3,138,321 150,882,414 (*) Korea Midland Power Co., Ltd. and Korea Western Power Co., Ltd., 100% owned subsidiaries, have determined that there are impairment indicators for the shutdowns of certain power generation units and fire, and performed an impairment test over the individual assets. As a result, the Company recognized the amount of the carrying amount in excess of its recoverable amount as impairment loss in the consolidated statements of comprehensive income.

Investment Properties

Investment Properties	12 Months Ended
	Dec. 31, 2017
Investment Properties [Abstract]
Investment Properties	19. Investment Properties (1) Investment properties as of December 31, 2016 and 2017 are as follows: 2016 Acquisition cost Government grants Accumulated Book value In millions of won Land ￦ 336,421 — — 336,421 Buildings 29,168 (64 ) (11,845 ) 17,259 ￦ 365,589 (64 ) (11,845 ) 353,680 2017 Acquisition cost Government grants Accumulated Book value In millions of won Land ￦ 264,205 — — 264,205 Buildings 36,165 (83 ) (15,573 ) 20,509 ￦ 300,370 (83 ) (15,573 ) 284,714 (2) Changes in investment properties for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning balance Depreciation Others Ending balance In millions of won Land ￦ 253,960 — 82,461 336,421 Buildings 15,963 (679 ) 2,039 17,323 (Government grants) (13 ) 1 (52 ) (64 ) ￦ 269,910 (678 ) 84,448 353,680 2017 Beginning balance Depreciation Others Ending balance In millions of won Land ￦ 336,421 — (72,216 ) 264,205 Buildings 17,323 (1,178 ) 4,447 20,592 (Government grants) (64 ) 2 (21 ) (83 ) ￦ 353,680 (1,176 ) (67,790 ) 284,714 (3) Income and expenses related to investment properties for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Rental income ￦ 9,460 9,581 Operating and maintenance expenses related to rental income (678 ) (1,172 ) ￦ 8,782 8,409 (4) Fair value of investment properties as of December 31, 2016 and 2017 are as follows: 2016 2017 Book value Fair value Book value Fair value In millions of won Land ￦ 336,421 374,042 264,205 309,241 Buildings 17,259 20,708 20,509 23,319 ￦ 353,680 394,750 284,714 332,560 The fair values of the investment properties as of the reporting date were determined in consideration of the fluctuation on the publicly announced individual land price after the IFRS transition date (January 1, 2010). (5) All of the Company’s investment property is held under freehold interests.

Construction Services Contracts

Construction Services Contracts	12 Months Ended
	Dec. 31, 2017
Construction Services Contracts [Abstract]
Construction Services Contracts	20. Construction Services Contracts (1) Changes in total contract amount in which revenue is not yet recognized for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 Beginning balance Increase (decrease)(*) Recognized as revenue Ending In millions of won Nuclear power plant construction in UAE and others ￦ 17,081,074 (1,011,031 ) (3,761,204 ) 12,308,839 (*) For the year ended December 31, 2015, the increased balance of contracts from new orders and other is ￦412,617 million and the decreased balance of contracts due to changes in scope of construction work is ￦1,423,648 million. 2016 Beginning balance Increase (decrease)(*) Recognized as revenue Ending In millions of won Nuclear power plant construction in UAE and others ￦ 12,308,839 (1,045,094 ) (4,026,857 ) 7,236,888 (*) For the year ended December 31, 2016, the increased balance of contracts from new orders and other is ￦718,118 million and the decreased balance of contracts due to changes in scope of construction work is ￦1,763,212 million. 2017 Beginning balance Increase (decrease)(*) Recognized as revenue Ending In millions of won Nuclear power plant construction in UAE and others ￦ 7,236,888 151,891 (3,212,184 ) 4,176,595 (*) For the year ended December 31, 2017, the increased balance of contracts from new orders and other is ￦438,142 million and the decreased balance of contracts due to changes in scope of construction work is ￦286,251 million. (2) Accumulated earned revenue, expense and others related to the Company’s construction contracts as of December 31, 2016 and 2017 are as follows: 2016 Accumulated earned revenue Accumulated expense Accumulated profit Unearned advance receipts In millions of won Nuclear power plant construction in UAE and others ￦ 15,314,737 14,396,890 917,847 — 2017 Accumulated earned revenue Accumulated expense Accumulated profit Unearned advance receipts In millions of won Nuclear power plant construction in UAE and others ￦ 18,236,992 16,937,772 1,299,220 — (3) Gross amount due from customers recognized as assets and due to customers recognized as liabilities for contract work as of December 31, 2016 and 2017 are as follows: 2016 2017 Assets(*1) Liabilities(*2) Assets(*1) Liabilities(*2) In millions of won Nuclear power plant construction in UAE and others ￦ 44,930 651,985 55,755 542,921 (*1) Included in trade and other receivables, net, in the consolidated statements of financial position. (*2) Included in non-financial

Intangible Assets other than Go

Intangible Assets other than Goodwill	12 Months Ended
	Dec. 31, 2017
Intangible Assets other than Goodwill [Abstract]
Intangible Assets other than Goodwill	21. Intangible Assets other than Goodwill (1) Intangible assets as of December 31, 2016 and 2017 are as follows: 2016 Acquisition Government Accumulated Accumulated Book value In millions of won Software ￦ 458,382 (595 ) (365,161 ) — 92,626 Licenses and franchises 3,398 — (3,398 ) — — Copyrights, patents rights and other industrial rights 35,756 — (15,675 ) — 20,081 Mining rights 549,371 — (10,511 ) — 538,860 Development expenditures 785,966 (5,152 ) (723,561 ) — 57,253 Intangible assets under Development 119,474 (11,090 ) — (3,941 ) 104,443 Usage rights of donated assets and other 426,346 (21 ) (342,244 ) — 84,081 Leasehold rights 23,350 — (18,718 ) — 4,632 Greenhouse gas emissions rights 6,283 — — — 6,283 Others 173,213 — (88,527 ) (12,124 ) 72,562 ￦ 2,581,539 (16,858 ) (1,567,795 ) (16,065 ) 980,821 2017 Acquisition Government Accumulated Accumulated Book value In millions of won Software ￦ 534,191 (486 ) (408,300 ) — 125,405 Licenses and franchises 3,398 — (3,398 ) — — Copyrights, patents rights and other industrial rights 43,857 — (19,876 ) — 23,981 Mining rights 553,876 — (14,243 ) — 539,633 Development expenditures 836,996 (3,702 ) (752,478 ) — 80,816 Intangible assets under development 143,851 (10,540 ) — (3,941 ) 129,370 Usage rights of donated assets and other 459,682 (11 ) (358,024 ) — 101,647 Leasehold rights 24,306 — (19,262 ) — 5,044 Others 297,289 — (103,995 ) (12,069 ) 181,225 ￦ 2,897,446 (14,739 ) (1,679,576 ) (16,010 ) 1,187,121 (2) Changes in intangible assets for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Acquisition Disposal Amortization Impairment Others Ending In millions of won Software ￦ 57,886 18,267 — (32,378 ) — 49,446 93,221 (Government grants) (699 ) — — 249 — (145 ) (595 ) Copyrights, patents rights and other industrial rights 21,875 85 (39 ) (2,697 ) — 857 20,081 Mining rights 499,537 26,311 — (899 ) — 13,911 538,860 Development expenditures 51,807 212 — (21,993 ) — 32,379 62,405 (Government grants) (6,835 ) — — 2,771 — (1,088 ) (5,152 ) Intangible assets under development 94,886 66,588 — — (3,945 ) (41,996 ) 115,533 (Government grants) (10,483 ) (1,597 ) — — — 990 (11,090 ) Usage rights of donated assets and other 48,591 — — (15,513 ) — 51,024 84,102 (Government grants) (32 ) — — 11 — — (21 ) Leasehold rights 745 — — (351 ) — 4,238 4,632 Greenhouse gas emissions rights 805 6,283 — — — (805 ) 6,283 Others 97,750 8,273 (550 ) (8,916 ) 3 (23,998 ) 72,562 (Government grants) (1 ) — — 1 — — — ￦ 855,832 124,422 (589 ) (79,715 ) (3,942 ) 84,813 980,821 2017 Beginning Acquisition Disposal Amortization Impairment Others Ending In millions of won Software ￦ 93,221 12,700 (5 ) (44,809 ) — 64,784 125,891 (Government grants) (595 ) (17 ) — 255 — (129 ) (486 ) Copyrights, patents rights and other industrial rights 20,081 30 (7 ) (3,350 ) — 7,227 23,981 Mining rights 538,860 26,751 (272 ) (4,640 ) — (21,066 ) 539,633 Development expenditures 62,405 494 — (25,924 ) — 47,543 84,518 (Government grants) (5,152 ) — — 2,811 — (1,361 ) (3,702 ) Intangible assets under development 115,533 56,527 — — (20 ) (32,130 ) 139,910 (Government grants) (11,090 ) — — — — 550 (10,540 ) Usage rights of donated assets and other 84,102 — — (14,462 ) — 32,018 101,658 (Government grants) (21 ) — — 10 — — (11 ) Leasehold rights 4,632 — — (545 ) — 957 5,044 Greenhouse gas emissions rights 6,283 — — — — (6,283 ) — Others 72,562 47,402 (377 ) (23,018 ) 54 84,602 181,225 (Government grants) — — — — — — — ￦ 980,821 143,887 (661 ) (113,672 ) 34 176,712 1,187,121 (3) Significant specific intangible assets as of December 31, 2016 and 2017 are as follows: 2016 Type Description Currency Amount Remaining useful years In millions of won and thousands of Australian dollars Software ERP system and others KRW 506 11 months ~ 1 year and 11 months SCADA O/S (POWERON RELIANCE) KRW 4,206 3 years and 1 month Copyrights, patents rights and other industrial rights Smart technology verification and standard design project conducting right KRW 5,750 5 years and 9 months Mining rights Mining right of Bylong mine AUD 401,225 — (*) Development expenditures Development of maintenance system for utility plant KRW 518 11 months Intangible assets under development Contributions to ARP NRC DC KRW 41,190 — Usage rights of donated assets and others Sejong Haengbogdosi sharing charge KRW 44,502 9 years and 11 months Dangjin power plant load facility usage right KRW 26,759 4 years and 3 months Others Sillim electricity supply facility usage right KRW 2,196 4 years and 11 months (*) Mining rights are amortized using the units-of-production 2017 Type Description Currency Amount Remaining useful lives millions of won and thousands of Australian dollars Software ERP system and others KRW 1,135 3 years and 2 months ~ 3 years and 4 months AMI GATEWAY S/W KRW 3,528 3 years and 2 months Copyrights, patents rights and other industrial rights Smart technology verification and standard design project conducting right KRW 11,724 4 years and 9 months Mining rights Mining right of Bylong mine AUD 401,225 — (*) Development expenditures Electricity sales information system KRW 29,391 4 years 3 months Intangible assets under development Contributions to ARP NRC DC KRW 46,458 — Usage rights of donated assets and others Sejong Haengbogdosi sharing charge KRW 40,460 8 years and 11 months Dangjin power plant load facility usage right KRW 20,463 3 years 3 months Others Occupancy and use of public waters KRW 103,269 18 years 11 months (*) Mining rights are amortized using the units-of-production (4) For the years ended December 31, 2015, 2016 and 2017, the Company recognized research and development expenses of 611,220 million, 705,504 million and 721,437 million, respectively.

Trading liabilities

Trading liabilities	12 Months Ended
	Dec. 31, 2017
Trade and Other Payables [Abstract]
Trade and Other Payables	22. Trade and Other Payables Trade and other payables as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Trade payables ￦ 2,610,373 — 2,936,990 — Other trade payables 1,498,582 3,033,780 1,649,933 2,825,039 Accrued expenses 1,152,933 2,161 1,087,844 1,951 Leasehold deposits received 1,426 1,008 1,562 1,308 Other deposits received 197,711 93,751 186,817 102,896 Finance lease liabilities 121,176 420,003 131,792 286,468 Dividends payable 3,204 — 4,448 — Others (*) 6 7,472 135 5,818 ￦ 5,585,411 3,558,175 5,999,521 3,223,480 (*) Details of others as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Advance received from local governments ￦ — 7,472 — 5,818 Others 6 — 135 — ￦ 6 7,472 135 5,818

Borrowings and Debt Securities

Borrowings and Debt Securities	12 Months Ended
	Dec. 31, 2017
Borrowings and Debt Securities [Abstract]
Borrowings and Debt Securities	23. Borrowings and Debt Securities (1) Borrowings and debt securities as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Current liabilities Short-term borrowings ￦ 805,523 1,038,328 Current portion of long-term borrowings 310,977 128,543 Current portion of debt securities 7,825,310 7,961,182 Less : Current portion of discount on long-term borrowings (979 ) (886 ) Less : Current portion of discount on debt securities (1,753 ) (3,882 ) 8,939,078 9,123,285 Non-current Long-term borrowings 1,799,750 2,455,737 Debt securities 43,012,960 43,270,825 Less : Discount on long-term borrowings (25,859 ) (21,113 ) Less : Discount on debt securities (86,880 ) (81,424 ) Add: Premium on debt securities 156 82 44,700,127 45,624,107 ￦ 53,639,205 54,747,392 (2) Repayment schedule of borrowings and debt securities as of December 31, 2016 and 2017 are as follows: 2016 Type Borrowings Debt Securities In millions of won Less than 1 year ￦ 1,116,500 7,825,310 1~ 5 years 295,162 24,462,410 Over 5 years 1,504,588 18,550,550 ￦ 2,916,250 50,838,270 2017 Type Borrowings Debt Securities In millions of won Less than 1 year ￦ 1,166,871 7,961,182 1~ 5 years 1,117,222 25,047,075 Over 5 years 1,338,515 18,223,750 ￦ 3,622,608 51,232,007 23. Borrowings and Debt Securities (3) Short-term borrowings as of December 31, 2016 and 2017 are as follows: 2016 Type Creditor Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local short-term borrowings Woori Investment Bank and others 1.54~2.51 2017.01.25~ 2017.09.13 — ￦ 436,800 Foreign short-term borrowings SCNT and others 1.58~6.50 2017.03.30~ 2017.12.03 USD 35,086 42,401 Foreign short-term borrowings Export-import Bank of Korea 3M 2017.05.17~ 2017.12.18 AUD 311,174 271,360 Local bank overdraft Nonghyup Bank 2.45 2017.01.05 — 37,000 Local bank overdraft Woori Bank Standard overdraft 2017.02.25 — 17,962 ￦ 805,523 2017 Type Creditor Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local short-term borrowings KTB Investment and securities and others 1.57~2.47 2018.01.12~ 2018.09.19 — ￦ 686,561 Foreign short-term borrowings SCNT and others 4.60~6.50 2018.12.03 USD 8,955 9,594 Foreign short-term Export-import Bank of Korea 3M 2018.12.18 AUD 327,259 273,314 Local bank overdraft Nonghyup Bank 3.04 2018.01.02 51,300 Local bank overdraft Woori Bank Standard overdraft 2018.02.27 — 17,559 ￦ 1,038,328 (4) Long-term borrowings as of December 31, 2016 and 2017 are as follows: 2016 Type Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local long-term borrowings Korea Development Bank Others 0.50 2018~2044 — ￦ 5,663 Facility 2.45~4.60 2023~2028 — 61,835 Facility 1yr KoFC bond rate +0.31 2018 — 125,000 Operating funds 2.75 2018 — 12,000 KEB Hana Bank Commercial Paper 3M CD+0.14 2017 — 100,000 Facility 4.60 2028 — 16,851 Facility 3yr KTB rate -1.25 2017~2028 — 9,655 IBK PF Refinancing CD+1.25 2030 — 22,500 Export-Import Bank of Korea Project loans 1.50 2026 — 30,935 Korea Resources Corporation Development of power resources 3yr KTB rate -2.25 2022~2025 — 14,039 Facility 3yr KTB rate -2.25 2017~2024 — 3,842 Project loans — 2022~2025 — 3,733 Others KTB rate -2.25 2024~2025 — 12,131 Shinhan Bank and others Collateral borrowing 2.22 2017 — 30,000 Facility CB rate+1.10 2028 — 25,276 Operating funds 2.70~2.86 2017~2018 — 25,000 Others 4.10 2035 — 55,000 Others 3yr KTB rate+1.10 2035 — 55,000 Kookmin Bank Facility MOR+0.62~0.79 2017~2023 — 45,000 Others Facility 1.75~4.60 2026~2029 — 146,472 Facility CB rate+1.10~1.20 2022~2028 — 34,951 PF Refinancing 4.10 2030 — 62,500 Others 8.00 2036 — 102,347 Others — 2028 — 7,250 1,006,980 Foreign long-term borrowings Korea National Oil Corporation Project loans — 2021~2023 USD 8,744 10,567 Export-Import Bank of Korea and others Direct loan and others 3M Libor+2.75~ 2027 JOD 178,892 305,332 Commercial loan and others 3M Libor+1.50~ 2030~2033 USD 299,859 362,379 PF Loan 6M Libor+2.50~ 2032 USD 119,647 144,594 SCNT and others Shareholder’s loan 6.50~8.00 2023 USD 40,618 49,086 Shareholder’s loan 8.00 2031 JOD 7,128 12,166 PT PJB Shareholder’s loan 12.75 2019 IDR 16,705,505 1,500 Samsung Life Insurance and others Syndicated Loan 3.10 2032 JPY 1,758,000 18,227 Woori Bank and others Syndicated Loan JPY 6M Libor+2.10 2032 JPY 1,172,000 12,151 SMBC and others Equity Bridge Loan 1M Libor+0.90 2019 USD 37,978 45,897 IFC and others Others 6M Libor+5.00 2031 PKR 11,706,160 134,972 Others Others — 2019 USD 5,691 6,876 1,103,747 2,110,727 Less : Discount of long-term borrowings (26,838 ) Less : Current portion of long-term borrowings (310,977 ) Add : Current portion of discount on long-term borrowings 979 ￦ 1,773,891 2017 Type Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local long-term borrowings Korea Development Bank Others 0.50 2018~2044 — ￦ 4,909 Facility 2.45~4.60 2023~2028 — 68,883 Facility 1yr KoFC bond rate 2018 — 25,000 Operating funds 2.59~3.04 2018~2020 — 47,000 Operating funds 1yr KoFC bond rate +0.95 2020 — 14,000 KEB Hana Bank Commercial Paper 3M CD+0.24~0.32 2021~2022 — 400,000 Facility 4.60 2028 — 15,038 Facility 3yr KTB rate-1.25 2018~2028 — 8,947 IBK PF Refinancing CD+1.25 2030 — 22,500 Export-Import Bank of Korea Project loans 1.50 2026 — 25,042 Operating funds 2.21 2020 — 35,000 Korea Energy Development of power resources 3yr KTB rate-2.25 2023~2025 — 6,765 Facility 3yr KTB rate-2.25 2018~2024 — 3,121 Project loans — 2022~2025 — 3,733 Others KTB rate -2.25 2024~2028 — 18,455 Shinhan Bank Collateral borrowing 2.32 2019 — 30,000 Facility CB rate +1.10 2028 — 22,557 Operating funds 2.70 2018 — 15,000 Others 4.10 2035 — 105,000 Others Standard overdraft 2035 — 105,000 Kookmin Bank Facility 3.16 2020 — 10,000 Facility MOR+0.79 2023 — 35,000 Others Facility 1.75~4.60 2026~2029 — 148,423 Facility CB rate +1.10~1.20 2022~2028 — 46,278 PF Refinancing 4.10 2030 — 62,500 Others 4.50~8.00 2022~2039 — 102,346 1,380,497 Foreign long-term borrowings Korea Energy Project loans — 2021~2023 USD 8,744 9,368 Export-Import Bank of Korea and others Direct loan and others 1M Libor+1.80~3.20 2036 USD 64,913 69,548 Direct loan and others 3M Libor+2.75~3.70 2027 JOD 168,663 254,514 Commercial loan and others 3M Libor+1.50~2.50 2030~2033 USD 289,026 309,662 PF Loan 6M Libor+1.70~2.50 2032 USD 123,253 132,054 SCNT and others Shareholder’s loan 6.50~8.00 2023 USD 41,718 44,697 Shareholder’s loan 8.00 2031 JOD 5,136 7,750 PT PJB Shareholder’s loan 12.75 2019 IDR 10,932,568 864 Samsung Life Insurance and others Syndicated Loan 3.10 2032 JPY 5,325,000 50,540 Woori Bank and others Syndicated Loan JPY 6M Libor+2.00 2032 JPY 3,435,000 32,602 SMBC and others Equity Bridge Loan 1M Libor+0.90 2019 USD 70,986 76,054 IFC and others Others 6M Libor+5.00 2031 PKR 16,652,350 161,195 Federal Financing Bank PF loan 2.39 2031 USD 48,366 51,819 Others Others — 2019 USD 2,907 3,116 1,203,783 2,584,280 Less : Discount of long-term borrowings (21,999 ) Less : Current portion of long-term borrowings (128,543 ) Add : Current portion of discount on long-term borrowings 886 ￦ 2,434,624 (*) As of July 1, 2017, loan business for energy-related projects has been integrated into Korea Energy Agency in accordance with the Korean government’s restructuring of the public institutions. (5) Local debt securities as of December 31, 2016 and 2017 are as follows: Issue date Maturity Interest rate (%) 2016 2017 In millions of won Electricity Bonds 2009.12.03~ 2017.12.14 2018.01.07~ 2037.09.18 1.62~5.45 ￦ 19,860,000 20,700,000 Electricity Bonds 2013.06.25 2018.06.25 3M CD+0.31 310,000 150,000 Corporate Bonds(*1) 2009.05.04~ 2017.11.10 2018.01.18~ 2047.10.17 1.36~5.84 19,552,708 21,122,708 39,722,708 41,972,708 Less : Discount on local debt securities (34,667 ) (37,816 ) Less : Current portion of local debt securities (5,650,010 ) (5,200,000 ) Add : Current portion of discount on local debt securities 728 923 ￦ 34,038,759 36,735,815 (*1) Corporate Bonds of HeeMang Sunlight Power Co., Ltd (￦2,697 million) can be redeemed every March 31 after five years from its issue date, March 31, 2016. (6) Foreign debt securities as of December 31, 2016 and 2017 are as follows: 2016 Type Issue date Maturity Interest rate (%) Foreign currency Local currency In millions of won and thousands of foreign currencies FY-96 1996.04.01~ 1996.12.06 2026.12.06~ 2096.04.01 6.00~8.37 USD 249,068 ￦ 300,999 FY-97 1997.01.31~ 1997.08.04 2027.02.01~ 2027.08.01 6.75~7.00 USD 314,717 380,335 FY-04 2004.04.23 2034.04.23 5.13 USD 286,920 346,743 FY-08 2008.11.27 2018.11.27 4.19 JPY 20,000,000 207,362 FY-11 2011.07.13~ 2011.07.29 2017.01.30~ 2021.07.13 3.63~4.75 USD 800,000 966,800 FY-12 2012.05.10~ 2012.09.19 2017.05.10~ 2022.09.19 2.50~3.13 USD 1,750,000 2,114,875 FY-13 2013.02.05~ 2013.11.27 2018.02.05~ 2018.11.27 1.88~2.88 USD 1,900,000 2,296,150 FY-13 2013.09.26~ 2013.10.23 2019.03.26~ 2019.04.23 1.50~1.63 CHF 400,000 472,532 FY-13 2013.09.25 2020.09.25 5.75 AUD 325,000 283,416 FY-13 2013.02.20~ 2013.07.25 2018.02.20~ 2018.07.25 3M Libor+0.84~1.50 USD 500,000 604,250 FY-14 2014.02.11~ 2014.12.02 2019.02.11~ 2029.07.30 2.38~3.57 USD 1,500,000 1,812,750 FY-14 2014.01.28~ 2014.07.31 2017.01.28~ 2017.07.31 3M Libor+0.55~1.05 USD 500,000 604,250 FY-15 2015.06.15 2025.06.15 3.25 USD 300,000 362,550 FY-16 2016.01.21 2021.07.21 2.50 USD 300,000 362,550 11,115,562 Less : Discount on foreign debt securities (53,966 ) Add : Premium on foreign debt securities 156 Less : Current portion of foreign debt securities (2,175,300 ) Add : Current portion of discount on foreign debt securities 1,025 ￦ 8,887,477 2017 Type Issue date Maturity Interest rate (%) Foreign currency Local currency In millions of won and thousands of foreign currencies FY-96 1996.04.01~ 1996.12.06 2026.12.01~ 2096.04.01 6.00~8.37 USD 249,070 ￦ 266,854 FY-97 1997.01.31~ 1997.08.04 2027.02.01~ 2027.08.01 6.75~7.00 USD 314,717 337,188 FY-04 2004.04.23 2034.04.23 5.13 USD 286,920 307,406 FY-08 2008.11.27 2018.11.27 4.19 JPY 20,000,000 189,822 FY-11 2011.07.13 2021.07.13 4.75 USD 500,000 535,700 FY-12 2012.09.19 2022.09.19 3 USD 750,000 803,550 FY-13 2013.02.05~ 2013.11.27 2018.02.05~ 2018.11.27 1.88~2.88 USD 1,900,000 2,035,660 FY-13 2013.09.26~ 2013.10.23 2019.03.26~ 2019.04.23 1.50~1.63 CHF 400,000 437,888 FY-13 2013.09.25 2020.09.25 5.75 AUD 325,000 271,427 FY-13 2013.02.20~ 2013.07.25 2018.02.20~ 2018.07.25 3M Libor+0.84~1.50 USD 500,000 535,700 FY-14 2014.02.11~ 2014.12.02 2019.02.11~ 2029.07.30 2.38~3.57 USD 1,500,000 1,607,100 FY-15 2015.06.15 2025.06.15 3.25 USD 300,000 321,420 FY-16 2016.01.21 2021.07.21 2.5 USD 300,000 321,420 FY-17 2017.04.12~ 2017.07.25 2020.04.12~ 2027.07.25 2.38~3.13 USD 1,100,000 1,178,540 FY-17 2017.10.30 2037.10.30 1.7 EUR 40,000 51,170 FY-17 2017.11.16 2037.11.16 2.36 SEK 450,000 58,454 9,259,299 Less : Discount on foreign debt securities (47,490 ) Add : Premium on foreign debt securities 82 Less : Current portion of foreign debt securities (2,761,182 ) Add : Current portion of discount on foreign debt securities 2,959 ￦ 6,453,668 (7) Changes in borrowings and debt securities for the year ended December 31, 2017 are as follows: Beginning balance Cash flow Effect of exchange rate Others Ending balance In millions of won 53,639,205 2,269,513 (1,169,418) 8,092 54,747,392

Finance Lease Liabilities

Finance Lease Liabilities	12 Months Ended
	Dec. 31, 2017
Finance Lease Liabilities [Abstract]
Finance Lease Liabilities	24. Finance Lease Liabilities (1) Lease contracts The Company enters into power purchase agreements (“PPA”) with GS EPS and three other providers. The Company recognizes these PPAs as finance leases; under the PPAs, there is no transfer of ownership or bargain purchase option of the plants at the end of the agreement, however, the present value of the future minimum power purchase payments equals substantially all of the plants’ respective fair values over a twenty-year period which makes up the major part of the respective plants’ economic life. (2) Finance lease liabilities as of December 31, 2016 and 2017 are as follows and are included in current and non-current 2016 2017 Minimum lease Present value of Minimum lease Present value of In millions of won Less than 1 year ￦ 175,512 121,176 174,534 131,792 1 ~ 5 years 404,029 306,282 272,994 204,069 More than 5 years 152,247 113,721 108,748 82,399 ￦ 731,788 541,179 556,276 418,260 (3) Current and non-current 2016 2017 In millions of won Current finance lease liabilities ￦ 121,176 131,792 Non-current 420,003 286,468 ￦ 541,179 418,260 (4) Minimum lease payment and contingent rent payment recognized as an expense as a lessee for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Minimum lease payment ￦ 177,585 158,859 Contingent rent payment (20,956 ) (21,024 ) (5) The Company does not have any irrevocable operating lease contracts as of December 31, 2016 and 2017. (6) Changes in finance lease liabilities for the year ended December 31, 2017 are as follows: Beginning balance Cash flow Ending balance In millions of won ￦541,179 (122,919) 418,260

Employment Benefits

Employment Benefits	12 Months Ended
	Dec. 31, 2017
Employment Benefits [Abstract]
Employment Benefits	25. Employment Benefits (1) Employment benefit obligations as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Net defined benefit obligations ￦ 1,678,470 1,476,201 Other long-term employee benefit obligations 7,788 6,868 ￦ 1,686,258 1,483,069 (2) Principal assumptions on actuarial valuation as of December 31, 2016 and 2017 are as follows: 2016 2017 Discount rate 2.45%~2.64% 2.75%~2.90% Future salary and benefit levels 5.23% 4.88% Weighted average duration 13.34 years 13.40 years (3) Details of expense relating to defined benefit plans for the years ended December 31, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Current service cost ￦ 315,811 378,930 392,820 Interest cost 63,808 67,104 79,524 Expected return on plan assets (22,557 ) (23,612 ) (31,307 ) Loss from settlement (641 ) (706 ) (1,055 ) ￦ 356,421 421,716 439,982 Expenses as described above are recognized in those items below in the financial statements. 2015 2016 2017 In millions of won Cost of sales ￦ 262,760 312,391 332,249 Selling and administrative expenses 51,932 61,362 59,111 Others (Construction-in-progress 41,729 47,963 48,622 ￦ 356,421 421,716 439,982 In addition, for the years ended December 31, 2015, 2016 and 2017, employee benefit obligations expenses of ￦57,940 million, ￦62,435 million and ￦65,603 million, respectively, are recognized as cost of sales, and ￦9,971 million, ￦11,450 million and ￦11,983 million, respectively, are recognized as selling and administrative expenses, and ￦14,195 million, ￦14,024 million and ￦13,332 million, respectively, are recognized as construction-in-progress (4) Details of defined benefit obligations as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Present value of defined benefit obligation from funded plans ￦ 2,867,377 2,951,842 Fair value of plan assets (1,188,907 ) (1,475,641 ) 1,678,470 1,476,201 Present value of defined benefit obligation from unfunded plans — — Net liabilities incurred from defined benefit plans ￦ 1,678,470 1,476,201 (5) Changes in the present value of defined benefit obligations for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ 2,426,414 2,867,377 Current service cost 378,930 392,820 Interest cost(*) 67,104 79,524 Remeasurement component 120,993 (258,223 ) Loss from settlement (707 ) (1,055 ) Actual payments (125,233 ) (128,707 ) Others (124 ) 106 Ending balance ￦ 2,867,377 2,951,842 (*) Corporate bond (AAA rated) yield at year-end (6) Changes in the fair value of plan assets for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ 930,632 1,188,907 Expected return 23,612 31,307 Remeasurement component (5,706 ) (10,435 ) Contributions by the employers 312,125 325,080 Actual payments (71,756 ) (59,218 ) Ending balance ￦ 1,188,907 1,475,641 In addition, loss on accumulated remeasurement component amounting to ￦222,997 million and ￦43,513 million has been recognized as other comprehensive income or loss for the years ended December 31, 2016 and 2017, respectively. (7) Details of the fair value of plan assets as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Equity instruments ￦ 86,054 79,204 Debt instruments 383,654 517,040 Bank deposit 305,670 293,477 Others 413,529 585,920 ￦ 1,188,907 1,475,641 For the years ended December 31, 2016 and 2017, actual returns on plan assets amounted to ￦17,906 million and ￦20,872 million, respectively. (8) Remeasurement component recognized in other comprehensive income (loss) for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Actuarial gain from changes in financial assumptions ￦ (27,792 ) (300,058 ) Experience adjustments 148,785 41,835 Expected return 5,706 10,435 ￦ 126,699 (247,788 ) Remeasurement component recognized as other comprehensive income or loss is recorded in retained earnings.

Provisions

Provisions	12 Months Ended
	Dec. 31, 2017
Provisions [Abstract]
Provisions	26. Provisions (1) Provisions as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Employment benefits Provisions for employment benefits ￦ 810,607 — 913,787 — Litigation Litigation provisions 79,359 118,878 48,621 24,955 Decommissioning cost Nuclear plants — 10,195,928 — 13,007,228 Spent fuel — 1,374,225 — 1,339,046 Waste 2,566 1,476,936 11,494 1,626,877 PCBs — 191,744 — 180,087 Other recovery provisions — 507 — 6,659 Others Power plant regional support program 152,851 — 153,756 — Transmission regional support program 282,608 — 243,365 — Provisions for tax 106 136 61 — Provisions for financial guarantee 458 29,207 — 23,475 Provisions for RPS 417,404 — 271,624 — Provisions for greenhouse gas emissions obligations 249,644 — 414,252 — Others 4,385 39,590 80,538 16,387 ￦ 1,999,988 13,427,151 2,137,498 16,224,714 (2) Changes in provisions for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Increase in Payment Reversal Others Ending balance In millions of won Employment benefits Provisions for employment benefits ￦ 718,365 1,047,342 (947,982 ) (7,108 ) (10 ) 810,607 Litigation Litigation provisions 167,965 124,931 (294,403 ) (20,736 ) 220,480 198,237 Decommissioning cost Nuclear plants 9,684,286 513,383 (1,741 ) — — 10,195,928 Spent fuel 1,375,185 469,982 (470,942 ) — — 1,374,225 Waste 1,502,140 49,092 (71,998 ) — 268 1,479,502 PCBs 182,400 30,675 (21,331 ) — — 191,744 Other recovery provisions 862 — — (20 ) (335 ) 507 Others Power plant regional support program 129,655 50,252 (41,540 ) — 14,484 152,851 Transmission regional support program 228,785 253,664 (199,841 ) — — 282,608 Provisions for tax 136 125 — — (19 ) 242 Provisions for financial guarantee 4,288 29,741 — (4,298 ) (66 ) 29,665 Provisions for RPS 363,178 420,154 (309,975 ) (55,953 ) — 417,404 Provisions for greenhouse gas emissions obligations 78,829 298,618 (116,336 ) (11,467 ) — 249,644 Others 7,856 37,491 (2,699 ) (9 ) 1,336 43,975 ￦ 14,443,930 3,325,450 (2,478,788 ) (99,591 ) 236,138 15,427,139 2017 Beginning Increase in Payment Reversal Others Ending balance In millions of won Employment benefits Provisions for employment benefits ￦ 810,607 984,896 (880,255 ) (1,461 ) — 913,787 Litigation Litigation provisions 198,237 34,629 (152,461 ) (7,096 ) 267 73,576 Decommissioning cost Nuclear plants 10,195,928 2,818,033 (6,733 ) — — 13,007,228 Spent fuel 1,374,225 307,682 (342,861 ) — — 1,339,046 Waste 1,479,502 222,632 (63,763 ) — — 1,638,371 PCBs 191,744 5,309 (14,266 ) (2,700 ) — 180,087 Other recovery provisions 507 5,939 — — 213 6,659 Others Power plant regional support program 152,851 94,039 (103,889 ) — 10,755 153,756 Transmission regional support program 282,608 143,178 (182,421 ) — — 243,365 Provisions for tax 242 — (25 ) (136 ) (20 ) 61 Provisions for financial guarantee 29,665 3,760 — (9,945 ) (5 ) 23,475 Provisions for RPS 417,404 242,946 (388,726 ) — — 271,624 Provisions for greenhouse gas emissions obligations 249,644 422,666 (256,758 ) (1,300 ) — 414,252 Others(*) 43,975 6,639 (3,348 ) (26,477 ) 76,136 96,925 ￦ 15,427,139 5,292,348 (2,395,506 ) (49,115 ) 87,346 18,362,212 (*) As described in note 50.(1), the Company believes that the possibility of economic outflow is probable on the cost of construction suspension of Shin-Kori Unit 5 and 6 for three months. For this reason, the Company recognized ￦77,261 million of provision as addition to construction-in-progress.

Government Grants

Government Grants	12 Months Ended
	Dec. 31, 2017
Government grants [Abstract]
Government Grants	27. Government Grants (1) Government grants as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Land ￦ (3,204 ) (21,968 ) Buildings (61,188 ) (63,539 ) Structures (197,641 ) (196,414 ) Machinery (111,064 ) (183,188 ) Vehicles (107 ) (6,322 ) Equipment (732 ) (761 ) Tools (430 ) (1,027 ) Construction-in-progress (135,807 ) (49,084 ) Finance lease assets — (27 ) Investment properties (64 ) (83 ) Software (595 ) (486 ) Development expenditures (5,152 ) (3,702 ) Intangible assets under development (11,090 ) (10,540 ) Usage rights of donated assets and other (21 ) (11 ) Other intangible assets other than goodwill — — ￦ (527,095 ) (537,152 ) (2) Changes in government grants for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Receipt Acquisition Offset the Disposal Others Ending In millions of won Cash ￦ — (32,878 ) — — — 32,878 — Land (3,147 ) — — — 14 (71 ) (3,204 ) Buildings (63,932 ) — — 5,299 731 (3,286 ) (61,188 ) Structures (193,119 ) — — 9,491 2,597 (16,610 ) (197,641 ) Machinery (108,935 ) — — 12,272 1,210 (15,611 ) (111,064 ) Vehicles (29 ) — — 25 — (103 ) (107 ) Equipment (1,026 ) — — 452 — (158 ) (732 ) Tools (691 ) — — 295 — (34 ) (430 ) Construction-in-progress (139,898 ) — 32,525 — — (28,434 ) (135,807 ) Investment properties (13 ) — — 1 — (52 ) (64 ) Software (699 ) — — 249 — (145 ) (595 ) Development expenditures (6,835 ) — — 2,771 — (1,088 ) (5,152 ) Intangible assets under development (10,483 ) — 991 — — (1,598 ) (11,090 ) Usage rights of donated assets and other (32 ) — — 11 — — (21 ) Others (1 ) — — 1 — — — ￦ (528,840 ) (32,878 ) 33,516 30,867 4,552 (34,312 ) (527,095 ) 2017 Beginning Receipt Acquisition Offset the Disposal Others Ending In millions of won Cash ￦ — (55,533 ) — — — 55,533 — Land (3,204 ) — — — 5 (18,769 ) (21,968 ) Buildings (61,188 ) — — 5,996 28 (8,375 ) (63,539 ) Structures (197,641 ) — — 10,011 1,905 (10,689 ) (196,414 ) Machinery (111,064 ) — — 17,390 489 (90,003 ) (183,188 ) Vehicles (107 ) — — 1,070 14 (7,299 ) (6,322 ) Equipment (732 ) — — 454 — (483 ) (761 ) Tools (430 ) — — 354 — (951 ) (1,027 ) Construction-in-progress (135,807 ) — 129,451 — — (42,728 ) (49,084 ) Finance lease assets — — — 1 — (28 ) (27 ) Investment properties (64 ) — — 2 — (21 ) (83 ) Software (595 ) — — 255 — (146 ) (486 ) Development expenditures (5,152 ) — — 2,811 — (1,361 ) (3,702 ) Intangible assets under development (11,090 ) — — — — 550 (10,540 ) Usage rights of donated assets and other (21 ) — — 10 — — (11 ) Others — — — — — — — ￦ (527,095 ) (55,533 ) 129,451 38,354 2,441 (124,770 ) (537,152 )

Deferred Revenues

Deferred Revenues	12 Months Ended
	Dec. 31, 2017
Deferred Revenues [Abstract]
Deferred Revenues	28. Deferred Revenues Deferred revenue related to the Company’s construction contracts for the years ended December 31, 2016 and 2017 are as follows which included in current and non-current non-financial 2016 2017 In millions of won Beginning balance ￦ 7,165,297 7,825,765 Increase during the current year / period 1,087,765 978,389 Recognized as revenue during the current year / period (427,297 ) (478,973 ) Ending balance ￦ 7,825,765 8,325,181

Non-financial Liabilities

Non-financial Liabilities	12 Months Ended
	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Non-financial Liabilities	29. Non-financial Non-financial 2016 2017 Current Non-current Current Non-current In millions of won Advance received ￦ 4,498,739 148,404 3,772,713 181,612 Unearned revenue 26,084 41,936 41,593 19,718 Deferred revenue 445,018 7,380,747 476,631 7,848,550 Withholdings 263,263 10,781 164,370 10,529 Others 1,135,106 9,737 1,129,001 12,025 ￦ 6,368,210 7,591,605 5,584,308 8,072,434

Contributed Capital

Contributed Capital	12 Months Ended
	Dec. 31, 2017
Disclosure of classes of share capital [Abstract]
Contributed Capital	30. Contributed Capital (1) Details of shares issued as of December 31, 2016 and 2017 are as follows: 2016 Shares authorized Shares issued Par value per share Owned by Owned by Total In millions of won except share information Common shares 1,200,000,000 641,964,077 ￦ 5,000 1,640,385 1,569,435 3,209,820 (*) Korea Development Bank’s ownership of ￦1,056,176 million is included. 2017 Shares authorized Shares issued Par value per share Owned by Owned by Total In millions of won except share information Common shares 1,200,000,000 641,964,077 ￦ 5,000 1,640,385 1,569,435 3,209,820 (*) Korea Development Bank’s ownership of ￦1,056,176 million is included. (2) Details in number of outstanding capital stock for the years ended December 31, 2016 and 2017 are as follows. 2016 2017 Number of shares Beginning balance 641,964,077 641,964,077 Ending balance 641,964,077 641,964,077 (3) Details of share premium as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Share premium ￦ 843,758 843,758

Retained Earnings and Dividends

Retained Earnings and Dividends Paid	12 Months Ended
	Dec. 31, 2017
Disclosure of Retained Earnings and Dividends Paid [Abstract]
Retained Earnings and Dividends Paid	31. Retained Earnings and Dividends Paid (1) Details of retained earnings as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Legal reserve(*) ￦ 1,604,910 1,604,910 Voluntary reserves 31,847,275 34,833,844 Retained earnings before appropriations 19,721,686 16,931,804 Retained earnings ￦ 53,173,871 53,370,558 (*) The KEPCO Act requires KEPCO to appropriate a legal reserve equal to at least 20 percent of net income for each accounting period until the reserve equals 50 percent of KEPCO’s common stock. The legal reserve is not available for cash dividends; however, this reserve may be credited to paid-in (2) Details of voluntary reserves as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Reserve for investment on social overhead capital ￦ 5,277,449 5,277,449 Reserve for research and human development(*) 330,000 330,000 Reserve for business expansion 26,029,826 29,016,395 Reserve for equalizing dividends 210,000 210,000 ￦ 31,847,275 34,833,844 (*) The reserve for research and human development is appropriated by KEPCO to use as qualified tax credits to reduce corporate tax liabilities. The reserve is available for cash dividends for a certain period as defined by the Restriction of Special Taxation Act of Korea. (3) Changes in retained earnings for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ 48,187,241 53,173,871 Net profit for the period attributed to owner of the Company 7,048,581 1,298,720 Changes in equity method retained earnings (2,532 ) 10,065 Remeasurements of defined benefit liability, net of tax (69,330 ) 158,991 Dividend paid (1,990,089 ) (1,271,089 ) Ending balance ￦ 53,173,871 53,370,558 (4) Dividends paid for the years ended December 31, 2016 and 2017 are as follows: 2015 In millions of won Number of shares issued Number of treasury stocks Number of shares eligible for dividends Dividends paid per share Dividends paid (In won) Common shares 641,964,077 — 641,964,077 ￦ 500 320,982 2016 In millions of won Number of shares issued Number of treasury stocks Number of shares eligible for dividends Dividends paid per share Dividends paid (In won) Common shares 641,964,077 — 641,964,077 ￦ 3,100 1,990,089 2017 In millions of won Number of shares issued Number of treasury stocks Number of shares eligible for dividends Dividends paid per share Dividends paid (In won) Common shares 641,964,077 — 641,964,077 ￦ 1,980 1,271,089 (5) Changes in retained earnings of investments in associates and joint ventures for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ (2,411 ) (4,943 ) Changes (2,532 ) 10,065 Ending balance ￦ (4,943 ) 5,122 (6) Changes in remeasurement components for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ (202,878 ) (222,997 ) Changes (119,316 ) 239,636 Income tax effect 49,986 (80,645 ) Transfer to reserve for business expansion 49,211 20,493 Ending balance ￦ (222,997 ) (43,513 )

Statement of Appropriation of R

Statement of Appropriation of Retained Earnings	12 Months Ended
	Dec. 31, 2017
Statement of Appropriation of Retained Earnings [Abstract]
Statement of Appropriation of Retained Earnings	32. Statement of Appropriation of Retained Earnings For the year ended December 31, 2016, KEPCO’s retained earnings were appropriated on March 21, 2017. For the year ended December 31, 2017, KEPCO’s retained earnings were appropriated on March 30, 2018. Statements of appropriation of retained earnings of KEPCO, the controlling company, for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won except for I.   Retained earnings before appropriations Unappropriated retained earnings carried over from prior years ￦ — — Net income 4,261,986 1,506,852 Remeasurements of the defined benefit plan (4,328 ) 72,723 4,257,658 1,579,575 II. Transfer from voluntary reserves — — III.  Subtotal (I+II) 4,257,658 1,579,575 IV.  Appropriations of retained earnings (4,257,658 ) (1,579,575 ) Legal reserve — — Dividends (government, individual) Amount of dividends per share (%) : Current year—￦ 790 (16%) Prior year—￦ 1,980 (40%) (1,271,089 ) (507,152 ) Reserve for business expansion (2,986,569 ) (1,072,423 ) V. Unappropriated retained earnings to be carried over forward to subsequent year — —

Hybrid Bonds

Hybrid Bonds	12 Months Ended
	Dec. 31, 2017
Hybrid Bonds [Abstract]
Hybrid Bonds	33. Hybrid Bonds Hybrid bonds classified as equity (non-controlling Issuer Hybrid bond Issued date Maturity Yield (%) 2016 2017 In millions of won Korea Western Power Co., Ltd. 1st hybrid bond 2012.10.18 — — ￦ 100,000 — Korea South-East Power Co., Ltd. 1st hybrid bond 2012.12.07 2042.12.06 4.38 170,000 170,000 Korea South-East Power Co., Ltd. 2nd hybrid bond 2012.12.07 2042.12.06 4.44 230,000 230,000 Expense of issuance (1,340 ) (1,090 ) ￦ 498,660 398,910 Although these instruments have contractual maturity dates, the contractual agreements allow these subsidiaries to indefinitely extend the maturity dates and defer the payment of interest without modification to the other terms of the instruments. When the Company decides not to pay dividends on ordinary shares, they are not required to pay interest on the hybrid bonds. Substantially, as these instruments have no contractual obligation to pay principal and interest, these instruments have been classified as equity (non-controlling Korea Western Power Co., Ltd., a subsidiary of the Company, repaid all of its hybrid bond classified as equity (non-controlling

Other Components of Equity

Other Components of Equity	12 Months Ended
	Dec. 31, 2017
Other Components of Equity [Abstract]
Other Components of Equity	34. Other Components of Equity (1) Other components of equity of the parent as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Other capital surplus ￦ 1,235,146 1,233,793 Accumulated other comprehensive loss (33,875 ) (271,457 ) Other equity 13,294,973 13,294,973 ￦ 14,496,244 14,257,309 (2) Changes in other capital surplus for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 Gains on Treasury stocks Others Subtotal Gains on disposal of treasury stocks Others Subtotal In millions of won Beginning balance ￦ 387,524 809,864 1,197,388 387,524 847,622 1,235,146 Disposal of subsidiary — 36,008 36,008 — — — Issuance of share capital of subsidiary — 1,750 1,750 — (1,378 ) (1,378 ) Others — — — — 25 25 Ending balance ￦ 387,524 847,622 1,235,146 387,524 846,269 1,233,793 (3) Changes in accumulated other comprehensive income (loss) for the years ended December 31, 2016 and 2017 are as follows: 2016 Available-for-sale financial asset valuation reserve Shares in other Income (loss) of investments in associates and Reserve for overseas translation credit Reserve for derivatives Total In millions of won Beginning balance ￦ (24,905 ) 276,373 (254,462 ) (95,719 ) (98,713 ) Changes in the unrealized fair value of available-for-sale 61,275 — — — 61,275 Shares in other comprehensive loss of associates and joint ventures, net of tax — (54,918 ) — — (54,918 ) Foreign currency translation of foreign operations, net of tax — — 31,406 — 31,406 Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax — — — 27,075 27,075 Ending balance ￦ 36,370 221,455 (223,056 ) (68,644 ) (33,875 ) 2017 Available-for-sale financial asset valuation reserve Shares in other Income (loss) of investments in associates and Reserve for overseas translation credit Reserve for gain (loss) on derivatives Total In millions of won Beginning balance ￦ 36,370 221,455 (223,056 ) (68,644 ) (33,875 ) Changes in the unrealized fair value of available-for-sale (7,102 ) — — — (7,102 ) Shares in other comprehensive loss of associates and joint ventures, net of tax — (154,991 ) — — (154,991 ) Foreign currency translation of foreign operations, net of tax — — (95,103 ) — (95,103 ) Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax — — — 19,614 19,614 Ending balance ￦ 29,268 66,464 (318,159 ) (49,030 ) (271,457 ) (4) Details of changes in other equity for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Statutory revaluation reserve ￦ 13,295,098 13,295,098 Changes in other equity (125 ) (125 ) ￦ 13,294,973 13,294,973

Sales

Sales	12 Months Ended
	Dec. 31, 2017
Revenue [Abstract]
Sales	35. Sales Details of sales for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 Domestic Overseas Domestic Overseas Domestic Overseas In millions of won Sales of goods ￦ 53,961,463 405,573 54,982,095 397,392 55,373,316 399,232 Electricity 53,229,470 — 54,304,529 — 54,649,882 — Heat supply 204,987 — 181,597 — 205,838 — Others 527,006 405,573 495,969 397,392 517,596 399,232 Sales of service 209,189 244,298 195,697 161,046 186,990 164,167 Sales of construction services 180,424 3,580,780 132,219 3,894,638 92,501 3,119,683 ￦ 54,351,076 4,230,651 55,310,011 4,453,076 55,652,807 3,683,082

Selling and Administrative Expe

Selling and Administrative Expenses	12 Months Ended
	Dec. 31, 2017
Selling, general and administrative expense [Abstract]
Selling and Administrative Expenses	36. Selling and Administrative Expenses (1) Selling and administrative expenses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Salaries ￦ 655,432 734,930 735,383 Retirement benefit expense 61,903 72,812 71,094 Welfare and benefit expense 119,866 162,243 179,406 Insurance expense 10,636 11,513 15,414 Depreciation 102,867 169,431 190,245 Amortization of intangible assets 40,465 35,171 44,990 Bad debt expense 290 38,719 126,714 Commission 562,171 605,879 673,740 Advertising expense 30,085 34,658 114,519 Training expense 4,988 6,314 7,027 Vehicle maintenance expense 10,529 10,390 9,998 Publishing expense 3,124 3,643 3,672 Business promotion expense 3,338 3,477 3,700 Rent expense 44,905 40,020 38,380 Telecommunication expense 22,678 25,448 24,916 Transportation expense 753 596 495 Taxes and dues 55,970 46,531 48,395 Expendable supplies expense 7,272 6,834 7,731 Water, light and heating expense 9,558 9,720 10,545 Repairs and maintenance expense 74,330 75,122 63,477 Ordinary development expense 178,472 188,063 211,417 Travel expense 14,388 16,115 16,658 Clothing expense 5,751 8,273 8,410 Survey and analysis expense 590 666 698 Membership fee 1,040 1,132 1,122 Others 131,860 331,532 154,709 ￦ 2,153,261 2,639,232 2,762,855 (2) Other selling and administrative expenses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Accommodation development expenses ￦ 28,134 186,896 55,799 Miscellaneous wages 43,109 31,907 32,300 Litigation and filing expenses 10,670 12,328 11,881 Compensation for damages 9,032 60,341 12,297 Outsourcing expenses 2,865 3,530 2,647 Reward expenses 2,472 3,267 2,786 Overseas market development expenses 1,541 2,177 1,876 Others 34,037 31,086 35,123 ￦ 131,860 331,532 154,709

Other Income and Expense

Other Income and Expense	12 Months Ended
	Dec. 31, 2017
Disclosure of other operating income (expense) [Abstract]
Other Income and Expense	37. Other Income and Expense (1) Other income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Reversal of other provisions ￦ 6,355 22,034 35,265 Reversal of other allowance for doubtful accounts 413 5,489 2,166 Gains on government grants 204 111 430 Gains on assets contributed 9,004 12,254 4,218 Gains on liabilities exempted 2,588 1,959 3,166 Compensation and reparations revenue 166,355 114,530 89,196 Revenue from research contracts 5,342 13,143 12,580 Income related to transfer of assets from customers 375,995 427,297 478,973 Rental income 196,406 211,580 192,136 Others 45,552 31,787 50,988 ￦ 808,214 840,184 869,118 (2) Details of others of other income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Refund of claim for rectification ￦ 7,623 8,722 9,655 Adjustment of research project 4,090 4,148 3,884 Maintenance expenses on lease building 324 354 135 Training expenses 4,774 4,478 3,045 Deposit redemption 430 991 34 Reversal of expenses on litigation 219 893 360 Revenue on royalty fee 2,739 2,486 2,888 Reimbursement of insurance fee 11,797 — 1,498 Gains on guarantee contracts 4,523 2,796 456 Others 9,033 6,919 29,033 ￦ 45,552 31,787 50,988 (3) Other expense for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Compensation and indemnification expense ￦ 16,959 — 37 Accretion expenses of other provisions 4,575 4,556 7,535 Depreciation expenses on investment properties 669 678 1,176 Depreciation expenses on idle assets 6,698 6,639 6,644 Other bad debt expense 18,473 4,585 1,778 Donations 34,134 114,094 119,421 Others 27,340 58,072 43,464 ￦ 108,848 188,624 180,055 (4) Details of others of other expense for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Operating expenses related to the idle assets ￦ 779 459 136 Research grants 1,392 1,461 1,180 Supporting expenses on farming and fishing village 14,626 15,201 11,956 Operating expenses on fitness center 2,912 2,706 3,498 Expenses on adjustment of research and development grants 709 — 806 Taxes and dues 1,105 4,582 2,270 Expenses on R&D supporting 146 690 5,459 Moving expense 3,191 — — Others 2,480 32,973 18,159 ￦ 27,340 58,072 43,464

Other Gains (Losses)

Other Gains (Losses)	12 Months Ended
	Dec. 31, 2017
Other Gains (Losses) [Abstract]
Other Gains (Losses)	38. Other Gains (Losses) (1) Composition of other gains (losses) for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Other gains Gains on disposal of property, plant, and equipment ￦ 8,637,508 74,035 48,316 Gains on disposal of intangible assets 32 — 564 Reversal of impairment loss on intangible assets 275 3 54 Gains on foreign currency translation 13,784 15,311 20,485 Gains on foreign currency transaction 61,007 55,377 93,151 Gains on insurance proceeds 30 — 400 Others 162,128 187,792 269,562 Other losses Losses on disposal of property, plant and equipment (73,073 ) (42,715 ) (70,514 ) Losses on disposal of intangible assets (16 ) (158 ) (183 ) Impairment loss on property, plant and equipment (30,344 ) — (51,067 ) Impairment loss on intangible assets (22 ) (3,945 ) (20 ) Losses on foreign currency translation (15,097 ) (23,835 ) (25,495 ) Losses on foreign currency transaction (75,615 ) (72,058 ) (36,241 ) Others (69,824 ) (119,309 ) (92,385 ) ￦ 8,610,773 70,498 156,627 (2) Details of others of other gains for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Gains on disposal of inventories ￦ 10,758 9,494 6,024 Gains on valuation of inventories 7 2 — Gains on proxy collection of TV license fee 38,529 38,991 39,711 Gains on compensation of impaired electric poles — 3,650 1,526 Gains on compensation for infringement on contract 7,414 3,040 18,990 Gains on harbor facilities dues 5,943 2,957 3,025 Gains on technical fees 1,258 1,271 2,105 Reversal of occupation development training fees 1,878 1,756 1,697 Gains on disposal of waste 2,880 4,222 4,261 Gains on insurance 11,865 3,786 10,410 Gains on litigation 600 — — Gains on tax rebate 1,661 5,226 2,161 Gains on other commission 2,177 4,639 4,790 Gains on research tasks 1,446 10 — Gains on settlement and others 2,803 2,188 — Gains on sales of greenhouse gas emissions rights 52 46 — Others 72,857 106,514 174,862 ￦ 162,128 187,792 269,562 (3) Details of others of other losses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Losses on valuation of inventories ￦ 1,318 2,683 3,875 Losses on disposal of inventories 13,469 3,092 3,273 Losses due to disaster 263 1,522 5,374 Losses on rounding adjustment of electric charge surtax 1,251 1,260 1,253 Losses on adjustments of levies 13,928 1,184 1 Forfeit of taxes and dues 190 4,582 656 Losses on litigation 488 2,581 — Others 38,917 102,405 77,953 ￦ 69,824 119,309 92,385

Finance Income

Finance Income	12 Months Ended
	Dec. 31, 2017
Finance income [Abstract]
Finance Income	39. Finance Income (1) Finance income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Interest income ￦ 241,585 241,778 206,143 Dividends income 14,069 9,446 11,477 Gains on disposal of financial assets 4 1,482 1,130 Gains on valuation of Financial assets at fair value through profit or loss — — 12 Gains on valuation of derivatives 610,582 293,830 16,165 Gains on transaction of derivatives 151,851 45,549 29,257 Gains on foreign currency translation 127,372 161,905 1,115,832 Gains on foreign currency transaction 37,377 37,553 150,602 Other finance income 148 — — ￦ 1,182,988 791,543 1,530,618 (2) Interest income included in finance income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Cash and cash equivalents ￦ 54,687 61,380 35,474 Available-for-sale 29 — 290 Held-to-maturity 99 97 82 Loans and receivables 28,586 25,106 30,014 Short-term financial instrument 46,921 45,763 29,412 Long-term financial instrument 10,492 7,195 8,144 Trade and other receivables 100,771 102,237 102,727 ￦ 241,585 241,778 206,143

Finance Expenses

Finance Expenses	12 Months Ended
	Dec. 31, 2017
Finance Expenses [Abstract]
Finance Expenses	40. Finance Expenses (1) Finance expenses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Interest expense ￦ 2,015,684 1,752,868 1,789,552 Losses on sale of financial assets 3,008 9 2,343 Impairment of available-for-sale 84,370 86,703 2,713 Losses on valuation of derivatives 17,051 5,762 890,832 Losses on transaction of derivatives 37,262 101,987 198,218 Losses on foreign currency translation 743,283 406,849 207,944 Losses on foreign currency transaction 113,723 57,889 35,175 Losses on repayment of financial liabilities 33 23,000 5 Other 1,043 2,020 1,170 ￦ 3,015,457 2,437,087 3,127,952 (2) Interest expense included in finance expenses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Trade and other payables ￦ 84,527 68,375 57,160 Short-term borrowings 14,627 6,969 35,891 Long-term borrowings 103,503 91,584 87,011 Debt securities 2,177,855 1,922,900 1,698,232 Other financial liabilities 538,680 482,428 491,665 2,919,192 2,572,256 2,369,959 Less: Capitalized borrowing costs ￦ (903,508 ) (819,388 ) (580,407 ) 2,015,684 1,752,868 1,789,552 Capitalization rates for the years ended December 31, 2015, 2016 and 2017 are 2.36%~4.25%, 2.29%~4.16% and 2.30%~3.60%, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income tax expense [Abstract]
Income Taxes	41. Income Taxes (1) Income tax expense for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Current income tax expense Payment of income tax ￦ 2,682,779 2,689,640 881,583 Adjustment due to changes in estimates related to prior years (23,248 ) 231,113 4,484 Current income tax directly recognized in equity 37,768 30,059 (56,098 ) 2,697,299 2,950,812 829,969 Deferred income tax expense Generation and realization of temporary differences 48,878 509,762 1,283,012 Changes of unrecognized tax losses, tax credit and temporary differences for prior periods 71,999 (86,845 ) 44,573 Changes in deferred tax on tax losses carryforwards 2,374,237 — — Tax credit carryforwards 47,000 (8,588 ) 15,270 2,542,114 414,329 1,342,855 Income tax expense ￦ 5,239,413 3,365,141 2,172,824 (2) Reconciliation between actual income tax expense and amount computed by applying the statutory tax rate to income before income taxes for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Income before income tax ￦ 18,655,786 10,513,468 3,614,218 Income tax expense computed at applicable tax rate of 24.2% 4,514,700 2,544,259 874,641 Adjustments Effect of applying gradual tax rate (4,147 ) (5,082 ) (5,082 ) Effect of non-taxable (8,047 ) (29,554 ) (32,032 ) Effect of non-deductible 17,734 22,258 15,032 Effects of tax credits and deduction (103,435 ) (194,731 ) (161,069 ) Recognition (reversal) of unrecognized deferred tax asset, net 71,999 (86,845 ) 44,573 Effect of change in deferred tax due to change in tax rate (from 24.2% to 27.5%) — — 1,055,154 Deferred income tax related to investments in subsidiaries and associates 784,793 862,956 394,145 Others, net (10,936 ) 20,767 (17,022 ) 747,961 589,769 1,293,699 Adjustment in respect of prior years due to change in estimate (23,248 ) 231,113 4,484 Income tax expense ￦ 5,239,413 3,365,141 2,172,824 Effective tax rate 28 % 32 % 60 % (3) Income tax directly adjusted to shareholders’ equity (except for accumulated other comprehensive income (loss)) for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Dividends of hybrid bond ￦ 5,253 5,253 5,248 Gain on disposal of investments in subsidiaries (14,144 ) (7,006 ) — Effect of change in effective tax rate — — (25 ) ￦ (8,891) (1,753 ) 5,223 (4) Income tax recognized as other comprehensive income (loss) for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Income tax recognized as other comprehensive income (loss) Loss on valuation of available-for-sale ￦ (6,315 ) (8,143 ) (2,551 ) Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax 7,253 (18,335 ) (11,016 ) Remeasurement of defined benefit obligations 42,913 49,986 (80,645 ) Investments in associates 13,648 7,731 8,649 Others (10,840 ) 573 24,242 ￦ 46,659 31,812 (61,321 ) (5) Changes in deferred income tax assets (liabilities) recognized in the statements of financial position for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning balance Amounts Amount Amounts recognized directly in equity Ending balance In millions of won Deferred income tax on temporary differences Employee benefits ￦ 407,342 36,003 49,986 — 493,331 Cash flow hedge (29,013 ) (6,235 ) (18,335 ) — (53,583 ) Investments in associates or subsidiaries (6,449,998 ) (717,072 ) 7,731 (7,006 ) (7,166,345 ) Property, plant and equipment (5,495,786 ) (31,532 ) — — (5,527,318 ) Finance lease (272,430 ) (73,001 ) — — (345,431 ) Intangible assets 9,420 (433 ) — — 8,987 Financial assets at fair value through profit or loss (4 ) (58 ) — — (62 ) Available-for-sale (49,199 ) (11,005 ) (8,143 ) — (68,347 ) Deferred revenue 215,361 (1,502 ) — — 213,859 Provisions 3,372,423 210,948 — — 3,583,371 Doubtful receivables 1,405 1,291 — — 2,696 Other finance liabilities 26,298 (1,302 ) — 5,253 30,249 Gains or losses on foreign exchange translation 128,714 10,224 — — 138,938 Allowance for doubtful accounts 18,976 (1,724 ) — — 17,252 Accrued income (11,231 ) 5,864 — — (5,367 ) Special deduction for property, plant and equipment (194,347 ) 38 — — (194,309 ) Reserve for research and human development (20,688 ) 7,805 — — (12,883 ) Others 576,585 118,712 573 — 695,870 (7,766,172 ) (452,979 ) 31,812 (1,753 ) (8,189,092 ) Deferred income tax on unused tax losses and tax credit Tax losses (3 ) 3 — — — Tax credit 27,115 8,588 — — 35,703 27,112 8,591 — — 35,703 ￦ (7,739,060 ) (444,388 ) 31,812 (1,753 ) (8,153,389 ) 2017 Beginning balance Amounts Amount Amounts recognized directly in equity Ending balance In millions of won Deferred income tax on temporary differences Employee benefits ￦ 493,331 86,008 (80,645 ) — 498,694 Cash flow hedge (53,583 ) 130,044 (11,016 ) — 65,445 Investments in associates or subsidiaries (7,166,345 ) (1,510,295 ) 8,649 (25 ) (8,668,016 ) Property, plant and equipment (5,527,318 ) (1,333,122 ) — — (6,860,440 ) Finance lease (345,431 ) (81,518 ) — — (426,949 ) Intangible assets 8,987 (1,339 ) — — 7,648 Financial assets at fair value through profit or loss (62 ) 952 — — 890 Available-for-sale (68,347 ) 62,055 (2,551 ) — (8,843 ) Deferred revenue 213,859 16,852 — — 230,711 Provisions 3,583,371 1,239,462 — — 4,822,833 Doubtful receivables 2,696 (2,637 ) — — 59 Other finance liabilities 30,249 (2,742 ) — 5,248 32,755 Gains or losses on foreign exchange translation 138,938 (140,292 ) — — (1,354 ) Allowance for doubtful accounts 17,252 25,679 — — 42,931 Accrued income (5,367 ) 3,542 — — (1,825 ) Special deduction for property, plant and equipment (194,309 ) (6,618 ) — — (200,927 ) Reserve for research and human development (12,883 ) 9,842 — — (3,041 ) Others 695,870 232,642 24,242 — 952,754 (8,189,092 ) (1,271,485 ) (61,321 ) 5,223 (9,516,675 ) Deferred income tax on unused tax losses and tax credit Tax losses — — — — — Tax credit 35,703 (15,272 ) — — 20,431 35,703 (15,272 ) — — 20,431 ￦ (8,153,389 ) (1,286,757 ) (61,321 ) 5,223 (9,496,244 ) (6) Deferred income tax assets (liabilities) recognized in the statements of financial position as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Deferred income tax assets ￦ 795,131 919,153 Deferred income tax liabilities (8,948,520 ) (10,415,397 ) ￦ (8,153,389 ) (9,496,244 ) (7) Details of deductible temporary differences, tax losses and unused tax credits for which no deferred income tax assets were recognized as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Deductible temporary differences ￦ 426,718 444,426

Assets Held-for-Sale

Assets Held-for-Sale	12 Months Ended
	Dec. 31, 2017
Assets Held-for-Sale [Abstract]
Assets Held-for-Sale	42. Assets Held-for-Sale Assets held-for-sale 2016 2017 In millions of won Land(*1) ￦ 2,907 2,765 Building(*1) 20,366 19,369 Investments in associates(*2, 3, 4) 42,569 5,837 ￦ 65,842 27,971 (*1) The board of directors of KEPCO Engineering & Construction Company, Inc., a subsidiary of the Company, determined to dispose the office building in Yongin as part of the government’s plan to relocate state-run held-for-sale. (*2) Korea Western Power Co., Ltd., a subsidiary of the Company, planned to dispose certain portion of its investment in Dongducheon Dream Power Co., Ltd. and had classified the relevant book value as non-current held-for-sale. (*3) Korea Hydro & Nuclear Power Co., Ltd., a subsidiary of the Company, initiated efforts to sell its shares in Yeongwol Energy Station Co., Ltd. during the year ended December 31, 2016. KHNP won the first trial of the lawsuit against the counterparty on November 2, 2017. However, the planned sale period has been extended since the appeal is ongoing as of December 31, 2017. The Company expects the sale to occur in 2018. (*4) KEPCO Engineering & Construction Company, Inc., a subsidiary of the Company, exercised a put option to sell the shares of DS POWER Co., Ltd. on December 11, 2017 and the shares are expected to be sold on February 28, 2018. Thus, the Company reclassified the relevant book value to assets held-for-sale.

Expenses Classified by Nature

Expenses Classified by Nature	12 Months Ended
	Dec. 31, 2017
Expenses Classified by Nature [Abstract]
Expenses Classified by Nature	43. Expenses Classified by Nature Expenses classified by nature for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 Selling and Cost of sales Total In millions of won Raw materials used ￦ — 14,626,933 14,626,933 Salaries 655,432 2,962,476 3,617,908 Retirement benefit expense 61,903 320,700 382,603 Welfare and benefit expense 119,866 426,186 546,052 Insurance expense 10,636 83,910 94,546 Depreciation 102,867 8,158,884 8,261,751 Amortization of intangible assets 40,465 31,801 72,266 Bad debt expense 290 — 290 Commission 562,171 353,703 915,874 Advertising expense 30,085 8,498 38,583 Training expense 4,988 11,186 16,174 Vehicle maintenance expense 10,529 8,323 18,852 Publishing expense 3,124 3,981 7,105 Business promotion expense 3,338 4,312 7,650 Rent expense 44,905 142,054 186,959 Telecommunication expense 22,678 73,180 95,858 Transportation expense 753 5,336 6,089 Taxes and dues 55,970 397,161 453,131 Expendable supplies expense 7,272 29,874 37,146 Water, light and heating expense 9,558 26,870 36,428 Repairs and maintenance expense 74,330 1,771,760 1,846,090 Ordinary development expense 178,472 432,748 611,220 Travel expense 14,388 52,910 67,298 Clothing expense 5,751 4,135 9,886 Survey and analysis expense 590 3,071 3,661 Membership fee 1,040 6,401 7,441 Power purchase — 11,428,027 11,428,027 Others 131,860 4,083,309 4,215,169 ￦ 2,153,261 45,457,729 47,610,990 2016 Selling and Cost of sales Total In millions of won Raw materials used ￦ — 13,470,586 13,470,586 Salaries 734,930 3,425,712 4,160,642 Retirement benefit expense 72,812 374,826 447,638 Welfare and benefit expense 162,243 507,691 669,934 Insurance expense 11,513 79,987 91,500 Depreciation 169,431 8,704,525 8,873,956 Amortization of intangible assets 35,171 44,544 79,715 Bad debt expense 38,719 — 38,719 Commission 605,879 423,179 1,029,058 Advertising expense 34,658 9,693 44,351 Training expense 6,314 13,347 19,661 Vehicle maintenance expense 10,390 7,016 17,406 Publishing expense 3,643 4,615 8,258 Business promotion expense 3,477 4,836 8,313 Rent expense 40,020 133,670 173,690 Telecommunication expense 25,448 75,925 101,373 Transportation expense 596 5,153 5,749 Taxes and dues 46,531 464,962 511,493 Expendable supplies expense 6,834 34,668 41,502 Water, light and heating expense 9,720 25,820 35,540 Repairs and maintenance expense 75,122 1,896,656 1,971,778 Ordinary development expense 188,063 517,441 705,504 Travel expense 16,115 63,611 79,726 Clothing expense 8,273 5,363 13,636 Survey and analysis expense 666 3,209 3,875 Membership fee 1,132 8,714 9,846 Power purchase — 10,755,739 10,755,739 Others 331,532 4,488,065 4,819,597 ￦ 2,639,232 45,549,553 48,188,785 2017 Selling and Cost of sales Total In millions of won Raw materials used ￦ — 15,924,707 15,924,707 Salaries 735,383 3,479,591 4,214,974 Retirement benefit expense 71,094 397,852 468,946 Welfare and benefit expense 179,406 543,738 723,144 Insurance expense 15,414 90,677 106,091 Depreciation 190,245 9,461,974 9,652,219 Amortization of intangible assets 44,990 68,682 113,672 Bad debt expense 126,714 — 126,714 Commission 673,740 469,695 1,143,435 Advertising expense 114,519 10,917 125,436 Training expense 7,027 14,362 21,389 Vehicle maintenance expense 9,998 7,468 17,466 Publishing expense 3,672 4,248 7,920 Business promotion expense 3,700 4,973 8,673 Rent expense 38,380 148,509 186,889 Telecommunication expense 24,916 73,956 98,872 Transportation expense 495 9,145 9,640 Taxes and dues 48,395 437,643 486,038 Expendable supplies expense 7,731 31,994 39,725 Water, light and heating expense 10,545 30,150 40,695 Repairs and maintenance expense 63,477 2,047,943 2,111,420 Ordinary development expense 211,417 510,020 721,437 Travel expense 16,658 69,015 85,673 Clothing expense 8,410 4,985 13,395 Survey and analysis expense 698 3,661 4,359 Membership fee 1,122 8,482 9,604 Power purchase — 14,264,331 14,264,331 Others 154,709 3,980,137 4,134,846 ￦ 2,762,855 52,098,855 54,861,710

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings per share [Abstract]
Earnings per share	44. Earnings Per Share (1) Basic earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In won Basic earnings per share ￦ 20,701 10,980 2,023 (2) Diluted earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In won Diluted earnings per share ￦ 20,701 10,980 2,023 (3) Basic earnings per share Net profit for the period and weighted average number of common shares used in the calculation of basic earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In millions of won except number of shares Net profit attributable to controlling interest ￦ 13,289,127 7,048,581 1,298,720 Profit used in the calculation of total basic earnings per share 13,289,127 7,048,581 1,298,720 Weighted average number of common shares 641,964,077 641,964,077 641,964,077 (4) Diluted earnings per share Diluted earnings per share is calculated by applying adjusted weighted average number of common shares under the assumption that all dilutive potential common shares are converted to common shares. Earnings used in the calculation of total diluted earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In millions of won Profit used in the calculation of total diluted earnings per share ￦ 13,289,127 7,048,581 1,298,720 Weighted average common shares used in calculating diluted earnings per share are adjusted from weighted average common shares used in calculating basic earnings per share. Detailed information of the adjustment for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In number of shares Weighted average number of common shares 641,964,077 641,964,077 641,964,077 Diluted weighted average number of shares 641,964,077 641,964,077 641,964,077 (5) There are no potential dilutive instruments and diluted earnings per share are same as basic earnings per share for the years ended December 31, 2015, 2016 and 2017.

Risk Management

Risk Management	12 Months Ended
	Dec. 31, 2017
Risk Management [Abstract]
Risk Management	45. Risk Management (1) Capital risk management The Company manages its capital to ensure that entities in the Company will be able to continue while maximizing the return to shareholder through the optimization of the debt and equity balance. The capital structure of the Company consists of net debt (offset by cash and cash equivalents) and equity. The Company’s overall capital risk management strategy remains unchanged from that of the prior year. Details of the Company’s capital management accounts as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Total borrowings and debt securities ￦ 53,639,205 54,747,392 Cash and cash equivalents 3,051,353 2,369,739 Net borrowings and debt securities 50,587,852 52,377,653 Total shareholder’s equity 73,050,545 72,964,641 Debt to equity ratio 69.25 % 71.78 % (2) Financial risk management The Company is exposed to various risks related to its financial instruments, such as, market risk (currency risk, interest rate risk, price risk), credit risk. The Company monitors and manages the financial risks relating to the operations of the Company through internal risk reports which analyze exposures by degree and magnitude of risks. The Company uses derivative financial instruments to hedge certain risk exposures. The Company’s overall financial risk management strategy remains unchanged from that of the prior year. (i) Credit risk Credit risk is the risk of finance loss to the Company if a customer or counterparty to a financial instrument fails to meet its contractual obligations, and arises primarily from the sales activities, securities and derivatives. In addition, credit risk exposure may exist within financial guarantees and unused line of credits. As these financial institutions the Company makes transactions with are reputable financial institutions, the credit risk from them are considered limited. The Company decides credit transaction limits based on evaluation of client’s credit, through information obtained from the credit bureau and disclosed financial position at committing contracts. ① Credit risk management Electricity sales, the main operations of the Company are the necessity for daily life and industrial activities of Korean nationals, and have importance as one of the national key industries. The Company dominates the domestic market supplying electricity to customers. The Company is not exposed to significant credit risk as customers of the Company are diverse and are from various industries and areas. The Company uses publicly available information and its own internal data related to trade receivables, to rate its major customers and to measure the credit risk that a counter party will default on a contractual obligation. For the incurred but not recognized loss, it is measured considering overdue period. ② Impairment and allowance account In accordance with the Company policies, individual material financial assets are assessed on a regular basis, trade receivables that are assessed not to be impaired individually are, in addition, assessed for impaiirment on a collective basis. Value of the acquired collateral (including the confirmation of feasibility) and estimated collectable amounts are included in this assessment. Allowance for bad debts assessed on a collective basis are recognized for (i) the Company of assets which individually are not material and (ii) incurred but not recognized losses that are assessed using statistical methods, judgment and past experience. Book values of the financial assets represent the maximum exposed amounts of the credit risk. Details of the Company’s level of maximum exposure to credit risk as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Cash and cash equivalents ￦ 3,051,353 2,369,739 Derivative assets (trading) 367,477 22,020 Available-for-sale 1,014,732 699,833 Held-to-maturity 3,244 3,144 Loans and receivables 834,207 905,641 Long-term/short-term financial instruments 2,695,926 2,244,514 Financial assets at fair value through profit or loss — 111,512 Derivative assets (using hedge accounting) 413,897 10,606 Trade and other receivables 9,692,391 9,683,769 Financial guarantee contracts(*) 1,396,152 1,154,862 (*) Maximum exposure associated with the financial guarantee contracts is the maximum amounts of the obligation. As of the reporting date, there are no financial assets and non-financial (ii) Market risk Market risk is the risk that the Company’s fair values of the financial instruments or future cash flows are affected by the changes in the market. Market risk consists of interest rate risk, currency risk and other price risk. (iii) Sensitivity analysis Significant assets and liabilities with uncertainties in underlying assumptions ① Defined benefit obligation A sensitivity analysis of defined benefit obligation assuming a 1% increase and decrease movements in the actuarial valuation assumptions as of December 31, 2016 and 2017 are as follows: 2016 2017 Type Accounts 1% Increase 1% Decrease 1% Increase 1% Decrease In millions of won Future salary increases Increase (decrease) in defined benefit obligation ￦ 344,874 (304,685 ) 354,852 (305,494 ) Discount rate Increase (decrease) in defined benefit obligation (305,031 ) 371,689 (313,597 ) 377,148 Changes of employee benefits assuming a 1% increase and decrease movements in discount rate on plan asset for the years ended December 31, 2016 and 2017 are ￦9,096 million and ￦11,875 million, respectively. ② Provisions Changes in provisions due to movements in underlying assumptions as of December 31, 2016 and 2017 are as follows: Type Accounts 2016 2017 PCBs Inflation rate 1.29 % 1.23 % Discount rate 2.77 % 2.55 % Nuclear plants Inflation rate 1.40 % 1.21 % Discount rate 3.55 % 2.94 % Spent fuel Inflation rate 2.93 % 2.93 % Discount rate 4.49 % 4.49 % A sensitivity analysis of provisions assuming a 0.1% increase and decrease movements in the underlying assumptions as of December 31, 2016 and 2017 are as follows: 2016 2017 Type Accounts 0.1% Increase 0.1% Decrease 0.1% Increase 0.1% Decrease In millions of won Discount rate PCBs ￦ (817 ) 822 (811 ) 816 Nuclear plants (209,277 ) 215,139 (262,949 ) 270,370 Spent fuel (52,353 ) 54,387 (51,015 ) 52,997 Inflation rate PCBs 834 (830 ) 826 (822 ) Nuclear plants 240,115 (233,553 ) 287,926 (280,249 ) Spent fuel 55,173 (53,182 ) 53,763 (51,823 ) Management judgment effected by uncertainties in underlying assumptions ① Foreign currency risk The Company undertakes transactions denominated in foreign currencies; consequently, exposures to exchange rate fluctuations arise. The carrying amounts of the Company’s foreign currency denominated monetary assets and monetary liabilities as of December 31, 2016 and 2017 are as follows: Assets Liabilities Type 2016 2017 2016 2017 In thousands of foreign currencies AED 7,479 5,693 1,534 2,049 AUD 187 145 632,613 652,259 BDT 49,110 60,208 833 1,001 BWP 4,296 797 3,222 — CAD — 82 — 171 CHF — — 400,308 400,004 CNY — 13,007 — 26,140 EUR 17,585 5,708 14,111 68,003 GBP 3 3 110 2,327 IDR 52,568 167,775 — — INR 1,059,092 1,228,259 161,631 227,078 JOD 1,746 1,624 5 5 JPY 520,746 799,501 20,442,504 21,624,128 KZT 12,157 359 — — MGA 3,408,579 2,762,572 150,430 319,581 NOK — — — 482 PHP 415,818 189,261 136,700 125,431 PKR 274,090 251,190 5,051 4,676 SAR 1,149 1,191 — 44 SEK — — — 449,002 USD 1,319,524 1,653,858 9,445,567 8,321,335 UYU 1,307 12,955 586 10,586 ZAR 386 361 75 4 A sensitivity analysis on the Company’s income for the period assuming a 10% increase and decrease in currency exchange rates as of December 31, 2016 and 2017 are as follows: 2016 2017 Type 10% Increase 10% Decrease 10% Increase 10% Decrease In millions of won Increase (decrease) of income before ￦ (1,101,372 ) 1,101,372 (844,122 ) 844,122 Increase (decrease) of shareholder’s (1,101,372 ) 1,101,372 (844,122 ) 844,122 (*) The effect on the shareholders’ equity excluding the impact of income taxes. The sensitivity analysis above is conducted for monetary assets and liabilities denominated in foreign currencies other than functional currency, without consideration of hedge effect of related derivatives, as of December 31, 2016 and 2017. To manage its foreign currency risk related to foreign currency denominated receivables and payables, the Company has a policy to enter into currency forward agreements. In addition, to manage its foreign currency risk related to foreign currency denominated expected sales transactions and purchase transactions, the Company enters into cross-currency swap agreements. ② Interest rate risk The Company is exposed to interest rate risk due to its borrowing with floating interest rates. A 1% increase or decrease is used when reporting interest rate risk internally to key management personnel and represents management’s assessment of the reasonably possible change in interest rates. The Company’s borrowings and debt securities with floating interest rates as of December 31, 2016 and 2017 are as follows: Type 2016 2017 In millions of won Short-term borrowings ￦ 289,322 290,873 Long-term borrowings 1,459,969 1,743,252 Debt securities 1,518,500 685,700 ￦ 3,267,791 2,719,825 A sensitivity analysis on the Company’s long-term borrowings and debt securities assuming a 1% increase and decrease in interest rates, without consideration of hedge effect of related derivatives for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 Type 1% Increase 1% Decrease 1% Increase 1% Decrease In millions of won Increase (decrease) of profit before income tax ￦ (32,678 ) 32,678 (27,198 ) 27,198 Increase (decrease) of shareholder’s equity(*) (32,678 ) 32,678 (27,198 ) 27,198 (*) The effect on the shareholders’ equity excluding the impact of income taxes. To manage its interest rate risks, the Company enters into certain interest swap agreements or maintains an appropriate mix of fixed and floating rate borrowings. ③ Electricity rates risk The Company is exposed to electricity rates risk due to the rate regulation of the government which considers the effect of electricity rate on the national economy. A sensitivity analysis on the Company’s income for the period assuming a 1% increase and decrease in price of electricity for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 Type 1% Increase 1% Decrease 1% Increase 1% Decrease In millions of won Increase (decrease) of profit before income tax ￦ 543,045 (543,045 ) 546,499 (546,499 ) Increase (decrease) of shareholder’s equity(*) 543,045 (543,045 ) 546,499 (546,499 ) (*) The effect on the shareholders’ equity excluding the impact of income taxes. (iv) Liquidity risk The Company has established an appropriate liquidity risk management framework for the management of the Company’s short, medium and long-term funding and liquidity management requirements. The Company manages liquidity risk by continuously monitoring forecasted and actual cash flows, and by matching the maturity profiles of financial assets and liabilities. In addition, the Company has established credit lines on its trade financing and bank overdrafts, and through payment guarantees it has received, it maintains an adequate credit (borrowing) line. In addition, the Company has the ability to utilize excess cash or long-term borrowings for major construction investments. The following table shows the details of maturities of non-derivative non-derivative 2016 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Borrowings and debt securities ￦ 10,613,185 9,786,209 19,353,498 24,461,835 64,214,727 Finance lease liabilities 175,512 174,534 229,495 152,247 731,788 Trade and other payables 5,464,234 307,222 660,426 2,170,525 8,602,407 Financial guarantee contracts(*) 249,200 40,617 865,842 240,493 1,396,152 ￦ 16,502,131 10,308,582 21,109,261 27,025,100 74,945,074 2017 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Borrowings and debt securities ￦ 10,748,437 7,948,320 21,331,394 22,694,867 62,723,018 Finance lease liabilities 174,534 87,709 185,284 108,749 556,276 Trade and other payables 5,867,729 301,165 698,289 1,937,558 8,804,741 Financial guarantee contracts(*) 7,081 18,054 1,049,667 80,060 1,154,862 ￦ 16,797,781 8,355,248 23,264,634 24,821,234 73,238,897 (*) This represents the total guarantee amounts associated with the financial guarantee contracts. Financial guarantee liabilities which are recognized as of December 31, 2016 and 2017 are ￦29,665 million and ￦23,475 million, respectively. The expected maturities for non-derivative 2016 Type Less than 1 year 1~5 Years More than 5 years Other(*) Total In millions of won Cash and cash equivalents ￦ 3,051,353 — — — 3,051,353 Available-for-sale — — — 1,014,732 1,014,732 Held-to-maturity 114 3,126 4 — 3,244 Loans and receivables 198,133 233,564 439,666 5,591 876,954 Long-term/short-term financial instruments 2,281,460 200,001 214,122 343 2,695,926 Trade and other receivables 7,790,953 915,679 919,901 74,199 9,700,732 ￦ 13,322,013 1,352,370 1,573,693 1,094,865 17,342,941 2017 Type Less than 1 year 1~5 Years More than 5 years Other(*) Total In millions of won Cash and cash equivalents ￦ 2,369,739 — — — 2,369,739 Available-for-sale — — 214,156 485,677 699,833 Held-to-maturity 5 3,139 — — 3,144 Loans and receivables 244,309 261,672 429,628 10,821 946,430 Long-term/short-term financial instruments 1,702,084 201,821 340,304 305 2,244,514 Financial assets at fair value through profit or loss — — 111,512 — 111,512 Trade and other receivables 7,930,715 920,539 788,795 52,031 9,692,080 ￦ 12,246,852 1,387,171 1,884,395 548,834 16,067,252 (*) The maturities cannot be presently determined. Derivative liabilities classified by maturity periods which from reporting date to maturity date of contract as of December 31, 2016 and 2017 are as follows: 2016 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Gross settlement —Trading ￦ (3,081 ) (24,044 ) — (2,799 ) (29,924 ) —Hedging (2,645 ) (2,645 ) (56,484 ) (56,575 ) (118,349 ) ￦ (5,726 ) (26,689 ) (56,484 ) (59,374 ) (148,273 ) 2017 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Net settlement —Trading ￦ (774 ) — — — (774 ) Gross settlement —Trading (51,496 ) (19,887 ) (16,597 ) (4,967 ) (92,947 ) —Hedging (17,547 ) (28,977 ) (192,205 ) (44,137 ) (282,866 ) ￦ (69,817 ) (48,864 ) (208,802 ) (49,104 ) (376,587 ) (3) Fair value risk The fair value of the Company’s actively-traded financial instruments (i.e. short-term financial assets held for trading, available-for-sale The fair values of financial instruments where no active market exists or where quoted prices are not otherwise available are determined by using valuation techniques. Valuation techniques include using recent arm’s length market transactions between knowledgeable, willing parties, if available, reference to the current fair value of another instrument that is substantially the same, discounted cash flow analysis and option pricing models. If there is a valuation technique commonly used by market participants to price the instrument and that technique has been demonstrated to provide reliable estimates of prices obtained in actual market transactions, the Company uses that technique. For trade receivables and payables, the Company considers the carrying value net of impairment as fair value. While for disclosure purposes, the fair value of financial liabilities is estimated by discounting a financial instruments with similar contractual cash flows based on the effective interest method. (i) Fair value and book value of financial assets and liabilities as of December 31, 2016 and 2017 are as follows: 2016 2017 Type Book value Fair value Book value Fair value In millions of won Assets recognized at fair value Available-for-sale ￦ 1,014,732 1,014,732 699,833 699,833 Derivative assets (trading) 367,477 367,477 22,020 22,020 Derivative assets (using hedge accounting) 413,897 413,897 10,606 10,606 Long-term financial instruments 414,466 414,466 542,430 542,430 Short-term financial instruments 2,281,460 2,281,460 1,702,084 1,702,084 Financial assets at fair value through profit or loss — — 111,512 111,512 4,492,032 4,492,032 3,088,485 3,088,485 Assets carried at amortized cost Held-to-maturity 3,244 3,244 3,144 3,144 Loans and receivables 834,207 834,207 905,641 905,641 Trade and other receivables 9,692,391 9,692,391 9,683,769 9,683,769 Cash and cash equivalents 3,051,353 3,051,353 2,369,739 2,369,739 13,581,195 13,581,195 12,962,293 12,962,293 Liabilities recognized at fair value Derivative liabilities (trading) 21,529 21,529 150,929 150,929 Derivative liabilities (using hedge accounting) 117,157 117,157 277,130 277,130 138,686 138,686 428,059 428,059 Liabilities carried at amortized cost Secured borrowings 744,565 744,565 1,055,554 1,055,554 Unsecured bond 50,749,793 54,455,659 51,146,783 53,436,659 Finance lease liabilities 541,179 541,179 418,260 418,260 Unsecured borrowings 2,089,885 2,099,574 2,476,196 2,477,055 Trade and other payables(*2) 8,602,407 8,602,407 8,804,741 8,804,741 Bank overdraft 54,962 54,962 68,859 68,859 ￦ 62,782,791 66,498,346 63,970,393 66,261,128 (*1) Book values of equity securities held by the Company that were measured at cost as of December 31, 2016 and 2017 are ￦138,557 million and ￦37,926 million, respectively, as a quoted market price does not exist in an active market and its fair value cannot be measured reliably. (*2) Excludes finance lease liabilities. (ii) Interest rates used for determining fair value The interest rates used to discount estimated cash flows, when applicable, are based on the government yield curve at the reporting date plus an adequate credit spread. The discount rate used for calculating fair value as of December 31, 2016 and 2017 are as follows: Type 2016 2017 Derivatives 0.02% ~ 4.16% 0.03% ~ 4.16% Borrowings and debt securities 0.02% ~ 4.38% 0.08% ~ 4.38% Finance lease 9.00% ~ 10.83% 9.00% ~ 10.83% (iii) Fair value hierarchy The following table provides an analysis of financial instruments that are measured subsequent to initial recognition at fair value, classified as Level 1, 2 or 3, based on the degree to which the fair value is observable. Level 1: Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2: Inputs other than quoted prices that are observable for the asset or liability either directly or indirectly; and Level 3: Inputs that are not based on observable market data. Fair values of financial instruments by hierarchy level as of December 31, 2016 and 2017 are as follows: 2016 Type Level 1 Level 2 Level 3 Total In millions of won Financial assets at fair value Available-for-sale ￦ 268,171 437,015 269,461 974,647 Derivative assets — 770,851 10,523 781,374 268,171 1,207,866 279,984 1,756,021 Financial liabilities at fair value Derivative liabilities — 138,686 — 138,686 2017 Type Level 1 Level 2 Level 3 Total In millions of won Financial assets at fair value Available-for-sale ￦ 274,453 214,156 173,298 661,907 Derivative assets — 18,466 14,160 32,626 Financial assets at fair value through profit or loss — 111,512 — 111,512 274,453 344,134 187,458 806,045 Financial liabilities at fair value Derivative liabilities — 428,059 — 428,059 The fair value of available-for-sale available-for-sale Changes of financial assets and liabilities which are classified as level 3 for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Acquisition Reclassified Valuation Disposal Foreign Ending In millions of won Financial assets at fair value Available-for-sale Unlisted securities ￦ 180,390 — 98,472 (9,401 ) — — 269,461 2017 Beginning Acquisition Reclassified Valuation Disposal Foreign Ending In millions of won Financial assets at fair value Available-for-sale Unlisted securities ￦ 269,461 — (92,128 ) (6,201 ) — 2,166 173,298

Service Concession Arrangements

Service Concession Arrangements	12 Months Ended
	Dec. 31, 2017
Service Concession Arrangements [Abstract]
Service Concession Arrangements	46. Service Concession Arrangements (1) Gas Complex (i) Significant terms and concession period of the arrangement The Company has entered into a contract with National Power Corporation (the “NPC”), based in the Republic of the Philippines whereby the Company can collect the electricity rates which are composed of fixed costs and variable costs during the concession period from 2002 to 2022 after building, rehabilitating, and operating the power plant. (ii) Rights and classification of the arrangement The Company has the rights to use and own the power plant during the concession period from 2002 to 2022. At the end of the concession period, the Company has an obligation to transfer its ownership of the power plant to NPC. (iii) The Company’s expected future collections of service concession arrangements as of December 31, 2017 are as follows: Type Amounts In millions of won Less than 1 year ￦ 111,912 1 ~ 2 years 111,912 2 ~ 3 years 111,912 Over 3 years 158,543 ￦ 494,279 (2) Hydroelectric Power Generation at Semangka, Indonesia (BOT) (i) Significant terms and concession period of the arrangement The Company has entered into a contract with PT. Perusahaan Listrik Negara (the “PLN”) whereby the Company provides electricity generated and charge tariff rates designed to recover capital cost, fixed O&M cost, water usage cost, variable O&M cost and special facilities cost during the concession period after building, rehabilitating, and operating the power plant for approximately 30 years (2018~2048) subsequent to the completion of plant construction. (ii) Rights and classification of the arrangement The Company has the rights to use and own the power plant during the concession period from 2018 to 2048. At the end of the concession period, PNL has an option to take over the ownership of the power plant from the Company. (iii) The Company’s expected future collections of service concession arrangements as of December 31, 2017 are as follows: Type Amounts In millions of won Less than 1 year ￦ 20,332 1 ~ 2 years 26,888 2 ~ 3 years 26,888 Over 3 years 591,687 ￦ 665,795 (iv) Accumulated contract costs and profits related to the Company’s contract in process as of December 31, 2017 were ￦145,613 million and ￦9,163 million, respectively. There are no amount due from customers and advance receipts in progress.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Parties [Abstract]
Related Parties	47. Related Parties (1) Related parties of the Company as of December 31, 2017 are as follows: Type Related party Parent Republic of Korea government Subsidiaries (100 subsidiaries) Korea Hydro & Nuclear Power Co., Ltd., Korea South-East Power Co., Ltd., Korea Midland Power Co., Ltd., Korea Western Power Co., Ltd., Korea Southern Power Co., Ltd., Korea East-West Power Co., Ltd., KEPCO Engineering & Construction Company, Inc., KEPCO Plant Service & Engineering Co., Ltd., KEPCO Nuclear Fuel Co., Ltd., KEPCO KDN Co., Ltd., Garolim Tidal Power Plant Co., Ltd., Gyeonggi Green Energy Co., Ltd., Korea Offshore Wind Power Co., Ltd., KOSEP Material Co., Ltd., KEPCO International HongKong Ltd., KEPCO International Philippines Inc., KEPCO Philippines Corporation, KEPCO Ilijan Corporation, KEPCO Gansu International Ltd., KEPCO Philippines Holdings Inc., KEPCO Lebanon SARL, KEPCO Neimenggu International Ltd., KEPCO Australia Pty., Ltd., KEPCO Shanxi International Ltd., KOMIPO Global Pte Ltd., KOSEP Australia Pty., Ltd., KOMIPO Australia Pty., Ltd., KOWEPO Australia Pty., Ltd., KOSPO Australia Pty., Ltd., KEPCO Canada Energy Ltd., KEPCO Netherlands B.V., KOREA Imouraren Uranium Investment Corp., KEPCO Middle East Holding Company, Qatrana Electric Power Company, Korea Electric Power Nigeria Ltd., KOWEPO International Corporation, KOSPO Jordan LLC, Korea Waterbury Uranium Limited Partnership, PT. Cirebon Power Service, EWP America Inc., KHNP Canada Energy, Ltd., KEPCO Bylong Australia Pty., Ltd., KNF Canada Energy Limited, KEPCO Holdings de Mexico, KST Electric Power Company, KEPCO Energy Service Company, KEPCO Netherlands S3 B.V., PT. KOMIPO Pembangkitan Jawa Bali, PT KEPCO Resource Indonesia, EWP (Barbados) 1 SRL, PT. Tanggamus Electric Power, KOMIPO America Inc, KOSEP USA, INC., PT. EWP Indonesia, KEPCO Netherlands J3 B.V., Global One Pioneer B.V., Global Energy Pioneer B.V., Mira Power Limited, EWP Philippines Corporation, KEPCO Singapore Holdings Pte., Ltd., KOWEPO India Private Limited, KEPCO KPS Philippines Corp., KOSPO Chile SpA, PT. KOWEPO Sumsel Operation And Maintenance Services, Commerce and Industry Energy Co., Ltd., Gyeongju Wind Power Co., Ltd., California Power Holdings, LLC, DG Fairhaven Power, LLC, DG Whitefield, LLC, EWP Renewable Corporation, EWPRC Biomass Holdings, LLC, Springfield Power, LLC, HeeMang Sunlight Power Co., Ltd., Fujeij Wind Power Company, KOSPO Youngnam Power Co., Ltd., HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2), Chitose Solar Power Plant LLC., Solar School Plant Co., Ltd., KEPCO Energy Solution Co. Ltd., KOSPO Power Services Limitada, KOEN Bylong Pty., Ltd., KOWEPO Bylong Pty., Ltd., KOSPO Bylong Pty., Ltd., EWP Bylong Pty., Ltd., KOWEPO Lao International, KOMIPO Bylong Pty Ltd., Energy New Industry Specialized Investment Private Investment Trust., KEPCO US Inc., KEPCO Alamosa LLC, Cogentrix Solar Services, LLC, Solar Investments I, LLC, Cogentrix of Alamosa, LLC, KEPCO-LG KEPCO-LG e-New e-New E-New Associates (56 associates) Dongducheon Dream Power Co., Ltd., Korea Gas Corporation, SE Green Energy Co., Ltd., Daegu Photovoltaic Co., Ltd., Jeongam Wind Power Co., Ltd., Korea Power Engineering Service Co., Ltd., Heang Bok Do Si Photovoltaic Power Co., Ltd., Korea Electric Power Industrial Development Co., Ltd., Goseong Green Energy Co., Ltd., Gangneung Eco Power Co., Ltd., Shin Pyeongtaek Power Co., Ltd., Naepo Green Energy Co., Ltd., Noeul Green Energy Co., Ltd., YTN Co., Ltd., Cheongna Energy Co., Ltd., Samcheok Eco Materials Co., Ltd., Gangwon Wind Power Co., Ltd., Gwangyang Green Energy Co., Ltd., Hyundai Green Power Co., Ltd., Korea Power Exchange, AMEC Partners Korea Ltd., Hyundai Energy Co., Ltd., Ecollite Co., Ltd., Taebaek Wind Power Co., Ltd., Taeback Guinemi Wind Power Co., Ltd., Pyeongchang Wind Power Co., Ltd., Daeryun Power Co., Ltd., Changjuk Wind Power Co., Ltd., KNH Solar Co., Ltd., S-Power Xe-Pian Xe-Namnoy Nuclear Partners Co., Ltd., Tamra Offshore Wind Power Co., Ltd., Korea Electric Power Corporation Fund, Energy Infra Asset Management Co., Ltd., Daegu clean Energy Co., Ltd., YaksuESS Co., Ltd, PND solar., Ltd Joint ventures (45 joint ventures) Daegu Green Power Co., Ltd., KEPCO SPC Power Corporation, Daejung Offshore Wind Power Co., Ltd., KAPES, Inc., Dangjin Eco Power Co., Ltd., Honam Wind Power Co., Ltd., Seokmun Energy Co., Ltd., Incheon New Power Co., Ltd., Chun-cheon Energy Co., Ltd., Yeonggwangbaeksu Wind Power Co., Ltd., KW Nuclear Components Co., Ltd., KEPCO-Uhde Inc., GS Donghae Electric Power Co., Ltd., Busan Shinho Solar Power Co., Ltd., Global Trade Of Power System Co., Ltd., Expressway Solar-light Power Generation Co., Ltd., Gansu Datang Yumen Wind Power Co., Ltd., Datang Chifeng Renewable Power Co., Ltd., Rabigh Electricity Company, Eco Biomass Energy Sdn. Bhd., Rabigh Operation & Maintenance Company Limited, Datang KEPCO Chaoyang Renewable Power Co., Ltd., Shuweihat Asia Power Investment B.V., Shuweihat Asia Operation & Maintenance Company, Waterbury Lake Uranium L.P., ASM-BG Others (3 others) Korea Development Bank, Yeongwol Energy Station Co., Ltd., DS POWER Co., Ltd. (2) Transactions between the Company and its subsidiaries are eliminated during the consolidation and are not disclosed in notes. (3) Related party transactions for the years ended December 31, 2015, 2016 and 2017 are as follows: <Sales and Others> Sales and others Company name Transaction type 2015 2016 2017 In millions of won <Associates> Daegu Green Power Co., Ltd. Electricity sales ￦ 1,055 — — Dongducheon Dream Power Co., Ltd. Electricity sales 14,811 15,221 17,041 Korea Gas Corporation Electricity sales 90,480 89,030 88,011 Daegu Photovoltaic Co., Ltd. Service — — 349 Jeongam Wind Power Co., Ltd. Electricity sales 8 6 30 Korea Power Engineering Service Co., Ltd. Service 1,743 1,455 1,317 KS Solar Co., Ltd. Electricity sales 21 20 5 Heang Bok Do Si Photovoltaic Power Co., Ltd. Service 1 2 2 Korea Electric Power Industrial Development Co., Ltd. Service 12,361 10,723 14,044 Goseong Green Energy Co., Ltd. Electricity sales 9,306 9,195 24,069 Gangneung Eco Power Co., Ltd. Service 9,761 5,223 2,391 Shin Pyeongtaek Power Co., Ltd. Electricity sales 11,344 3,579 9,025 Naepo Green Energy Co., Ltd. Electricity sales 66 104 185 Noeul Green Energy Co., Ltd. Electricity sales ￦ 45 177 32 Samcheok Eco Materials Co., Ltd. Electricity sales — 64 237 YTN Co., Ltd. Electricity sales 1,753 1,785 1,987 Busan Green Energy Co., Ltd. Service 1 133 120 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) Electricity sales — 6 — Korea Electric Vehicle Charging Service Electricity sales 2 89 700 Ulleungdo Natural Energy Co., Ltd. Service 229 691 1,013 Tamra Offshore Wind Power Co., Ltd. Service — 12 55 Daegu clean Energy Co., Ltd. Electricity sales — — 421 Cheongna Energy Co., Ltd. Service 21,081 6,831 7,980 Gangwon Wind Power Co., Ltd. Electricity sales 1,046 1,273 994 Hyundai Green Power Co., Ltd. Design service 15,401 14,835 14,280 Korea Power Exchange Service 4,272 7,141 8,446 Hyundai Energy Co., Ltd. Service 25,402 24,719 15,627 Taebaek Wind Power Co., Ltd. Service 872 796 813 Pyeongchang Wind Power Co., Ltd. Design service 72 497 1,176 Daeryun Power Co., Ltd. Electricity sales 1,731 1,516 1,796 Changjuk Wind Power Co., Ltd. Electricity sales 754 863 788 KNH Solar Co., Ltd. Electricity sales 17 17 17 S-Power Service 7,278 5,994 12,852 Busan Solar Co., Ltd. Electricity sales 16 8 — Green Biomass Co., Ltd. Electricity sales 51 2 — SPC Power Corporation Dividend income 1,433 8,346 5,562 Gemeng International Energy Co., Ltd. Dividend income 37,163 16,476 13,365 PT. Cirebon Electric Power Dividend income — — 550 Dolphin Property Limited Dividend income — 35 — PT. Bayan Resources TBK Service 164 160 717 Nepal Water & Energy Development Company Private Limited Service — 375 900 Pioneer Gas Power Limited Service 274 164 62 Xe-Pian Xe-Namnoy Service 584 773 661 PT. Mutiara Jawa Service — — 47 <Joint ventures> Daegu Green Power Co., Ltd. Electricity sales — 768 1,131 KEPCO SPC Power Corporation Service 29,572 10,344 45,005 Daejung Offshore Wind Power Co., Ltd. Electricity sales 1 1 1 KAPES, Inc. Commission 1,315 1,176 1,420 Dangjin Eco Power Co., Ltd. Technical fee 334 1,787 670 Honam Wind Power Co., Ltd. Electricity sales 65 169 552 Seokmun Energy Co., Ltd. Service 2,395 1,627 1,765 Incheon New Power Co., Ltd. Construction revenue 388 524 539 Chun-cheon Energy Co., Ltd. Electricity sales 2,201 3,079 4,855 Yeonggwangbaeksu Wind Power Co., Ltd. Electricity sales 927 1,591 1,654 KW Nuclear Components Co., Ltd. Service 1,948 3,327 644 KEPCO-Uhde Inc. Service — 6 34 GS Donghae Electric Power Co., Ltd. Electricity sales 5,614 12,994 11,204 Busan Shinho Solar Power Co., Ltd. Electricity sales 24 210 87 Datang Chifeng Renewable Power Co., Ltd. Interest income 9,702 8,216 500 Rabigh Electricity Company Dividend income 565 699 19,179 Rabigh Operation & Maintenance Company Limited Dividend income 1,780 2,395 2,784 Datang Chaoyang Renewable Power Co., Ltd. Dividend income ￦ — — 839 Shuweihat Asia Power Investment B.V. Dividend income — 2,957 1,707 Shuweihat Asia Operation & Maintenance Company Electricity sales 1,006 1,179 1,319 ASM-BG Service — 322 1,062 Jamaica Public Service Company Limited Service 3,077 1,905 — KV Holdings, Inc. Dividend income — 302 — Datang KEPCO Chaoyang Renewable Co., Ltd. Dividend income — 440 — Amman Asia Electric Power Company Service 48,968 21,915 14,205 Kelar S.A Service 6,229 1,702 570 Nghi Son 2 Power Ltd. Electricity sales — — 2,693 Barakah One Company Electricity sales — 25,244 7,059 Nawah Energy Company Service — — 34,421 <Others> Yeongwol Energy Station Co., Ltd. Service 814 858 830 DS POWER Co., Ltd. Service 106,183 35,133 5,819 Korea Development Bank Electricity sales 4,039 3,102 3,239 Interest income 2,402 3,164 1,685 <Purchase and Others> Purchase and others Company name Transaction type 2015 2016 2017 In millions of won <Associates> Dongducheon Dream Power Co., Ltd. Electricity purchase ￦ 1,003,346 946,463 813,440 Korea Gas Corporation Purchase of power generation fuel 4,598,763 3,633,198 3,245,519 Daegu Photovoltaic Co., Ltd. REC purchase 3,978 3,243 3,646 Korea Power Engineering Service Co., Ltd. Service 3,241 723 1,292 KS Solar Co., Ltd. REC purchase 6,211 4,080 900 Heang Bok Do Si Photovoltaic Power Co., Ltd. Rental fee and others 479 410 570 Korea Electric Power Industrial Development Co., Ltd. Electricity metering service fee 273,057 250,057 289,293 Noeul Green Energy Co., Ltd. Service — — 15,862 Samcheok Eco Materials Co., Ltd. Electricity purchase — — 14 YTN Co., Ltd. Advertisement fee 440 554 731 Busan Green Energy Co., Ltd. Service — — 12,189 Korea Electric Vehicle Charging Service Service — — 1,093 Ulleungdo Natural Energy Co., Ltd. Electricity purchase — 60 119 Tamra Offshore Wind Power Co., Ltd. Electricity purchase — — 2,105 Cheongna Energy Co., Ltd. Service — 73 59 Gangwon Wind Power Co., Ltd. Electricity purchase 21,946 22,780 25,968 Hyundai Green Power Co., Ltd. Electricity purchase 486,443 469,547 458,378 Korea Power Exchange Trading Fees 79,283 91,433 207,855 Hyundai Energy Co., Ltd. Electricity purchase 1,684 1,313 87,607 Taebaek Wind Power Co., Ltd. REC purchase 6,626 5,741 6,534 Pyeongchang Wind Power Co., Ltd. Service — 1,594 4,033 Daeryun Power Co., Ltd. Electricity purchase 274,379 244,023 146,189 Changjuk Wind Power Co., Ltd. Electricity purchase 6,472 5,786 6,981 KNH Solar Co., Ltd. Electricity purchase ￦ 4,598 4,006 3,947 S-Power Electricity purchase 614,658 437,206 457,329 Busan Solar Co., Ltd. Electricity purchase 4,055 1,079 — Green Biomass Co., Ltd. Woodchip purchase 3,782 2,232 1,345 Nepal Water & Energy Development Company Private Limited Service — — 72 <Joint ventures> Daegu Green Power Co., Ltd. Electricity purchase 318,221 263,797 252,024 KAPES, Inc. Service 47,130 140,555 164,165 Honam Wind Power Co., Ltd. Electricity purchase 5,944 6,776 5,962 Seokmun Energy Co., Ltd. REC purchase — — 21,674 Chun-cheon Energy Co., Ltd. REC purchase — — 194,136 Yeonggwangbaeksu Wind Power Co., Ltd. Electricity purchase 4,974 11,208 11,124 GS Donghae Electric Power Co., Ltd. Electricity purchase — 903 351,367 Busan Shinho Solar Power Co., Ltd. REC purchase 7,565 6,770 7,984 Global Trade Of Power System Co., Ltd. Service 192 882 414 Expressway Solar-light Power Generation Co., Ltd. Electricity purchase 3,451 2,942 2,941 Jamaica Public Service Company Limited Service 106 127 154 Amman Asia Electric Power Company Service 125 — — Barakah One Company Service — — 2,631 <Others> Yeongwol Energy Station Co., Ltd. REC purchase 16,408 14,875 14,256 Korea Development Bank Interest expense 21,719 8,231 4,573 Dividend paid 96,087 654,829 418,407 (4) Receivables and payables arising from related party transactions as of December 31, 2016 and 2017 are as follows: Receivables Payables Company name Type 2016 2017 2016 2017 In millions of won <Associates> Dongducheon Dream Power Co., Ltd. Trade receivables ￦ 1,073 2,230 — — Non-trade — 655 — — Trade payables — — 93,493 77,817 Korea Gas Corporation Trade receivables 8,739 9,833 — — Non-trade 78 339 — — Trade payables — — 399,563 524,881 Non-trade — — 9,090 569 Daegu Photovoltaic Co., Ltd. Trade payables — — 56 71 Jeongam Wind Power Co., Ltd. Non-trade — — 4 4 KS Solar Co., Ltd. Trade receivables 2 — — — Trade payables — — 53 — Korea Electric Power Industrial Development Co., Ltd. Trade receivables 362 333 — — Non-trade 47 42 — — Non-trade — — 18,628 18,006 Goseong Green Energy Co., Ltd. Non-trade — 19 — — Non-trade — — 3,900 7,140 Gangneung Eco Power Co., Ltd. Trade receivables ￦ 1 1 — — Non-trade 2,137 4,747 — — Shin Pyeongtaek Power Co., Ltd. Non-trade 215 210 — — Non-trade — — — 52 Naepo Green Energy Co., Ltd. Trade receivables 14 17 — — Noeul Green Energy Co., Ltd. Trade receivables 18 3 — — Non-trade — — — 2,041 Samcheok Eco Materials Co., Ltd. Trade receivables 21 20 — — YTN Co., Ltd. Trade receivables 165 98 — — Non-trade — — 132 209 Busan Green Energy Co., Ltd. Trade receivables 9 7 — — Non-trade — 1,691 — — Korea Electric Vehicle Charging Service Trade receivables 12 23 — — Trade payables — — — 45 Ulleungdo Natural Energy Co., Ltd. Non-trade 111 — — — Cheongna Energy Co., Ltd. Trade receivables 165 182 — — Non-trade — — 82 1 Gangwon Wind Power Co., Ltd. Trade receivables 8 6 — — Trade payables — — 2,031 3,033 Hyundai Green Power Co., Ltd. Trade receivables 569 946 — — Trade payables — — 31,507 32,589 Korea Power Exchange Trade receivables 1,066 463 — — Non-trade 53 128 — — Non-trade — — 1,235 1,142 Hyundai Energy Co., Ltd. Trade receivables 72 49 — — Non-trade 68,798 6,598 — — Trade payables — — 86 223 Non-trade — — — 13,796 Ecollite Co., Ltd. Non-trade 210 210 — — Taebaek Wind Power Co., Ltd. Trade receivables — 116 — — Non-trade 112 — — — Trade payables — — 386 533 Non-trade — — 304 121 Pyeongchang Wind Power Co., Ltd. Trade receivables 4 3 — — Non-trade — — 255 163 Daeryun Power Co., Ltd. Trade receivables 140 162 — — Trade payables — — 21,646 15,706 Changjuk Wind Power Co., Ltd. Trade receivables 100 101 — — Trade payables — — 358 515 Non-trade — — 334 546 KNH Solar Co., Ltd. Trade receivables 1 1 — — Non-trade — — 204 193 S-Power Trade receivables 142 117 — — Non-trade 393 5,183 — — Trade payables — — 51,844 25,061 Green Biomass Co., Ltd. Non-trade ￦ — — 113 85 SPC Power Corporation Non-trade — 76 — — Nepal Water & Energy Development Company Private Limited Non-trade 889 227 — — Pioneer Gas Power Limited Non-trade 82 — — — Xe-Pian Xe-Namnoy Non-trade 58 53 — — <Joint ventures> Daegu Green Power Co., Ltd. Trade receivables 52 98 — — Non-trade 1 10 — — Trade payables — — 27,400 25,257 KEPCO SPC Power Corporation Non-trade 2,349 — — — KAPES, Inc. Non-trade 235 — — — Trade payables — — — 55 Non-trade — — 11,992 — Dangjin Eco Power Co., Ltd. Non-trade 833 1,211 — — Non-trade — — — 41 Honam Wind Power Co., Ltd. Trade payables — — 424 381 Non-trade — — 3,082 3,013 Seokmun Energy Co., Ltd. Trade receivables 114 93 — — Non-trade 160 276 — — Non-trade — — — 3,052 Incheon New Power Co., Ltd. Trade receivables 128 128 — — Chun-cheon Energy Co., Ltd. Trade receivables — 129 — — Non-trade 255 252 — — Trade payables — — — 29,676 Yeonggwangbaeksu Wind Power Co., Ltd. Trade receivables 6 7 — — Non-trade 145 144 — — Trade payables — — 761 619 Non-trade — — 1,362 1,300 KW Nuclear Components Co., Ltd. Trade receivables — 4 — — KEPCO-Uhde Inc. Non-trade — — 4 4 GS Donghae Electric Power Co., Ltd. Trade receivables 775 450 — — Non-trade 1,497 1,892 — — Trade payables — — — 73,570 Non-trade — — 993 — Busan Shinho Solar Power Co., Ltd. Trade receivables 3 2 — — Trade payables — — 129 159 Non-trade — — 670 811 Datang Chifeng Renewable Power Co., Ltd. Non-trade 210 82 — — Rabigh Operation & Maintenance Company Limited Trade receivables 2,275 — — — Non-trade — 869 — — ASM-BG Non-trade 64 37 — — Jamaica Public Service Company Limited Trade receivables 615 — — — Amman Asia Electric Power Company Trade receivables 2,509 2,675 — — Nawah Energy Company Trade receivables — 10,419 — — <Others> Yeongwol Energy Station Co., Ltd. Trade receivables 7,064 7,068 — — Trade payables — — 229 — DS POWER Co., Ltd. Trade receivables 1,775 340 — — Korea Development Bank Accrued interest income 672 204 — — Non-trade 217,481 501,029 — — Non-trade — — 408 200 Derivatives 25,306 569 3,278 22,398 (5) Loans and others arising from related party transactions as of December 31, 2016 and 2017 are as follows: Type Company name Beginning Loans Collection Others Ending balance In millions of won Associates KNOC Nigerian East Oil Co., Ltd., KNOC Nigerian West Oil Co., Ltd. ￦ 29,282 169 — (3,110 ) 26,341 (Allowance for doubtful accounts) (18,191 ) — — 1,640 (16,551 ) Associates PT. Cirebon Electric Power 26,733 2,199 (7,876 ) (5,620 ) 15,436 Associates Xe-Pian Xe-Namnoy 1,413 — — — 1,413 Associates PT Wampu Electric Power 14,022 905 — (1,639 ) 13,288 Associates Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 9,396 — — — 9,396 Associates Hyundai Energy Co., Ltd. 2,465 — — — 2,465 (Allowance for doubtful accounts) — — — (2,465 ) (2,465 ) Joint ventures KEPCO SPC Power Corporation 27,795 — (7,803 ) (2,743 ) 17,249 Joint ventures Datang Chifeng Renewable Power Co., Ltd. 16,344 — (7,647 ) (1,452 ) 7,245 Joint ventures Rabigh Electricity Company 2,641 — (2,496 ) (145 ) — Joint ventures KODE NOVUS II LLC 4,532 — — (514 ) 4,018 (Allowance for doubtful accounts) (4,532 ) — — 514 (4,018 ) Joint ventures Kelar S.A — 54,631 (3,568 ) (4,443 ) 46,620 Joint ventures Daehan Wind Power PSC 683 640 — (112 ) 1,211 Joint ventures Chester Solar IV SpA — 4,802 — (195 ) 4,607 ￦ 112,583 63,346 (29,390 ) (20,284 ) 126,255 (6) Borrowings arising from related party transactions as of December 31, 2016 and 2017 are as follows: Related parties Type Beginning balance Borrowings Repayment Others Ending balance In millions of won Korea Development Facility ￦ 207,993 27,324 (141,434 ) — 93,883 Bank Others 5,663 — (754 ) — 4,909 Operating funds 37,000 49,000 (25,000 ) — 61,000 Syndicated Loan 6,075 11,855 — (1,629 ) 16,301 (7) Guarantees provided to associates or joint ventures as of December 31, 2017 are as follows: Primary guarantor Principal obligor Type of guarantees Credit limit Guarantee In millions of won and thousands of foreign currencies Korea Electric Power Corporation Shuweihat Asia Operation & Maintenance Company Performance guarantees USD 11,000 SAPCO Korea Electric Power Corporation KNOC Nigerian East Oil Co., Ltd. and KNOC Nigerian West Oil Co., Ltd. Performance guarantees USD 34,650 Korea National Oil Corporation (Nigerian government) Korea Electric Power Corporation Rabigh Operation & Maintenance Company Limited Performance guarantees and others USD 1,387 RABEC Korea Electric Power Corporation Nghi Son 2 Power Ltd. Bidding guarantees USD 10,000 SMBC Ho Chi Minh Korea Electric Power Corporation Barakah One Company Debt guarantees USD 900,000 Export-Import Bank of Korea and others Performance guarantees and others USD 3,404,275 Korea Western Power Co., Ltd. Cheongna Energy Co., Ltd. Collateralized money invested KRW 27,211 KEB Hana Bank and others Guarantees for supplemental funding and others (*1) — Korea Western Power Co., Ltd. Xe-Pian Xe-Namnoy Payment guarantees for business reserve USD 2,500 Krung Thai Bank Collateralized money invested USD 62,253 Krung Thai Bank Impounding bonus guarantees USD 5,000 SK E&C Korea Western Power Co., Ltd. Rabigh Operation & Maintenance Company Limited Performance guarantees and others SAR 5,600 Saudi Arabia British Bank Korea Western Power Co., Ltd. Daegu Photovoltaic Co., Ltd. Collateralized money invested KRW 1,230 Korea Development Bank Korea Western Power Co., Ltd. Dongducheon Dream Power Co., Ltd. Collateralized money invested KRW 53,233 Kookmin Bank and others Korea Western Power Co., Ltd. PT. Mutiara Jawa Collateralized money invested USD 2,610 Woori Bank Korea Western Power Co., Ltd. Heang Bok Do Si Photovoltaic Power Co., Ltd. Collateralized money invested KRW 194 Nonghyup Bank Korea Western Power Co., Ltd. Shin Pyeongtaek Power Co., Ltd. Collateralized money invested KRW 43,920 Kookmin Bank Korea East-West Power Co., Ltd. Busan Shinho Solar Power Co., Ltd. Collateralized money invested KRW 2,100 Korea Development Bank and others Korea East-West Power Co., Ltd. Seokmun Energy Co., Ltd. Collateralized money invested KRW 15,370 Kookmin Bank and others Korea East-West Power Co., Ltd. Chun-cheon Energy Co., Ltd. Collateralized money invested KRW 52,700 Kookmin Bank and others Guarantees for supplemental funding(*1) KRW 60,270 Kookmin Bank and others Korea East-West Power Co., Ltd. Honam Wind Power Co., Ltd. Collateralized money invested KRW 3,480 Shinhan Bank and others Korea East-West Power Co., Ltd. GS Donghae Electric Power Co., Ltd. Collateralized money invested KRW 204,000 Korea Development Bank and others Korea East-West Power Co., Ltd. Yeonggwangbaeksu Wind Power Co., Ltd. Collateralized money invested KRW 3,000 Kookmin Bank and others Korea East-West Power Co., Ltd. Yeonggwang Wind Power Co., Ltd. Collateralized money invested KRW 15,375 KEB Hana Bank and others Korea East-West Power Co., Ltd. PT. Tanjung Power Indonesia Debt guarantees USD 46,983 The Bank of Tokyo-Mitsubishi and others Other guarantees USD 3,150 PT Adaro Indonesia EWP Barbados 1 SRL South Jamaica Power Company Limited Performance guarantees USD 14,400 Societe Generale Guarantees for supplemental funding and others(*1, 3) USD 60,000 JCSD Trustee Services Limited and others Korea Southern Power Co., Ltd. KNH Solar Co., Ltd. Collateralized money invested KRW 1,296 Shinhan Bank and Kyobo Life Insurance Co., Ltd. Performance guarantees and guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Daeryun Power Co., Ltd. Collateralized money invested KRW 25,477 Korea Development Bank and others Guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Changjuk Wind Power Co., Ltd. Collateralized money invested KRW 3,801 Shinhan Bank Guarantees for supplemental funding(*1) — Korea Southern Power Co., Ltd. Daegu Green Power Co., Ltd. Collateralized money invested KRW 46,226 Shinhan Bank Korea Southern Power Co., Ltd. Kelar S.A Performance guarantees USD 63,707 KEB Hana Bank, SMBC, Mizuho Bank and others Korea Southern Power Co., Ltd. DS POWER Co., Ltd. Collateralized money invested KRW 2,900 Korea Development Bank and others Guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Pyeongchang Wind Power Co., Ltd. Collateralized money invested KRW 3,875 Woori Bank and Shinhan Bank Performance guarantees and guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Taebaek Wind Power Co., Ltd. Guarantees for supplemental funding and others(*1) — Shinhan Bank Korea Southern Power Co., Ltd. Jeongam Wind Power Co., Ltd Collateralized money invested Guarantees for supplemental funding and others (*1) KRW 5,580 — SK Securities Co., Ltd. Korea Southern Power Co., Ltd. Naepo Green Energy Co., Ltd. KRW 29,200 Hana Financial Investment Co., Ltd. and others Guarantees for supplemental funding and others (*1) — KEPCO Engineering & Construction Company, Inc. DS POWER Co., Ltd. Collateralized money invested KRW 15,000 Korea Development Bank and others Korea Midland Power Co., Ltd. Hyundai Green Power Co., Ltd. Collateralized money invested KRW 87,003 Korea Development Bank and others Guarantees for supplemental funding and others (*1) — Korea Midland Power Co., Ltd. PT. Cirebon Electric Power Debt guarantees USD 11,550 Mizuho Bank Korea Midland Power Co., Ltd. PT Wampu Electric Power Debt guarantees USD 5,068 SMBC Korea Midland Power Co., Ltd. Gangwon Wind Power Co., Ltd. Collateralized money invested KRW 7,409 IBK and others Korea Midland Power Co., Ltd. YaksuESS Co., Ltd Collateralized money invested KRW 210 Hanwha Life Insurance Co., Ltd. Guarantees for supplemental funding and others (*1) — Korea South-East Power Co., Ltd. Hyundai Energy Co., Ltd. Collateralized money invested KRW 47,067 Korea Development Bank and others Performance guarantees and guarantees for supplemental funding and others (*1) KRW 78,600 Korea South-East Power Co., Ltd. RES Technology AD Collateralized money invested KRW 15,595 UniCredit Bulbank and others Korea South-East Power Co., Ltd. ASM-BG Collateralized money invested KRW 16,101 UniCredit Bulbank and others Korea South-East Power Co., Ltd. Express Solar-light Power Generation Co., Ltd. Guarantees for supplemental funding (*1, 2) KRW 2,500 Woori Bank Korea South-East Power Co., Ltd. S-Power Collateralized money invested KRW 132,300 Korea Development Bank and others KOSEP USA, INC. KODE NOVUS II LLC Guarantees for supplemental funding and others (*1) — Korea Development Bank KOSEP USA, INC. KODE NOVUS I LLC Guarantees for supplemental funding and others (*1) — Export-Import Bank of Korea and others Korea Hydro & Nuclear Power Co., Ltd. Yeongwol Energy Station Co., Ltd. Collateralized money invested KRW 1,400 Meritz Fire & Marine Insurance Co., Ltd. Korea Hydro & Nuclear Power Co., Ltd. Noeul Green Energy Co., Ltd., Collateralized money invested KRW 1,740 KEB Hana Bank and others Korea Hydro & Nuclear Power Co., Ltd. Busan Green Energy Co., Ltd. Collateralized money invested KRW 5,243 Shinhan Bank and others KEPCO Plant Service & Engineering Co., Ltd. Incheon New Power Co., Ltd. Collateralized money invested KRW 8,160 Shinhan Bank Guarantees for supplemental funding and others (*1) — (*1) The Company guarantees to provide supplemental funding for business with respect to excessive business expenses or insufficient repayment of borrowings. (*2) The Company has granted the right to Hana Financial Investment Co., Ltd., as an agent for the creditors to Express Solar-light Power Generation Co., Ltd. (“ESPG”), to the effect that in the event of acceleration of ESPG’s payment obligations under certain borrowings to such creditors, Hana Financial may demand the Company to dispose of shares in ESPG held by the Company and apply the resulting proceeds to repayment of ESPG’s obligations. (*3) This includes a guarantee for the shareholder’s capital payment in connection with the business of 190MW gas complex thermal power plant in Jamaica. EWP (Barbados) 1 SRL’s capital contribution amount is USD 6,400 thousand and the total amount of guarantees is USD 27,000 thousand which consists of USD 12,000 thousand of EWP (Barbados) 1 SRL’s contribution obligation and USD 15,000 thousand of SJEH’s portion (50%) of contribution obligation. (8) As of December 31, 2017, there is no financial guarantee contract provided by related parties. (9) Derivatives transactions with related parties as of December 31, 2017 are as follows: (i) Currency Swap In millions of won and thousands of U.S. dollars Counterparty Contract Contract Amount Contract interest rate per annum Contract exchange rate Pay Receive Pay (%) Receive (%) Korea Development Bank 2016~2019 ￦ 105,260 USD 100,000 2.48 % 2.38 % ￦ 1,052.60 2015~2025 111,190 USD 100,000 2.62 % 3.25 % 1,111.90 2017~2027 111,610 USD 100,000 2.31 % 3.13 % 1,116.10 2017~2020 114,580 USD 100,000 1.75 % 2.38 % 1,145.80 2016~2021 121,000 USD 100,000 2.15 % 2.50 % 1,210.00 2017~2022 113,300 USD 100,000 1.94 % 2.63 % 1,133.00 (ii) Currency forward In millions of won and thousands of foreign currencies Counterparty Contract Date Maturity date Contract amounts Contract exchange Pay Receive Korea Development Bank 2017.12.27 2021.07.12 ￦ 104,849 USD 100,000 ￦ 1,048.49 2017.12.14 2018.01.10 11,950 USD 11,000 1,086.35 2017.12.20 2018.01.16 15,130 USD 14,000 1,080.70 2017.12.28 2018.01.31 11,782 USD 11,000 1,071.10 (10) Salaries and other compensations to the key members of management of the Company for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In millions of won Salaries ￦ 1,271 1,463 1,271 Employee benefits 59 33 54 ￦ 1,330 1,496 1,325

Non-Cash Transactions

Non-Cash Transactions	12 Months Ended
	Dec. 31, 2017
Non-Cash Transactions [Abstract]
Non-Cash Transactions	48. Non-Cash Significant non-cash Transactions 2015 2016 2017 In millions of won Transfer from construction-in-progress ￦ 10,491,054 19,971,599 13,676,233 Recognition of asset retirement cost and related provision for decommissioning costs 699,673 470,941 2,494,802 Transfer from provision for disposal of spent nuclear fuel to accrued expenses 491,755 283,675 342,861

Commitments for Expenditure

Commitments for Expenditure	12 Months Ended
	Dec. 31, 2017
Commitments for Expenditure [Abstract]
Commitments for Expenditure	49. Commitments for Expenditure (1) The commitments for acquisition of property, plant and equipment as of December 31, 2016 and 2017 are as follows: 2016 2017 Contracts Amounts Balance Amounts Balance In millions of won Purchase of switch (25.8kV Eco) 11,395 ￦ 40,226 28,072 40,226 — Purchase of switch (25.8kV Eco) 12,450 — — 50,526 35,494 Purchase of cable (PVC,1C,2000SQ) 153,000M and others (Shin-Bupyung-Youngseo) 50,256 50,256 50,256 42,857 Purchase of cable (PVC, 1C, 2500SQ) 103,374M and others (Bukdangjin-Shintangjung) 42,500 42,500 42,500 29,987 Purchase of GIS (362KV 6300A 63KA) 23CB – YoungseoS/S — — 34,500 34,500 Purchase of GIS (362KV 6300A 63KA) 26CB – Shin-gosungS/S 36,950 19,897 36,950 — Purchase of GIS (362KV 6300A 63KA) 26CB – HwasungS/S — — 40,000 29,231 Purchase of GIS (362KV 6300A 63KA) 27CB – KwangyangS/S 37,476 27,760 37,476 18,044 Purchase of GIS (362KV 6300A 63KA) and 1 other 18CB – BukbusanS/S 34,000 20,766 34,000 — Purchase of GIS (800KV 8000A 50KA) 10CB – Shin-JungbuS/S 63,730 63,730 63,730 44,955 Purchase of transformer (765/345/23kV 666.7MVA, 2TANK) 6 units – Shin-JungbuS/S 37,500 37,500 37,500 37,500 Purchase of cable (TR CNCE-W/AL,1C,400SQ) 71,986 50,593 71,986 — Purchase of Concrete Poles (10M, 350KGF) 104,755 and 6 others 129,175 105,905 129,175 — Purchase of cable (TR CNCE-W/AL,1C,400SQ) — — 78,076 76,762 Purchase of Concrete Poles (10M, 350KGF) 121,900 and 6 others — — 133,387 112,981 Advanced E-Type — — 65,408 64,592 Purchase of Ground Switch (44-D-A125, — — 56,482 55,990 Construction of Shin-Kori units (#3,4) 6,856,150 — 7,363,514 93,637 Construction of Shin-Kori units (#5,6) 8,625,387 7,286,503 8,625,387 6,757,146 Construction of Shin-Hanwool units (#1,2) 7,982,342 1,157,700 7,982,342 1,015,813 Construction of Shin-Hanwool units (#3,4) 8,261,818 8,170,896 8,261,818 8,097,056 Construction of Yeosu thermal power units (#1) 174,291 1,139 174,291 — Other 27 contracts 430,204 222,555 262,400 114,041 Purchase of main machine for construction of Seoul Combined units (#1,2) 360,500 300,663 361,203 99,031 Construction of Seoul Combined units (#1,2) 225,205 129,589 227,685 60,568 Electricity construction of Shin-Boryeong units (#1,2) 354,740 26,878 379,115 — Purchase of smoke eliminating machine for construction of Shin-Boryeong units (#1,2) 121,093 2,023 169,544 36,417 Purchase of coal handling machine for construction of Shin-Boryeong units (#1,2) ￦ 146,353 3,543 146,353 — Service of designing Shin-Boryeong units (#1,2) 126,038 24,333 127,810 16,371 Purchase of main machine for construction of Shin-Boryeong units (#1,2) 851,132 10,746 866,065 4,981 Construction of Shin-Boryeong units (#1,2) 288,438 17,828 316,190 23,100 Purchase of furnace for construction of Shin-Seocheon thermal power plant — — 302,030 222,555 Purchase of turbine generator for construction of Shin-Seocheon thermal power plant — — 104,402 83,522 Electricity construction of Shin-Seocheon thermal power plant — — 200,453 196,993 Purchase of main machine for Jeju LNG combined — — 166,287 15,409 Purchase of coal handling machine for construction of Taean (#9,10) and IGCC units (conditional contract for installation) 192,945 38,218 193,375 5,129 Purchase of furnace for construction of Taean units (#9,10) 584,148 46,059 566,945 33,817 Service of designing Taean units (#9,10) 109,700 18,981 111,322 13,671 Purchase of desulfurization machine for construction of Taean units (#9,10) 92,086 1,017 — — Purchase of turbine generator for construction of Taean units (#9,10) 228,794 6,788 205,267 550 Purchase of combined generating machine for construction of Taean IGCC units 208,972 2,102 190,923 — Purchase of oxygen plant for construction of Taean IGCC units 98,979 221 94,564 199 Service of designing Taean IGCC plant units 44,802 3,342 44,802 2,669 Purchase of gasification plant for construction of Taean IGCC units 457,991 — 456,037 — Construction of Samcheok units (#1,2) 457,943 15,851 488,347 — Purchase of furnace for construction of Samcheok units (#1,2) 1,091,303 51,594 1,082,641 5,963 Purchase of coal handling machine for construction of Samcheok units (#1,2) 303,273 155 304,924 52,362 Service of designing Samcheok units (#1,2) 114,047 36,510 114,047 4,745 Purchase of main equipment 152,286 39,248 168,076 — Landscaping construction and other — — 63,110 — Construction of yard for Andong natural gas power plant 41,961 2,600 41,961 — Purchase of turbine main equipment for Samcheok units (#1,2) — — 215,333 874 Service of designing Dangjin units (#9,10) 122,426 6,125 122,426 — (2) As of December 31, 2017, details of contracts for inventory purchase commitment are as follows: The Company imports all of its uranium ore concentrates from sources outside Korea (including the United States, United Kingdom, Kazakhstan, France, Russia, South Africa, Canada and Australia) which are paid for with currencies other than Won, primarily in U.S. dollars. In order to ensure stable supply, the Company entered into long-term and medium-term contracts with various suppliers, and supplements such supplies with purchases of fuels on spot markets. The long-term and medium-term contract periods vary among contractors and the stages of fuel manufacturing process. Contract prices for processing of uranium are generally based on market prices. Contract periods for ore concentrates, conversion, enrichment and design and fabrication are as follows: Type Periods Contracted amounts Concentrate 2017 ~ 2030 39,662 Ton U3O8 Transformed 2017 ~ 2030 22,934 Ton U Enrichment 2017 ~ 2029 25,530 Ton SWU Molded 2017 ~ 2022 2,004 Ton U

Contingencies and Commitments

Contingencies and Commitments	12 Months Ended
	Dec. 31, 2017
Contingencies and Commitments [Abstract]
Contingencies and Commitments	50. Contingencies and Commitments (1) Ongoing litigations related with contingent liabilities and contingent assets as of December 31, 2016 and 2017 are as follows: 2016 2017 Number Claim Number Claim In millions of won As the defendant 675 ￦ 636,433 565 ￦ 477,719 As the plaintiff 193 489,605 185 690,934 As of December 31, 2017, among the litigations mentioned above, there are ongoing litigations of Korea Hydro & Nuclear Power Co., Ltd. (“KHNP”), a subsidiary of KEPCO, against KEPCO Engineering & Construction Company, Inc., a subsidiary of KEPCO, as a co-defendant A group of plaintiffs (consisting 2,167 individuals) filed a lawsuit against NSSC regarding NSSC’s approval on May 18, 2015 of extending the operation of Wolsong Unit 1 nuclear power plant. The appeal was ongoing as of December 31, 2017. Also, Greenpeace and others filed an administrative litigation against NSSC requesting cancelation of the construction permit of Shin-Kori Unit 5 and 6 it was ongoing as of December 31, 2017. The Company joined these litigations as a stakeholder with the permission of the Court. The book value of property, plant and equipment and provision for decommissioning costs of Wolsong Unit 1 nuclear power plant is ￦607,967 million and ￦642,015 million, respectively, as of December 31, 2017. If the continuance of operation of Wolsong Unit 1 nuclear power plant is annulled, significant losses may be incurred in connection with the property, plant and equipment of Wolsong Unit 1. In addition, the amount of provision may increase significantly, and the timing of actual cash outflows may be accelerated. The Company suspended the construction of Shin-Kori Unit 5 and 6 starting from July 24, 2017 to October 24, 2017, which is the public debate period regarding whether to continue the construction for Shin-Kori Unit 5 and 6, and is in the process of reviewing the appropriateness of the additional costs requested by the suppliers that occurred during that period. The Company believes that the possibility of economic outflow is probable and recognized ￦77,261 million of provision as described in note 26.(2). As of December 31, 2017, the Company has suspended the construction design of Shin-Hanwool Unit 3 and 4. The construction contract amount and the outstanding balance are described in note 49.(1), and the carrying amount of Shin-Hanwool Unit 3 and 4 is ￦ The Company is the defendant against a number of claims. The followings are potentially significant claims pertaining to the Company. ① Hyundai Engineering & Construction Co., Ltd.(“Hyundai E&C”), SK Engineering & Construction Co., Ltd. and GS Engineering & Construction Co., Ltd. filed a lawsuit for increase in contract bill (formerly, amounted to ￦1,000 million) against KHNP in September 2013, in relation to the design changes on the plant construction of Shin-Hanwool 1 & 2. Hyundai Engineering & Construction Co., Ltd. and two other companies increased the contract bill to ￦133,426 million in October 2014, ￦204,040 million in November 2015, and ￦204,564 million in January 2017, respectively, and submitted an application to demand extra contract payments due to the design changes. KHNP has paid ￦217,724 million of the claim amounts in full upon the first ruling in November 2016 and recognized the amount as addition to construction-in-progress ② In December 2013, the Supreme Court of Korea ruled that regular bonuses also fall under the category of ordinary wages on the condition that those bonuses are paid regularly and uniformly. Also, the Supreme Court ruled that employees are entitled to retroactively demand certain wages based on the new ordinary wages that include regular bonuses as additional wages. However, the request may be limited to the extent of the principle of good faith. The Company believes that the possibility of economic outflow is probable on the ongoing and the expected lawsuit. For this reason, the Company recognized ￦56,052 million of other provision in relation to the lawsuit as of December 31, 2017. Except these significant ongoing claims, there are 10 arbitration cases pertaining to the Company as of December 31, 2017 and the significant arbitration cases are as follows: ① KEPCO and KEPCO KDN Co., Ltd., a subsidiary of KEPCO, have been accused of breach of contract in relation to ERP software, which is provided by SAP Korea Ltd. The litigation was filed in the International Chamber of Commerce International Court of Arbitration but the Company has not recognized any provision because the probability of economic benefit outflow is remote and the related amount cannot be reliably estimated. ② Hyundai Samsung Joint Venture (HSJV), one of the subcontractors of the Company, filed an arbitration against the Company at the London Court of International Arbitration (LCIA) in 2016 due to disagreements in UAE nuclear power plant construction project, but the Company has not recognized any losses because the probability of economic benefit outflow is remote and the related amount cannot be reasonably estimated. ③ In prior years, Hyundai E&C, GS Engineering & Construction Corp., and Hansol SeenTec Co., Ltd. filed on arbitration against the Company to the Korea Commercial Arbitration Board in relation to the request for additional construction costs but the Company has not recognized any provision because the probability of economic benefit outflow is remote and the related amount cannot be reliably estimated. ④ In prior years, Halla Corporation filed on arbitration against the Company to the Korea Commercial Arbitration Board in relation to the request for additional construction costs and the Company filed on arbitration against Halla Corporation to the Korea Commercial Arbitration Board in relation to the request for a penalty payment for the delayed construction work. The Company has recognized ￦4,916 million of provision for the best estimate of the expenditure required to fulfill its obligations in relation to this arbitration as of December 31, 2017. (2) Guarantees of borrowings provided to other companies as of December 31, 2016 and 2017 are as follows: ① In order to secure its status as a shareholder of Navanakorn Electric Co., Ltd., the Company has signed a fund supplement contract. According to the contract, in case Navanakorn Electric Co., Ltd. does not have sufficient funds for its operation or repayment of borrowings, the Company bears a payment obligation in proportion to its ownership. ② The Company has outstanding borrowings with a limit of USD 275,600 thousand from its creditors such as International Finance Corporation. Regarding the borrowing contract, the Company has guaranteed capital contribution of USD 69,808 thousand and additional contribution up to USD 19,000 thousand for contingencies, if any. Moreover, for one of the electricity purchasers, Central Power Purchasing Agency Guarantee Ltd., the Company has provided payment guarantee up to USD 2,777 thousand, in case of construction delay or insufficient contract volume after commencement of the construction. ③ The Company has provided PT. Perusahaan Listrik Negara performance guarantee up to USD 2,293 thousand and Mizuho bank and others investment guarantee up to USD 43,500 thousand in proportion to its ownership in the electricity purchase contract with PT. Cirebon Energi Prasarana in relation to the second electric power generation business in Cirebon, Indonesia. ④ The Company has provided the Bank of Tokyo Mitsubishi UFJ (BTMU) borrowing guarantee up to USD 41,258 thousand in proportion to its ownership in the equity bridge loan guarantee with PT. Cirebon Energi Prasarana in relation to the second electric power generation business in Cirebon, Indonesia. ⑤ The Company has provided the Export-Import Bank of Korea, BNP Paribas and ING Bank guarantee of mutual investment of USD 2,440 thousand, which is equivalent to the ownership interest of PT BS Energy and PT Nusantara Hydro Alam, in order to guarantee the expenses related to hydroelectric power business of Tanggamus, Indonesia. ⑥ The Company has provided the Export-Import Bank of Korea and SMBC guarantee of mutual investment of USD 401 thousand, which is equivalent to the ownership interest of PT Mega Power Mandiri, in order to guarantee the expenses related to hydroelectric power business of PT Wampu Electric Power, an associate of the Company. ⑦ The Company has provided Samsung C&T Corporation bidding guarantee up to USD 793 thousand to participate in the bidding of the Sri Lanka combined cycle project. (3) Credit lines provided by financial institutions as of December 31, 2017 are as follows: Commitments Financial institutions Currency Limited amount Exercised amount In millions of won and thousands of foreign Commitments on bank-overdraft Nonghyup Bank and others KRW 1,555,000 68,859 Commitments on bank-daylight overdraft Nonghyup Bank KRW 280,000 — Limit amount available for CP Shinhan Bank and others KRW 1,100,000 — Limit amount available for card KEB Hana Bank and others KRW 46,733 2,775 Banco de Oro PHP 5,000 5,000 Loan limit Kookmin Bank and others KRW 895,500 425,411 BNP Paribas and others USD 1,910,700 20,000 Certification of payment on L/C Woori Bank and others USD 1,029,604 233,166 Certification of performance guarantee on contract KEB Hana Bank EUR 1,958 1,958 KEB Hana Bank and others INR 230,515 230,515 Korea Development Bank and others JPY 620,000 620,000 Seoul Guarantee Insurance and others KRW 104,248 104,248 Bank of Kathmandu NPR 32,633 32,633 KEB Hana Bank SAR 102,186 87,991 Standard Chartered and others USD 753,652 696,806 KEB Hana Bank CAD 168 168 Certification of bidding SMBC and others USD 60,000 10,230 ABSA and others ZAR 55,730 55,730 Advance payment bond, Warranty bond, Retention bond and others KEB Hana Bank INR 157,830 157,830 Export-Import Bank of Korea and others USD 3,850,534 753,025 Others Nonghyup Bank and others KRW 451,521 15,037 KEB Hana Bank and others USD 1,063,670 758,536 Inclusive credit Shinhan Bank INR 47,489 47,489 KEB Hana Bank KRW 258,000 117,398 Shinhan Bank and others USD 32,125 16,155 Trade finance BNP Paribas and others USD 800,000 — (4) As of December 31, 2017, the blank check and assets provided as collaterals or pledges to financial institutions by the Company are follows: Guarantor Guarantee Type of guarantee Currency Amount Description In millions of won and thousands of foreign currencies Korea East-West Power Co., Ltd. Korea Development Bank and others Shareholdings of Gyeongju Wind Power Co., Ltd. KRW 15,958 Collateral for borrowings Korea Midland Power Co.,Ltd. IBK and others Shareholdings of Commerce and Industry Energy Co., Ltd. KRW 13,605 Collateral for borrowings Korea Southern Power Co., Ltd. Shinhan Bank and others Shareholdings of KOSPO Youngnam Power Co., Ltd. KRW 40,000 Collateral for borrowings Korea South-East Power Co., Ltd. International Finance Corporation and others Shareholdings of Mira Power Limited KRW 44,192 Collateral for borrowings Korea Hydro & Nuclear Power Co., Ltd. Korea Development Bank and others Shareholdings of Gyeonggi Green Energy Co., Ltd. KRW 47,000 Collateral for borrowings Gyeonggi Green Energy Co., Ltd. Korea Development Bank and others Factory estate and others KRW 327,080 Collateral for borrowings (*) Commerce and Industry Energy Co., Ltd. IBK and others Land, buildings, structures and machinery and others Cash and cash equivalents KRW KRW 110,500 11,642 Collateral for borrowings Gyeongju Wind Power Co., Ltd. SK Securities Co., Ltd. and others Property, plant and equipment and others KRW 97,980 Collateral for borrowings Existing or expected trade receivables KRW 4,800 Cash and cash equivalents KRW 8,769 KOSPO Youngnam Power Co., Ltd. Shinhan Bank and others Bank deposit and insurance claim KRW 396,120 Collateral for borrowings Qatrana Electric Power Company The Islamic Development Bank and others Finance Lease receivable and property, plant and equipment and others JOD 188,580 Collateral for borrowings KST Electric Power Company Scotiabank Inverlat, S.A Finance Lease receivable and others USD 289,026 Collateral for borrowings (*) The Company was provided with shares of Gyeonggi Green Energy Co., Ltd., one of its subsidiaries, from the investors as collateral related to long-term borrowings. Additionally, pledge for shares, pledge for transfer of rights of long-term borrowings, pledge for insurance claims and other pledges were established. The Company has ￦1,197 million of project loans from Korea Resource Corporation as of December 31, 2017. The Company has provided a blank check as repayment guarantee. (5) The Company temporarily suspended operations of the Gangneung hydroelectric generating plant, with a carrying amount of ￦88,447 million as of December 31, 2017, to improve the quality of water used in generating electricity. The expenses related to the suspension of operations of ￦137 million and depreciation on the utility plant of ￦6,644 million are recorded in other expenses for the year ended December 31, 2017. (6) Due to the Korean government’s announcement of suspension of operation in the Gaeseong Industrial District, it is uncertain if the Company can exercise the property rights for the Company’s facility in the Gaeseong Industrial District as of December 31, 2017. The book value of facility is ￦18,724 million and the amount of trade receivables related to the companies residing in Gaeseong industrial complex is ￦2,911 million. The Company has entered into an insurance agreement covering up to ￦7,000 million with the Export-Import Bank of Korea related to Gaeseong industrial complex. The ultimate outcome of this event cannot be reasonably estimated.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	51. Subsequent Events (1) Subsequent to December 31, 2017, Korea Hydro & Nuclear Power Co., Ltd., Korea South-East Power Co., Ltd., Korea Midland Power Co., Ltd. and Korea Southern Power Co., Ltd. issued additional corporate bond, asset backed short-term bond, non-guaranteed Company Name Type Issue date Maturity Interest rate (%) Amounts In millions of won and thousands of foreign currencies Korea Hydro & Nuclear Power Co., Ltd. #48-1 2018.03.13 2021.03.13 2.40 ￦ 160,000 #48-2 2018.03.13 2023.03.13 2.70 20,000 #48-3 2018.03.13 2028.03.13 2.86 30,000 #48-4 2018.03.13 2048.03.13 2.94 90,000 Global bond 9 2018.03.13 2028.03.13 3.35 HKD 1,650,000 Korea South-East Power Co., Ltd Asset backed short-term bond 2018.01.24 2018.04.10 1.79 190,000 Korea Midland Power Co., Ltd #41-1 non-guaranteed corporate bond 2018.02.20 2023.02.20 2.72 60,000 #41-2 non-guaranteed corporate bond 2018.02.20 2028.02.20 2.92 130,000 Korea Southern Power Co., Ltd #43-1 non-guaranteed bond 2018.01.11 2021.01.11 2.32 120,000 #43-2 non-guaranteed bond 2018.01.11 2023.01.11 2.57 20,000 #43-3 non-guaranteed bond 2018.01.11 2028.01.11 2.76 60,000 Non-guaranteed foreign currency bond (Global bond 18) 2018.01.29 2021.01.29 3.00 USD 400,000 (2) In January 2018, the Company sold all of its shares in KODE NOVUS II LLC and other investors in the joint venture sold all of their shares in KODE NOVUS I LLC and KODE NOVUS II LLC. In accordance with the agreement between the shareholders and the creditors of KODE NOVUS I LLC and KODE NOVUS II LLC, the Company’s right to indemnity and supplemental funding obligations to the investors and creditors have been eliminated. Accordingly, the Company reversed the entire amount of the provisions for the right to indemnity.

Basis of Preparation (Policies)

Basis of Preparation (Policies)	12 Months Ended
	Dec. 31, 2017
Basis of Preparation [Abstract]
Statement of compliance	These consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”).
Basis of measurement	Basis of measurement These consolidated financial statements have been prepared on the historical cost basis, except for the following material items in the consolidated statements of financial position: • derivative financial instruments are measured at fair value • available-for-sale • liabilities for defined benefit plans are recognized at the net of the total present value of defined benefit obligations less the fair value of plan assets
Functional and presentation currency	Functional and presentation currency These consolidated financial statements are presented in Korean won (“Won”), which is KEPCO’s functional and presentation currency.
Use of estimates and judgments	The preparation of the consolidated financial statements in conformity with IFRS requires management to make judgments, estimates and assumptions that affect the application of accounting policies and the reported amounts of assets, liabilities, income and expenses. Actual results may differ from these estimates. Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimates are revised and in any future periods affected. The following are the key assumptions concerning the future, and other key sources of estimation uncertainty at the end of the reporting period, that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year. (i) Unbilled revenue Energy delivered but not metered nor billed are calculated at the reporting date and is estimated based on consumption statistics and selling price estimates. Determination of the unbilled revenues at the end of the reporting period is sensitive to the estimated consumptions and prices based on statistics. Unbilled revenue recognized for the years ended December 31, 2016 and 2017 are ￦1,615,322 million and ￦1,672,385 million, respectively. (ii) Continuing operation of Wolsong Unit 1 nuclear power plant Wolsong Unit 1 nuclear power plant of the Company commenced operations on November 21, 1982 and its 30-year According to the Eighth Basic Plan for Electricity Supply and Demand by the Ministry of Trade, Industry and Energy, Wolsong Unit 1 nuclear power plant is expected to go through a comprehensive evaluation for the feasibility of continuous operation including economic efficiency and acceptability of household and community in 2018. The Korean government plans to refund to the Company for reasonable expenditures incurred in relation to the phase-out Information about critical judgments in applying accounting policies that have the most significant effect on the amounts recognized in the consolidated financial statements is included in the following notes: • Note 17 – Investments in Associates and Joint Ventures • Note 18 – Property, Plant and Equipment • Note 20 – Construction Services Contracts • Note 45 – Risk Management Information about assumptions and estimation uncertainties that have a significant risk of resulting in a material adjustment within the next financial year is included in the following notes: • Note 41 – Income Taxes • Note 25 – Employment Benefits
Changes in accounting policies	(i) Amendments to to IAS 7 ‘Statement of Cash Flows’ The Company has adopted amendments to IAS ‘Statement of Cash Flows’ since January 1, 2017. The amendments require changes in liabilities arising from financing activities to be disclosed. The amendments are not required to provide comparative information for prior periods when applying for the first time. Information about changes in liabilities arising from financing activities is included in note 23 and note 24. (ii) Amendments to IAS 12 ‘Income Taxes’ The Company has adopted amendments to IAS 12 ‘Income Taxes’ since January 2017. The amendments clarify that unrealized losses on fixed-rate debt instruments measured at fair value and measured at cost for tax purposes give rise to a deductible temporary difference regardless of whether the holder expects to recover the carrying amount of the debt instrument by sale or by use and that the estimate of probable future taxable profit may include the recovery of some of assets for more than their carrying amount. When the Company assesses whether there will be sufficient taxable profit, the Company should compare the deductible temporary differences with future taxable profit that excludes tax deductions resulting from the reversal of those deductible temporary differences. The Company believes that there is no significant impact on the Company’s consolidated financial statements and did not retroactively restate the comparative consolidated financial statements for the prior period.
New standards and amendments not yet adopted	New standards and amendments not yet adopted The following new standards, including IFRS 9 ‘Financial Instruments’ and IFRS 15 ‘Revenue from Contracts with Customers’, interpretations and amendments to existing standards have been published but are not mandatory for the Company for annual periods beginning on January 1, 2017, and the Company has not early adopted them. The Company will apply IFRS 9 ‘Financial Instruments’ and IFRS 15 ‘Revenue from Contracts with Customers’ for annual periods beginning on January 1, 2018. The Company has conducted a detailed assessment on adoption of these standards and based on the circumstance and information available when these financial statements were authorized for issuance. (i) IFRS 9 ‘Financial Instruments’ IFRS 9 sets out the requirements for recognizing and measuring financial assets, financial liabilities and certain contracts to buy or sell non-financial The Company will apply the exemption allowing it not to restate the comparative information for prior periods upon adoption of IFRS 9. The Company will retroactively apply the cumulative effect of the adoption of IFRS 9 in retained earnings as of the date of initial application (January 1, 2018). Expected impacts on the consolidated financial statements are categorized as follows: ① Classification and measurement of financial assets IFRS 9 includes a new classification and measurement of financial assets that reflects the business model in which assets are managed and their cash flow characteristics. Under IFRS 9, financial assets are classified into three principal categories; measured at amortized cost, fair value through other comprehensive income (FVOCI) and fair value through profit or loss (FVTPL) based on the business model in which assets are managed and their cash flow characteristics. Under IFRS 9, derivatives embedded in hybrid contracts where the host is a financial asset are not bifurcated. Instead, the hybrid financial instrument as a whole is assessed for classification. The criteria for classification and measurement of financial assets under IFRS 9 are as follows: • A financial asset is measured at amortized cost if it meets both of the following conditions and is not designated as at FVTPL: 1) the asset is held within a business model whose objective is to hold assets to collect contractual cash flows; and 2) the contractual terms of the financial asset give rise on specified dates to cash flows that are solely payments of principal and interest on the principal amount outstanding. • A financial asset is measured at FVOCI if it meets both of the following conditions and is not designated as at FVTPL: 1) the asset is held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets; and 2) the contractual terms of the financial asset give rise on specified dates to cash flow that are solely payments of principal and interest on the principal amount outstanding. On initial recognition of equity investment that is not held for trading, the Company may irrevocably elect to present subsequent changes in fair value in OCI, and will not reclassify(recycle) the those items in OCI to profit or loss subsequently. • A financial asset is measured at FVTPL if the contractual terms of the financial asset give rise to specified dates to cash flows that are not solely payments of principal and interest on the principal amount outstanding, the debt instrument is held within a business model whose objective is to sell the asset, or the equity instruments that are not elected to be designated as measured at FVOCI. As of December 31, 2017, the Company has financial assets at fair value through profit or loss amounting to ￦133,532 million, available-for-sale held-to-maturity Based on the result of the detailed assessment to date, the expected impacts on the Company’s financial assets (excluding derivative instruments) on the date of initial application (January 1, 2018) are as follows: Classification based on IAS 39 Classification based on IFRS 9 Amount based Amount based In millions of won Financial assets at FVTPL FVTPL ￦ 111,512 111,512 Loans and receivables Amortized cost 15,203,663 14,412,339 Loans and receivables FVTPL — 791,324 Available-for-sale FVOCI 699,833 476,941 Available-for-sale FVTPL — 222,892 Held-to-maturity Amortized cost 3,144 3,144 Total financial assets (excluding derivative instruments) ￦ 16,018,152 16,018,152 Upon adoption of IFRS 9, ￦791,324 million of loans and receivables and ￦222,892 million of available-for-sale available-for-sale ② Classification and measurement of financial liabilities Under IFRS 9, the amount of change in the fair value attributable to the changes in the credit risk of the financial liabilities is presented in OCI, not recognized in profit or loss, and the OCI amount will not be reclassified (recycled) to profit or loss. However, if doing so creates or increase an accounting mismatch, the amount of change in the fair value is recognized in profit or loss. The Company did not elect to designate financial liabilities as FVTPL and believes that there is no significant impact on the Company’s consolidated financial statements upon adoption of IFRS 9. ③ Impairment: Financial assets and contract assets IFRS 9 replaces the ‘incurred loss’ model in the existing standard with a forward-looking ‘expected credit loss’ (ECL) model for debt instruments, lease receivables, contractual assets, loan commitments, financial guarantee contracts. Under IFRS 9, impairment losses are likely to be recognized earlier than using the incurred loss model under the existing guidance in IAS 39 as loss allowances will be measured on either of the 12-month Classification Loss allowances Stage 1 Credit risk has not increased significantly since the initial recognition 12-month ECL: ECLs that resulted from possible default events within the 12 months after the reporting date Stage 2 Credit risk has increased significantly since the initial recognition Lifetime ECL: ECL that resulted from all possible default events over the expected life of a financial instrument Stage 3 Credit-impaired Under IFRS 9, an entity shall always measure the loss allowance at an amount equal to lifetime expected credit losses for trade receivables or contract assets that result from transactions that are within the scope of IFRS 15 and that do not contain a significant financing component in accordance with IFRS 15 and if the trade receivables or contract assets include a significant financing component, an entity may choose as its accounting policy to measure the loss allowance at an amount equal to lifetime expected credit losses. As of December 31, 2017, the Company has debt instruments in financial assets measured at amortized cost amounting to ￦15,464,202 million (loans and receivables) and has recognized loss allowances of ￦260,539 million. Under adoption of IFRS 9, the Company plans to elect to measure the loss allowance at an amount equal to lifetime expected credit losses for trade receivables, contract assets and lease receivables that include a significant financing component. Based on the result of the detailed assessment to date, the expected impacts on the Company’s loss allowances on the date of initial application (January 1, 2018) are as follows: Type Amount based on IAS 39 (A) Amount based on IFRS 9 (B) Increase (decrease) (B-A) In millions of won Trade and other receivables ￦ 251,591 258,360 6,769 Other financial assets 8,948 8,948 — Total ￦ 260,539 267,308 6,769 ④ Hedge accounting When initially applying IFRS 9, an entity may elect as its accounting policy to continue to apply the hedge accounting requirements of IAS 39. The Company plans to elect to continue apply the hedge accounting requirements of IAS 39. As of December 31, 2017, the Company has asset and liabilities designated as hedged items amounting to ￦10,606 million and ￦277,130 million, respectively. (ii) IFRS 15 ‘Revenue from Contracts with Customers’ IFRS 15 sets out a comprehensive framework for determining whether revenue is recognized, the extent of revenue recognized, and when revenue is recognized. It replaces existing revenue recognition guidance, including IAS 18 ‘Revenue’, IAS 11 ‘Construction Contracts’, SIC-31 The Company will retrospectively apply and recognize the cumulative effect of the adoption of IFRS 15 at the date of initial application (January 1, 2018) and has determined to retrospectively apply to only those contracts that were not completed as of the date of initial application (January 1, 2018). Accordingly, the Company will not restate the comparative periods. Existing IFRS standards and interpretations including IAS 18 provide revenue recognition guidance by transaction types such as sales of goods, rendering of services, interest income, royalty income, dividend income and construction revenue; however, under the new standard, IFRS 15, the five-step approach (Step 1: Identify the contract(s) with a customer, Step 2: Identify the performance obligations in the contract, Step 3: Determine the transaction price, Step 4: Allocate the transaction price to the performance obligations in the contract, Step 5: Recognize revenue when the entity satisfied a performance obligation) is applied for all types of contracts or agreements. Expected impacts on the consolidated financial statements are categorized as follows: ① Identify the performance obligations in the contract The Company is engaged in the generation, transmission and distribution of electricity and development of electric power resources, and electricity sales revenue accounts for 91.3% of consolidated revenue for the year ended December 31, 2017. Under IFRS 15, supplying electricity is a series of distinct goods or services identified as a single performance obligation. The Company is also engaged in contracts with customers for transmission and distribution, provision of power generation byproducts, EPC business, O&M, etc. that are identified as different performance obligations for each contract. Based on the result of the detailed assessment to date, the Company believes that the impact of identifying separate the performance obligations in the contract on the Company’s revenue is not significant. ② Variable consideration The Company may be subject to a variation of consideration paid by the customer due to the progressive electricity billing system, discounts on electricity bills for policy purposes, penalties and delinquent payment, etc. In applying IFRS 15, the Company estimates an amount of variable consideration by using the expected value method that the Company expects to better predict the amount of consideration to which it will be entitled, and includes in the transaction price some or all of an amount of variable consideration only to the extent that it is highly probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Based on the result of the detailed assessment to date, the Company believes that the impact of variable consideration on the Company’s revenue is not significant. ③ Performance obligations satisfied over time The Company provides its customers with services such as EPC business, O&M, etc. over time. The Company recognizes revenues based on the percentage-of-completion Under IFRS 15, an entity recognizes revenue over time if one of the following criteria is met: (a) the customer simultaneously receives and consumes the benefits provided by the entity’s performance as the entity performs; (b) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced; or (c) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. Based on the result of the detailed assessment to date, the impact of the revenue recognition over time based on the percentage-of-completion (iii) IFRS 16 ‘Leases’ IFRS 16 replaces IAS 17 ‘Leases’, and IFRIC 4 ‘Determining whether an Arrangement contains a Lease’. This standard is effective for annual reporting periods beginning on or after January 1, 2019, with early adoption permitted if IFRS 15 ‘Revenue from Contracts with Customers’ has also been applied. Under IFRS 16, a lessee shall apply this standard to its leases either: (a) retrospectively to each prior reporting period presented applying IAS 8 ‘Accounting Policies, Changes in Accounting Estimates and Errors’; or (b) retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application. The Company has not yet determined the transition approach for IFRS 16. IFRS 16 provides a single lessee accounting model in which the lessee recognizes lease related assets and liabilities in the statement of financial position. A lessee is required to recognize a right-of-use Upon adoption of IFRS 16, the nature of the costs associated with the lease will change as the operating lease payments recognized based on a straight-line basis will change to depreciation expense of a right-of-use The Company plans to conduct a detailed assessment of the potential impact from the application of IFRS 16 during the year ending December 31, 2018. (iv) IFRIC 22 ‘Foreign Currency Transactions and Advance Consideration’ IFRIC 22, published on December 8, 2016, clarifies the date of the transaction for the purpose of determining the exchange rate to use on initial recognition of the related asset, expense or income, when an entity has received or paid advance consideration in a foreign currency. IFRIC 22 is effective for annual reporting periods beginning on or after January 1, 2018, with earlier adoption permitted. The Company is currently performing a detailed assessment of the impact resulting from the application of IFRIC 22 and plans to complete the assessment in advance of its effective date. (v) Amendments to IAS 40 ‘Investment Property’ The amendments clarify when an entity should transfer a property asset to, or from, investment property. The amendments are effective for annual periods beginning on or after January 1, 2018, with earlier adoption permitted. The Company is currently performing a detailed assessment of the impact resulting from the application of amendments to IAS 40 and plans to complete the assessment in advance of its effective date.

Significant Accounting Polici58

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Basis of consolidation	The consolidated financial statements are the financial statements of a group in which the assets, liabilities, equity, income, expenses and cash flows of the parent and its subsidiaries are presented as those of a single economic entity. Subsidiaries are controlled by the Company. The Company controls an entity when it is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Income and expense of a subsidiary acquired or disposed of during the year are included in the consolidated statement of comprehensive income from the effective date of acquisition and up to the effective date of disposal, as appropriate. Total comprehensive income of subsidiaries is attributed to the owners of the Company and to the non-controlling non-controlling When necessary, adjustments are made to the financial statements of subsidiaries to bring their accounting policies into line with those of the Company. Transactions within the Company are eliminated during the consolidation. Changes in the Company’s ownership interests in a subsidiary that do not result in the Company losing control over the subsidiary are accounted for as equity transactions. The carrying amounts of the Company’s interests and the non-controlling non-controlling When the Company loses control of a subsidiary, the income or loss on disposal is calculated as the difference between (i) the aggregate of the fair value of the consideration received and the fair value of any retained interest and (ii) the previous carrying amount of the assets (including goodwill), and liabilities of the subsidiary and any non-controlling
Business combinations	Business combinations A business combination is accounted for by applying the acquisition method, unless it is a combination involving entities or businesses under common control. The consideration transferred in a business combination is measured at fair value, which is calculated as the sum of the acquisition-date fair values of the assets transferred by the Company, liabilities incurred by the Company to the former owners of the acquiree and the equity interests issued by the Company in exchange for control of the acquiree. Acquisition-related costs are generally recognized in income or loss as incurred. At the acquisition date, the identifiable assets acquired and the liabilities assumed are recognized at their fair value at the acquisition date, except that: • deferred tax assets or liabilities and liabilities or assets related to employee benefit arrangements are recognized and measured in accordance with IAS 12 ‘ Income Taxes’ and IAS 19 ‘ Employee Benefits’ respectively; • assets (or disposal groups) that are classified as held for sale in accordance with IFRS 5 ‘Non-current Goodwill is measured as the excess of the sum of the consideration transferred, the amount of any non-controlling non-controlling Non-controlling non-controlling transaction-by-transaction non-controlling The subsequent accounting for changes in the fair value of the contingent consideration that do not qualify as measurement period adjustments depends on how the contingent consideration is classified. Contingent consideration that is classified as equity is not re-measured re-measured When a business combination is achieved in stages, the Company’s previously held equity interest in the acquiree is re-measured If the initial accounting for a business combination is incomplete by the end of the reporting period in which the combination occurs, the Company reports provisional amounts for the items for which the accounting is incomplete. Those provisional amounts are adjusted during the measurement period (see above), or additional assets or liabilities are recognized, to reflect new information obtained about facts and circumstances that existed at the acquisition date that, if known, would have affected the amounts recognized at that date. The assets and liabilities acquired under business combinations under common control are recognized at the carrying amounts recognized previously in the consolidated financial statements of the ultimate parent. The difference between consideration transferred and carrying amounts of net assets acquired is recognized as part of share premium.
Investments in associates	An associate is an entity over which the Company has significant influence and that is neither a subsidiary nor an interest in a joint venture. Significant influence is the power to participate in the financial and operating policy decisions of the investee but does not control or joint control over those policies. The results and assets and liabilities of associates are incorporated in these consolidated financial statements using the equity method of accounting. If the investment is classified as held for sale, in which case it is accounted for in accordance with IFRS 5 ‘Non-current After the disposal takes place, the Company shall account for any retained interest in associates in accordance with IAS 39 ‘Financial Instruments: Recognition and Measurement’ unless the retained interest continues to be an associates, in which case the entity uses the equity method. Under the equity method, an investment in an associate is initially recognized in the consolidated statement of financial position at cost and adjusted thereafter to recognize the Company’s share of the income or loss and other comprehensive income of the associate. When the Company’s share of losses of an associate exceeds the Company’s interest in that associate (which includes any long-term interests that, in substance, form part of the Company’s net investment in the associate), the Company discontinues recognizing its share of further losses. Additional losses are recognized only to the extent that the Company has incurred legal or constructive obligations or made payments on behalf of the associate. Any excess of the cost of acquisition over the Company’s share of the net fair value of the identifiable assets, liabilities and contingent liabilities of an associate recognized at the date of acquisition is recognized as goodwill, which is included within the carrying amount of the investment. Any excess of the Company’s share of the net fair value of the identifiable assets, liabilities and contingent liabilities over the cost of acquisition, after reassessment, is recognized immediately in income or loss. The requirements of IAS 39 ’Financial Instruments: Recognition and Measurement’, are applied to determine whether it is necessary to recognize any impairment loss with respect to the Company’s investment in an associate. When necessary, the entire carrying amount of the investment (including goodwill) is tested for impairment in accordance with IAS 36 ‘Impairment of Assets’ as a single asset by comparing its recoverable amount (higher of value in use and fair value less costs to sell) with its carrying amount, any impairment loss recognized forms part of the carrying amount of the investment. Any reversal of that impairment loss is recognized in accordance with IAS 36 to the extent that the recoverable amount of the investment subsequently increases. Upon disposal of an associate that results in the Company losing significant influence over that associate, any retained investment is measured at fair value at that date and the fair value is regarded as its fair value on initial recognition as a financial asset in accordance with IAS 39. The difference between the previous carrying amount of the associate attributable to the retained interest and its fair value is included in the determination of the gain or loss on disposal of the associate. In addition, the Company accounts for all amounts previously recognized in other comprehensive income in relation to that associate on the same basis as would be required if that associate had directly disposed of the related assets or liabilities. Therefore, if a gain or loss previously recognized in other comprehensive income by that associate would be reclassified to income or loss on the disposal of the related assets or liabilities, the Company reclassifies the gain or loss from equity to income or loss (as a reclassification adjustment) when it loses significant influence over that associate. When the Company transacts with its associate, incomes and losses resulting from the transactions with the associate are recognized in the Company’s consolidated financial statements only to the extent of interests in the associate that are not related to the Company.
Joint arrangements	Joint arrangements A joint arrangement is an arrangement of which two or more parties have joint control. Joint control is the contractually agreed sharing of control of an arrangement, which exists only when decisions about the relevant activities require the unanimous consent of the parties sharing control. Joint arrangements are classified into two types—joint operations and joint ventures. A joint operation is a joint arrangement whereby the parties that have joint control of the arrangement (i.e. joint operators) have rights to the assets, and obligations for the liabilities, relating to the arrangement. A joint venture is a joint arrangement whereby the parties that have joint control of the arrangement (i.e. joint ventures) have rights to the net assets of the arrangement. If the Company is a joint operator, the Company is to recognize and measure the assets and liabilities (and recognize the related revenues and expenses) in relation to its interest in the arrangement in accordance with relevant IFRSs applicable to the particular assets, liabilities, revenues and expenses. If the joint arrangement is a joint venture, the Company is to account for that investment using the equity method accounting in accordance with IAS 28 ‘Investment in Associates and Joint Ventures’ (refer to note 3.(3)), except when the Company is applicable to the IFRS 5 ‘Non-current
Non-current assets held for sale	Non-current Non-current non-current When the Company is committed to a sale plan involving loss of control of a subsidiary, all of the assets and liabilities of that subsidiary are classified as held for sale when the criteria described above are met, regardless of whether the Company will retain a non-controlling Non-current
Goodwill	Goodwill The Company measures goodwill which acquired in a business combination at the amount recognized at the date on which it obtains control of the acquiree (acquisition date) less any accumulated impairment losses. Goodwill acquired in a business combination is allocated to each CGU that is expected to benefit from the synergies arising from the business acquired. The Company assesses at the end of each reporting period and whenever there is an indication that the asset may be impaired. An impairment loss is recognized if the carrying amount of an asset or a CGU exceeds its recoverable amount. Impairment losses are recognized in profit or loss. Any impairment identified at the CGU level will first reduce the carrying value of goodwill and then be used to reduce the carrying amount of the other assets in the CGU on a pro rata basis. Except for impairment losses in respect of goodwill which are never reversed, an impairment loss is reversed if there has been a change in the estimates used to determine the recoverable amount. An impairment loss is reversed only to the extent that the asset’s carrying amount does not exceed the carrying amount that would have been determined, net of depreciation or amortization, if no impairment loss had been recognized.
Revenue recognition	Revenue from the sale of goods, rendering of services or use of the Company assets is measured at the fair value of the consideration received or receivable, net of returns, trade discounts and volume rebates, which are recognized as a reduction of revenue. Revenue is recognized when the amount of revenue can be measured reliably and it is probable that the economic benefits associated with the transaction will flow to the Company. (i) Sales of goods The Korean government approves the utility rates charged to customers by the Company’s power transmission and distribution division. The Company’s utility rates are designed to recover the Company’s reasonable costs plus a fair investment return. The Company recognize revenue from electricity sales revenue based on power sold (transferred to the customer) up to the reporting date and the corresponding utility rate charged to customers. To determine the amount of power sold, the Company estimates daily power volumes of electricity for residential, commercial, general, etc. The differences between the current month’s estimated amount and actual (meter-read) amount, is adjusted for (trued-up) (ii) Sales of services Revenue from services rendered is recognized in profit or loss in proportion to the stage of completion of the transaction at the reporting date. The stage of completion is assessed by reference to surveys of work performed or services performed to date as a percentage of total services to be performed or the proportion that costs incurred to date bear to the estimated total costs of the transaction or other methods that reliably measures the services performed. (iii) Dividend income and interest income Dividend income is recognized in profit or loss on the date that the Company’s right to receive payment is established, which in the case of quoted securities is the ex-dividend Interest income is recognized as it accrues in profit or loss, using the effective interest method. Interest income is accrued on a time basis, by reference to the principal outstanding and at the effective interest rate applicable, which is the rate that exactly discounts estimated future cash receipts through the expected life of the financial asset to that asset’s net carrying amount on initial recognition. (iv) Rental income The Company’s policy for recognition of revenue from operating leases is described in note 3.(9) below.
Construction services revenue	The Company provides services related to the construction of power plants related to facilities of its customers, mostly in foreign countries. When the outcome of a construction contract can be estimated reliably, revenue and costs are recognized based on the stage of completion of the contract activity at the end of the reporting period, measured based on the proportion of contract costs incurred for work performed to date relative to the estimated total contract costs, except where this would not be representative of the stage of completion. Variations in contract work, claims and incentive payments are included to the extent that the amount can be measured reliably and its receipt is considered probable. When the outcome of a construction contract cannot be estimated reliably, contract revenue is recognized to the extent of contract costs incurred when it is probable the revenue will be realized. Contract costs are recognized as expenses in the period in which they are incurred. When it is probable that total contract costs will exceed total contract revenue, the expected loss is recognized as an expense immediately. When contract costs incurred to date plus recognized income less recognized losses exceed progress billings, the surplus is presented as amounts due from customers for contract work. For contracts where progress billings exceed contract costs incurred to date plus recognized income less recognized losses, the surplus is presented as the amounts due to customers for contract work. Amounts received before the related work is performed are included in the consolidated statements of financial position, as a liability, as advance received. Amounts billed for work performed but not yet paid by the customer are included in the consolidated statements of financial position as accounts and other receivables.
Leases	The Company classifies and accounts for leases as either a finance or operating lease, depending on the terms. Leases where the Company assumes substantially all of the risks and rewards of ownership are classified as finance leases. All other leases are classified as operating leases. (i) The Company as lessor Amounts due from lessees under finance leases are recognized as receivables at the amount of the Company’s net investment in the leases. Finance lease income is allocated to accounting periods so as to reflect a constant periodic rate of return on the Company’s net investment outstanding in respect of the leases. Rental income from operating leases is recognized on a straight-line basis over the term of the relevant lease. Initial direct costs incurred in negotiating and arranging an operating lease are added to the carrying amount of the leased asset and recognized on a straight-line basis over the lease term. (ii) The Company as lessee Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards of ownership to the lessee. All other leases are classified as operating leases. Assets held under finance leases are initially recognized as assets of the Company at their fair value at the inception of the lease or, if lower, at the present value of the minimum lease payments. The corresponding liability to the lessor is included in the statement of financial position as a finance lease obligation. Lease payments are apportioned between finance expenses and reduction of the lease obligation so as to achieve a constant rate of interest on the remaining balance of the liability. Finance expenses are recognized immediately in income or loss, unless they are directly attributable to qualifying assets, in which case they are capitalized in accordance with the Company’s general policy on borrowing costs. Contingent rentals are recognized as expenses in the periods in which they are incurred. Operating lease payments are recognized as an expense on a straight-line basis over the lease term, except where another systematic basis is more representative of the time pattern in which economic benefits from the leased asset are consumed. Contingent rentals arising under operating leases are recognized as an expense in the period in which they are incurred. In the event that lease incentives are received to enter into operating leases, such incentives are recognized as a liability. The aggregate benefit of incentives is recognized as a reduction of rental expense on a straight-line basis, except where another systematic basis is more representative of the time pattern in which economic benefits from the leased asset are consumed. (iii) Determining whether an arrangement contains a lease At inception of an arrangement, the Company determines whether the arrangement is or contains a lease. At inception or on reassessment of an arrangement that contains a lease, the Company separates payments and other consideration required by the arrangement into those for the lease and those for other elements on the basis of their relative fair values. If the Company concludes for a finance lease that it is impracticable to separate the payments reliably, then an asset and a liability are recognized at an amount equal to the fair value of the underlying asset.
Foreign currencies	Transactions in foreign currencies are translated to the respective functional currencies of the Company entities at exchange rates at the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are retranslated to the functional currency using the reporting date’s exchange rate. Non-monetary Exchange differences are recognized in profit or loss in the period in which they arise except for: • Exchange differences on foreign currency borrowings relating to assets under construction for future productive use, which are included in the cost of those assets when they are regarded as an adjustment to interest costs on those foreign currency borrowings; • Exchange differences on transactions entered into in order to hedge certain foreign currency risks (refer to note 3.(25) Derivative financial instruments, including hedge accounting); and • Exchange differences on monetary items receivable from or payable to a foreign operation for which settlement is neither planned nor likely to occur (therefore forming part of the net investment in the foreign operation), which are recognized initially in other comprehensive income and reclassified from equity to income or loss on disposal or partial disposal of the net investment. For the purpose of presenting financial statements, the assets and liabilities of the Company’s foreign operations are expressed in Korean won using exchange rates prevailing at the end of the reporting period. Income and expense items are translated at the average exchange rates for the period, unless exchange rates fluctuated significantly during that period, in which case the exchange rates at the dates of the transactions are used. Exchange differences arising, if any, are recognized in other comprehensive income and accumulated in equity. When a foreign operation is disposed of, the relevant amount in the translation is transferred to profit or loss as part of the gain or loss on disposal.
Borrowing costs	The Company capitalizes borrowing costs directly attributable to the acquisition, construction or production of a qualifying asset as part of the cost of that asset. Other borrowing costs are recognized in expense as incurred. A qualifying asset is an asset that requires a substantial period of time to get ready for its intended use or sale. Investment income earned on the temporary investment of specific borrowings pending their expenditure on qualifying assets is deducted from the borrowing costs eligible for capitalization. All other borrowing costs are recognized in income or loss in the period in which they are incurred.
Government grants	Government grants and income related to transfer of assets from customers Government grants are not recognized unless there is reasonable assurance that the Company will comply with the grant’s conditions and that the grant will be received. Benefit from a government loan at a below-market interest rate is treated as a government grant, measured as the difference between proceeds received and the fair value of the loan based on prevailing market interest rates. (i) If the Company received grants related to assets Government grants whose primary condition is that the Company purchase, construct or otherwise acquire long-term assets are deducted in calculating the carrying amount of the asset. The grant is recognized in profit or loss over the life of a depreciable asset as a reduced depreciation expense. (ii) If the Company received grants related to income Government grants which are intended to compensate the Company for expenses incurred are recognized as other income (government grants) in profit or loss over the periods in which the Company recognizes the related costs as expenses. The Company recovers a substantial amount of the cost related to its electric power distribution facilities from customers through the transfer of assets, while the remaining portion is recovered through electricity sales from such customers in the future. As such, the Company believes there exists a continued service obligation to the customers in accordance with IFRIC 18 ‘Transfer of Assets from Customers’ when the Company receives an item of property, equipment, or cash for constructing or acquiring an item of property or equipment, in exchange for supplying electricity to customers. The Company defers the amounts received, which are subsequently recognized as other income on a straight-line basis over the estimated service period which does not exceed the transferred asset’s useful life.
Employee benefits	When an employee has rendered service to the Company during a period, the Company recognizes the contribution payable to a defined contribution plan in exchange for that service as a liability (accrued expense). For defined benefit pension plans and other post-employment benefits, the net periodic pension expense is actuarially determined by “Pension Actuarial System” developed by independent actuaries using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid and that have terms to maturity approximating the terms of the related pension liability. However, if there is not a deep market, market yields on government bonds are used. Net defined benefit liability’s measurement is composed of actuarial gains and losses, return on plan assets excluding net interest on net defined benefit liability, and any change in the effect of the asset ceiling, excluding net interest, which are immediately recognized in other comprehensive income. The actuarial gains or losses recognized in other comprehensive income which will not be reclassified into net profit or loss for later periods are immediately recognized in retained earnings. Past service cost will be recognized as expenses upon the earlier of the date of change or reduction to the plan, or the date of recognizing termination benefits. The retirement benefit obligation recognized in the statement of financial position represents the present value of the defined benefit obligation as adjusted for unrecognized actuarial gains and losses and unrecognized past service cost, and as reduced by the fair value of plan assets. Any asset resulting from this calculation is limited to unrecognized actuarial losses and past service cost, plus the present value of available refunds and reductions in future contributions to the plan.
Income taxes	Income tax expense comprises current and deferred tax. Current tax and deferred tax are recognized in profit or loss except to the extent that it relates to a business combination, or items recognized directly in equity or in other comprehensive income. (i) Current tax Current tax is the expected tax payable or receivable on the taxable profit or loss for the year, using tax rates enacted or substantively enacted at the end of the reporting period and any adjustment to tax payable in respect of previous years. The taxable profit is different from the accounting profit for the period since the taxable profit is calculated excluding the temporary differences, which will be taxable or deductible in determining taxable profit (tax loss) of future periods, and non-taxable non-deductible (ii) Deferred tax Deferred tax is recognized, using the asset-liability method, in respect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for taxation purposes. A deferred tax liability is recognized for all taxable temporary differences. A deferred tax asset is recognized for all deductible temporary differences to the extent that it is probable that taxable profit will be available against which they can be utilized. However, deferred tax is not recognized for the following temporary differences: taxable temporary differences arising on the initial recognition of goodwill, or the initial recognition of assets or liabilities in a transaction that is not a business combination and that affects neither accounting profit or loss nor taxable income. The measurement of deferred tax liabilities and deferred tax assets reflects the tax consequences that would follow from the manner in which the Company expects, at the end of the reporting period, to recover or settle the carrying amount of its assets and liabilities. Deferred tax assets or deferred tax liabilities on investment properties measured at fair value, unless any contrary evidence exists, are measured using the assumption that the carrying amount of the property will be recovered entirely through sale. The Company recognizes a deferred tax liability for all taxable temporary differences associated with investments in subsidiaries, associates, and interests in joint ventures, except to the extent that the Company is able to control the timing of the reversal of the temporary difference and it is probable that the temporary difference will not reverse in the foreseeable future. The Company recognizes a deferred tax asset for all deductible temporary differences arising from investments in subsidiaries and associates, to the extent that it is probable that the temporary difference will reverse in the foreseeable future and taxable profit will be available against which the temporary difference can be utilized. The carrying amount of a deferred tax asset is reviewed at the end of each reporting period and reduces the carrying amount to the extent that it is no longer probable that sufficient taxable profit will be available to allow the benefit of part or all of that deferred tax asset to be utilized. Deferred tax assets and liabilities are measured at the tax rates that are expected to apply to the period when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted by the end of the reporting period. The measurement of deferred tax liabilities and deferred tax assets reflects the tax consequences that would follow from the manner in which the Company expects, at the end of the reporting period to recover or settle the carrying amount of its assets and liabilities. Deferred tax assets and liabilities are offset only if there is a legally enforceable right to offset the related current tax liabilities and assets, and they relate to income taxes levied by the same tax authority and they intend to settle current tax liabilities and assets on a net basis. (iii) Current and deferred tax for the year Current and deferred tax are recognized in income or loss, except when they relate to items that are recognized in other comprehensive income or directly in equity, in which case, the current and deferred tax are also recognized in other comprehensive income or directly in equity respectively. Where current tax or deferred tax arises from the initial accounting for a business combination, the tax effect is included in the accounting for the business combination.
Property, plant and equipment	Property, plant and equipment are initially measured at cost and after initial recognition, are carried at cost less accumulated depreciation and accumulated impairment losses. The cost of property, plant and equipment includes expenditures arising directly from the construction or acquisition of the asset, any costs directly attributable to bringing the asset to the location and condition necessary for it to be capable of operating in the manner intended by management and the initial estimate of the costs of dismantling and removing the item and restoring the site on which it is located. Subsequent costs are recognized in the carrying amount of property, plant and equipment at cost or, if appropriate, as separate items if it is probable that future economic benefits associated with the item will flow to the Company and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day Property, plant and equipment, except for land, are depreciated on a straight-line basis over estimated useful lives that appropriately reflect the pattern in which the asset’s future economic benefits are expected to be consumed. For loaded nuclear fuel related to long-term raw materials and spent nuclear fuels related to asset retirement costs, the Company uses the production method to measure and recognizes as expense the economic benefits of the assets. The estimated useful lives of the Company’s property, plant and equipment are as follows: Useful lives (years) Buildings 8 ~ 40 Structures 8 ~ 50 Machinery 2 ~ 32 Vehicles 3 ~ 8 Loaded heavy water 30 Asset retirement costs 18, 30, 40, 60 Finance lease assets 6 ~ 32 Ships 9 Others 4 ~ 15 A component that is significant compared to the total cost of property, plant and equipment is depreciated over its separate useful life. Depreciation methods, residual values and useful lives of property, plant and equipment are reviewed at the end of each reporting period and if change is deemed appropriate, it is treated as a change in accounting estimate. As a result of such annual review, useful lives of certain machinery were changed during 2016. Depreciation expenses increased by ￦160,985 million for the year ended December 31, 2016. Depreciation expenses increased by ￦160,985 million and ￦130,514 million for the years ended December 31, 2016 and 2017, respectively. Depreciation expenses are expected to increase by ￦91,197 million for the year ending December 31, 2018, and to decrease by ￦382,696 million for the years after December 31, 2018. Property, plant and equipment are derecognized on disposal, or when no future economic benefits are expected from its use or disposal. Gains or losses arising from derecognition of a property, plant and equipment, measured as the difference between the net disposal proceeds and the carrying amount of the asset, are recognized in income or loss when the asset is derecognized.
Investment property	Property held for the purpose of earning rentals or benefiting from capital appreciation is classified as investment property. Investment property is initially measured at its cost. Transaction costs are included in the initial measurement. Subsequently, investment property is carried at depreciated cost less any accumulated impairment losses. Subsequent costs are recognized in the carrying amount of investment property at cost or, if appropriate, as separate items if it is probable that future economic benefits associated with the item will flow to the Company and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. The costs of the day-to-day Investment property except for land, are depreciated on a straight-line basis over 8 ~ 40 years as estimated useful lives. The estimated useful lives, residual values and depreciation method are reviewed at the end of each reporting period, with the effect of any changes in estimate accounted for on a prospective basis. An investment property is derecognized upon disposal or when the investment property is permanently withdrawn from use and no future economic benefits are expected from the disposal. Any gain or loss arising on derecognition of the property (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) is included in income or loss in the period in which the property is derecognized.
Intangible assets	Intangible assets (i) Intangible assets acquired separately Intangible assets with finite useful lives that are acquired separately are carried at cost less accumulated amortization and accumulated impairment losses. Amortization is recognized on a straight-line basis over their estimated useful lives. The estimated useful life and amortization method are reviewed at the end of each reporting period, with the effect of any changes in estimate being accounted for on a prospective basis. Intangible assets with indefinite useful lives that are acquired separately are carried at cost less accumulated impairment losses. (ii) Research and development Expenditure on research activities is recognized as an expense in the period in which it is incurred. An internally-generated intangible asset arising from development (or from the development phase of an internal project) is recognized if, and only if, all of the following have been demonstrated: • The technical feasibility of completing the intangible asset so that it will be available for use or sale; • The intention to complete the intangible asset and use or sell it; • The ability to use or sell the intangible asset; • How the intangible asset will generate probable future economic benefits; • The availability of adequate technical, financial and other resources to complete the development and to use or sell the intangible asset; and • The ability to measure reliably the expenditure attributable to the intangible asset during its development. The amount initially recognized for internally-generated intangible assets is the sum of the expenditure incurred from the date when the intangible asset first meets the recognition criteria listed above. When the development expenditure does not meet the criteria listed above, an internally-generated intangible asset cannot be recognized and the expenditure is recognized in income or loss in the period in which it is incurred. Internally-generated intangible assets are reported at cost less accumulated amortization and accumulated impairment losses. The estimated useful lives and amortization methods of the Company’s intangible assets with finite useful lives are as follows: Useful lives (years) Amortization methods Usage rights for donated assets 10 ~ 20 Straight line Software 4, 5 Straight line Industrial rights 5, 10 Straight line Development expenses 5 Straight line Leasehold rights 10 Straight line Mining right — Unit of production Others 3 ~ 50 or Indefinite Straight line (iii) Intangible assets acquired in a business combination Intangible assets that are acquired in a business combination are recognized separately from goodwill are initially recognized at their fair value at the acquisition date (which is regarded as their cost). Subsequent to initial recognition, intangible assets acquired in a business combination are reported at cost less accumulated amortization and accumulated impairment losses, on the same basis as intangible assets that are acquired separately. (iv) Derecognition of intangible assets An intangible asset is derecognized on disposal, or when no future economic benefits are expected from its use or disposal. Gains or losses arising from derecognition of an intangible asset are measured as the difference between the net disposal proceeds and the carrying amount of the asset, and are recognized in income or loss when the asset is derecognized.
Greenhouse gas emissions rights (allowances) and obligations	Greenhouse gas emissions rights (allowances) and obligations In connection with Enforcement of Allocation and Trading of Greenhouse Gas Emissions Allowances, the Company applies the following accounting policies for greenhouse gas emissions rights and obligations. (i) Greenhouse gas emissions rights Greenhouse gas emissions rights consist of the allowances received free of charge from the government and the ones purchased. The cost of the greenhouse gas emissions rights includes expenditures arising directly from the acquisition and any other costs incurred during normal course of the acquisition. Greenhouse gas emissions rights are held by the Company to fulfill the legal obligation and recorded as intangible assets. To the extent that the portion to be submitted to the government within one year from the end of reporting period, the greenhouse gas emissions rights are classified as current assets. Greenhouse gas emissions rights recorded as intangible assets are initially measured at cost and substantially remeasured at cost less accumulated impairment losses. Greenhouse gas emissions rights are derecognized on submission to the government or when no future economic benefits are expected from its use or disposal. (ii) Greenhouse gas emissions obligations Greenhouse gas emissions obligations are the Company’s present legal obligation to submit the greenhouse gas emissions allowances to the government and recognized when an outflow of resources is probable and a reliable estimate can be made of the amount of the obligation. Greenhouse gas emissions obligations are measured as the sum of the carrying amount of the allocated rights that will be submitted to the government and the best estimate of expenditure required to settle the obligation at the end of the reporting period for any excess emission.
Impairment of non-financial assets other than goodwill	non-financial At the end of each reporting period, the Company reviews the carrying amounts of its tangible and intangible assets with definite useful lives to determine whether there is any indication that those assets have suffered an impairment loss. If any such indication exists, the recoverable amount of the asset is estimated in order to determine the extent of the impairment loss (if any). Where it is not possible to estimate the recoverable amount of an individual asset, the Company estimates the recoverable amount of the cash-generating unit to which the asset belongs. Where a reasonable and consistent basis of allocation can be identified, corporate assets are also allocated to individual cash-generating units, or otherwise they are allocated to the smallest group of cash-generating units for which a reasonable and consistent allocation basis can be identified. Intangible assets with indefinite useful lives and intangible assets not yet available for use are tested for impairment at least annually, and whenever there is an indication that the asset may be impaired. Recoverable amount is the higher of fair value less costs to sell and value in use. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax If the recoverable amount of an asset (or a cash-generating unit) is estimated to be less than its carrying amount, the carrying amount of the asset (or the cash-generating unit) is reduced to its recoverable amount. An impairment loss is recognized immediately in profit or loss, unless the relevant asset is carried at a revalued amount, in which case the impairment loss is treated as a revaluation decrease. When an impairment loss subsequently reverses, the carrying amount of the asset (or a cash-generating unit) is increased to the revised estimate of its recoverable amount, to the extent the increased carrying amount does not exceed the carrying amount that would have been determined had no impairment loss been recognized for the asset (or cash-generating unit) in prior years. A reversal of an impairment loss is recognized immediately in profit or loss, unless the relevant asset is carried at a revalued amount, in which case the reversal of the impairment loss is treated as a revaluation increase.
Inventories	Inventories are measured at the lower of cost and net realizable value. Cost of inventories for inventories in transit are measured by using specific identification method. Cost of inventories, except for those in transit, are measured under the weighted average method and consists of the purchase price, cost of conversion and other costs incurred in bringing the inventories to their present location and condition. Net realizable value is the estimated selling price in the ordinary course of business, less the estimated costs of completion and selling expenses. The amount of any write-down of inventories to net realizable value and all losses of inventories are recognized as an expense in the period the write-down or loss occurs. The amount of any reversal of any write-down of inventories, arising from an increase in net realizable value, are recognized as a reduction in the amount of inventories recognized as an expense in the period in which the reversal occurs.
Provisions	Provisions are recognized when the Company has a present legal or constructive obligation as a result of a past event, it is probable that an outflow of resources embodying economic benefits will be required to settle the obligation and a reliable estimate can be made of the amount of the obligation. The risks and uncertainties that inevitably surround many events and circumstances are taken into account in reaching the best estimate of a provision. Where the effect of the time value of money is material, provisions are determined at the present value of the expected future cash flows. Where some or all of the expenditures required to settle a provision are expected to be reimbursed by another party, the reimbursement shall be recognized when, and only when, it is virtually certain that reimbursement will be received if the entity settles the obligation. The reimbursement shall be treated as a separate asset. Provisions are reviewed at the end of each reporting period and adjusted to reflect the current best estimates. If it is no longer probable that an outflow of resources embodying economic benefits will be required to settle the obligation, the provision is reversed. (i) Provision for employment benefits The Company determines the provision for employment benefits as the incentive payments based on the results of the individual performance evaluation or management assessment. (ii) Provision for decommissioning costs of nuclear power plants The Company records the fair value of estimated decommissioning costs as a liability in the period in which the Company incurs a legal obligation associated with retirement of long-lived assets that result from acquisition, construction, development and/or normal use of the assets. Accretion expense consists of period-to-period (iii) Provision for disposal of spent nuclear fuel Under the Radioactive Waste Management Act, the Company is levied to pay the spent nuclear fuel fund for the management of spent nuclear fuel. The Company recognizes the provision of present value of the payments. (iv) Provision for low and intermediate radioactive wastes Under the Radioactive Waste Management Act, the Company recognizes the provision for the disposal of low and intermediate radioactive wastes in best estimate of the expenditure required to settle the present obligation. (v) Provision for Polychlorinated Biphenyls (“PCBs”) Under the regulation of Persistent Organic Pollutants Management Act, enacted in 2007, the Company is required to remove PCBs, a toxin, from the insulating oil of its transformers by 2025. As a result of the enactments, the Company is required to inspect the PCBs contents of transformers and dispose of PCBs in excess of safety standards under the legally settled procedures. The Company’s estimates and assumptions used to determine fair value can be affected by many factors, such as the estimated costs of inspection and disposal, inflation rate, discount rate, regulations and the general economy. (vi) Provisions for power plant regional support program Power plant regional support programs consist of scholarship programs to local students, local economy support programs, local culture support programs, environment development programs, and local welfare programs. The Company recognizes the provision in relation to power plant regional support program. (vii) Provisions for transmission and transformation facilities-neighboring areas support program The Company has present obligation to conduct transmission and transformation facilities-neighboring areas support program under Act on assistance to transmission and transformation facilities-neighboring areas. The Company recognizes the provision of estimated amount to fulfill the obligation. (viii) Renewable Portfolio Standard (“RPS”) provisions RPS program is required to generate a specified percentage of total electricity to be generated in the form of renewable energy and provisions are recognized for the governmental regulations to require the production of energies from renewable energy sources such as solar, wind and biomass.
Non-derivative financial assets	The Company recognizes and measures non-derivative held-to-maturity available-for-sale non-derivative A regular way purchase or sale of financial assets shall be recognized and derecognized, as applicable, using trade date accounting or settlement date accounting. A regular way purchase or sale is a purchase or sale of a financial asset under a contract whose terms require delivery of the asset within the time frame established generally by regulation or convention in the marketplace concerned. (i) Effective interest method The effective interest method is a method of calculating the amortized cost of a debt instrument and of allocating interest income over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash receipts (including all fees and points paid or received that form an integral part of the effective interest rate, transaction costs and other premiums or discounts) through the expected life of the debt instrument, or, where appropriate, a shorter period, to the net carrying amount on initial recognition. Income is recognized on an effective interest basis for debt instruments other than those financial assets classified as financial assets at fair value through profit or loss. (ii) Financial assets at fair value through profit or loss (FVTPL) A financial asset is classified as financial assets are classified at fair value through profit or loss if it is held for trading or is designated as such upon initial recognition. Upon initial recognition, transaction costs are recognized in profit or loss when incurred. A financial assets its acquired principally for the purpose of selling it in the near term are classified as a short-term financial assets held for trading and also all the derivatives including an embedded derivate that is not designated and effective as a hedging instrument are classified at the short-term trading financial asset as well. Financial assets at fair value through profit or loss are measured at fair value, and changes therein are recognized in profit or loss. A financial asset is classified as held for trading if: • It has been acquired principally for the purpose of selling it in the near term; or • On initial recognition it is part of a portfolio of identified financial instruments that the Company manages together and has a recent actual pattern of short term profit taking; or • It is derivative, including an embedded derivative that is not designated and effective as a hedging instrument. A financial asset other than a financial asset held for trading may be designated as at financial assets at fair value through profit or loss upon initial recognition if: • Such designation eliminates or significantly reduces a measurement or recognition inconsistency that would otherwise arise; or • The financial asset forms part of a group of financial assets or financial liabilities or both, which is managed and its’ performance is evaluated on a fair value basis in accordance with the Company’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or • It forms a part of a contract containing one or more embedded derivatives, and with IAS No. 39, Financial Instruments; Recognition and Measurement permits the entire combined contract (asset or liability) to be designated as at financial assets at fair value through profit or loss. Financial assets at fair value through profit or loss are stated at fair value, with any gains or losses arising on re-measurement (iii) Held-to-maturity A non-derivative held-to-maturity held-to-maturity (iv) Available-for-sale Available-for-sale non-derivative available-for-sale held-to-maturity Gains and losses arising from changes in fair value are recognized in other comprehensive income and accumulated in the valuation reserve. However, impairment losses, interest calculated using the effective interest method, and foreign exchange gains and losses on monetary assets are recognized in income or loss. Unquoted equity investments which are not traded in an active market, whose fair value cannot be measured reliably are carried at cost. When a financial asset is derecognized or impairment losses are recognized, the cumulative gain or loss previously recognized in other comprehensive income is reclassified from equity to profit or loss. Dividends on an available-for-sale The fair value of available-for-sale (v) Loans and receivables Loans and receivables are financial assets with fixed or determinable payments that are not quoted in an active market. Subsequent to initial recognition, loans and receivables are measured at amortized cost using the effective interest method except for loans and receivables of which the effect of discounting is immaterial. (vi) Impairment of financial assets Financial assets, other than those at financial assets at fair value through profit or loss, are assessed for indicators of impairment at the end of each reporting period. Financial assets are considered to be impaired when there is objective evidence that, as a result of one or more events that occurred after the initial recognition of the financial asset, the estimated future cash flows of the investment have been affected. For listed and unlisted equity investments classified as available-for-sale For all other financial assets, objective evidence of impairment could include: • Significant financial difficulty of the issuer or counterparty; or • Breach of contract, such as a default or delinquency in interest or principal payments, or • It becoming probable that the borrower will enter bankruptcy or financial re-organization; • The disappearance of an active market for that financial asset because of financial difficulties. For certain categories of financial asset, such as trade receivables, assets that are assessed not to be impaired individually are, in addition, assessed for impairment on a collective basis. Objective evidence of impairment for a portfolio of receivables could include the Company’s past experience of collecting payments, an increase in the number of delayed payments in the portfolio past the average credit period and, as well as observable changes in national or local economic conditions that correlate with default on receivables. For financial assets recorded at amortized cost, the amount of the impairment loss recognized is the difference between the asset’s carrying amount and the present value of estimated future cash flows, discounted at the financial asset’s original effective interest rate. For financial assets carried at cost, the amount of the impairment loss is measured as the difference between the asset’s carrying amount and the present value of the estimated future cash flows discounted at the current market rate of return for a similar financial asset. Such impairment loss will not be reversed in subsequent periods. The carrying amount of the financial asset is reduced by the impairment loss directly for all financial assets with the exception of trade receivables, where the carrying amount is reduced through the use of an allowance account. When a trade receivable is considered uncollectible, it is written off against the allowance account. Subsequent recoveries of amounts previously written off are credited against the allowance account. Changes in the carrying amount of the allowance account are recognized in income or loss. When an available-for-sale For financial assets measured at amortized cost, if, in a subsequent period, the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized, the previously recognized impairment loss is reversed through profit or loss to the extent that the carrying amount of the investment at the date the impairment is reversed does not exceed what the amortized cost would have been had the impairment not been recognized. In respect of available-for-sale available-for-sale (vii) De-recognition The Company derecognizes a financial asset when the contractual rights to the cash flows from the asset expire, or it transfers the rights to receive the contractual cash flows on the financial asset in a transaction in which substantially all the risks and rewards of ownership of the financial asset are transferred. Any interest in transferred financial assets that is created or retained by the Company is recognized as a separate asset or liability. If the Company retains substantially all the risks and rewards of ownership of the transferred financial assets, the Company continues to recognize the transferred financial assets and recognizes financial liabilities for the consideration received. On de-recognition On de-recognition
Non-derivative financial liabilities and equity instruments issued by the Company	(i) Classification as debt or equity Debt and equity instruments are classified as either financial liabilities or as equity in accordance with the substance of the contractual arrangement. (ii) Equity instruments An equity instrument is any contract that evidences a residual interest in the assets of an entity after deducting all of its liabilities. Equity instruments issued by the Company are recognized at the proceeds received, net of direct issue costs. Repurchase of the Company’s own equity instruments is recognized and deducted directly in equity. No gain or loss is recognized in income or loss on the purchase, sale, issue or cancelation of the Company’s own equity instruments. (iii) Financial liabilities Financial liabilities are recognized when the Company becomes a party to the contractual provisions of the instruments. Financial liabilities are initially measured at fair value. Transaction cost that are directly attributable to the issue of financial liabilities are added to or deducted from the fair value of the financial liabilities, as appropriate, on initial recognition. Transaction cost directly attributable to acquisition of financial liabilities at fair value through profit or loss are recognized immediately in profit or loss. Financial liabilities are classified as either financial liabilities at fair value through profit or loss or other financial liabilities. (iv) Financial liabilities at fair value through profit or loss (FVTPL) Financial liabilities are classified as at financial liabilities at fair value through profit or loss when the financial liability is either held for trading or it is designated as financial liabilities at fair value through profit or loss. A financial liability is classified as held for trading if: • It has been acquired principally for the purpose of repurchasing it in the near term; or • On initial recognition it is part of a portfolio of identified financial instruments that the Company manages together and has a recent actual pattern of short-term profit-taking; or • It is a derivative that is not designated and effective as a hedging instrument. A financial liability other than a financial liability held for trading may be designated as at FVTPL upon initial recognition if: • Such designation eliminates or significantly reduces a measurement or recognition inconsistency that would otherwise arise; or • The financial liability forms part of a Company of financial assets or financial liabilities or both, which is managed and its performance is evaluated on a fair value basis, in accordance with the Company’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or • It forms part of a contract containing one or more embedded derivatives, and IAS 39 ‘Financial Instruments: Recognition and Measurement’, permits the entire combined contract (asset or liability) to be designated as at FVTPL. Financial liabilities at fair value through profit or loss are stated at fair value, with any gains or losses arising on re-measurement (v) Other financial liabilities Other financial liabilities, including borrowings, are initially measured at fair value, net of transaction costs. Other financial liabilities are subsequently measured at amortized cost using the effective interest method, with interest expense recognized on an effective yield basis. The effective interest method is a method of calculating the amortized cost of a financial liability and of allocating interest expense over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash payments through the expected life of the financial liability, or (where appropriate) a shorter period, to the net carrying amount on initial recognition. (vi) Financial guarantee contract liabilities Financial guarantee contract liabilities are initially measured at their fair values and, if not designated as at FVTPL, are subsequently measured at the higher of: (a) the amount of the obligation under the contract, as determined in accordance with IAS 37 ‘Provisions, Contingent Liabilities and Contingent Assets; or (b) the amount initially recognized less, cumulative amortization recognized in accordance with IAS 18 ‘Revenue’. (vii) De-recognition The Company derecognizes financial liabilities when, and only when, the Company’s obligations are discharged, canceled or they expire. The difference between the carrying amount of the financial liability derecognized and the consideration paid and payable is recognized in income or loss.
Service Concession Arrangements	Service Concession Arrangements The Company recognizes revenues from construction services and operating services related to service concession arrangements in accordance with IAS 11 ’Construction Contracts’ and IAS 18 ‘Revenue’, respectively. If the Company performs more than one service under a single contract or arrangement, consideration received or receivable is allocated by reference to the relative fair values of the services delivered, when the amounts are separately identifiable. The Company recognizes a financial asset to the extent that it has an unconditional contractual right to receive cash or another financial asset for the construction services and an intangible asset to the extent that it receives a right (license) to charge users of the public service. Borrowing costs attributable to the arrangement are recognized as an expense in the period in which they are incurred unless the Company has a contractual right to receive an intangible asset (a right to charge users of the public service). In this case, borrowing costs attributable to the arrangement are capitalized during the construction phase of the arrangement.
Derivative financial instruments, including hedge accounting	The Company enters into a variety of derivative financial instruments to manage its exposure to interest rate and foreign exchange rate risk, including foreign exchange forward contracts, interest rate swaps and cross currency swaps and others. Derivatives are initially recognized at fair value. Subsequent to initial recognition, derivatives are measured at fair value. The resulting gain or loss is recognized in income or loss immediately unless the derivative is designated and effective as a hedging instrument, in such case the timing of the recognition in income or loss depends on the nature of the hedge relationship. A derivative with a positive fair value is recognized as a financial asset; a derivative with a negative fair value is recognized as a financial liability. A derivative is presented as a non-current non-current (i) Separable embedded derivatives Derivatives embedded in other financial instruments or other host contracts are treated as separate derivatives when their risks and characteristics are not closely related to those of the host contracts and when the host contracts are not measured at FVTPL. An embedded derivative is presented as a non-current non-current (ii) Hedge accounting The Company designates certain hedging instruments, which include derivatives, embedded derivatives and non-derivatives At the inception of the hedge relationship, the entity documents the relationship between the hedging instrument and the hedged item, along with its risk management objectives and its strategy for undertaking various hedge transactions. Furthermore, at the inception of the hedge and on an ongoing basis, the Company documents whether the hedging instrument is highly effective in offsetting changes in fair values or cash flows of the hedged item. (iii) Fair value hedges Changes in the fair value of derivatives that are designated and qualify as fair value hedges are recognized in income or loss immediately, together with any changes in the fair value of the hedged asset or liability that are attributable to the hedged risk. The changes in the fair value of the hedging instrument and the change in the hedged item attributable to the hedged risk relating to the hedged items are recognized in the consolidated statements of comprehensive income. Hedge accounting is discontinued when the Company revokes the hedging relationship, when the hedging instrument expires or is sold, terminated, or exercised, or when it no longer qualifies for hedge accounting. The fair value adjustment to the carrying amount of the hedged item arising from the hedged risk is amortized as income or loss as of that date. (iv) Cash flow hedges The effective portion of changes in the fair value of derivatives that are designated and qualify as cash flow hedges is recognized in other comprehensive income. The gain or loss relating to the ineffective portion is recognized immediately in income or loss, and is included in the ‘finance income and expense’. Amounts previously recognized in other comprehensive income and accumulated in equity are reclassified to income or loss in the periods when the hedged item is recognized in income or loss, in the same line of the consolidated statement of comprehensive income as the recognized hedged item. However, when the forecast transaction that is hedged results in the recognition of a non-financial non-financial non-financial non-financial Hedge accounting is discontinued when the Company revokes the hedging relationship, when the hedging instrument expires or is sold, terminated, or exercised, or it no longer qualifies for hedge accounting. Any gain or loss accumulated in equity at that time remains in equity and is recognized when the forecast transaction is ultimately recognized in income or loss. When a forecast transaction is no longer expected to occur, the gain or loss accumulated in equity is recognized immediately in income or loss.

Reporting Entity (Description59

Reporting Entity (Description of the controlling company) (Tables)	12 Months Ended
	Dec. 31, 2017
Reporting Entity (Description of the controlling company) [Abstract]
The Company's shareholders	As of December 31, 2017, KEPCO’s share capital amounts to ￦3,209,820 million and KEPCO’s shareholders are as follows: Number of shares Percentage of ownership Government of the Republic of Korea 116,841,794 18.20 % Korea Development Bank 211,235,264 32.90 % Foreign investors 194,050,746 30.23 % Other 119,836,273 18.67 % 641,964,077 100.00 %

Basis of Preparation (Tables)

Basis of Preparation (Tables)	12 Months Ended
	Dec. 31, 2017
Basis of Preparation [Abstract]
Impacts on financial assets from initial application of IFRS9	Based on the result of the detailed assessment to date, the expected impacts on the Company’s financial assets (excluding derivative instruments) on the date of initial application (January 1, 2018) are as follows: Classification based on IAS 39 Classification based on IFRS 9 Amount based Amount based In millions of won Financial assets at FVTPL FVTPL ￦ 111,512 111,512 Loans and receivables Amortized cost 15,203,663 14,412,339 Loans and receivables FVTPL — 791,324 Available-for-sale FVOCI 699,833 476,941 Available-for-sale FVTPL — 222,892 Held-to-maturity Amortized cost 3,144 3,144 Total financial assets (excluding derivative instruments) ￦ 16,018,152 16,018,152
Measurement of loss allowances under IFRS9	Under IFRS 9, impairment losses are likely to be recognized earlier than using the incurred loss model under the existing guidance in IAS 39 as loss allowances will be measured on either of the 12-month Classification Loss allowances Stage 1 Credit risk has not increased significantly since the initial recognition 12-month ECL: ECLs that resulted from possible default events within the 12 months after the reporting date Stage 2 Credit risk has increased significantly since the initial recognition Lifetime ECL: ECL that resulted from all possible default events over the expected life of a financial instrument Stage 3 Credit-impaire
Impacts on loss allowances of financial assets from initial application of IFRS9	Under adoption of IFRS 9, the Company plans to elect to measure the loss allowance at an amount equal to lifetime expected credit losses for trade receivables, contract assets and lease receivables that include a significant financing component. Based on the result of the detailed assessment to date, the expected impacts on the Company’s loss allowances on the date of initial application (January 1, 2018) are as follows: Type Amount based on IAS 39 (A) Amount based on IFRS 9 (B) Increase (decrease) (B-A) In millions of won Trade and other receivables ￦ 251,591 258,360 6,769 Other financial assets 8,948 8,948 — Total ￦ 260,539 267,308 6,769

Significant Accounting Polici61

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Property, plant and equipment, estimated useful lives	The estimated useful lives of the Company’s property, plant and equipment are as follows: Useful lives (years) Buildings 8 ~ 40 Structures 8 ~ 50 Machinery 2 ~ 32 Vehicles 3 ~ 8 Loaded heavy water 30 Asset retirement costs 18, 30, 40, 60 Finance lease assets 6 ~ 32 Ships 9 Others 4 ~ 15
Intangible assets, estimated useful lives	The estimated useful lives and amortization methods of the Company’s intangible assets with finite useful lives are as follows: Useful lives (years) Amortization methods Usage rights for donated assets 10 ~ 20 Straight line Software 4, 5 Straight line Industrial rights 5, 10 Straight line Development expenses 5 Straight line Leasehold rights 10 Straight line Mining right — Unit of production Others 3 ~ 50 or Indefinite Straight line

Segment, Geographic and Other62

Segment, Geographic and Other Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment, Geographic and Other Information [Abstract]
Segment determination and explanation of the measurements	The Company’s operating segments are its business components that generate discrete financial information that is reported to and regularly reviewed by the Company’s the chief operating decision maker, the Chief Executive Officer, for the purpose of resource allocation and assessment of segment performance. The Company’s reportable segments are ‘Transmission and distribution’, ‘Electric power generation (Nuclear)’, ‘Electric power generation (Non-nuclear)’, Segment operating profit (loss) is determined the same way that consolidated operating profit is determined under IFRS without any adjustment for corporate allocations. The accounting policies used by each segment are consistent with the accounting policies used in the preparation of the consolidated financial statements. Segment assets and liabilities are determined based on separate financial statements of the entities instead of on a consolidated basis. There are various transactions between the reportable segments, including sales of property, plant and equipment and so on, that are conducted on an arms-length basis at market prices that would be applicable to an independent third-party. For subsidiaries which are in a different segment from that of its immediate parent company, their carrying amount in separate financial statements is eliminated in the consolidating adjustments in the tables below. In addition, consolidation adjustments in the table below include adjustments of the amount of investment in associates and joint ventures from the cost basis amount reflected in segment assets to that determined using equity method in the consolidated financial statements.
Financial information of the segments	Financial information of the segments for the years ended December 31, 2015, 2016 and 2017, respectively, are as follows: 2015 Segment Total Intersegment Revenue Depreciation Interest Interest Profit (loss) Employee Loss on Increase in Operating In millions of won Transmission and distribution ￦ 58,164,394 1,230,975 56,933,419 2,859,037 132,809 1,092,594 220,406 135,261 359,521 872,096 13,319,310 Electric power generation (Nuclear) 10,642,352 10,596,189 46,163 3,070,828 24,612 532,490 (595 ) 54,572 — 401,839 3,806,617 Electric power generation (Non-nuclear) 21,469,345 20,906,081 563,264 2,337,353 22,171 319,647 (10,686 ) 74,007 5,305 148,053 2,704,260 Plant maintenance & engineering service 2,533,887 2,016,699 517,188 85,662 12,293 542 (1,746 ) 74,542 — 174,912 332,531 Others 672,250 150,557 521,693 27,491 108,104 127,684 — 343 230 34 80,165 Consolidation adjustments (34,900,501 ) (34,900,501 ) — (38,987 ) (58,404 ) (57,273 ) — (24,033 ) — 5,790 37,993 ￦ 58,581,727 — 58,581,727 8,341,384 241,585 2,015,684 207,379 314,692 365,056 1,602,724 20,280,876 Finance income 1,182,988 Finance expense (3,015,457 ) Profit related to associates and joint ventures 207,379 Profit before income tax ￦ 18,655,786 2016 Segment Total Intersegment Revenue Depreciation Interest Interest Profit (loss) Employee Loss on Increase in Operating In millions of won Transmission and distribution ￦ 59,862,284 1,890,489 57,971,795 3,226,700 80,882 844,200 (128,402 ) 162,326 424,356 711,430 5,274,308 Electric power generation (Nuclear) 11,168,579 11,129,385 39,194 3,130,820 33,111 474,590 (1,082 ) 70,582 — 576,223 3,770,165 Electric power generation (Non-nuclear) 21,394,223 20,561,044 833,179 2,523,306 24,171 359,607 (8,342 ) 79,846 2,133 276,619 3,211,684 Plant maintenance & engineering service 2,618,388 2,190,207 428,181 98,843 10,672 2,156 478 86,268 — 221,301 210,680 Others 567,836 77,098 490,738 26,817 115,928 97,926 — 1,050 30 168 76,336 Consolidation adjustments (35,848,223 ) (35,848,223 ) — (45,498 ) (22,986 ) (25,611 ) — (26,319 ) — (3,009 ) (246,813 ) ￦ 59,763,087 — 59,763,087 8,960,988 241,778 1,752,868 (137,348 ) 373,753 426,519 1,782,732 12,296,360 Finance income 791,543 Finance expense (2,437,087 ) Loss related to associates and joint ventures (137,348 ) Profit before income tax ￦ 10,513,468 2017 Segment Total Intersegment Revenue Depreciation Interest Interest Profit (loss) Employee Loss on Increase in Operating In millions of won Transmission and distribution ￦ 59,486,766 2,044,160 57,442,606 3,466,410 49,987 737,971 (105,166 ) 158,738 384,595 885,195 1,902,634 Electric power generation (Nuclear) 9,415,752 9,359,468 56,284 3,267,510 21,034 487,503 3,637 80,809 — 801,800 1,347,794 Electric power generation (Non-nuclear) 22,795,816 21,885,251 910,565 2,954,375 18,860 486,176 (6,718 ) 94,075 39,335 171,457 1,523,497 Plant maintenance & engineering service 2,621,440 2,211,716 409,724 109,001 10,801 2,967 (70 ) 87,344 161 219,382 265,593 Others 655,062 138,352 516,710 36,001 130,003 103,782 — 861 — (967 ) 113,296 Consolidation adjustments (35,638,947 ) (35,638,947 ) — (59,586 ) (24,542 ) (28,847 ) — (30,467 ) — (386,747 ) 167,055 ￦ 59,335,889 — 59,335,889 9,773,711 206,143 1,789,552 (108,317 ) 391,360 424,091 1,690,120 5,319,869 Finance income 1,530,618 Finance expense (3,127,952 ) Loss related to associates and joint ventures (108,317 ) Profit before income tax ￦ 3,614,218
Information related to segment assets and liabilities	2016 Segment Segment assets Investments Acquisition of non-current Segment In millions of won Transmission and distribution ￦ 105,321,129 4,121,462 6,345,004 49,854,420 Electric power generation (Nuclear) 52,782,915 15,384 1,945,610 27,366,938 Electric power generation (Non-nuclear) 47,427,642 1,320,203 3,508,313 26,205,049 Plant maintenance & engineering service 3,106,909 53,399 180,715 1,218,047 Others 7,423,132 — 365,470 2,761,262 Segment totals 216,061,727 5,510,448 12,345,112 107,405,716 Consolidation adjustments: Elimination of inter-segment amounts (39,114,371 ) — (191,901 ) (5,811,800 ) Equity method adjustment 906,239 — — — Deferred taxes (5,830 ) — — 4,301,404 Others (10,723 ) — — (1,108,823 ) (38,224,685 ) — (191,901 ) (2,619,219 ) Consolidated totals ￦ 177,837,042 5,510,448 12,153,211 104,786,497 2017 Segment Segment assets Investments Acquisition of non-current Segment In millions of won Transmission and distribution ￦ 106,540,154 3,366,309 6,606,512 50,757,798 Electric power generation (Nuclear) 55,011,096 11,843 2,083,967 29,252,816 Electric power generation (Non-nuclear) 47,938,084 1,904,224 3,250,524 26,337,295 Plant maintenance & engineering service 3,273,959 48,320 145,779 1,176,627 Others 7,798,400 — 569,447 3,013,743 Segment totals 220,561,693 5,330,696 12,656,229 110,538,279 Consolidation adjustments: Elimination of inter-segment amounts (39,517,829 ) — 23,616 (5,239,156 ) Equity method adjustment 754,314 — — — Deferred taxes 2,215 — — 5,339,450 Others (11,478 ) — — (1,814,299 ) (38,772,778 ) — 23,616 (1,714,005 ) Consolidated totals ￦ 181,788,915 5,330,696 12,679,845 108,824,274
Geographic information	Electric sales, the main operations of the Company, are conducted in the Republic of Korea where the controlling company is located. The following information on revenue from external customers and non-current Geographical unit Revenue from external customers Non-current 2015 2016 2017 2015 2016 2017 In millions of won Domestic ￦ 54,351,076 55,310,011 55,652,807 143,788,043 148,297,677 153,436,810 Overseas(*1) 4,230,651 4,453,076 3,683,082 4,526,395 4,474,699 4,497,535 ￦ 58,581,727 59,763,087 59,335,889 148,314,438 152,772,376 157,934,345 (*1) Middle East and other Asian countries make up the majority of overseas revenue and non-current (*2) Amount excludes financial assets and deferred tax assets.
Information on significant customers	There is no individual customer comprising more than 10% of the Company’s revenue for the years ended December 31, 2015, 2016 and 2017.

Classification of Financial I63

Classification of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Classification of Financial Instruments [Abstract]
Classification of financial assets	2016 Financial Loans and Available-for-sale Held-to-maturity Derivative assets Total In millions of won Current assets Cash and cash equivalents ￦ — 3,051,353 — — — 3,051,353 Current financial assets Held-to-maturity — — — 114 — 114 Derivative assets 79,709 — — — 113,574 193,283 Other financial assets — 2,478,592 — — — 2,478,592 Trade and other receivables — 7,788,876 — — — 7,788,876 79,709 13,318,821 — 114 113,574 13,512,218 Non-current Non-current Available-for-sale — — 1,014,732 — — 1,014,732 Held-to-maturity — — — 3,130 — 3,130 Derivative assets 287,768 — — — 300,323 588,091 Other financial assets — 1,051,541 — — — 1,051,541 Trade and other receivables — 1,903,515 — — — 1,903,515 287,768 2,955,056 1,014,732 3,130 300,323 4,561,009 ￦ 367,477 16,273,877 1,014,732 3,244 413,897 18,073,227 2017 Financial Loans and Available-for-sale Held-to-maturity Derivative assets Total In millions of won Current assets Cash and cash equivalents ￦ — 2,369,739 — — — 2,369,739 Current financial assets Held-to-maturity — — — 5 — 5 Derivative assets 12,923 — — — 12 12,935 Other financial assets — 1,945,417 — — — 1,945,417 Trade and other receivables — 7,928,972 — — — 7,928,972 12,923 12,244,128 — 5 12 12,257,068 Non-current Non-current Available-for-sale — — 699,833 — — 699,833 Held-to-maturity — — — 3,139 — 3,139 Derivative assets 9,097 — — — 10,594 19,691 Other financial assets 111,512 1,204,738 — — — 1,316,250 Trade and other receivables — 1,754,797 — — — 1,754,797 120,609 2,959,535 699,833 3,139 10,594 3,793,710 ￦ 133,532 15,203,663 699,833 3,144 10,606 16,050,778
Classification of financial liabilities	2016 Financial liabilities at fair value through profit or loss Financial liabilities Derivative liabilities Total In millions of won Current liabilities Borrowings ￦ — 1,115,521 — 1,115,521 Debt securities — 7,823,557 — 7,823,557 Derivative liabilities 3,251 — — 3,251 Trade and other payables — 5,585,411 — 5,585,411 3,251 14,524,489 14,527,740 Non-current Borrowings — 1,773,891 — 1,773,891 Debt securities — 42,926,236 — 42,926,236 Derivative liabilities 18,278 — 117,157 135,435 Trade and other payables — 3,558,175 — 3,558,175 18,278 48,258,302 117,157 48,393,737 ￦ 21,529 62,782,791 117,157 62,921,477 2017 Financial liabilities at fair value through profit or loss Financial liabilities Derivative liabilities Total In millions of won Current liabilities Borrowings ￦ — 1,165,985 — 1,165,985 Debt securities — 7,957,300 — 7,957,300 Derivative liabilities 51,090 — 20,177 71,267 Trade and other payables — 5,999,521 — 5,999,521 51,090 15,122,806 20,177 15,194,073 Non-current Borrowings — 2,434,624 — 2,434,624 Debt securities — 43,189,483 — 43,189,483 Derivative liabilities 99,839 — 256,953 356,792 Trade and other payables — 3,223,480 — 3,223,480 99,839 48,847,587 256,953 49,204,379 ￦ 150,929 63,970,393 277,130 64,398,452
Classification of comprehensive income (loss) from financial instruments	2015 2016 2017 In millions of won Cash and cash equivalents Interest income ￦ 54,687 61,380 35,474 Available-for-sale Dividends income 14,069 9,446 11,477 Impairment loss on available-for-sale financial assets (84,370 ) (86,703 ) (2,713 ) Gain (loss) on disposal of available-for-sale (3,004 ) 1,473 (1,213 ) Interest income 29 — — Held-to-maturity Interest income 99 97 82 Loans and receivables Interest income 28,586 25,106 30,014 Trade and other receivables Interest income 100,771 102,237 102,727 Short-term financial instruments Interest income 46,921 45,763 29,412 Long-term financial instruments Interest income 10,492 7,195 8,144 Financial assets at fair value through profit or loss Interest income — — 290 Gain (loss) on valuation of derivatives 220,285 113,671 (214,100 ) Gain (loss) on transaction of derivatives 8,605 (8,039 ) (37,266 ) Gain on valuation of financial assets — — 12 Derivative assets (using hedge accounting) Gain (loss) on valuation of derivatives (profit or loss) 244,020 145,458 (41,129 ) Gain (loss) on valuation of derivatives (equity, before tax)(*) (12,572 ) 50,047 2,453 Gain (loss) on transaction of derivatives 2,818 (13,994 ) (58,299 ) Financial liabilities carried at amortized cost Interest expense of borrowings and debt securities (1,392,477 ) (1,202,065 ) (1,240,727 ) Loss on retirement of financial liabilities (33 ) (23,000 ) (5 ) Interest expense of trade and other payables (84,527 ) (68,375 ) (57,160 ) Interest expense of others (538,680 ) (482,428 ) (491,665 ) Gain (loss) on foreign currency transactions and translations (708,178 ) (290,485 ) 1,075,215 Financial liabilities at fair value through profit or loss Gain (loss) on valuation of derivatives 35,312 23,225 (179,879 ) Gain (loss) on transaction of derivatives 107,454 17,045 (27,175 ) Derivative liabilities (using hedge accounting) Gain (loss) on valuation of derivatives (profit or loss) 93,914 5,714 (439,559 ) Gain (loss) on valuation of derivatives (equity, before tax)(*) 9,728 (3,297 ) 29,431 Loss on transaction of derivatives (4,288 ) (51,450 ) (46,221 ) (*) Items are included in other comprehensive income or loss. All other income and gain amounts listed above are included in finance income, and all expense and losses listed above are included in finance expenses in the consolidated statements of comprehensive income or loss.

Restricted Deposits (Tables)

Restricted Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Restricted Deposits [Abstract]
Restricted Deposits	Restricted deposits as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Cash and cash equivalents Escrow accounts ￦ 91 53 Deposits for government project 16,457 15,365 Collateral provided for borrowings 80,327 79,569 Collateral provided for lawsuit 241 2 Deposits for transmission regional support program 2,137 2,320 Short-term financial instruments Bidding guarantees 118 119 Restriction on withdrawal related to ‘win-win for small and medium enterprises 33,000 34,000 Other current receivables Deposit for lawsuit 16,000 — Financial assets at fair value through profit or loss Decommissioning costs of nuclear power plants — 108,512 Non-current available-for-sale Decommissioning costs of nuclear power plants 437,015 214,156 Long-term financial instruments Guarantee deposits for checking account 2 2 Guarantee deposits for banking accounts at oversea branches 342 302 Decommissioning costs of nuclear power plants 214,121 337,234 Funds for developing small and medium enterprises(*) 200,000 200,000 ￦ 999,851 991,634 (*1) Deposits for small and medium enterprise at IBK and others for construction of Bitgaram Energy Valley and support for the high potential businesses as of December 31, 2017 and 2016.

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	12 Months Ended
	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	Cash and cash equivalents as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Cash ￦ 119 132 Other demand deposits 1,725,785 968,966 Short-term deposits classified as cash equivalents 120,594 559,239 Short-term investments classified as cash equivalents 1,204,855 841,402 ￦ 3,051,353 2,369,739

Trade and Other Receivables (Ta

Trade and Other Receivables (Tables)	12 Months Ended
	Dec. 31, 2017
Trade and Other Receivables [Abstract]
Trade and Other Receivables	2016 Gross Allowance for Present value discount Book In millions of won Current assets Trade receivables ￦ 7,260,227 (71,985 ) — 7,188,242 Other receivables 652,782 (50,071 ) (2,077 ) 600,634 7,913,009 (122,056 ) (2,077 ) 7,788,876 Non-current Trade receivables 491,509 — — 491,509 Other receivables 1,455,860 (37,590 ) (6,264 ) 1,412,006 1,947,369 (37,590 ) (6,264 ) 1,903,515 ￦ 9,860,378 (159,646 ) (8,341 ) 9,692,391 2017 Gross Allowance for Present value discount Book In millions of won Current assets Trade receivables ￦ 7,499,285 (173,583 ) — 7,325,702 Other receivables 614,212 (9,199 ) (1,743 ) 603,270 8,113,497 (182,782 ) (1,743 ) 7,928,972 Non-current Trade receivables 449,191 — (414 ) 448,777 Other receivables 1,380,983 (68,809 ) (6,154 ) 1,306,020 1,830,174 (68,809 ) (6,568 ) 1,754,797 ￦ 9,943,671 (251,591 ) (8,311 ) 9,683,769
Other receivables	2016 Gross Allowance for Present value Book In millions of won Current assets Non-trade ￦ 360,021 (50,071 ) — 309,950 Accrued income 62,063 — — 62,063 Deposits 193,720 — (2,077 ) 191,643 Finance lease receivables 12,225 — — 12,225 Others 24,753 — — 24,753 652,782 (50,071 ) (2,077 ) 600,634 Non-current Non-trade 80,393 (26,942 ) — 53,451 Accrued income 174 — — 174 Deposits 320,935 — (6,264 ) 314,671 Finance lease receivables 960,649 — — 960,649 Others 93,709 (10,648 ) — 83,061 1,455,860 (37,590 ) (6,264 ) 1,412,006 ￦ 2,108,642 (87,661 ) (8,341 ) 2,012,640 2017 Gross amount Allowance for Present value Book In millions of won Current assets Non-trade ￦ 314,256 (9,199 ) — 305,057 Accrued income 54,002 — — 54,002 Deposits 228,317 — (1,743 ) 226,574 Finance lease receivables 13,067 — — 13,067 Others 4,570 — — 4,570 614,212 (9,199 ) (1,743 ) 603,270 Non-current Non-trade 112,983 (59,117 ) — 53,866 Accrued income 182 — — 182 Deposits 331,071 — (6,154 ) 324,917 Finance lease receivables 849,554 — — 849,554 Others 87,193 (9,692 ) — 77,501 1,380,983 (68,809 ) (6,154 ) 1,306,020 ￦ 1,995,195 (78,008 ) (7,897 ) 1,909,290
Aging analysis of trade receivables	2016 2017 In millions of won Trade receivables: (not overdue, not impaired) ￦ 7,592,363 7,698,604 Trade receivables: (overdue, not impaired) 820 7,117 Less than 60 days 820 7,117 Trade receivables: (impairment reviewed) 158,553 242,755 60 ~ 90 days 44,277 39,070 90 ~ 120 days 18,917 17,502 120 days ~ 1year 42,534 55,242 Over 1 year 52,825 130,941 7,751,736 7,948,476 Less: allowance for doubtful accounts (71,985 ) (173,583 ) Less: present value discount — (414 ) ￦ 7,679,751 7,774,479
Aging analysis of other receivables	2016 2017 In millions of won Other receivables: (not overdue, not impaired) ￦ 1,887,620 1,810,075 Other receivables: (overdue, not impaired) 46,887 47,532 Less than 60 days 46,887 47,532 Other receivables: (impairment reviewed) 174,135 137,588 60 ~ 90 days 7,352 44 90 ~ 120 days 2,160 1,017 120 days ~ 1year 17,613 11,042 Over 1 year 147,010 125,485 2,108,642 1,995,195 Less: allowance for doubtful accounts (87,661 ) (78,008 ) Less: present value discount (8,341 ) (7,897 ) ￦ 2,012,640 1,909,290
Changes in the allowance for doubtful accounts	2015 2016 2017 Trade Other Trade Other Trade Other In millions of won Beginning balance ￦ 80,644 67,932 51,956 91,746 71,985 87,661 Bad debt expense 1,308 18,473 38,719 233 126,714 1,778 Write-off (28,978 ) (888 ) (18,939 ) (928 ) (32,995 ) (3,129 ) Reversal (1,018 ) (413 ) — (5,489 ) — (2,166 ) Others — 6,642 249 2,099 7,879 (6,136 ) Ending balance ￦ 51,956 91,746 71,985 87,661 173,583 78,008

Available-for-sale Financial 67

Available-for-sale Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Available-for-sale Financial Assets [Abstract]
Changes in available-for-sale financial assets	available-for-sale 2016 Beginning Acquisition Disposal(*1) Valuation Impairment Others Ending In millions of won Listed ￦ 196,579 — (3,398 ) 74,139 (9,122 ) 9,973 268,171 Unlisted 387,900 449,484 (1,828 ) (12,346 ) (77,581 ) 932 746,561 584,479 449,484 (5,226 ) 61,793 (86,703 ) 10,905 1,014,732 Short-term available-for-sale — — — — — — — Long-term available-for-sale ￦ 584,479 449,484 (5,226 ) 61,793 (86,703 ) 10,905 1,014,732 (*1) The Company recognized gain and loss on disposal of available-for-sale IBK-AUCTUS 2017 Beginning Acquisition Disposal(*1) Valuation Impairment Others Ending In millions of won Listed ￦ 268,171 106 — 8,156 (97 ) (1,883 ) 274,453 Unlisted 746,561 233,179 (461,423 ) (2,908 ) (2,616 ) (87,413 ) 425,380 1,014,732 233,285 (461,423 ) 5,248 (2,713 ) (89,296 ) 699,833 Short-term available-for-sale — — — — — — — Long-term available-for-sale ￦ 1,014,732 233,285 (461,423 ) 5,248 (2,713 ) (89,296 ) 699,833 (*1) The Company recognized gain and loss on disposal of available-for-sale
Available-for-sale financial assets	2016 Shares Ownership Acquisition Book value Fair value In millions of won Listed Korea District Heating Corp. 2,264,068 19.55 % ￦ 173,201 154,183 154,183 Ssangyong Motor Co., Ltd. 38,568 0.03 % 428 304 304 Sungjee Construction. Co., Ltd. 10,530 0.01 % 49 21 21 Korea Line Corp. 18 0.00 % 1 — — Namkwang Engineering & Construction Co., Ltd. 46 0.00 % 15 — — Pumyang Construction Co., Ltd. 7 0.00 % 2 — — ELCOMTEC Co., Ltd. 32,875 0.04 % 217 74 74 PAN ocean Co., Ltd. 1,492 0.00 % 14 7 7 Borneo International Furniture Co., Ltd. 64,037 0.28 % 97 103 103 Dongbu Corporation 1,229 0.02 % 12 12 12 PT Adaro Energy Tbk 480,000,000 1.50 % 71,554 73,061 73,061 Energy Fuels Inc. 1,711,814 2.59 % 16,819 3,385 3,385 Baralaba Coal Company Limited(*6) 99,763 0.07 % 18,445 42 42 Denison Mines Corp. 58,284,000 10.93 % 84,134 36,504 36,504 Fission 3.0 300,000 0.17 % — 16 16 Fission Uranium Corp. 800,000 0.17 % 785 459 459 365,773 268,171 268,171 Unlisted(*1) K&C—Gyeongnam youth job creation Investment Fund 24 10.00 % 1,207 1,207 — Korea investment—Korea EXIM Bank CERs Private Special Assets Investment Trust I 1,758,731,002 14.18 % 1,752 571 — Troika Overseas Resource Development Private Equity Firm 13,340,012,100 3.66 % 13,340 1,553 — IBK-AUCTUS 152 6.29 % 41 41 — Global Dynasty Overseas Resource Development Private Equity Firm 2,233,407,439 7.46 % 2,233 2,233 — Intellectual Discovery, Ltd. 1,000,000 8.81 % 5,000 1,375 — Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 4,256,096,329 5.00 % 4,389 4,389 — Construction Guarantee(*2) 571 0.02 % 601 819 819 Plant & Mechanical Contractors Financial Cooperative of Korea 50 0.01 % 36 36 — Fire Guarantee 40 0.02 % 20 20 — Korea Software Financial Cooperative 5,186 1.39 % 3,301 3,301 — Engineering Financial Cooperative 486 0.05 % 60 60 — Electric Contractors Financial Cooperative 800 0.03 % 152 152 — Korea Specialty Contractor Financial Cooperative 476 0.01 % 417 417 — Information & Communication Financial Cooperative 70 0.01 % 10 10 — Korea Electric Engineers Association 400 0.24 % 40 40 — Korea investment—Investment Pool for Public funds 10(*5) — — 142,470 141,315 141,315 2016 Shares Ownership Acquisition Book value Fair value In millions of won Samsung investment—Investment Pool for Public funds 2(*5) — — ￦ 213,710 211,920 211,920 Samsung investment—Investment Pool for Public funds 1(*5) — — 53,220 53,212 53,212 Korea investment—Hanwha KT Master Lease Private Special Investment Trust(*5) — — 30,560 30,568 30,568 Hwan Young Steel Co., Ltd. 10,916 0.14 % 1,092 97 — SAMBO AUTO. Co., Ltd. 15,066 0.02 % 38 38 — Mobo Co., Ltd. 504 0.00 % 14 14 — HANKOOK Silicon Co., Ltd. 3,005,208 10.44 % 7,513 1,495 — Dae Kwang Semiconductor Co., Ltd. 589 0.07 % 6 6 — Sanbon Department Store 828 0.01 % 124 3 — Miju Steel Mfg. Co., Ltd. 99,804 0.23 % 51 51 — BnB Sungwon Co., Ltd. 589 0.07 % 15 15 — Hana Civil Engineering Co., Ltd. 23 0.00 % 1 1 — KC Development Co., Ltd. 839 0.02 % 6 6 — IMHWA Corp. 329 0.11 % 5 5 — DALIM Special Vehicle Co., Ltd. 58 0.08 % 10 10 — ASA JEONJU Co., Ltd. 34,846 1.34 % 697 69 — Moonkyung Silica Co., Ltd. 42 0.56 % — — — Sungkwang Timber Co., Ltd. 9 0.34 % 4 4 — Yongbo Co., Ltd. 61 0.20 % 3 3 — HJ Steel Co., Ltd. 218 0.07 % 2 2 — KS Remicon Co., Ltd. 12 0.04 % 3 3 — SIN-E 109 0.08 % 33 33 — Joongang Platec Co., Ltd. 3,591 0.75 % 72 35 — Pyungsan SI Ltd. 434 0.01 % 9 9 — Samgong Development Co., Ltd. 12 0.01 % 7 7 — Joongang Development Co., Ltd. 540 0.12 % 8 8 — AJS Co., Ltd. 12,906 0.23 % 32 32 — SHIN-E 119 0.13 % 10 10 — MSE Co., Ltd. 429 0.13 % 9 9 — Ilrim Nano Tec Co., Ltd. 1,520 0.07 % 15 15 — Youngjin Hi-Tech 2,512 0.25 % 126 21 — Dong Woo International Co., Ltd. 90 0.37 % 18 18 — Buyoung Co., Ltd. 270 0.00 % 3 3 — Ilsuk Co., Ltd. 152 0.17 % 10 10 — Dongyang Telecom Co., Ltd. 1,760 0.01 % 11 11 — Han Young Construction Co., Ltd. 35 0.03 % 3 3 — Jongwon Remicon Co., Ltd. 31 0.18 % 13 13 — Ace Heat Treating Co., Ltd. 477 1.43 % 72 72 — Zyle Daewoo Motor Sales Co., Ltd. 22 0.00 % — — — Daewoo Development Co., Ltd. 8 0.00 % — — — Seyang Inc. 537 0.05 % 27 27 — Seungri Enterprise Co., Ltd. 93 0.05 % 3 3 — Onggane Food Co., Ltd 5 0.07 % 1 1 — Shin-E 12 0.00 % 1 1 — Ejung Ad Co., Ltd. 132 0.09 % 3 3 — Solvus Co., Ltd. 1,056 0.04 % 3 3 — Myung Co., Ltd. 89 0.05 % 2 2 — Emotion Co., Ltd. 167 0.61 % 8 8 — Youngdong Concrete Co., Ltd. 32 0.32 % 7 7 — 2016 Shares Ownership Acquisition Book value Fair value In millions of won Shinil Engineering Co., Ltd. 887 0.06 % ￦ 3 3 — Biwang Industry Co., Ltd 406 0.04 % 2 2 — Huimun Co., Ltd. 263 0.26 % 4 4 — Young Sung Co., Ltd. 89 0.40 % 27 27 — Yuil Industrial Electronics Co., Ltd. 804 0.32 % 16 16 — DN TEK Inc. 12,401 0.29 % 62 6 — Daeyang F.M.S Corporation 593 0.40 % 23 23 — Kwang Jin Structure Co., Ltd. 3,072 0.60 % 31 31 — Woojin Industry Corporation 3 0.00 % 16 16 — Kwang Sung Industry Co., Ltd. 325 0.35 % 7 7 — Futech Mold Co., Ltd. 274 0.27 % 14 14 — Samcheonri Industrial Co., Ltd. 533 0.98 % 13 13 — Woojoo Environment Ind. Co., Ltd. 101 0.11 % 13 13 — Cheongatti Co., Ltd. 57 0.10 % 4 4 — Hyungji Esquire Co., Ltd. 55 0.02 % 22 22 — Kolmar Pharma Co., Ltd. 1,426 0.01 % 52 3 — Morado Co., Ltd. 209 0.04 % 2 2 — Myung Sung Tex Co., Ltd. 20 0.00 % 2 2 — Kwang Sung Co., Ltd. 610 0.53 % 31 31 — EverTechno. Co.,Ltd. 29,424 0.73 % 147 7 — Autowel Co.,Ltd. 260 0.38 % 13 13 — Woobang Construction Co., Ltd. 8 0.00 % 8 8 — Shin Pyung Co., Ltd. 6 0.03 % 3 3 — JMC Heavy Industries Co., Ltd. 2,724 0.10 % 27 27 — Najin Steel Co., Ltd. 37 0.06 % 5 5 — Sinkwang Industry Co., Ltd. 1,091 1.68 % 5 5 — Join Land Co., Ltd. 33 0.00 % 1 1 — Crystal Co., Ltd. 22 0.07 % 2 2 — Elephant & Friends Co., Ltd. 563 0.61 % 3 3 — Mireco Co., Ltd. 109 0.25 % 11 11 — L&K Industry Co., Ltd. 1,615 0.60 % 24 24 — JO Tech Co., Ltd. 1,263 0.62 % 25 25 — Kendae Printing Co., Ltd. 422 0.60 % 21 21 — Dauning Co., Ltd. 231 0.41 % 6 6 — Korea Trecision Co., Ltd. 22 0.45 % 5 5 — Ace Track Co., Ltd. 3,130 1.08 % 219 59 — Taebok Machinery Co., Ltd. 109 1.08 % 11 11 — Yooah Industry Co., Ltd. 130 0.02 % 13 13 — Yoo-A 105 0.20 % 11 11 — Dung Hwan Co., Ltd. 531 0.02 % 5 5 — Hurim Biocell Co., Ltd. 113 0.00 % 5 5 — P. J, Trading Co., Ltd. 12 0.04 % — — — Sunjin Power Tech Co., Ltd. 4,941 0.92 % 247 90 — Smart Power Co.,Ltd. 133,333 5.55 % 200 200 — Haseung Industries Co.,Ltd. 55 0.62 % 28 28 — Beer Yeast Korea Inc. 1,388 0.43 % 7 7 — Daeryung Corporation 207 0.19 % 10 10 — Korea Bio Red Ginseng Co.,Ltd. 194 0.09 % 10 10 — ENH Co.,Ltd. 1,086 0.19 % 54 54 — OCO Co.,Ltd. 123 0.37 % 11 11 — B CON Co.,Ltd. 96 1.16 % 6 6 — Chunil Metal Co., Ltd. 11 0.15 % 4 4 — Teakwang Tech Co., Ltd. 2,460 0.11 % 12 12 — 2016 Shares Ownership Acquisition Book value Fair value In millions of won SsangMa Machine Co., Ltd. 4 0.05 % ￦ 1 1 — SinJin Co., Ltd. 233 0.30 % 9 9 — Ace Integration Co., Ltd 93 0.09 % 21 21 — AceInti Agricultural Co., Ltd. 3 0.00 % 1 1 — KyungDong Co., Ltd. 130 0.01 % 1 1 — ChunWon Development Co., Ltd. 193 0.19 % 39 39 — WonIl Co., Ltd. 999 0.15 % 50 50 — SungLim Industrial Co., Ltd. 29 0.03 % 1 1 — DaeHa Co., Ltd. 141 0.54 % 11 11 — Korea Minerals Co., Ltd. 191 0.05 % 135 135 — HyoDong Development Co., Ltd. 119 0.15 % 24 24 — Haspe Tech Co., Ltd. 652 0.55 % 20 20 — JoHyun Co., Ltd. 350 1.56 % 18 18 — KC Co., Ltd. 5,107 0.17 % 3 3 — SeongJi Industrial Co.,Ltd. 41 0.05 % 1 1 — AREVA NC Expansion 1,077,124 13.49 % 288,443 98,472 98,472 Navanakorn Electric Co., Ltd.(*3) 8,885,600 26.93 % 17,216 18,509 — PT. Kedap Saayq 671 10.00 % 18,540 — — Set Holding(*4) 1,100,220 2.50 % 229,255 170,170 170,170 PT. Cirebon Energi Prasarana 22,420 10.00 % 2,612 2,709 — 1,040,553 746,561 706,476 ￦ 1,406,326 1,014,732 974,647 (*1) Investments in unlisted equity securities held by the Company for which a quoted market price does not exist in an active market and fair value cannot be measured reliably were measured at cost less impairment, if any. (*2) The Company has estimated the fair value of the investment in Construction Guarantee based upon the price which would be applied when the investment is returned. The Company has recognized the difference between its fair value and book value as a gain or loss on valuation of available-for-sale (*3) Although the Company holds more than 20% of the equity shares of these investments, the Company cannot exercise significant influence. (*4) The Company has estimated the fair value of Set Holding by using the discounted cash flow method and has recognized the difference between its fair value and book value as gain or loss on valuation of available-for-sale (*5) As of December 31, 2016, the Company invested in ￦437,015 million as beneficiary securities exclusively for payment of decommissioning cost of nuclear power plants. The Company has measured the fair value of the beneficiary securities based on its net asset value. (*6) The number of shares owned has changed due to the stock merge (500:1) during the year ended December 31, 2016 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won Listed Korea District Heating Corp. 2,264,068 19.55% ￦ 173,201 165,277 165,277 Ssangyong Motor Co., Ltd. 38,568 0.03% 428 197 197 Sungjee Construction. Co., Ltd. 10,530 0.01% 49 8 8 Korea Line Corp. 18 0.00% 1 — — Namkwang Engineering & Construction Co., Ltd. 46 0.00% 15 — — Pumyang Construction Co., Ltd.(*7) 35 0.00% 2 — — ELCOMTEC Co., Ltd. 32,875 0.04% 217 72 72 PAN ocean Co., Ltd. 1,492 0.00% 14 8 8 Dongbu Corporation(*6) 955 0.02% 12 10 10 KSP Co., Ltd. 6,324 0.08% 24 24 24 STX Heavy Industries Co., Ltd. 35,749 0.14% 191 165 165 PT Adaro Energy Tbk 480,000,000 1.50% 71,554 70,531 70,531 Energy Fuels Inc. 1,711,814 2.38% 16,819 3,300 3,300 Baralaba Coal Company Limited 99,763 0.07% 18,445 22 22 Denison Mines Corp. 58,284,000 10.42% 84,134 34,292 34,292 Fission 3.0 300,000 0.14% — 15 15 Fission Uranium Corp. 800,000 0.16% 785 532 532 365,891 274,453 274,453 Unlisted Korea investment—Korea EXIM Bank CERs Private Special Asset Investment Trust I 1,758,731,002 14.18% 1,752 571 — Troika Overseas Resource Development Private Equity Firm 13,340,012,100 3.66% 13,340 1,553 — IBK-AUCTUS 152 6.29% 41 41 — Global Dynasty Overseas Resource Development Private Equity Firm 2,242,437,289 7.46% 2,242 2,242 — Intellectual Discovery, Ltd. 1,000,000 8.81% 5,000 954 — Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 4,176,751,013 5.00% 4,328 4,328 — Construction Guarantee(*2) 571 0.02% 601 833 833 Plant & Mechanical Contractors Financial Cooperative of Korea 144 0.03% 126 126 — Fire Guarantee 40 0.01% 20 20 — Korea Software Financial Cooperative 5,186 1.09% 3,301 3,301 — Engineering Financial Cooperative 486 0.05% 60 60 — Electric Contractors Financial Cooperative 1,000 0.04% 216 216 — Korea Specialty Contractor Financial Cooperative 476 0.01% 417 417 — Information & Communication Financial Cooperative 121 0.02% 26 26 — Korea Electric Engineers Association 400 0.24% 40 40 — Samsung investment—Investment Pool for Public funds 1(*5) — — 53,220 53,739 53,739 Korea investment—Hanwha KT Master Lease Private Special Investment Trust(*5) — — 26,586 26,591 26,591 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won Kyobo Royal-Class Repo Plus Fixed Income 1Y 2nd (*5) — — ￦ 33,000 33,008 33,008 Kyobo Royal-Class Repo Plus Fixed Income 2Y 1st (*5) — — 50,000 50,399 50,399 Kyobo Royal-Class Repo Plus A1 ABCP 1Y (*5) — — 50,000 50,419 50,419 Hwan Young Steel Co., Ltd. 10,916 0.14% 1,092 97 — SAMBO AUTO. Co., Ltd. 15,066 0.02% 38 38 — Mobo Co., Ltd. 504 0.00% 14 14 — Dae Kwang Semiconductor Co., Ltd. 589 0.07% 6 6 — Sanbon Department Store 828 0.01% 124 3 — Miju Steel Mfg. Co., Ltd. 99,804 0.23% 50 50 — Sungwon Co., Ltd. (formerly, BnB Sungwon Co., Ltd.) 589 0.07% 15 15 — Hana Civil Engineering Co., Ltd. 23 0.00% 1 1 — KC Development Co., Ltd. 839 0.02% 6 6 — IMHWA Corp. 329 0.11% 5 5 — DALIM Special Vehicle Co., Ltd. 58 0.08% 10 10 — ASA JEONJU Co., Ltd. 34,846 1.34% 697 69 — Moonkyung Silica Co., Ltd. 42 0.56% — — — Sungkwang Timber Co., Ltd. 9 0.34% 4 4 — Yongbo Co., Ltd. 61 0.20% 3 3 — HJ Steel Co., Ltd. 218 0.07% 2 2 — KS Remicon Co., Ltd. 12 0.04% 3 3 — Joongang Platec Co., Ltd. 3,591 0.75% 72 35 — Pyungsan SI Ltd. 434 0.01% 9 9 — Samgong Development Co., Ltd. 12 0.01% 7 7 — Joongang Development Co., Ltd. 540 0.12% 8 8 — AJS Co., Ltd. 12,906 0.23% 32 32 — SHIN-E 119 0.13% 10 10 — MSE Co., Ltd. 429 0.13% 9 9 — Ilrim Nano Tec Co., Ltd. 1,520 0.07% 15 15 — Youngjin Hi-Tech 2,512 0.25% 126 21 — Buyoung Co., Ltd. 270 0.00% 3 3 — Ilsuk Co., Ltd. 152 0.17% 10 10 — Dongyang Telecom Co., Ltd. 1,760 0.01% 11 11 — Jongwon Remicon Co., Ltd. 31 0.18% 13 13 — Ace Heat Treating Co., Ltd. 477 1.43% 72 72 — Zyle Daewoo Motor Sales Co., Ltd. 22 0.00% — — — Daewoo Development Co., Ltd. 8 0.00% — — — Seyang Inc. 537 0.05% 27 27 — Seungri Enterprise Co., Ltd. 93 0.05% 3 3 — Onggane Food Co., Ltd 5 0.07% 1 1 — Shin-E 12 0.00% 1 1 — Ejung Ad Co., Ltd. 132 0.09% 3 3 — Solvus Co., Ltd. 1,056 0.04% 3 3 — Myung Co., Ltd. 89 0.05% 2 2 — Shinil Engineering Co., Ltd. 887 0.06% 3 3 — Biwang Industry Co., Ltd 406 0.04% 2 2 — Huimun Co., Ltd. 263 0.26% 4 4 — Young Sung Co., Ltd. 89 0.40% 26 26 — Yuil Industrial Electronics Co., Ltd. 804 0.32% 15 15 — DN TEK Inc. 12,401 0.29% 61 5 — 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won Kwang Jin Structure Co., Ltd. 3,072 0.60% ￦ 31 31 — Woojin Industry Corporation 3 0.00% 16 16 — Kwang Sung Industry Co., Ltd. 325 0.35% 7 7 — Futech Mold Co., Ltd. 274 0.27% 14 14 — Woojoo Environment Ind. Co., Ltd. 101 0.11% 13 13 — Cheongatti Co., Ltd. 57 0.10% 4 4 — Hyungji Esquire Co., Ltd. 55 0.02% 22 22 — Kolmar Pharma Co., Ltd. 1,426 0.01% 52 3 — Morado Co., Ltd. 209 0.04% 2 2 — Myung Sung Tex Co., Ltd. 20 0.00% 2 2 — Kwang Sung Co., Ltd. 610 0.53% 31 31 — EverTechno. Co.,Ltd. 29,424 0.73% 148 7 — Autowel Co.,Ltd. 260 0.38% 14 14 — Woobang Construction Co., Ltd. 8 0.00% 8 8 — Shin Pyung Co., Ltd. 6 0.03% 3 3 — JMC Heavy Industries Co., Ltd. 2,724 0.10% 27 27 — Najin Steel Co., Ltd. 37 0.06% 5 5 — Sinkwang Industry Co., Ltd. 1,091 1.68% 5 5 — Crystal Co., Ltd. 22 0.07% 2 2 — Elephant & Friends Co., Ltd. 563 0.61% 3 3 — Mireco Co., Ltd. 109 0.25% 11 11 — L&K Industry Co., Ltd. 1,615 0.60% 24 24 — JO Tech Co., Ltd. 1,263 0.62% 25 25 — Kendae Printing Co., Ltd. 422 0.60% 21 21 — Dauning Co., Ltd. 231 0.41% 6 6 — Korea Trecision Co., Ltd. 22 0.45% 5 5 — Ace Track Co., Ltd. 3,130 1.08% 219 59 — Taebok Machinery Co., Ltd. 109 1.08% 11 11 — Yoo-A 105 0.20% 11 11 — Dung Hwan Co., Ltd. 531 0.02% 5 5 — Hurim Biocell Co., Ltd. 113 0.00% 5 5 — Sunjin Power Tech Co., Ltd. 4,941 0.92% 247 32 — Smart Power Co.,Ltd. 133,333 4.83% 200 200 — Haseung Industries Co.,Ltd. 55 0.62% 28 28 — Beer Yeast Korea Inc. 1,388 0.43% 7 7 — Daeryung Corporation 207 0.19% 10 10 — Korea Bio Red Ginseng Co.,Ltd. 194 0.09% 10 10 — ENH Co.,Ltd. 1,086 0.19% 54 54 — B CON Co.,Ltd. 96 1.16% 6 6 — Chunil Metal Co.,Ltd. 11 0.15% 4 4 — SsangMa Machine Co., Ltd. 4 0.05% 1 1 — SinJin Co., Ltd. 233 0.30% 9 9 — Ace Integration Co., Ltd 105 0.09% 24 24 — AceInti Agricultural Co., Ltd. 16 0.02% 5 5 — KyungDong Co., Ltd. 130 0.01% 1 1 — ChunWon Development Co., Ltd. 193 0.19% 39 39 — WonIl Co., Ltd. 999 0.15% 50 50 — SungLim Industrial Co., Ltd. 29 0.03% 1 1 — Korea Minerals Co., Ltd. 191 0.05% 134 1 — HyoDong Development Co., Ltd. 119 0.15% 24 24 — Haspe Tech Co., Ltd. 652 0.55% 20 20 — JoHyun Co., Ltd. 350 1.56% 18 18 — KC Co., Ltd. 5,107 0.17% 3 3 — SeongJi Industrial Co.,Ltd. 41 0.05% 1 1 — 2017 Shares Ownership Acquisition cost Book value Fair value In millions of won DongKwang SD, Inc. 524 0.23% ￦ 13 13 — Dong Yang Metal Co., Ltd. 2,951 1.97% 15 15 — Seyang Precision Ind. Co., Ltd. 829 0.23% 41 41 — Dooriwon Food System Co., Ltd. 13 0.27% 1 1 — ShinShin Co., Ltd 339 1.12% 17 17 — Kitorang Co., Ltd. 165 0.24% 49 49 — Sung Kwang Co., Ltd. 23 0.37% 6 6 — Hyundai Metal Co., Ltd. 3,757 5.60% 1,416 1,416 — Shinheung petrol. Co. Ltd. 699 0.14% 7 7 — Force TEC Co., Ltd. 3,501 0.02% 18 18 — Haisung Industrial Systems Co., Ltd. 10,751 0.24% 54 54 — Samsung Tech Co., Ltd. 486 1.28% 97 97 — Tae Hyung Co., Ltd. 28 0.43% 20 20 — Samyangplant Co., Ltd. 323 0.60% 16 16 — Younil Metal Co., Ltd. 41 0.21% 21 21 — Myungjin Tech Co., Ltd. 20 0.54% 4 4 — Hankook Machine Tools Co., Ltd. 719 0.14% 72 72 — Hankook Precision Ind Co., Ltd. 110 0.06% 11 11 — Borneo International Furniture Co., Ltd. 64,037 0.28% 97 14 — CJ Paradise Co.,Ltd 24 0.02% 12 12 — Han Young Technology Company Co.,Ltd. 35 0.00% — — — Jungdo Aluminium Co.,Ltd. 8,527 0.35% 128 128 — Ilheung Metal Co, Ltd. 280 0.83% 28 28 — STX Offshore & Shipbuilding Co., Ltd 8,622 0.25% 1,078 1,078 — Ptotronics Co., Ltd. 151 0.07% 2 2 — NFT Co., Ltd. 136 0.40% 8 8 — Echoroba Co.,Ltd. 157 0.02% 3 3 — Hyundaitech Co.,Ltd. 1,363 0.87% 27 27 — Eco Alux Co.,Ltd. 239 0.22% 48 48 — Daekyung Industry Co.,Ltd. 9,112 0.94% 13 13 — Dasan Material Co.Ltd. 29 0.04% — — — Fish World Co.,Ltd. 47 0.21% 2 2 — SG Shinsung Engineering and Construction Co., Ltd. 10 0.00% 6 6 — Samdo Industry Electric Co.,Ltd. 48 0.02% 1 1 — Taejung Industries Co.,Ltd. 9,268 0.30% 5 5 — Shinsei Trading Co., Ltd. 64 0.72% 1 1 — Dynamic Co., Ltd. 111 0.19% 3 3 — Green Alchemy Co.,Ltd. 38,202 1.48% 191 191 — IQ Power Asia Inc. 16,179 0.31% 81 81 — Youone TBM Engineering & Construction Co., Ltd. 227,854 0.27% 31 31 — KM Leatech 1,648 0.98% 8 8 — Wonil T&I Co., Ltd. 229 0.17% 23 23 — Semist Co.,Ltd. 555 0.80% 3 3 — DS POWER Co., Ltd.(*8) 580,000 2.34% 2,900 1,223 1,223 Navanakorn Electric Co., Ltd.(*3) 4,442,800 26.93% 17,216 16,410 — PT. Kedap Saayq 671 10.00% 18,540 — — Set Holding(*4) 1,100,220 2.50% 229,255 171,242 171,242 PT. Cirebon Energi Prasarana 22,420 10.00% 2,612 2,401 — 522,782 425,380 387,454 ￦ 888,673 699,833 661,907 (*1) Investments in unlisted equity securities held by the Company for which a quoted market price does not exist in an active market and fair value cannot be measured reliably were measured at cost less impairment, if any. (*2) The Company has estimated the fair value of the investment in Construction Guarantee based upon the price which would be applied when the investment is returned. The Company has recognized the difference between its fair value and book value as a gain or loss on valuation of available-for-sale (*3) Although the Company holds more than 20% of the equity shares of these investments, the Company cannot exercise significant influence. (*4) The Company has estimated the fair value of Set Holding by using the discounted cash flow method and has recognized the difference between its fair value and book value as gain or loss on valuation of available-for-sale (*5) As of December 31, 2017, the Company invested in ￦285,769 million as beneficiary securities exclusively for payment of decommissioning cost of nuclear power plants. The Company has measured the fair value of the beneficiary securities based on its net asset value. (*6) The number of shares owned has changed due to the stock merge (9:7) during the year ended December 31, 2017. (*7) The number of shares increased due to the stock split (5:1). (*8) As described in note 17, this is reclassified to available-for-sale

Held-to-maturity Investments (T

Held-to-maturity Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Held-to-maturity Investments [Abstract]
Held-to-maturity Investments	Held-to-maturity 2016 Beginning balance Acquisition Disposal Others Ending balance In millions of won Government bonds ￦ 3,623 149 (528 ) — 3,244 ￦ 3,623 149 (528 ) — 3,244 Current ￦ 380 — (380 ) 114 114 Non-current 3,243 149 (148 ) (114 ) 3,130 2017 Beginning balance Acquisition Disposal Others Ending balance In millions of won Government bonds ￦ 3,244 250 (350 ) — 3,144 ￦ 3,244 250 (350 ) — 3,144 Current ￦ 114 — (113 ) 4 5 Non-current 3,130 250 (237 ) (4 ) 3,139

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2017
Derivatives [Abstract]
Derivatives	2016 2017 Current Non-current Current Non-current In millions of won Derivative assets Currency forward ￦ 8,370 32,806 45 — Currency swap 184,913 540,057 12 15,711 Interest rate swap — 4,705 — 2,697 Others(*1) — 10,523 12,878 1,283 ￦ 193,283 588,091 12,935 19,691 Derivative liabilities Currency forward ￦ 1,153 34 7,862 1,278 Currency swap — 56,612 61,997 296,098 Interest rate swap 2,098 78,789 1,408 59,416 ￦ 3,251 135,435 71,267 356,792 (*1) The Company has a put option to sell shares of DS POWER Co., Ltd, a related party of the Company, and the fair value of the option is recorded in ‘Others’.
Currency forward contracts which are not designated as hedge instruments	Counterparty Contract Date Maturity date Contract amounts Contract exchange rate Pay Receive In millions of won and thousands of foreign currencies KEB Hana Bank 2014.04.10 2021.07.12 55,120 USD 52,000 1,060.00 KEB Hana Bank 2014.04.28 2021.07.12 50,784 USD 48,000 1,058.00 Bank of America 2014.04.29 2021.07.12 105,400 USD 100,000 1,054.00 KEB Hana Bank 2014.05.09 2021.07.12 104,600 USD 100,000 1,046.00 KEB Hana Bank 2017.12.22 2021.07.12 105,079 USD 100,000 1,050.79 Korea Development Bank 2017.12.27 2021.07.12 104,849 USD 100,000 1,048.49 CCB 2017.12.07 2018.01.11 10,921 USD 10,000 1,092.14 Morgan Stanley 2017.11.27 2018.01.03 5,439 USD 5,000 1,087.70 Mizuho Bank 2017.11.29 2018.01.05 5,402 USD 5,000 1,080.32 KEB Hana Bank 2017.11.30 2018.01.08 5,437 USD 5,000 1,087.35 Mizuho Bank 2017.12.05 2018.01.09 5,416 USD 5,000 1,083.20 Nova Scotia 2017.12.11 2018.01.12 10,922 USD 10,000 1,092.20 Kookmin Bank 2017.12.12 2018.01.15 3,270 USD 3,000 1,090.15 Kookmin Bank 2017.12.13 2018.01.16 10,906 USD 10,000 1,090.55 Credit Suisse 2017.12.14 2018.01.17 10,858 USD 10,000 1,085.80 Standard Chartered 2017.12.14 2018.01.18 10,858 USD 10,000 1,085.80 Morgan Stanley 2017.12.15 2018.01.19 10,884 USD 10,000 1,088.39 Nova Scotia 2017.12.18 2018.01.22 10,881 USD 10,000 1,088.14 Standard Chartered 2017.12.20 2018.01.22 5,413 USD 5,000 1,082.60 Mizuho Bank 2017.12.21 2018.01.26 10,802 USD 10,000 1,080.20 Credit Suisse 2017.12.22 2018.01.26 10,778 USD 10,000 1,077.75 KEB Hana Bank 2017.12.28 2018.01.29 10,716 USD 10,000 1,071.55 CCB 2017.12.28 2018.01.30 10,706 USD 10,000 1,070.60 Nova Scotia 2017.12.29 2018.02.05 10,679 USD 10,000 1,067.90 Nova Scotia 2017.12.05 2018.01.05 2,170 USD 2,000 1,084.92 Nova Scotia 2017.12.05 2018.01.05 2,164 USD 2,000 1,082.02 Nova Scotia 2017.12.07 2018.01.05 6,551 USD 6,000 1,091.77 Korea Development Bank 2017.12.14 2018.01.10 11,950 USD 11,000 1,086.35 Societe Generale 2017.12.14 2018.01.10 10,865 USD 10,000 1,086.45 BTMU 2017.12.20 2018.01.16 11,906 USD 11,000 1,082.35 Korea Development Bank 2017.12.20 2018.01.16 15,130 USD 14,000 1,080.70 CCB 2017.12.21 2018.01.23 11,880 USD 11,000 1,080.00 Korea Development Bank 2017.12.28 2018.01.31 11,782 USD 11,000 1,071.10 Nova Scotia 2017.12.28 2018.01.23 33,209 USD 31,000 1,071.25 KEB Hana Bank 2017.12.28 2018.01.23 10,712 USD 10,000 1,071.15 BTMU 2017.12.28 2018.01.31 10,712 USD 10,000 1,071.20 BNP Paribas 2017.11.15 2018.01.17 3,713 USD 3,349 1,108.60 Nova Scotia 2017.11.15 2018.01.22 8,837 USD 8,000 1,104.60 BTMU 2017.11.29 2018.02.01 7,568 USD 7,000 1,081.20 BNP Paribas 2017.11.29 2018.02.01 7,557 USD 7,000 1,079.60 Credit Agricole 2017.12.19 2018.01.22 5,429 USD 5,000 1,085.75 BTMU 2017.12.20 2018.02.22 10,822 USD 10,000 1,082.18 KEB Hana Bank 2017.12.20 2018.01.22 2,879 USD 2,661 1,082.00 BNP Paribas 2017.12.20 2018.01.22 5,406 USD 5,000 1,081.10 Nonghyup Bank 2017.12.21 2018.01.23 6,467 USD 6,000 1,077.90 Nova Scotia 2017.12.27 2018.01.29 5,366 USD 5,000 1,073.15 Nova Scotia 2017.12.27 2018.01.05 5,373 USD 5,000 1,074.50 KEB Hana Bank 2017.11.23 2018.01.11 9,237 USD 8,500 1,086.76 Standard Chartered 2017.12.13 2018.01.15 5,454 USD 5,000 1,090.70 Standard Chartered 2017.12.08 2018.01.25 10,921 USD 10,000 1,092.05 Standard Chartered 2017.10.31 2018.02.21 5,610 USD 5,000 1,122.00 Standard Chartered 2017.11.29 2018.02.21 7,572 USD 7,000 1,081.65 Nova Scotia 2017.12.20 2018.03.22 3,978 USD 3,682 1,080.55 Nova Scotia 2017.12.20 2018.03.22 5,399 USD 5,000 1,079.75 Nova Scotia 2017.12.20 2018.03.22 5,393 USD 5,000 1,078.55 Nova Scotia 2017.12.20 2018.03.22 5,393 USD 5,000 1,078.65 Nova Scotia 2017.12.14 2018.03.19 205 USD 189 1,084.50 Standard Chartered 2017.12.19 2018.03.21 3,164 USD 2,918 1,084.20 Societe Generale 2017.12.19 2018.03.21 1,177 USD 1,087 1,082.90 Societe Generale 2017.12.19 2018.03.21 5,418 USD 5,000 1,083.60 Societe Generale 2017.12.19 2018.03.21 5,421 USD 5,000 1,084.20 BNP Paribas 2017.12.19 2018.03.21 5,413 USD 5,000 1,082.60 BNP Paribas 2017.12.19 2018.03.21 5,419 USD 5,000 1,083.70 BNP Paribas 2017.12.19 2018.03.21 5,422 USD 5,000 1,084.30 Nova Scotia 2017.12.19 2018.03.21 5,427 USD 5,000 1,085.40 Nova Scotia 2017.12.19 2018.03.21 5,430 USD 5,000 1,085.90 Nova Scotia 2017.12.14 2018.03.19 5,428 USD 5,000 1,085.50 Standard Chartered 2017.12.14 2018.03.19 5,428 USD 5,000 1,085.50 Nova Scotia 2017.11.21 2018.02.26 5,266 USD 4,826 1,091.10 Nova Scotia 2017.11.21 2018.02.26 5,461 USD 5,000 1,092.10 Nova Scotia 2017.11.15 2018.02.21 1,755 USD 1,587 1,106.10 Nova Scotia 2017.11.15 2018.02.21 5,536 USD 5,000 1,107.10 Nova Scotia 2017.11.15 2018.02.21 4,462 USD 4,027 1,108.10 Nova Scotia 2017.10.31 2018.02.06 711 USD 638 1,112.80 Nova Scotia 2017.10.31 2018.02.05 194 USD 173 1,117.80 Nova Scotia 2017.10.31 2018.02.05 5,594 USD 5,000 1,118.80 Nova Scotia 2017.10.31 2018.02.02 5,604 USD 5,000 1,120.80 Nova Scotia 2017.10.31 2018.02.02 5,599 USD 5,000 1,119.80 Nomura 2017.10.31 2018.02.02 5,602 USD 5,000 1,120.40 Credit Agricole 2017.10.31 2018.02.02 5,604 USD 5,000 1,120.70 Credit Agricole 2017.10.31 2018.02.02 5,599 USD 5,000 1,119.70 Standard Chartered 2017.10.31 2018.02.02 5,604 USD 5,000 1,120.70 Standard Chartered 2017.10.31 2018.02.02 5,393 USD 4,817 1,119.70 Societe Generale 2017.10.31 2018.02.02 861 USD 768 1,120.80 Nova Scotia 2017.10.26 2018.01.30 923 USD 822 1,123.40 BNP Paribas 2017.10.13 2018.01.18 652 USD 579 1,125.60 KEB Hana Bank 2017.11.27 2018.11.26 JPY 40,000 398 9.94
Currency swap contracts which are not designated as hedge instruments	Counterparty Contract Contract amount Contract interest rate Contract Pay Receive Pay Receive In millions of won and thousands of foreign currencies Deutsche Bank 2013~2018 110,412 JPY 10,000,000 6.21% 4.19% 11.04 IBK 2013~2018 111,800 USD 100,000 3.16% 2.79% 1,118.00 Bank of America 2013~2018 103,580 JPY 10,000,000 7.05% 4.19% 10.36 Credit Suisse 2014~2019 118,632 CHF 100,000 2.98% 1.50% 1,186.32 Standard Chartered 2014~2019 114,903 CHF 100,000 4.00% 1.50% 1,149.03 Standard Chartered 2014~2029 102,470 USD 100,000 3.14% 3.57% 1,024.70 Societe Generale 2014~2024 105,017 USD 100,000 4.92% 5.13% 1,050.17 KEB Hana Bank 2015~2024 107,970 USD 100,000 4.75% 5.13% 1,079.70 Credit Agricole 2015~2024 94,219 USD 86,920 4.85% 5.13% 1,083.97 Citibank 2012~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 JP Morgan 2012~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 Bank of America 2012~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 Shinhan Bank 2016~2022 112,930 USD 100,000 2.79% 3.00% 1,129.30 HSBC 2012~2022 111,770 USD 100,000 2.89% 3.00% 1,117.70 KEB Hana Bank 2012~2022 111,770 USD 100,000 2.87% 3.00% 1,117.70 Standard Chartered 2012~2022 111,770 USD 100,000 2.89% 3.00% 1,117.70 Deutsche Bank 2012~2022 55,885 USD 50,000 2.79% 3.00% 1,117.70 DBS 2013~2018 108,140 USD 100,000 2.63% 3M Libor+0.84% 1,081.40 DBS 2013~2018 108,140 USD 100,000 2.57% 3M Libor+0.84% 1,081.40 DBS 2013~2018 108,140 USD 100,000 2.57% 3M Libor+0.84% 1,081.40 HSBC 2013~2018 107,450 USD 100,000 3.41% 2.88% 1,074.50 Standard Chartered 2013~2018 107,450 USD 100,000 3.44% 2.88% 1,074.50 JP Morgan 2013~2018 107,450 USD 100,000 3.48% 2.88% 1,074.50 Bank of America 2014~2018 107,450 USD 100,000 3.09% 2.88% 1,074.50 Citibank 2014~2018 107,450 USD 100,000 3.09% 2.88% 1,074.50 HSBC 2014~2019 105,260 USD 100,000 2.48% 2.38% 1,052.60 Standard Chartered 2014~2019 105,260 USD 100,000 2.48% 2.38% 1,052.60 Korea Development Bank 2016~2019 105,260 USD 100,000 2.48% 2.38% 1,052.60 Nomura 2015~2025 111,190 USD 100,000 2.60% 3.25% 1,111.90 Korea Development Bank 2015~2025 111,190 USD 100,000 2.62% 3.25% 1,111.90 Woori Bank 2015~2025 55,595 USD 50,000 2.62% 3.25% 1,111.90 KEB Hana Bank 2015~2025 55,595 USD 50,000 2.62% 3.25% 1,111.90 Woori Bank 2017~2027 111,610 USD 100,000 2.25% 3.13% 1,116.10 KEB Hana Bank 2017~2027 111,610 USD 100,000 2.31% 3.13% 1,116.10 Korea Development Bank 2017~2027 111,610 USD 100,000 2.31% 3.13% 1,116.10
Currency swap contracts which are designated as hedge instruments	Currency swap contracts which are designated as hedge instruments as of December 31, 2017 are as follows: Counterparty Contract year Contract amount Contract interest rate Contract rate Pay Receive Pay Receive In millions of won and thousands of foreign currencies Citibank 2013~2018 54,570 USD 50,000 2.90% 3M Libor+1.01% 1,091.40 Standard Chartered 2013~2018 54,570 USD 50,000 2.90% 3M Libor+1.01% 1,091.40 Credit Suisse 2013~2018 111,410 USD 100,000 3.22% 3M Libor+1.50% 1,114.10 HSBC 2014~2020 99,901 AUD 100,000 3.52% 5.75% 999.01 HSBC 2014~2020 100,482 AUD 100,000 3.48% 5.75% 1,004.82 Standard Chartered 2013~2020 USD 117,250 AUD 125,000 3M Libor+1.25% 5.75% 0.94 Standard Chartered 2014~2020 126,032 USD 117,250 3.55% 3M Libor+1.25% 1,074.90 Korea Development Bank 2017~2020 114,580 USD 100,000 1.75% 2.38% 1,145.80 KEB Hana Bank 2017~2020 114,580 USD 100,000 1.75% 2.38% 1,145.80 Export-import bank of Korea 2017~2020 114,580 USD 100,000 1.75% 2.38% 1,145.80 JP Morgan 2014~2019 107,190 USD 100,000 3M Libor+3.25% 2.75% 1,071.90 Morgan Stanley 2014~2019 107,190 USD 100,000 3M Libor+3.25% 2.75% 1,071.90 Deutsche Bank 2014~2019 107,190 USD 100,000 3M Libor+3.25% 2.75% 1,071.90 Korea Development Bank 2016~2021 121,000 USD 100,000 2.15% 2.50% 1,210.00 Morgan Stanley 2016~2021 121,000 USD 100,000 3M Libor+2.10% 2.50% 1,210.00 BNP Paribas 2016~2021 121,000 USD 100,000 3M Libor+2.10% 2.50% 1,210.00 Nomura 2017~2037 52,457 EUR 40,000 2.60% 1.70% 1,311.42 Nomura 2017~2037 59,423 SEK 450,000 2.62% 2.36% 132.05 Credit Agricole 2013~2019 118,343 CHF 100,000 3.47% 1.63% 1,183.43 Morgan Stanley 2013~2019 59,172 CHF 50,000 3.40% 1.63% 1,183.43 Nomura 2013~2019 59,172 CHF 50,000 3.47% 1.63% 1,183.43 Morgan Stanley 2013~2018 107,360 USD 100,000 3.27% 2.88% 1,073.60 Credit Agricole 2013~2018 107,360 USD 100,000 3.34% 2.88% 1,073.60 JP Morgan 2013~2018 161,040 USD 150,000 3.34% 2.88% 1,073.60 Standard Chartered 2013~2018 161,040 USD 150,000 3.34% 2.88% 1,073.60 Standard Chartered 2014~2019 104,490 USD 100,000 2.77% 2.63% 1,044.90 Credit Agricole 2014~2019 104,490 USD 100,000 2.77% 2.63% 1,044.90 Morgan Stanley 2014~2019 104,490 USD 100,000 2.70% 2.63% 1,044.90 Standard Chartered 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Credit Agricole 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Deutsche Bank 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Citibank 2013~2018 81,188 USD 75,000 2.65% 1.88% 1,082.50 Societe Generale 2013~2018 106,190 USD 100,000 3.48% 2.63% 1,061.90 BNP Paribas 2013~2018 53,095 USD 50,000 3.48% 2.63% 1,061.90 KEB Hana Bank 2013~2018 53,095 USD 50,000 3.48% 2.63% 1,061.90 Standard Chartered 2013~2018 106,030 USD 100,000 3.48% 2.63% 1,060.30 BNP Paribas 2013~2018 53,015 USD 50,000 3.48% 2.63% 1,060.30 KEB Hana Bank 2013~2018 31,809 USD 30,000 3.48% 2.63% 1,060.30 Societe Generale 2013~2018 21,206 USD 20,000 3.48% 2.63% 1,060.30 HSBC 2013~2018 53,015 USD 50,000 3.47% 2.63% 1,060.30 Nomura 2013~2018 53,015 USD 50,000 3.47% 2.63% 1,060.30 Credit Agricole 2014~2020 110,680 USD 100,000 2.29% 2.50% 1,106.80 Societe Generale 2014~2020 55,340 USD 50,000 2.16% 2.50% 1,106.80 KEB Hana Bank 2014~2020 55,340 USD 50,000 2.16% 2.50% 1,106.80 KEB Hana Bank 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 Standard Chartered 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 HSBC 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 Nomura 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 BNP Paribas 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 HSBC 2014~2020 55,340 USD 50,000 2.21% 2.50% 1,106.80 KEB Hana Bank 2017~2022 226,600 USD 200,000 1.94% 2.63% 1,133.00 Korea Development Bank 2017~2022 113,300 USD 100,000 1.94% 2.63% 1,133.00 Nomura 2017~2022 113,300 USD 100,000 1.95% 2.63% 1,133.00 Woori Bank 2017~2022 56,650 USD 50,000 1.95% 2.63% 1,133.00 Kookmin Bank 2017~2022 56,650 USD 50,000 1.95% 2.63% 1,133.00
Interest rate swap contracts which are not designated as hedge instruments	Counterparty Contract Contract amount Contract interest rate per annum Pay Receive In millions of JP Morgan 2013~2018 ￦ 150,000 3.58% 3M CD+0.31% Credit Suisse 2014~2018 25,000 2.98% 1Y CMT+0.31% KEB Hana Bank 2017~2022 100,000 2.01% 3M CD+0.24% KEB Hana Bank 2017~2022 100,000 2.06% 3M CD+0.27% Nomura(*1) 2017~2037 30,000 2.05% 3.08% KEB Hana Bank 2017~2021 200,000 2.45% 3M CD+0.32% Export-import bank of Korea 2015~2031 USD 15,893 2.67% 6M USD Libor ING Bank 2015~2031 USD 7,861 2.67% 6M USD Libor BNP Paribas 2015~2031 USD 7,861 2.67% 6M USD Libor (*1) 2.05% of the contract interest rate for paying is applied for five years from the date of issuance, and 3M CD + 0.10% is applied thereafter.
Interest rate swap contracts which are designated as hedge instruments	Counterparty Contract Contract amount Contract interest rate per annum Pay Receive In millions of BNP Paribas 2009~2027 USD 92,120 4.16% 6M USD Libor KFW 2009~2027 USD 92,120 4.16% 6M USD Libor Credit Agricole 2016~2033 USD 96,297 3.98% ~ 4.10% 6M USD Libor SMBC 2016~2033 USD 125,927 4.05% ~ 4.18% 6M USD Libor Mizuho Bank 2016~2019 USD 36,890 1.56% 1.35% SMBC 2016~2019 USD 36,890 1.56% 1.35%
Gain and loss on valuation and transaction of derivatives	Net income effects of valuation gain (loss) Net income effects of transaction gain (loss) Accumulated other comprehensive 2015 2016 2017 2015 2016 2017 2015 2016 2017 In millions of won Currency forward ￦ 357 15,993 (41,889 ) 8,523 4,266 (28,223 ) — — — Currency swap 431,565 253,035 (843,747 ) 75,752 (68,266 ) (137,376 ) (6,926 ) 40,031 26,810 Interest rate swap 161,609 8,517 6,909 30,314 7,562 (3,362 ) 4,082 6,719 5,074 Other derivatives — 10,523 4,060 — — — — — — ￦ 593,531 288,068 (874,667 ) 114,589 (56,438 ) (168,961 ) (2,844 ) 46,750 31,884 (*) For the year ended December 31, 2017, the net gain on valuation of derivatives applying cash flow hedge accounting of ￦20,868 million, net of tax, is included in other comprehensive income or loss.

Other Financial Assets (Tables)

Other Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Other Financial Assets [Abstract]
Other Financial Assets	2016 2017 Current Non-current Current Non-current In millions of won Loans and receivables ￦ 198,133 683,353 244,309 711,069 Allowance for doubtful accounts — (4,532 ) — (8,948 ) Present value discount (1,001 ) (41,746 ) (976 ) (39,813 ) Long / short-term financial instruments 2,281,460 414,466 1,702,084 542,430 Financial assets at fair value through profit or loss — — — 111,512 ￦ 2,478,592 1,051,541 1,945,417 1,316,250
Loans and receivables	2016 Face value Allowance for Present value Book value In millions of won Short-term loans and receivables Loans for tuition ￦ 29,028 — (1,001 ) 28,027 Loans for housing 12,556 — — 12,556 Fisheries loan 352 — — 352 Other loans 156,197 — — 156,197 198,133 — (1,001 ) 197,132 Long-term loans and receivables Loans for tuition 404,200 — (41,593 ) 362,607 Loans for housing 125,850 — — 125,850 Loans for related parties 91,249 (4,532 ) — 86,717 Fisheries loan 1,312 — (153 ) 1,159 Other loans 60,742 — — 60,742 683,353 (4,532 ) (41,746 ) 637,075 ￦ 881,486 (4,532 ) (42,747 ) 834,207 2017 Face value Allowance for Present value discount Book value In millions of won Short-term loans and receivables Loans for tuition ￦ 33,763 — (976 ) 32,787 Loans for housing 14,126 — — 14,126 Fisheries loan 352 — — 352 Other loans 196,068 — — 196,068 244,309 — (976 ) 243,333 Long-term loans and receivables Loans for tuition 408,803 — (39,716 ) 369,087 Loans for housing 140,452 — — 140,452 Loans for related parties 94,581 (8,948 ) — 85,633 Fisheries loan 960 — (97 ) 863 Other loans 66,273 — — 66,273 711,069 (8,948 ) (39,813 ) 662,308 ￦ 955,378 (8,948 ) (40,789 ) 905,641
Changes in the allowance for doubtful accounts of loans and receivables	2017 In millions of won Beginning balance ￦ 4,532 Bad debt expense 2,465 Other 1,951 Ending balance ￦ 8,948
Long-term and short-term financial instruments	2016 2017 Current Non-current Current Non-current In millions of won Time deposits ￦ 1,820,391 30,000 1,479,034 2 ABCP 351,800 132,600 145,000 65,600 CP 16,000 — 58,050 — CD 60,443 — 10,000 — RP — 1,521 10,000 1,634 Others 32,826 250,345 — 475,194 ￦ 2,281,460 414,466 1,702,084 542,430

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Inventories [Abstract]
Inventories	Inventories as of December 31, 2016 and 2017 are as follows: 2016 Acquisition cost Valuation allowance Book value In millions of won Raw materials ￦ 3,182,711 (1,323 ) 3,181,388 Merchandise 20 — 20 Work-in-progress 118,640 — 118,640 Finished goods 57,659 — 57,659 Supplies 1,289,160 (4,553 ) 1,284,607 Inventories in transit 827,437 — 827,437 Other inventories 9,692 — 9,692 ￦ 5,485,319 (5,876 ) 5,479,443 2017 Acquisition cost Valuation allowance Book value In millions of won Raw materials ￦ 3,528,835 (2,829 ) 3,526,006 Merchandise 107 — 107 Work-in-progress 138,709 (1,028 ) 137,681 Finished goods 72,923 (1,517 ) 71,406 Supplies 1,581,661 (3,940 ) 1,577,721 Inventories in transit 679,358 — 679,358 Other inventories 9,807 — 9,807 ￦ 6,011,400 (9,314 ) 6,002,086

Finance Lease Receivables (Tabl

Finance Lease Receivables (Tables)	12 Months Ended
	Dec. 31, 2017
Finance Lease Receivables [Abstract]
Finance Lease Receivables	non-current 2016 2017 Minimum lease Present value of Minimum lease Present value In millions of won Less than 1 year ￦ 55,708 12,225 49,542 13,067 1 ~ 5 years 423,152 214,176 381,181 203,990 More than 5 years 1,690,492 746,473 1,398,449 645,564 ￦ 2,169,352 972,874 1,829,172 862,621

Non-Financial Assets (Tables)

Non-Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Non-Financial Assets [Abstract]
Non-Financial Assets	Non-financial 2016 2017 Current Non-current Current Non-current In millions of won Advance payment ￦ 93,279 71,238 109,743 43,872 Prepaid expenses 228,142 78,066 251,715 90,118 Others(*1) 310,439 32,485 392,534 112,828 ￦ 631,860 181,789 753,992 246,818 (*1) Details of others as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Tax refund receivables ￦ 30,959 2,188 89,762 1,940 Greenhouse gas emissions rights 145,105 — 135,211 — Other quick assets(*2) 134,375 30,297 167,561 110,888 ￦ 310,439 32,485 392,534 112,828 (*2) The Company has recognized ￦92,128 million of shares in Orano Expansion (formerly, AREVA NC Expansion) as non-current non-financial

Consolidated Subsidiaries (Tabl

Consolidated Subsidiaries (Tables)	12 Months Ended
	Dec. 31, 2017
Consolidated Subsidiaries [Abstract]
Consolidated Subsidiaries	Consolidated subsidiaries as of December 31, 2016 and 2017 are as follows: Percentage of ownership (%) Subsidiaries Key operation activities Location 2016 2017 Korea Hydro & Nuclear Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea South-East Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea Midland Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea Western Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea Southern Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % Korea East-West Power Co., Ltd. Power generation KOREA 100.00 % 100.00 % KEPCO Engineering & Construction Company, Inc.(*1) Architectural engineering for utility plant and others KOREA 65.77 % 65.77 % KEPCO Plant Service & Engineering Co., Ltd. Utility plant maintenance and others KOREA 51.00 % 51.00 % KEPCO Nuclear Fuel Co., Ltd. Nuclear fuel KOREA 96.36 % 96.36 % KEPCO KDN Co., Ltd. Electric power information technology and others KOREA 100.00 % 100.00 % Garolim Tidal Power Plant Co., Power generation KOREA 49.00 % 49.00 % KEPCO International HongKong Ltd. Holding company HONG KONG 100.00 % 100.00 % KEPCO International Philippines Inc. Holding company PHILIPPINES 100.00 % 100.00 % KEPCO Gansu International Ltd. Holding company HONG KONG 100.00 % 100.00 % KEPCO Philippines Holdings Inc. Holding company PHILIPPINES 100.00 % 100.00 % KEPCO Philippines Corporation Operation of utility plant PHILIPPINES 100.00 % 100.00 % KEPCO Ilijan Corporation Construction and operation of utility plant PHILIPPINES 51.00 % 51.00 % KEPCO Lebanon SARL Operation of utility plant LEBANON 100.00 % 100.00 % KEPCO Neimenggu International Ltd. Holding company HONG KONG 100.00 % 100.00 % KEPCO Shanxi International Ltd. Holding company HONG KONG 100.00 % 100.00 % KOMIPO Global Pte Ltd. Holding company SINGAPORE 100.00 % 100.00 % KEPCO Canada Energy Ltd. Resources development CANADA 100.00 % 100.00 % KEPCO Netherlands B.V. Holding company NETHERLANDS 100.00 % 100.00 % KOREA Imouraren Uranium Investment Corp. Holding company FRANCE 100.00 % 100.00 % KEPCO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOSEP Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOMIPO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOWEPO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KOSPO Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % KEPCO Middle East Holding Company Holding company BAHRAIN 100.00 % 100.00 % Qatrana Electric Power Company Construction and operation of utility plant JORDAN 80.00 % 80.00 % KHNP Canada Energy, Ltd. Holding company CANADA 100.00 % 100.00 % KEPCO Bylong Australia Pty., Ltd. Resources development AUSTRALIA 100.00 % 100.00 % Korea Waterbury Uranium Limited Partnership Resources development CANADA 79.64 % 79.64 % Korea Electric Power Nigeria Ltd. Operation of utility plant NIGERIA 100.00 % 100.00 % KEPCO Holdings de Mexico Holding company MEXICO 100.00 % 100.00 % KST Electric Power Company Construction and operation of utility plant MEXICO 56.00 % 56.00 % KEPCO Energy Service Company Operation of utility plant MEXICO 100.00 % 100.00 % KEPCO Netherlands S3 B.V. Holding company NETHERLANDS 100.00 % 100.00 % PT. KOMIPO Pembangkitan Jawa Bali Operation of utility plant INDONESIA 51.00 % 51.00 % PT. Cirebon Power Service(*2) Operation of utility plant INDONESIA 27.50 % 27.50 % KOWEPO International Corporation Operation of utility plant PHILIPPINES 99.99 % 99.99 % KOSPO Jordan LLC Operation of utility plant JORDAN 100.00 % 100.00 % EWP Philippines Corporation Holding company PHILIPPINES 100.00 % 100.00 % EWP America Inc. Holding company USA 100.00 % 100.00 % EWP Renewable Corporation Holding company USA 100.00 % 100.00 % DG Fairhaven Power, LLC Power generation USA 100.00 % 100.00 % DG Whitefield, LLC Power generation USA 100.00 % 100.00 % Springfield Power, LLC Power generation USA 100.00 % 100.00 % KNF Canada Energy Limited Holding company CANADA 96.36 % 96.36 % PT KEPCO Resource Indonesia Holding company INDONESIA 100.00 % 100.00 % EWP Barbados 1 SRL Holding company BARBADOS 100.00 % 100.00 % California Power Holdings, LLC Power generation USA 100.00 % 100.00 % Gyeonggi Green Energy Co., Ltd. Power generation KOREA 62.01 % 62.01 % PT. Tanggamus Electric Power Power generation INDONESIA 52.50 % 52.50 % Gyeongju Wind Power Co., Ltd. Power generation KOREA 70.00 % 70.00 % KOMIPO America Inc. Holding company USA 100.00 % 100.00 % EWPRC Biomass Holdings, LLC Holding company USA 100.00% 100.00% KOSEP USA, INC. Power generation USA 100.00% 100.00% PT. EWP Indonesia Holding company INDONESIA 99.95% 99.96% KEPCO Netherlands J3 B.V. Holding company NETHERLANDS 100.00% 100.00% Korea Offshore Wind Power Co., Ltd. Power generation KOREA 100.00% 100.00% Global One Pioneer B.V. Holding company NETHERLANDS 100.00% 100.00% Global Energy Pioneer B.V. Holding company NETHERLANDS 100.00% 100.00% Mira Power Limited(*3) Power generation PAKISTAN 76.00% 76.00% KOSEP Material Co., Ltd.(*4) Recycling fly ashes KOREA 46.22% 86.22% Commerce and Industry Energy Power generation KOREA 59.03% 59.03% KEPCO Singapore Holdings Pte., Ltd. Holding company SINGAPORE 100.00% 100.00% KOWEPO India Private Limited Holding company INDIA 100.00% 100.00% KEPCO KPS Philippines Corp. Utility plant maintenance and others PHILIPPINES 51.00% 51.00% KOSPO Chile SpA Holding company CHILE 100.00% 100.00% PT. KOWEPO Sumsel Operation And Maintenance Services Utility plant maintenance and others INDONESIA 95.00% 95.00% HeeMang Sunlight Power Co., Ltd. Operation of utility plant KOREA 100.00% 100.00% Fujeij Wind Power Company Operation of utility plant JORDAN 100.00% 100.00% KOSPO Youngnam Power Co., Ltd. Operation of utility plant KOREA 50.00% 50.00% HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) Holding company KOREA 96.67% 96.67% Chitose Solar Power Plant LLC Power generation JAPAN 80.10% 80.10% KEPCO Energy Solution Co. Ltd. Energy service KOREA 100.00% 100.00% Solar School Plant Co., Ltd. Power generation KOREA 100.00% 100.00% KOSPO Power Services Limitada Utility plant maintenance and others CHILE 65.00% 65.00% Energy New Industry Specialized Investment Private Investment Trust Holding company KOREA 99.75% 99.75% KOEN Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOMIPO Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOWEPO Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOSPO Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% EWP Bylong Pty., Ltd. Resources development AUSTRALIA 100.00% 100.00% KOWEPO Lao International Utility plant maintenance and others LAOS 100.00% 100.00% KEPCO US Inc. Holding company USA — 100.00% KEPCO Alamosa LLC Holding company USA — 50.10% Cogentrix Solar Services, LLC Holding company USA — 50.10% Solar Investments I, LLC Holding company USA — 50.10% Cogentrix of Alamosa, LLC Power generation USA — 50.10% KEPCO-LG Holding company USA — 70.00% Mangilao Investment LLC Holding company USA — 70.00% KEPCO-LG Power generation USA — 70.00% Jeju Hanlim Offshore Wind Co., Ltd. Power generation KOREA — 70.22% PT. Siborpa Eco Power Construction and operation of utility plant INDONESIA — 64.71% BSK E-New Holding company KOREA — 81.47% e-New Holding company KOREA — 75.92% Songhyun e-New Holding company KOREA — 80.45% (*1) Considering treasury stocks, the effective percentage of ownership is 66.08%. (*2) These subsidiaries are included in the consolidated financial statements as the Company obtained the majority of the voting power through the shareholders’ agreement. (*3) As of reporting date, the annual reporting period of all subsidiaries is December 31, except for Mira Power Limited which is November 30. (*4) The effective percentage of ownership has increased to 86.22% since Long Lasting Value exercised the put option to sell its investment to KOSEP during the year ended December 31, 2017. (*5) The Company guarantees a certain return on investment related to Commerce and Industry Energy Co., Ltd. for the financial investors. The financial investors have a right to sell their shares to the Company which can be exercised 84 months after the date of investment. Accordingly, the purchase price including the return on investment is classified as a liability.
Subsidiaries newly included in or excluded from consolidation	Subsidiaries included in consolidation during the year ended December 31, 2017. Subsidiary Reason KEPCO US Inc. Newly established KEPCO Alamosa LLC Newly established Cogentrix Solar Services, LLC Newly established Solar Investments I, LLC Newly established Cogentrix of Alamosa, LLC Newly established KEPCO-LG Newly established Mangilao Investment LLC Newly established KEPCO-LG Newly established Jeju Hanlim Offshore Wind Co., Ltd. Newly established PT. Siborpa Eco Power Newly established BSK E-New Newly established e-New Newly established Songhyun e-New Newly established There are no subsidiaries excluded from consolidation during the year ended December 31, 2017.
Summary of financial information of consolidated subsidiaries	Summary of financial information of consolidated subsidiaries as of and for the years ended December 31, 2016 and 2017 are as follows: 2016 Subsidiaries Total assets Total liabilities Sales Profit (loss) for the period In millions of won Korea Hydro & Nuclear Power Co., Ltd. ￦ 52,782,915 27,366,938 11,168,579 2,454,810 Korea South-East Power Co., Ltd. 9,773,778 4,794,330 5,093,598 531,061 Korea Midland Power Co., Ltd. 9,066,666 5,416,336 3,719,981 400,696 Korea Western Power Co., Ltd. 9,810,714 5,866,916 4,169,712 401,936 Korea Southern Power Co., Ltd. 9,806,023 5,637,950 4,200,035 426,337 Korea East-West Power Co., Ltd. 8,967,951 4,488,911 4,210,898 467,603 KEPCO Engineering & Construction Company, Inc. 786,596 364,676 506,012 17,796 KEPCO Plant Service & Engineering Co., Ltd. 1,086,421 301,490 1,214,304 86,657 KEPCO Nuclear Fuel Co., Ltd. 713,230 346,012 309,911 33,115 KEPCO KDN Co., Ltd. 519,901 205,869 588,160 43,127 Garolim Tidal Power Plant Co., Ltd. 632 346 — -24 KEPCO International HongKong Ltd. 173,138 41 — 4,532 KEPCO International Philippines Inc. 114,141 1,468 — 56,783 KEPCO Gansu International Ltd. 17,928 557 — (18 ) KEPCO Philippines Holdings Inc. 125,100 27 — 13,517 KEPCO Philippines Corporation 13,704 8,949 — (8,717 ) KEPCO Ilijan Corporation 558,030 58,449 116,667 51,552 KEPCO Lebanon SARL 1,458 10,312 — 810 KEPCO Neimenggu International Ltd. 186,636 — — 7,082 KEPCO Shanxi International Ltd. 549,189 218,047 — 5,812 KOMIPO Global Pte Ltd. 223,082 1,095 — 36,764 KEPCO Canada Energy Ltd. 202 24 — (27,216 ) KEPCO Netherlands B.V. 128,014 35 — 224 KOREA Imouraren Uranium Investment Corp. 154,302 764 — (68,417 ) KEPCO Australia Pty., Ltd. 503,657 1,545 3,670 (19,006 ) KOSEP Australia Pty., Ltd. 25,174 521 5,357 4,028 KOMIPO Australia Pty., Ltd. 25,413 10 5,388 4,023 KOWEPO Australia Pty., Ltd. 25,550 10 5,357 4,012 KOSPO Australia Pty., Ltd. 25,625 10 5,357 4,033 KEPCO Middle East Holding Company 128,846 125,008 — 6,840 Qatrana Electric Power Company 546,123 417,800 18,866 19,601 KHNP Canada Energy, Ltd. 54,374 46 — (6,304 ) KEPCO Bylong Australia Pty., Ltd. 220,721 277,358 — (2,357 ) Korea Waterbury Uranium Limited Partnership 20,882 149 — 2,348 Korea Electric Power Nigeria Ltd. 696 493 9,794 35 KEPCO Holdings de Mexico 262 19 — 251 KST Electric Power Company 596,823 539,459 146,295 17,322 KEPCO Energy Service Company 1,309 310 5,337 580 KEPCO Netherlands S3 B.V. 55,609 54 — 3,731 PT. KOMIPO Pembangkitan Jawa Bali 16,246 4,549 21,632 8,989 PT. Cirebon Power Service 3,456 1,228 7,463 301 KOWEPO International Corporation — — — — KOSPO Jordan LLC 11,524 687 7,321 317 EWP Philippines Corporation 1,966 955 — (41 ) EWP America Inc.(*) 104,809 80,252 33,616 (8,704 ) KNF Canada Energy Limited 1,967 20 — (46 ) PT KEPCO Resource Indonesia 913 18 — (341 ) EWP Barbados 1 SRL 267,859 425 1,656 (902 ) Gyeonggi Green Energy Co., Ltd. 301,126 221,078 108,557 19,211 PT. Tanggamus Electric Power 184,861 167,641 40,903 2,041 Gyeongju Wind Power Co., Ltd. ￦ 76,569 49,293 6,413 1,269 KOMIPO America Inc. 11,518 2,432 — (2,240 ) KOSEP USA, INC. 159 39,028 3,791 (72,817 ) PT. EWP Indonesia 2,154 50 — 1,088 KEPCO Netherlands J3 B.V. 125,337 68 — 12,433 Korea Offshore Wind Power Co., Ltd. 37,826 2,048 — (4,960 ) Global One Pioneer B.V. 161 22 — (54 ) Global Energy Pioneer B.V. 338 22 — (59 ) Mira Power Limited 178,141 133,730 — (954 ) KOSEP Material Co., Ltd. 2,398 1,497 3,232 (901 ) Commerce and Industry Energy Co., Ltd. 99,432 87,316 28,375 (536 ) KEPCO Singapore Holdings Pte., Ltd. 2,568 13 — (33 ) KOWEPO India Private Limited 879 — — 1 KEPCO KPS Philippines Corp. 7,897 1,213 12,843 2,060 KOSPO Chile SpA 6,656 4,787 — 125 PT. KOWEPO Sumsel Operation and Maintenance Services 1,439 700 6,165 (96 ) HeeMang Sunlight Power Co., Ltd. 7,102 3,391 12 (308 ) Fujeij Wind Power Company 47,935 46,636 — (873 ) KOSPO Youngnam Power Co., Ltd. 284,368 205,680 — (931 ) HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) 3,002 — — 9 Chitose Solar Power Plant LLC 49,728 38,806 — (811 ) KEPCO Energy Solution Co. Ltd. 299,933 233 — (300 ) Solar School Plant Co., Ltd. 200,268 259 1 9 KOSPO Power Services Limitada 4,385 1,262 7,300 2,963 Energy New Industry Specialized Investment Private Investment Trust 501,275 33 — (7 ) KOEN Bylong Pty., Ltd. 6,135 — — — KOMIPO Bylong Pty., Ltd. 6,135 — — — KOWEPO Bylong Pty., Ltd. 6,135 — — — KOSPO Bylong Pty., Ltd. 6,135 — — — EWP Bylong Pty., Ltd. 6,135 — — — KOWEPO Lao International 218 181 — (108 ) (*) Financial information of EWP America Inc. includes that of six other subsidiaries, EWP Renewable Co., DG Fairhaven Power, LLC, DG Whitefield, LLC, Springfield Power, LLC, California Power Holdings, LLC, and EWPRC Biomass Holdings, LLC. 2017 Subsidiaries Total assets Total liabilities Sales Profit (loss) for the period In millions of won Korea Hydro & Nuclear Power Co., Ltd. ￦ 55,011,096 29,252,816 9,415,751 854,346 Korea South-East Power Co., Ltd. 9,879,577 4,844,184 5,387,846 130,371 Korea Midland Power Co., Ltd. 9,893,822 6,148,173 4,167,009 104,591 Korea Western Power Co., Ltd. 9,660,426 5,739,534 4,199,079 110,939 Korea Southern Power Co., Ltd. 9,648,741 5,401,216 4,397,552 98,817 Korea East-West Power Co., Ltd. 8,855,518 4,204,187 4,644,330 217,599 KEPCO Engineering & Construction Company, Inc. 762,166 305,134 490,193 21,222 KEPCO Plant Service & Engineering Co., Ltd. 1,195,086 294,689 1,232,113 135,482 KEPCO Nuclear Fuel Co., Ltd. 792,187 421,088 279,664 4,557 KEPCO KDN Co., Ltd. 524,520 155,715 619,470 48,968 Garolim Tidal Power Plant Co., Ltd. 619 345 — (12 ) KEPCO International HongKong Ltd. 153,529 1 — 4,380 KEPCO International Philippines Inc. 102,323 886 — 47,201 KEPCO Gansu International Ltd. 11,567 493 — (29 ) KEPCO Philippines Holdings Inc. 127,922 2,621 — 43,218 KEPCO Philippines Corporation 6,293 114 — 2,098 KEPCO Ilijan Corporation 474,624 57,801 109,183 66,320 KEPCO Lebanon SARL 1,069 9,281 — (219 ) KEPCO Neimenggu International Ltd. 165,937 — — 500 KEPCO Shanxi International Ltd. 497,990 193,309 — 3,796 KOMIPO Global Pte Ltd. 225,411 1,497 — 21,858 KEPCO Canada Energy Ltd. 132 22 — (32 ) KEPCO Netherlands B.V. 114,911 49 — 17,309 KOREA Imouraren Uranium Investment Corp. 151,278 131 — 1,490 KEPCO Australia Pty., Ltd. 466,654 569 — (568 ) KOSEP Australia Pty., Ltd. 27,076 333 12,096 1,601 KOMIPO Australia Pty., Ltd. 31,441 4,691 12,096 1,133 KOWEPO Australia Pty., Ltd. 31,586 4,691 12,096 1,232 KOSPO Australia Pty., Ltd. 29,472 4,221 12,096 (2,759 ) KEPCO Middle East Holding Company 95,812 90,842 — 2,913 Qatrana Electric Power Company 460,206 327,401 18,892 23,310 KHNP Canada Energy, Ltd. 51,994 31 — (92 ) KEPCO Bylong Australia Pty., Ltd. 242,364 277,549 — 20,271 Korea Waterbury Uranium Limited Partnership 20,886 136 — (59 ) Korea Electric Power Nigeria Ltd. 238 76 2,164 29 KEPCO Holdings de Mexico 235 30 — (20 ) KST Electric Power Company 546,242 478,230 120,126 16,154 KEPCO Energy Service Company 1,793 451 6,773 976 KEPCO Netherlands S3 B.V. 46,642 53 — 2,382 PT. KOMIPO Pembangkitan Jawa Bali 11,261 4,769 20,956 4,666 PT. Cirebon Power Service 2,808 155 7,439 592 KOWEPO International Corporation — 8 — (2 ) KOSPO Jordan LLC 24,077 13,594 7,331 953 EWP Philippines Corporation 1,708 836 — (17 ) EWP America Inc.(*1) 79,854 67,308 23,543 (9,737 ) KNF Canada Energy Limited 1,884 31 — (43 ) PT KEPCO Resource Indonesia 491 — — (311 ) EWP Barbados 1 SRL 235,096 450 — (2,585 ) Gyeonggi Green Energy Co., Ltd. 282,408 199,160 95,192 3,203 PT. Tanggamus Electric Power 179,317 160,144 34,281 4,640 Gyeongju Wind Power Co., Ltd. 112,279 82,124 7,219 2,400 KOMIPO America Inc. 10,505 521 — 2,071 KOSEP USA, INC. 184 9,065 — 26,997 2017 Subsidiaries Total assets Total liabilities Sales Profit (loss) for the period In millions of won PT. EWP Indonesia ￦ 2,035 23 — 1,916 KEPCO Netherlands J3 B.V. 122,612 76 — 12,115 Korea Offshore Wind Power Co., Ltd. 190,195 1,985 — (6,997 ) Global One Pioneer B.V. 151 38 — (80 ) Global Energy Pioneer B.V. 309 41 — (87 ) Mira Power Limited 208,150 163,198 — 737 KOSEP Material Co., Ltd. 2,751 1,448 3,128 320 Commerce and Industry Energy Co., Ltd. 99,129 87,926 30,577 (749 ) KEPCO Singapore Holdings Pte., Ltd. 3,265 4 — (24 ) KOWEPO India Private Limited 781 — — (46 ) KEPCO KPS Philippines Corp. 6,636 235 6,840 555 KOSPO Chile SpA 133,570 50,109 — 1,066 PT. KOWEPO Sumsel Operation And Maintenance Services 1,350 279 7,651 659 HeeMang Sunlight Power Co., Ltd. 6,876 3,395 105 (229 ) Fujeij Wind Power Company 165,636 156,099 — 8,836 KOSPO Youngnam Power Co.,Ltd. 412,785 333,302 68,973 939 HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) 3,002 — — 12 Chitose Solar Power Plant LLC 136,098 121,622 7,083 4,100 KEPCO Energy Solution Co. Ltd. 313,401 12,376 5,544 1,325 Solar School Plant Co., Ltd. 201,482 599 67 874 KOSPO Power Services Limitada 3,901 887 11,067 666 Energy New Industry Specialized Investment Private Investment Trust(*3) 506,207 2,118 — 52 KOEN Bylong Pty., Ltd. 5,875 — — — KOMIPO Bylong Pty., Ltd. 5,875 — — — KOWEPO Bylong Pty., Ltd. 5,875 — — — KOSPO Bylong Pty., Ltd. 5,875 — — — EWP Bylong Pty., Ltd. 5,875 — — — KOWEPO Lao International 3,259 1,452 3,624 1,881 KEPCO US Inc. 16,913 — — — KEPCO Alamosa LLC 33,144 492 — (218 ) Cogentrix Solar Services, LLC(*2) 84,458 53,116 8,958 (112 ) KEPCO-LG 24,131 24,395 — (278 ) Mangilao Investment LLC 24,131 — — — KEPCO-LG 24,002 134 — (278 ) Jeju Hanlim Offshore Wind Co., Ltd. 36 — — — PT. Siborpa Eco Power 11,562 214 — (518 ) (*1) Financial information of EWP America Inc. includes that of six other subsidiaries, EWP Renewable Corporation, DG Fairhaven Power, LLC, DG Whitefield, LLC, Springfield Power, LLC, California Power Holdings, LLC, and EWPRC Biomass Holdings, LLC. (*2) Financial information of Cogentrix Solar Services, LLC includes that of two other subsidiaries, Solar Investments I, LLC and Cogentrix of Alamosa, LLC. (*3) Financial information of Energy New Industry Specialized Investment Private Investment Trust includes that of three other subsidiaries, BSK E-New e-New e-New
Significant restrictions on abilities to subsidiaries	Company Nature and extent of any significant restrictions Gyeonggi Green Energy Co., Ltd. Acquisition or disposal of assets of more than ￦35 billion, change in the capacity of cogeneration units (except for the change due to performance improvement of equipment, maintenance) will require unanimous consent of all directors. KOSPO Youngnam Power Co., Ltd. Dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Shares cannot be wholly or partially transferred without prior written consent of financial institutions.
Details of non-controlling interest prior to intra-group eliminations	non-controlling 2016 Description KEPCO KEPCO Plant KEPCO Construction Others Total In millions of won Percentage of ownership 49.00 % 49.00 % 33.92 % Current assets ￦ 154,758 553,924 270,553 1,211,510 2,190,745 Non-current 403,272 532,497 516,043 2,379,882 3,831,694 Current liabilities (19,256 ) (264,506 ) (286,444 ) (297,510 ) (867,716 ) Non-current (39,193 ) (36,984 ) (78,232 ) (1,919,924 ) (2,074,333 ) Net assets 499,581 784,931 421,920 1,373,958 3,080,390 Book value of non-controlling 244,794 384,616 143,115 684,093 1,456,618 Sales 116,667 1,214,304 506,012 674,461 2,511,444 Profit for the period 51,552 86,657 17,796 102,170 258,175 Profit for the period attributable to non-controlling 25,260 42,462 6,036 26,709 100,467 Cash flows from operating activities 102,546 121,240 18,748 84,086 326,620 Cash flows from investing activities (117 ) 79,807 (7,556 ) (367,674 ) (295,540 ) Cash flows from financing activities before dividends to non-controlling (56,863 ) (39,911 ) (1,634 ) 877,863 779,455 Dividends to non-controlling (55,705 ) (36,139 ) (2,539 ) (22,054 ) (116,437 ) Effect of exchange rate fluctuation 1,529 127 (854 ) 7,216 8,018 Net increase (decrease) of cash and cash equivalents (8,610 ) 125,124 6,165 579,437 702,116 2017 Description KEPCO Ilijan KEPCO Plant KEPCO Construction Others Total In millions of won Percentage of ownership 49.00 % 49.00 % 33.92 % Current assets ￦ 160,588 623,934 257,529 1,269,175 2,311,226 Non-current 314,036 571,152 504,637 2,588,833 3,978,658 Current liabilities (21,546 ) (278,562 ) (221,860 ) (394,320 ) (916,288 ) Non-current (36,255 ) (16,127 ) (83,274 ) (2,014,925 ) (2,150,581 ) Net assets 416,823 900,397 457,032 1,448,763 3,223,015 Book value of non-controlling 204,243 441,194 155,025 612,245 1,412,707 Sales 109,183 1,232,113 490,193 719,087 2,550,576 Profit for the period 66,320 135,482 21,222 66,419 289,443 Profit for the period attributable to non-controlling 32,497 66,386 7,199 20,447 126,529 Cash flows from operating activities 123,534 129,801 62,578 60,021 375,934 Cash flows from investing activities (5,276 ) (193,408 ) (8,622 ) (409,353 ) (616,659 ) Cash flows from financing activities before dividends to non-controlling (44,442 ) (15,606 ) (55,504 ) 339,432 223,880 Dividends to non-controlling (48,855 ) (14,994 ) (1,419 ) (20,840 ) (86,108 ) Effect of exchange rate fluctuation (7,432 ) (1,267 ) (101 ) (24,206 ) (33,006 ) Net increase (decrease) of cash and cash equivalents 17,529 (95,474 ) (3,068 ) (54,946 ) (135,959 )
Changes in goodwill	Details of goodwill as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Acquisition cost ￦ 2,582 2,582 Accumulated impairment — — Carrying book value ￦ 2,582 2,582
Disposals of subsidiaries	KEPCO Canada Uranium Investment Limited Partnership was dissolved and the Company liquidated DG Kings Plaza, LLC during the year ended December 31, 2016. (i) The fair value of proceeds from disposal as of December 31, 2016 is as follows: 2016 In millions of won Cash received upon dissolution ￦ 898 Net assets transferred due to dissolution 34,148 ￦ 35,046 (ii) The carrying value of assets and liabilities of subsidiaries as at the date the Company lost its control during the year ended December 31, 2016 are as follows: 2016 In millions of won Current assets Cash and cash equivalents ￦ 898 Current financial assets, net 81 Non-current Available-for-sale 34,089 Current liabilities Current financial liabilities (22 ) ￦ 35,046 (iii) Gain from disposals of subsidiaries for the year ended December 31, 2016 is as follows: 2016 In millions of won Fair value of sale price ￦ 35,046 Net assets disposed (35,046 ) Non-controlling — Realization of unrealized gain — Other comprehensive income — Gain from disposals of subsidiaries ￦ — (iv) Net cash flow from sales of subsidiaries for the year ended December 31, 2016 is as follows: 2016 In millions of won Consideration received in cash ￦ 898 Less: cash held by disposed subsidiaries (898 ) Net cash flow ￦ —
Cash dividends received from subsidiaries	Cash dividends received from subsidiaries for the years ended December 31, 2015, 2016 and 2017, respectively, are as follows: Subsidiaries 2015 2016 2017 In millions of won Korea Hydro & Nuclear Power Co., Ltd. ￦ 446,399 635,200 543,072 Korea South-East Power Co., Ltd. 57,485 124,169 106,546 Korea Midland Power Co., Ltd. 16,580 23,073 54,305 Korea Western Power Co., Ltd. 22,749 36,238 66,992 Korea Southern Power Co., Ltd. 10,272 17,849 60,630 Korea East-West Power Co., Ltd. 25,280 67,906 94,430 KEPCO Engineering & Construction Company, Inc. 14,574 5,069 2,765 KEPCO Plant Service & Engineering Co., Ltd. 40,584 39,911 15,607 KEPCO Nuclear Fuel Co., Ltd. 6,280 3,411 3,231 KEPCO KDN Co., Ltd. 4,046 3,392 4,352 KEPCO International HongKong Ltd. 25,826 9,107 4,304 KEPCO International Philippines Inc. 32,891 61,862 44,906 KEPCO Ilijan Corporation 38,128 57,979 50,849 KEPCO Philippines Holdings Inc. 19,221 17,747 26,023 KEPCO Neimenggu International Ltd. 25,338 10,735 — KOMIPO Global Pte Ltd. — 10,432 — Qatrana Electric Power Company 16,857 8,331 5,939 KOSPO Jordan LLC — 1,095 — KEPCO Energy Service Company — 294 — EWP Philippines Corporation 5,586 — — KEPCO Netherlands S3 B.V. 1,382 — — PT. KOMIPO Pembangkitan Jawa Bali 3,169 3,222 3,188 KEPCO Netherlands J3 B.V. 19,254 12,507 — Gyeongju Wind Power Co., Ltd. 1,294 679 — Energy New Industry Specialized Investment Private Investment Trust — — 291 HI Carbon Professional Private Special Asset Investment Trust 1 (formerly, Global One Carbon Private Equity Investment Trust 2) — — 11 KOSPO Power Services Limitada — — 425 Cogentrix Solar Services, LLC — — 344 ￦ 833,195 1,150,208 1,088,210

Investments in Associates and75

Investments in Associates and Joint Ventures (Tables)	12 Months Ended
	Dec. 31, 2017
Investments in Associates and Joint Ventures [Abstract]
Investments in Associates and Joint Ventures	2016 Investees Key operation activities Location Percentage of Acquisition cost Book value In millions of won <Associates> Korea Gas Corporation(*1) Importing and wholesaling LNG KOREA 20.47 % ￦ 94,500 1,933,877 Korea Electric Power Industrial Development Co., Ltd. Electricity metering and others KOREA 29.00 % 4,727 20,475 YTN Co., Ltd. Broadcasting KOREA 21.43 % 59,000 38,156 Cheongna Energy Co., Ltd. Generating and distributing vapor and hot/cold water KOREA 43.90 % 48,353 12,373 Gangwon Wind Power Co., Ltd.(*2) Power generation KOREA 15.00 % 5,725 13,069 Hyundai Green Power Co., Ltd. Power generation KOREA 29.00 % 88,885 115,998 Korea Power Exchange(*6) Management of power market and others KOREA 100.00 % 127,839 223,238 AMEC Partners Korea Ltd.(*3) Resources development KOREA 19.00 % 707 225 Hyundai Energy Co., Ltd.(*9) Power generation KOREA 30.66 % 71,070 1,031 Ecollite Co., Ltd. Artificial light-weight aggregate KOREA 36.10 % 1,516 — Taebaek Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,810 4,750 Taeback Guinemi Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,420 3,131 Pyeongchang Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,875 3,383 Daeryun Power Co., Ltd.(*3, 10) Power generation KOREA 13.13 % 25,477 29,873 Changjuk Wind Power Co., Ltd. Power generation KOREA 30.00 % 3,801 6,930 KNH Solar Co., Ltd. Power generation KOREA 27.00 % 1,296 2,073 SPC Power Corporation Power generation PHILIPPINES 38.00 % 20,635 56,818 Gemeng International Energy Co., Ltd. Power generation CHINA 34.00 % 413,153 680,065 PT. Cirebon Electric Power Power generation INDONESIA 27.50 % 40,365 96,658 KNOC Nigerian East Oil Co., Resources development NIGERIA 14.63 % 12 — KNOC Nigerian West Oil Co., Resources development NIGERIA 14.63 % 12 — PT Wampu Electric Power Power generation INDONESIA 46.00 % 21,292 23,188 PT. Bayan Resources TBK Resources development INDONESIA 20.00 % 615,860 402,667 S-Power Power generation KOREA 49.00 % 132,300 123,912 Pioneer Gas Power Limited(*8) Power generation INDIA 40.00 % 49,831 50,740 Eurasia Energy Holdings Power generation and resources development RUSSIA 40.00 % 461 — Xe-Pian Xe-Namnoy Power generation LAOS 25.00 % 49,119 51,544 Hadong Mineral Fiber Co., Ltd.(*17) Recycling fly ashes KOREA 8.33 % 50 — Green Biomass Co., Ltd.(*12) Power generation KOREA 14.00 % 714 47 PT. Mutiara Jawa Manufacturing and operating floating coal terminal INDONESIA 29.00 % 2,978 — Samcheok Eco Materials Co., Recycling fly ashes KOREA 2.35 % 686 — Noeul Green Energy Co., Ltd. Power generation KOREA 29.00 % 1,740 1,217 Naepo Green Energy Co., Ltd. Power generation KOREA 25.00 % 29,200 25,438 Goseong Green Energy Co., Ltd.(*2) Power generation KOREA 1.12 % 2,900 2,663 Gangneung Eco Power Co., Ltd.(*2) Power generation KOREA 1.61 % 2,900 2,646 Shin Pyeongtaek Power Co., Ltd. Power generation KOREA 40.00 % 40 — Heang Bok Do Si Photovoltaic Power Co., Ltd. Power generation KOREA 28.00 % 194 181 DS POWER Co., Ltd.(*2) Power generation KOREA 14.44 % 17,900 7,190 Dongducheon Dream Power Co., Ltd. Power generation KOREA 33.61 % 61,535 46,876 KS Solar Co., Ltd.(*3) Power generation KOREA 19.00 % 637 604 Yeongwol Energy Station Co., Power generation KOREA 10.00 % 1,400 — Jinbhuvish Power Generation Pvt. Power generation INDIA 5.16 % ￦ 9,000 — SE Green Energy Co., Ltd. Power generation support KOREA 47.76 % 3,821 3,525 Daegu Photovoltaic Co., Ltd. Power generation KOREA 29.00 % 1,230 1,700 Jeongam Wind Power Co., Ltd. Power generation KOREA 40.00 % 5,580 4,000 Korea Power Engineering Service Co., Ltd. Construction and service KOREA 29.00 % 290 2,810 Busan Green Energy Co., Ltd. Power generation KOREA 29.00 % 14,564 13,803 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.)(*2) Power generation KOREA 18.87 % 1,000 — Korea Electric Vehicle Charging Service Electric vehicle charge service KOREA 28.00 % 1,596 1,103 Ulleungdo Natural Energy Co., Ltd. Renewable power generation KOREA 29.85 % 8,000 6,894 Korea Nuclear Partners Co., Ltd. Electric material agency KOREA 29.00 % 290 248 Tamra Offshore Wind Power Co., Ltd. Power generation KOREA 27.00 % 8,910 7,015 Korea Electric Power Corporation Developing electric enterprises KOREA 98.09 % 51,500 50,856 Energy Infra Asset Management Co., Ltd.(*3) Asset management KOREA 9.90 % 297 259 Daegu clean Energy Co., Ltd. Renewable power generation KOREA 28.00 % 140 140 YaksuESS Co., Ltd Installing ESS related equipment KOREA 29.00 % 210 196 Nepal Water & Energy Development Company Private Limited(*14) Construction and operation of utility plant NEPAL 52.77 % 18,568 18,667 2,134,911 4,092,252 <Joint ventures> KEPCO-Uhde Inc.(*7) Power generation KOREA 52.8 % 11,355 301 Eco Biomass Energy Sdn. Bhd.(*7) Power generation MALAYSIA 61.53 % 9,661 — Datang Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 27,660 28,239 Shuweihat Asia Power Investment B.V. Holding company NETHERLANDS 49.00 % 46,037 — Shuweihat Asia Operation & Maintenance Company(*7) Maintenance of utility plant CAYMAN 55.00 % 30 450 Waterbury Lake Uranium L.P. Resources development CANADA 36.97 % 26,602 21,314 ASM-BG Power generation BULGARIA 50.00 % 16,101 21,488 RES Technology AD Power generation BULGARIA 50.00 % 15,595 13,582 KV Holdings, Inc. Power generation PHILIPPINES 40.00 % 2,103 2,098 KEPCO SPC Power Corporation(*7) Construction and operation of utility plant PHILIPPINES 75.20 % 94,579 245,367 Canada Korea Uranium Limited Partnership(*5) Resources development CANADA 12.50 % 5,404 — Gansu Datang Yumen Wind Power Co., Ltd. Power generation CHINA 40.00 % 16,621 12,821 Datang Chifeng Renewable Power Co., Ltd. Power generation CHINA 40.00 % 121,928 166,535 Datang KEPCO Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 10,858 10,843 Rabigh Electricity Company Power generation SAUDI ARABIA 40.00 % 109,743 97,802 Rabigh Operation & Maintenance Company Limited Maintenance of utility plant SAUDI ARABIA 40.00 % 70 4,427 Jamaica Public Service Company Limited Power generation JAMAICA 40.00 % 301,910 249,453 KW Nuclear Components Co., Ltd. Manufacturing KOREA 45.00 % 833 7,133 Busan Shinho Solar Power Co., Ltd. Power generation KOREA 25.00 % 2,100 3,814 GS Donghae Electric Power Co., Ltd. Power generation KOREA 34.00 % 204,000 205,948 Global Trade Of Power System Co., Ltd. Exporting products and technology of small or medium business by proxy KOREA 29.00 % ￦ 290 477 Expressway Solar-light Power Generation Co., Ltd. Power generation KOREA 29.00 % 1,856 2,343 KODE NOVUS I LLC Power generation USA 50.00 % 19,213 — KODE NOVUS II LLC Power generation USA 50.00 % 12,756 — Daejung Offshore Wind Power Co., Ltd. Power generation KOREA 49.90 % 4,990 3,015 Amman Asia Electric Power Power generation JORDAN 60.00 % 111,476 153,857 KAPES, Inc.(*7) R&D KOREA 51.00 % 5,629 4,758 Dangjin Eco Power Co., Ltd. Power generation KOREA 34.00 % 56,100 53,253 Honam Wind Power Co., Ltd. Power generation KOREA 29.00 % 3,480 4,451 Chun-cheon Energy Co., Ltd. Power generation KOREA 29.90 % 52,700 50,592 Yeonggwangbaeksu Wind Power Co., Ltd.(*3) Power generation KOREA 15.00 % 3,000 2,689 Nghi Son 2 Power Ltd. Power generation VIETNAM 50.00 % 1,788 229 Kelar S.A(*7) Power generation CHILE 65.00 % 4,180 — PT. Tanjung Power Indonesia Power generation INDONESIA 35.00 % 746 1,946 Incheon New Power Co., Ltd. Power generation KOREA 29.00 % 461 563 Seokmun Energy Co., Ltd. Power generation KOREA 29.00 % 580 391 Daehan Wind Power PSC Power generation JORDAN 50.00 % 285 16 Barakah One Company(*16) Power generation UAE 18.00 % 118 116 Nawah Energy Company(*16) Operation of utility plant UAE 18.00 % 296 290 MOMENTUM International thermonuclear experimental reactor construction management FRANCE 33.33 % 1 67 Daegu Green Power Co., Ltd.(*15) Power generation KOREA 29.00 % 46,225 47,528 1,349,360 1,418,196 ￦ 3,484,271 5,510,448 (*1) The effective percentage of ownership is 21.57% considering treasury stocks. (*2) The Company can exercise significant influence by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors. (*3) The Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity. (*4) The Company can exercise significant influence by virtue of its contractual right to appoint one out of four members of the steering committee of the entity. Moreover, the Company has significant financial transactions, which can affect its influence on the entity. (*5) The Company has joint control over the entity by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors. (*6) The Government regulates the Company’s ability to make operating and financial decisions over the entity, as the Government requires maintaining arms-length transactions between KPX and the Company’s other subsidiaries. The Company can exercise significant influence by its right to nominate directors to the board of directors of the entity. (*7) According to the shareholders’ agreement, all critical financial and operating decisions must be agreed to by all ownership parties. For these reasons, the entities are classified as joint ventures. (*8) As of reporting date, the annual reporting period of all associates and joint ventures ends on December 31, except for Pioneer Gas Power Limited whose reporting period ends on March 31. (*9) As of December 31, 2016, 15.64% of ownership of Hyundai Energy Co., Ltd. is held by NH Power ll Co., Ltd. and NH Bank. According to the shareholders’ agreement reached on March 2011, not only does the Company have a call option to acquire the investment in Hyundai Energy Co., Ltd. from NH Power ll Co., Ltd. and NH Bank with a certain rate of return, NH Power ll Co., Ltd. and NH Bank also have put options to dispose of their investment to the Company. In connection with this agreement, the Company applied the equity method on the investment in Hyundai Energy Co., Ltd. with 46.30% of ownership. (*10) The Company’s percentage of ownership has decreased due to the acquisition of Daeryun Power Co., Ltd. and the effective percentage of ownership is 19.45% considering stock purchase options. (*11) The Company’s effective percentage of ownership excluding the redeemable convertible preferred stock is 25.54%. (*12) The effective percentage of ownership is less than 20% but the Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity and the fact that the dominant portion of the investee’s sales transactions is generated from the Company. (*13) The effective percentage of ownership is more than 50% but the Company does not hold control over relevant business while it exercises significant influence by participating in the Investment Decision Committee. For this reason, the entity is classified as an associate. (*14) The effective percentage of ownership is more than 50%, but the Company does not control the entity according to the shareholders’ agreement. For this reason, the entity is classified as an associate. (*15) The entity is reclassified from associates to joint ventures since the terms of the shareholders’ agreement had been amended. (*16) The effective percentage of ownership is less than 20%, but the Company has joint control over the entity as decisions on the major activities require the unanimous consent of the parties that collectively control the entity. (*17) Although the percentage of ownership temporarily decreased to 8.33% from the difference in timing of capital payment by shareholders, the Company can exercise significant influence by virtue of its right to appoint a director to the board of directors of the entity based on the shareholders’ agreement. The percentage of ownership is 25.00% at the time of completion of capital payment. 2017 Investees Key operation activities Location Percentage of Acquisition Book In millions of won <Associates> Korea Gas Corporation(*1) Importing and wholesaling LNG KOREA 20.47 % ￦ 94,500 1,618,868 Korea Electric Power Industrial Development Co., Ltd. Electricity metering and others KOREA 29.00 % 4,727 21,838 YTN Co., Ltd. Broadcasting KOREA 21.43 % 59,000 40,606 Cheongna Energy Co., Ltd. Generating and distributing vapor and hot/cold water KOREA 43.90 % 48,353 8,337 Gangwon Wind Power Co., Ltd.(*2) Power generation KOREA 15.00 % 5,725 13,855 Hyundai Green Power Co., Ltd. Power generation KOREA 29.00 % 88,885 114,806 Korea Power Exchange(*5) Management of power market and others KOREA 100.00 % 127,839 237,631 AMEC Partners Korea Ltd.(*3) Resources development KOREA 19.00 % 707 215 Hyundai Energy Co., Ltd.(*8) Power generation KOREA 30.66 % 71,070 — Ecollite Co., Ltd. Artificial light-weight aggregate KOREA 36.10 % 1,516 — Taebaek Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,810 5,319 Taeback Guinemi Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,420 3,089 Pyeongchang Wind Power Co., Ltd. Power generation KOREA 25.00 % 3,875 4,136 Daeryun Power Co., Ltd.(*3, 9) Power generation KOREA 13.13 % 25,477 25,113 Changjuk Wind Power Co., Ltd. Power generation KOREA 30.00 % 3,801 7,515 KNH Solar Co., Ltd. Power generation KOREA 27.00 % 1,296 2,218 SPC Power Corporation Power generation PHILIPPINES 38.00 % 20,635 52,283 Gemeng International Energy Co., Ltd. Power generation CHINA 34.00 % 413,153 649,973 PT. Cirebon Electric Power Power generation INDONESIA 27.50 % 40,365 97,410 KNOC Nigerian East Oil Co., Ltd.(*4) Resources development NIGERIA 14.63 % 12 — KNOC Nigerian West Oil Co., Ltd.(*4) Resources development NIGERIA 14.63 % 12 — PT Wampu Electric Power Power generation INDONESIA 46.00 % 21,292 29,403 PT. Bayan Resources TBK Resources development INDONESIA 20.00 % 615,860 451,831 S-Power Power generation KOREA 49.00 % 132,300 116,945 Pioneer Gas Power Limited(*7) Power generation INDIA 38.50 % 49,831 38,659 Eurasia Energy Holdings Power generation and resources development RUSSIA 40.00 % 461 — Xe-Pian Xe-Namnoy Power generation LAOS 25.00 % 71,481 61,779 Hadong Mineral Fiber Co., Ltd.(*3) Recycling fly ashes KOREA 8.33 % 50 — Green Biomass Co., Ltd.(*11, 14) Power generation KOREA 8.80 % 714 208 PT. Mutiara Jawa Manufacturing and operating floating coal terminal INDONESIA 29.00 % 2,978 — Samcheok Eco Materials Co., Ltd.(*10) Recycling fly ashes KOREA 2.35 % 686 — Noeul Green Energy Co., Ltd. Power generation KOREA 29.00 % 1,740 2,067 Naepo Green Energy Co., Ltd. Power generation KOREA 41.67 % ￦ 29,200 20,598 Goseong Green Energy Co., Ltd.(*2) Power generation KOREA 1.12 % 2,900 2,597 Gangneung Eco Power Co., Ltd.(*2) Power generation KOREA 1.61 % 2,900 2,583 Shin Pyeongtaek Power Co., Ltd. Power generation KOREA 40.00 % 43,920 34,903 Heang Bok Do Si Photovoltaic Power Co., Ltd. Power generation KOREA 28.00 % 194 187 Dongducheon Dream Power Co., Ltd. Power generation KOREA 33.61 % 111,134 53,233 Jinbhuvish Power Generation Pvt. Power generation INDIA 5.16 % 9,000 — SE Green Energy Co., Ltd. Power generation KOREA 47.76 % 3,821 3,476 Daegu Photovoltaic Co., Ltd. Power generation KOREA 29.00 % 1,230 1,718 Jeongam Wind Power Co., Ltd. Power generation KOREA 40.00 % 5,580 3,763 Korea Power Engineering Service Co., Ltd. Construction and service KOREA 29.00 % 290 3,659 Busan Green Energy Co., Ltd. Power generation KOREA 29.00 % 5,243 7,363 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.)(*2) Power generation KOREA 18.87 % 1,000 — Korea Electric Vehicle Charging Service Electric vehicle charge service KOREA 28.00 % 2,604 1,749 Ulleungdo Natural Energy Co., Ltd. Renewable power generation KOREA 29.85 % 8,000 6,370 Korea Nuclear Partners Co., Ltd. Electric material agency KOREA 29.00 % 290 383 Tamra Offshore Wind Power Co., Ltd. Power generation KOREA 27.00 % 8,910 8,560 Korea Electric Power Corporation Fund(*12) Developing electric enterprises KOREA 98.09 % 51,500 47,974 Energy Infra Asset Management Co., Ltd.(*3) Asset management KOREA 9.90 % 297 476 Daegu clean Energy Co., Ltd. Renewable power generation KOREA 28.00 % 140 11 YaksuESS Co., Ltd Installing ESS related equipment KOREA 29.00 % 210 194 Nepal Water & Energy Development Company Private Limited(*15) Construction and operation of utility plant NEPAL 62.13 % 33,577 30,498 Gwangyang Green Energy Co., Ltd. Power generation KOREA 20.00 % 2,000 1,772 PND solar., Ltd Power generation KOREA 29.00 % 1,250 1,250 2,240,761 3,837,421 <Joint ventures> KEPCO-Uhde Inc.(*6) Power generation KOREA 52.80 % 11,355 258 Eco Biomass Energy Sdn. Bhd.(*6) Power generation MALAYSIA 61.53 % 14,439 — Datang Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 27,660 27,262 Shuweihat Asia Power Investment B.V. Holding company NETHERLANDS 49.00 % 46,037 15,675 Shuweihat Asia Operation & Maintenance Company(*6) Maintenance of utility plant CAYMAN 55.00 % 30 663 Waterbury Lake Uranium L.P. Resources development CANADA 35.76 % 26,602 19,781 ASM-BG Power generation BULGARIA 50.00 % 16,101 21,202 RES Technology AD Power generation BULGARIA 50.00 % 15,595 14,375 KV Holdings, Inc. Power generation PHILIPPINES 40.00 % 2,103 1,918 KEPCO SPC Power Corporation(*6) Construction and operation of utility plant PHILIPPINES 75.20 % 94,579 217,094 Gansu Datang Yumen Wind Power Co., Ltd. Power generation CHINA 40.00 % 16,621 10,840 Datang Chifeng Renewable Power Co., Ltd. Power generation CHINA 40.00 % 121,928 171,055 Datang KEPCO Chaoyang Renewable Power Co., Ltd. Power generation CHINA 40.00 % 10,858 11,060 Rabigh Electricity Company Power generation SAUDI ARABIA 40.00 % 109,743 99,356 Rabigh Operation & Maintenance Company Limited Maintenance of utility plant SAUDI ARABIA 40.00 % 70 3,987 Jamaica Public Service Company Limited Power generation JAMAICA 40.00 % ￦ 301,910 221,153 KW Nuclear Components Co., Ltd. Manufacturing KOREA 45.00 % 833 6,703 Busan Shinho Solar Power Co., Ltd. Power generation KOREA 25.00 % 2,100 4,346 GS Donghae Electric Power Co., Ltd. Power generation KOREA 34.00 % 204,000 220,727 Global Trade Of Power System Co., Ltd. Exporting products and technology of small or medium business by proxy KOREA 29.00 % 290 577 Expressway Solar-light Power Generation Co., Ltd. Power generation KOREA 29.00 % 1,856 2,463 KODE NOVUS I LLC Power generation USA 50.00 % 19,213 — KODE NOVUS II LLC Power generation USA 50.00 % 12,756 — Daejung Offshore Wind Power Co., Ltd. Power generation KOREA 49.90 % 5,190 2,969 Amman Asia Electric Power Power generation JORDAN 60.00 % 111,476 145,676 KAPES, Inc.(*6) R&D KOREA 51.00 % 5,629 7,476 Dangjin Eco Power Co., Ltd. Power generation KOREA 34.00 % 61,540 57,928 Honam Wind Power Co., Ltd. Power generation KOREA 29.00 % 3,480 4,302 Chun-cheon Energy Co., Ltd. Power generation KOREA 29.90 % 52,700 48,118 Yeonggwangbaeksu Wind Power Co., Ltd.(*3) Power generation KOREA 15.00 % 3,000 2,734 Nghi Son 2 Power Ltd. Power generation VIETNAM 50.00 % 2,781 183 Kelar S.A(*6) Power generation CHILE 65.00 % 77,220 67,233 PT. Tanjung Power Indonesia Power generation INDONESIA 35.00 % 746 1,776 Incheon New Power Co., Ltd. Power generation KOREA 29.00 % 461 619 Seokmun Energy Co., Ltd. Power generation KOREA 29.00 % 15,370 13,786 Daehan Wind Power PSC Power generation JORDAN 50.00 % 285 — Barakah One Company(*13) Power generation UAE 18.00 % 118 626 Nawah Energy Company(*13) Operation of utility plant UAE 18.00 % 296 258 MOMENTUM International thermonuclear experimental reactor construction management FRANCE 33.33 % 1 391 Daegu Green Power Co., Ltd. Power generation KOREA 29.00 % 46,225 42,391 Yeonggwang Wind Power Co., Ltd. Power generation KOREA 41.00 % 15,375 15,294 Chester Solar IV SpA(*6) Power generation CHILE 81.82 % 1,700 1,700 Chester Solar V SpA(*6) Power generation CHILE 81.82 % 525 525 Diego de Almagro Solar SpA(*6) Power generation CHILE 81.82 % 2,091 2,091 South Jamaica Power Company Limited Power generation JAMAICA 20.00 % 7,090 6,704 1,469,978 1,493,275 ￦ 3,710,739 5,330,696 (*1) The effective percentage of ownership is 21.57% considering treasury stocks. (*2) The Company can exercise significant influence by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors. (*3) The Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity. (*4) The Company can exercise significant influence by virtue of its contractual right to appoint one out of four members of the steering committee of the entity. Moreover, the Company has significant financial transactions, which can affect its influence on the entity. (*5) The Government regulates the Company’s ability to make operating and financial decisions over the entity, as the Government requires maintaining arms-length transactions between KPX and the Company’s other subsidiaries. The Company can exercise significant influence by its right to nominate directors to the board of directors of the entity. (*6) According to the shareholders’ agreement, all critical financial and operating decisions must be agreed to by all ownership parties. For these reasons, the entities are classified as joint ventures. (*7) As of reporting date, the annual reporting period of all associates and joint ventures ends on December 31, except for Pioneer Gas Power Limited whose reporting period ends on March 31. (*8) As of December 31, 2017, 15.64% of ownership of Hyundai Energy Co., Ltd. is held by NH Power ll Co., Ltd. and NH Bank. According to the shareholders’ agreement reached on March 2011, not only does the Company have a call option to acquire the investment in Hyundai Energy Co., Ltd. from NH Power ll Co., Ltd. and NH Bank with a certain rate of return, NH Power ll Co., Ltd. and NH Bank also have put options to dispose of their investment to the Company. In connection with this agreement, the Company applied the equity method on the investment in Hyundai Energy Co., Ltd. with 46.30% of ownership. (*9) The Company’s percentage of ownership has decreased due to the acquisition of Daeryun Power Co., Ltd. and the effective percentage of ownership is 19.45% considering stock purchase options. (*10) The Company’s effective percentage of ownership excluding the redeemable convertible preferred stock is 25.54%. (*11) The effective percentage of ownership is less than 20% but the Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity and the fact that the dominant portion of the investee’s sales transactions is generated from the Company. (*12) The effective percentage of ownership is more than 50% but the Company does not hold control over relevant business while it exercises significant influence by participating in the Investment Decision Committee. For this reason, the entity is classified as an associate. (*13) The effective percentage of ownership is less than 20% but the Company has joint control over the entity as decisions on the major activities require the unanimous consent of the parties that collectively control the entity (*14) The percentage of ownership decreased since the Company did not participate in the capital increase of Green Biomass Co., Ltd. during the period. (*15) The effective percentage of ownership is more than 50% but the Company does not hold control over the entity according to the shareholders’ agreement. For this reason, the entity is classified as an associate.
The fair value of associates	Investees 2016 2017 In millions of won <Associates> Korea Electric Power Industrial Development Co., Ltd. ￦ 45,474 38,667 Korea Gas Corporation(*) 915,705 804,195 YTN Co., Ltd. 22,320 18,855 SPC Power Corporation 70,253 72,616 PT. Bayan Resources TBK 359,200 558,267 (*) The carrying amount of Korea Gas Corporation (“KOGAS”) is ￦1,618,868 million as of December 31, 2017 and management has determined that there is objective evidence of impairment. As a result of the impairment test, the Company has not recognized any impairment loss as the value in use is greater than the carrying amount. The recoverable amount of KOGAS based on its value in use is calculated by considering the long-term natural gas supply and demand programs of future cash flows approved by Ministry of Trade, Industry & Energy and the discount rate of 4.94%.
Changes in investments in associates and joint ventures	Changes in investments in associates and joint ventures for the years ended December 31, 2016 and 2017 are as follows: 2016 Investees Beginning Acquisition Disposal Dividends Share of Other Others Ending In millions of won <Associates> Daegu Green Power Co., Ltd. ￦ 80,267 3,347 (34,422 ) — (1,814 ) 148 (47,526 ) — Korea Gas Corporation 2,102,813 — — (3,213 ) (146,308 ) (14,551 ) (4,864 ) 1,933,877 Korea Electric Power Industrial Development Co., Ltd. 18,994 — — (1,598 ) 4,491 — (1,412 ) 20,475 YTN Co., Ltd. 38,365 — — — (227 ) 32 (14 ) 38,156 Cheongna Energy Co., Ltd. 19,490 — — — (7,117 ) — — 12,373 Gangwon Wind Power Co., Ltd. 12,890 — — (1,136 ) 1,270 45 — 13,069 Hyundai Green Power Co., Ltd. 113,664 — — (8,888 ) 11,222 — — 115,998 Korea Power Exchange 208,735 — — — 15,847 — (1,344 ) 223,238 AMEC Partners Korea Ltd. 230 — — — (5 ) — — 225 Hyundai Energy Co., Ltd. 6,990 — — — (21,163 ) — 15,204 1,031 Ecollite Co., Ltd. — — — — — — — — Taebaek Wind Power Co., Ltd. 4,956 — — — (206 ) — — 4,750 Taeback Guinemi Wind Power Co., Ltd. 2,587 570 — — (26 ) — — 3,131 Pyeongchang Wind Power Co., Ltd. 3,402 — — — (19 ) — — 3,383 Daeryun Power Co., Ltd. 36,156 — — — (6,282 ) (1 ) — 29,873 JinanJangsu Wind Power Co., Ltd. 77 — (64 ) — (13 ) — — — Changjuk Wind Power Co., Ltd. 6,143 — — (190 ) 977 — — 6,930 KNH Solar Co., Ltd. 1,924 — — — 144 5 — 2,073 SPC Power Corporation 58,033 — — (7,151 ) 6,416 (477 ) (3 ) 56,818 Gemeng International Energy Co., Ltd. 728,396 — — (16,476 ) 26,714 (58,493 ) (76 ) 680,065 PT. Cirebon Electric Power 60,574 — — (1,242 ) 31,511 2,568 3,247 96,658 KNOC Nigerian East Oil Co., Ltd. — — — — (1,346 ) (398 ) 1,744 — KNOC Nigerian West Oil Co., Ltd. — — — — (973 ) (356 ) 1,329 — Dolphin Property Limited 61 — — (35 ) — (69 ) 43 — PT Wampu Electric Power 18,963 — — — 3,493 (3 ) 735 23,188 PT. Bayan Resources TBK(*2) 525,066 — — — (23,257 ) 208 (99,350 ) 402,667 S-Power 130,908 — — — (7,006 ) — 10 123,912 Pioneer Gas Power Limited 51,187 — — — (698 ) 251 — 50,740 Eurasia Energy Holdings — — — — — — — — Xe-Pian Xe-Namnoy 31,863 16,402 — — 1,576 1,703 — 51,544 Busan Solar Co., Ltd. 925 — (887 ) — (38 ) — — — Hadong Mineral Fiber Co., Ltd. — — — — — — — — Green Biomass Co., Ltd. — — — — (138 ) — 185 47 PT. Mutiara Jawa — — — — — — — — Samcheok Eco Materials Co., Ltd. — — — — — — — — Noeul Green Energy Co., Ltd. 295 1,340 — — (418 ) — — 1,217 Naepo Green Energy Co., Ltd. 26,746 — — — (1,308 ) — — 25,438 Goseong Green Energy Co., Ltd. 2,670 — — — 71 — (78 ) 2,663 Gangneung Eco Power Co., Ltd. 2,688 — — — 56 — (98 ) 2,646 Shin Pyeongtaek Power Co., Ltd. — — — — — — — — Heang Bok Do Si Photovoltaic Power Co., Ltd. 189 — — — (10 ) — 2 181 DS POWER Co., Ltd. 10,960 — — — (3,738 ) — (32 ) 7,190 Dongducheon Dream Power Co., Ltd. 55,667 — — — (8,757 ) — (34 ) 46,876 KS Solar Co., Ltd. 618 — — — (14 ) — — 604 Yeongwol Energy Station Co., 1,290 — — — 85 25 (1,400 ) — Jinbhuvish Power Generation Pvt. Ltd.(*3) ￦ 8,350 — — — (49 ) (198 ) (8,103 ) — SE Green Energy Co., Ltd. 3,575 — — — (50 ) — — 3,525 Daegu Photovoltaic Co., Ltd. 1,886 — — (411 ) 225 — — 1,700 Jeongam Wind Power Co., Ltd. 702 3,900 — — (602 ) — — 4,000 Korea Power Engineering Service Co., Ltd. 1,805 — — — 1,005 — — 2,810 Busan Green Energy Co., Ltd. 14,512 — — — (709 ) — — 13,803 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 904 — — — (904 ) — — — Korea Electric Vehicle Charging Service 1,446 — — — (343 ) — — 1,103 Ulleungdo Natural Energy Co., Ltd. 7,417 — — — (516 ) — (7 ) 6,894 Korea Nuclear Partners Co., Ltd. 289 — — — (41 ) — — 248 Tamra Offshore Wind Power Co., Ltd. — 8,910 — — (1,895 ) — — 7,015 Korea Electric Power Corporation Fund — 51,500 — — (644 ) — — 50,856 Energy Infra Asset Management Co., Ltd. — 297 — — (38 ) — — 259 Daegu clean Energy Co., Ltd. — 140 — — — — — 140 YaksuESS Co., Ltd — 210 — — (14 ) — — 196 Nepal Water & Energy Development Company Private Limited — — — — — — 18,667 18,667 4,405,668 86,616 (35,373 ) (40,340 ) (131,583 ) (69,561 ) (123,175 ) 4,092,252 <Joint ventures> KEPCO-Uhde Inc.(*4) 8,549 — — — (159 ) — (8,089 ) 301 Eco Biomass Energy Sdn. Bhd. — — — — — — — — Datang Chaoyang Renewable Power Co., Ltd. 27,640 — — — 1,417 (818 ) — 28,239 Shuweihat Asia Power Investment B.V. 20,474 — (14,154 ) (2,957 ) 6,131 (9,494 ) — — Shuweihat Asia Operation & Maintenance Company 486 — — (931 ) 941 (46 ) — 450 Waterbury Lake Uranium L.P. 20,299 — — — — 1,138 (123 ) 21,314 ASM-BG 20,203 — — — 1,508 (223 ) — 21,488 RES Technology AD 13,789 — — — (68 ) (139 ) — 13,582 KV Holdings, Inc. 2,010 — — (302 ) 429 (39 ) — 2,098 KEPCO SPC Power Corporation 208,524 — — (5,955 ) 48,132 (5,308 ) (26 ) 245,367 Canada Korea Uranium Limited Partnership — — — — — — — — Gansu Datang Yumen Wind Power Co., Ltd. 16,107 — — — (2,836 ) (450 ) — 12,821 Datang Chifeng Renewable Power Co., Ltd. 171,224 — — (7,384 ) 7,455 (4,760 ) — 166,535 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 10,580 — — (440 ) 1,002 (299 ) — 10,843 Rabigh Electricity Company 59,368 — — — 18,961 19,473 — 97,802 Rabigh Operation & Maintenance Company Limited 3,586 — — (1,934 ) 2,253 229 293 4,427 Jamaica Public Service Company Limited 241,918 — — — — 7,535 — 249,453 KW Nuclear Components Co., Ltd. 4,985 — — (2,191 ) 4,344 — (5 ) 7,133 Busan Shinho Solar Power Co., Ltd. 3,678 — — (185 ) 321 — — 3,814 GS Donghae Electric Power Co., Ltd. 200,379 — — — 5,575 — (6 ) 205,948 Global Trade Of Power System Co., Ltd. ￦ 426 — — — 51 — — 477 Expressway Solar-light Power Generation Co., Ltd. 2,100 — — — 243 — — 2,343 KODE NOVUS I LLC — — — — — — — — KODE NOVUS II LLC — 258 — — (260 ) — 2 — Daejung Offshore Wind Power Co., Ltd. 3,352 — — — (337 ) — — 3,015 Amman Asia Electric Power Company 137,668 — — (12,684 ) 17,811 11,062 — 153,857 KAPES, Inc. 4,501 — — — 311 — (54 ) 4,758 Dangjin Eco Power Co., Ltd. 48,281 5,100 — — (696 ) (26 ) 594 53,253 Honam Wind Power Co., Ltd. 3,926 — — (104 ) 629 — — 4,451 Nepal Water & Energy Development Company Private Limited 17,765 — — — 359 543 (18,667 ) — Chun-cheon Energy Co., Ltd. 31,976 19,832 — — (1,121 ) (95 ) — 50,592 Yeonggwangbaeksu Wind Power Co., Ltd. 2,668 — — — 16 — 5 2,689 Nghi Son 2 Power Ltd. 269 716 — — (740 ) (16 ) — 229 Kelar S.A — — — — — — — — PT. Tanjung Power Indonesia 617 — — — 1,337 — (8 ) 1,946 Incheon New Power Co., Ltd. 514 — — — 41 8 — 563 Seokmun Energy Co., Ltd. — — — — (197 ) 793 (205 ) 391 Daehan Wind Power PSC — 285 — — (261 ) (8 ) — 16 Barakah One Company — 118 — — — — (2 ) 116 Nawah Energy Company — 296 — — — — (6 ) 290 MOMENTUM — 1 — — 65 — 1 67 Daegu Green Power Co., Ltd. — — — — — — 47,528 47,528 1,287,862 26,606 (14,154 ) (35,067 ) 112,657 19,060 21,232 1,418,196 ￦ 5,693,530 113,222 (49,527 ) (75,407 ) (18,926 ) (50,501 ) (101,943 ) 5,510,448 (*1) ‘Others’ include ￦1,400 million of assets held-for-sale (*2) It was determined that there is objective evidence of impairment due to prolonged operating losses. As a result, the Company recognized an impairment loss of ￦99,338 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2016. (*3) Due to discontinuation of operations during the year ended December 31, 2016, the Company recognized an impairment loss of ￦8,103 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2016. (*4) It was determined that there is objective evidence of impairment due to prolonged operating losses. As a result, the Company recognized an impairment loss of ￦8,099 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2016. 2017 Investees Beginning Acquisition Disposal Dividends Share of Other Others Ending In millions of won <Associates> Korea Gas Corporation ￦ 1,933,877 — — — (242,232 ) (72,648 ) (129 ) 1,618,868 Korea Electric Power Industrial Development Co., Ltd. 20,475 — — (2,061 ) 3,428 102 (106 ) 21,838 YTN Co., Ltd. 38,156 — — (135 ) 1,095 929 561 40,606 Cheongna Energy Co., Ltd. 12,373 — — — (4,036 ) — — 8,337 Gangwon Wind Power Co., Ltd. 13,069 — — (852 ) 1,638 — — 13,855 Hyundai Green Power Co., Ltd. 115,998 — — (8,889 ) 7,697 — — 114,806 Korea Power Exchange 223,238 — — — 8,831 — 5,562 237,631 AMEC Partners Korea Ltd. 225 — — — (10 ) — — 215 Hyundai Energy Co., Ltd. 1,031 — — — (3,498 ) — 2,467 — Ecollite Co., Ltd. — — — — — — — — Taebaek Wind Power Co., Ltd. 4,750 — — — 569 — — 5,319 Taeback Guinemi Wind Power Co., Ltd. 3,131 — — — (42 ) — — 3,089 Pyeongchang Wind Power Co., Ltd. 3,383 — — — 753 — — 4,136 Daeryun Power Co., Ltd. 29,873 — — — (4,762 ) — 2 25,113 Changjuk Wind Power Co., Ltd. 6,930 — — (111 ) 696 — — 7,515 KNH Solar Co., Ltd. 2,073 — — — 145 — — 2,218 SPC Power Corporation 56,818 — — (5,562 ) 4,310 (3,276 ) (7 ) 52,283 Gemeng International Energy Co., Ltd. 680,065 — — (13,365 ) 6,953 (23,680 ) — 649,973 PT. Cirebon Electric Power 96,658 — — (550 ) 10,685 2,232 (11,615 ) 97,410 KNOC Nigerian East Oil Co., Ltd. — — — — (1,914 ) 1,536 378 — KNOC Nigerian West Oil Co., Ltd. — — — — (1,712 ) 1,407 305 — PT Wampu Electric Power 23,188 — — — 9,336 — (3,121 ) 29,403 PT. Bayan Resources TBK 402,667 — — — 34,122 14,982 60 451,831 S-Power 123,912 — — — (6,982 ) — 15 116,945 Pioneer Gas Power Limited 50,740 — — — (11,119 ) (1,238 ) 276 38,659 Eurasia Energy Holdings — — — — — — — — Xe-Pian Xe-Namnoy 51,544 22,362 — — (4,264 ) (7,863 ) — 61,779 Hadong Mineral Fiber Co., Ltd. — — — — (31 ) — 31 — Green Biomass Co., Ltd. 47 — — — (112 ) — 273 208 PT. Mutiara Jawa — — — — — — — — Samcheok Eco Materials Co., Ltd. — — — — — — — — Noeul Green Energy Co., Ltd. 1,217 — — — 850 — — 2,067 Naepo Green Energy Co., 25,438 — — — (1,400 ) — (3,440 ) 20,598 Goseong Green Energy Co., Ltd. 2,663 — — — (66 ) — — 2,597 Gangneung Eco Power Co., Ltd. 2,646 — — — (63 ) — — 2,583 Shin Pyeongtaek Power Co., Ltd. — 43,880 — — (10,998 ) (3,617 ) 5,638 34,903 Heang Bok Do Si Photovoltaic Power Co., Ltd. 181 — — — 6 — — 187 DS POWER Co., Ltd.(*4) 7,190 — — — (1,321 ) — (5,869 ) — Dongducheon Dream Power Co., Ltd.(*1,3) 46,876 — — — (10,980 ) — 17,337 53,233 KS Solar Co., Ltd. 604 — (613 ) — — 9 — — Jinbhuvish Power Generation Pvt. Ltd. — — — — — — — — SE Green Energy Co., Ltd. 3,525 — — — (49 ) — — 3,476 Daegu Photovoltaic Co., Ltd. 1,700 — — (349 ) 367 — — 1,718 Jeongam Wind Power Co., Ltd. 4,000 — — — (237 ) — — 3,763 Korea Power Engineering Service Co., Ltd. 2,810 — — (191 ) 1,030 — 10 3,659 Busan Green Energy Co., Ltd. 13,803 — (9,320 ) — 2,884 — (4 ) 7,363 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) ￦ — — — — — — — — Korea Electric Vehicle Charging Service 1,103 1,008 — — (362 ) — — 1,749 Ulleungdo Natural Energy Co., Ltd. 6,894 — — — (524 ) — — 6,370 Korea Nuclear Partners Co., Ltd. 248 — — — 135 — — 383 Tamra Offshore Wind Power Co., Ltd. 7,015 — — — 1,545 — — 8,560 Korea Electric Power Corporation Fund 50,856 — — — (2,171 ) (711 ) — 47,974 Energy Infra Asset Management Co., Ltd. 259 — — — 217 — — 476 Daegu clean Energy Co., Ltd. 140 — — — (129 ) — — 11 YaksuESS Co., Ltd 196 — — — (2 ) — — 194 Nepal Water & Energy Development Company Private Limited 18,667 15,009 — — (677 ) (2,501 ) — 30,498 Gwangyang Green Energy Co., Ltd. — 2,000 — — (228 ) — — 1,772 PND solar., Ltd — 1,250 — — — — — 1,250 4,092,252 85,509 (9,933 ) (32,065 ) (212,629 ) (94,337 ) 8,624 3,837,421 <Joint ventures> KEPCO-Uhde Inc. 301 — — — (43 ) — — 258 Eco Biomass Energy Sdn. Bhd. — — — — — — — — Datang Chaoyang Renewable Power Co., Ltd. 28,239 — — (839 ) 840 (978 ) — 27,262 Shuweihat Asia Power Investment B.V. — — — (1,707 ) 4,275 12,457 650 15,675 Shuweihat Asia Operation & Maintenance Company 450 — — (770 ) 1,055 (172 ) 100 663 Waterbury Lake Uranium L.P. 21,314 — — — (23 ) (949 ) (561 ) 19,781 ASM-BG 21,488 — — (946 ) (150 ) 810 — 21,202 RES Technology AD 13,582 — — — 1,053 (260 ) — 14,375 KV Holdings, Inc. 2,098 — — — 61 (241 ) — 1,918 KEPCO SPC Power Corporation 245,367 — — (37,443 ) 42,359 (33,230 ) 41 217,094 Canada Korea Uranium Limited partnership — — — — — — — — Gansu Datang Yumen Wind Power Co., Ltd. 12,821 — — — (1,299 ) (682 ) — 10,840 Datang Chifeng Renewable Power Co., Ltd. 166,535 — — — 14,079 (9,559 ) — 171,055 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 10,843 — — — 837 (620 ) — 11,060 Rabigh Electricity Company 97,802 — — (18,112 ) 35,769 (15,227 ) (876 ) 99,356 Rabigh Operation & Maintenance Company Limited 4,427 — — (2,130 ) 2,236 (546 ) — 3,987 Jamaica Public Service Company Limited 249,453 — — — — (28,300 ) — 221,153 KW Nuclear Components Co., Ltd. 7,133 — — (208 ) (222 ) — — 6,703 Busan Shinho Solar Power Co., Ltd. 3,814 — — (63 ) 595 — — 4,346 GS Donghae Electric Power Co., Ltd. 205,948 — — — 14,714 — 65 220,727 Global Trade Of Power System Co., Ltd. 477 — — — 100 — — 577 Expressway Solar-light Power Generation Co., Ltd. 2,343 — — — 120 — — 2,463 KODE NOVUS I LLC ￦ — — — — — — — — KODE NOVUS II LLC — — — — — — — — Daejung Offshore Wind Power Co., Ltd. 3,015 200 — — (246 ) — — 2,969 Amman Asia Electric Power Company 153,857 — — (12,213 ) 19,957 (15,925 ) — 145,676 KAPES, Inc. 4,758 — — — 2,752 — (34 ) 7,476 Dangjin Eco Power Co., Ltd. 53,253 5,440 — — (752 ) (3 ) (10 ) 57,928 Honam Wind Power Co., Ltd. 4,451 — — (487 ) 338 — — 4,302 Chun-cheon Energy Co., Ltd. 50,592 — — — (2,474 ) — — 48,118 Yeonggwangbaeksu Wind Power Co., Ltd. 2,689 — — — 45 — — 2,734 Nghi Son 2 Power Ltd. 229 993 — — (1,039 ) — — 183 Kelar S.A — 73,040 — — (633 ) (5,175 ) 1 67,233 PT. Tanjung Power Indonesia 1,946 — — — 2,112 (2,281 ) (1 ) 1,776 Incheon New Power Co., Ltd. 563 — — — 56 — — 619 Seokmun Energy Co., Ltd. 391 14,790 — — (1,219 ) (176 ) — 13,786 Daehan Wind Power PSC 16 — — — (40 ) 22 2 — Barakah One Company 116 — — — 570 (60 ) — 626 Nawah Energy Company 290 — — — (5 ) (27 ) — 258 MOMENTUM 67 — — — 321 3 — 391 Daegu Green Power Co., Ltd. 47,528 — — — (5,133 ) — (4 ) 42,391 Yeonggwang Wind Power Co., Ltd. — 15,375 — — (25 ) (56 ) — 15,294 Chester Solar IV SpA — 1,700 — — — — — 1,700 Chester Solar V SpA — 525 — — — — — 525 Diego de Almagro Solar SpA — 2,091 — — — — — 2,091 South Jamaica Power Company Limited — 7,090 — — — — (386 ) 6,704 1,418,196 121,244 — (74,918 ) 130,941 (101,175 ) (1,013 ) 1,493,275 ￦ 5,510,448 206,753 (9,933 ) (106,983 ) (81,688 ) (195,512 ) 7,611 5,330,696 (*1) It was determined that there is objective evidence of impairment due to prolonged operating losses. As a result, the Company recognized an impairment loss of ￦23,798 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2017. (*2) It was determined that there is objective evidence of impairment due to prolonged operating losses. As a result, the Company recognized an impairment loss of ￦3,440 million in impairment loss on investments in associates and joint ventures for the year ended December 31, 2017. (*3) ‘Others’ include ￦41,170 million of assets held-for-sale (*4) ‘Others’ include ￦4,438 million of assets held-for-sale available-for-sale
Summary of financial information of associates and joint ventures	2016 Investees Total assets Total liabilities Sales Profit (loss) for the period In millions of won <Associates> Korea Gas Corporation ￦ 39,927,836 30,541,350 21,108,116 (673,558 ) Korea Electric Power Industrial Development Co., Ltd. 144,346 73,742 304,067 17,187 YTN Co., Ltd. 304,536 126,324 130,690 2,051 Cheongna Energy Co., Ltd. 469,843 447,216 46,484 (16,127 ) Gangwon Wind Power Co., Ltd. 102,550 15,753 22,774 8,133 Hyundai Green Power Co., Ltd. 1,151,975 751,981 469,547 38,743 Korea Power Exchange 255,533 32,295 101,222 15,087 AMEC Partners Korea Ltd. 1,216 32 103 (25 ) Hyundai Energy Co., Ltd. 505,979 499,205 61,813 (45,800 ) Ecollite Co., Ltd. 2,157 336 — (105 ) Taebaek Wind Power Co., Ltd. 43,162 24,162 5,741 (2,796 ) Taeback Guinemi Wind Power Co., Ltd. 12,523 1 — (106 ) Pyeongchang Wind Power Co., Ltd. 75,440 61,909 3,997 (45 ) Daeryun Power Co., Ltd. 793,283 644,930 249,558 (32,291 ) Changjuk Wind Power Co., Ltd. 37,878 15,162 5,782 1,739 KNH Solar Co., Ltd. 25,878 18,199 4,006 638 SPC Power Corporation 191,562 42,042 73,674 42,617 Gemeng International Energy Co., Ltd. 5,822,879 3,821,905 1,233,972 66,370 PT. Cirebon Electric Power 988,975 637,491 265,813 114,653 KNOC Nigerian East Oil Co., Ltd. 272,964 358,211 — (7,051 ) KNOC Nigerian West Oil Co., Ltd. 165,396 243,713 — (6,562 ) PT Wampu Electric Power 222,004 171,595 19,260 7,550 PT. Bayan Resources TBK 945,436 845,963 593,441 402 S-Power 886,841 629,992 453,606 (14,885 ) Pioneer Gas Power Limited 345,791 276,978 14,353 396 Eurasia Energy Holdings 618 1,103 — — Xe-Pian Xe-Namnoy 772,699 543,472 — 6,458 Hadong Mineral Fiber Co., Ltd. — 20 — — Green Biomass Co., Ltd. 9,336 9,001 2,892 (972 ) PT. Mutiara Jawa 28,104 34,671 7,175 (1,361 ) Samcheok Eco Materials Co., Ltd. 24,143 254 — (1,945 ) Noeul Green Energy Co., Ltd. 115,062 110,866 203 (1,155 ) Naepo Green Energy Co., Ltd. 104,029 2,276 4,912 (5,230 ) Goseong Green Energy Co., Ltd. 356,546 110,753 — (5,489 ) Gangneung Eco Power Co., Ltd. 176,805 6,503 — (3,494 ) Shin Pyeongtaek Power Co., Ltd. 54,174 60,518 — (3,291 ) Heang Bok Do Si Photovoltaic Power Co., Ltd. 2,937 2,297 427 (47 ) DS POWER Co., Ltd. 726,699 618,793 276,324 (10,031 ) Dongducheon Dream Power Co., Ltd. 1,670,945 1,427,773 946,379 (27,936 ) KS Solar Co., Ltd. 27,213 24,035 4,152 (79 ) Jinbhuvish Power Generation Pvt. Ltd. 70,273 14,513 — (950 ) SE Green Energy Co., Ltd. 7,381 — — (103 ) Daegu Photovoltaic Co., Ltd. 18,909 13,047 3,317 739 Jeongam Wind Power Co., Ltd. ￦ 13,199 3,199 — (1,496 ) Korea Power Engineering Service Co., Ltd. 13,401 3,713 27,394 3,463 Busan Green Energy Co., Ltd. 147,843 100,247 — (2,444 ) Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 11,340 12,037 — (5,489 ) Korea Electric Vehicle Charging Service 10,545 6,604 5,177 (1,225 ) Ulleungdo Natural Energy Co., Ltd. 24,836 1,738 — (1,730 ) Korea Nuclear Partners Co., Ltd. 1,363 507 372 (140 ) Tamra Offshore Wind Power Co., Ltd. 127,880 101,900 983 (6,307 ) Korea Electric Power Corporation Fund 51,970 128 3 (647 ) Energy Infra Asset Management Co., Ltd. 2,779 160 32 (381 ) Daegu clean Energy Co., Ltd. 500 — — — YaksuESS Co., Ltd 6,474 5,801 — (48 ) Nepal Water & Energy Development Company Private Limited 43,788 10,477 — (703 ) <Joint ventures> KEPCO-Uhde Inc. 624 33 — (16,855 ) Eco Biomass Energy Sdn. Bhd. — — — — Datang Chaoyang Renewable Power Co., Ltd. 142,684 72,086 18,628 3,462 Shuweihat Asia Power Investment B.V. 282 4 — 12,380 Shuweihat Asia Operation & Maintenance Company 1,016 13 2,388 1,723 Waterbury Lake Uranium L.P. 56,181 47 — — ASM-BG 79,898 36,921 12,604 3,105 RES Technology AD 68,553 41,389 7,798 (139 ) KV Holdings, Inc. 5,245 1 — 1,072 KEPCO SPC Power Corporation 448,069 121,783 165,046 63,689 Canada Korea Uranium Limited Partnership 285 144 — (59 ) Gansu Datang Yumen Wind Power Co., Ltd. 89,517 57,464 4,263 (6,815 ) Datang Chifeng Renewable Power Co., Ltd. 813,804 397,344 99,795 19,042 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 62,600 35,493 8,742 2,505 Rabigh Electricity Company 2,691,654 2,258,772 278,431 37,791 Rabigh Operation & Maintenance Company Limited 25,032 13,965 25,607 4,870 Jamaica Public Service Company Limited 1,291,008 659,296 827,298 25,324 KW Nuclear Components Co., Ltd. 26,417 11,990 26,481 9,452 Busan Shinho Solar Power Co., Ltd. 47,789 32,533 6,770 1,247 GS Donghae Electric Power Co., Ltd. 1,952,297 1,346,568 19,851 16,396 Global Trade Of Power System Co., Ltd. 1,661 18 2,667 205 Expressway Solar-light Power Generation Co., Ltd. 20,790 12,710 3,395 960 KODE NOVUS I LLC 14,286 104,252 2,362 (50,151 ) KODE NOVUS II LLC 3,236 50,267 810 (22,582 ) Daejung Offshore Wind Power Co., Ltd. 6,076 34 — (675 ) Amman Asia Electric Power Company 881,164 624,590 13,631 29,684 KAPES, Inc. 145,576 136,247 31,852 456 Dangjin Eco Power Co., Ltd. 149,926 1,001 — (2,023 ) Honam Wind Power Co., Ltd. ￦ 41,614 26,375 6,776 2,171 Chun-cheon Energy Co., Ltd. 548,306 379,113 — (3,684 ) Yeonggwangbaeksu Wind Power Co., Ltd. 99,773 81,881 11,208 (26 ) Nghi Son 2 Power Ltd. 757 302 — (1,481 ) Kelar S.A 617,803 712,124 — (4,109 ) PT. Tanjung Power Indonesia 203,051 197,491 122,583 3,821 Incheon New Power Co., Ltd. 7,902 5,961 2,985 168 Seokmun Energy Co., Ltd. 235,905 234,556 — (543 ) Daehan Wind Power PSC 750 714 — (523 ) Barakah One Company 17,117,338 17,116,680 — — Nawah Energy Company 1,645 — — — MOMENTUM 2,749 2,547 2,886 194 Daegu Green Power Co., Ltd. 636,438 547,017 265,621 (3,981 ) 2017 Investees Total assets Total liabilities Sales Profit (loss) for the period In millions of won <Associates> Korea Gas Corporation ￦ 37,139,439 28,999,025 22,172,305 (1,205,110 ) Korea Electric Power Industrial Development Co., Ltd. 155,033 79,730 334,547 16,126 YTN Co., Ltd. 298,122 108,554 131,080 3,638 Cheongna Energy Co., Ltd. 461,958 448,535 56,533 (9,203 ) Gangwon Wind Power Co., Ltd. 94,281 2,243 25,963 11,121 Hyundai Green Power Co., Ltd. 1,150,729 754,846 477,373 26,543 Korea Power Exchange 263,499 25,868 105,107 8,831 AMEC Partners Korea Ltd. 1,135 4 1 (53 ) Hyundai Energy Co., Ltd. 474,939 511,486 92,992 (43,317 ) Ecollite Co., Ltd. 2,052 352 — (121 ) Taebaek Wind Power Co., Ltd. 39,227 17,953 7,056 2,312 Taeback Guinemi Wind Power Co., Ltd. 12,369 12 — (140 ) Pyeongchang Wind Power Co., Ltd. 77,152 60,606 11,907 3,038 Daeryun Power Co., Ltd. 779,258 655,377 156,508 (23,978 ) Changjuk Wind Power Co., Ltd. 35,794 10,745 6,981 2,317 KNH Solar Co., Ltd. 24,432 16,215 3,947 628 SPC Power Corporation 137,586 — 68,149 37,395 Gemeng International Energy Co., Ltd. 6,496,294 4,584,608 1,334,833 21,769 PT. Cirebon Electric Power 903,429 549,212 280,452 38,448 KNOC Nigerian East Oil Co., Ltd. 241,808 329,639 — (10,754 ) KNOC Nigerian West Oil Co., Ltd. 147,185 227,588 — (9,768 ) PT Wampu Electric Power 212,095 148,177 779 8,114 PT. Bayan Resources TBK 908,106 556,881 811,515 243,621 S-Power 859,633 617,224 489,042 (14,470 ) Pioneer Gas Power Limited 339,271 296,898 8,215 (27,796 ) Eurasia Energy Holdings 548 978 — — Xe-Pian Xe-Namnoy 858,789 607,462 — (16,677 ) Hadong Mineral Fiber Co., Ltd. 203 231 — (260 ) Green Biomass Co., Ltd. 6,379 4,018 2,337 (956 ) PT. Mutiara Jawa ￦ 27,098 29,670 13,574 3,455 Samcheok Eco Materials Co., Ltd. 23,729 270 15 (541 ) Noeul Green Energy Co., Ltd. 127,980 120,852 43,099 2,932 Naepo Green Energy Co., Ltd. 121,375 71,945 5,696 (5,603 ) Goseong Green Energy Co., Ltd. 1,081,238 841,330 — (5,811 ) Gangneung Eco Power Co., Ltd. 186,765 20,344 — (3,407 ) Shin Pyeongtaek Power Co., Ltd. 175,870 90,662 — (4,585 ) Heang Bok Do Si Photovoltaic Power Co., Ltd. 2,782 2,120 451 22 Dongducheon Dream Power Co., Ltd. 1,575,175 1,365,845 813,440 (33,740 ) Jinbhuvish Power Generation Pvt. Ltd. 66,047 13,640 — — SE Green Energy Co., Ltd. 7,278 — — (103 ) Daegu Photovoltaic Co., Ltd. 17,262 11,339 3,714 1,263 Jeongam Wind Power Co., Ltd. 67,427 58,019 — (580 ) Korea Power Engineering Service Co., Ltd. 15,738 3,121 22,283 3,783 Busan Green Energy Co., Ltd. 193,253 167,864 34,280 9,946 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 9,648 16,462 — (6,109 ) Korea Electric Vehicle Charging Service 14,650 8,404 8,399 (1,295 ) Ulleungdo Natural Energy Co., Ltd. 25,842 4,501 — (1,758 ) Korea Nuclear Partners Co., Ltd. 2,033 711 1,345 465 Tamra Offshore Wind Power Co., Ltd. 163,740 132,036 4,392 (191 ) Korea Electric Power Corporation Fund 49,170 265 666 (2,213 ) Energy Infra Asset Management Co., Ltd. 5,240 431 5,807 2,203 Daegu clean Energy Co., Ltd. 252 212 — (460 ) YaksuESS Co., Ltd 7,105 6,437 381 (6 ) Nepal Water & Energy Development Company Private Limited 58,121 11,670 — (968 ) Gwangyang Green Energy Co., Ltd. 20,165 11,393 — (1,139 ) PND solar., Ltd 10,508 6,729 — (406 ) <Joint ventures> KEPCO-Uhde Inc. 515 7 — (86 ) Eco Biomass Energy Sdn. Bhd. — — — — Datang Chaoyang Renewable Power Co., Ltd. 138,463 70,309 17,776 2,149 Shuweihat Asia Power Investment B.V. 32,001 10 — (170 ) Shuweihat Asia Operation & Maintenance Company 1,220 14 2,580 1,918 Waterbury Lake Uranium L.P. 55,563 250 — — ASM-BG 87,110 44,706 12,611 (262 ) RES Technology AD 71,595 42,845 7,793 2,164 KV Holdings, Inc. 4,795 — 671 677 KEPCO SPC Power Corporation 318,911 30,222 186,725 57,364 Gansu Datang Yumen Wind Power Co., Ltd. 81,960 54,859 6,938 (3,253 ) Datang Chifeng Renewable Power Co., Ltd. 762,605 334,843 113,329 35,294 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 60,913 33,264 8,442 2,094 Rabigh Electricity Company 2,364,522 1,936,403 287,105 78,948 Rabigh Operation & Maintenance Company Limited 19,992 10,025 22,668 5,668 Jamaica Public Service Company Limited ￦ 1,276,279 752,617 946,365 24,601 KW Nuclear Components Co., Ltd. 25,693 10,221 6,486 1,493 Busan Shinho Solar Power Co., Ltd. 47,959 30,573 7,984 2,383 GS Donghae Electric Power Co., Ltd. 2,179,465 1,530,266 351,814 43,180 Global Trade Of Power System Co., Ltd. 3,576 1,586 4,079 365 Expressway Solar-light Power Generation Co., Ltd. 19,143 10,651 3,018 643 KODE NOVUS I LLC 755 108,132 14 (8,117 ) KODE NOVUS II LLC 292 47,683 — (6,018 ) Daejung Offshore Wind Power Co., Ltd. 6,193 243 — (493 ) Amman Asia Electric Power Company 759,114 516,174 18,034 33,514 KAPES, Inc. 70,679 56,021 129,962 5,397 Dangjin Eco Power Co., Ltd. 163,197 521 — (2,182 ) Honam Wind Power Co., Ltd. 39,675 24,951 5,961 1,166 Chun-cheon Energy Co., Ltd. 699,652 538,733 164,294 (8,145 ) Yeonggwangbaeksu Wind Power Co., Ltd. 94,810 76,621 11,124 297 Nghi Son 2 Power Ltd. 741 376 — (2,068 ) Kelar S.A 613,293 513,101 90,435 17,590 PT. Tanjung Power Indonesia 374,702 369,627 209,923 6,219 Incheon New Power Co., Ltd. 7,194 5,059 2,972 184 Seokmun Energy Co., Ltd. 247,735 200,197 35,135 (3,939 ) Daehan Wind Power PSC 928 1,752 — (904 ) Barakah One Company 17,574,885 17,571,409 — (1,358 ) Nawah Energy Company 1,459 23 — (11 ) MOMENTUM 5,028 3,854 11,555 939 Daegu Green Power Co., Ltd. 602,809 531,103 256,359 (17,700 ) Yeonggwang Wind Power Co., Ltd. 212,802 176,062 — (62 ) Chester Solar IV SpA 11,660 9,626 331 151 Chester Solar V SpA 2,081 1,569 — (49 ) Diego de Almagro Solar SpA 8,266 5,830 — (103 ) South Jamaica Power Company Limited 153,958 120,436 — (755 )
Financial information of associates and joint ventures in consolidated financial statements	Financial information of associates and joint ventures reconciled to the Company’s investments in consolidated financial statements as of December 31, 2016 and 2017 are as follows: 2016 Investees Net assets Percentage of Share in net assets Investment differential Intercompany transaction Others Book value In millions of won <Associates> Korea Gas Corporation ￦ 9,386,486 21.57 % 2,024,665 — — (90,788 ) 1,933,877 Korea Electric Power Industrial Development Co., Ltd. 70,604 29.00 % 20,475 — — — 20,475 YTN Co., Ltd. 178,212 21.43 % 38,191 — (30 ) (5 ) 38,156 Cheongna Energy Co., Ltd. 22,627 43.90 % 9,933 2,584 (144 ) — 12,373 Gangwon Wind Power Co., Ltd. 86,797 15.00 % 13,020 — — 49 13,069 Hyundai Green Power Co., Ltd. 399,994 29.00 % 115,998 — — — 115,998 Korea Power Exchange 223,238 100.00 % 223,238 — — — 223,238 AMEC Partners Korea Ltd. 1,184 19.00 % 225 — — — 225 Hyundai Energy Co., Ltd. 6,774 46.30 % 3,136 — (1,079 ) (1,026 ) 1,031 Ecollite Co., Ltd. 1,821 36.10 % 657 — — (657 ) — Taebaek Wind Power Co., Ltd. 19,000 25.00 % 4,750 — — — 4,750 Taeback Guinemi Wind Power Co., Ltd. 12,522 25.00 % 3,131 — — — 3,131 Pyeongchang Wind Power Co., Ltd. ￦ 13,531 25.00 % 3,383 — — — 3,383 Daeryun Power Co., Ltd. 148,353 19.45 % 28,855 1,014 — 4 29,873 Changjuk Wind Power Co., Ltd. 22,716 30.00 % 6,815 — — 115 6,930 KNH Solar Co., Ltd. 7,679 27.00 % 2,073 — — — 2,073 SPC Power Corporation 149,520 38.00 % 56,818 — — — 56,818 Gemeng International Energy Co., Ltd. 2,000,974 34.00 % 680,331 — — (266 ) 680,065 PT. Cirebon Electric Power 351,484 27.50 % 96,658 — — — 96,658 KNOC Nigerian East Oil Co., Ltd. (85,247 ) 14.63 % (12,472 ) — — 12,472 — KNOC Nigerian West Oil Co., Ltd. (78,317 ) 14.63 % (11,458 ) — — 11,458 — PT Wampu Electric Power 50,409 46.00 % 23,188 — — — 23,188 PT. Bayan Resources TBK 99,473 20.00 % 19,895 482,109 — (99,337 ) 402,667 S-Power 256,849 49.00 % 125,856 — (1,944 ) — 123,912 Pioneer Gas Power Limited 68,813 40.00 % 27,525 23,147 — 68 50,740 Eurasia Energy Holdings (485 ) 40.00 % (194 ) — — 194 — Xe-Pian Xe-Namnoy 229,227 25.00 % 57,307 (4,802 ) (672 ) (289 ) 51,544 Hadong Mineral Fiber Co., Ltd. (20 ) 25.00 % (5 ) — — 5 — Green Biomass Co., Ltd. 335 14.00 % 47 — — — 47 PT. Mutiara Jawa (6,567 ) 29.00 % (1,904 ) 70 — 1,834 — Samcheok Eco Materials Co., Ltd. 23,889 2.35 % 561 — — (561 ) — Noeul Green Energy Co., Ltd. 4,196 29.00 % 1,217 — — — 1,217 Naepo Green Energy Co., Ltd. 101,753 25.00 % 25,438 — — — 25,438 Goseong Green Energy Co., Ltd. 245,793 1.12 % 2,742 — (79 ) — 2,663 Gangneung Eco Power Co., Ltd. 170,302 1.61 % 2,744 — (98 ) — 2,646 Shin Pyeongtaek Power Co., Ltd. (6,344 ) 40.00 % (2,538 ) — (3,380 ) 5,918 — Heang Bok Do Si Photovoltaic Power Co., Ltd. 640 28.00 % 179 — — 2 181 DS POWER Co., Ltd. 107,906 14.44 % 15,582 — (7,302 ) (1,090 ) 7,190 Dongducheon Dream Power Co., Ltd. 243,172 33.61 % 81,730 — (4,768 ) (30,086 ) 46,876 KS Solar Co., Ltd. 3,178 19.00 % 604 — — — 604 Jinbhuvish Power Generation Pvt. Ltd. 55,760 5.16 % 2,877 — — (2,877 ) — SE Green Energy Co., Ltd. 7,381 47.76 % 3,525 — — — 3,525 Daegu Photovoltaic Co., Ltd. 5,862 29.00 % 1,700 — — — 1,700 Jeongam Wind Power Co., Ltd. 10,000 40.00 % 4,000 — — — 4,000 Korea Power Engineering Service Co., Ltd. 9,688 29.00 % 2,810 — — — 2,810 Busan Green Energy Co., Ltd. 47,596 29.00 % 13,803 — — — 13,803 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) (697 ) 18.87 % (132 ) — — 132 — Korea Electric Vehicle Charging Service 3,941 28.00 % 1,103 — — — 1,103 Ulleungdo Natural Energy Co., Ltd. 23,098 29.85 % 6,895 — — (1 ) 6,894 Korea Nuclear Partners Co., Ltd. 856 29.00 % 248 — — — 248 Tamra Offshore Wind Power Co., Ltd. 25,980 27.00 % 7,015 — — — 7,015 Korea Electric Power Corporation Fund 51,842 98.09 % 50,852 — — 4 50,856 Energy Infra Asset Management Co., Ltd. 2,619 9.90 % 259 — — — 259 Daegu clean Energy Co., Ltd. 500 28.00 % 140 — — — 140 YaksuESS Co., Ltd 673 29.00 % 195 — — 1 196 Nepal Water & Energy Development Company Private Limited 33,311 52.77 % 17,578 972 — 117 18,667 <Joint ventures> KEPCO-Uhde Inc. 591 50.85 % 301 — — — 301 Eco Biomass Energy Sdn. Bhd. — 61.53 % — — — — — Datang Chaoyang Renewable Power Co., Ltd. 70,598 40.00 % 28,239 — — — 28,239 Shuweihat Asia Power Investment B.V. 278 49.00 % 136 — — (136 ) — Shuweihat Asia Operation & Maintenance Company 1,003 55.00 % 552 — — (102 ) 450 Waterbury Lake Uranium L.P. 56,134 36.97 % 20,753 — — 561 21,314 ASM-BG 42,977 50.00 % 21,489 — — (1 ) 21,488 RES Technology AD 27,164 50.00 % 13,582 — — — 13,582 KV Holdings, Inc. 5,244 40.00 % 2,098 — — — 2,098 KEPCO SPC Power Corporation 326,286 75.20 % 245,367 — — — 245,367 Canada Korea Uranium Limited Partnership 141 12.50 % 18 — — (18 ) — Gansu Datang Yumen Wind Power Co., Ltd. ￦ 32,053 40.00 % 12,821 — — — 12,821 Datang Chifeng Renewable Power Co., Ltd. 416,460 40.00 % 166,584 — — (49 ) 166,535 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 27,107 40.00 % 10,843 — — — 10,843 Rabigh Electricity Company 432,882 40.00 % 173,153 — (75,311 ) (40 ) 97,802 Rabigh Operation & Maintenance Company Limited 11,067 40.00 % 4,427 — — — 4,427 Jamaica Public Service Company Limited 631,712 40.00 % 252,685 (80,161 ) — 76,929 249,453 KW Nuclear Components Co., Ltd. 14,427 45.00 % 6,492 90 — 551 7,133 Busan Shinho Solar Power Co., Ltd. 15,256 25.00 % 3,814 — — — 3,814 GS Donghae Electric Power Co., Ltd. 605,729 34.00 % 205,948 — — — 205,948 Global Trade Of Power System Co., Ltd. 1,643 29.00 % 476 — — 1 477 Expressway Solar-light Power Generation Co., Ltd. 8,080 29.00 % 2,343 — — — 2,343 KODE NOVUS I LLC (89,966 ) 50.00 % (44,983 ) 4,732 — 40,251 — KODE NOVUS II LLC (47,031 ) 50.00 % (23,516 ) — — 23,516 — Daejung Offshore Wind Power Co., Ltd. 6,042 49.90 % 3,015 — — — 3,015 Amman Asia Electric Power Company 256,574 60.00 % 153,944 — — (87 ) 153,857 KAPES, Inc. 9,329 51.00 % 4,758 — — — 4,758 Dangjin Eco Power Co., Ltd. 148,925 34.00 % 50,635 2,618 — — 53,253 Honam Wind Power Co., Ltd. 15,239 29.00 % 4,419 32 — — 4,451 Chun-cheon Energy Co., Ltd. 169,193 29.90 % 50,589 3 — — 50,592 Yeonggwangbaeksu Wind Power Co., Ltd. 17,892 15.00 % 2,684 5 — — 2,689 Nghi Son 2 Power Ltd. 455 50.00 % 228 — — 1 229 Kelar S.A (94,321 ) 65.00 % (61,309 ) 2,424 — 58,885 — PT. Tanjung Power Indonesia 5,560 35.00 % 1,946 — — — 1,946 Incheon New Power Co., Ltd. 1,941 29.00 % 563 — — — 563 Seokmun Energy Co., Ltd. 1,349 29.00 % 391 — — — 391 Daehan Wind Power PSC 36 50.00 % 18 — — (2 ) 16 Barakah One Company 658 18.00 % 118 — — (2 ) 116 Nawah Energy Company 1,645 18.00 % 296 — — (6 ) 290 MOMENTUM 202 33.33 % 67 — — — 67 Daegu Green Power Co., Ltd. 89,421 29.00 % 25,932 84 — 21,512 47,528 (*) The percentage of ownership shown above is after considering the treasury stocks and others. 2017 Investees Net assets Percentage of Share in net assets Investment differential Intercompany transaction Others Book value In millions of won <Associates> Korea Gas Corporation ￦ 8,140,414 21.57 % 1,755,887 — — (137,019 ) 1,618,868 Korea Electric Power Industrial Development Co., Ltd. 75,303 29.00 % 21,838 — — — 21,838 YTN Co., Ltd. 189,568 21.43 % 40,624 — (18 ) — 40,606 Cheongna Energy Co., Ltd. 13,423 43.90 % 5,893 2,584 (140 ) — 8,337 Gangwon Wind Power Co., Ltd. 92,038 15.00 % 13,806 — — 49 13,855 Hyundai Green Power Co., Ltd. 395,883 29.00 % 114,806 — — — 114,806 Korea Power Exchange 237,631 100.00 % 237,631 — — — 237,631 AMEC Partners Korea Ltd. 1,131 19.00 % 215 — — — 215 Hyundai Energy Co., Ltd. (36,547 ) 46.30 % (16,921 ) — (1,037 ) 17,958 — Ecollite Co., Ltd. 1,700 36.10 % 614 — — (614 ) — Taebaek Wind Power Co., Ltd. 21,274 25.00 % 5,319 — — — 5,319 Taeback Guinemi Wind Power Co., Ltd. 12,357 25.00 % 3,089 — — — 3,089 Pyeongchang Wind Power Co., Ltd. 16,546 25.00 % 4,136 — — — 4,136 Daeryun Power Co., Ltd. 123,881 19.45 % 24,095 1,014 — 4 25,113 Changjuk Wind Power Co., Ltd. 25,049 30.00 % 7,515 — — — 7,515 KNH Solar Co., Ltd. 8,217 27.00 % 2,218 — — — 2,218 SPC Power Corporation 137,586 38.00 % 52,283 — — — 52,283 Gemeng International Energy Co., Ltd. 1,911,686 34.00 % 649,973 — — — 649,973 PT. Cirebon Electric Power 354,217 27.50 % 97,410 — — — 97,410 KNOC Nigerian East Oil Co., Ltd. ￦ (87,831 ) 14.63 % (12,850 ) — — 12,850 — KNOC Nigerian West Oil Co., Ltd. (80,403 ) 14.63 % (11,763 ) — — 11,763 — PT Wampu Electric Power 63,918 46.00 % 29,403 — — — 29,403 PT. Bayan Resources TBK 351,225 20.00 % 70,245 482,109 — (100,523 ) 451,831 S-Power 242,409 49.00 % 118,780 — (1,835 ) — 116,945 Pioneer Gas Power Limited 42,373 38.50 % 16,314 22,278 — 67 38,659 Eurasia Energy Holdings (430 ) 40.00 % (172 ) — — 172 — Xe-Pian Xe-Namnoy 251,327 25.00 % 62,832 74 (838 ) (289 ) 61,779 Hadong Mineral Fiber Co., Ltd. (28 ) 8.33 % (2 ) — — 2 — Green Biomass Co., Ltd. 2,361 8.80 % 208 — — — 208 PT. Mutiara Jawa (2,572 ) 29.00 % (746 ) — — 746 — Samcheok Eco Materials Co., Ltd. 23,459 2.35 % 551 — — (551 ) — Noeul Green Energy Co., Ltd. 7,128 29.00 % 2,067 — — — 2,067 Naepo Green Energy Co., Ltd. 49,430 41.67 % 20,598 — — — 20,598 Goseong Green Energy Co., Ltd. 239,908 1.12 % 2,676 — (79 ) — 2,597 Gangneung Eco Power Co., Ltd. 166,421 1.61 % 2,681 — (98 ) — 2,583 Shin Pyeongtaek Power Co., Ltd. 85,208 40.00 % 34,083 7,808 (6,988 ) — 34,903 Heang Bok Do Si Photovoltaic Power Co., Ltd. 662 28.00 % 185 — — 2 187 Dongducheon Dream Power Co., Ltd. 209,330 33.61 % 70,356 — (4,409 ) (12,714 ) 53,233 Jinbhuvish Power Generation Pvt. Ltd. 52,407 5.16 % 2,704 — — (2,704 ) — SE Green Energy Co., Ltd. 7,278 47.76 % 3,476 — — — 3,476 Daegu Photovoltaic Co., Ltd. 5,923 29.00 % 1,718 — — — 1,718 Jeongam Wind Power Co., Ltd. 9,408 40.00 % 3,763 — — — 3,763 Korea Power Engineering Service Co., Ltd. 12,617 29.00 % 3,659 — — — 3,659 Busan Green Energy Co., Ltd. 25,389 29.00 % 7,363 — — — 7,363 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) (6,814 ) 18.87 % (1,286 ) — — 1,286 — Korea Electric Vehicle Charging Service 6,246 28.00 % 1,749 — — — 1,749 Ulleungdo Natural Energy Co., Ltd. 21,341 29.85 % 6,370 — — — 6,370 Korea Nuclear Partners Co., Ltd. 1,322 29.00 % 383 — — — 383 Tamra Offshore Wind Power Co., Ltd. 31,704 27.00 % 8,560 — — — 8,560 Korea Electric Power Corporation Fund 48,905 98.09 % 47,971 — — 3 47,974 Energy Infra Asset Management Co., Ltd. 4,809 9.90 % 476 — — — 476 Daegu clean Energy Co., Ltd. 40 28.00 % 11 — — — 11 YaksuESS Co., Ltd 668 29.00 % 193 — — 1 194 Nepal Water & Energy Development Company Private Limited 46,451 62.13 % 28,860 972 — 666 30,498 Gwangyang Green Energy Co., Ltd. 8,772 20.00 % 1,754 18 — — 1,772 PND solar., Ltd 3,779 29.00 % 1,096 154 — — 1,250 <Joint ventures> KEPCO-Uhde Inc. 508 50.85 % 258 — — — 258 Eco Biomass Energy Sdn. Bhd. — 61.53 % — — — — — Datang Chaoyang Renewable Power Co., Ltd. 68,154 40.00 % 27,262 — — — 27,262 Shuweihat Asia Power Investment B.V. 31,991 49.00 % 15,675 — — — 15,675 Shuweihat Asia Operation & Maintenance Company 1,206 55.00 % 663 — — — 663 Waterbury Lake Uranium L.P. 55,313 35.76 % 19,780 — — 1 19,781 ASM-BG 42,404 50.00 % 21,202 — — — 21,202 RES Technology AD 28,750 50.00 % 14,375 — — — 14,375 KV Holdings, Inc. 4,795 40.00 % 1,918 — — — 1,918 KEPCO SPC Power Corporation 288,689 75.20 % 217,094 — — — 217,094 Gansu Datang Yumen Wind Power Co., Ltd. 27,101 40.00 % 10,840 — — — 10,840 Datang Chifeng Renewable Power Co., Ltd. 427,762 40.00 % 171,105 — — (50 ) 171,055 Datang KEPCO Chaoyang Renewable Power Co., Ltd. 27,649 40.00 % 11,060 — — — 11,060 Rabigh Electricity Company 428,119 40.00 % 171,248 — (70,978 ) (914 ) 99,356 Rabigh Operation & Maintenance Company Limited ￦ 9,967 40.00 % 3,987 — — — 3,987 Jamaica Public Service Company Limited 523,662 40.00 % 209,464 (80,161 ) — 91,850 221,153 KW Nuclear Components Co., Ltd. 15,472 45.00 % 6,962 — — (259 ) 6,703 Busan Shinho Solar Power Co., Ltd. 17,386 25.00 % 4,346 — — — 4,346 GS Donghae Electric Power Co., Ltd. 649,199 34.00 % 220,727 — — — 220,727 Global Trade Of Power System Co., Ltd. 1,990 29.00 % 577 — — — 577 Expressway Solar-light Power Generation Co., Ltd. 8,492 29.00 % 2,463 — — — 2,463 KODE NOVUS I LLC (107,377 ) 50.00 % (53,689 ) — — 53,689 — KODE NOVUS II LLC (47,391 ) 50.00 % (23,696 ) — — 23,696 — Daejung Offshore Wind Power Co., Ltd. 5,950 49.90 % 2,969 — — — 2,969 Amman Asia Electric Power Company 242,940 60.00 % 145,764 — — (88 ) 145,676 KAPES, Inc. 14,658 51.00 % 7,476 — — — 7,476 Dangjin Eco Power Co., Ltd. 162,676 34.00 % 55,310 2,618 — — 57,928 Honam Wind Power Co., Ltd. 14,724 29.00 % 4,270 32 — — 4,302 Chun-cheon Energy Co., Ltd. 160,919 29.90 % 48,115 3 — — 48,118 Yeonggwangbaeksu Wind Power Co., Ltd. 18,189 15.00 % 2,728 6 — — 2,734 Nghi Son 2 Power Ltd. 365 50.00 % 183 — — — 183 Kelar S.A 100,192 65.00 % 65,125 2,424 — (316 ) 67,233 PT. Tanjung Power Indonesia 5,075 35.00 % 1,776 — — — 1,776 Incheon New Power Co., Ltd. 2,135 29.00 % 619 — — — 619 Seokmun Energy Co., Ltd. 47,538 29.00 % 13,786 — — — 13,786 Daehan Wind Power PSC (824 ) 50.00 % (412 ) — — 412 — Barakah One Company 3,476 18.00 % 626 — — — 626 Nawah Energy Company 1,436 18.00 % 258 — — — 258 MOMENTUM 1,174 33.33 % 391 — — — 391 Daegu Green Power Co., Ltd. 71,706 29.00 % 20,795 — 84 21,512 42,391 Yeonggwang Wind Power Co., Ltd. 36,740 41.00 % 15,063 231 — — 15,294 Chester Solar IV SpA 2,034 81.82 % 1,664 — — 36 1,700 Chester Solar V SpA 512 81.82 % 419 — — 106 525 Diego de Almagro Solar SpA 2,436 81.82 % 1,993 — — 98 2,091 South Jamaica Power Company Limited 33,522 20.00 % 6,704 — — — 6,704 (*) The percentage of ownership shown above is after considering the treasury stocks and others.
Unrecognized equity interest in investments in associates and joint ventures	2016 2017 Unrecognized Accumulated unrecognized Unrecognized Accumulated unrecognized In millions of won Shin Pyeongtaek Power Co., Ltd. ￦ 1,211 2,537 (2,537 ) — Seokmun Energy Co., Ltd. (205 ) — — — Kelar S.A 43,920 61,309 (61,309 ) — Hadong Mineral Fiber Co., Ltd. — 5 (3 ) 2 PT. Mutiara Jawa 554 1,905 (1,159 ) 746 Eurasia Energy Holdings 6 194 (22 ) 172 KODE NOVUS I LLC 22,194 44,983 8,706 53,689 KODE NOVUS II LLC 12,340 23,515 181 23,696 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 132 132 1,154 1,286 Daehan Wind Power PSC — — 412 412
Shareholders’ agreements on investments in associates and joint ventures	(i) Gemeng International Energy Co., Ltd. Gemeng International Energy Co., Ltd., issued put options on 8% of its shares to its financial investors, KEPCO Woori Sprott PEF (NPS Co-Pa (ii) Hyundai Energy Co., Ltd. The Company had placed guarantees for a fixed return on the investment to NH Power II Co., Ltd. and National Agricultural Cooperative Federation (“NACF”) and had obtained the rights to acquire the investment securities in return preferentially. In addition, NH Power II Co., Ltd. and NACF have a right, which can be exercised for 30 days starting from 2 months to 1 month prior to 17 years after the termination date of the contract to sell their shares to the Company. (iii) Taebaek Wind Power Co., Ltd. In case non-controlling (iv) Pyeongchang Wind Power Co., Ltd. In case non-controlling (v) Jeongam Wind Power Co., Ltd. In case non-controlling (vi) Daejung Offshore Wind Power Co., Ltd. In case Samsung Heavy Industries Co., Ltd., a co-participant (vii) Samcheok Eco Materials Co., Ltd. The Company has the rights to purchase the stocks should preferred stockholders elect to sell their stocks on the expected sell date (3 years from preferred stock payment date) and is required to guarantee the promised yield when preferred stockholders sell their stocks. (viii) Hyundai Green Power Co., Ltd. As of December 31, 2017, Hyundai Green Power Co., Ltd., an associate of the Company, which engages in the byproduct gas power generating business, entered into a project financing agreement with a limit of ￦919.2 billion with Korea Development Bank and others. At a certain period in the future, the Company has an appraisal right against the financial investors (Korea Development Bank and others) and also has an obligation to sell its shares when claimed by the financial investors. At a certain period in the future, the Company has an appraisal right against Hyundai Steel Company and a third party designated by Hyundai Steel Company (collectively, “Hyundai Steel Company”), the operating investor of Hyundai Green Power Co., Ltd., according to the conditions of the agreement and also has an obligation to sell its shares when claimed by Hyundai Steel Company.
Significant restrictions on its abilities to associates or joint ventures	Company Nature and extent of any significant restrictions Daeryun Power Co., Ltd. Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Changjuk Wind Power Co., Ltd. Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Taebaek Wind Power Co., Ltd. Financial institutions can reject or defer an approval with regard to the request for fund executions on subordinated loans of shareholders in order to pay senior loans based on the loan agreement. Pyeongchang Wind Power Co., Ltd. Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Daegu Green Power Co., Ltd. Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Shares cannot be wholly or partially transferred without prior written consent of financial institutions is obtained. KNH Solar Co., Ltd. Principal and interest, dividends to shareholders cannot be paid without written consent of financial institutions.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment as of December 31, 2016 and 2017 are as follows: 2016 Acquisition cost Government grants Accumulated depreciation Accumulated losses(*) Book value In millions of won Land ￦ 12,969,741 (3,204 ) — — 12,966,537 Buildings 17,722,326 (61,188 ) (5,936,849 ) (853 ) 11,723,436 Structures 63,291,437 (197,641 ) (19,959,839 ) (1,183 ) 43,132,774 Machinery 67,769,168 (111,064 ) (24,344,832 ) (2,391 ) 43,310,881 Ships 4,175 — (3,625 ) — 550 Vehicles 247,751 (107 ) (176,781 ) — 70,863 Equipment 1,270,660 (732 ) (894,265 ) — 375,663 Tools 921,115 (430 ) (742,083 ) — 178,602 Construction-in- 27,334,368 (135,807 ) — (38,108 ) 27,160,453 Finance lease assets 2,390,779 — (1,984,426 ) — 406,353 Asset retirement costs 7,129,771 — (3,064,359 ) — 4,065,412 Others 10,361,294 — (8,009,762 ) — 2,351,532 ￦ 211,412,585 (510,173 ) (65,116,821 ) (42,535 ) 145,743,056 (*) The Company separately recognizes impairment loss on each asset, reflecting various factors such as physical impairment and others during the replacement. 2017 Acquisition cost Government grants Accumulated depreciation Accumulated losses(*) Book value In millions of won Land ￦ 13,318,542 (21,968 ) — — 13,296,574 Buildings 18,777,678 (63,539 ) (6,722,376 ) (1,776 ) 11,989,987 Structures 66,184,484 (196,414 ) (22,071,667 ) (8,039 ) 43,908,364 Machinery 75,826,292 (183,188 ) (28,904,982 ) (45,512 ) 46,692,610 Ships 4,175 — (3,772 ) — 403 Vehicles 276,425 (6,322 ) (195,260 ) (127 ) 74,716 Equipment 1,440,870 (761 ) (1,020,192 ) (6 ) 419,911 Tools 1,010,537 (1,027 ) (809,842 ) (32 ) 199,636 Construction-in-progress 25,610,649 (49,084 ) — (38,108 ) 25,523,457 Finance lease assets 2,390,680 (27 ) (2,093,001 ) — 297,652 Asset retirement costs 9,395,821 — (3,356,337 ) — 6,039,484 Others 11,247,021 — (8,807,401 ) — 2,439,620 ￦ 225,483,174 (522,330 ) (73,984,830 ) (93,600 ) 150,882,414 (*) The Company separately recognizes impairment loss on each asset, reflecting various factors such as physical impairment and others during the replacement.
Changes in property, plant and equipment	2016 Beginning Acquisition Disposal Depreciation Impairment Others Ending balance In millions of won Land ￦ 12,396,460 13,973 (52,569 ) — — 611,877 12,969,741 (Government grants) (3,147 ) — 14 — — (71 ) (3,204 ) Buildings 9,676,432 — (9,020 ) (676,866 ) — 2,794,078 11,784,624 (Government grants) (63,932 ) — 731 5,299 — (3,286 ) (61,188 ) Structures 40,258,162 455 (524,310 ) (2,233,333 ) — 5,829,441 43,330,415 (Government grants) (193,119 ) — 2,597 9,491 — (16,610 ) (197,641 ) Machinery 36,864,749 193,017 (243,757 ) (4,353,596 ) — 10,961,532 43,421,945 (Government grants) (108,935 ) (33 ) 1,210 12,272 — (15,578 ) (111,064 ) Ships 786 — — (281 ) — 45 550 Vehicles 60,472 2,493 (34 ) (27,615 ) — 35,654 70,970 (Government grants) (29 ) (58 ) — 25 — (45 ) (107 ) Equipment 310,571 67,134 (323 ) (128,084 ) — 127,097 376,395 (Government grants) (1,026 ) — — 452 — (158 ) (732 ) Tools 160,630 27,856 (327 ) (69,842 ) — 60,715 179,032 (Government grants) (691 ) — — 295 — (34 ) (430 ) Construction-in-progress 35,267,026 11,752,352 (94,443 ) — — (19,628,675 ) 27,296,260 (Government grants) (139,898 ) (28,434 ) — — — 32,525 (135,807 ) Finance lease assets 511,509 34 (31 ) (96,254 ) — (8,905 ) 406,353 Asset retirement costs 4,106,087 — — (509,310 ) — 468,635 4,065,412 Others 2,259,244 — (9 ) (813,248 ) — 905,545 2,351,532 ￦ 141,361,351 12,028,789 (920,271 ) (8,880,595 ) — 2,153,782 145,743,056 2017 Beginning Acquisition Disposal Depreciation Impairment( ) Others Ending balance In millions of won Land ￦ 12,969,741 32,773 (8,961 ) — — 324,989 13,318,542 (Government grants) (3,204 ) — 5 — — (18,769 ) (21,968 ) Buildings 11,784,624 40,592 (19,715 ) (794,804 ) (923 ) 1,043,752 12,053,526 (Government grants) (61,188 ) (900 ) 28 5,996 — (7,475 ) (63,539 ) Structures 43,330,415 428 (519,366 ) (2,421,168 ) (6,856 ) 3,721,325 44,104,778 (Government grants) (197,641 ) — 1,905 10,011 — (10,689 ) (196,414 ) Machinery 43,421,945 421,892 (242,428 ) (4,821,595 ) (43,121 ) 8,139,105 46,875,798 (Government grants) (111,064 ) (10,834 ) 489 17,390 — (79,169 ) (183,188 ) Ships 550 — — (147 ) — — 403 Vehicles 70,970 3,447 (174 ) (34,236 ) (127 ) 41,158 81,038 (Government grants) (107 ) (107 ) 14 1,070 — (7,192 ) (6,322 ) Equipment 376,395 53,529 (413 ) (158,614 ) (6 ) 149,781 420,672 (Government grants) (732 ) (43 ) — 454 — (440 ) (761 ) Tools 179,032 30,990 (166 ) (74,909 ) (32 ) 65,748 200,663 (Government grants) (430 ) — — 354 — (951 ) (1,027 ) Construction-in-progress 27,296,260 11,996,508 (6,487 ) — — (13,713,740 ) 25,572,541 (Government grants) (135,807 ) (42,728 ) — — — 129,451 (49,084 ) Finance lease assets 406,353 — (29,696 ) (107,390 ) — 28,412 297,679 (Government grants) — — — 1 — (28 ) (27 ) Asset retirement costs 4,065,412 — — (518,565 ) — 2,492,637 6,039,484 Others 2,351,532 10,411 (28 ) (762,711 ) — 840,416 2,439,620 ￦ 145,743,056 12,535,958 (824,993 ) (9,658,863 ) (51,065 ) 3,138,321 150,882,414 (*) Korea Midland Power Co., Ltd. and Korea Western Power Co., Ltd., 100% owned subsidiaries, have determined that there are impairment indicators for the shutdowns of certain power generation units and fire, and performed an impairment test over the individual assets. As a result, the Company recognized the amount of the carrying amount in excess of its recoverable amount as impairment loss in the consolidated statements of comprehensive income.

Investment Properties (Tables)

Investment Properties (Tables)	12 Months Ended
	Dec. 31, 2017
Investment Properties [Abstract]
Investment Properties	2016 Acquisition cost Government grants Accumulated Book value In millions of won Land ￦ 336,421 — — 336,421 Buildings 29,168 (64 ) (11,845 ) 17,259 ￦ 365,589 (64 ) (11,845 ) 353,680 2017 Acquisition cost Government grants Accumulated Book value In millions of won Land ￦ 264,205 — — 264,205 Buildings 36,165 (83 ) (15,573 ) 20,509 ￦ 300,370 (83 ) (15,573 ) 284,714
Changes in investment properties	2016 Beginning balance Depreciation Others Ending balance In millions of won Land ￦ 253,960 — 82,461 336,421 Buildings 15,963 (679 ) 2,039 17,323 (Government grants) (13 ) 1 (52 ) (64 ) ￦ 269,910 (678 ) 84,448 353,680 2017 Beginning balance Depreciation Others Ending balance In millions of won Land ￦ 336,421 — (72,216 ) 264,205 Buildings 17,323 (1,178 ) 4,447 20,592 (Government grants) (64 ) 2 (21 ) (83 ) ￦ 353,680 (1,176 ) (67,790 ) 284,714
Income and expenses related to investment properties	2016 2017 In millions of won Rental income ￦ 9,460 9,581 Operating and maintenance expenses related to rental income (678 ) (1,172 ) ￦ 8,782 8,409
Fair value of investment properties	2016 2017 Book value Fair value Book value Fair value In millions of won Land ￦ 336,421 374,042 264,205 309,241 Buildings 17,259 20,708 20,509 23,319 ￦ 353,680 394,750 284,714 332,560 The fair values of the investment properties as of the reporting date were determined in consideration of the fluctuation on the publicly announced individual land price after the IFRS transition date (January 1, 2010).

Construction Services Contrac78

Construction Services Contracts (Tables)	12 Months Ended
	Dec. 31, 2017
Construction Services Contracts [Abstract]
Changes in total contract amount in which revenue is not yet recognized	Changes in total contract amount in which revenue is not yet recognized for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 Beginning balance Increase (decrease)(*) Recognized as revenue Ending In millions of won Nuclear power plant construction in UAE and others ￦ 17,081,074 (1,011,031 ) (3,761,204 ) 12,308,839 (*) For the year ended December 31, 2015, the increased balance of contracts from new orders and other is ￦412,617 million and the decreased balance of contracts due to changes in scope of construction work is ￦1,423,648 million. 2016 Beginning balance Increase (decrease)(*) Recognized as revenue Ending In millions of won Nuclear power plant construction in UAE and others ￦ 12,308,839 (1,045,094 ) (4,026,857 ) 7,236,888 (*) For the year ended December 31, 2016, the increased balance of contracts from new orders and other is ￦718,118 million and the decreased balance of contracts due to changes in scope of construction work is ￦1,763,212 million. 2017 Beginning balance Increase (decrease)(*) Recognized as revenue Ending In millions of won Nuclear power plant construction in UAE and others ￦ 7,236,888 151,891 (3,212,184 ) 4,176,595 (*) For the year ended December 31, 2017, the increased balance of contracts from new orders and other is ￦438,142 million and the decreased balance of contracts due to changes in scope of construction work is ￦286,251 million.
Accumulated earned revenue, expense and others	2016 Accumulated earned revenue Accumulated expense Accumulated profit Unearned advance receipts In millions of won Nuclear power plant construction in UAE and others ￦ 15,314,737 14,396,890 917,847 — 2017 Accumulated earned revenue Accumulated expense Accumulated profit Unearned advance receipts In millions of won Nuclear power plant construction in UAE and others ￦ 18,236,992 16,937,772 1,299,220 —
Gross amount of assets and liabilities for contract	2016 2017 Assets(*1) Liabilities(*2) Assets(*1) Liabilities(*2) In millions of won Nuclear power plant construction in UAE and others ￦ 44,930 651,985 55,755 542,921 (*1) Included in trade and other receivables, net, in the consolidated statements of financial position. (*2) Included in non-financial

Intangible Assets other than 79

Intangible Assets other than Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Intangible Assets other than Goodwill [Abstract]
Intangible Assets other than Goodwill	2016 Acquisition Government Accumulated Accumulated Book value In millions of won Software ￦ 458,382 (595 ) (365,161 ) — 92,626 Licenses and franchises 3,398 — (3,398 ) — — Copyrights, patents rights and other industrial rights 35,756 — (15,675 ) — 20,081 Mining rights 549,371 — (10,511 ) — 538,860 Development expenditures 785,966 (5,152 ) (723,561 ) — 57,253 Intangible assets under Development 119,474 (11,090 ) — (3,941 ) 104,443 Usage rights of donated assets and other 426,346 (21 ) (342,244 ) — 84,081 Leasehold rights 23,350 — (18,718 ) — 4,632 Greenhouse gas emissions rights 6,283 — — — 6,283 Others 173,213 — (88,527 ) (12,124 ) 72,562 ￦ 2,581,539 (16,858 ) (1,567,795 ) (16,065 ) 980,821 2017 Acquisition Government Accumulated Accumulated Book value In millions of won Software ￦ 534,191 (486 ) (408,300 ) — 125,405 Licenses and franchises 3,398 — (3,398 ) — — Copyrights, patents rights and other industrial rights 43,857 — (19,876 ) — 23,981 Mining rights 553,876 — (14,243 ) — 539,633 Development expenditures 836,996 (3,702 ) (752,478 ) — 80,816 Intangible assets under development 143,851 (10,540 ) — (3,941 ) 129,370 Usage rights of donated assets and other 459,682 (11 ) (358,024 ) — 101,647 Leasehold rights 24,306 — (19,262 ) — 5,044 Others 297,289 — (103,995 ) (12,069 ) 181,225 ￦ 2,897,446 (14,739 ) (1,679,576 ) (16,010 ) 1,187,121
Changes in intangible assets	Changes in intangible assets for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Acquisition Disposal Amortization Impairment Others Ending In millions of won Software ￦ 57,886 18,267 — (32,378 ) — 49,446 93,221 (Government grants) (699 ) — — 249 — (145 ) (595 ) Copyrights, patents rights and other industrial rights 21,875 85 (39 ) (2,697 ) — 857 20,081 Mining rights 499,537 26,311 — (899 ) — 13,911 538,860 Development expenditures 51,807 212 — (21,993 ) — 32,379 62,405 (Government grants) (6,835 ) — — 2,771 — (1,088 ) (5,152 ) Intangible assets under development 94,886 66,588 — — (3,945 ) (41,996 ) 115,533 (Government grants) (10,483 ) (1,597 ) — — — 990 (11,090 ) Usage rights of donated assets and other 48,591 — — (15,513 ) — 51,024 84,102 (Government grants) (32 ) — — 11 — — (21 ) Leasehold rights 745 — — (351 ) — 4,238 4,632 Greenhouse gas emissions rights 805 6,283 — — — (805 ) 6,283 Others 97,750 8,273 (550 ) (8,916 ) 3 (23,998 ) 72,562 (Government grants) (1 ) — — 1 — — — ￦ 855,832 124,422 (589 ) (79,715 ) (3,942 ) 84,813 980,821 2017 Beginning Acquisition Disposal Amortization Impairment Others Ending In millions of won Software ￦ 93,221 12,700 (5 ) (44,809 ) — 64,784 125,891 (Government grants) (595 ) (17 ) — 255 — (129 ) (486 ) Copyrights, patents rights and other industrial rights 20,081 30 (7 ) (3,350 ) — 7,227 23,981 Mining rights 538,860 26,751 (272 ) (4,640 ) — (21,066 ) 539,633 Development expenditures 62,405 494 — (25,924 ) — 47,543 84,518 (Government grants) (5,152 ) — — 2,811 — (1,361 ) (3,702 ) Intangible assets under development 115,533 56,527 — — (20 ) (32,130 ) 139,910 (Government grants) (11,090 ) — — — — 550 (10,540 ) Usage rights of donated assets and other 84,102 — — (14,462 ) — 32,018 101,658 (Government grants) (21 ) — — 10 — — (11 ) Leasehold rights 4,632 — — (545 ) — 957 5,044 Greenhouse gas emissions rights 6,283 — — — — (6,283 ) — Others 72,562 47,402 (377 ) (23,018 ) 54 84,602 181,225 (Government grants) — — — — — — — ￦ 980,821 143,887 (661 ) (113,672 ) 34 176,712 1,187,121
Significant specific intangible assets	2016 Type Description Currency Amount Remaining useful years In millions of won and thousands of Australian dollars Software ERP system and others KRW 506 11 months ~ 1 year and 11 months SCADA O/S (POWERON RELIANCE) KRW 4,206 3 years and 1 month Copyrights, patents rights and other industrial rights Smart technology verification and standard design project conducting right KRW 5,750 5 years and 9 months Mining rights Mining right of Bylong mine AUD 401,225 — (*) Development expenditures Development of maintenance system for utility plant KRW 518 11 months Intangible assets under development Contributions to ARP NRC DC KRW 41,190 — Usage rights of donated assets and others Sejong Haengbogdosi sharing charge KRW 44,502 9 years and 11 months Dangjin power plant load facility usage right KRW 26,759 4 years and 3 months Others Sillim electricity supply facility usage right KRW 2,196 4 years and 11 months (*) Mining rights are amortized using the units-of-production 2017 Type Description Currency Amount Remaining useful lives millions of won and thousands of Australian dollars Software ERP system and others KRW 1,135 3 years and 2 months ~ 3 years and 4 months AMI GATEWAY S/W KRW 3,528 3 years and 2 months Copyrights, patents rights and other industrial rights Smart technology verification and standard design project conducting right KRW 11,724 4 years and 9 months Mining rights Mining right of Bylong mine AUD 401,225 — (*) Development expenditures Electricity sales information system KRW 29,391 4 years 3 months Intangible assets under development Contributions to ARP NRC DC KRW 46,458 — Usage rights of donated assets and others Sejong Haengbogdosi sharing charge KRW 40,460 8 years and 11 months Dangjin power plant load facility usage right KRW 20,463 3 years 3 months Others Occupancy and use of public waters KRW 103,269 18 years 11 months (*) Mining rights are amortized using the units-of-production
Recognized research and development expenses	705,504 million and 721,437 million, respectively.

Trading liabilities (Tables)

Trading liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Trade and Other Payables [Abstract]
Trade and Other Payables	Trade and other payables as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Trade payables ￦ 2,610,373 — 2,936,990 — Other trade payables 1,498,582 3,033,780 1,649,933 2,825,039 Accrued expenses 1,152,933 2,161 1,087,844 1,951 Leasehold deposits received 1,426 1,008 1,562 1,308 Other deposits received 197,711 93,751 186,817 102,896 Finance lease liabilities 121,176 420,003 131,792 286,468 Dividends payable 3,204 — 4,448 — Others (*) 6 7,472 135 5,818 ￦ 5,585,411 3,558,175 5,999,521 3,223,480 (*) Details of others as of December 31, 2016 and 2017 are as follows: 2016 2017 Current Non-current Current Non-current In millions of won Advance received from local governments ￦ — 7,472 — 5,818 Others 6 — 135 — ￦ 6 7,472 135 5,818

Borrowings and Debt Securities

Borrowings and Debt Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Borrowings and Debt Securities [Abstract]
Borrowings and Debt Securities	2016 2017 In millions of won Current liabilities Short-term borrowings ￦ 805,523 1,038,328 Current portion of long-term borrowings 310,977 128,543 Current portion of debt securities 7,825,310 7,961,182 Less : Current portion of discount on long-term borrowings (979 ) (886 ) Less : Current portion of discount on debt securities (1,753 ) (3,882 ) 8,939,078 9,123,285 Non-current Long-term borrowings 1,799,750 2,455,737 Debt securities 43,012,960 43,270,825 Less : Discount on long-term borrowings (25,859 ) (21,113 ) Less : Discount on debt securities (86,880 ) (81,424 ) Add: Premium on debt securities 156 82 44,700,127 45,624,107 ￦ 53,639,205 54,747,392
Repayment schedule of borrowings and debt securities	2016 Type Borrowings Debt Securities In millions of won Less than 1 year ￦ 1,116,500 7,825,310 1~ 5 years 295,162 24,462,410 Over 5 years 1,504,588 18,550,550 ￦ 2,916,250 50,838,270 2017 Type Borrowings Debt Securities In millions of won Less than 1 year ￦ 1,166,871 7,961,182 1~ 5 years 1,117,222 25,047,075 Over 5 years 1,338,515 18,223,750 ￦ 3,622,608 51,232,007
Short-term borrowings	2016 Type Creditor Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local short-term borrowings Woori Investment Bank and others 1.54~2.51 2017.01.25~ 2017.09.13 — ￦ 436,800 Foreign short-term borrowings SCNT and others 1.58~6.50 2017.03.30~ 2017.12.03 USD 35,086 42,401 Foreign short-term borrowings Export-import Bank of Korea 3M 2017.05.17~ 2017.12.18 AUD 311,174 271,360 Local bank overdraft Nonghyup Bank 2.45 2017.01.05 — 37,000 Local bank overdraft Woori Bank Standard overdraft 2017.02.25 — 17,962 ￦ 805,523 2017 Type Creditor Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local short-term borrowings KTB Investment and securities and others 1.57~2.47 2018.01.12~ 2018.09.19 — ￦ 686,561 Foreign short-term borrowings SCNT and others 4.60~6.50 2018.12.03 USD 8,955 9,594 Foreign short-term Export-import Bank of Korea 3M 2018.12.18 AUD 327,259 273,314 Local bank overdraft Nonghyup Bank 3.04 2018.01.02 51,300 Local bank overdraft Woori Bank Standard overdraft 2018.02.27 — 17,559 ￦ 1,038,328
Long-term borrowings	2016 Type Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local long-term borrowings Korea Development Bank Others 0.50 2018~2044 — ￦ 5,663 Facility 2.45~4.60 2023~2028 — 61,835 Facility 1yr KoFC bond rate +0.31 2018 — 125,000 Operating funds 2.75 2018 — 12,000 KEB Hana Bank Commercial Paper 3M CD+0.14 2017 — 100,000 Facility 4.60 2028 — 16,851 Facility 3yr KTB rate -1.25 2017~2028 — 9,655 IBK PF Refinancing CD+1.25 2030 — 22,500 Export-Import Bank of Korea Project loans 1.50 2026 — 30,935 Korea Resources Corporation Development of power resources 3yr KTB rate -2.25 2022~2025 — 14,039 Facility 3yr KTB rate -2.25 2017~2024 — 3,842 Project loans — 2022~2025 — 3,733 Others KTB rate -2.25 2024~2025 — 12,131 Shinhan Bank and others Collateral borrowing 2.22 2017 — 30,000 Facility CB rate+1.10 2028 — 25,276 Operating funds 2.70~2.86 2017~2018 — 25,000 Others 4.10 2035 — 55,000 Others 3yr KTB rate+1.10 2035 — 55,000 Kookmin Bank Facility MOR+0.62~0.79 2017~2023 — 45,000 Others Facility 1.75~4.60 2026~2029 — 146,472 Facility CB rate+1.10~1.20 2022~2028 — 34,951 PF Refinancing 4.10 2030 — 62,500 Others 8.00 2036 — 102,347 Others — 2028 — 7,250 1,006,980 Foreign long-term borrowings Korea National Oil Corporation Project loans — 2021~2023 USD 8,744 10,567 Export-Import Bank of Korea and others Direct loan and others 3M Libor+2.75~ 2027 JOD 178,892 305,332 Commercial loan and others 3M Libor+1.50~ 2030~2033 USD 299,859 362,379 PF Loan 6M Libor+2.50~ 2032 USD 119,647 144,594 SCNT and others Shareholder’s loan 6.50~8.00 2023 USD 40,618 49,086 Shareholder’s loan 8.00 2031 JOD 7,128 12,166 PT PJB Shareholder’s loan 12.75 2019 IDR 16,705,505 1,500 Samsung Life Insurance and others Syndicated Loan 3.10 2032 JPY 1,758,000 18,227 Woori Bank and others Syndicated Loan JPY 6M Libor+2.10 2032 JPY 1,172,000 12,151 SMBC and others Equity Bridge Loan 1M Libor+0.90 2019 USD 37,978 45,897 IFC and others Others 6M Libor+5.00 2031 PKR 11,706,160 134,972 Others Others — 2019 USD 5,691 6,876 1,103,747 2,110,727 Less : Discount of long-term borrowings (26,838 ) Less : Current portion of long-term borrowings (310,977 ) Add : Current portion of discount on long-term borrowings 979 ￦ 1,773,891 2017 Type Interest rate (%) Maturity Foreign currency Local currency In millions of won and thousands of foreign currencies Local long-term borrowings Korea Development Bank Others 0.50 2018~2044 — ￦ 4,909 Facility 2.45~4.60 2023~2028 — 68,883 Facility 1yr KoFC bond rate 2018 — 25,000 Operating funds 2.59~3.04 2018~2020 — 47,000 Operating funds 1yr KoFC bond rate +0.95 2020 — 14,000 KEB Hana Bank Commercial Paper 3M CD+0.24~0.32 2021~2022 — 400,000 Facility 4.60 2028 — 15,038 Facility 3yr KTB rate-1.25 2018~2028 — 8,947 IBK PF Refinancing CD+1.25 2030 — 22,500 Export-Import Bank of Korea Project loans 1.50 2026 — 25,042 Operating funds 2.21 2020 — 35,000 Korea Energy Development of power resources 3yr KTB rate-2.25 2023~2025 — 6,765 Facility 3yr KTB rate-2.25 2018~2024 — 3,121 Project loans — 2022~2025 — 3,733 Others KTB rate -2.25 2024~2028 — 18,455 Shinhan Bank Collateral borrowing 2.32 2019 — 30,000 Facility CB rate +1.10 2028 — 22,557 Operating funds 2.70 2018 — 15,000 Others 4.10 2035 — 105,000 Others Standard overdraft 2035 — 105,000 Kookmin Bank Facility 3.16 2020 — 10,000 Facility MOR+0.79 2023 — 35,000 Others Facility 1.75~4.60 2026~2029 — 148,423 Facility CB rate +1.10~1.20 2022~2028 — 46,278 PF Refinancing 4.10 2030 — 62,500 Others 4.50~8.00 2022~2039 — 102,346 1,380,497 Foreign long-term borrowings Korea Energy Project loans — 2021~2023 USD 8,744 9,368 Export-Import Bank of Korea and others Direct loan and others 1M Libor+1.80~3.20 2036 USD 64,913 69,548 Direct loan and others 3M Libor+2.75~3.70 2027 JOD 168,663 254,514 Commercial loan and others 3M Libor+1.50~2.50 2030~2033 USD 289,026 309,662 PF Loan 6M Libor+1.70~2.50 2032 USD 123,253 132,054 SCNT and others Shareholder’s loan 6.50~8.00 2023 USD 41,718 44,697 Shareholder’s loan 8.00 2031 JOD 5,136 7,750 PT PJB Shareholder’s loan 12.75 2019 IDR 10,932,568 864 Samsung Life Insurance and others Syndicated Loan 3.10 2032 JPY 5,325,000 50,540 Woori Bank and others Syndicated Loan JPY 6M Libor+2.00 2032 JPY 3,435,000 32,602 SMBC and others Equity Bridge Loan 1M Libor+0.90 2019 USD 70,986 76,054 IFC and others Others 6M Libor+5.00 2031 PKR 16,652,350 161,195 Federal Financing Bank PF loan 2.39 2031 USD 48,366 51,819 Others Others — 2019 USD 2,907 3,116 1,203,783 2,584,280 Less : Discount of long-term borrowings (21,999 ) Less : Current portion of long-term borrowings (128,543 ) Add : Current portion of discount on long-term borrowings 886 ￦ 2,434,624 (*) As of July 1, 2017, loan business for energy-related projects has been integrated into Korea Energy Agency in accordance with the Korean government’s restructuring of the public institutions.
Local debt securities	Issue date Maturity Interest rate (%) 2016 2017 In millions of won Electricity Bonds 2009.12.03~ 2017.12.14 2018.01.07~ 2037.09.18 1.62~5.45 ￦ 19,860,000 20,700,000 Electricity Bonds 2013.06.25 2018.06.25 3M CD+0.31 310,000 150,000 Corporate Bonds(*1) 2009.05.04~ 2017.11.10 2018.01.18~ 2047.10.17 1.36~5.84 19,552,708 21,122,708 39,722,708 41,972,708 Less : Discount on local debt securities (34,667 ) (37,816 ) Less : Current portion of local debt securities (5,650,010 ) (5,200,000 ) Add : Current portion of discount on local debt securities 728 923 ￦ 34,038,759 36,735,815 (*1) Corporate Bonds of HeeMang Sunlight Power Co., Ltd (￦2,697 million) can be redeemed every March 31 after five years from its issue date, March 31, 2016.
Foreign debt securities	2016 Type Issue date Maturity Interest rate (%) Foreign currency Local currency In millions of won and thousands of foreign currencies FY-96 1996.04.01~ 1996.12.06 2026.12.06~ 2096.04.01 6.00~8.37 USD 249,068 ￦ 300,999 FY-97 1997.01.31~ 1997.08.04 2027.02.01~ 2027.08.01 6.75~7.00 USD 314,717 380,335 FY-04 2004.04.23 2034.04.23 5.13 USD 286,920 346,743 FY-08 2008.11.27 2018.11.27 4.19 JPY 20,000,000 207,362 FY-11 2011.07.13~ 2011.07.29 2017.01.30~ 2021.07.13 3.63~4.75 USD 800,000 966,800 FY-12 2012.05.10~ 2012.09.19 2017.05.10~ 2022.09.19 2.50~3.13 USD 1,750,000 2,114,875 FY-13 2013.02.05~ 2013.11.27 2018.02.05~ 2018.11.27 1.88~2.88 USD 1,900,000 2,296,150 FY-13 2013.09.26~ 2013.10.23 2019.03.26~ 2019.04.23 1.50~1.63 CHF 400,000 472,532 FY-13 2013.09.25 2020.09.25 5.75 AUD 325,000 283,416 FY-13 2013.02.20~ 2013.07.25 2018.02.20~ 2018.07.25 3M Libor+0.84~1.50 USD 500,000 604,250 FY-14 2014.02.11~ 2014.12.02 2019.02.11~ 2029.07.30 2.38~3.57 USD 1,500,000 1,812,750 FY-14 2014.01.28~ 2014.07.31 2017.01.28~ 2017.07.31 3M Libor+0.55~1.05 USD 500,000 604,250 FY-15 2015.06.15 2025.06.15 3.25 USD 300,000 362,550 FY-16 2016.01.21 2021.07.21 2.50 USD 300,000 362,550 11,115,562 Less : Discount on foreign debt securities (53,966 ) Add : Premium on foreign debt securities 156 Less : Current portion of foreign debt securities (2,175,300 ) Add : Current portion of discount on foreign debt securities 1,025 ￦ 8,887,477 2017 Type Issue date Maturity Interest rate (%) Foreign currency Local currency In millions of won and thousands of foreign currencies FY-96 1996.04.01~ 1996.12.06 2026.12.01~ 2096.04.01 6.00~8.37 USD 249,070 ￦ 266,854 FY-97 1997.01.31~ 1997.08.04 2027.02.01~ 2027.08.01 6.75~7.00 USD 314,717 337,188 FY-04 2004.04.23 2034.04.23 5.13 USD 286,920 307,406 FY-08 2008.11.27 2018.11.27 4.19 JPY 20,000,000 189,822 FY-11 2011.07.13 2021.07.13 4.75 USD 500,000 535,700 FY-12 2012.09.19 2022.09.19 3 USD 750,000 803,550 FY-13 2013.02.05~ 2013.11.27 2018.02.05~ 2018.11.27 1.88~2.88 USD 1,900,000 2,035,660 FY-13 2013.09.26~ 2013.10.23 2019.03.26~ 2019.04.23 1.50~1.63 CHF 400,000 437,888 FY-13 2013.09.25 2020.09.25 5.75 AUD 325,000 271,427 FY-13 2013.02.20~ 2013.07.25 2018.02.20~ 2018.07.25 3M Libor+0.84~1.50 USD 500,000 535,700 FY-14 2014.02.11~ 2014.12.02 2019.02.11~ 2029.07.30 2.38~3.57 USD 1,500,000 1,607,100 FY-15 2015.06.15 2025.06.15 3.25 USD 300,000 321,420 FY-16 2016.01.21 2021.07.21 2.5 USD 300,000 321,420 FY-17 2017.04.12~ 2017.07.25 2020.04.12~ 2027.07.25 2.38~3.13 USD 1,100,000 1,178,540 FY-17 2017.10.30 2037.10.30 1.7 EUR 40,000 51,170 FY-17 2017.11.16 2037.11.16 2.36 SEK 450,000 58,454 9,259,299 Less : Discount on foreign debt securities (47,490 ) Add : Premium on foreign debt securities 82 Less : Current portion of foreign debt securities (2,761,182 ) Add : Current portion of discount on foreign debt securities 2,959 ￦ 6,453,668
Changes in borrowings and debt securities	Beginning balance Cash flow Effect of exchange rate Others Ending balance In millions of won 53,639,205 2,269,513 (1,169,418) 8,092 54,747,392

Finance Lease Liabilities (Tabl

Finance Lease Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Finance Lease Liabilities [Abstract]
Finance Lease Liabilities	non-current 2016 2017 Minimum lease Present value of Minimum lease Present value of In millions of won Less than 1 year ￦ 175,512 121,176 174,534 131,792 1 ~ 5 years 404,029 306,282 272,994 204,069 More than 5 years 152,247 113,721 108,748 82,399 ￦ 731,788 541,179 556,276 418,260
Current and non-current portion of financial lease liabilities	Current and non-current 2016 2017 In millions of won Current finance lease liabilities ￦ 121,176 131,792 Non-current 420,003 286,468 ￦ 541,179 418,260
Minimum lease payment and contingent rent payment recognized as an expense	2016 2017 In millions of won Minimum lease payment ￦ 177,585 158,859 Contingent rent payment (20,956 ) (21,024 )
Changes in finance lease liabilities	Changes in finance lease liabilities for the year ended December 31, 2017 are as follows: Beginning balance Cash flow Ending balance In millions of won ￦541,179 (122,919) 418,260

Employment Benefits (Tables)

Employment Benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Employment Benefits [Abstract]
Employment Benefits	Employment benefit obligations as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Net defined benefit obligations ￦ 1,678,470 1,476,201 Other long-term employee benefit obligations 7,788 6,868 ￦ 1,686,258 1,483,069
Principal assumptions on actuarial valuation	2016 2017 Discount rate 2.45%~2.64% 2.75%~2.90% Future salary and benefit levels 5.23% 4.88% Weighted average duration 13.34 years 13.40 years
Details of expense relating to defined benefit plans	Details of expense relating to defined benefit plans for the years ended December 31, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Current service cost ￦ 315,811 378,930 392,820 Interest cost 63,808 67,104 79,524 Expected return on plan assets (22,557 ) (23,612 ) (31,307 ) Loss from settlement (641 ) (706 ) (1,055 ) ￦ 356,421 421,716 439,982 Expenses as described above are recognized in those items below in the financial statements. 2015 2016 2017 In millions of won Cost of sales ￦ 262,760 312,391 332,249 Selling and administrative expenses 51,932 61,362 59,111 Others (Construction-in-progress 41,729 47,963 48,622 ￦ 356,421 421,716 439,982
Details of defined benefits	2016 2017 In millions of won Present value of defined benefit obligation from funded plans ￦ 2,867,377 2,951,842 Fair value of plan assets (1,188,907 ) (1,475,641 ) 1,678,470 1,476,201 Present value of defined benefit obligation from unfunded plans — — Net liabilities incurred from defined benefit plans ￦ 1,678,470 1,476,201
Changes in the present value of defined benefits	2016 2017 In millions of won Beginning balance ￦ 2,426,414 2,867,377 Current service cost 378,930 392,820 Interest cost(*) 67,104 79,524 Remeasurement component 120,993 (258,223 ) Loss from settlement (707 ) (1,055 ) Actual payments (125,233 ) (128,707 ) Others (124 ) 106 Ending balance ￦ 2,867,377 2,951,842 (*) Corporate bond (AAA rated) yield at year-end
Changes in the fair value of plan assets	2016 2017 In millions of won Beginning balance ￦ 930,632 1,188,907 Expected return 23,612 31,307 Remeasurement component (5,706 ) (10,435 ) Contributions by the employers 312,125 325,080 Actual payments (71,756 ) (59,218 ) Ending balance ￦ 1,188,907 1,475,641
Details of the fair value of plan assets	Details of the fair value of plan assets as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Equity instruments ￦ 86,054 79,204 Debt instruments 383,654 517,040 Bank deposit 305,670 293,477 Others 413,529 585,920 ￦ 1,188,907 1,475
Remeasurement component recognized in other comprehensive income (loss)	Remeasurement component recognized in other comprehensive income (loss) for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Actuarial gain from changes in financial assumptions ￦ (27,792 ) (300,058 ) Experience adjustments 148,785 41,835 Expected return 5,706 10,435 ￦ 126,699 (247,788 )

Provisions (Tables)

Provisions (Tables)	12 Months Ended
	Dec. 31, 2017
Provisions [Abstract]
Provisions	2016 2017 Current Non-current Current Non-current In millions of won Employment benefits Provisions for employment benefits ￦ 810,607 — 913,787 — Litigation Litigation provisions 79,359 118,878 48,621 24,955 Decommissioning cost Nuclear plants — 10,195,928 — 13,007,228 Spent fuel — 1,374,225 — 1,339,046 Waste 2,566 1,476,936 11,494 1,626,877 PCBs — 191,744 — 180,087 Other recovery provisions — 507 — 6,659 Others Power plant regional support program 152,851 — 153,756 — Transmission regional support program 282,608 — 243,365 — Provisions for tax 106 136 61 — Provisions for financial guarantee 458 29,207 — 23,475 Provisions for RPS 417,404 — 271,624 — Provisions for greenhouse gas emissions obligations 249,644 — 414,252 — Others 4,385 39,590 80,538 16,387 ￦ 1,999,988 13,427,151 2,137,498 16,224,714
Changes in provisions	2016 Beginning Increase in Payment Reversal Others Ending balance In millions of won Employment benefits Provisions for employment benefits ￦ 718,365 1,047,342 (947,982 ) (7,108 ) (10 ) 810,607 Litigation Litigation provisions 167,965 124,931 (294,403 ) (20,736 ) 220,480 198,237 Decommissioning cost Nuclear plants 9,684,286 513,383 (1,741 ) — — 10,195,928 Spent fuel 1,375,185 469,982 (470,942 ) — — 1,374,225 Waste 1,502,140 49,092 (71,998 ) — 268 1,479,502 PCBs 182,400 30,675 (21,331 ) — — 191,744 Other recovery provisions 862 — — (20 ) (335 ) 507 Others Power plant regional support program 129,655 50,252 (41,540 ) — 14,484 152,851 Transmission regional support program 228,785 253,664 (199,841 ) — — 282,608 Provisions for tax 136 125 — — (19 ) 242 Provisions for financial guarantee 4,288 29,741 — (4,298 ) (66 ) 29,665 Provisions for RPS 363,178 420,154 (309,975 ) (55,953 ) — 417,404 Provisions for greenhouse gas emissions obligations 78,829 298,618 (116,336 ) (11,467 ) — 249,644 Others 7,856 37,491 (2,699 ) (9 ) 1,336 43,975 ￦ 14,443,930 3,325,450 (2,478,788 ) (99,591 ) 236,138 15,427,139 2017 Beginning Increase in Payment Reversal Others Ending balance In millions of won Employment benefits Provisions for employment benefits ￦ 810,607 984,896 (880,255 ) (1,461 ) — 913,787 Litigation Litigation provisions 198,237 34,629 (152,461 ) (7,096 ) 267 73,576 Decommissioning cost Nuclear plants 10,195,928 2,818,033 (6,733 ) — — 13,007,228 Spent fuel 1,374,225 307,682 (342,861 ) — — 1,339,046 Waste 1,479,502 222,632 (63,763 ) — — 1,638,371 PCBs 191,744 5,309 (14,266 ) (2,700 ) — 180,087 Other recovery provisions 507 5,939 — — 213 6,659 Others Power plant regional support program 152,851 94,039 (103,889 ) — 10,755 153,756 Transmission regional support program 282,608 143,178 (182,421 ) — — 243,365 Provisions for tax 242 — (25 ) (136 ) (20 ) 61 Provisions for financial guarantee 29,665 3,760 — (9,945 ) (5 ) 23,475 Provisions for RPS 417,404 242,946 (388,726 ) — — 271,624 Provisions for greenhouse gas emissions obligations 249,644 422,666 (256,758 ) (1,300 ) — 414,252 Others(*) 43,975 6,639 (3,348 ) (26,477 ) 76,136 96,925 ￦ 15,427,139 5,292,348 (2,395,506 ) (49,115 ) 87,346 18,362,212 (*) As described in note 50.(1), the Company believes that the possibility of economic outflow is probable on the cost of construction suspension of Shin-Kori Unit 5 and 6 for three months. For this reason, the Company recognized ￦77,261 million of provision as addition to construction-in-progress.

Government Grants (Tables)

Government Grants (Tables)	12 Months Ended
	Dec. 31, 2017
Government grants [Abstract]
Government Grants	Government grants as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Land ￦ (3,204 ) (21,968 ) Buildings (61,188 ) (63,539 ) Structures (197,641 ) (196,414 ) Machinery (111,064 ) (183,188 ) Vehicles (107 ) (6,322 ) Equipment (732 ) (761 ) Tools (430 ) (1,027 ) Construction-in-progress (135,807 ) (49,084 ) Finance lease assets — (27 ) Investment properties (64 ) (83 ) Software (595 ) (486 ) Development expenditures (5,152 ) (3,702 ) Intangible assets under development (11,090 ) (10,540 ) Usage rights of donated assets and other (21 ) (11 ) Other intangible assets other than goodwill — — ￦ (527,095 ) (537,152 )
Changes in government Grants	2016 Beginning Receipt Acquisition Offset the Disposal Others Ending In millions of won Cash ￦ — (32,878 ) — — — 32,878 — Land (3,147 ) — — — 14 (71 ) (3,204 ) Buildings (63,932 ) — — 5,299 731 (3,286 ) (61,188 ) Structures (193,119 ) — — 9,491 2,597 (16,610 ) (197,641 ) Machinery (108,935 ) — — 12,272 1,210 (15,611 ) (111,064 ) Vehicles (29 ) — — 25 — (103 ) (107 ) Equipment (1,026 ) — — 452 — (158 ) (732 ) Tools (691 ) — — 295 — (34 ) (430 ) Construction-in-progress (139,898 ) — 32,525 — — (28,434 ) (135,807 ) Investment properties (13 ) — — 1 — (52 ) (64 ) Software (699 ) — — 249 — (145 ) (595 ) Development expenditures (6,835 ) — — 2,771 — (1,088 ) (5,152 ) Intangible assets under development (10,483 ) — 991 — — (1,598 ) (11,090 ) Usage rights of donated assets and other (32 ) — — 11 — — (21 ) Others (1 ) — — 1 — — — ￦ (528,840 ) (32,878 ) 33,516 30,867 4,552 (34,312 ) (527,095 ) 2017 Beginning Receipt Acquisition Offset the Disposal Others Ending In millions of won Cash ￦ — (55,533 ) — — — 55,533 — Land (3,204 ) — — — 5 (18,769 ) (21,968 ) Buildings (61,188 ) — — 5,996 28 (8,375 ) (63,539 ) Structures (197,641 ) — — 10,011 1,905 (10,689 ) (196,414 ) Machinery (111,064 ) — — 17,390 489 (90,003 ) (183,188 ) Vehicles (107 ) — — 1,070 14 (7,299 ) (6,322 ) Equipment (732 ) — — 454 — (483 ) (761 ) Tools (430 ) — — 354 — (951 ) (1,027 ) Construction-in-progress (135,807 ) — 129,451 — — (42,728 ) (49,084 ) Finance lease assets — — — 1 — (28 ) (27 ) Investment properties (64 ) — — 2 — (21 ) (83 ) Software (595 ) — — 255 — (146 ) (486 ) Development expenditures (5,152 ) — — 2,811 — (1,361 ) (3,702 ) Intangible assets under development (11,090 ) — — — — 550 (10,540 ) Usage rights of donated assets and other (21 ) — — 10 — — (11 ) Others — — — — — — — ￦ (527,095 ) (55,533 ) 129,451 38,354 2,441 (124,770 ) (537,152 )

Deferred Revenues (Tables)

Deferred Revenues (Tables)	12 Months Ended
	Dec. 31, 2017
Deferred Revenues [Abstract]
Deferred Revenues	Deferred revenue related to the Company’s construction contracts for the years ended December 31, 2016 and 2017 are as follows which included in current and non-current non-financial 2016 2017 In millions of won Beginning balance ￦ 7,165,297 7,825,765 Increase during the current year / period 1,087,765 978,389 Recognized as revenue during the current year / period (427,297 ) (478,973 ) Ending balance ￦ 7,825,765 8,325,181

Non-financial Liabilities (Tabl

Non-financial Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Non-financial Liabilities	Non-financial 2016 2017 Current Non-current Current Non-current In millions of won Advance received ￦ 4,498,739 148,404 3,772,713 181,612 Unearned revenue 26,084 41,936 41,593 19,718 Deferred revenue 445,018 7,380,747 476,631 7,848,550 Withholdings 263,263 10,781 164,370 10,529 Others 1,135,106 9,737 1,129,001 12,025 ￦ 6,368,210 7,591,605 5,584,308 8,072,434

Contributed Capital (Tables)

Contributed Capital (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of classes of share capital [Abstract]
Issued Capital	2016 Shares authorized Shares issued Par value per share Owned by Owned by Total In millions of won except share information Common shares 1,200,000,000 641,964,077 ￦ 5,000 1,640,385 1,569,435 3,209,820 (*) Korea Development Bank’s ownership of ￦1,056,176 million is included. 2017 Shares authorized Shares issued Par value per share Owned by Owned by Total In millions of won except share information Common shares 1,200,000,000 641,964,077 ￦ 5,000 1,640,385 1,569,435 3,209,820 (*) Korea Development Bank’s ownership of ￦1,056,176 million is included.
Number of Issued Capital	2016 2017 Number of shares Beginning balance 641,964,077 641,964,077 Ending balance 641,964,077 641,964,077
Share premium	Details of share premium as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Share premium ￦ 843,758 843,758

Retained Earnings and Dividen89

Retained Earnings and Dividends Paid (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Retained Earnings and Dividends Paid [Abstract]
Retained Earnings	2016 2017 In millions of won Legal reserve(*) ￦ 1,604,910 1,604,910 Voluntary reserves 31,847,275 34,833,844 Retained earnings before appropriations 19,721,686 16,931,804 Retained earnings ￦ 53,173,871 53,370,558 (*) The KEPCO Act requires KEPCO to appropriate a legal reserve equal to at least 20 percent of net income for each accounting period until the reserve equals 50 percent of KEPCO’s common stock. The legal reserve is not available for cash dividends; however, this reserve may be credited to paid-in
Voluntary reserves	Details of voluntary reserves as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Reserve for investment on social overhead capital ￦ 5,277,449 5,277,449 Reserve for research and human development(*) 330,000 330,000 Reserve for business expansion 26,029,826 29,016,395 Reserve for equalizing dividends 210,000 210,000 ￦ 31,847,275 34,833,844 (*) The reserve for research and human development is appropriated by KEPCO to use as qualified tax credits to reduce corporate tax liabilities. The reserve is available for cash dividends for a certain period as defined by the Restriction of Special Taxation Act of Korea.
Changes in Retained Earnings	Changes in retained earnings for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ 48,187,241 53,173,871 Net profit for the period attributed to owner of the Company 7,048,581 1,298,720 Changes in equity method retained earnings (2,532 ) 10,065 Remeasurements of defined benefit liability, net of tax (69,330 ) 158,991 Dividend paid (1,990,089 ) (1,271,089 ) Ending balance ￦ 53,173,871 53,370,558
Dividends Paid	2015 In millions of won Number of shares issued Number of treasury stocks Number of shares eligible for dividends Dividends paid per share Dividends paid (In won) Common shares 641,964,077 — 641,964,077 ￦ 500 320,982 2016 In millions of won Number of shares issued Number of treasury stocks Number of shares eligible for dividends Dividends paid per share Dividends paid (In won) Common shares 641,964,077 — 641,964,077 ￦ 3,100 1,990,089 2017 In millions of won Number of shares issued Number of treasury stocks Number of shares eligible for dividends Dividends paid per share Dividends paid (In won) Common shares 641,964,077 — 641,964,077 ￦ 1,980 1,271,089
Changes in retained earnings of investments in associates and joint ventures	2016 2017 In millions of won Beginning balance ￦ (2,411 ) (4,943 ) Changes (2,532 ) 10,065 Ending balance ￦ (4,943 ) 5,122
Changes in retained earnings of remeasurement components	Changes in remeasurement components for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Beginning balance ￦ (202,878 ) (222,997 ) Changes (119,316 ) 239,636 Income tax effect 49,986 (80,645 ) Transfer to reserve for business expansion 49,211 20,493 Ending balance ￦ (222,997 ) (43,513 )

Statement of Appropriation of90

Statement of Appropriation of Retained Earnings (Tables)	12 Months Ended
	Dec. 31, 2017
Statement of Appropriation of Retained Earnings [Abstract]
Statement of Appropriation of Retained Earnings	For the year ended December 31, 2016, KEPCO’s retained earnings were appropriated on March 21, 2017. For the year ended December 31, 2017, KEPCO’s retained earnings were appropriated on March 30, 2018. Statements of appropriation of retained earnings of KEPCO, the controlling company, for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won except for I.   Retained earnings before appropriations Unappropriated retained earnings carried over from prior years ￦ — — Net income 4,261,986 1,506,852 Remeasurements of the defined benefit plan (4,328 ) 72,723 4,257,658 1,579,575 II. Transfer from voluntary reserves — — III.  Subtotal (I+II) 4,257,658 1,579,575 IV.  Appropriations of retained earnings (4,257,658 ) (1,579,575 ) Legal reserve — — Dividends (government, individual) Amount of dividends per share (%) : Current year—￦ 790 (16%) Prior year—￦ 1,980 (40%) (1,271,089 ) (507,152 ) Reserve for business expansion (2,986,569 ) (1,072,423 ) V. Unappropriated retained earnings to be carried over forward to subsequent year — —

Hybrid Bonds (Tables)

Hybrid Bonds (Tables)	12 Months Ended
	Dec. 31, 2017
Hybrid Bonds [Abstract]
Hybrid Bonds	Hybrid bonds classified as equity (non-controlling Issuer Hybrid bond Issued date Maturity Yield (%) 2016 2017 In millions of won Korea Western Power Co., Ltd. 1st hybrid bond 2012.10.18 — — ￦ 100,000 — Korea South-East Power Co., Ltd. 1st hybrid bond 2012.12.07 2042.12.06 4.38 170,000 170,000 Korea South-East Power Co., Ltd. 2nd hybrid bond 2012.12.07 2042.12.06 4.44 230,000 230,000 Expense of issuance (1,340 ) (1,090 ) ￦ 498,660 398,910

Other Components of Equity (Tab

Other Components of Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Other Components of Equity [Abstract]
Other Components of Equity	Other components of equity of the parent as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Other capital surplus ￦ 1,235,146 1,233,793 Accumulated other comprehensive loss (33,875 ) (271,457 ) Other equity 13,294,973 13,294,973 ￦ 14,496,244 14,257,309
Changes in other capital surplus	Changes in other capital surplus for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 Gains on Treasury stocks Others Subtotal Gains on disposal of treasury stocks Others Subtotal In millions of won Beginning balance ￦ 387,524 809,864 1,197,388 387,524 847,622 1,235,146 Disposal of subsidiary — 36,008 36,008 — — — Issuance of share capital of subsidiary — 1,750 1,750 — (1,378 ) (1,378 ) Others — — — — 25 25 Ending balance ￦ 387,524 847,622 1,235,146 387,524 846,269 1,233,793
Changes in accumulated other comprehensive income (loss)	Changes in accumulated other comprehensive income (loss) for the years ended December 31, 2016 and 2017 are as follows: 2016 Available-for-sale financial asset valuation reserve Shares in other Income (loss) of investments in associates and Reserve for overseas translation credit Reserve for derivatives Total In millions of won Beginning balance ￦ (24,905 ) 276,373 (254,462 ) (95,719 ) (98,713 ) Changes in the unrealized fair value of available-for-sale 61,275 — — — 61,275 Shares in other comprehensive loss of associates and joint ventures, net of tax — (54,918 ) — — (54,918 ) Foreign currency translation of foreign operations, net of tax — — 31,406 — 31,406 Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax — — — 27,075 27,075 Ending balance ￦ 36,370 221,455 (223,056 ) (68,644 ) (33,875 ) 2017 Available-for-sale financial asset valuation reserve Shares in other Income (loss) of investments in associates and Reserve for overseas translation credit Reserve for gain (loss) on derivatives Total In millions of won Beginning balance ￦ 36,370 221,455 (223,056 ) (68,644 ) (33,875 ) Changes in the unrealized fair value of available-for-sale (7,102 ) — — — (7,102 ) Shares in other comprehensive loss of associates and joint ventures, net of tax — (154,991 ) — — (154,991 ) Foreign currency translation of foreign operations, net of tax — — (95,103 ) — (95,103 ) Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax — — — 19,614 19,614 Ending balance ￦ 29,268 66,464 (318,159 ) (49,030 ) (271,457 )
Changes in other equity	2016 2017 In millions of won Statutory revaluation reserve ￦ 13,295,098 13,295,098 Changes in other equity (125 ) (125 ) ￦ 13,294,973 13,294,973

Sales (Tables)

Sales (Tables)	12 Months Ended
	Dec. 31, 2017
Revenue [Abstract]
Sales	of sales for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 Domestic Overseas Domestic Overseas Domestic Overseas In millions of won Sales of goods ￦ 53,961,463 405,573 54,982,095 397,392 55,373,316 399,232 Electricity 53,229,470 — 54,304,529 — 54,649,882 — Heat supply 204,987 — 181,597 — 205,838 — Others 527,006 405,573 495,969 397,392 517,596 399,232 Sales of service 209,189 244,298 195,697 161,046 186,990 164,167 Sales of construction services 180,424 3,580,780 132,219 3,894,638 92,501 3,119,683 ￦ 54,351,076 4,230,651 55,310,011 4,453,076 55,652,807 3,683,082

Selling and Administrative Ex94

Selling and Administrative Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Selling, general and administrative expense [Abstract]
Selling and Administrative Expenses	2015 2016 2017 In millions of won Salaries ￦ 655,432 734,930 735,383 Retirement benefit expense 61,903 72,812 71,094 Welfare and benefit expense 119,866 162,243 179,406 Insurance expense 10,636 11,513 15,414 Depreciation 102,867 169,431 190,245 Amortization of intangible assets 40,465 35,171 44,990 Bad debt expense 290 38,719 126,714 Commission 562,171 605,879 673,740 Advertising expense 30,085 34,658 114,519 Training expense 4,988 6,314 7,027 Vehicle maintenance expense 10,529 10,390 9,998 Publishing expense 3,124 3,643 3,672 Business promotion expense 3,338 3,477 3,700 Rent expense 44,905 40,020 38,380 Telecommunication expense 22,678 25,448 24,916 Transportation expense 753 596 495 Taxes and dues 55,970 46,531 48,395 Expendable supplies expense 7,272 6,834 7,731 Water, light and heating expense 9,558 9,720 10,545 Repairs and maintenance expense 74,330 75,122 63,477 Ordinary development expense 178,472 188,063 211,417 Travel expense 14,388 16,115 16,658 Clothing expense 5,751 8,273 8,410 Survey and analysis expense 590 666 698 Membership fee 1,040 1,132 1,122 Others 131,860 331,532 154,709 ￦ 2,153,261 2,639,232 2,762,855
Other selling and administrative expenses	Other selling and administrative expenses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Accommodation development expenses ￦ 28,134 186,896 55,799 Miscellaneous wages 43,109 31,907 32,300 Litigation and filing expenses 10,670 12,328 11,881 Compensation for damages 9,032 60,341 12,297 Outsourcing expenses 2,865 3,530 2,647 Reward expenses 2,472 3,267 2,786 Overseas market development expenses 1,541 2,177 1,876 Others 34,037 31,086 35,123 ￦ 131,860 331,532 154,709

Other Income and Expense (Table

Other Income and Expense (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of other operating income (expense) [Abstract]
Other Income	Other income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Reversal of other provisions ￦ 6,355 22,034 35,265 Reversal of other allowance for doubtful accounts 413 5,489 2,166 Gains on government grants 204 111 430 Gains on assets contributed 9,004 12,254 4,218 Gains on liabilities exempted 2,588 1,959 3,166 Compensation and reparations revenue 166,355 114,530 89,196 Revenue from research contracts 5,342 13,143 12,580 Income related to transfer of assets from customers 375,995 427,297 478,973 Rental income 196,406 211,580 192,136 Others 45,552 31,787 50,988 ￦ 808,214 840,184 869,118
Details of others of other income	Details of others of other income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Refund of claim for rectification ￦ 7,623 8,722 9,655 Adjustment of research project 4,090 4,148 3,884 Maintenance expenses on lease building 324 354 135 Training expenses 4,774 4,478 3,045 Deposit redemption 430 991 34 Reversal of expenses on litigation 219 893 360 Revenue on royalty fee 2,739 2,486 2,888 Reimbursement of insurance fee 11,797 — 1,498 Gains on guarantee contracts 4,523 2,796 456 Others 9,033 6,919 29,033 ￦ 45,552 31,787 50,988
Other Expense	Other expense for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Compensation and indemnification expense ￦ 16,959 — 37 Accretion expenses of other provisions 4,575 4,556 7,535 Depreciation expenses on investment properties 669 678 1,176 Depreciation expenses on idle assets 6,698 6,639 6,644 Other bad debt expense 18,473 4,585 1,778 Donations 34,134 114,094 119,421 Others 27,340 58,072 43,464 ￦ 108,848 188,624 180,055
Details of others of other expense	Details of others of other expense for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Operating expenses related to the idle assets ￦ 779 459 136 Research grants 1,392 1,461 1,180 Supporting expenses on farming and fishing village 14,626 15,201 11,956 Operating expenses on fitness center 2,912 2,706 3,498 Expenses on adjustment of research and development grants 709 — 806 Taxes and dues 1,105 4,582 2,270 Expenses on R&D supporting 146 690 5,459 Moving expense 3,191 — — Others 2,480 32,973 18,159 ￦ 27,340 58,072 43,464

Other Gains (Losses) (Tables)

Other Gains (Losses) (Tables)	12 Months Ended
	Dec. 31, 2017
Other Gains (Losses) [Abstract]
Other Gains (Losses)	2015 2016 2017 In millions of won Other gains Gains on disposal of property, plant, and equipment ￦ 8,637,508 74,035 48,316 Gains on disposal of intangible assets 32 — 564 Reversal of impairment loss on intangible assets 275 3 54 Gains on foreign currency translation 13,784 15,311 20,485 Gains on foreign currency transaction 61,007 55,377 93,151 Gains on insurance proceeds 30 — 400 Others 162,128 187,792 269,562 Other losses Losses on disposal of property, plant and equipment (73,073 ) (42,715 ) (70,514 ) Losses on disposal of intangible assets (16 ) (158 ) (183 ) Impairment loss on property, plant and equipment (30,344 ) — (51,067 ) Impairment loss on intangible assets (22 ) (3,945 ) (20 ) Losses on foreign currency translation (15,097 ) (23,835 ) (25,495 ) Losses on foreign currency transaction (75,615 ) (72,058 ) (36,241 ) Others (69,824 ) (119,309 ) (92,385 ) ￦ 8,610,773 70,498 156,627
Details of others of other gains	2015 2016 2017 In millions of won Gains on disposal of inventories ￦ 10,758 9,494 6,024 Gains on valuation of inventories 7 2 — Gains on proxy collection of TV license fee 38,529 38,991 39,711 Gains on compensation of impaired electric poles — 3,650 1,526 Gains on compensation for infringement on contract 7,414 3,040 18,990 Gains on harbor facilities dues 5,943 2,957 3,025 Gains on technical fees 1,258 1,271 2,105 Reversal of occupation development training fees 1,878 1,756 1,697 Gains on disposal of waste 2,880 4,222 4,261 Gains on insurance 11,865 3,786 10,410 Gains on litigation 600 — — Gains on tax rebate 1,661 5,226 2,161 Gains on other commission 2,177 4,639 4,790 Gains on research tasks 1,446 10 — Gains on settlement and others 2,803 2,188 — Gains on sales of greenhouse gas emissions rights 52 46 — Others 72,857 106,514 174,862 ￦ 162,128 187,792 269,562
Details of others of other losses	2015 2016 2017 In millions of won Losses on valuation of inventories ￦ 1,318 2,683 3,875 Losses on disposal of inventories 13,469 3,092 3,273 Losses due to disaster 263 1,522 5,374 Losses on rounding adjustment of electric charge surtax 1,251 1,260 1,253 Losses on adjustments of levies 13,928 1,184 1 Forfeit of taxes and dues 190 4,582 656 Losses on litigation 488 2,581 — Others 38,917 102,405 77,953 ￦ 69,824 119,309 92,385

Finance Income (Tables)

Finance Income (Tables)	12 Months Ended
	Dec. 31, 2017
Finance income [Abstract]
Finance Income	Finance income for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Interest income ￦ 241,585 241,778 206,143 Dividends income 14,069 9,446 11,477 Gains on disposal of financial assets 4 1,482 1,130 Gains on valuation of Financial assets at fair value through profit or loss — — 12 Gains on valuation of derivatives 610,582 293,830 16,165 Gains on transaction of derivatives 151,851 45,549 29,257 Gains on foreign currency translation 127,372 161,905 1,115,832 Gains on foreign currency transaction 37,377 37,553 150,602 Other finance income 148 — — ￦ 1,182,988 791,543 1,530,618
Interest Income	2015 2016 2017 In millions of won Cash and cash equivalents ￦ 54,687 61,380 35,474 Available-for-sale 29 — 290 Held-to-maturity 99 97 82 Loans and receivables 28,586 25,106 30,014 Short-term financial instrument 46,921 45,763 29,412 Long-term financial instrument 10,492 7,195 8,144 Trade and other receivables 100,771 102,237 102,727 ￦ 241,585 241,778 206,143

Finance Expenses (Tables)

Finance Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Finance Expenses [Abstract]
Finance Expenses	Finance expenses for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Interest expense ￦ 2,015,684 1,752,868 1,789,552 Losses on sale of financial assets 3,008 9 2,343 Impairment of available-for-sale 84,370 86,703 2,713 Losses on valuation of derivatives 17,051 5,762 890,832 Losses on transaction of derivatives 37,262 101,987 198,218 Losses on foreign currency translation 743,283 406,849 207,944 Losses on foreign currency transaction 113,723 57,889 35,175 Losses on repayment of financial liabilities 33 23,000 5 Other 1,043 2,020 1,170 ￦ 3,015,457 2,437,087 3,127,952
Interest Expenses	2015 2016 2017 In millions of won Trade and other payables ￦ 84,527 68,375 57,160 Short-term borrowings 14,627 6,969 35,891 Long-term borrowings 103,503 91,584 87,011 Debt securities 2,177,855 1,922,900 1,698,232 Other financial liabilities 538,680 482,428 491,665 2,919,192 2,572,256 2,369,959 Less: Capitalized borrowing costs ￦ (903,508 ) (819,388 ) (580,407 ) 2,015,684 1,752,868 1,789,552

Income tax expense (Tables)

Income tax expense (Tables)	12 Months Ended
	Dec. 31, 2017
Income tax expense [Abstract]
Income tax expense	2015 2016 2017 In millions of won Current income tax expense Payment of income tax ￦ 2,682,779 2,689,640 881,583 Adjustment due to changes in estimates related to prior years (23,248 ) 231,113 4,484 Current income tax directly recognized in equity 37,768 30,059 (56,098 ) 2,697,299 2,950,812 829,969 Deferred income tax expense Generation and realization of temporary differences 48,878 509,762 1,283,012 Changes of unrecognized tax losses, tax credit and temporary differences for prior periods 71,999 (86,845 ) 44,573 Changes in deferred tax on tax losses carryforwards 2,374,237 — — Tax credit carryforwards 47,000 (8,588 ) 15,270 2,542,114 414,329 1,342,855 Income tax expense ￦ 5,239,413 3,365,141 2,172,824
Reconciliation between actual income tax expense and amount computed by applying the statutory tax rate	2015 2016 2017 In millions of won Income before income tax ￦ 18,655,786 10,513,468 3,614,218 Income tax expense computed at applicable tax rate of 24.2% 4,514,700 2,544,259 874,641 Adjustments Effect of applying gradual tax rate (4,147 ) (5,082 ) (5,082 ) Effect of non-taxable (8,047 ) (29,554 ) (32,032 ) Effect of non-deductible 17,734 22,258 15,032 Effects of tax credits and deduction (103,435 ) (194,731 ) (161,069 ) Recognition (reversal) of unrecognized deferred tax asset, net 71,999 (86,845 ) 44,573 Effect of change in deferred tax due to change in tax rate (from 24.2% to 27.5%) — — 1,055,154 Deferred income tax related to investments in subsidiaries and associates 784,793 862,956 394,145 Others, net (10,936 ) 20,767 (17,022 ) 747,961 589,769 1,293,699 Adjustment in respect of prior years due to change in estimate (23,248 ) 231,113 4,484 Income tax expense ￦ 5,239,413 3,365,141 2,172,824 Effective tax rate 28 % 32 % 60 %
Income tax directly adjusted to shareholders’ equity (except for accumulated other comprehensive income (loss))	Income tax directly adjusted to shareholders’ equity (except for accumulated other comprehensive income (loss)) for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 In millions of won Dividends of hybrid bond ￦ 5,253 5,253 5,248 Gain on disposal of investments in subsidiaries (14,144 ) (7,006 ) — Effect of change in effective tax rate — — (25 ) ￦ (8,891) (1,753 ) 5,223
Income tax recognized as other comprehensive income (loss)	2015 2016 2017 In millions of won Income tax recognized as other comprehensive income (loss) Loss on valuation of available-for-sale ￦ (6,315 ) (8,143 ) (2,551 ) Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax 7,253 (18,335 ) (11,016 ) Remeasurement of defined benefit obligations 42,913 49,986 (80,645 ) Investments in associates 13,648 7,731 8,649 Others (10,840 ) 573 24,242 ￦ 46,659 31,812 (61,321 )
Changes in deferred income tax assets (liabilities)	Changes in deferred income tax assets (liabilities) recognized in the statements of financial position for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning balance Amounts Amount Amounts recognized directly in equity Ending balance In millions of won Deferred income tax on temporary differences Employee benefits ￦ 407,342 36,003 49,986 — 493,331 Cash flow hedge (29,013 ) (6,235 ) (18,335 ) — (53,583 ) Investments in associates or subsidiaries (6,449,998 ) (717,072 ) 7,731 (7,006 ) (7,166,345 ) Property, plant and equipment (5,495,786 ) (31,532 ) — — (5,527,318 ) Finance lease (272,430 ) (73,001 ) — — (345,431 ) Intangible assets 9,420 (433 ) — — 8,987 Financial assets at fair value through profit or loss (4 ) (58 ) — — (62 ) Available-for-sale (49,199 ) (11,005 ) (8,143 ) — (68,347 ) Deferred revenue 215,361 (1,502 ) — — 213,859 Provisions 3,372,423 210,948 — — 3,583,371 Doubtful receivables 1,405 1,291 — — 2,696 Other finance liabilities 26,298 (1,302 ) — 5,253 30,249 Gains or losses on foreign exchange translation 128,714 10,224 — — 138,938 Allowance for doubtful accounts 18,976 (1,724 ) — — 17,252 Accrued income (11,231 ) 5,864 — — (5,367 ) Special deduction for property, plant and equipment (194,347 ) 38 — — (194,309 ) Reserve for research and human development (20,688 ) 7,805 — — (12,883 ) Others 576,585 118,712 573 — 695,870 (7,766,172 ) (452,979 ) 31,812 (1,753 ) (8,189,092 ) Deferred income tax on unused tax losses and tax credit Tax losses (3 ) 3 — — — Tax credit 27,115 8,588 — — 35,703 27,112 8,591 — — 35,703 ￦ (7,739,060 ) (444,388 ) 31,812 (1,753 ) (8,153,389 ) 2017 Beginning balance Amounts Amount Amounts recognized directly in equity Ending balance In millions of won Deferred income tax on temporary differences Employee benefits ￦ 493,331 86,008 (80,645 ) — 498,694 Cash flow hedge (53,583 ) 130,044 (11,016 ) — 65,445 Investments in associates or subsidiaries (7,166,345 ) (1,510,295 ) 8,649 (25 ) (8,668,016 ) Property, plant and equipment (5,527,318 ) (1,333,122 ) — — (6,860,440 ) Finance lease (345,431 ) (81,518 ) — — (426,949 ) Intangible assets 8,987 (1,339 ) — — 7,648 Financial assets at fair value through profit or loss (62 ) 952 — — 890 Available-for-sale (68,347 ) 62,055 (2,551 ) — (8,843 ) Deferred revenue 213,859 16,852 — — 230,711 Provisions 3,583,371 1,239,462 — — 4,822,833 Doubtful receivables 2,696 (2,637 ) — — 59 Other finance liabilities 30,249 (2,742 ) — 5,248 32,755 Gains or losses on foreign exchange translation 138,938 (140,292 ) — — (1,354 ) Allowance for doubtful accounts 17,252 25,679 — — 42,931 Accrued income (5,367 ) 3,542 — — (1,825 ) Special deduction for property, plant and equipment (194,309 ) (6,618 ) — — (200,927 ) Reserve for research and human development (12,883 ) 9,842 — — (3,041 ) Others 695,870 232,642 24,242 — 952,754 (8,189,092 ) (1,271,485 ) (61,321 ) 5,223 (9,516,675 ) Deferred income tax on unused tax losses and tax credit Tax losses — — — — — Tax credit 35,703 (15,272 ) — — 20,431 35,703 (15,272 ) — — 20,431 ￦ (8,153,389 ) (1,286,757 ) (61,321 ) 5,223 (9,496,244 )
Deferred income tax assets (liabilities)	2016 2017 In millions of won Deferred income tax assets ￦ 795,131 919,153 Deferred income tax liabilities (8,948,520 ) (10,415,397 ) ￦ (8,153,389 ) (9,496,244 )
Details of deductible temporary differences, tax losses and unused tax credits for which no deferred income tax assets were recognized	2016 2017 In millions of won Deductible temporary differences ￦ 426,718 444,426

Assets Held-for-Sale (Tables)

Assets Held-for-Sale (Tables)	12 Months Ended
	Dec. 31, 2017
Assets Held-for-Sale [Abstract]
Assets Held-for-Sale	Assets held-for-sale 2016 2017 In millions of won Land(*1) ￦ 2,907 2,765 Building(*1) 20,366 19,369 Investments in associates(*2, 3, 4) 42,569 5,837 ￦ 65,842 27,971 (*1) The board of directors of KEPCO Engineering & Construction Company, Inc., a subsidiary of the Company, determined to dispose the office building in Yongin as part of the government’s plan to relocate state-run held-for-sale. (*2) Korea Western Power Co., Ltd., a subsidiary of the Company, planned to dispose certain portion of its investment in Dongducheon Dream Power Co., Ltd. and had classified the relevant book value as non-current held-for-sale. (*3) Korea Hydro & Nuclear Power Co., Ltd., a subsidiary of the Company, initiated efforts to sell its shares in Yeongwol Energy Station Co., Ltd. during the year ended December 31, 2016. KHNP won the first trial of the lawsuit against the counterparty on November 2, 2017. However, the planned sale period has been extended since the appeal is ongoing as of December 31, 2017. The Company expects the sale to occur in 2018. (*4) KEPCO Engineering & Construction Company, Inc., a subsidiary of the Company, exercised a put option to sell the shares of DS POWER Co., Ltd. on December 11, 2017 and the shares are expected to be sold on February 28, 2018. Thus, the Company reclassified the relevant book value to assets held-for-sale.

Expenses Classified by Nature (

Expenses Classified by Nature (Tables)	12 Months Ended
	Dec. 31, 2017
Expenses Classified by Nature [Abstract]
Expenses Classified by Nature	Expenses classified by nature for the years ended December 31, 2015, 2016 and 2017 are as follows: 2015 Selling and Cost of sales Total In millions of won Raw materials used ￦ — 14,626,933 14,626,933 Salaries 655,432 2,962,476 3,617,908 Retirement benefit expense 61,903 320,700 382,603 Welfare and benefit expense 119,866 426,186 546,052 Insurance expense 10,636 83,910 94,546 Depreciation 102,867 8,158,884 8,261,751 Amortization of intangible assets 40,465 31,801 72,266 Bad debt expense 290 — 290 Commission 562,171 353,703 915,874 Advertising expense 30,085 8,498 38,583 Training expense 4,988 11,186 16,174 Vehicle maintenance expense 10,529 8,323 18,852 Publishing expense 3,124 3,981 7,105 Business promotion expense 3,338 4,312 7,650 Rent expense 44,905 142,054 186,959 Telecommunication expense 22,678 73,180 95,858 Transportation expense 753 5,336 6,089 Taxes and dues 55,970 397,161 453,131 Expendable supplies expense 7,272 29,874 37,146 Water, light and heating expense 9,558 26,870 36,428 Repairs and maintenance expense 74,330 1,771,760 1,846,090 Ordinary development expense 178,472 432,748 611,220 Travel expense 14,388 52,910 67,298 Clothing expense 5,751 4,135 9,886 Survey and analysis expense 590 3,071 3,661 Membership fee 1,040 6,401 7,441 Power purchase — 11,428,027 11,428,027 Others 131,860 4,083,309 4,215,169 ￦ 2,153,261 45,457,729 47,610,990 2016 Selling and Cost of sales Total In millions of won Raw materials used ￦ — 13,470,586 13,470,586 Salaries 734,930 3,425,712 4,160,642 Retirement benefit expense 72,812 374,826 447,638 Welfare and benefit expense 162,243 507,691 669,934 Insurance expense 11,513 79,987 91,500 Depreciation 169,431 8,704,525 8,873,956 Amortization of intangible assets 35,171 44,544 79,715 Bad debt expense 38,719 — 38,719 Commission 605,879 423,179 1,029,058 Advertising expense 34,658 9,693 44,351 Training expense 6,314 13,347 19,661 Vehicle maintenance expense 10,390 7,016 17,406 Publishing expense 3,643 4,615 8,258 Business promotion expense 3,477 4,836 8,313 Rent expense 40,020 133,670 173,690 Telecommunication expense 25,448 75,925 101,373 Transportation expense 596 5,153 5,749 Taxes and dues 46,531 464,962 511,493 Expendable supplies expense 6,834 34,668 41,502 Water, light and heating expense 9,720 25,820 35,540 Repairs and maintenance expense 75,122 1,896,656 1,971,778 Ordinary development expense 188,063 517,441 705,504 Travel expense 16,115 63,611 79,726 Clothing expense 8,273 5,363 13,636 Survey and analysis expense 666 3,209 3,875 Membership fee 1,132 8,714 9,846 Power purchase — 10,755,739 10,755,739 Others 331,532 4,488,065 4,819,597 ￦ 2,639,232 45,549,553 48,188,785 2017 Selling and Cost of sales Total In millions of won Raw materials used ￦ — 15,924,707 15,924,707 Salaries 735,383 3,479,591 4,214,974 Retirement benefit expense 71,094 397,852 468,946 Welfare and benefit expense 179,406 543,738 723,144 Insurance expense 15,414 90,677 106,091 Depreciation 190,245 9,461,974 9,652,219 Amortization of intangible assets 44,990 68,682 113,672 Bad debt expense 126,714 — 126,714 Commission 673,740 469,695 1,143,435 Advertising expense 114,519 10,917 125,436 Training expense 7,027 14,362 21,389 Vehicle maintenance expense 9,998 7,468 17,466 Publishing expense 3,672 4,248 7,920 Business promotion expense 3,700 4,973 8,673 Rent expense 38,380 148,509 186,889 Telecommunication expense 24,916 73,956 98,872 Transportation expense 495 9,145 9,640 Taxes and dues 48,395 437,643 486,038 Expendable supplies expense 7,731 31,994 39,725 Water, light and heating expense 10,545 30,150 40,695 Repairs and maintenance expense 63,477 2,047,943 2,111,420 Ordinary development expense 211,417 510,020 721,437 Travel expense 16,658 69,015 85,673 Clothing expense 8,410 4,985 13,395 Survey and analysis expense 698 3,661 4,359 Membership fee 1,122 8,482 9,604 Power purchase — 14,264,331 14,264,331 Others 154,709 3,980,137 4,134,846 ￦ 2,762,855 52,098,855 54,861,710

Earnings per share (Tables)

Earnings per share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings per share [Abstract]
Basic earnings per share	Basic earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In won Basic earnings per share ￦ 20,701 10,980 2,023
Diluted earnings per share	Type 2015 2016 2017 In won Diluted earnings per share ￦ 20,701 10,980 2,023
Calculation of Basic earnings per share	Net profit for the period and weighted average number of common shares used in the calculation of basic earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In millions of won except number of shares Net profit attributable to controlling interest ￦ 13,289,127 7,048,581 1,298,720 Profit used in the calculation of total basic earnings per share 13,289,127 7,048,581 1,298,720 Weighted average number of common shares 641,964,077 641,964,077 641,964,077
Calculation of Diluted earnings per share	Earnings used in the calculation of total diluted earnings per share for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In millions of won Profit used in the calculation of total diluted earnings per share ￦ 13,289,127 7,048,581 1,298,720 Weighted average common shares used in calculating diluted earnings per share are adjusted from weighted average common shares used in calculating basic earnings per share. Detailed information of the adjustment for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In number of shares Weighted average number of common shares 641,964,077 641,964,077 641,964,077 Diluted weighted average number of shares 641,964,077 641,964,077 641,964,077

Risk Management (Tables)

Risk Management (Tables)	12 Months Ended
	Dec. 31, 2017
Risk Management [Abstract]
Capital risk management	Details of the Company’s capital management accounts as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Total borrowings and debt securities ￦ 53,639,205 54,747,392 Cash and cash equivalents 3,051,353 2,369,739 Net borrowings and debt securities 50,587,852 52,377,653 Total shareholder’s equity 73,050,545 72,964,641 Debt to equity ratio 69.25 % 71.78 %
Credit risk management	Book values of the financial assets represent the maximum exposed amounts of the credit risk. Details of the Company’s level of maximum exposure to credit risk as of December 31, 2016 and 2017 are as follows: 2016 2017 In millions of won Cash and cash equivalents ￦ 3,051,353 2,369,739 Derivative assets (trading) 367,477 22,020 Available-for-sale 1,014,732 699,833 Held-to-maturity 3,244 3,144 Loans and receivables 834,207 905,641 Long-term/short-term financial instruments 2,695,926 2,244,514 Financial assets at fair value through profit or loss — 111,512 Derivative assets (using hedge accounting) 413,897 10,606 Trade and other receivables 9,692,391 9,683,769 Financial guarantee contracts(*) 1,396,152 1,154,862 (*) Maximum exposure associated with the financial guarantee contracts is the maximum amounts of the obligation.
Sensitivity analysis of Defined benefit obligation	A sensitivity analysis of defined benefit obligation assuming a 1% increase and decrease movements in the actuarial valuation assumptions as of December 31, 2016 and 2017 are as follows: 2016 2017 Type Accounts 1% Increase 1% Decrease 1% Increase 1% Decrease In millions of won Future salary increases Increase (decrease) in defined benefit obligation ￦ 344,874 (304,685 ) 354,852 (305,494 ) Discount rate Increase (decrease) in defined benefit obligation (305,031 ) 371,689 (313,597 ) 377,148
Changes in provisions due to movements in underlying assumptions	Changes in provisions due to movements in underlying assumptions as of December 31, 2016 and 2017 are as follows: Type Accounts 2016 2017 PCBs Inflation rate 1.29 % 1.23 % Discount rate 2.77 % 2.55 % Nuclear plants Inflation rate 1.40 % 1.21 % Discount rate 3.55 % 2.94 % Spent fuel Inflation rate 2.93 % 2.93 % Discount rate 4.49 % 4.49 %
Sensitivity analysis of Provisions due to movements in underlying assumptions	A sensitivity analysis of provisions assuming a 0.1% increase and decrease movements in the underlying assumptions as of December 31, 2016 and 2017 are as follows: 2016 2017 Type Accounts 0.1% Increase 0.1% Decrease 0.1% Increase 0.1% Decrease In millions of won Discount rate PCBs ￦ (817 ) 822 (811 ) 816 Nuclear plants (209,277 ) 215,139 (262,949 ) 270,370 Spent fuel (52,353 ) 54,387 (51,015 ) 52,997 Inflation rate PCBs 834 (830 ) 826 (822 ) Nuclear plants 240,115 (233,553 ) 287,926 (280,249 ) Spent fuel 55,173 (53,182 ) 53,763 (51,823 )
Foreign currency risk	The Company undertakes transactions denominated in foreign currencies; consequently, exposures to exchange rate fluctuations arise. The carrying amounts of the Company’s foreign currency denominated monetary assets and monetary liabilities as of December 31, 2016 and 2017 are as follows: Assets Liabilities Type 2016 2017 2016 2017 In thousands of foreign currencies AED 7,479 5,693 1,534 2,049 AUD 187 145 632,613 652,259 BDT 49,110 60,208 833 1,001 BWP 4,296 797 3,222 — CAD — 82 — 171 CHF — — 400,308 400,004 CNY — 13,007 — 26,140 EUR 17,585 5,708 14,111 68,003 GBP 3 3 110 2,327 IDR 52,568 167,775 — — INR 1,059,092 1,228,259 161,631 227,078 JOD 1,746 1,624 5 5 JPY 520,746 799,501 20,442,504 21,624,128 KZT 12,157 359 — — MGA 3,408,579 2,762,572 150,430 319,581 NOK — — — 482 PHP 415,818 189,261 136,700 125,431 PKR 274,090 251,190 5,051 4,676 SAR 1,149 1,191 — 44 SEK — — — 449,002 USD 1,319,524 1,653,858 9,445,567 8,321,335 UYU 1,307 12,955 586 10,586 ZAR 386 361 75 4
Sensitivity analysis of Foreign currency risk	A sensitivity analysis on the Company’s income for the period assuming a 10% increase and decrease in currency exchange rates as of December 31, 2016 and 2017 are as follows: 2016 2017 Type 10% Increase 10% Decrease 10% Increase 10% Decrease In millions of won Increase (decrease) of income before ￦ (1,101,372 ) 1,101,372 (844,122 ) 844,122 Increase (decrease) of shareholder’s (1,101,372 ) 1,101,372 (844,122 ) 844,122 (*) The effect on the shareholders’ equity excluding the impact of income taxes.
Interest rate risk	The Company’s borrowings and debt securities with floating interest rates as of December 31, 2016 and 2017 are as follows: Type 2016 2017 In millions of won Short-term borrowings ￦ 289,322 290,873 Long-term borrowings 1,459,969 1,743,252 Debt securities 1,518,500 685,700 ￦ 3,267,791 2,719,825
Sensitivity analysis of Interest rate risk	A sensitivity analysis on the Company’s long-term borrowings and debt securities assuming a 1% increase and decrease in interest rates, without consideration of hedge effect of related derivatives for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 Type 1% Increase 1% Decrease 1% Increase 1% Decrease In millions of won Increase (decrease) of profit before income tax ￦ (32,678 ) 32,678 (27,198 ) 27,198 Increase (decrease) of shareholder’s equity(*) (32,678 ) 32,678 (27,198 ) 27,198 (*) The effect on the shareholders’ equity excluding the impact of income taxes.
Electricity rates risk	A sensitivity analysis on the Company’s income for the period assuming a 1% increase and decrease in price of electricity for the years ended December 31, 2016 and 2017 are as follows: 2016 2017 Type 1% Increase 1% Decrease 1% Increase 1% Decrease In millions of won Increase (decrease) of profit before income tax ￦ 543,045 (543,045 ) 546,499 (546,499 ) Increase (decrease) of shareholder’s equity(*) 543,045 (543,045 ) 546,499 (546,499 ) (*) The effect on the shareholders’ equity excluding the impact of income taxes.
Details of maturities of non-derivative financial liabilities	The following table shows the details of maturities of non-derivative non-derivative 2016 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Borrowings and debt securities ￦ 10,613,185 9,786,209 19,353,498 24,461,835 64,214,727 Finance lease liabilities 175,512 174,534 229,495 152,247 731,788 Trade and other payables 5,464,234 307,222 660,426 2,170,525 8,602,407 Financial guarantee contracts(*) 249,200 40,617 865,842 240,493 1,396,152 ￦ 16,502,131 10,308,582 21,109,261 27,025,100 74,945,074 2017 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Borrowings and debt securities ￦ 10,748,437 7,948,320 21,331,394 22,694,867 62,723,018 Finance lease liabilities 174,534 87,709 185,284 108,749 556,276 Trade and other payables 5,867,729 301,165 698,289 1,937,558 8,804,741 Financial guarantee contracts(*) 7,081 18,054 1,049,667 80,060 1,154,862 ￦ 16,797,781 8,355,248 23,264,634 24,821,234 73,238,897 (*) This represents the total guarantee amounts associated with the financial guarantee contracts. Financial guarantee liabilities which are recognized as of December 31, 2016 and 2017 are ￦29,665 million and ￦23,475 million, respectively.
The expected maturities for non-derivative financial assets	The expected maturities for non-derivative 2016 Type Less than 1 year 1~5 Years More than 5 years Other(*) Total In millions of won Cash and cash equivalents ￦ 3,051,353 — — — 3,051,353 Available-for-sale — — — 1,014,732 1,014,732 Held-to-maturity 114 3,126 4 — 3,244 Loans and receivables 198,133 233,564 439,666 5,591 876,954 Long-term/short-term financial instruments 2,281,460 200,001 214,122 343 2,695,926 Trade and other receivables 7,790,953 915,679 919,901 74,199 9,700,732 ￦ 13,322,013 1,352,370 1,573,693 1,094,865 17,342,941 2017 Type Less than 1 year 1~5 Years More than 5 years Other(*) Total In millions of won Cash and cash equivalents ￦ 2,369,739 — — — 2,369,739 Available-for-sale — — 214,156 485,677 699,833 Held-to-maturity 5 3,139 — — 3,144 Loans and receivables 244,309 261,672 429,628 10,821 946,430 Long-term/short-term financial instruments 1,702,084 201,821 340,304 305 2,244,514 Financial assets at fair value through profit or loss — — 111,512 — 111,512 Trade and other receivables 7,930,715 920,539 788,795 52,031 9,692,080 ￦ 12,246,852 1,387,171 1,884,395 548,834 16,067,252 (*) The maturities cannot be presently determined.
Derivative liabilities classified by maturity periods which from reporting date to maturity date of contract	Derivative liabilities classified by maturity periods which from reporting date to maturity date of contract as of December 31, 2016 and 2017 are as follows: 2016 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Gross settlement —Trading ￦ (3,081 ) (24,044 ) — (2,799 ) (29,924 ) —Hedging (2,645 ) (2,645 ) (56,484 ) (56,575 ) (118,349 ) ￦ (5,726 ) (26,689 ) (56,484 ) (59,374 ) (148,273 ) 2017 Type Less than 1 year 1~2 Years 2~5 Years More than 5 years Total In millions of won Net settlement —Trading ￦ (774 ) — — — (774 ) Gross settlement —Trading (51,496 ) (19,887 ) (16,597 ) (4,967 ) (92,947 ) —Hedging (17,547 ) (28,977 ) (192,205 ) (44,137 ) (282,866 ) ￦ (69,817 ) (48,864 ) (208,802 ) (49,104 ) (376,587 )
Fair value and book value of financial assets and liabilities	2016 2017 Type Book value Fair value Book value Fair value In millions of won Assets recognized at fair value Available-for-sale ￦ 1,014,732 1,014,732 699,833 699,833 Derivative assets (trading) 367,477 367,477 22,020 22,020 Derivative assets (using hedge accounting) 413,897 413,897 10,606 10,606 Long-term financial instruments 414,466 414,466 542,430 542,430 Short-term financial instruments 2,281,460 2,281,460 1,702,084 1,702,084 Financial assets at fair value through profit or loss — — 111,512 111,512 4,492,032 4,492,032 3,088,485 3,088,485 Assets carried at amortized cost Held-to-maturity 3,244 3,244 3,144 3,144 Loans and receivables 834,207 834,207 905,641 905,641 Trade and other receivables 9,692,391 9,692,391 9,683,769 9,683,769 Cash and cash equivalents 3,051,353 3,051,353 2,369,739 2,369,739 13,581,195 13,581,195 12,962,293 12,962,293 Liabilities recognized at fair value Derivative liabilities (trading) 21,529 21,529 150,929 150,929 Derivative liabilities (using hedge accounting) 117,157 117,157 277,130 277,130 138,686 138,686 428,059 428,059 Liabilities carried at amortized cost Secured borrowings 744,565 744,565 1,055,554 1,055,554 Unsecured bond 50,749,793 54,455,659 51,146,783 53,436,659 Finance lease liabilities 541,179 541,179 418,260 418,260 Unsecured borrowings 2,089,885 2,099,574 2,476,196 2,477,055 Trade and other payables(*2) 8,602,407 8,602,407 8,804,741 8,804,741 Bank overdraft 54,962 54,962 68,859 68,859 ￦ 62,782,791 66,498,346 63,970,393 66,261,128 (*1) Book values of equity securities held by the Company that were measured at cost as of December 31, 2016 and 2017 are ￦138,557 million and ￦37,926 million, respectively, as a quoted market price does not exist in an active market and its fair value cannot be measured reliably. (*2) Excludes finance lease liabilities.
Interest rates used for determining fair value	The discount rate used for calculating fair value as of December 31, 2016 and 2017 are as follows: Type 2016 2017 Derivatives 0.02% ~ 4.16% 0.03% ~ 4.16% Borrowings and debt securities 0.02% ~ 4.38% 0.08% ~ 4.38% Finance lease 9.00% ~ 10.83% 9.00% ~ 10.83%
Fair value hierarchy	Fair values of financial instruments by hierarchy level as of December 31, 2016 and 2017 are as follows: 2016 Type Level 1 Level 2 Level 3 Total In millions of won Financial assets at fair value Available-for-sale ￦ 268,171 437,015 269,461 974,647 Derivative assets — 770,851 10,523 781,374 268,171 1,207,866 279,984 1,756,021 Financial liabilities at fair value Derivative liabilities — 138,686 — 138,686 2017 Type Level 1 Level 2 Level 3 Total In millions of won Financial assets at fair value Available-for-sale ￦ 274,453 214,156 173,298 661,907 Derivative assets — 18,466 14,160 32,626 Financial assets at fair value through profit or loss — 111,512 — 111,512 274,453 344,134 187,458 806,045 Financial liabilities at fair value Derivative liabilities — 428,059 — 428,059
Changes of financial assets and liabilities which are classified as level 3	Changes of financial assets and liabilities which are classified as level 3 for the years ended December 31, 2016 and 2017 are as follows: 2016 Beginning Acquisition Reclassified Valuation Disposal Foreign Ending In millions of won Financial assets at fair value Available-for-sale Unlisted securities ￦ 180,390 — 98,472 (9,401 ) — — 269,461 2017 Beginning Acquisition Reclassified Valuation Disposal Foreign Ending In millions of won Financial assets at fair value Available-for-sale Unlisted securities ￦ 269,461 — (92,128 ) (6,201 ) — 2,166 173,298

Service Concession Arrangeme104

Service Concession Arrangements (Tables)	12 Months Ended
	Dec. 31, 2017
Service Concession Arrangements [Abstract]
Gas Complex Thermal Power Plant at Ilijan, Philippines	Type Amounts In millions of won Less than 1 year ￦ 111,912 1 ~ 2 years 111,912 2 ~ 3 years 111,912 Over 3 years 158,543 ￦ 494,279
Hydroelectric Power Generation at Semangka, Indonesia	The Company’s expected future collections of service concession arrangements as of December 31, 2017 are as follows: Type Amounts In millions of won Less than 1 year ￦ 20,332 1 ~ 2 years 26,888 2 ~ 3 years 26,888 Over 3 years 591,687 ￦ 665,795

Related parties (Tables)

Related parties (Tables)	12 Months Ended
	Dec. 31, 2017
Related Parties [Abstract]
Related Party Transactions	<Sales and Others> Sales and others Company name Transaction type 2015 2016 2017 In millions of won <Associates> Daegu Green Power Co., Ltd. Electricity sales ￦ 1,055 — — Dongducheon Dream Power Co., Ltd. Electricity sales 14,811 15,221 17,041 Korea Gas Corporation Electricity sales 90,480 89,030 88,011 Daegu Photovoltaic Co., Ltd. Service — — 349 Jeongam Wind Power Co., Ltd. Electricity sales 8 6 30 Korea Power Engineering Service Co., Ltd. Service 1,743 1,455 1,317 KS Solar Co., Ltd. Electricity sales 21 20 5 Heang Bok Do Si Photovoltaic Power Co., Ltd. Service 1 2 2 Korea Electric Power Industrial Development Co., Ltd. Service 12,361 10,723 14,044 Goseong Green Energy Co., Ltd. Electricity sales 9,306 9,195 24,069 Gangneung Eco Power Co., Ltd. Service 9,761 5,223 2,391 Shin Pyeongtaek Power Co., Ltd. Electricity sales 11,344 3,579 9,025 Naepo Green Energy Co., Ltd. Electricity sales 66 104 185 Noeul Green Energy Co., Ltd. Electricity sales ￦ 45 177 32 Samcheok Eco Materials Co., Ltd. Electricity sales — 64 237 YTN Co., Ltd. Electricity sales 1,753 1,785 1,987 Busan Green Energy Co., Ltd. Service 1 133 120 Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) Electricity sales — 6 — Korea Electric Vehicle Charging Service Electricity sales 2 89 700 Ulleungdo Natural Energy Co., Ltd. Service 229 691 1,013 Tamra Offshore Wind Power Co., Ltd. Service — 12 55 Daegu clean Energy Co., Ltd. Electricity sales — — 421 Cheongna Energy Co., Ltd. Service 21,081 6,831 7,980 Gangwon Wind Power Co., Ltd. Electricity sales 1,046 1,273 994 Hyundai Green Power Co., Ltd. Design service 15,401 14,835 14,280 Korea Power Exchange Service 4,272 7,141 8,446 Hyundai Energy Co., Ltd. Service 25,402 24,719 15,627 Taebaek Wind Power Co., Ltd. Service 872 796 813 Pyeongchang Wind Power Co., Ltd. Design service 72 497 1,176 Daeryun Power Co., Ltd. Electricity sales 1,731 1,516 1,796 Changjuk Wind Power Co., Ltd. Electricity sales 754 863 788 KNH Solar Co., Ltd. Electricity sales 17 17 17 S-Power Service 7,278 5,994 12,852 Busan Solar Co., Ltd. Electricity sales 16 8 — Green Biomass Co., Ltd. Electricity sales 51 2 — SPC Power Corporation Dividend income 1,433 8,346 5,562 Gemeng International Energy Co., Ltd. Dividend income 37,163 16,476 13,365 PT. Cirebon Electric Power Dividend income — — 550 Dolphin Property Limited Dividend income — 35 — PT. Bayan Resources TBK Service 164 160 717 Nepal Water & Energy Development Company Private Limited Service — 375 900 Pioneer Gas Power Limited Service 274 164 62 Xe-Pian Xe-Namnoy Service 584 773 661 PT. Mutiara Jawa Service — — 47 <Joint ventures> Daegu Green Power Co., Ltd. Electricity sales — 768 1,131 KEPCO SPC Power Corporation Service 29,572 10,344 45,005 Daejung Offshore Wind Power Co., Ltd. Electricity sales 1 1 1 KAPES, Inc. Commission 1,315 1,176 1,420 Dangjin Eco Power Co., Ltd. Technical fee 334 1,787 670 Honam Wind Power Co., Ltd. Electricity sales 65 169 552 Seokmun Energy Co., Ltd. Service 2,395 1,627 1,765 Incheon New Power Co., Ltd. Construction revenue 388 524 539 Chun-cheon Energy Co., Ltd. Electricity sales 2,201 3,079 4,855 Yeonggwangbaeksu Wind Power Co., Ltd. Electricity sales 927 1,591 1,654 KW Nuclear Components Co., Ltd. Service 1,948 3,327 644 KEPCO-Uhde Inc. Service — 6 34 GS Donghae Electric Power Co., Ltd. Electricity sales 5,614 12,994 11,204 Busan Shinho Solar Power Co., Ltd. Electricity sales 24 210 87 Datang Chifeng Renewable Power Co., Ltd. Interest income 9,702 8,216 500 Rabigh Electricity Company Dividend income 565 699 19,179 Rabigh Operation & Maintenance Company Limited Dividend income 1,780 2,395 2,784 Datang Chaoyang Renewable Power Co., Ltd. Dividend income ￦ — — 839 Shuweihat Asia Power Investment B.V. Dividend income — 2,957 1,707 Shuweihat Asia Operation & Maintenance Company Electricity sales 1,006 1,179 1,319 ASM-BG Service — 322 1,062 Jamaica Public Service Company Limited Service 3,077 1,905 — KV Holdings, Inc. Dividend income — 302 — Datang KEPCO Chaoyang Renewable Co., Ltd. Dividend income — 440 — Amman Asia Electric Power Company Service 48,968 21,915 14,205 Kelar S.A Service 6,229 1,702 570 Nghi Son 2 Power Ltd. Electricity sales — — 2,693 Barakah One Company Electricity sales — 25,244 7,059 Nawah Energy Company Service — — 34,421 <Others> Yeongwol Energy Station Co., Ltd. Service 814 858 830 DS POWER Co., Ltd. Service 106,183 35,133 5,819 Korea Development Bank Electricity sales 4,039 3,102 3,239 Interest income 2,402 3,164 1,685 <Purchase and Others> Purchase and others Company name Transaction type 2015 2016 2017 In millions of won <Associates> Dongducheon Dream Power Co., Ltd. Electricity purchase ￦ 1,003,346 946,463 813,440 Korea Gas Corporation Purchase of power generation fuel 4,598,763 3,633,198 3,245,519 Daegu Photovoltaic Co., Ltd. REC purchase 3,978 3,243 3,646 Korea Power Engineering Service Co., Ltd. Service 3,241 723 1,292 KS Solar Co., Ltd. REC purchase 6,211 4,080 900 Heang Bok Do Si Photovoltaic Power Co., Ltd. Rental fee and others 479 410 570 Korea Electric Power Industrial Development Co., Ltd. Electricity metering service fee 273,057 250,057 289,293 Noeul Green Energy Co., Ltd. Service — — 15,862 Samcheok Eco Materials Co., Ltd. Electricity purchase — — 14 YTN Co., Ltd. Advertisement fee 440 554 731 Busan Green Energy Co., Ltd. Service — — 12,189 Korea Electric Vehicle Charging Service Service — — 1,093 Ulleungdo Natural Energy Co., Ltd. Electricity purchase — 60 119 Tamra Offshore Wind Power Co., Ltd. Electricity purchase — — 2,105 Cheongna Energy Co., Ltd. Service — 73 59 Gangwon Wind Power Co., Ltd. Electricity purchase 21,946 22,780 25,968 Hyundai Green Power Co., Ltd. Electricity purchase 486,443 469,547 458,378 Korea Power Exchange Trading Fees 79,283 91,433 207,855 Hyundai Energy Co., Ltd. Electricity purchase 1,684 1,313 87,607 Taebaek Wind Power Co., Ltd. REC purchase 6,626 5,741 6,534 Pyeongchang Wind Power Co., Ltd. Service — 1,594 4,033 Daeryun Power Co., Ltd. Electricity purchase 274,379 244,023 146,189 Changjuk Wind Power Co., Ltd. Electricity purchase 6,472 5,786 6,981 KNH Solar Co., Ltd. Electricity purchase ￦ 4,598 4,006 3,947 S-Power Electricity purchase 614,658 437,206 457,329 Busan Solar Co., Ltd. Electricity purchase 4,055 1,079 — Green Biomass Co., Ltd. Woodchip purchase 3,782 2,232 1,345 Nepal Water & Energy Development Company Private Limited Service — — 72 <Joint ventures> Daegu Green Power Co., Ltd. Electricity purchase 318,221 263,797 252,024 KAPES, Inc. Service 47,130 140,555 164,165 Honam Wind Power Co., Ltd. Electricity purchase 5,944 6,776 5,962 Seokmun Energy Co., Ltd. REC purchase — — 21,674 Chun-cheon Energy Co., Ltd. REC purchase — — 194,136 Yeonggwangbaeksu Wind Power Co., Ltd. Electricity purchase 4,974 11,208 11,124 GS Donghae Electric Power Co., Ltd. Electricity purchase — 903 351,367 Busan Shinho Solar Power Co., Ltd. REC purchase 7,565 6,770 7,984 Global Trade Of Power System Co., Ltd. Service 192 882 414 Expressway Solar-light Power Generation Co., Ltd. Electricity purchase 3,451 2,942 2,941 Jamaica Public Service Company Limited Service 106 127 154 Amman Asia Electric Power Company Service 125 — — Barakah One Company Service — — 2,631 <Others> Yeongwol Energy Station Co., Ltd. REC purchase 16,408 14,875 14,256 Korea Development Bank Interest expense 21,719 8,231 4,573 Dividend paid 96,087 654,829 418,407
Receivables and payables arising from related party transactions	Receivables Payables Company name Type 2016 2017 2016 2017 In millions of won <Associates> Dongducheon Dream Power Co., Ltd. Trade receivables ￦ 1,073 2,230 — — Non-trade — 655 — — Trade payables — — 93,493 77,817 Korea Gas Corporation Trade receivables 8,739 9,833 — — Non-trade 78 339 — — Trade payables — — 399,563 524,881 Non-trade — — 9,090 569 Daegu Photovoltaic Co., Ltd. Trade payables — — 56 71 Jeongam Wind Power Co., Ltd. Non-trade — — 4 4 KS Solar Co., Ltd. Trade receivables 2 — — — Trade payables — — 53 — Korea Electric Power Industrial Development Co., Ltd. Trade receivables 362 333 — — Non-trade 47 42 — — Non-trade — — 18,628 18,006 Goseong Green Energy Co., Ltd. Non-trade — 19 — — Non-trade — — 3,900 7,140 Gangneung Eco Power Co., Ltd. Trade receivables ￦ 1 1 — — Non-trade 2,137 4,747 — — Shin Pyeongtaek Power Co., Ltd. Non-trade 215 210 — — Non-trade — — — 52 Naepo Green Energy Co., Ltd. Trade receivables 14 17 — — Noeul Green Energy Co., Ltd. Trade receivables 18 3 — — Non-trade — — — 2,041 Samcheok Eco Materials Co., Ltd. Trade receivables 21 20 — — YTN Co., Ltd. Trade receivables 165 98 — — Non-trade — — 132 209 Busan Green Energy Co., Ltd. Trade receivables 9 7 — — Non-trade — 1,691 — — Korea Electric Vehicle Charging Service Trade receivables 12 23 — — Trade payables — — — 45 Ulleungdo Natural Energy Co., Ltd. Non-trade 111 — — — Cheongna Energy Co., Ltd. Trade receivables 165 182 — — Non-trade — — 82 1 Gangwon Wind Power Co., Ltd. Trade receivables 8 6 — — Trade payables — — 2,031 3,033 Hyundai Green Power Co., Ltd. Trade receivables 569 946 — — Trade payables — — 31,507 32,589 Korea Power Exchange Trade receivables 1,066 463 — — Non-trade 53 128 — — Non-trade — — 1,235 1,142 Hyundai Energy Co., Ltd. Trade receivables 72 49 — — Non-trade 68,798 6,598 — — Trade payables — — 86 223 Non-trade — — — 13,796 Ecollite Co., Ltd. Non-trade 210 210 — — Taebaek Wind Power Co., Ltd. Trade receivables — 116 — — Non-trade 112 — — — Trade payables — — 386 533 Non-trade — — 304 121 Pyeongchang Wind Power Co., Ltd. Trade receivables 4 3 — — Non-trade — — 255 163 Daeryun Power Co., Ltd. Trade receivables 140 162 — — Trade payables — — 21,646 15,706 Changjuk Wind Power Co., Ltd. Trade receivables 100 101 — — Trade payables — — 358 515 Non-trade — — 334 546 KNH Solar Co., Ltd. Trade receivables 1 1 — — Non-trade — — 204 193 S-Power Trade receivables 142 117 — — Non-trade 393 5,183 — — Trade payables — — 51,844 25,061 Green Biomass Co., Ltd. Non-trade ￦ — — 113 85 SPC Power Corporation Non-trade — 76 — — Nepal Water & Energy Development Company Private Limited Non-trade 889 227 — — Pioneer Gas Power Limited Non-trade 82 — — — Xe-Pian Xe-Namnoy Non-trade 58 53 — — <Joint ventures> Daegu Green Power Co., Ltd. Trade receivables 52 98 — — Non-trade 1 10 — — Trade payables — — 27,400 25,257 KEPCO SPC Power Corporation Non-trade 2,349 — — — KAPES, Inc. Non-trade 235 — — — Trade payables — — — 55 Non-trade — — 11,992 — Dangjin Eco Power Co., Ltd. Non-trade 833 1,211 — — Non-trade — — — 41 Honam Wind Power Co., Ltd. Trade payables — — 424 381 Non-trade — — 3,082 3,013 Seokmun Energy Co., Ltd. Trade receivables 114 93 — — Non-trade 160 276 — — Non-trade — — — 3,052 Incheon New Power Co., Ltd. Trade receivables 128 128 — — Chun-cheon Energy Co., Ltd. Trade receivables — 129 — — Non-trade 255 252 — — Trade payables — — — 29,676 Yeonggwangbaeksu Wind Power Co., Ltd. Trade receivables 6 7 — — Non-trade 145 144 — — Trade payables — — 761 619 Non-trade — — 1,362 1,300 KW Nuclear Components Co., Ltd. Trade receivables — 4 — — KEPCO-Uhde Inc. Non-trade — — 4 4 GS Donghae Electric Power Co., Ltd. Trade receivables 775 450 — — Non-trade 1,497 1,892 — — Trade payables — — — 73,570 Non-trade — — 993 — Busan Shinho Solar Power Co., Ltd. Trade receivables 3 2 — — Trade payables — — 129 159 Non-trade — — 670 811 Datang Chifeng Renewable Power Co., Ltd. Non-trade 210 82 — — Rabigh Operation & Maintenance Company Limited Trade receivables 2,275 — — — Non-trade — 869 — — ASM-BG Non-trade 64 37 — — Jamaica Public Service Company Limited Trade receivables 615 — — — Amman Asia Electric Power Company Trade receivables 2,509 2,675 — — Nawah Energy Company Trade receivables — 10,419 — — <Others> Yeongwol Energy Station Co., Ltd. Trade receivables 7,064 7,068 — — Trade payables — — 229 — DS POWER Co., Ltd. Trade receivables 1,775 340 — — Korea Development Bank Accrued interest income 672 204 — — Non-trade 217,481 501,029 — — Non-trade — — 408 200 Derivatives 25,306 569 3,278 22,398
Loans and others arising from related party transactions	Type Company name Beginning Loans Collection Others Ending balance In millions of won Associates KNOC Nigerian East Oil Co., Ltd., KNOC Nigerian West Oil Co., Ltd. ￦ 29,282 169 — (3,110 ) 26,341 (Allowance for doubtful accounts) (18,191 ) — — 1,640 (16,551 ) Associates PT. Cirebon Electric Power 26,733 2,199 (7,876 ) (5,620 ) 15,436 Associates Xe-Pian Xe-Namnoy 1,413 — — — 1,413 Associates PT Wampu Electric Power 14,022 905 — (1,639 ) 13,288 Associates Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) 9,396 — — — 9,396 Associates Hyundai Energy Co., Ltd. 2,465 — — — 2,465 (Allowance for doubtful accounts) — — — (2,465 ) (2,465 ) Joint ventures KEPCO SPC Power Corporation 27,795 — (7,803 ) (2,743 ) 17,249 Joint ventures Datang Chifeng Renewable Power Co., Ltd. 16,344 — (7,647 ) (1,452 ) 7,245 Joint ventures Rabigh Electricity Company 2,641 — (2,496 ) (145 ) — Joint ventures KODE NOVUS II LLC 4,532 — — (514 ) 4,018 (Allowance for doubtful accounts) (4,532 ) — — 514 (4,018 ) Joint ventures Kelar S.A — 54,631 (3,568 ) (4,443 ) 46,620 Joint ventures Daehan Wind Power PSC 683 640 — (112 ) 1,211 Joint ventures Chester Solar IV SpA — 4,802 — (195 ) 4,607 ￦ 112,583 63,346 (29,390 ) (20,284 ) 126,255
Borrowings arising from related party transactions	Related parties Type Beginning balance Borrowings Repayment Others Ending balance In millions of won Korea Development Facility ￦ 207,993 27,324 (141,434 ) — 93,883 Bank Others 5,663 — (754 ) — 4,909 Operating funds 37,000 49,000 (25,000 ) — 61,000 Syndicated Loan 6,075 11,855 — (1,629 ) 16,301
Guarantees provided to associates or joint ventures	Primary guarantor Principal obligor Type of guarantees Credit limit Guarantee In millions of won and thousands of foreign currencies Korea Electric Power Corporation Shuweihat Asia Operation & Maintenance Company Performance guarantees USD 11,000 SAPCO Korea Electric Power Corporation KNOC Nigerian East Oil Co., Ltd. and KNOC Nigerian West Oil Co., Ltd. Performance guarantees USD 34,650 Korea National Oil Corporation (Nigerian government) Korea Electric Power Corporation Rabigh Operation & Maintenance Company Limited Performance guarantees and others USD 1,387 RABEC Korea Electric Power Corporation Nghi Son 2 Power Ltd. Bidding guarantees USD 10,000 SMBC Ho Chi Minh Korea Electric Power Corporation Barakah One Company Debt guarantees USD 900,000 Export-Import Bank of Korea and others Performance guarantees and others USD 3,404,275 Korea Western Power Co., Ltd. Cheongna Energy Co., Ltd. Collateralized money invested KRW 27,211 KEB Hana Bank and others Guarantees for supplemental funding and others (*1) — Korea Western Power Co., Ltd. Xe-Pian Xe-Namnoy Payment guarantees for business reserve USD 2,500 Krung Thai Bank Collateralized money invested USD 62,253 Krung Thai Bank Impounding bonus guarantees USD 5,000 SK E&C Korea Western Power Co., Ltd. Rabigh Operation & Maintenance Company Limited Performance guarantees and others SAR 5,600 Saudi Arabia British Bank Korea Western Power Co., Ltd. Daegu Photovoltaic Co., Ltd. Collateralized money invested KRW 1,230 Korea Development Bank Korea Western Power Co., Ltd. Dongducheon Dream Power Co., Ltd. Collateralized money invested KRW 53,233 Kookmin Bank and others Korea Western Power Co., Ltd. PT. Mutiara Jawa Collateralized money invested USD 2,610 Woori Bank Korea Western Power Co., Ltd. Heang Bok Do Si Photovoltaic Power Co., Ltd. Collateralized money invested KRW 194 Nonghyup Bank Korea Western Power Co., Ltd. Shin Pyeongtaek Power Co., Ltd. Collateralized money invested KRW 43,920 Kookmin Bank Korea East-West Power Co., Ltd. Busan Shinho Solar Power Co., Ltd. Collateralized money invested KRW 2,100 Korea Development Bank and others Korea East-West Power Co., Ltd. Seokmun Energy Co., Ltd. Collateralized money invested KRW 15,370 Kookmin Bank and others Korea East-West Power Co., Ltd. Chun-cheon Energy Co., Ltd. Collateralized money invested KRW 52,700 Kookmin Bank and others Guarantees for supplemental funding(*1) KRW 60,270 Kookmin Bank and others Korea East-West Power Co., Ltd. Honam Wind Power Co., Ltd. Collateralized money invested KRW 3,480 Shinhan Bank and others Korea East-West Power Co., Ltd. GS Donghae Electric Power Co., Ltd. Collateralized money invested KRW 204,000 Korea Development Bank and others Korea East-West Power Co., Ltd. Yeonggwangbaeksu Wind Power Co., Ltd. Collateralized money invested KRW 3,000 Kookmin Bank and others Korea East-West Power Co., Ltd. Yeonggwang Wind Power Co., Ltd. Collateralized money invested KRW 15,375 KEB Hana Bank and others Korea East-West Power Co., Ltd. PT. Tanjung Power Indonesia Debt guarantees USD 46,983 The Bank of Tokyo-Mitsubishi and others Other guarantees USD 3,150 PT Adaro Indonesia EWP Barbados 1 SRL South Jamaica Power Company Limited Performance guarantees USD 14,400 Societe Generale Guarantees for supplemental funding and others(*1, 3) USD 60,000 JCSD Trustee Services Limited and others Korea Southern Power Co., Ltd. KNH Solar Co., Ltd. Collateralized money invested KRW 1,296 Shinhan Bank and Kyobo Life Insurance Co., Ltd. Performance guarantees and guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Daeryun Power Co., Ltd. Collateralized money invested KRW 25,477 Korea Development Bank and others Guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Changjuk Wind Power Co., Ltd. Collateralized money invested KRW 3,801 Shinhan Bank Guarantees for supplemental funding(*1) — Korea Southern Power Co., Ltd. Daegu Green Power Co., Ltd. Collateralized money invested KRW 46,226 Shinhan Bank Korea Southern Power Co., Ltd. Kelar S.A Performance guarantees USD 63,707 KEB Hana Bank, SMBC, Mizuho Bank and others Korea Southern Power Co., Ltd. DS POWER Co., Ltd. Collateralized money invested KRW 2,900 Korea Development Bank and others Guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Pyeongchang Wind Power Co., Ltd. Collateralized money invested KRW 3,875 Woori Bank and Shinhan Bank Performance guarantees and guarantees for supplemental funding and others(*1) — Korea Southern Power Co., Ltd. Taebaek Wind Power Co., Ltd. Guarantees for supplemental funding and others(*1) — Shinhan Bank Korea Southern Power Co., Ltd. Jeongam Wind Power Co., Ltd Collateralized money invested Guarantees for supplemental funding and others (*1) KRW 5,580 — SK Securities Co., Ltd. Korea Southern Power Co., Ltd. Naepo Green Energy Co., Ltd. KRW 29,200 Hana Financial Investment Co., Ltd. and others Guarantees for supplemental funding and others (*1) — KEPCO Engineering & Construction Company, Inc. DS POWER Co., Ltd. Collateralized money invested KRW 15,000 Korea Development Bank and others Korea Midland Power Co., Ltd. Hyundai Green Power Co., Ltd. Collateralized money invested KRW 87,003 Korea Development Bank and others Guarantees for supplemental funding and others (*1) — Korea Midland Power Co., Ltd. PT. Cirebon Electric Power Debt guarantees USD 11,550 Mizuho Bank Korea Midland Power Co., Ltd. PT Wampu Electric Power Debt guarantees USD 5,068 SMBC Korea Midland Power Co., Ltd. Gangwon Wind Power Co., Ltd. Collateralized money invested KRW 7,409 IBK and others Korea Midland Power Co., Ltd. YaksuESS Co., Ltd Collateralized money invested KRW 210 Hanwha Life Insurance Co., Ltd. Guarantees for supplemental funding and others (*1) — Korea South-East Power Co., Ltd. Hyundai Energy Co., Ltd. Collateralized money invested KRW 47,067 Korea Development Bank and others Performance guarantees and guarantees for supplemental funding and others (*1) KRW 78,600 Korea South-East Power Co., Ltd. RES Technology AD Collateralized money invested KRW 15,595 UniCredit Bulbank and others Korea South-East Power Co., Ltd. ASM-BG Collateralized money invested KRW 16,101 UniCredit Bulbank and others Korea South-East Power Co., Ltd. Express Solar-light Power Generation Co., Ltd. Guarantees for supplemental funding (*1, 2) KRW 2,500 Woori Bank Korea South-East Power Co., Ltd. S-Power Collateralized money invested KRW 132,300 Korea Development Bank and others KOSEP USA, INC. KODE NOVUS II LLC Guarantees for supplemental funding and others (*1) — Korea Development Bank KOSEP USA, INC. KODE NOVUS I LLC Guarantees for supplemental funding and others (*1) — Export-Import Bank of Korea and others Korea Hydro & Nuclear Power Co., Ltd. Yeongwol Energy Station Co., Ltd. Collateralized money invested KRW 1,400 Meritz Fire & Marine Insurance Co., Ltd. Korea Hydro & Nuclear Power Co., Ltd. Noeul Green Energy Co., Ltd., Collateralized money invested KRW 1,740 KEB Hana Bank and others Korea Hydro & Nuclear Power Co., Ltd. Busan Green Energy Co., Ltd. Collateralized money invested KRW 5,243 Shinhan Bank and others KEPCO Plant Service & Engineering Co., Ltd. Incheon New Power Co., Ltd. Collateralized money invested KRW 8,160 Shinhan Bank Guarantees for supplemental funding and others (*1) — (*1) The Company guarantees to provide supplemental funding for business with respect to excessive business expenses or insufficient repayment of borrowings. (*2) The Company has granted the right to Hana Financial Investment Co., Ltd., as an agent for the creditors to Express Solar-light Power Generation Co., Ltd. (“ESPG”), to the effect that in the event of acceleration of ESPG’s payment obligations under certain borrowings to such creditors, Hana Financial may demand the Company to dispose of shares in ESPG held by the Company and apply the resulting proceeds to repayment of ESPG’s obligations. (*3) This includes a guarantee for the shareholder’s capital payment in connection with the business of 190MW gas complex thermal power plant in Jamaica. EWP (Barbados) 1 SRL’s capital contribution amount is USD 6,400 thousand and the total amount of guarantees is USD 27,000 thousand which consists of USD 12,000 thousand of EWP (Barbados) 1 SRL’s contribution obligation and USD 15,000 thousand of SJEH’s portion (50%) of contribution obligation.
Derivatives transactions with related parties	(i) Currency Swap In millions of won and thousands of U.S. dollars Counterparty Contract Contract Amount Contract interest rate per annum Contract exchange rate Pay Receive Pay (%) Receive (%) Korea Development Bank 2016~2019 ￦ 105,260 USD 100,000 2.48 % 2.38 % ￦ 1,052.60 2015~2025 111,190 USD 100,000 2.62 % 3.25 % 1,111.90 2017~2027 111,610 USD 100,000 2.31 % 3.13 % 1,116.10 2017~2020 114,580 USD 100,000 1.75 % 2.38 % 1,145.80 2016~2021 121,000 USD 100,000 2.15 % 2.50 % 1,210.00 2017~2022 113,300 USD 100,000 1.94 % 2.63 % 1,133.00 (ii) Currency forward In millions of won and thousands of foreign currencies Counterparty Contract Date Maturity date Contract amounts Contract exchange Pay Receive Korea Development Bank 2017.12.27 2021.07.12 ￦ 104,849 USD 100,000 ￦ 1,048.49 2017.12.14 2018.01.10 11,950 USD 11,000 1,086.35 2017.12.20 2018.01.16 15,130 USD 14,000 1,080.70 2017.12.28 2018.01.31 11,782 USD 11,000 1,071.10
Salaries and other compensations to the key members of management of the Company	Salaries and other compensations to the key members of management of the Company for the years ended December 31, 2015, 2016 and 2017 are as follows: Type 2015 2016 2017 In millions of won Salaries ￦ 1,271 1,463 1,271 Employee benefits 59 33 54 ￦ 1,330 1,496 1,325

Non-Cash Transactions (Tables)

Non-Cash Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Non-Cash Transactions [Abstract]
Significant non-cash activities	Significant non-cash Transactions 2015 2016 2017 In millions of won Transfer from construction-in-progress ￦ 10,491,054 19,971,599 13,676,233 Recognition of asset retirement cost and related provision for decommissioning costs 699,673 470,941 2,494,802 Transfer from provision for disposal of spent nuclear fuel to accrued expenses 491,755 283,675 342,861

Commitments for Expenditure (Ta

Commitments for Expenditure (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments for Expenditure [Abstract]
Commitments for acquisition of property, plant and equipment	2016 2017 Contracts Amounts Balance Amounts Balance In millions of won Purchase of switch (25.8kV Eco) 11,395 ￦ 40,226 28,072 40,226 — Purchase of switch (25.8kV Eco) 12,450 — — 50,526 35,494 Purchase of cable (PVC,1C,2000SQ) 153,000M and others (Shin-Bupyung-Youngseo) 50,256 50,256 50,256 42,857 Purchase of cable (PVC, 1C, 2500SQ) 103,374M and others (Bukdangjin-Shintangjung) 42,500 42,500 42,500 29,987 Purchase of GIS (362KV 6300A 63KA) 23CB – YoungseoS/S — — 34,500 34,500 Purchase of GIS (362KV 6300A 63KA) 26CB – Shin-gosungS/S 36,950 19,897 36,950 — Purchase of GIS (362KV 6300A 63KA) 26CB – HwasungS/S — — 40,000 29,231 Purchase of GIS (362KV 6300A 63KA) 27CB – KwangyangS/S 37,476 27,760 37,476 18,044 Purchase of GIS (362KV 6300A 63KA) and 1 other 18CB – BukbusanS/S 34,000 20,766 34,000 — Purchase of GIS (800KV 8000A 50KA) 10CB – Shin-JungbuS/S 63,730 63,730 63,730 44,955 Purchase of transformer (765/345/23kV 666.7MVA, 2TANK) 6 units – Shin-JungbuS/S 37,500 37,500 37,500 37,500 Purchase of cable (TR CNCE-W/AL,1C,400SQ) 71,986 50,593 71,986 — Purchase of Concrete Poles (10M, 350KGF) 104,755 and 6 others 129,175 105,905 129,175 — Purchase of cable (TR CNCE-W/AL,1C,400SQ) — — 78,076 76,762 Purchase of Concrete Poles (10M, 350KGF) 121,900 and 6 others — — 133,387 112,981 Advanced E-Type — — 65,408 64,592 Purchase of Ground Switch (44-D-A125, — — 56,482 55,990 Construction of Shin-Kori units (#3,4) 6,856,150 — 7,363,514 93,637 Construction of Shin-Kori units (#5,6) 8,625,387 7,286,503 8,625,387 6,757,146 Construction of Shin-Hanwool units (#1,2) 7,982,342 1,157,700 7,982,342 1,015,813 Construction of Shin-Hanwool units (#3,4) 8,261,818 8,170,896 8,261,818 8,097,056 Construction of Yeosu thermal power units (#1) 174,291 1,139 174,291 — Other 27 contracts 430,204 222,555 262,400 114,041 Purchase of main machine for construction of Seoul Combined units (#1,2) 360,500 300,663 361,203 99,031 Construction of Seoul Combined units (#1,2) 225,205 129,589 227,685 60,568 Electricity construction of Shin-Boryeong units (#1,2) 354,740 26,878 379,115 — Purchase of smoke eliminating machine for construction of Shin-Boryeong units (#1,2) 121,093 2,023 169,544 36,417 Purchase of coal handling machine for construction of Shin-Boryeong units (#1,2) ￦ 146,353 3,543 146,353 — Service of designing Shin-Boryeong units (#1,2) 126,038 24,333 127,810 16,371 Purchase of main machine for construction of Shin-Boryeong units (#1,2) 851,132 10,746 866,065 4,981 Construction of Shin-Boryeong units (#1,2) 288,438 17,828 316,190 23,100 Purchase of furnace for construction of Shin-Seocheon thermal power plant — — 302,030 222,555 Purchase of turbine generator for construction of Shin-Seocheon thermal power plant — — 104,402 83,522 Electricity construction of Shin-Seocheon thermal power plant — — 200,453 196,993 Purchase of main machine for Jeju LNG combined — — 166,287 15,409 Purchase of coal handling machine for construction of Taean (#9,10) and IGCC units (conditional contract for installation) 192,945 38,218 193,375 5,129 Purchase of furnace for construction of Taean units (#9,10) 584,148 46,059 566,945 33,817 Service of designing Taean units (#9,10) 109,700 18,981 111,322 13,671 Purchase of desulfurization machine for construction of Taean units (#9,10) 92,086 1,017 — — Purchase of turbine generator for construction of Taean units (#9,10) 228,794 6,788 205,267 550 Purchase of combined generating machine for construction of Taean IGCC units 208,972 2,102 190,923 — Purchase of oxygen plant for construction of Taean IGCC units 98,979 221 94,564 199 Service of designing Taean IGCC plant units 44,802 3,342 44,802 2,669 Purchase of gasification plant for construction of Taean IGCC units 457,991 — 456,037 — Construction of Samcheok units (#1,2) 457,943 15,851 488,347 — Purchase of furnace for construction of Samcheok units (#1,2) 1,091,303 51,594 1,082,641 5,963 Purchase of coal handling machine for construction of Samcheok units (#1,2) 303,273 155 304,924 52,362 Service of designing Samcheok units (#1,2) 114,047 36,510 114,047 4,745 Purchase of main equipment 152,286 39,248 168,076 — Landscaping construction and other — — 63,110 — Construction of yard for Andong natural gas power plant 41,961 2,600 41,961 — Purchase of turbine main equipment for Samcheok units (#1,2) — — 215,333 874 Service of designing Dangjin units (#9,10) 122,426 6,125 122,426 —
Commitments for inventory purchase	Contract periods for ore concentrates, conversion, enrichment and design and fabrication are as follows: Type Periods Contracted amounts Concentrate 2017 ~ 2030 39,662 Ton U3O8 Transformed 2017 ~ 2030 22,934 Ton U Enrichment 2017 ~ 2029 25,530 Ton SWU Molded 2017 ~ 2022 2,004 Ton U

Contingencies and Commitments (

Contingencies and Commitments (Tables)	12 Months Ended
	Dec. 31, 2017
Contingencies and Commitments [Abstract]
Ongoing litigations related with contingent liabilities and contingent assets	2016 2017 Number Claim Number Claim In millions of won As the defendant 675 ￦ 636,433 565 ￦ 477,719 As the plaintiff 193 489,605 185 690,934
Credit lines provided by financial institutions	Credit lines provided by financial institutions as of December 31, 2017 are as follows: Commitments Financial institutions Currency Limited amount Exercised amount In millions of won and thousands of foreign Commitments on bank-overdraft Nonghyup Bank and others KRW 1,555,000 68,859 Commitments on bank-daylight overdraft Nonghyup Bank KRW 280,000 — Limit amount available for CP Shinhan Bank and others KRW 1,100,000 — Limit amount available for card KEB Hana Bank and others KRW 46,733 2,775 Banco de Oro PHP 5,000 5,000 Loan limit Kookmin Bank and others KRW 895,500 425,411 BNP Paribas and others USD 1,910,700 20,000 Certification of payment on L/C Woori Bank and others USD 1,029,604 233,166 Certification of performance guarantee on contract KEB Hana Bank EUR 1,958 1,958 KEB Hana Bank and others INR 230,515 230,515 Korea Development Bank and others JPY 620,000 620,000 Seoul Guarantee Insurance and others KRW 104,248 104,248 Bank of Kathmandu NPR 32,633 32,633 KEB Hana Bank SAR 102,186 87,991 Standard Chartered and others USD 753,652 696,806 KEB Hana Bank CAD 168 168 Certification of bidding SMBC and others USD 60,000 10,230 ABSA and others ZAR 55,730 55,730 Advance payment bond, Warranty bond, Retention bond and others KEB Hana Bank INR 157,830 157,830 Export-Import Bank of Korea and others USD 3,850,534 753,025 Others Nonghyup Bank and others KRW 451,521 15,037 KEB Hana Bank and others USD 1,063,670 758,536 Inclusive credit Shinhan Bank INR 47,489 47,489 KEB Hana Bank KRW 258,000 117,398 Shinhan Bank and others USD 32,125 16,155 Trade finance BNP Paribas and others USD 800,000 —
Blank check and assets provided as collaterals or pledges to financial institutions by the Company	As of December 31, 2017, the blank check and assets provided as collaterals or pledges to financial institutions by the Company are follows: Guarantor Guarantee Type of guarantee Currency Amount Description In millions of won and thousands of foreign currencies Korea East-West Power Co., Ltd. Korea Development Bank and others Shareholdings of Gyeongju Wind Power Co., Ltd. KRW 15,958 Collateral for borrowings Korea Midland Power Co.,Ltd. IBK and others Shareholdings of Commerce and Industry Energy Co., Ltd. KRW 13,605 Collateral for borrowings Korea Southern Power Co., Ltd. Shinhan Bank and others Shareholdings of KOSPO Youngnam Power Co., Ltd. KRW 40,000 Collateral for borrowings Korea South-East Power Co., Ltd. International Finance Corporation and others Shareholdings of Mira Power Limited KRW 44,192 Collateral for borrowings Korea Hydro & Nuclear Power Co., Ltd. Korea Development Bank and others Shareholdings of Gyeonggi Green Energy Co., Ltd. KRW 47,000 Collateral for borrowings Gyeonggi Green Energy Co., Ltd. Korea Development Bank and others Factory estate and others KRW 327,080 Collateral for borrowings (*) Commerce and Industry Energy Co., Ltd. IBK and others Land, buildings, structures and machinery and others Cash and cash equivalents KRW KRW 110,500 11,642 Collateral for borrowings Gyeongju Wind Power Co., Ltd. SK Securities Co., Ltd. and others Property, plant and equipment and others KRW 97,980 Collateral for borrowings Existing or expected trade receivables KRW 4,800 Cash and cash equivalents KRW 8,769 KOSPO Youngnam Power Co., Ltd. Shinhan Bank and others Bank deposit and insurance claim KRW 396,120 Collateral for borrowings Qatrana Electric Power Company The Islamic Development Bank and others Finance Lease receivable and property, plant and equipment and others JOD 188,580 Collateral for borrowings KST Electric Power Company Scotiabank Inverlat, S.A Finance Lease receivable and others USD 289,026 Collateral for borrowings (*) The Company was provided with shares of Gyeonggi Green Energy Co., Ltd., one of its subsidiaries, from the investors as collateral related to long-term borrowings. Additionally, pledge for shares, pledge for transfer of rights of long-term borrowings, pledge for insurance claims and other pledges were established.

Subsequent Events (Tables)

Subsequent Events (Tables)	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent to December 31, 2017, Korea Hydro & Nuclear Power Co., Ltd., Korea South-East Power Co., Ltd., Korea Midland Power Co., Ltd. and Korea Southern Power Co., Ltd. issued additional corporate bond, asset backed short-term bond, non-guaranteed Company Name Type Issue date Maturity Interest rate (%) Amounts In millions of won and thousands of foreign currencies Korea Hydro & Nuclear Power Co., Ltd. #48-1 2018.03.13 2021.03.13 2.40 ￦ 160,000 #48-2 2018.03.13 2023.03.13 2.70 20,000 #48-3 2018.03.13 2028.03.13 2.86 30,000 #48-4 2018.03.13 2048.03.13 2.94 90,000 Global bond 9 2018.03.13 2028.03.13 3.35 HKD 1,650,000 Korea South-East Power Co., Ltd Asset backed short-term bond 2018.01.24 2018.04.10 1.79 190,000 Korea Midland Power Co., Ltd #41-1 non-guaranteed corporate bond 2018.02.20 2023.02.20 2.72 60,000 #41-2 non-guaranteed corporate bond 2018.02.20 2028.02.20 2.92 130,000 Korea Southern Power Co., Ltd #43-1 non-guaranteed bond 2018.01.11 2021.01.11 2.32 120,000 #43-2 non-guaranteed bond 2018.01.11 2023.01.11 2.57 20,000 #43-3 non-guaranteed bond 2018.01.11 2028.01.11 2.76 60,000 Non-guaranteed foreign currency bond (Global bond 18) 2018.01.29 2021.01.29 3.00 USD 400,000

General Information (Details)

General Information (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reporting Entity (Description of the controlling company) [Abstract]
Name of reporting entity or other means of identification	Korea Electric Power Corporation and subsidiaries
Name of parent entity	Korea Electric Power Corporation
Entity Incorporation, Date of Incorporation	Incorporated on January 1, 1982 in accordance with the Korea Electric Power Corporation Act (the “KEPCO Act”)
Description of nature of entity's operations and principal activities	Engage in the generation, transmission and distribution of electricity and development of electric power resources. KEPCO also provides power plant construction services.
Country of incorporation	Republic of Korea.
Information of listing on stock market	KEPCO’s stock was listed on the Korea Stock Exchange on August 10, 1989 and KEPCO listed its Depository Receipts (DR) on the New York Stock Exchange on October 27, 1994.
Address of registered office of entity	KEPCO’s head office is located in Naju, Jeollanam-do.
Issued capital	₩ 3,209,820	₩ 3,209,820

Shareholders Information (Detai

Shareholders Information (Details) - shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of shareholders information [Line Items]
Number of shares	641,964,077	641,964,077	641,964,077
Percentage of ownership	100.00%
Government of the Republic of Korea [Member]
Disclosure of shareholders information [Line Items]
Number of shares	116,841,794
Percentage of ownership	18.20%
Korea Development Bank [Member]
Disclosure of shareholders information [Line Items]
Number of shares	211,235,264
Percentage of ownership	32.90%
Foreign investors [Member]
Disclosure of shareholders information [Line Items]
Number of shares	194,050,746
Percentage of ownership	30.23%
Other Shareholders [Member]
Disclosure of shareholders information [Line Items]
Number of shares	119,836,273
Percentage of ownership	18.67%

Explanation of initial applicat

Explanation of initial application of IFRS 9 (Details) ₩ in Millions	Dec. 31, 2017KRW (₩)
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	₩ 16,018,152
Amount based on IAS 39	16,018,152
Financial assets at FVTPL [Member] | FVTPL [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	111,512
Amount based on IAS 39	111,512
Loans and receivables [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IAS 39	15,203,663
Loans and receivables [Member] | Amortized cost [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	14,412,339
Loans and receivables [Member] | FVTPL [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	791,324
Available-for-sale financial assets [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IAS 39	699,833
Available-for-sale financial assets [Member] | FVOCI [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	476,941
Available-for-sale financial assets [Member] | FVTPL [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	222,892
Held-to-maturity investments [Member] | Amortized cost [Member]
Disclosure of Explanation of initial application of IFRS 9 [Line Items]
Amount based on IFRS 9	3,144
Amount based on IAS 39	₩ 3,144

Impairment Explanation of initi

Impairment Explanation of initial application of IFRS 9 (Details) ₩ in Millions	Dec. 31, 2017KRW (₩)
Disclosure of Impairment Explanation of initial application of IFRS 9 [Line Items]
Impairment Amount based on IAS 39	₩ 260,539
Impairment Amount based on IFRS 9	267,308
Impairment Amount Effect of initial application of IFRS 9	6,769
Trade and other receivables [Member]
Disclosure of Impairment Explanation of initial application of IFRS 9 [Line Items]
Impairment Amount based on IAS 39	251,591
Impairment Amount based on IFRS 9	258,360
Impairment Amount Effect of initial application of IFRS 9	6,769
Other financial assets [Member]
Disclosure of Impairment Explanation of initial application of IFRS 9 [Line Items]
Impairment Amount based on IAS 39	8,948
Impairment Amount based on IFRS 9	₩ 8,948

Significant Basis Of Preparatio

Significant Basis Of Preparation And Accounting Policies_Estimated economic useful lives for premises and equipment except for land (Details)	12 Months Ended
	Dec. 31, 2017
Buildings [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	8 ~ 40
Structures [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	8 ~ 50
Machinery [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	2 ~ 32
Vehicles [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	3 ~ 8
Loaded heavy water [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	30
Asset retirement costs [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	18, 30, 40, 60
Finance lease assets [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	6 ~ 32
Ships [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	9
Others [Member]
Disclosure of useful life of property plant and equipment [Line Items]
Useful lives (years)	4 ~ 15

Significant Basis Of Prepara115

Significant Basis Of Preparation And Accounting Policies_Estimated useful life for intangible assets (Details)	12 Months Ended
	Dec. 31, 2017
Usage rights for donated assets [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	10 ~ 20
Amortization methods	Straight line
Software [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	4, 5
Amortization methods	Straight line
Industrial rights [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	5, 10
Amortization methods	Straight line
Development expenses [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	5
Amortization methods	Straight line
Leasehold rights [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	10
Amortization methods	Straight line
Mining rights [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	-
Amortization methods	Unit of production
Other intangible assets [Member]
Disclosure of intangible assets with indefinite useful life [Line Items]
Useful lives (years)	3 ~ 50 or Indefinite
Amortization methods	Straight line

Operating segments (Details)

Operating segments (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [Line Items]
Total segment revenue	₩ 59,335,889	₩ 59,763,087	₩ 58,581,727
Revenue from external customers	59,335,889	59,763,087	58,581,727
Depreciation and amortisation	9,773,711	8,960,988	8,341,384
Interest income	206,143	241,778	241,585
Interest expense	1,789,552	1,752,868	2,015,684
Employee benefit expense	391,360	373,753	314,692
Loss on abandonment of property, plant and equipment	424,091	426,519	365,056
Increase in provisions, net	1,690,120	1,782,732	1,602,724
Operating profit (loss)	5,319,869	12,296,360	20,280,876
Finance income	1,530,618	791,543	1,182,988
Finance expense	(3,127,952)	(2,437,087)	(3,015,457)
Profit (loss) related to associates and joint ventures	(108,317)	(137,348)	207,379
Profit before income tax	3,614,218	10,513,468	18,655,786
Segment assets	181,788,915	177,837,042
Investments in associates and joint ventures	5,330,696	5,510,448
Acquisition of non-current assets	12,679,845	12,153,211
Segment liabilities	108,824,274	104,786,497
Operating segments [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	94,974,836	95,611,310	93,482,228
Intersegment revenue	35,638,947	35,848,223	34,900,501
Revenue from external customers	59,335,889	59,763,087	58,581,727
Depreciation and amortisation	9,833,297	9,006,486	8,380,371
Interest income	230,685	264,764	299,989
Interest expense	1,818,399	1,778,479	2,072,957
Employee benefit expense	421,827	400,072	338,725
Loss on abandonment of property, plant and equipment	424,091	426,519	365,056
Increase in provisions, net	2,076,867	1,785,741	1,596,934
Operating profit (loss)	5,152,814	12,543,173	20,242,883
Profit (loss) related to associates and joint ventures	(108,317)	(137,348)	207,379
Segment assets	220,561,693	216,061,727
Investments in associates and joint ventures	5,330,696	5,510,448
Acquisition of non-current assets	12,656,229	12,345,112
Segment liabilities	110,538,279	107,405,716
Operating segments [Member] | Transmission and distribution [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	59,486,766	59,862,284	58,164,394
Intersegment revenue	2,044,160	1,890,489	1,230,975
Revenue from external customers	57,442,606	57,971,795	56,933,419
Depreciation and amortisation	3,466,410	3,226,700	2,859,037
Interest income	49,987	80,882	132,809
Interest expense	737,971	844,200	1,092,594
Employee benefit expense	158,738	162,326	135,261
Loss on abandonment of property, plant and equipment	384,595	424,356	359,521
Increase in provisions, net	885,195	711,430	872,096
Operating profit (loss)	1,902,634	5,274,308	13,319,310
Profit (loss) related to associates and joint ventures	(105,166)	(128,402)	220,406
Segment assets	106,540,154	105,321,129
Investments in associates and joint ventures	3,366,309	4,121,462
Acquisition of non-current assets	6,606,512	6,345,004
Segment liabilities	50,757,798	49,854,420
Operating segments [Member] | Electric power generation (Nuclear) [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	9,415,752	11,168,579	10,642,352
Intersegment revenue	9,359,468	11,129,385	10,596,189
Revenue from external customers	56,284	39,194	46,163
Depreciation and amortisation	3,267,510	3,130,820	3,070,828
Interest income	21,034	33,111	24,612
Interest expense	487,503	474,590	532,490
Employee benefit expense	80,809	70,582	54,572
Increase in provisions, net	801,800	576,223	401,839
Operating profit (loss)	1,347,794	3,770,165	3,806,617
Profit (loss) related to associates and joint ventures	3,637	(1,082)	(595)
Segment assets	55,011,096	52,782,915
Investments in associates and joint ventures	11,843	15,384
Acquisition of non-current assets	2,083,967	1,945,610
Segment liabilities	29,252,816	27,366,938
Operating segments [Member] | Electric power generation (Non-nuclear) [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	22,795,816	21,394,223	21,469,345
Intersegment revenue	21,885,251	20,561,044	20,906,081
Revenue from external customers	910,565	833,179	563,264
Depreciation and amortisation	2,954,375	2,523,306	2,337,353
Interest income	18,860	24,171	22,171
Interest expense	486,176	359,607	319,647
Employee benefit expense	94,075	79,846	74,007
Loss on abandonment of property, plant and equipment	39,335	2,133	5,305
Increase in provisions, net	171,457	276,619	148,053
Operating profit (loss)	1,523,497	3,211,684	2,704,260
Profit (loss) related to associates and joint ventures	(6,718)	(8,342)	(10,686)
Segment assets	47,938,084	47,427,642
Investments in associates and joint ventures	1,904,224	1,320,203
Acquisition of non-current assets	3,250,524	3,508,313
Segment liabilities	26,337,295	26,205,049
Operating segments [Member] | Plant maintenance & engineering service [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	2,621,440	2,618,388	2,533,887
Intersegment revenue	2,211,716	2,190,207	2,016,699
Revenue from external customers	409,724	428,181	517,188
Depreciation and amortisation	109,001	98,843	85,662
Interest income	10,801	10,672	12,293
Interest expense	2,967	2,156	542
Employee benefit expense	87,344	86,268	74,542
Loss on abandonment of property, plant and equipment	161
Increase in provisions, net	219,382	221,301	174,912
Operating profit (loss)	265,593	210,680	332,531
Profit (loss) related to associates and joint ventures	(70)	478	(1,746)
Segment assets	3,273,959	3,106,909
Investments in associates and joint ventures	48,320	53,399
Acquisition of non-current assets	145,779	180,715
Segment liabilities	1,176,627	1,218,047
Operating segments [Member] | Others [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	655,062	567,836	672,250
Intersegment revenue	138,352	77,098	150,557
Revenue from external customers	516,710	490,738	521,693
Depreciation and amortisation	36,001	26,817	27,491
Interest income	130,003	115,928	108,104
Interest expense	103,782	97,926	127,684
Employee benefit expense	861	1,050	343
Loss on abandonment of property, plant and equipment		30	230
Increase in provisions, net	(967)	168	34
Operating profit (loss)	113,296	76,336	80,165
Segment assets	7,798,400	7,423,132
Acquisition of non-current assets	569,447	365,470
Segment liabilities	3,013,743	2,761,262
Material reconciling items [Member]
Disclosure of operating segments [Line Items]
Total segment revenue	(35,638,947)	(35,848,223)	(34,900,501)
Intersegment revenue	(35,638,947)	(35,848,223)	(34,900,501)
Depreciation and amortisation	(59,586)	(45,498)	(38,987)
Interest income	(24,542)	(22,986)	(58,404)
Interest expense	(28,847)	(25,611)	(57,273)
Employee benefit expense	(30,467)	(26,319)	(24,033)
Increase in provisions, net	(386,747)	(3,009)	5,790
Operating profit (loss)	167,055	(246,813)	₩ 37,993
Segment assets	(38,772,778)	(38,224,685)
Acquisition of non-current assets	23,616	(191,901)
Segment liabilities	(1,714,005)	(2,619,219)
Elimination of intersegment amounts [Member]
Disclosure of operating segments [Line Items]
Segment assets	(39,517,829)	(39,114,371)
Acquisition of non-current assets	23,616	(191,901)
Segment liabilities	(5,239,156)	(5,811,800)
Equity method adjustment [Member]
Disclosure of operating segments [Line Items]
Segment assets	754,314	906,239
Deferred taxes [Member]
Disclosure of operating segments [Line Items]
Segment assets	2,215	(5,830)
Segment liabilities	5,339,450	4,301,404
Others [Member]
Disclosure of operating segments [Line Items]
Segment assets	(11,478)	(10,723)
Segment liabilities	₩ (1,814,299)	₩ (1,108,823)

Geographical areas (Details)

Geographical areas (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue [Abstract]
Electricity		₩ 54,649,882	₩ 54,304,529	₩ 53,229,470
Heat supply		205,838	181,597	204,987
Others		916,828	893,361	932,579
Sales of goods		55,772,548	55,379,487	54,367,036
Sales of services		351,157	356,743	453,487
Sales of construction services		3,212,184	4,026,857	3,761,204
Total revenue from external customers		59,335,889	59,763,087	58,581,727
Non-current assets	[1]	157,934,345	152,772,376	148,314,438
Domestic [Member]
Revenue [Abstract]
Electricity		54,649,882	54,304,529	53,229,470
Heat supply		205,838	181,597	204,987
Others		517,596	495,969	527,006
Sales of goods		55,373,316	54,982,095	53,961,463
Sales of services		186,990	195,697	209,189
Sales of construction services		92,501	132,219	180,424
Total revenue from external customers		55,652,807	55,310,011	54,351,076
Non-current assets	[1]	153,436,810	148,297,677	143,788,043
Overseas [Member]
Revenue [Abstract]
Others		399,232	397,392	405,573
Sales of goods		399,232	397,392	405,573
Sales of services		164,167	161,046	244,298
Sales of construction services		3,119,683	3,894,638	3,580,780
Total revenue from external customers	[2]	3,683,082	4,453,076	4,230,651
Non-current assets	[1],[2]	₩ 4,497,535	₩ 4,474,699	₩ 4,526,395
[1]	Amount excludes financial assets and deferred tax assets.
[2]	Middle East and other Asian countries make up the majority of overseas revenue and non-current assets.

Classification of Financial 118

Classification of Financial Instruments - Classification of financial assets (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Classification by categories of financial assets [Line Items]
Cash and cash equivalents	₩ 2,369,739	₩ 3,051,353	₩ 3,783,065	₩ 1,796,300
Categories of current financial assets [Abstract]
Held-to-maturity investments	5	114
Derivative assets	12,935	193,283
Other financial assets	1,945,417	2,478,592
Trade and other receivables	7,928,972	7,788,876
Total current financial assets And Cash and cash equivalents	12,257,068	13,512,218
Non-Financial Assets [Abstract]
Available-for-sale financial assets	699,833	1,014,732
Held-to-maturity investments	3,139	3,130
Derivative assets	19,691	588,091
Other financial assets	1,316,250	1,051,541
Trade and other receivables	1,754,797	1,903,515
Total non-current financial assets	3,793,710	4,561,009
Total financial assets	16,050,778	18,073,227
Financial assets at fair value through profit or loss [Member]
Categories of current financial assets [Abstract]
Derivative assets	12,923	79,709
Total current financial assets And Cash and cash equivalents	12,923	79,709
Non-Financial Assets [Abstract]
Derivative assets	9,097	287,768
Other financial assets	111,512
Total non-current financial assets	120,609	287,768
Total financial assets	133,532	367,477
Loans and receivables [Member]
Disclosure of Classification by categories of financial assets [Line Items]
Cash and cash equivalents	2,369,739	3,051,353
Categories of current financial assets [Abstract]
Other financial assets	1,945,417	2,478,592
Trade and other receivables	7,928,972	7,788,876
Total current financial assets And Cash and cash equivalents	12,244,128	13,318,821
Non-Financial Assets [Abstract]
Other financial assets	1,204,738	1,051,541
Trade and other receivables	1,754,797	1,903,515
Total non-current financial assets	2,959,535	2,955,056
Total financial assets	15,203,663	16,273,877
Financial assets available-for-sale [Member]
Non-Financial Assets [Abstract]
Available-for-sale financial assets	699,833	1,014,732
Total non-current financial assets	699,833	1,014,732
Total financial assets	699,833	1,014,732
Held-to-maturity investments [Member]
Categories of current financial assets [Abstract]
Held-to-maturity investments	5	114
Total current financial assets And Cash and cash equivalents	5	114
Non-Financial Assets [Abstract]
Held-to-maturity investments	3,139	3,130
Total non-current financial assets	3,139	3,130
Total financial assets	3,144	3,244
Derivative assets (using hedge accounting) [Member]
Categories of current financial assets [Abstract]
Derivative assets	12	113,574
Total current financial assets And Cash and cash equivalents	12	113,574
Non-Financial Assets [Abstract]
Derivative assets	10,594	300,323
Total non-current financial assets	10,594	300,323
Total financial assets	₩ 10,606	₩ 413,897

Classification of Financial 119

Classification of Financial Instruments - Classification of financial liabilities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Categories of current financial liabilities [Abstract]
Borrowings	₩ 1,165,985	₩ 1,115,521
Debt securities	7,957,300	7,823,557
Derivative liabilities	71,267	3,251
Trade and other payables	5,999,521	5,585,411
Total current financial liabilities	15,194,073	14,527,740
Categories of non-current financial liabilities [Abstract]
Borrowings	2,434,624	1,773,891
Debt securities	43,189,483	42,926,236
Derivative liabilities	356,792	135,435
Trade and other payables	3,223,480	3,558,175
Total non-current financial liabilities	49,204,379	48,393,737
Total financial liabilities	64,398,452	62,921,477
Financial liabilities at fair value through profit or loss [Member]
Categories of current financial liabilities [Abstract]
Derivative liabilities	51,090	3,251
Total current financial liabilities	51,090	3,251
Categories of non-current financial liabilities [Abstract]
Derivative liabilities	99,839	18,278
Total non-current financial liabilities	99,839	18,278
Total financial liabilities	150,929	21,529
Financial liabilities recognized at amortized cost [Member]
Categories of current financial liabilities [Abstract]
Borrowings	1,165,985	1,115,521
Debt securities	7,957,300	7,823,557
Trade and other payables	5,999,521	5,585,411
Total current financial liabilities	15,122,806	14,524,489
Categories of non-current financial liabilities [Abstract]
Borrowings	2,434,624	1,773,891
Debt securities	43,189,483	42,926,236
Trade and other payables	3,223,480	3,558,175
Total non-current financial liabilities	48,847,587	48,258,302
Total financial liabilities	63,970,393	62,782,791
Derivative liabilities (using hedge accounting) [Member]
Categories of current financial liabilities [Abstract]
Derivative liabilities	20,177
Total current financial liabilities	20,177
Categories of non-current financial liabilities [Abstract]
Derivative liabilities	256,953	117,157
Total non-current financial liabilities	256,953	117,157
Total financial liabilities	₩ 277,130	₩ 117,157

Classification of Financial 120

Classification of Financial Instruments - Classification of comprehensive income (loss) from financial instruments (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		₩ 206,143	₩ 241,778	₩ 241,585
Dividend income		11,477	9,446	14,069
Impairment of available-for-sale financial assets		(2,713)	(86,703)	(84,370)
Gain (loss) on valuation of derivatives		(874,667)	288,068	593,531
Gain on valuation of financial assets		12
Interest expense of trade and other payables		(57,160)	(68,375)	(84,527)
Interest expense of others		(491,665)	(482,428)	(538,680)
Cash and Cash Equivalents [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		35,474	61,380	54,687
Financial assets available-for-sale [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income				29
Dividend income		11,477	9,446	14,069
Impairment of available-for-sale financial assets		(2,713)	(86,703)	(84,370)
Gain (loss) on disposal of available-for-sale financial assets		(1,213)	1,473	(3,004)
Held-to-maturity investments [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		82	97	99
Loans and receivables [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		30,014	25,106	28,586
Trade and other receivables [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		102,727	102,237	100,771
Short-term financial instruments [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		29,412	45,763	46,921
Long-term financial instruments [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		8,144	7,195	10,492
Financial assets at fair value through profit or loss [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest income		290
Gain (loss) on valuation of derivatives		(214,100)	113,671	220,285
Gain (loss) on transaction of derivatives		(37,266)	(8,039)	8,605
Gain on valuation of financial assets		12
Derivative assets (using hedge accounting) [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Gain (loss) on valuation of derivatives		(41,129)	145,458	244,020
Gain (loss) on transaction of derivatives		(58,299)	(13,994)	2,818
Gain (loss) on valuation of derivatives (equity, before tax)	[1]	2,453	50,047	(12,572)
Financial liabilities recognized at amortized cost [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Interest expense of borrowings and debt securities		(1,240,727)	(1,202,065)	(1,392,477)
Interest expense of trade and other payables		(57,160)	(68,375)	(84,527)
Interest expense of others		(491,665)	(482,428)	(538,680)
Loss on retirement of financial liabilities		(5)	(23,000)	(33)
Gain (loss) on foreign currency transactions and translations		1,075,215	(290,485)	(708,178)
Financial liabilities at fair value through profit or loss [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Gain (loss) on valuation of derivatives		(179,879)	23,225	35,312
Gain (loss) on transaction of derivatives		(27,175)	17,045	107,454
Derivative liabilities (using hedge accounting) [Member]
Income, expense, gains or losses of financial instruments [Abstract]
Gain (loss) on valuation of derivatives		(439,559)	5,714	93,914
Gain (loss) on transaction of derivatives		(46,221)	(51,450)	(4,288)
Gain (loss) on valuation of derivatives (equity, before tax)	[1]	₩ 29,431	₩ (3,297)	₩ 9,728
[1]	Items are included in other comprehensive income or loss. All other income and gain amounts listed above are included in finance income, and all expense and losses listed above are included in finance expenses in the consolidated statements of comprehensive income or loss.

Restricted Deposits (Details)

Restricted Deposits (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents, Current [Abstract]
Escrow accounts		₩ 53	₩ 91
Deposits for government project		15,365	16,457
Collateral provided for borrowings		79,569	80,327
Collateral provided for lawsuit		2	241
Deposits for transmission regional support program		2,320	2,137
Non-current available-for-sale financial asset [Abstract]
Decommissioning costs of nuclear power plants		214,156	437,015
Short-term financial instruments [Abstract]
Bidding guarantees		119	118
Restriction on withdrawal related to 'win-win growth program' for small and medium enterprises		34,000	33,000
Other current receivables [Abstract]
Deposit for lawsuit			16,000
Financial assets at fair value through profit or loss [Abstract]
Decommissioning costs of nuclear power plants		108,512
Long-term financial instruments [Abstract]
Guarantee deposits for checking account		2	2
Guarantee deposits for banking accounts at oversea branches		302	342
Decommissioning costs of nuclear power plants		337,234	214,121
Funds for developing small and medium enterprises	[1]	200,000	200,000
Total Restricted Deposits		₩ 991,634	₩ 999,851
[1]	Deposits for small and medium enterprise at IBK and others for construction of Bitgaram Energy Valley and support for the high potential businesses as of December 31, 2017 and 2016.

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Total cash	₩ 132	₩ 119
Demand Deposit Accounts	968,966	1,725,785
Short-term deposits, classified as cash equivalents	559,239	120,594
Short-term investments, classified as cash equivalents	841,402	1,204,855
Total cash and cash equivalents	₩ 2,369,739	₩ 3,051,353	₩ 3,783,065	₩ 1,796,300

Trade and Other Receivables - T

Trade and Other Receivables - Trade and other receivables (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trade and other current receivables [Abstract]
Trade receivables	₩ 7,325,702	₩ 7,188,242
Other receivables	603,270	600,634
Non-trade receivables	305,057	309,950
Accrued income	54,002	62,063
Deposits	226,574	191,643
Finance lease receivables	13,067	12,225
Others	4,570	24,753
Subtotal of current tade and other receivables	7,928,972	7,788,876
Trade and other non-current receivables [Abstract]
Trade receivables	448,777	491,509
Other non-current receivables	1,306,020	1,412,006
Non-trade receivables	53,866	53,451
Accrued income	182	174
Deposits	324,917	314,671
Finance lease receivables	849,554	960,649
Others	77,501	83,061
Subtotal of non-current tade and other receivables	1,754,797	1,903,515
Total trade and other receivables	9,683,769	9,692,391
Gross amount [Member]
Trade and other current receivables [Abstract]
Trade receivables	7,499,285	7,260,227
Other receivables	614,212	652,782
Non-trade receivables	314,256	360,021
Accrued income	54,002	62,063
Deposits	228,317	193,720
Finance lease receivables	13,067	12,225
Others	4,570	24,753
Subtotal of current tade and other receivables	8,113,497	7,913,009
Trade and other non-current receivables [Abstract]
Trade receivables	449,191	491,509
Other non-current receivables	1,380,983	1,455,860
Non-trade receivables	112,983	80,393
Accrued income	182	174
Deposits	331,071	320,935
Finance lease receivables	849,554	960,649
Others	87,193	93,709
Subtotal of non-current tade and other receivables	1,830,174	1,947,369
Total trade and other receivables	9,943,671	9,860,378
Allowance for Doubtful Accounts [Member]
Trade and other current receivables [Abstract]
Trade receivables	(173,583)	(71,985)
Other receivables	(9,199)	(50,071)
Non-trade receivables	(9,199)	(50,071)
Accrued income	0	0
Deposits	0	0
Finance lease receivables	0	0
Others	0	0
Subtotal of current tade and other receivables	(182,782)	(122,056)
Trade and other non-current receivables [Abstract]
Trade receivables	0	0
Other non-current receivables	(68,809)	(37,590)
Non-trade receivables	(59,117)	(26,942)
Accrued income	0	0
Deposits	0	0
Finance lease receivables	0	0
Others	(9,692)	(10,648)
Subtotal of non-current tade and other receivables	(68,809)	(37,590)
Total trade and other receivables	(251,591)	(159,646)
Present value discount [Member]
Trade and other current receivables [Abstract]
Trade receivables	0	0
Other receivables	(1,743)	(2,077)
Non-trade receivables	0	0
Accrued income	0	0
Deposits	(1,743)	(2,077)
Finance lease receivables	0	0
Others	0	0
Subtotal of current tade and other receivables	(1,743)	(2,077)
Trade and other non-current receivables [Abstract]
Trade receivables	(414)	0
Other non-current receivables	(6,154)	(6,264)
Non-trade receivables	0	0
Accrued income	0	0
Deposits	(6,154)	(6,264)
Finance lease receivables	0	0
Others	0	0
Subtotal of non-current tade and other receivables	(6,568)	(6,264)
Total trade and other receivables	₩ (8,311)	₩ (8,341)

Trade and Other Receivables - O

Trade and Other Receivables - Other receivables (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trade and Other Receivables [Line Items]
Trade receivables	₩ 7,774,479	₩ 7,679,751
Other receivables	1,909,290	2,012,640
Gross amount [Member]
Trade and Other Receivables [Line Items]
Trade receivables	7,948,476	7,751,736
Other receivables	1,995,195	2,108,642
Current [Member]
Trade and Other Receivables [Line Items]
Trade receivables	7,698,604	7,592,363
Other receivables	1,810,075	1,887,620
Less than 60 days [Member]
Trade and Other Receivables [Line Items]
Trade receivables	7,117	820
Other receivables	47,532	46,887
Trade and Other receivables: (impairment reviewed) [Member]
Trade and Other Receivables [Line Items]
Trade receivables	242,755	158,553
Other receivables	137,588	174,135
60 ~ 90 days [Member]
Trade and Other Receivables [Line Items]
Trade receivables	39,070	44,277
Other receivables	44	7,352
90 ~ 120 days [Member]
Trade and Other Receivables [Line Items]
Trade receivables	17,502	18,917
Other receivables	1,017	2,160
120 days ~ 1year [Member]
Trade and Other Receivables [Line Items]
Trade receivables	55,242	42,534
Other receivables	11,042	17,613
Over 1 year [Member]
Trade and Other Receivables [Line Items]
Trade receivables	130,941	52,825
Other receivables	125,485	147,010
Less: Allowance for doubtful accounts [Member]
Trade and Other Receivables [Line Items]
Trade receivables	(173,583)	(71,985)
Other receivables	(78,008)	(87,661)
Less: Present value discount [Member]
Trade and Other Receivables [Line Items]
Trade receivables	(414)
Other receivables	₩ (7,897)	₩ (8,341)

Trade and Other Receivables - C

Trade and Other Receivables - Changes in the allowance for doubtful accounts (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Trade receivables [Member]
Reconciliation of changes in allowance account for credit losses of financial assets [Line Items]
Beginning balance	₩ 71,985	₩ 51,956	₩ 80,644
Changes in allowance account for credit losses of financial assets [abstract]
Bad debt expense	126,714	38,719	1,308
Write-off	(32,995)	(18,939)	(28,978)
Reversal			(1,018)
Others	7,879	249
Ending balance	173,583	71,985	51,956
Other receivables [Member]
Reconciliation of changes in allowance account for credit losses of financial assets [Line Items]
Beginning balance	87,661	91,746	67,932
Changes in allowance account for credit losses of financial assets [abstract]
Bad debt expense	1,778	233	18,473
Write-off	(3,129)	(928)	(888)
Reversal	(2,166)	(5,489)	(413)
Others	(6,136)	2,099	6,642
Ending balance	₩ 78,008	₩ 87,661	₩ 91,746

Changes in available-for-sale f

Changes in available-for-sale financial assets (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Changes in available-for-sale financial assets [Line Items]
Beginning balance	₩ 1,014,732		₩ 584,479
Acquisition	233,285		449,484
Disposal	(461,423)	[1]	(5,226)	[2]
Valuation	5,248		61,793
Impairment	(2,713)		(86,703)		₩ (84,370)
Others	(89,296)		10,905
Ending Balance	699,833		1,014,732		584,479
Listed equity securities [Member]
Changes in available-for-sale financial assets [Line Items]
Beginning balance	268,171		196,579
Acquisition	106
Disposal	0		(3,398)	[2]
Valuation	8,156		74,139
Impairment	(97)		(9,122)
Others	(1,883)		9,973
Ending Balance	274,453		268,171		196,579
Unlisted equity securities [Member]
Changes in available-for-sale financial assets [Line Items]
Beginning balance	746,561		387,900
Acquisition	233,179		449,484
Disposal	(461,423)	[1]	(1,828)	[2]
Valuation	(2,908)		(12,346)
Impairment	(2,616)		(77,581)
Others	(87,413)		932
Ending Balance	₩ 425,380		₩ 746,561		₩ 387,900
[1]	The Company recognized gain and loss on disposal of available-for-sale financial assets amounted to ￦1,130 million and ￦2,343 million, respectively, from the partial sales of Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 and others for the year ended December 31, 2017.
[2]	The Company recognized gain and loss on disposal of available-for-sale financial assets amounted to ￦1,482 million and ￦9 million, respectively, from the sales of shares of Kwanglim Co., Ltd., TONGYANG Inc., TONGYANG networks Inc., Nexolon Co., Ltd. and SsangYong E&C Co., Ltd. and from the partial sales of IBK-AUCTUS Green Growth Private Equity Firm, Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 and Korea investment—Hanwha KT Master Lease Private Special Investment Trust for the year ended December 31, 2016.

Available-for-sale Financial127

Available-for-sale Financial Assets (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Available-for-sale financial assets [Line Items]
Acquisition cost		₩ 888,673		₩ 1,406,326
Book value		699,833		1,014,732		₩ 584,479
Fair value		661,907		974,647
Listed equity securities [Member]
Available-for-sale financial assets [Line Items]
Acquisition cost		365,891		365,773
Book value		274,453		268,171
Fair value		₩ 274,453		₩ 268,171
Korea District Heating Corp. [Member]
Available-for-sale financial assets [Line Items]
Shares		2,264,068		2,264,068
Ownership		19.55%		19.55%
Acquisition cost		₩ 173,201		₩ 173,201
Book value		165,277		154,183
Fair value		₩ 165,277		₩ 154,183
Ssangyong Motor Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		38,568		38,568
Ownership		0.03%		0.03%
Acquisition cost		₩ 428		₩ 428
Book value		197		304
Fair value		₩ 197		₩ 304
Sungjee Construction. Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		10,530		10,530
Ownership		0.01%		0.01%
Acquisition cost		₩ 49		₩ 49
Book value		8		21
Fair value		₩ 8		₩ 21
Korea Line Corp. [Member]
Available-for-sale financial assets [Line Items]
Shares		18		18
Ownership		0.00%		0.00%
Acquisition cost		₩ 1		₩ 1
Namkwang Engineering & Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		46		46
Ownership		0.00%		0.00%
Acquisition cost		₩ 15		₩ 15
Pumyang Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		35	[1]	7
Ownership		0.00%	[1]	0.00%
Acquisition cost		₩ 2	[1]	₩ 2
ELCOMTEC Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		32,875		32,875
Ownership		0.04%		0.04%
Acquisition cost		₩ 217		₩ 217
Book value		72		74
Fair value		₩ 72		₩ 74
PAN ocean Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,492		1,492
Ownership		0.00%		0.00%
Acquisition cost		₩ 14		₩ 14
Book value		8		7
Fair value		₩ 8		₩ 7
Borneo International Furniture Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				64,037
Ownership				0.28%
Acquisition cost				₩ 97
Book value				103
Fair value				₩ 103
Dongbu Corporation [Member]
Available-for-sale financial assets [Line Items]
Shares		955	[2]	1,229
Ownership		0.02%	[2]	0.02%
Acquisition cost		₩ 12	[2]	₩ 12
Book value		10	[2]	12
Fair value		₩ 10	[2]	₩ 12
KSP Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		6,324
Ownership		0.08%
Acquisition cost		₩ 24
Book value		24
Fair value		₩ 24
STX Heavy Industries Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		35,749
Ownership		0.14%
Acquisition cost		₩ 191
Book value		165
Fair value		₩ 165
PT Adaro Energy Tbk [Member]
Available-for-sale financial assets [Line Items]
Shares		480,000,000		480,000,000
Ownership		1.50%		1.50%
Acquisition cost		₩ 71,554		₩ 71,554
Book value		70,531		73,061
Fair value		₩ 70,531		₩ 73,061
Energy Fuels Inc. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,711,814		1,711,814
Ownership		2.38%		2.59%
Acquisition cost		₩ 16,819		₩ 16,819
Book value		3,300		3,385
Fair value		₩ 3,300		₩ 3,385
Baralaba Coal Company Limited [Member]
Available-for-sale financial assets [Line Items]
Shares		99,763		99,763	[3]
Ownership		0.07%		0.07%	[3]
Acquisition cost		₩ 18,445		₩ 18,445	[3]
Book value		22		42	[3]
Fair value		₩ 22		₩ 42	[3]
Denison Mines Corp. [Member]
Available-for-sale financial assets [Line Items]
Shares		58,284,000		58,284,000
Ownership		10.42%		10.93%
Acquisition cost		₩ 84,134		₩ 84,134
Book value		34,292		36,504
Fair value		₩ 34,292		₩ 36,504
Fission 3.0 [Member]
Available-for-sale financial assets [Line Items]
Shares		300,000		300,000
Ownership		0.14%		0.17%
Book value		₩ 15		₩ 16
Fair value		₩ 15		₩ 16
Fission Uranium Corp. [Member]
Available-for-sale financial assets [Line Items]
Shares		800,000		800,000
Ownership		0.16%		0.17%
Acquisition cost		₩ 785		₩ 785
Book value		532		459
Fair value		532		459
Unlisted equity securities [Member]
Available-for-sale financial assets [Line Items]
Acquisition cost	[4]	522,782		1,040,553
Book value	[4]	425,380		746,561
Fair value	[4]	₩ 387,454		₩ 706,476
K&C - Gyeongnam youth job creation Investment Fund [Member]
Available-for-sale financial assets [Line Items]
Shares				24
Ownership				10.00%
Acquisition cost				₩ 1,207
Book value				₩ 1,207
Korea investment – Korea EXIM Bank CERs Private Special Assets Investment Trust I [Member]
Available-for-sale financial assets [Line Items]
Shares		1,758,731,002		1,758,731,002
Ownership		14.18%		14.18%
Acquisition cost		₩ 1,752		₩ 1,752
Book value		₩ 571		₩ 571
Troika Overseas Resource Development Private Equity Firm [Member]
Available-for-sale financial assets [Line Items]
Shares		13,340,012,100		13,340,012,100
Ownership		3.66%		3.66%
Acquisition cost		₩ 13,340		₩ 13,340
Book value		₩ 1,553		₩ 1,553
IBK-AUCTUS Green Growth Private Equity firm [Member]
Available-for-sale financial assets [Line Items]
Shares		152		152
Ownership		6.29%		6.29%
Acquisition cost		₩ 41		₩ 41
Book value		₩ 41		₩ 41
Global Dynasty Overseas Resource Development Private Equity Firm [Member]
Available-for-sale financial assets [Line Items]
Shares		2,242,437,289		2,233,407,439
Ownership		7.46%		7.46%
Acquisition cost		₩ 2,242		₩ 2,233
Book value		₩ 2,242		₩ 2,233
Intellectual Discovery, Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,000,000		1,000,000
Ownership		8.81%		8.81%
Acquisition cost		₩ 5,000		₩ 5,000
Book value		₩ 954		₩ 1,375
Hanwha-KOSEP New Renewable Energy Private Special Assets Investment Trust 1 [Member]
Available-for-sale financial assets [Line Items]
Shares		4,176,751,013		4,256,096,329
Ownership		5.00%		5.00%
Acquisition cost		₩ 4,328		₩ 4,389
Book value		₩ 4,328		₩ 4,389
Construction Guarantee [Member]
Available-for-sale financial assets [Line Items]
Shares		571	[5]	571	[6]
Ownership		0.02%	[5]	0.02%	[6]
Acquisition cost		₩ 601	[5]	₩ 601	[6]
Book value		833	[5]	819	[6]
Fair value		₩ 833	[5]	₩ 819	[6]
Plant & Mechanical Contractors Financial Cooperative of Korea [Member]
Available-for-sale financial assets [Line Items]
Shares		144		50
Ownership		0.03%		0.01%
Acquisition cost		₩ 126		₩ 36
Book value		₩ 126		₩ 36
Fire Guarantee [Member]
Available-for-sale financial assets [Line Items]
Shares		40		40
Ownership		0.01%		0.02%
Acquisition cost		₩ 20		₩ 20
Book value		₩ 20		₩ 20
Korea Software Financial Cooperative [Member]
Available-for-sale financial assets [Line Items]
Shares		5,186		5,186
Ownership		1.09%		1.39%
Acquisition cost		₩ 3,301		₩ 3,301
Book value		₩ 3,301		₩ 3,301
Engineering Financial Cooperative [Member]
Available-for-sale financial assets [Line Items]
Shares		486		486
Ownership		0.05%		0.05%
Acquisition cost		₩ 60		₩ 60
Book value		₩ 60		₩ 60
Electric Contractors Financial Cooperative [Member]
Available-for-sale financial assets [Line Items]
Shares		1,000		800
Ownership		0.04%		0.03%
Acquisition cost		₩ 216		₩ 152
Book value		₩ 216		₩ 152
Korea Specialty Contractor Financial Cooperative [Member]
Available-for-sale financial assets [Line Items]
Shares		476		476
Ownership		0.01%		0.01%
Acquisition cost		₩ 417		₩ 417
Book value		₩ 417		₩ 417
Information & Communication Financial Cooperative [Member]
Available-for-sale financial assets [Line Items]
Shares		121		70
Ownership		0.02%		0.01%
Acquisition cost		₩ 26		₩ 10
Book value		₩ 26		₩ 10
Korea Electric Engineers Association [Member]
Available-for-sale financial assets [Line Items]
Shares		400		400
Ownership		0.24%		0.24%
Acquisition cost		₩ 40		₩ 40
Book value		₩ 40		₩ 40
Korea investment – Investment Pool for Public funds 10 [Member]
Available-for-sale financial assets [Line Items]
Ownership	[7]			0.00%
Acquisition cost	[7]			₩ 142,470
Book value	[7]			141,315
Fair value	[7]			₩ 141,315
Samsung investment – Investment Pool for Public funds 2 [Member]
Available-for-sale financial assets [Line Items]
Ownership	[7]			0.00%
Acquisition cost	[7]			₩ 213,710
Book value	[7]			211,920
Fair value	[7]			₩ 211,920
Samsung investment – Investment Pool for Public funds 1 [Member]
Available-for-sale financial assets [Line Items]
Ownership		0.00%	[8]	0.00%	[7]
Acquisition cost		₩ 53,220	[8]	₩ 53,220	[7]
Book value		53,739	[8]	53,212	[7]
Fair value		₩ 53,739	[8]	₩ 53,212	[7]
Korea investment – Hanwha KT Master Lease Private Special Investment Trust [Member]
Available-for-sale financial assets [Line Items]
Ownership		0.00%	[8]	0.00%	[7]
Acquisition cost		₩ 26,586	[8]	₩ 30,560	[7]
Book value		26,591	[8]	30,568	[7]
Fair value		₩ 26,591	[8]	₩ 30,568	[7]
Kyobo Royal-Class Repo Plus Fixed Income 1Y 2nd [Member]
Available-for-sale financial assets [Line Items]
Ownership	[8]	0.00%
Acquisition cost	[8]	₩ 33,000
Book value	[8]	33,008
Fair value	[8]	₩ 33,008
Kyobo Royal-Class Repo Plus Fixed Income 2Y 1st [Member]
Available-for-sale financial assets [Line Items]
Ownership	[8]	0.00%
Acquisition cost	[8]	₩ 50,000
Book value	[8]	50,399
Fair value	[8]	₩ 50,399
Kyobo Royal-Class Repo Plus A1 ABCP 1Y [Member]
Available-for-sale financial assets [Line Items]
Ownership	[8]	0.00%
Acquisition cost	[8]	₩ 50,000
Book value	[8]	50,419
Fair value	[8]	₩ 50,419
Hwan Young Steel Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		10,916		10,916
Ownership		0.14%		0.14%
Acquisition cost		₩ 1,092		₩ 1,092
Book value		₩ 97		₩ 97
SAMBO AUTO. Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		15,066		15,066
Ownership		0.02%		0.02%
Acquisition cost		₩ 38		₩ 38
Book value		₩ 38		₩ 38
Mobo Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		504		504
Ownership		0.00%		0.00%
Acquisition cost		₩ 14		₩ 14
Book value		₩ 14		₩ 14
HANKOOK Silicon Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				3,005,208
Ownership				10.44%
Acquisition cost				₩ 7,513
Book value				₩ 1,495
Dae Kwang Semiconductor Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		589		589
Ownership		0.07%		0.07%
Acquisition cost		₩ 6		₩ 6
Book value		₩ 6		₩ 6
Sanbon Department Store [Member]
Available-for-sale financial assets [Line Items]
Shares		828		828
Ownership		0.01%		0.01%
Acquisition cost		₩ 124		₩ 124
Book value		₩ 3		₩ 3
Miju Steel Mfg. Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		99,804		99,804
Ownership		0.23%		0.23%
Acquisition cost		₩ 50		₩ 51
Book value		₩ 50		₩ 51
BnB Sungwon Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				589
Ownership				0.07%
Acquisition cost				₩ 15
Book value				₩ 15
Sungwon Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		589
Ownership		0.07%
Acquisition cost		₩ 15
Book value		₩ 15
Hana Civil Engineering Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		23		23
Ownership		0.00%		0.00%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
KC Development Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		839		839
Ownership		0.02%		0.02%
Acquisition cost		₩ 6		₩ 6
Book value		₩ 6		₩ 6
IMHWA Corp. [Member]
Available-for-sale financial assets [Line Items]
Shares		329		329
Ownership		0.11%		0.11%
Acquisition cost		₩ 5		₩ 5
Book value		₩ 5		₩ 5
DALIM Special Vehicle Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		58		58
Ownership		0.08%		0.08%
Acquisition cost		₩ 10		₩ 10
Book value		₩ 10		₩ 10
ASA JEONJU Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		34,846		34,846
Ownership		1.34%		1.34%
Acquisition cost		₩ 697		₩ 697
Book value		₩ 69		₩ 69
Moonkyung Silica Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		42		42
Ownership		0.56%		0.56%
Sungkwang Timber Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		9		9
Ownership		0.34%		0.34%
Acquisition cost		₩ 4		₩ 4
Book value		₩ 4		₩ 4
Yongbo Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		61		61
Ownership		0.20%		0.20%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
HJ Steel Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		218		218
Ownership		0.07%		0.07%
Acquisition cost		₩ 2		₩ 2
Book value		₩ 2		₩ 2
KS Remicon Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		12		12
Ownership		0.04%		0.04%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
SIN-E Steel Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				109
Ownership				0.08%
Acquisition cost				₩ 33
Book value				₩ 33
Joongang Platec Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		3,591		3,591
Ownership		0.75%		0.75%
Acquisition cost		₩ 72		₩ 72
Book value		₩ 35		₩ 35
Pyungsan SI Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		434		434
Ownership		0.01%		0.01%
Acquisition cost		₩ 9		₩ 9
Book value		₩ 9		₩ 9
Samgong Development Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		12		12
Ownership		0.01%		0.01%
Acquisition cost		₩ 7		₩ 7
Book value		₩ 7		₩ 7
Joongang Development Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		540		540
Ownership		0.12%		0.12%
Acquisition cost		₩ 8		₩ 8
Book value		₩ 8		₩ 8
AJS Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		12,906		12,906
Ownership		0.23%		0.23%
Acquisition cost		₩ 32		₩ 32
Book value		₩ 32		₩ 32
SHIN-E B&P Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		119		119
Ownership		0.13%		0.13%
Acquisition cost		₩ 10		₩ 10
Book value		₩ 10		₩ 10
MSE Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		429		429
Ownership		0.13%		0.13%
Acquisition cost		₩ 9		₩ 9
Book value		₩ 9		₩ 9
Ilrim Nano Tec Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,520		1,520
Ownership		0.07%		0.07%
Acquisition cost		₩ 15		₩ 15
Book value		₩ 15		₩ 15
Youngjin Hi-Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		2,512		2,512
Ownership		0.25%		0.25%
Acquisition cost		₩ 126		₩ 126
Book value		₩ 21		₩ 21
Dong Woo International Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				90
Ownership				0.37%
Acquisition cost				₩ 18
Book value				₩ 18
Buyoung Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		270		270
Ownership		0.00%		0.00%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
Ilsuk Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		152		152
Ownership		0.17%		0.17%
Acquisition cost		₩ 10		₩ 10
Book value		₩ 10		₩ 10
Dongyang Telecom Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,760		1,760
Ownership		0.01%		0.01%
Acquisition cost		₩ 11		₩ 11
Book value		₩ 11		₩ 11
Han Young Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				35
Ownership				0.03%
Acquisition cost				₩ 3
Book value				₩ 3
Jongwon Remicon Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		31		31
Ownership		0.18%		0.18%
Acquisition cost		₩ 13		₩ 13
Book value		₩ 13		₩ 13
Ace Heat Treating Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		477		477
Ownership		1.43%		1.43%
Acquisition cost		₩ 72		₩ 72
Book value		₩ 72		₩ 72
Zyle Daewoo Motor Sales Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		22		22
Ownership		0.00%		0.00%
Daewoo Development Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		8		8
Ownership		0.00%		0.00%
Seyang Inc. [Member]
Available-for-sale financial assets [Line Items]
Shares		537		537
Ownership		0.05%		0.05%
Acquisition cost		₩ 27		₩ 27
Book value		₩ 27		₩ 27
Seungri Enterprise Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		93		93
Ownership		0.05%		0.05%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
Onggane Food Co., Ltd [Member]
Available-for-sale financial assets [Line Items]
Shares		5		5
Ownership		0.07%		0.07%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
Shin-E P&C Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		12		12
Ownership		0.00%		0.00%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
Ejung Ad Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		132		132
Ownership		0.09%		0.09%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
Solvus Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,056		1,056
Ownership		0.04%		0.04%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
Myung Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		89		89
Ownership		0.05%		0.05%
Acquisition cost		₩ 2		₩ 2
Book value		₩ 2		₩ 2
Emotion Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				167
Ownership				0.61%
Acquisition cost				₩ 8
Book value				₩ 8
Youngdong Concrete Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				32
Ownership				0.32%
Acquisition cost				₩ 7
Book value				₩ 7
Shinil Engineering Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		887		887
Ownership		0.06%		0.06%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
Biwang Industry Co., Ltd [Member]
Available-for-sale financial assets [Line Items]
Shares		406		406
Ownership		0.04%		0.04%
Acquisition cost		₩ 2		₩ 2
Book value		₩ 2		₩ 2
Huimun Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		263		263
Ownership		0.26%		0.26%
Acquisition cost		₩ 4		₩ 4
Book value		₩ 4		₩ 4
Young Sung Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		89		89
Ownership		0.40%		0.40%
Acquisition cost		₩ 26		₩ 27
Book value		₩ 26		₩ 27
Yuil Industrial Electronics Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		804		804
Ownership		0.32%		0.32%
Acquisition cost		₩ 15		₩ 16
Book value		₩ 15		₩ 16
DN TEK Inc. [Member]
Available-for-sale financial assets [Line Items]
Shares		12,401		12,401
Ownership		0.29%		0.29%
Acquisition cost		₩ 61		₩ 62
Book value		₩ 5		₩ 6
Daeyang F.M.S Corporation [Member]
Available-for-sale financial assets [Line Items]
Shares				593
Ownership				0.40%
Acquisition cost				₩ 23
Book value				₩ 23
Kwang Jin Structure Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		3,072		3,072
Ownership		0.60%		0.60%
Acquisition cost		₩ 31		₩ 31
Book value		₩ 31		₩ 31
Woojin Industry Corporation [Member]
Available-for-sale financial assets [Line Items]
Shares		3		3
Ownership		0.00%		0.00%
Acquisition cost		₩ 16		₩ 16
Book value		₩ 16		₩ 16
Kwang Sung Industry Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		325		325
Ownership		0.35%		0.35%
Acquisition cost		₩ 7		₩ 7
Book value		₩ 7		₩ 7
Futech Mold Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		274		274
Ownership		0.27%		0.27%
Acquisition cost		₩ 14		₩ 14
Book value		₩ 14		₩ 14
Samcheonri Industrial Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				533
Ownership				0.98%
Acquisition cost				₩ 13
Book value				₩ 13
Woojoo Environment Ind. Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		101		101
Ownership		0.11%		0.11%
Acquisition cost		₩ 13		₩ 13
Book value		₩ 13		₩ 13
Cheongatti Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		57		57
Ownership		0.10%		0.10%
Acquisition cost		₩ 4		₩ 4
Book value		₩ 4		₩ 4
Hyungji Esquire Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		55		55
Ownership		0.02%		0.02%
Acquisition cost		₩ 22		₩ 22
Book value		₩ 22		₩ 22
Kolmar Pharma Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,426		1,426
Ownership		0.01%		0.01%
Acquisition cost		₩ 52		₩ 52
Book value		₩ 3		₩ 3
Morado Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		209		209
Ownership		0.04%		0.04%
Acquisition cost		₩ 2		₩ 2
Book value		₩ 2		₩ 2
Myung Sung Tex Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		20		20
Ownership		0.00%		0.00%
Acquisition cost		₩ 2		₩ 2
Book value		₩ 2		₩ 2
Kwang Sung Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		610		610
Ownership		0.53%		0.53%
Acquisition cost		₩ 31		₩ 31
Book value		₩ 31		₩ 31
EverTechno. Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		29,424		29,424
Ownership		0.73%		0.73%
Acquisition cost		₩ 148		₩ 147
Book value		₩ 7		₩ 7
Autowel Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		260		260
Ownership		0.38%		0.38%
Acquisition cost		₩ 14		₩ 13
Book value		₩ 14		₩ 13
Woobang Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		8		8
Ownership		0.00%		0.00%
Acquisition cost		₩ 8		₩ 8
Book value		₩ 8		₩ 8
Shin Pyung Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		6		6
Ownership		0.03%		0.03%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
JMC Heavy Industries Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		2,724		2,724
Ownership		0.10%		0.10%
Acquisition cost		₩ 27		₩ 27
Book value		₩ 27		₩ 27
Najin Steel Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		37		37
Ownership		0.06%		0.06%
Acquisition cost		₩ 5		₩ 5
Book value		₩ 5		₩ 5
Sinkwang Industry Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,091		1,091
Ownership		1.68%		1.68%
Acquisition cost		₩ 5		₩ 5
Book value		₩ 5		₩ 5
Join Land Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				33
Ownership				0.00%
Acquisition cost				₩ 1
Book value				₩ 1
Crystal Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		22		22
Ownership		0.07%		0.07%
Acquisition cost		₩ 2		₩ 2
Book value		₩ 2		₩ 2
Elephant & Friends Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		563		563
Ownership		0.61%		0.61%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
Mireco Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		109		109
Ownership		0.25%		0.25%
Acquisition cost		₩ 11		₩ 11
Book value		₩ 11		₩ 11
L&K Industry Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,615		1,615
Ownership		0.60%		0.60%
Acquisition cost		₩ 24		₩ 24
Book value		₩ 24		₩ 24
JO Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,263		1,263
Ownership		0.62%		0.62%
Acquisition cost		₩ 25		₩ 25
Book value		₩ 25		₩ 25
Kendae Printing Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		422		422
Ownership		0.60%		0.60%
Acquisition cost		₩ 21		₩ 21
Book value		₩ 21		₩ 21
Dauning Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		231		231
Ownership		0.41%		0.41%
Acquisition cost		₩ 6		₩ 6
Book value		₩ 6		₩ 6
Korea Trecision Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		22		22
Ownership		0.45%		0.45%
Acquisition cost		₩ 5		₩ 5
Book value		₩ 5		₩ 5
Ace Track Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		3,130		3,130
Ownership		1.08%		1.08%
Acquisition cost		₩ 219		₩ 219
Book value		₩ 59		₩ 59
Taebok Machinery Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		109		109
Ownership		1.08%		1.08%
Acquisition cost		₩ 11		₩ 11
Book value		₩ 11		₩ 11
Yooah Industry Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				130
Ownership				0.02%
Acquisition cost				₩ 13
Book value				₩ 13
Yoo-A Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		105		105
Ownership		0.20%		0.20%
Acquisition cost		₩ 11		₩ 11
Book value		₩ 11		₩ 11
Dung Hwan Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		531		531
Ownership		0.02%		0.02%
Acquisition cost		₩ 5		₩ 5
Book value		₩ 5		₩ 5
Hurim Biocell Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		113		113
Ownership		0.00%		0.00%
Acquisition cost		₩ 5		₩ 5
Book value		₩ 5		₩ 5
P. J, Trading Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				12
Ownership				0.04%
Sunjin Power Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		4,941		4,941
Ownership		0.92%		0.92%
Acquisition cost		₩ 247		₩ 247
Book value		₩ 32		₩ 90
Smart Power Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		133,333		133,333
Ownership		4.83%		5.55%
Acquisition cost		₩ 200		₩ 200
Book value		₩ 200		₩ 200
Haseung Industries Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		55		55
Ownership		0.62%		0.62%
Acquisition cost		₩ 28		₩ 28
Book value		₩ 28		₩ 28
Beer Yeast Korea Inc. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,388		1,388
Ownership		0.43%		0.43%
Acquisition cost		₩ 7		₩ 7
Book value		₩ 7		₩ 7
Daeryung Corporation [Member]
Available-for-sale financial assets [Line Items]
Shares		207		207
Ownership		0.19%		0.19%
Acquisition cost		₩ 10		₩ 10
Book value		₩ 10		₩ 10
Korea Bio Red Ginseng Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		194		194
Ownership		0.09%		0.09%
Acquisition cost		₩ 10		₩ 10
Book value		₩ 10		₩ 10
ENH Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,086		1,086
Ownership		0.19%		0.19%
Acquisition cost		₩ 54		₩ 54
Book value		₩ 54		₩ 54
OCO Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				123
Ownership				0.37%
Acquisition cost				₩ 11
Book value				₩ 11
B CON Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		96		96
Ownership		1.16%		1.16%
Acquisition cost		₩ 6		₩ 6
Book value		₩ 6		₩ 6
Chunil Metal Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		11		11
Ownership		0.15%		0.15%
Acquisition cost		₩ 4		₩ 4
Book value		₩ 4		₩ 4
Teakwang Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				2,460
Ownership				0.11%
Acquisition cost				₩ 12
Book value				₩ 12
SsangMa Machine Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		4		4
Ownership		0.05%		0.05%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
SinJin Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		233		233
Ownership		0.30%		0.30%
Acquisition cost		₩ 9		₩ 9
Book value		₩ 9		₩ 9
Ace Integration Co., Ltd [Member]
Available-for-sale financial assets [Line Items]
Shares		105		93
Ownership		0.09%		0.09%
Acquisition cost		₩ 24		₩ 21
Book value		₩ 24		₩ 21
AceInti Agricultural Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		16		3
Ownership		0.02%		0.00%
Acquisition cost		₩ 5		₩ 1
Book value		₩ 5		₩ 1
KyungDong Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		130		130
Ownership		0.01%		0.01%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
ChunWon Development Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		193		193
Ownership		0.19%		0.19%
Acquisition cost		₩ 39		₩ 39
Book value		₩ 39		₩ 39
WonIl Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		999		999
Ownership		0.15%		0.15%
Acquisition cost		₩ 50		₩ 50
Book value		₩ 50		₩ 50
SungLim Industrial Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		29		29
Ownership		0.03%		0.03%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
DaeHa Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares				141
Ownership				0.54%
Acquisition cost				₩ 11
Book value				₩ 11
Korea Minerals Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		191		191
Ownership		0.05%		0.05%
Acquisition cost		₩ 134		₩ 135
Book value		₩ 1		₩ 135
HyoDong Development Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		119		119
Ownership		0.15%		0.15%
Acquisition cost		₩ 24		₩ 24
Book value		₩ 24		₩ 24
Haspe Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		652		652
Ownership		0.55%		0.55%
Acquisition cost		₩ 20		₩ 20
Book value		₩ 20		₩ 20
JoHyun Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		350		350
Ownership		1.56%		1.56%
Acquisition cost		₩ 18		₩ 18
Book value		₩ 18		₩ 18
KC Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		5,107		5,107
Ownership		0.17%		0.17%
Acquisition cost		₩ 3		₩ 3
Book value		₩ 3		₩ 3
SeongJi Industrial Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		41		41
Ownership		0.05%		0.05%
Acquisition cost		₩ 1		₩ 1
Book value		₩ 1		₩ 1
Areva nc Expansion [Member]
Available-for-sale financial assets [Line Items]
Shares				1,077,124
Ownership				13.49%
Acquisition cost				₩ 288,443
Book value				98,472
Fair value				₩ 98,472
Navanakorn Electric Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		4,442,800	[9]	8,885,600	[10]
Ownership		26.93%	[9]	26.93%	[10]
Acquisition cost		₩ 17,216	[9]	₩ 17,216	[10]
Book value		₩ 16,410	[9]	₩ 18,509	[10]
PT. Kedap Saayq [Member]
Available-for-sale financial assets [Line Items]
Shares		671		671
Ownership		10.00%		10.00%
Acquisition cost		₩ 18,540		₩ 18,540
Set Holding [Member]
Available-for-sale financial assets [Line Items]
Shares		1,100,220	[11]	1,100,220	[12]
Ownership		2.50%	[11]	2.50%	[12]
Acquisition cost		₩ 229,255	[11]	₩ 229,255	[12]
Book value		170,242	[11]	170,170	[12]
Fair value		₩ 170,242	[11]	₩ 170,170	[12]
PT. Cirebon Energi Prasarana [Member]
Available-for-sale financial assets [Line Items]
Shares		22,420		22,420
Ownership		10.00%		10.00%
Acquisition cost		₩ 2,612		₩ 2,612
Book value		₩ 2,401		₩ 2,709
DongKwang SD, Inc. [Member]
Available-for-sale financial assets [Line Items]
Shares		524
Ownership		0.23%
Acquisition cost		₩ 13
Book value		₩ 13
Dong Yang Metal Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		2,951
Ownership		1.97%
Acquisition cost		₩ 15
Book value		₩ 15
Seyang Precision Ind.Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		829
Ownership		0.23%
Acquisition cost		₩ 41
Book value		₩ 41
Dooriwon Food System Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		13
Ownership		0.27%
Acquisition cost		₩ 1
Book value		₩ 1
ShinShin Co., Ltd [Member]
Available-for-sale financial assets [Line Items]
Shares		339
Ownership		1.12%
Acquisition cost		₩ 17
Book value		₩ 17
Kitorang Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		165
Ownership		0.24%
Acquisition cost		₩ 49
Book value		₩ 49
Sung Kwang Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		23
Ownership		0.37%
Acquisition cost		₩ 6
Book value		₩ 6
Hyundai Metal Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		3,757
Ownership		5.60%
Acquisition cost		₩ 1,416
Book value		₩ 1,416
Shinheung petrol. Co. Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		699
Ownership		0.14%
Acquisition cost		₩ 7
Book value		₩ 7
Force TEC Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		3,501
Ownership		0.02%
Acquisition cost		₩ 18
Book value		₩ 18
Haisung Industrial Systems Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		10,751
Ownership		0.24%
Acquisition cost		₩ 54
Book value		₩ 54
Samsung Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		486
Ownership		1.28%
Acquisition cost		₩ 97
Book value		₩ 97
Tae Hyung Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		28
Ownership		0.43%
Acquisition cost		₩ 20
Book value		₩ 20
Samyangplant Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		323
Ownership		0.60%
Acquisition cost		₩ 16
Book value		₩ 16
Younil Metal Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		41
Ownership		0.21%
Acquisition cost		₩ 21
Book value		₩ 21
Myungjin Tech Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		20
Ownership		0.54%
Acquisition cost		₩ 4
Book value		₩ 4
Hankook Machine Tools Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		719
Ownership		0.14%
Acquisition cost		₩ 72
Book value		₩ 72
Hankook Precision Ind Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		110
Ownership		0.06%
Acquisition cost		₩ 11
Book value		₩ 11
Borneo International Furniture Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		64,037
Ownership		0.28%
Acquisition cost		₩ 97
Book value		₩ 14
CJ Paradise Co.,Ltd [Member]
Available-for-sale financial assets [Line Items]
Shares		24
Ownership		0.02%
Acquisition cost		₩ 12
Book value		₩ 12
Han Young Technology Company Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		35
Ownership		0.00%
Jungdo Aluminium Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		8,527
Ownership		0.35%
Acquisition cost		₩ 128
Book value		₩ 128
Ilheung Metal Co, Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		280
Ownership		0.83%
Acquisition cost		₩ 28
Book value		₩ 28
STX Offshore & Shipbuilding Co., Ltd [Member]
Available-for-sale financial assets [Line Items]
Shares		8,622
Ownership		0.25%
Acquisition cost		₩ 1,078
Book value		₩ 1,078
Ptotronics Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		151
Ownership		0.07%
Acquisition cost		₩ 2
Book value		₩ 2
NFT Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		136
Ownership		0.40%
Acquisition cost		₩ 8
Book value		₩ 8
Echoroba Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		157
Ownership		0.02%
Acquisition cost		₩ 3
Book value		₩ 3
Hyundaitech Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		1,363
Ownership		0.87%
Acquisition cost		₩ 27
Book value		₩ 27
Eco Alux Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		239
Ownership		0.22%
Acquisition cost		₩ 48
Book value		₩ 48
Daekyung Industry Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		9,112
Ownership		0.94%
Acquisition cost		₩ 13
Book value		₩ 13
Dasan Material Co.Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		29
Ownership		0.04%
Fish World Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		47
Ownership		0.21%
Acquisition cost		₩ 2
Book value		₩ 2
SG Shinsung Engineering and Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		10
Ownership		0.00%
Acquisition cost		₩ 6
Book value		₩ 6
Samdo Industry Electric Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		48
Ownership		0.02%
Acquisition cost		₩ 1
Book value		₩ 1
Taejung Industries Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		9,268
Ownership		0.30%
Acquisition cost		₩ 5
Book value		₩ 5
Shinsei Trading Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		64
Ownership		0.72%
Acquisition cost		₩ 1
Book value		₩ 1
Dynamic Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		111
Ownership		0.19%
Acquisition cost		₩ 3
Book value		₩ 3
Green Alchemy Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		38,202
Ownership		1.48%
Acquisition cost		₩ 191
Book value		₩ 191
IQ Power Asia Inc. [Member]
Available-for-sale financial assets [Line Items]
Shares		16,179
Ownership		0.31%
Acquisition cost		₩ 81
Book value		₩ 81
Youone TBM Engineering & Construction Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		227,854
Ownership		0.27%
Acquisition cost		₩ 31
Book value		₩ 31
KM Leatech [Member]
Available-for-sale financial assets [Line Items]
Shares		1,648
Ownership		0.98%
Acquisition cost		₩ 8
Book value		₩ 8
Wonil T&I Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		229
Ownership		0.17%
Acquisition cost		₩ 23
Book value		₩ 23
Semist Co.,Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares		555
Ownership		0.80%
Acquisition cost		₩ 3
Book value		₩ 3
DS POWER Co., Ltd. [Member]
Available-for-sale financial assets [Line Items]
Shares	[13]	580,000
Ownership	[13]	2.34%
Acquisition cost	[13]	₩ 2,900
Book value	[13]	1,223
Fair value	[13]	₩ 1,223
[1]	The number of shares increased due to the stock split (5:1).
[2]	The number of shares owned has changed due to the stock merge (9:7) during the year ended December 31, 2017.
[3]	The number of shares owned has changed due to the stock merge (500:1) during the year ended December 31, 2016
[4]	Investments in unlisted equity securities held by the Company for which a quoted market price does not exist in an active market and fair value cannot be measured reliably were measured at cost less impairment, if any.
[5]	The Company has estimated the fair value of the investment in Construction Guarantee based upon the price which would be applied when the investment is returned. The Company has recognized the difference between its fair value and book value as a gain or loss on valuation of available-for-sale financial assets in other comprehensive income or loss during the year ended December 31, 2017.
[6]	The Company has estimated the fair value of the investment in Construction Guarantee based upon the price which would be applied when the investment is returned. The Company has recognized the difference between its fair value and book value as a gain or loss on valuation of available-for-sale financial assets in other comprehensive income or loss during the year ended December 31, 2016.
[7]	As of December 31, 2016, the Company invested in ￦437,015 million as beneficiary securities exclusively for payment of decommissioning cost of nuclear power plants. The Company has measured the fair value of the beneficiary securities based on its net asset value.
[8]	As of December 31, 2017, the Company invested in ￦285,769 million as beneficiary securities exclusively for payment of decommissioning cost of nuclear power plants. The Company has measured the fair value of the beneficiary securities based on its net asset value.
[9]	Although the Company holds more than 20% of the equity shares of these investments, the Company cannot exercise significant influence.
[10]	Although the Company holds more than 20% of the equity shares of these investments, the Company cannot exercise significant influence.
[11]	The Company has estimated the fair value of Set Holding by using the discounted cash flow method and has recognized the difference between its fair value and book value as gain or loss on valuation of available-for-sale financial assets in other comprehensive income or loss during the year ended December 31, 2017.
[12]	The Company has estimated the fair value of Set Holding by using the discounted cash flow method and has recognized the difference between its fair value and book value as gain or loss on valuation of available-for-sale financial assets in other comprehensive income or loss during the year ended December 31, 2016.
[13]	As described in note 17, this is reclassified to available-for-sale financial assets due to loss of significant influence of the Company.

Held-to-maturity Investments (D

Held-to-maturity Investments (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in held-to-maturity investments [Line Items]
Beginning balance	₩ 3,244	₩ 3,623
Acquisitions	250	149
Disposals	(350)	(528)
Others	0	0
Ending balance	3,144	3,244
Government bonds [Member]
Changes in held-to-maturity investments [Line Items]
Beginning balance	3,244	3,623
Acquisitions	250	149
Disposals	(350)	(528)
Others	0	0
Ending balance	₩ 3,144	₩ 3,244

Held-to-maturity Investments -

Held-to-maturity Investments - Liquidity classification (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in held-to-maturity investments [Line Items]
Beginning balance	₩ 3,244	₩ 3,623
Acquisitions	250	149
Disposals	(350)	(528)
Others	0	0
Ending balance	3,144	3,244
Current Held to maturity Investments [Member]
Changes in held-to-maturity investments [Line Items]
Beginning balance	114	380
Disposals	(113)	(380)
Others	4	114
Ending balance	5	114
NonCurrent Held to maturity Investments [Member]
Changes in held-to-maturity investments [Line Items]
Beginning balance	3,130	3,243
Acquisitions	250	149
Disposals	(237)	(148)
Others	(4)	(114)
Ending balance	₩ 3,139	₩ 3,130

Derivative Instrument (Details)

Derivative Instrument (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Derivative [Line Items]
Current derivative financial assets		₩ 12,935		₩ 193,283
Non-current derivative financial assets		19,691		588,091
Current derivative financial liabilities		71,267		3,251
Non-current derivative financial liabilities		356,792		135,435
Disclosure of Gain and loss on valuation and transaction of derivatives and included in finance income and costs in the consolidated statements of comprehensive income (loss) [Abstract]
Net income effects of valuation gain (loss)		(874,667)		288,068		₩ 593,531
Net income effects of transaction gain (loss)		(168,961)		(56,438)		114,589
Accumulated other comprehensive income (loss)		31,884	[1]	46,750	[1]	(2,844)
Currency forward [Member]
Derivative [Line Items]
Current derivative financial assets		45		8,370
Non-current derivative financial assets				32,806
Current derivative financial liabilities		7,862		1,153
Non-current derivative financial liabilities		1,278		34
Disclosure of Gain and loss on valuation and transaction of derivatives and included in finance income and costs in the consolidated statements of comprehensive income (loss) [Abstract]
Net income effects of valuation gain (loss)		(41,889)		15,993		357
Net income effects of transaction gain (loss)		(28,223)		4,266		8,523
Accumulated other comprehensive income (loss)		0		0		0
Currency swap [Member]
Derivative [Line Items]
Current derivative financial assets		12		184,913
Non-current derivative financial assets		15,711		540,057
Current derivative financial liabilities		61,997		0
Non-current derivative financial liabilities		296,098		56,612
Disclosure of Gain and loss on valuation and transaction of derivatives and included in finance income and costs in the consolidated statements of comprehensive income (loss) [Abstract]
Net income effects of valuation gain (loss)		(843,747)		253,035		431,565
Net income effects of transaction gain (loss)		(137,376)		(68,266)		75,752
Accumulated other comprehensive income (loss)		26,810	[1]	40,031	[1]	(6,926)
Interest rate swap [Member]
Derivative [Line Items]
Current derivative financial assets		0		0
Non-current derivative financial assets		2,697		4,705
Current derivative financial liabilities		1,408		2,098
Non-current derivative financial liabilities		59,416		78,789
Disclosure of Gain and loss on valuation and transaction of derivatives and included in finance income and costs in the consolidated statements of comprehensive income (loss) [Abstract]
Net income effects of valuation gain (loss)		6,909		8,517		161,609
Net income effects of transaction gain (loss)		(3,362)		7,562		30,314
Accumulated other comprehensive income (loss)		5,074	[1]	6,719	[1]	4,082
Others [Member]
Derivative [Line Items]
Current derivative financial assets		12,878	[2]	0
Non-current derivative financial assets	[2]	1,283		10,523
Current derivative financial liabilities		0		0
Non-current derivative financial liabilities		0		0
Disclosure of Gain and loss on valuation and transaction of derivatives and included in finance income and costs in the consolidated statements of comprehensive income (loss) [Abstract]
Net income effects of valuation gain (loss)		4,060		10,523		0
Net income effects of transaction gain (loss)		0		0		0
Accumulated other comprehensive income (loss)		₩ 0		₩ 0		₩ 0
[1]	For the year ended December 31, 2017, the net gain on valuation of derivatives applying cash flow hedge accounting of ￦20,868 million, net of tax, is included in other comprehensive income or loss.
[2]	The Company has a put option to sell shares of DS POWER Co., Ltd, a related party of the Company, and the fair value of the option is recorded in ‘Others’.

Derivative Currency swap forwar

Derivative Currency swap forward contract List (Details) - 12 months ended Dec. 31, 2017 ¥ in Thousands, $ in Thousands, ₩ in Millions	KRW (₩)	JPY (¥)	USD ($)
Currency forward contracts 1 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Apr. 10, 2014	Apr. 10, 2014	Apr. 10, 2014
Matrurity date	Jul. 12, 2021	Jul. 12, 2021	Jul. 12, 2021
Contract Amount Pay	₩ 55,120
Contract Amount Receive | $			$ 52,000
Contract exchange rate	1,060	1,060	1,060
Currency forward contracts 2 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Apr. 28, 2014	Apr. 28, 2014	Apr. 28, 2014
Matrurity date	Jul. 12, 2021	Jul. 12, 2021	Jul. 12, 2021
Contract Amount Pay	₩ 50,784
Contract Amount Receive | $			$ 48,000
Contract exchange rate	1,058	1,058	1,058
Currency forward contracts 3 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Bank of America	Bank of America	Bank of America
Contract date	Apr. 29, 2014	Apr. 29, 2014	Apr. 29, 2014
Matrurity date	Jul. 12, 2021	Jul. 12, 2021	Jul. 12, 2021
Contract Amount Pay	₩ 105,400
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,054	1,054	1,054
Currency forward contracts 4 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	May 9, 2014	May 9, 2014	May 9, 2014
Matrurity date	Jul. 12, 2021	Jul. 12, 2021	Jul. 12, 2021
Contract Amount Pay	₩ 104,600
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,046	1,046	1,046
Currency forward contracts 5 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Dec. 22, 2017	Dec. 22, 2017	Dec. 22, 2017
Matrurity date	Jul. 12, 2021	Jul. 12, 2021	Jul. 12, 2021
Contract Amount Pay	₩ 105,079
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,050.79	1,050.79	1,050.79
Currency forward contracts 6 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract date	Dec. 27, 2017	Dec. 27, 2017	Dec. 27, 2017
Matrurity date	Jul. 12, 2021	Jul. 12, 2021	Jul. 12, 2021
Contract Amount Pay	₩ 104,849
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,048.49	1,048.49	1,048.49
Currency forward contracts 7 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	CCB	CCB	CCB
Contract date	Dec. 7, 2017	Dec. 7, 2017	Dec. 7, 2017
Matrurity date	Jan. 11, 2018	Jan. 11, 2018	Jan. 11, 2018
Contract Amount Pay	₩ 10,921
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,092.14	1,092.14	1,092.14
Currency forward contracts 8 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract date	Nov. 27, 2017	Nov. 27, 2017	Nov. 27, 2017
Matrurity date	Jan. 3, 2018	Jan. 3, 2018	Jan. 3, 2018
Contract Amount Pay	₩ 5,439
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,087.70	1,087.70	1,087.70
Currency forward contracts 9 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Mizuho Bank	Mizuho Bank	Mizuho Bank
Contract date	Nov. 29, 2017	Nov. 29, 2017	Nov. 29, 2017
Matrurity date	Jan. 5, 2018	Jan. 5, 2018	Jan. 5, 2018
Contract Amount Pay	₩ 5,402
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,080.32	1,080.32	1,080.32
Currency forward contracts 10 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Nov. 30, 2017	Nov. 30, 2017	Nov. 30, 2017
Matrurity date	Jan. 8, 2018	Jan. 8, 2018	Jan. 8, 2018
Contract Amount Pay	₩ 5,437
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,087.35	1,087.35	1,087.35
Currency forward contracts 11 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Mizuho Bank	Mizuho Bank	Mizuho Bank
Contract date	Dec. 5, 2017	Dec. 5, 2017	Dec. 5, 2017
Matrurity date	Jan. 9, 2018	Jan. 9, 2018	Jan. 9, 2018
Contract Amount Pay	₩ 5,416
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,083.20	1,083.20	1,083.20
Currency forward contracts 12 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 11, 2017	Dec. 11, 2017	Dec. 11, 2017
Matrurity date	Jan. 12, 2018	Jan. 12, 2018	Jan. 12, 2018
Contract Amount Pay	₩ 10,922
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,092.20	1,092.20	1,092.20
Currency forward contracts 13 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Kookmin Bank	Kookmin Bank	Kookmin Bank
Contract date	Dec. 12, 2017	Dec. 12, 2017	Dec. 12, 2017
Matrurity date	Jan. 15, 2018	Jan. 15, 2018	Jan. 15, 2018
Contract Amount Pay	₩ 3,270
Contract Amount Receive | $			$ 3,000
Contract exchange rate	1,090.15	1,090.15	1,090.15
Currency forward contracts 14 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Kookmin Bank	Kookmin Bank	Kookmin Bank
Contract date	Dec. 13, 2017	Dec. 13, 2017	Dec. 13, 2017
Matrurity date	Jan. 16, 2018	Jan. 16, 2018	Jan. 16, 2018
Contract Amount Pay	₩ 10,906
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,090.55	1,090.55	1,090.55
Currency forward contracts 15 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Credit Suisse	Credit Suisse	Credit Suisse
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Jan. 17, 2018	Jan. 17, 2018	Jan. 17, 2018
Contract Amount Pay	₩ 10,858
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,085.80	1,085.80	1,085.80
Currency forward contracts 16 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Jan. 18, 2018	Jan. 18, 2018	Jan. 18, 2018
Contract Amount Pay	₩ 10,858
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,085.80	1,085.80	1,085.80
Currency forward contracts 17 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract date	Dec. 15, 2017	Dec. 15, 2017	Dec. 15, 2017
Matrurity date	Jan. 19, 2018	Jan. 19, 2018	Jan. 19, 2018
Contract Amount Pay	₩ 10,884
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,088.39	1,088.39	1,088.39
Currency forward contracts 18 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 18, 2017	Dec. 18, 2017	Dec. 18, 2017
Matrurity date	Jan. 22, 2018	Jan. 22, 2018	Jan. 22, 2018
Contract Amount Pay	₩ 10,881
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,088.14	1,088.14	1,088.14
Currency forward contracts 19 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Jan. 22, 2018	Jan. 22, 2018	Jan. 22, 2018
Contract Amount Pay	₩ 5,413
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,082.60	1,082.60	1,082.60
Currency forward contracts 20 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Mizuho Bank	Mizuho Bank	Mizuho Bank
Contract date	Dec. 21, 2017	Dec. 21, 2017	Dec. 21, 2017
Matrurity date	Jan. 26, 2018	Jan. 26, 2018	Jan. 26, 2018
Contract Amount Pay	₩ 10,802
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,080.20	1,080.20	1,080.20
Currency forward contracts 21 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Credit Suisse	Credit Suisse	Credit Suisse
Contract date	Dec. 22, 2017	Dec. 22, 2017	Dec. 22, 2017
Matrurity date	Jan. 26, 2018	Jan. 26, 2018	Jan. 26, 2018
Contract Amount Pay	₩ 10,778
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,077.75	1,077.75	1,077.75
Currency forward contracts 22 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Dec. 28, 2017	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 29, 2018	Jan. 29, 2018	Jan. 29, 2018
Contract Amount Pay	₩ 10,716
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,071.55	1,071.55	1,071.55
Currency forward contracts 23 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	CCB	CCB	CCB
Contract date	Dec. 28, 2017	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 30, 2018	Jan. 30, 2018	Jan. 30, 2018
Contract Amount Pay	₩ 10,706
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,070.60	1,070.60	1,070.60
Currency forward contracts 24 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 29, 2017	Dec. 29, 2017	Dec. 29, 2017
Matrurity date	Feb. 5, 2018	Feb. 5, 2018	Feb. 5, 2018
Contract Amount Pay	₩ 10,679
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,067.90	1,067.90	1,067.90
Currency forward contracts 25 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 5, 2017	Dec. 5, 2017	Dec. 5, 2017
Matrurity date	Jan. 5, 2018	Jan. 5, 2018	Jan. 5, 2018
Contract Amount Pay	₩ 2,170
Contract Amount Receive | $			$ 2,000
Contract exchange rate	1,084.92	1,084.92	1,084.92
Currency forward contracts 26 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 5, 2017	Dec. 5, 2017	Dec. 5, 2017
Matrurity date	Jan. 5, 2018	Jan. 5, 2018	Jan. 5, 2018
Contract Amount Pay	₩ 2,164
Contract Amount Receive | $			$ 2,000
Contract exchange rate	1,082.02	1,082.02	1,082.02
Currency forward contracts 27 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 7, 2017	Dec. 7, 2017	Dec. 7, 2017
Matrurity date	Jan. 5, 2018	Jan. 5, 2018	Jan. 5, 2018
Contract Amount Pay	₩ 6,551
Contract Amount Receive | $			$ 6,000
Contract exchange rate	1,091.77	1,091.77	1,091.77
Currency forward contracts 28 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Jan. 10, 2018	Jan. 10, 2018	Jan. 10, 2018
Contract Amount Pay	₩ 11,950
Contract Amount Receive | $			$ 11,000
Contract exchange rate	1,086.35	1,086.35	1,086.35
Currency forward contracts 29 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Jan. 10, 2018	Jan. 10, 2018	Jan. 10, 2018
Contract Amount Pay	₩ 10,865
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,086.45	1,086.45	1,086.45
Currency forward contracts 30 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BTMU	BTMU	BTMU
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Jan. 16, 2018	Jan. 16, 2018	Jan. 16, 2018
Contract Amount Pay	₩ 11,906
Contract Amount Receive | $			$ 11,000
Contract exchange rate	1,082.35	1,082.35	1,082.35
Currency forward contracts 31 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Jan. 16, 2018	Jan. 16, 2018	Jan. 16, 2018
Contract Amount Pay	₩ 15,130
Contract Amount Receive | $			$ 14,000
Contract exchange rate	1,080.70	1,080.70	1,080.70
Currency forward contracts 32 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	CCB	CCB	CCB
Contract date	Dec. 21, 2017	Dec. 21, 2017	Dec. 21, 2017
Matrurity date	Jan. 23, 2018	Jan. 23, 2018	Jan. 23, 2018
Contract Amount Pay	₩ 11,880
Contract Amount Receive | $			$ 11,000
Contract exchange rate	1,080	1,080	1,080
Currency forward contracts 33 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract date	Dec. 28, 2017	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 31, 2018	Jan. 31, 2018	Jan. 31, 2018
Contract Amount Pay	₩ 11,782
Contract Amount Receive | $			$ 11,000
Contract exchange rate	1,071.10	1,071.10	1,071.10
Currency forward contracts 34 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 28, 2017	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 23, 2018	Jan. 23, 2018	Jan. 23, 2018
Contract Amount Pay	₩ 33,209
Contract Amount Receive | $			$ 31,000
Contract exchange rate	1,071.25	1,071.25	1,071.25
Currency forward contracts 35 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Dec. 28, 2017	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 23, 2018	Jan. 23, 2018	Jan. 23, 2018
Contract Amount Pay	₩ 10,712
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,071.15	1,071.15	1,071.15
Currency forward contracts 36 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BTMU	BTMU	BTMU
Contract date	Dec. 28, 2017	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 31, 2018	Jan. 31, 2018	Jan. 31, 2018
Contract Amount Pay	₩ 10,712
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,071.20	1,071.20	1,071.20
Currency forward contracts 37 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Nov. 15, 2017	Nov. 15, 2017	Nov. 15, 2017
Matrurity date	Jan. 17, 2018	Jan. 17, 2018	Jan. 17, 2018
Contract Amount Pay	₩ 3,713
Contract Amount Receive | $			$ 3,349
Contract exchange rate	1,108.60	1,108.60	1,108.60
Currency forward contracts 38 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Nov. 15, 2017	Nov. 15, 2017	Nov. 15, 2017
Matrurity date	Jan. 22, 2018	Jan. 22, 2018	Jan. 22, 2018
Contract Amount Pay	₩ 8,837
Contract Amount Receive | $			$ 8,000
Contract exchange rate	1,104.60	1,104.60	1,104.60
Currency forward contracts 39 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BTMU	BTMU	BTMU
Contract date	Nov. 29, 2017	Nov. 29, 2017	Nov. 29, 2017
Matrurity date	Feb. 1, 2018	Feb. 1, 2018	Feb. 1, 2018
Contract Amount Pay	₩ 7,568
Contract Amount Receive | $			$ 7,000
Contract exchange rate	1,081.20	1,081.20	1,081.20
Currency forward contracts 40 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Nov. 29, 2017	Nov. 29, 2017	Nov. 29, 2017
Matrurity date	Feb. 1, 2018	Feb. 1, 2018	Feb. 1, 2018
Contract Amount Pay	₩ 7,557
Contract Amount Receive | $			$ 7,000
Contract exchange rate	1,079.60	1,079.60	1,079.60
Currency forward contracts 41 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Jan. 22, 2018	Jan. 22, 2018	Jan. 22, 2018
Contract Amount Pay	₩ 5,429
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,085.75	1,085.75	1,085.75
Currency forward contracts 42 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BTMU	BTMU	BTMU
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Feb. 22, 2018	Feb. 22, 2018	Feb. 22, 2018
Contract Amount Pay	₩ 10,822
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,082.18	1,082.18	1,082.18
Currency forward contracts 43 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Jan. 22, 2018	Jan. 22, 2018	Jan. 22, 2018
Contract Amount Pay	₩ 2,879
Contract Amount Receive | $			$ 2,661
Contract exchange rate	1,082	1,082	1,082
Currency forward contracts 44 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Jan. 22, 2018	Jan. 22, 2018	Jan. 22, 2018
Contract Amount Pay	₩ 5,406
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,081.10	1,081.10	1,081.10
Currency forward contracts 45 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nonghyup Bank	Nonghyup Bank	Nonghyup Bank
Contract date	Dec. 21, 2017	Dec. 21, 2017	Dec. 21, 2017
Matrurity date	Jan. 23, 2018	Jan. 23, 2018	Jan. 23, 2018
Contract Amount Pay	₩ 6,467
Contract Amount Receive | $			$ 6,000
Contract exchange rate	1,077.90	1,077.90	1,077.90
Currency forward contracts 46 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 27, 2017	Dec. 27, 2017	Dec. 27, 2017
Matrurity date	Jan. 29, 2018	Jan. 29, 2018	Jan. 29, 2018
Contract Amount Pay	₩ 5,366
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,073.15	1,073.15	1,073.15
Currency forward contracts 47 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 27, 2017	Dec. 27, 2017	Dec. 27, 2017
Matrurity date	Jan. 5, 2018	Jan. 5, 2018	Jan. 5, 2018
Contract Amount Pay	₩ 5,373
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,074.50	1,074.50	1,074.50
Currency forward contracts 48 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Nov. 23, 2017	Nov. 23, 2017	Nov. 23, 2017
Matrurity date	Jan. 11, 2018	Jan. 11, 2018	Jan. 11, 2018
Contract Amount Pay	₩ 9,237
Contract Amount Receive | $			$ 8,500
Contract exchange rate	1,086.76	1,086.76	1,086.76
Currency forward contracts 49 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Dec. 13, 2017	Dec. 13, 2017	Dec. 13, 2017
Matrurity date	Jan. 15, 2018	Jan. 15, 2018	Jan. 15, 2018
Contract Amount Pay	₩ 5,454
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,090.70	1,090.70	1,090.70
Currency forward contracts 50 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Dec. 8, 2017	Dec. 8, 2017	Dec. 8, 2017
Matrurity date	Jan. 25, 2018	Jan. 25, 2018	Jan. 25, 2018
Contract Amount Pay	₩ 10,921
Contract Amount Receive | $			$ 10,000
Contract exchange rate	1,092.05	1,092.05	1,092.05
Currency forward contracts 51 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 21, 2018	Feb. 21, 2018	Feb. 21, 2018
Contract Amount Pay	₩ 5,610
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,122	1,122	1,122
Currency forward contracts 52 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Nov. 29, 2017	Nov. 29, 2017	Nov. 29, 2017
Matrurity date	Feb. 21, 2018	Feb. 21, 2018	Feb. 21, 2018
Contract Amount Pay	₩ 7,572
Contract Amount Receive | $			$ 7,000
Contract exchange rate	1,081.65	1,081.65	1,081.65
Currency forward contracts 53 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Mar. 22, 2018	Mar. 22, 2018	Mar. 22, 2018
Contract Amount Pay	₩ 3,978
Contract Amount Receive | $			$ 3,682
Contract exchange rate	1,080.55	1,080.55	1,080.55
Currency forward contracts 54 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Mar. 22, 2018	Mar. 22, 2018	Mar. 22, 2018
Contract Amount Pay	₩ 5,399
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,079.75	1,079.75	1,079.75
Currency forward contracts 55 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Mar. 22, 2018	Mar. 22, 2018	Mar. 22, 2018
Contract Amount Pay	₩ 5,393
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,078.55	1,078.55	1,078.55
Currency forward contracts 56 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 20, 2017	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Mar. 22, 2018	Mar. 22, 2018	Mar. 22, 2018
Contract Amount Pay	₩ 5,393
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,078.65	1,078.65	1,078.65
Currency forward contracts 57 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Mar. 19, 2018	Mar. 19, 2018	Mar. 19, 2018
Contract Amount Pay	₩ 205
Contract Amount Receive | $			$ 189
Contract exchange rate	1,084.50	1,084.50	1,084.50
Currency forward contracts 58 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 3,164
Contract Amount Receive | $			$ 2,918
Contract exchange rate	1,084.20	1,084.20	1,084.20
Currency forward contracts 59 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 1,177
Contract Amount Receive | $			$ 1,087
Contract exchange rate	1,082.90	1,082.90	1,082.90
Currency forward contracts 60 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,418
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,083.60	1,083.60	1,083.60
Currency forward contracts 61 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,421
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,084.20	1,084.20	1,084.20
Currency forward contracts 62 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,413
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,082.60	1,082.60	1,082.60
Currency forward contracts 63 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,419
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,083.70	1,083.70	1,083.70
Currency forward contracts 64 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,422
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,084.30	1,084.30	1,084.30
Currency forward contracts 65 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,427
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,085.40	1,085.40	1,085.40
Currency forward contracts 66 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 19, 2017	Dec. 19, 2017	Dec. 19, 2017
Matrurity date	Mar. 21, 2018	Mar. 21, 2018	Mar. 21, 2018
Contract Amount Pay	₩ 5,430
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,085.90	1,085.90	1,085.90
Currency forward contracts 67 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Mar. 19, 2018	Mar. 19, 2018	Mar. 19, 2018
Contract Amount Pay	₩ 5,428
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,085.50	1,085.50	1,085.50
Currency forward contracts 68 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Dec. 14, 2017	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Mar. 19, 2018	Mar. 19, 2018	Mar. 19, 2018
Contract Amount Pay	₩ 5,428
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,085.50	1,085.50	1,085.50
Currency forward contracts 69 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Nov. 21, 2017	Nov. 21, 2017	Nov. 21, 2017
Matrurity date	Feb. 26, 2018	Feb. 26, 2018	Feb. 26, 2018
Contract Amount Pay	₩ 5,266
Contract Amount Receive | $			$ 4,826
Contract exchange rate	1,091.10	1,091.10	1,091.10
Currency forward contracts 70 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Nov. 21, 2017	Nov. 21, 2017	Nov. 21, 2017
Matrurity date	Feb. 26, 2018	Feb. 26, 2018	Feb. 26, 2018
Contract Amount Pay	₩ 5,461
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,092.10	1,092.10	1,092.10
Currency forward contracts 71 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Nov. 15, 2017	Nov. 15, 2017	Nov. 15, 2017
Matrurity date	Feb. 21, 2018	Feb. 21, 2018	Feb. 21, 2018
Contract Amount Pay	₩ 1,755
Contract Amount Receive | $			$ 1,587
Contract exchange rate	1,106.10	1,106.10	1,106.10
Currency forward contracts 72 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Nov. 15, 2017	Nov. 15, 2017	Nov. 15, 2017
Matrurity date	Feb. 21, 2018	Feb. 21, 2018	Feb. 21, 2018
Contract Amount Pay	₩ 5,536
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,107.10	1,107.10	1,107.10
Currency forward contracts 73 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Nov. 15, 2017	Nov. 15, 2017	Nov. 15, 2017
Matrurity date	Feb. 21, 2018	Feb. 21, 2018	Feb. 21, 2018
Contract Amount Pay	₩ 4,462
Contract Amount Receive | $			$ 4,027
Contract exchange rate	1,108.10	1,108.10	1,108.10
Currency forward contracts 74 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 6, 2018	Feb. 6, 2018	Feb. 6, 2018
Contract Amount Pay	₩ 711
Contract Amount Receive | $			$ 638
Contract exchange rate	1,112.80	1,112.80	1,112.80
Currency forward contracts 75 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 5, 2018	Feb. 5, 2018	Feb. 5, 2018
Contract Amount Pay	₩ 194
Contract Amount Receive | $			$ 173
Contract exchange rate	1,117.80	1,117.80	1,117.80
Currency forward contracts 76 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 5, 2018	Feb. 5, 2018	Feb. 5, 2018
Contract Amount Pay	₩ 5,594
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,118.80	1,118.80	1,118.80
Currency forward contracts 77 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,604
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,120.80	1,120.80	1,120.80
Currency forward contracts 78 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,599
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,119.80	1,119.80	1,119.80
Currency forward contracts 79 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,602
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,120.40	1,120.40	1,120.40
Currency forward contracts 80 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,604
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,120.70	1,120.70	1,120.70
Currency forward contracts 81 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,599
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,119.70	1,119.70	1,119.70
Currency forward contracts 82 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,604
Contract Amount Receive | $			$ 5,000
Contract exchange rate	1,120.70	1,120.70	1,120.70
Currency forward contracts 83 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 5,393
Contract Amount Receive | $			$ 4,817
Contract exchange rate	1,119.70	1,119.70	1,119.70
Currency forward contracts 84 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale
Contract date	Oct. 31, 2017	Oct. 31, 2017	Oct. 31, 2017
Matrurity date	Feb. 2, 2018	Feb. 2, 2018	Feb. 2, 2018
Contract Amount Pay	₩ 861
Contract Amount Receive | $			$ 768
Contract exchange rate	1,120.80	1,120.80	1,120.80
Currency forward contracts 85 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	Nova Scotia	Nova Scotia	Nova Scotia
Contract date	Oct. 26, 2017	Oct. 26, 2017	Oct. 26, 2017
Matrurity date	Jan. 30, 2018	Jan. 30, 2018	Jan. 30, 2018
Contract Amount Pay	₩ 923
Contract Amount Receive | $			$ 822
Contract exchange rate	1,123.40	1,123.40	1,123.40
Currency forward contracts 86 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas
Contract date	Oct. 13, 2017	Oct. 13, 2017	Oct. 13, 2017
Matrurity date	Jan. 18, 2018	Jan. 18, 2018	Jan. 18, 2018
Contract Amount Pay	₩ 652
Contract Amount Receive | $			$ 579
Contract exchange rate	1,125.60	1,125.60	1,125.60
Currency forward contracts 87 [Member]
Disclosure of Derivative Currency forward contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract date	Nov. 27, 2017	Nov. 27, 2017	Nov. 27, 2017
Matrurity date	Nov. 26, 2018	Nov. 26, 2018	Nov. 26, 2018
Contract Amount Pay | ¥		¥ 40,000
Contract Amount Receive	₩ 398
Contract exchange rate	9.94	9.94	9.94

Derivative Currency swap contra

Derivative Currency swap contract List (Details) - 12 months ended Dec. 31, 2017 € in Thousands, ¥ in Thousands, kr in Thousands, SFr in Thousands, $ in Thousands, $ in Thousands, ₩ in Millions	KRW (₩)	JPY (¥)	USD ($)	CHF (SFr)	AUD ($)	EUR (€)	SEK (kr)
Not Designated as Hedging Instrument [Member] | Currency swap contracts 1 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank
Contract Amount Pay	₩ 110,412
Contract Amount Receive | ¥		¥ 10,000
Contract exchange rate	11.04	11.04	11.04	11.04	11.04	11.04	11.04
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	6.21%	6.21%	6.21%	6.21%	6.21%	6.21%	6.21%
Contract Interest rate Receive	4.19%	4.19%	4.19%	4.19%	4.19%	4.19%	4.19%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 2 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	IBK	IBK	IBK	IBK	IBK	IBK	IBK
Contract Amount Pay	₩ 111,800
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,118	1,118	1,118	1,118	1,118	1,118	1,118
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.16%	3.16%	3.16%	3.16%	3.16%	3.16%	3.16%
Contract Interest rate Receive	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 3 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America
Contract Amount Pay	₩ 103,580
Contract Amount Receive | ¥		¥ 10,000,000
Contract exchange rate	10.36	10.36	10.36	10.36	10.36	10.36	10.36
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	7.05%	7.05%	7.05%	7.05%	7.05%	7.05%	7.05%
Contract Interest rate Receive	4.19%	4.19%	4.19%	4.19%	4.19%	4.19%	4.19%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 4 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse
Contract Amount Pay	₩ 118,632
Contract Amount Receive | SFr				SFr 100,000
Contract exchange rate	1,186.32	1,186.32	1,186.32	1,186.32	1,186.32	1,186.32	1,186.32
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	2.98%	2.98%	2.98%	2.98%	2.98%	2.98%	2.98%
Contract Interest rate Receive	1.50%	1.50%	1.50%	1.50%	1.50%	1.50%	1.50%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 5 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 114,903
Contract Amount Receive | SFr				SFr 100,000
Contract exchange rate	1,149.03	1,149.03	1,149.03	1,149.03	1,149.03	1,149.03	1,149.03
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	4.00%	4.00%	4.00%	4.00%	4.00%	4.00%	4.00%
Contract Interest rate Receive	1.50%	1.50%	1.50%	1.50%	1.50%	1.50%	1.50%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 6 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 102,470
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,024.70	1,024.70	1,024.70	1,024.70	1,024.70	1,024.70	1,024.70
Derivative, Term of Contract	2014~2029	2014~2029	2014~2029	2014~2029	2014~2029	2014~2029	2014~2029
Contract Interest rate Pay	3.14%	3.14%	3.14%	3.14%	3.14%	3.14%	3.14%
Contract Interest rate Receive	3.57%	3.57%	3.57%	3.57%	3.57%	3.57%	3.57%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 7 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale
Contract Amount Pay	₩ 105,017
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,050.17	1,050.17	1,050.17	1,050.17	1,050.17	1,050.17	1,050.17
Derivative, Term of Contract	2014~2024	2014~2024	2014~2024	2014~2024	2014~2024	2014~2024	2014~2024
Contract Interest rate Pay	4.92%	4.92%	4.92%	4.92%	4.92%	4.92%	4.92%
Contract Interest rate Receive	5.13%	5.13%	5.13%	5.13%	5.13%	5.13%	5.13%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 8 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 107,970
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,079.70	1,079.70	1,079.70	1,079.70	1,079.70	1,079.70	1,079.70
Derivative, Term of Contract	2015~2024	2015~2024	2015~2024	2015~2024	2015~2024	2015~2024	2015~2024
Contract Interest rate Pay	4.75%	4.75%	4.75%	4.75%	4.75%	4.75%	4.75%
Contract Interest rate Receive	5.13%	5.13%	5.13%	5.13%	5.13%	5.13%	5.13%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 9 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole
Contract Amount Pay	₩ 94,219
Contract Amount Receive | $			$ 86,920
Contract exchange rate	1,083.97	1,083.97	1,083.97	1,083.97	1,083.97	1,083.97	1,083.97
Derivative, Term of Contract	2015~2024	2015~2024	2015~2024	2015~2024	2015~2024	2015~2024	2015~2024
Contract Interest rate Pay	4.85%	4.85%	4.85%	4.85%	4.85%	4.85%	4.85%
Contract Interest rate Receive	5.13%	5.13%	5.13%	5.13%	5.13%	5.13%	5.13%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 10 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank
Contract Amount Pay	₩ 112,930
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 11 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan
Contract Amount Pay	₩ 112,930
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 12 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America
Contract Amount Pay	₩ 112,930
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 13 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Shinhan Bank	Shinhan Bank	Shinhan Bank	Shinhan Bank	Shinhan Bank	Shinhan Bank	Shinhan Bank
Contract Amount Pay	₩ 112,930
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30	1,129.30
Derivative, Term of Contract	2016~2022	2016~2022	2016~2022	2016~2022	2016~2022	2016~2022	2016~2022
Contract Interest rate Pay	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 14 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 111,770
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.89%	2.89%	2.89%	2.89%	2.89%	2.89%	2.89%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 15 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 111,770
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.87%	2.87%	2.87%	2.87%	2.87%	2.87%	2.87%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 16 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 111,770
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.89%	2.89%	2.89%	2.89%	2.89%	2.89%	2.89%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 17 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank
Contract Amount Pay	₩ 55,885
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70	1,117.70
Derivative, Term of Contract	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022	2012~2022
Contract Interest rate Pay	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%	2.79%
Contract Interest rate Receive	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%	3.00%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 18 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	DBS	DBS	DBS	DBS	DBS	DBS	DBS
Contract Amount Pay	₩ 108,140
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Contract Interest rate Receive	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 19 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	DBS	DBS	DBS	DBS	DBS	DBS	DBS
Contract Amount Pay	₩ 108,140
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.57%	2.57%	2.57%	2.57%	2.57%	2.57%	2.57%
Contract Interest rate Receive	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 20 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	DBS	DBS	DBS	DBS	DBS	DBS	DBS
Contract Amount Pay	₩ 108,140
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40	1,081.40
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.57%	2.57%	2.57%	2.57%	2.57%	2.57%	2.57%
Contract Interest rate Receive	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%	3M Libor+0.84%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 21 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 107,450
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.41%	3.41%	3.41%	3.41%	3.41%	3.41%	3.41%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 22 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 107,450
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.44%	3.44%	3.44%	3.44%	3.44%	3.44%	3.44%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 23 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan
Contract Amount Pay	₩ 107,450
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 24 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America	Bank of America
Contract Amount Pay	₩ 107,450
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50
Derivative, Term of Contract	2014~2018	2014~2018	2014~2018	2014~2018	2014~2018	2014~2018	2014~2018
Contract Interest rate Pay	3.09%	3.09%	3.09%	3.09%	3.09%	3.09%	3.09%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 25 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank
Contract Amount Pay	₩ 107,450
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50	1,074.50
Derivative, Term of Contract	2014~2018	2014~2018	2014~2018	2014~2018	2014~2018	2014~2018	2014~2018
Contract Interest rate Pay	3.09%	3.09%	3.09%	3.09%	3.09%	3.09%	3.09%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 26 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 105,260
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	2.48%	2.48%	2.48%	2.48%	2.48%	2.48%	2.48%
Contract Interest rate Receive	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 27 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 105,260
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	2.48%	2.48%	2.48%	2.48%	2.48%	2.48%	2.48%
Contract Interest rate Receive	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 28 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract Amount Pay	₩ 105,260
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60	1,052.60
Derivative, Term of Contract	2016~2019	2016~2019	2016~2019	2016~2019	2016~2019	2016~2019	2016~2019
Contract Interest rate Pay	2.48%	2.48%	2.48%	2.48%	2.48%	2.48%	2.48%
Contract Interest rate Receive	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 29 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 111,190
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90
Derivative, Term of Contract	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025
Contract Interest rate Pay	2.60%	2.60%	2.60%	2.60%	2.60%	2.60%	2.60%
Contract Interest rate Receive	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 30 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract Amount Pay	₩ 111,190
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90
Derivative, Term of Contract	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025
Contract Interest rate Pay	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%
Contract Interest rate Receive	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 31 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank
Contract Amount Pay	₩ 55,595
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90
Derivative, Term of Contract	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025
Contract Interest rate Pay	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%
Contract Interest rate Receive	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 32 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 55,595
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90	1,111.90
Derivative, Term of Contract	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025	2015~2025
Contract Interest rate Pay	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%
Contract Interest rate Receive	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%	3.25%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 33 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank
Contract Amount Pay	₩ 111,610
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10
Derivative, Term of Contract	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027
Contract Interest rate Pay	2.25%	2.25%	2.25%	2.25%	2.25%	2.25%	2.25%
Contract Interest rate Receive	3.13%	3.13%	3.13%	3.13%	3.13%	3.13%	3.13%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 34 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 111,610
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10
Derivative, Term of Contract	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027
Contract Interest rate Pay	2.31%	2.31%	2.31%	2.31%	2.31%	2.31%	2.31%
Contract Interest rate Receive	3.13%	3.13%	3.13%	3.13%	3.13%	3.13%	3.13%
Not Designated as Hedging Instrument [Member] | Currency swap contracts 35 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract Amount Pay	₩ 111,610
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10	1,116.10
Derivative, Term of Contract	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027	2017~2027
Contract Interest rate Pay	2.31%	2.31%	2.31%	2.31%	2.31%	2.31%	2.31%
Contract Interest rate Receive	3.13%	3.13%	3.13%	3.13%	3.13%	3.13%	3.13%
Designated as Hedging Instrument [Member] | Currency swap contracts 1 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank
Contract Amount Pay	₩ 54,570
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,091.40	1,091.40	1,091.40	1,091.40	1,091.40	1,091.40	1,091.40
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.90%	2.90%	2.90%	2.90%	2.90%	2.90%	2.90%
Contract Interest rate Receive	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%
Designated as Hedging Instrument [Member] | Currency swap contracts 2 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 54,570
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,091.40	1,091.40	1,091.40	1,091.40	1,091.40	1,091.40	1,091.40
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.90%	2.90%	2.90%	2.90%	2.90%	2.90%	2.90%
Contract Interest rate Receive	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%	3M Libor+1.01%
Designated as Hedging Instrument [Member] | Currency swap contracts 3 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse	Credit Suisse
Contract Amount Pay	₩ 111,410
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,114.10	1,114.10	1,114.10	1,114.10	1,114.10	1,114.10	1,114.10
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.22%	3.22%	3.22%	3.22%	3.22%	3.22%	3.22%
Contract Interest rate Receive	3M Libor+1.50%	3M Libor+1.50%	3M Libor+1.50%	3M Libor+1.50%	3M Libor+1.50%	3M Libor+1.50%	3M Libor+1.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 4 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 99,901
Contract Amount Receive | $					$ 100,000
Contract exchange rate	999.01	999.01	999.01	999.01	999.01	999.01	999.01
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	3.52%	3.52%	3.52%	3.52%	3.52%	3.52%	3.52%
Contract Interest rate Receive	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%
Designated as Hedging Instrument [Member] | Currency swap contracts 5 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 100,482
Contract Amount Receive | $					$ 100,000
Contract exchange rate	1,004.82	1,004.82	1,004.82	1,004.82	1,004.82	1,004.82	1,004.82
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%
Designated as Hedging Instrument [Member] | Currency swap contracts 6 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay | $			$ 117,250
Contract Amount Receive | $					$ 125,000
Contract exchange rate	0.94	0.94	0.94	0.94	0.94	0.94	0.94
Derivative, Term of Contract	2013~2020	2013~2020	2013~2020	2013~2020	2013~2020	2013~2020	2013~2020
Contract Interest rate Pay	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%
Contract Interest rate Receive	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%
Designated as Hedging Instrument [Member] | Currency swap contracts 7 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 126,032
Contract Amount Receive | $			$ 117,250
Contract exchange rate	1,074.90	1,074.90	1,074.90	1,074.90	1,074.90	1,074.90	1,074.90
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	3.55%	3.55%	3.55%	3.55%	3.55%	3.55%	3.55%
Contract Interest rate Receive	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%	3M Libor+1.25%
Designated as Hedging Instrument [Member] | Currency swap contracts 8 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract Amount Pay	₩ 114,580
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80
Derivative, Term of Contract	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020
Contract Interest rate Pay	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%
Contract Interest rate Receive	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%
Designated as Hedging Instrument [Member] | Currency swap contracts 9 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 114,580
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80
Derivative, Term of Contract	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020
Contract Interest rate Pay	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%
Contract Interest rate Receive	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%
Designated as Hedging Instrument [Member] | Currency swap contracts 10 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Export-import bank of Korea	Export-import bank of Korea	Export-import bank of Korea	Export-import bank of Korea	Export-import bank of Korea	Export-import bank of Korea	Export-import bank of Korea
Contract Amount Pay	₩ 114,580
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80	1,145.80
Derivative, Term of Contract	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020	2017~2020
Contract Interest rate Pay	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%
Contract Interest rate Receive	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%	2.38%
Designated as Hedging Instrument [Member] | Currency swap contracts 11 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan
Contract Amount Pay	₩ 107,190
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%
Contract Interest rate Receive	2.75%	2.75%	2.75%	2.75%	2.75%	2.75%	2.75%
Designated as Hedging Instrument [Member] | Currency swap contracts 12 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract Amount Pay	₩ 107,190
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%
Contract Interest rate Receive	2.75%	2.75%	2.75%	2.75%	2.75%	2.75%	2.75%
Designated as Hedging Instrument [Member] | Currency swap contracts 13 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank
Contract Amount Pay	₩ 107,190
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90	1,071.90
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%	3M Libor+3.25%
Contract Interest rate Receive	2.75%	2.75%	2.75%	2.75%	2.75%	2.75%	2.75%
Designated as Hedging Instrument [Member] | Currency swap contracts 14 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract Amount Pay	₩ 121,000
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,210	1,210	1,210	1,210	1,210	1,210	1,210
Derivative, Term of Contract	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021
Contract Interest rate Pay	2.15%	2.15%	2.15%	2.15%	2.15%	2.15%	2.15%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 15 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract Amount Pay	₩ 121,000
Contract Amount Receive | $			$ 100,000
Derivative, Term of Contract	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021
Contract Interest rate Pay	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 16 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas
Contract Amount Pay	₩ 121,000
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,210	1,210	1,210	1,210	1,210	1,210	1,210
Derivative, Term of Contract	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021	2016~2021
Contract Interest rate Pay	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%	3M Libor+2.10%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 17 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 52,457
Contract Amount Receive | €						€ 40,000
Contract exchange rate	1,311.42	1,311.42	1,311.42	1,311.42	1,311.42	1,311.42	1,311.42
Derivative, Term of Contract	2017~2037	2017~2037	2017~2037	2017~2037	2017~2037	2017~2037	2017~2037
Contract Interest rate Pay	2.60%	2.60%	2.60%	2.60%	2.60%	2.60%	2.60%
Contract Interest rate Receive	1.70%	1.70%	1.70%	1.70%	1.70%	1.70%	1.70%
Designated as Hedging Instrument [Member] | Currency swap contracts 18 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 59,423
Contract Amount Receive | kr							kr 450,000
Contract exchange rate	132.05	132.05	132.05	132.05	132.05	132.05	132.05
Derivative, Term of Contract	2017~2037	2017~2037	2017~2037	2017~2037	2017~2037	2017~2037	2017~2037
Contract Interest rate Pay	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%	2.62%
Contract Interest rate Receive	2.36%	2.36%	2.36%	2.36%	2.36%	2.36%	2.36%
Designated as Hedging Instrument [Member] | Currency swap contracts 19 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole
Contract Amount Pay	₩ 118,343
Contract Amount Receive | SFr				SFr 100,000
Contract exchange rate	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43
Derivative, Term of Contract	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019
Contract Interest rate Pay	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%
Contract Interest rate Receive	1.63%	1.63%	1.63%	1.63%	1.63%	1.63%	1.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 20 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract Amount Pay	₩ 59,172
Contract Amount Receive | SFr				SFr 50,000
Contract exchange rate	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43
Derivative, Term of Contract	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019
Contract Interest rate Pay	3.40%	3.40%	3.40%	3.40%	3.40%	3.40%	3.40%
Contract Interest rate Receive	1.63%	1.63%	1.63%	1.63%	1.63%	1.63%	1.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 21 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 59,172
Contract Amount Receive | SFr				SFr 50,000
Contract exchange rate	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43	1,183.43
Derivative, Term of Contract	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019	2013~2019
Contract Interest rate Pay	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%
Contract Interest rate Receive	1.63%	1.63%	1.63%	1.63%	1.63%	1.63%	1.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 22 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract Amount Pay	₩ 107,360
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.27%	3.27%	3.27%	3.27%	3.27%	3.27%	3.27%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 23 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole
Contract Amount Pay	₩ 107,360
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.34%	3.34%	3.34%	3.34%	3.34%	3.34%	3.34%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 24 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan	JP Morgan
Contract Amount Pay	₩ 161,040
Contract Amount Receive | $			$ 150,000
Contract exchange rate	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.34%	3.34%	3.34%	3.34%	3.34%	3.34%	3.34%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 25 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 161,040
Contract Amount Receive | $			$ 150,000
Contract exchange rate	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60	1,073.60
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.34%	3.34%	3.34%	3.34%	3.34%	3.34%	3.34%
Contract Interest rate Receive	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%	2.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 26 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 104,490
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	2.77%	2.77%	2.77%	2.77%	2.77%	2.77%	2.77%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 27 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole
Contract Amount Pay	₩ 104,490
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	2.77%	2.77%	2.77%	2.77%	2.77%	2.77%	2.77%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 28 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley	Morgan Stanley
Contract Amount Pay	₩ 104,490
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90	1,044.90
Derivative, Term of Contract	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019	2014~2019
Contract Interest rate Pay	2.70%	2.70%	2.70%	2.70%	2.70%	2.70%	2.70%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 29 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 81,188
Contract Amount Receive | $			$ 75,000
Contract exchange rate	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%
Contract Interest rate Receive	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 30 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole
Contract Amount Pay	₩ 81,188
Contract Amount Receive | $			$ 75,000
Contract exchange rate	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%
Contract Interest rate Receive	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 31 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank	Deutsche Bank
Contract Amount Pay	₩ 81,188
Contract Amount Receive | $			$ 75,000
Contract exchange rate	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%
Contract Interest rate Receive	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 32 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank	Citibank
Contract Amount Pay	₩ 81,188
Contract Amount Receive | $			$ 75,000
Contract exchange rate	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50	1,082.50
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%	2.65%
Contract Interest rate Receive	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%	1.88%
Designated as Hedging Instrument [Member] | Currency swap contracts 33 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale
Contract Amount Pay	₩ 106,190
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 34 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas
Contract Amount Pay	₩ 53,095
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 35 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 53,095
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90	1,061.90
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 36 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 106,030
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 37 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas
Contract Amount Pay	₩ 53,015
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 38 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 31,809
Contract Amount Receive | $			$ 30,000
Contract exchange rate	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 39 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale
Contract Amount Pay	₩ 21,206
Contract Amount Receive | $			$ 20,000
Contract exchange rate	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%	3.48%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 40 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 53,015
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 41 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 53,015
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30	1,060.30
Derivative, Term of Contract	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018	2013~2018
Contract Interest rate Pay	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%	3.47%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 42 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole	Credit Agricole
Contract Amount Pay	₩ 110,680
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.29%	2.29%	2.29%	2.29%	2.29%	2.29%	2.29%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 43 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale	Societe Generale
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.16%	2.16%	2.16%	2.16%	2.16%	2.16%	2.16%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 44 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.16%	2.16%	2.16%	2.16%	2.16%	2.16%	2.16%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 45 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 46 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered	Standard Chartered
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 47 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 48 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 49 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas	BNP Paribas
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 50 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC	HSBC
Contract Amount Pay	₩ 55,340
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80	1,106.80
Derivative, Term of Contract	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020	2014~2020
Contract Interest rate Pay	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%	2.21%
Contract Interest rate Receive	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%	2.50%
Designated as Hedging Instrument [Member] | Currency swap contracts 51 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank	KEB Hana Bank
Contract Amount Pay	₩ 226,600
Contract Amount Receive | $			$ 200,000
Contract exchange rate	1,133	1,133	1,133	1,133	1,133	1,133	1,133
Derivative, Term of Contract	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022
Contract Interest rate Pay	1.94%	1.94%	1.94%	1.94%	1.94%	1.94%	1.94%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 52 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank	Korea Development Bank
Contract Amount Pay	₩ 113,300
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,133	1,133	1,133	1,133	1,133	1,133	1,133
Derivative, Term of Contract	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022
Contract Interest rate Pay	1.94%	1.94%	1.94%	1.94%	1.94%	1.94%	1.94%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 53 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura	Nomura
Contract Amount Pay	₩ 113,300
Contract Amount Receive | $			$ 100,000
Contract exchange rate	1,133	1,133	1,133	1,133	1,133	1,133	1,133
Derivative, Term of Contract	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022
Contract Interest rate Pay	1.95%	1.95%	1.95%	1.95%	1.95%	1.95%	1.95%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 54 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank	Woori Bank
Contract Amount Pay	₩ 56,650
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,133	1,133	1,133	1,133	1,133	1,133	1,133
Derivative, Term of Contract	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022
Contract Interest rate Pay	1.95%	1.95%	1.95%	1.95%	1.95%	1.95%	1.95%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%
Designated as Hedging Instrument [Member] | Currency swap contracts 55 [Member]
Disclosure of Derivative Currency swap contract detail list [Line Items]
Counterparty	Kookmin Bank	Kookmin Bank	Kookmin Bank	Kookmin Bank	Kookmin Bank	Kookmin Bank	Kookmin Bank
Contract Amount Pay	₩ 56,650
Contract Amount Receive | $			$ 50,000
Contract exchange rate	1,133	1,133	1,133	1,133	1,133	1,133	1,133
Derivative, Term of Contract	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022	2017~2022
Contract Interest rate Pay	1.95%	1.95%	1.95%	1.95%	1.95%	1.95%	1.95%
Contract Interest rate Receive	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%	2.63%

Derivative Interest rate swap c

Derivative Interest rate swap contract List (Details) - 12 months ended Dec. 31, 2017 $ in Thousands, ₩ in Millions		KRW (₩)	USD ($)
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 1 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		JP Morgan
Derivative, Term of Contract		2013~2018
Contract Interest rate Pay		3.58%
Contract Interest rate Receive		3M CD+0.31%
Contract amount | ₩		₩ 150,000
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 2 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		Credit Suisse
Derivative, Term of Contract		2014~2018
Contract Interest rate Pay		2.98%
Contract Interest rate Receive		1Y CMT+0.31%
Contract amount | ₩		₩ 25,000
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 3 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		KEB Hana Bank
Derivative, Term of Contract		2017~2022
Contract Interest rate Pay		2.01%
Contract Interest rate Receive		3M CD+0.24%
Contract amount | ₩		₩ 100,000
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 4 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		KEB Hana Bank
Derivative, Term of Contract		2017~2022
Contract Interest rate Pay		2.06%
Contract Interest rate Receive		3M CD+0.27%
Contract amount | ₩		₩ 100,000
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 5 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty	[1]	Nomura
Derivative, Term of Contract	[1]	2017~2037
Contract Interest rate Pay	[1]	2.05%
Contract Interest rate Receive	[1]	3.08%
Contract amount | ₩	[1]	₩ 30,000
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 6 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		KEB Hana Bank
Derivative, Term of Contract		2017~2021
Contract Interest rate Pay		2.45%
Contract Interest rate Receive		3M CD+0.32%
Contract amount | ₩		₩ 200,000
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 7 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		Export-import bank of Korea
Derivative, Term of Contract		2015~2031
Contract Interest rate Pay		2.67%
Contract Interest rate Receive		6M USD Libor
Contract amount			$ 15,893
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 8 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		ING Bank
Derivative, Term of Contract		2015~2031
Contract Interest rate Pay		2.67%
Contract Interest rate Receive		6M USD Libor
Contract amount			7,861
Not Designated as Hedging Instrument [Member] | Interest rate swap contracts 9 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		BNP Paribas
Derivative, Term of Contract		2015~2031
Contract Interest rate Pay		2.67%
Contract Interest rate Receive		6M USD Libor
Contract amount			7,861
Designated as Hedging Instrument [Member] | Interest rate swap contracts 1 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		BNP Paribas
Derivative, Term of Contract		2009~2027
Contract Interest rate Pay		4.16%
Contract Interest rate Receive		6M USD Libor
Contract amount			92,120
Designated as Hedging Instrument [Member] | Interest rate swap contracts 2 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		KFW
Derivative, Term of Contract		2009~2027
Contract Interest rate Pay		4.16%
Contract Interest rate Receive		6M USD Libor
Contract amount			92,120
Designated as Hedging Instrument [Member] | Interest rate swap contracts 3 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		Credit Agricole
Derivative, Term of Contract		2016~2033
Contract Interest rate Pay		3.98% ~ 4.10%
Contract Interest rate Receive		6M USD Libor
Contract amount			96,297
Designated as Hedging Instrument [Member] | Interest rate swap contracts 4 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		SMBC
Derivative, Term of Contract		2016~2033
Contract Interest rate Pay		4.05% ~ 4.18%
Contract Interest rate Receive		6M USD Libor
Contract amount			125,927
Designated as Hedging Instrument [Member] | Interest rate swap contracts 5 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		Mizuho Bank
Derivative, Term of Contract		2016~2019
Contract Interest rate Pay		1.56%
Contract Interest rate Receive		1.35%
Contract amount			36,890
Designated as Hedging Instrument [Member] | Interest rate swap contracts 6 [Member]
Disclosure of Derivative Interest rate swap contract detail list [Line Items]
Counterparty		SMBC
Derivative, Term of Contract		2016~2019
Contract Interest rate Pay		1.56%
Contract Interest rate Receive		1.35%
Contract amount			$ 36,890
[1]	2.05% of the contract interest rate for paying is applied for five years from the date of issuance, and 3M CD + 0.10% is applied thereafter.

Other-Financial Assets (Details

Other-Financial Assets (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Financial Assets [Line Items]
Loans and receivables	₩ 955,378	₩ 881,486
Allowance for doubtful accounts	(8,948)	(4,532)
Present value discount	(40,789)	(42,747)
Long / short-term financial instruments [Abstract]
Time deposits	1,479,036	1,850,391
ABCP	210,600	484,400
CP	58,050	16,000
CD	10,000	60,443
RP	11,634	1,521
Others	475,194	283,171
Long / short-term financial instruments	2,244,514	2,695,926
Financial assets at fair value through profit or loss	111,512
Other financial assets	3,261,667	3,530,133
Other Current Assets [Member]
Other Financial Assets [Line Items]
Loans and receivables	244,309	198,133
Present value discount	(976)	(1,001)
Long / short-term financial instruments [Abstract]
Time deposits	1,479,034	1,820,391
ABCP	145,000	351,800
CP	58,050	16,000
CD	10,000	60,443
RP	10,000
Others		32,826
Long / short-term financial instruments	1,702,084	2,281,460
Other financial assets	1,945,417	2,478,592
Other Noncurrent Assets [Member]
Other Financial Assets [Line Items]
Loans and receivables	711,069	683,353
Allowance for doubtful accounts	(8,948)	(4,532)
Present value discount	(39,813)	(41,746)
Long / short-term financial instruments [Abstract]
Time deposits	2	30,000
ABCP	65,600	132,600
RP	1,634	1,521
Others	475,194	250,345
Long / short-term financial instruments	542,430	414,466
Financial assets at fair value through profit or loss	111,512
Other financial assets	₩ 1,316,250	₩ 1,051,541

Other-Financial Assets _ Loans

Other-Financial Assets : Loans and receivables (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Line Items]
Loans and receivables	₩ 905,641	₩ 834,207
Face value [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and receivables	955,378	881,486
Allowance for doubtful accounts [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and receivables	(8,948)	(4,532)
Present value discount [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and receivables	(40,789)	(42,747)
Short-term loans and receivables [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for tuition	32,787	28,027
Loans for housing	14,126	12,556
Fisheries loan	352	352
Other loans	196,068	156,197
Loans and receivables	243,333	197,132
Short-term loans and receivables [Member] | Face value [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for tuition	33,763	29,028
Loans for housing	14,126	12,556
Fisheries loan	352	352
Other loans	196,068	156,197
Loans and receivables	244,309	198,133
Short-term loans and receivables [Member] | Present value discount [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for tuition	(976)	(1,001)
Loans and receivables	(976)	(1,001)
Long-term loans and receivables [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for tuition	369,087	362,607
Loans for housing	140,452	125,850
Loans for related parties	85,633	86,717
Fisheries loan	863	1,159
Other loans	66,273	60,742
Loans and receivables	662,308	637,075
Long-term loans and receivables [Member] | Face value [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for tuition	408,803	404,200
Loans for housing	140,452	125,850
Loans for related parties	94,581	91,249
Fisheries loan	960	1,312
Other loans	66,273	60,742
Loans and receivables	711,069	683,353
Long-term loans and receivables [Member] | Allowance for doubtful accounts [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for related parties	(8,948)	(4,532)
Loans and receivables	(8,948)	(4,532)
Long-term loans and receivables [Member] | Present value discount [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans for tuition	(39,716)	(41,593)
Fisheries loan	(97)	(153)
Loans and receivables	₩ (39,813)	₩ (41,746)

Other-Financial Assets _ Change

Other-Financial Assets : Changes in the allowance for doubtful accounts of Loans and receivables (Details) ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)
Allowance for doubtful accounts [Abstract]
Beginning balance	₩ 4,532
Bad debt expense	2,465
Other	1,951
Ending balance	₩ 8,948

Inventories (Details)

Inventories (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory [Line Items]
Raw materials	₩ 3,526,006	₩ 3,181,388
Merchandise	107	20
Work-in-progress	137,681	118,640
Finished goods	71,406	57,659
Supplies	1,577,721	1,284,607
Inventories in transit	679,358	827,437
Other inventories	9,807	9,692
Total Inventories	6,002,086	5,479,443
Acquisition cost [Member]
Inventory [Line Items]
Raw materials	3,528,835	3,182,711
Merchandise	107	20
Work-in-progress	138,709	118,640
Finished goods	72,923	57,659
Supplies	1,581,661	1,289,160
Inventories in transit	679,358	827,437
Other inventories	9,807	9,692
Total Inventories	6,011,400	5,485,319
Valuation allowance [Member]
Inventory [Line Items]
Raw materials	(2,829)	(1,323)
Work-in-progress	(1,028)
Finished goods	(1,517)
Supplies	(3,940)	(4,553)
Total Inventories	₩ (9,314)	₩ (5,876)

Finance lease and operating lea

Finance lease and operating lease by lessor (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finance lease receivables of the Group as lessor [Line Items]
Minimum lease payment	₩ 1,829,172	₩ 2,169,352
Present value of minimum lease payment	862,621	972,874
Not Later Than 1 Year [Member]
Finance lease receivables of the Group as lessor [Line Items]
Minimum lease payment	49,542	55,708
Present value of minimum lease payment	13,067	12,225
1~5 Years [Member]
Finance lease receivables of the Group as lessor [Line Items]
Minimum lease payment	381,181	423,152
Present value of minimum lease payment	203,990	214,176
More than 5 years [Member]
Finance lease receivables of the Group as lessor [Line Items]
Minimum lease payment	1,398,449	1,690,492
Present value of minimum lease payment	₩ 645,564	₩ 746,473

Non-Financial Assets (Details)

Non-Financial Assets (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Other Current Assets [Member]
Non-Financial Assets [Line Items]
Advance payment		₩ 109,743	₩ 93,279
Prepaid Expense		251,715	228,142
Miscellaneous Non-Financial Assets [Abstract]
Tax refund receivables		89,762	30,959
Greenhouse gas emissions rights		135,211	145,105
Other quick assets	[1]	167,561	134,375
Miscellaneous Non-Financial Assets	[2]	392,534	310,439
Non-Financial Assets		753,992	631,860
Other Noncurrent Assets [Member]
Non-Financial Assets [Line Items]
Advance payment		43,872	71,238
Prepaid Expense		90,118	78,066
Miscellaneous Non-Financial Assets [Abstract]
Tax refund receivables		1,940	2,188
Other quick assets	[1]	110,888	30,297
Miscellaneous Non-Financial Assets	[2]	112,828	32,485
Non-Financial Assets		₩ 246,818	₩ 181,789
[1]	The Company has recognized ￦92,128 million of shares in Orano Expansion (formerly, AREVA NC Expansion) as non-current non-financial assets.
[2]	Details of others as of December 31, 2016 and 2017 are as follows:

Consolidated subsidiaries (Deta

Consolidated subsidiaries (Details)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Korea Hydro & Nuclear Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea South-East Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea Midland Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea Western Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea Southern Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea East-West Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Engineering & Construction Company [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities	[1]	Architectural engineering for utility plant and others	Architectural engineering for utility plant and others
Country of incorporation of subsidiary	[1]	KOREA	KOREA
Proportion of ownership interest in subsidiary	[1]	66.00%	66.00%
KEPCO Plant Service & Engineering [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Utility plant maintenance and others	Utility plant maintenance and others
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		51.00%	51.00%
KEPCO Nuclear Fuel [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Nuclear fuel	Nuclear fuel
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		96.00%	96.00%
KEPCO KDN [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Electric power information technology and others	Electric power information technology and others
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Garolim Tidal Power Plant [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities	[2]	Power generation	Power generation
Country of incorporation of subsidiary	[2]	KOREA	KOREA
Proportion of ownership interest in subsidiary	[2]	49.00%	49.00%
KEPCO International HongKong [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		HONG KONG	HONG KONG
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO International Philippines [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Gansu International [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		HONG KONG	HONG KONG
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Philippines Holdings [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Philippines Corporation [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Ilijan Corporation [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Utility plant rehabilitation and operation	Utility plant rehabilitation and operation
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		51.00%	51.00%
KEPCO Lebanon SARL [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		LEBANON	LEBANON
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Neimenggu International [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		HONG KONG	HONG KONG
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Shanxi International [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		HONG KONG	HONG KONG
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOMIPO Global Pte [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		SINGAPORE	SINGAPORE
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Canada Energy [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		CANADA	CANADA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Netherlands B.V. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		NETHERLANDS	NETHERLANDS
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOREA Imouraren Uranium Investment Corp. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		FRANCE	FRANCE
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Australia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSEP Australia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOMIPO Australia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOWEPO Australia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSPO Australia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Middle East Holding Company [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		BAHRAIN	BAHRAIN
Proportion of ownership interest in subsidiary		100.00%	100.00%
Qatrana Electric Power Company [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Construction and operation of utility plant	Construction and operation of utility plant
Country of incorporation of subsidiary		JORDAN	JORDAN
Proportion of ownership interest in subsidiary		80.00%	80.00%
KHNP Canada Energy [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		CANADA	CANADA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Bylong Australia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea Waterbury Uranium Limited Partnership [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		CANADA	CANADA
Proportion of ownership interest in subsidiary		80.00%	80.00%
Korea Electric Power Nigeria [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		NIGERIA	NIGERIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Holdings de Mexico [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		MEXICO	MEXICO
Proportion of ownership interest in subsidiary		100.00%	100.00%
KST Electric Power Company [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Construction and operation of utility plant	Construction and operation of utility plant
Country of incorporation of subsidiary		MEXICO	MEXICO
Proportion of ownership interest in subsidiary		56.00%	56.00%
KEPCO Energy Service Company [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		MEXICO	MEXICO
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Netherlands S3 B.V. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		NETHERLANDS	NETHERLANDS
Proportion of ownership interest in subsidiary		100.00%	100.00%
PT. KOMIPO Pembangkitan Jawa Bali [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		INDONESIA	INDONESIA
Proportion of ownership interest in subsidiary		51.00%	51.00%
PT. Cirebon Power Service [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities	[2]	Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary	[2]	INDONESIA	INDONESIA
Proportion of ownership interest in subsidiary	[2]	28.00%	28.00%
KOWEPO International Corporation [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSPO Jordan [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		JORDAN	JORDAN
Proportion of ownership interest in subsidiary		100.00%	100.00%
EWP Philippines Corporation [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		100.00%	100.00%
EWP America [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
EWP Renewable [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
DG Fairhaven Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
DG Whitefield [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Springfield Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KNF Canada Energy Limited [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		CANADA	CANADA
Proportion of ownership interest in subsidiary		96.00%	96.00%
PT KEPCO Resource Indonesia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		INDONESIA	INDONESIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
EWP Barbados 1 SRL [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		BARBADOS	BARBADOS
Proportion of ownership interest in subsidiary		100.00%	100.00%
California Power Holdings [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Gyeonggi Green Energy [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		62.00%	62.00%
PT. Tanggamus Electric Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		INDONESIA	INDONESIA
Proportion of ownership interest in subsidiary		53.00%	53.00%
Gyeongju Wind Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		70.00%	70.00%
KOMIPO America [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
EWPRC Biomass Holdings [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSEP USA INC. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		USA	USA
Proportion of ownership interest in subsidiary		100.00%	100.00%
PT. EWP Indonesia [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		INDONESIA	INDONESIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO Netherlands J3 B.V. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		NETHERLANDS	NETHERLANDS
Proportion of ownership interest in subsidiary		100.00%	100.00%
Korea Offshore Wind Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Global One Pioneer B.V. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		NETHERLANDS	NETHERLANDS
Proportion of ownership interest in subsidiary		100.00%	100.00%
Global Energy Pioneer B.V. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		NETHERLANDS	NETHERLANDS
Proportion of ownership interest in subsidiary		100.00%	100.00%
Mira Power Limited [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities	[3]	Power generation	Power generation
Country of incorporation of subsidiary	[3]	PAKISTAN	PAKISTAN
Proportion of ownership interest in subsidiary	[3]	76.00%	76.00%
KOSEP Material [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities	[4]	Recycling fly ashes	Recycling fly ashes
Country of incorporation of subsidiary	[4]	KOREA	KOREA
Proportion of ownership interest in subsidiary	[4]	86.00%	46.00%
Commerce and Industry Energy [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities	[5]	Power generation	Power generation
Country of incorporation of subsidiary	[5]	KOREA	KOREA
Proportion of ownership interest in subsidiary	[5]	59.00%	59.00%
KEPCO Singapore Holdings Pte. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		SINGAPORE	SINGAPORE
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOWEPO India Private Limited [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		INDIA	INDIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO KPS Philippines Corp. [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Utility plant maintenance and others	Utility plant maintenance and others
Country of incorporation of subsidiary		PHILIPPINES	PHILIPPINES
Proportion of ownership interest in subsidiary		51.00%	51.00%
KOSPO Chile SpA [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		CHILE	CHILE
Proportion of ownership interest in subsidiary		100.00%	100.00%
PT. KOWEPO Sumsel Operation and Maintenance Services [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Utility plant maintenance and others	Utility plant maintenance and others
Country of incorporation of subsidiary		INDONESIA	INDONESIA
Proportion of ownership interest in subsidiary		95.00%	95.00%
HeeMang Sunlight Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Fujeij Wind Power Company [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		JORDAN	JORDAN
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSPO Youngnam Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant	Operation of utility plant
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		50.00%	50.00%
HI Carbon Professional Private Special Asset Investment Trust 1 [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		97.00%	97.00%
Chitose Solar Power Plant [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		JAPAN	JAPAN
Proportion of ownership interest in subsidiary		80.00%	80.00%
KEPCO Energy Solution [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Energy service	Energy service
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
Solar School Plant [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation	Power generation
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSPO Power Services Limitada [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Utility plant maintenance and others	Utility plant maintenance and others
Country of incorporation of subsidiary		CHILE	CHILE
Proportion of ownership interest in subsidiary		65.00%	65.00%
Energy New Industry Specialized Investment Private Investment Trust [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company	Holding company
Country of incorporation of subsidiary		KOREA	KOREA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOEN Bylong [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOMIPO Bylong [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOWEPO Bylong [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOSPO Bylong [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
EWP Bylong [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Resources development	Resources development
Country of incorporation of subsidiary		AUSTRALIA	AUSTRALIA
Proportion of ownership interest in subsidiary		100.00%	100.00%
KOWEPO Lao International [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Utility plant maintenance and others	Utility plant maintenance and others
Country of incorporation of subsidiary		LAOS	LAOS
Proportion of ownership interest in subsidiary		100.00%	100.00%
KEPCO US [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		100.00%
Reason		Newly Established
KEPCO Alamosa [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		50.00%
Reason		Newly Established
Cogentrix Solar Services [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		50.00%
Reason		Newly Established
Solar Investments I [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		50.00%
Reason		Newly Established
Cogentrix of Alamosa [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		50.00%
Reason		Newly Established
KEPCO-LG CNS Mangilao Holdings [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		70.00%
Reason		Newly Established
Mangilao Investment [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		70.00%
Reason		Newly Established
KEPCO-LG CNS Mangilao Solar [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation
Country of incorporation of subsidiary		USA
Proportion of ownership interest in subsidiary		70.00%
Reason		Newly Established
Jeju Hanlim Offshore Wind Co [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Power generation
Country of incorporation of subsidiary		KOREA
Proportion of ownership interest in subsidiary		70.00%
Reason		Newly Established
PT. Siborpa Eco Power [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Operation of utility plant
Country of incorporation of subsidiary		INDONESIA
Proportion of ownership interest in subsidiary		65.00%
Reason		Newly Established
BSK E-New Industry Fund VII [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		KOREA
Proportion of ownership interest in subsidiary		81.00%
Reason		Newly Established
e-New Industry LB Fund 1 [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		KOREA
Proportion of ownership interest in subsidiary		76.00%
Reason		Newly Established
Songhyun e-New Industry Fund [Member]
Disclosure - Ownership of KEPCO and its material consolidated subsidiaries [Line Items]
Key operation activities		Holding company
Country of incorporation of subsidiary		KOREA
Proportion of ownership interest in subsidiary		80.00%
Reason		Newly Established
[1]	Considering treasury stocks, the effective percentage of ownership is 66.08%.
[2]	These subsidiaries are included in the consolidated financial statements as the Company obtained the majority of the voting power through the shareholders’ agreement.
[3]	As of reporting date, the annual reporting period of all subsidiaries is December 31, except for Mira Power Limited which is November 30.
[4]	The effective percentage of ownership has increased to 86.22% since Long Lasting Value exercised the put option to sell its investment to KOSEP during the year ended December 31, 2017.
[5]	The Company guarantees a certain return on investment related to Commerce and Industry Energy Co., Ltd. for the financial investors. The financial investors have a right to sell their shares to the Company which can be exercised 84 months after the date of investment. Accordingly, the purchase price including the return on investment is classified as a liability.

Summary of financial informatio

Summary of financial information of consolidated subsidiaries (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Korea Hydro & Nuclear Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		₩ 55,011,096		₩ 52,782,915
Total liabilities		29,252,816		27,366,938
Sales		9,415,751		11,168,579
Profit (loss) for the period		854,346		2,454,810
Korea South-East Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		9,879,577		9,773,778
Total liabilities		4,844,184		4,794,330
Sales		5,387,846		5,093,598
Profit (loss) for the period		130,371		531,061
Korea Midland Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		9,893,822		9,066,666
Total liabilities		6,148,173		5,416,336
Sales		4,167,009		3,719,981
Profit (loss) for the period		104,591		400,696
Korea Western Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		9,660,426		9,810,714
Total liabilities		5,739,534		5,866,916
Sales		4,199,079		4,169,712
Profit (loss) for the period		110,939		401,936
Korea Southern Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		9,648,741		9,806,023
Total liabilities		5,401,216		5,637,950
Sales		4,397,552		4,200,035
Profit (loss) for the period		98,817		426,337
Korea East-West Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		8,855,518		8,967,951
Total liabilities		4,204,187		4,488,911
Sales		4,644,330		4,210,898
Profit (loss) for the period		217,599		467,603
KEPCO Engineering & Construction Company [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		762,166		786,596
Total liabilities		305,134		364,676
Sales		490,193		506,012
Profit (loss) for the period		21,222		17,796
KEPCO Plant Service & Engineering [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		1,195,086		1,086,421
Total liabilities		294,689		301,490
Sales		1,232,113		1,214,304
Profit (loss) for the period		135,482		86,657
KEPCO Nuclear Fuel [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		792,187		713,230
Total liabilities		421,088		346,012
Sales		279,664		309,911
Profit (loss) for the period		4,557		33,115
KEPCO KDN [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		524,520		519,901
Total liabilities		155,715		205,869
Sales		619,470		588,160
Profit (loss) for the period		48,968		43,127
Garolim Tidal Power Plant [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		619		632
Total liabilities		345		346
Profit (loss) for the period		(12)		(24)
KEPCO International HongKong [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		153,529		173,138
Total liabilities		1		41
Profit (loss) for the period		4,380		4,532
KEPCO International Philippines [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		102,323		114,141
Total liabilities		886		1,468
Profit (loss) for the period		47,201		56,783
KEPCO Gansu International [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		11,567		17,928
Total liabilities		493		557
Profit (loss) for the period		(29)		(18)
KEPCO Philippines Holdings [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		127,922		125,100
Total liabilities		2,621		27
Profit (loss) for the period		43,218		13,517
KEPCO Philippines Corporation [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		6,293		13,704
Total liabilities		114		8,949
Profit (loss) for the period		2,098		(8,717)
KEPCO Ilijan Corporation [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		474,624		558,030
Total liabilities		57,801		58,449
Sales		109,183		116,667
Profit (loss) for the period		66,320		51,552
KEPCO Lebanon SARL [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		1,069		1,458
Total liabilities		9,281		10,312
Profit (loss) for the period		(219)		810
KEPCO Neimenggu International [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		165,937		186,636
Profit (loss) for the period		500		7,082
KEPCO Shanxi International [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		497,990		549,189
Total liabilities		193,309		218,047
Profit (loss) for the period		3,796		5,812
KOMIPO Global Pte [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		225,411		223,082
Total liabilities		1,497		1,095
Profit (loss) for the period		21,858		36,764
KEPCO Canada Energy [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		132		202
Total liabilities		22		24
Profit (loss) for the period		(32)		(27,216)
KEPCO Netherlands B.V. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		114,911		128,014
Total liabilities		49		35
Profit (loss) for the period		17,309		224
KOREA Imouraren Uranium Investment Corp. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		151,278		154,302
Total liabilities		131		764
Profit (loss) for the period		1,490		(68,417)
KEPCO Australia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		466,654		503,657
Total liabilities		569		1,545
Sales				3,670
Profit (loss) for the period		(568)		(19,006)
KOSEP Australia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		27,076		25,174
Total liabilities		333		521
Sales		12,096		5,357
Profit (loss) for the period		1,601		4,028
KOMIPO Australia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		31,441		25,413
Total liabilities		4,691		10
Sales		12,096		5,388
Profit (loss) for the period		1,133		4,023
KOWEPO Australia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		31,586		25,550
Total liabilities		4,691		10
Sales		12,096		5,357
Profit (loss) for the period		1,232		4,012
KOSPO Australia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		29,472		25,625
Total liabilities		4,221		10
Sales		12,096		5,357
Profit (loss) for the period		(2,759)		4,033
KEPCO Middle East Holding Company [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		95,812		128,846
Total liabilities		90,842		125,008
Profit (loss) for the period		2,913		6,840
Qatrana Electric Power Company [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		460,206		546,123
Total liabilities		327,401		417,800
Sales		18,892		18,866
Profit (loss) for the period		23,310		19,601
KHNP Canada Energy [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		51,994		54,374
Total liabilities		31		46
Profit (loss) for the period		(92)		(6,304)
KEPCO Bylong Australia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		242,364		220,721
Total liabilities		277,549		277,358
Profit (loss) for the period		20,271		(2,357)
Korea Waterbury Uranium Limited Partnership [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		20,886		20,882
Total liabilities		136		149
Profit (loss) for the period		(59)		2,348
Korea Electric Power Nigeria [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		238		696
Total liabilities		76		493
Sales		2,164		9,794
Profit (loss) for the period		29		35
KEPCO Holdings de Mexico [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		235		262
Total liabilities		30		19
Profit (loss) for the period		(20)		251
KST Electric Power Company [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		546,242		596,823
Total liabilities		478,230		539,459
Sales		120,126		146,295
Profit (loss) for the period		16,154		17,322
KEPCO Energy Service Company [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		1,793		1,309
Total liabilities		451		310
Sales		6,773		5,337
Profit (loss) for the period		976		580
KEPCO Netherlands S3 B.V. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		46,642		55,609
Total liabilities		53		54
Profit (loss) for the period		2,382		3,731
PT. KOMIPO Pembangkitan Jawa Bali [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		11,261		16,246
Total liabilities		4,769		4,549
Sales		20,956		21,632
Profit (loss) for the period		4,666		8,989
PT. Cirebon Power Service [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		2,808		3,456
Total liabilities		155		1,228
Sales		7,439		7,463
Profit (loss) for the period		592		301
KOWEPO International Corporation [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total liabilities		8
Profit (loss) for the period		(2)
KOSPO Jordan [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		24,077		11,524
Total liabilities		13,594		687
Sales		7,331		7,321
Profit (loss) for the period		953		317
EWP Philippines Corporation [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		1,708		1,966
Total liabilities		836		955
Profit (loss) for the period		(17)		(41)
EWP America [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		79,854	[1]	104,809	[2]
Total liabilities		67,308	[1]	80,252	[2]
Sales		23,543	[1]	33,616	[2]
Profit (loss) for the period		(9,737)	[1]	(8,704)	[2]
KNF Canada Energy Limited [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		1,884		1,967
Total liabilities		31		20
Profit (loss) for the period		(43)		(46)
PT KEPCO Resource Indonesia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		491		913
Total liabilities				18
Profit (loss) for the period		(311)		(341)
EWP Barbados 1 SRL [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		235,096		267,859
Total liabilities		450		425
Sales				1,656
Profit (loss) for the period		(2,585)		(902)
Gyeonggi Green Energy [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		282,408		301,126
Total liabilities		199,160		221,078
Sales		95,192		108,557
Profit (loss) for the period		3,203		19,211
PT. Tanggamus Electric Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		179,317		184,861
Total liabilities		160,144		167,641
Sales		34,281		40,903
Profit (loss) for the period		4,640		2,041
Gyeongju Wind Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		112,279		76,569
Total liabilities		82,124		49,293
Sales		7,219		6,413
Profit (loss) for the period		2,400		1,269
KOMIPO America [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		10,505		11,518
Total liabilities		521		2,432
Profit (loss) for the period		2,071		(2,240)
KOSEP USA INC. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		184		159
Total liabilities		9,065		39,028
Sales				3,791
Profit (loss) for the period		26,997		(72,817)
PT. EWP Indonesia [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		2,035		2,154
Total liabilities		23		50
Profit (loss) for the period		1,916		1,088
KEPCO Netherlands J3 B.V. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		122,612		125,337
Total liabilities		76		68
Profit (loss) for the period		12,115		12,433
Korea Offshore Wind Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		190,195		37,826
Total liabilities		1,985		2,048
Profit (loss) for the period		(6,997)		(4,960)
Global One Pioneer B.V. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		151		161
Total liabilities		38		22
Profit (loss) for the period		(80)		(54)
Global Energy Pioneer B.V. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		309		338
Total liabilities		41		22
Profit (loss) for the period		(87)		(59)
Mira Power Limited [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		208,150		178,141
Total liabilities		163,198		133,730
Profit (loss) for the period		737		(954)
KOSEP Material [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		2,751		2,398
Total liabilities		1,448		1,497
Sales		3,128		3,232
Profit (loss) for the period		320		(901)
Commerce and Industry Energy [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		99,129		99,432
Total liabilities		87,926		87,316
Sales		30,577		28,375
Profit (loss) for the period		(749)		(536)
KEPCO Singapore Holdings Pte. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		3,265		2,568
Total liabilities		4		13
Profit (loss) for the period		(24)		(33)
KOWEPO India Private Limited [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		781		879
Profit (loss) for the period		(46)		1
KEPCO KPS Philippines Corp. [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		6,636		7,897
Total liabilities		235		1,213
Sales		6,840		12,843
Profit (loss) for the period		555		2,060
KOSPO Chile SpA [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		133,570		6,656
Total liabilities		50,109		4,787
Profit (loss) for the period		1,066		125
PT. KOWEPO Sumsel Operation and Maintenance Services [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		1,350		1,439
Total liabilities		279		700
Sales		7,651		6,165
Profit (loss) for the period		659		(96)
HeeMang Sunlight Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		6,876		7,102
Total liabilities		3,395		3,391
Sales		105		12
Profit (loss) for the period		(229)		(308)
Fujeij Wind Power Company [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		165,636		47,935
Total liabilities		156,099		46,636
Profit (loss) for the period		8,836		(873)
KOSPO Youngnam Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		412,785		284,368
Total liabilities		333,302		205,680
Sales		68,973
Profit (loss) for the period		939		(931)
HI Carbon Professional Private Special Asset Investment Trust 1 [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		3,002		3,002
Profit (loss) for the period		12		9
Chitose Solar Power Plant [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		136,098		49,728
Total liabilities		121,622		38,806
Sales		7,083
Profit (loss) for the period		4,100		(811)
KEPCO Energy Solution [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		313,401		299,933
Total liabilities		12,376		233
Sales		5,544
Profit (loss) for the period		1,325		(300)
Solar School Plant [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		201,482		200,268
Total liabilities		599		259
Sales		67		1
Profit (loss) for the period		874		9
KOSPO Power Services Limitada [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		3,901		4,385
Total liabilities		887		1,262
Sales		11,067		7,300
Profit (loss) for the period		666		2,963
Energy New Industry Specialized Investment Private Investment Trust [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		506,207	[3]	501,275
Total liabilities		2,118	[3]	33
Profit (loss) for the period		52	[3]	(7)
KOEN Bylong [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		5,875		6,135
KOMIPO Bylong [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		5,875		6,135
KOWEPO Bylong [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		5,875		6,135
KOSPO Bylong [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		5,875		6,135
EWP Bylong [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		5,875		6,135
KOWEPO Lao International [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		3,259		218
Total liabilities		1,452		181
Sales		3,624
Profit (loss) for the period		1,881		₩ (108)
KEPCO US [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		16,913
KEPCO Alamosa [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		33,144
Total liabilities		492
Profit (loss) for the period		(218)
Cogentrix Solar Services [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets	[4]	84,458
Total liabilities	[4]	53,116
Sales	[4]	8,958
Profit (loss) for the period	[4]	(112)
KEPCO-LG CNS Mangilao Holdings [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		24,131
Total liabilities		24,395
Profit (loss) for the period		(278)
Mangilao Investment [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		24,131
KEPCO-LG CNS Mangilao Solar [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		24,002
Total liabilities		134
Profit (loss) for the period		(278)
Jeju Hanlim Offshore Wind Co [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		36
PT. Siborpa Eco Power [Member]
Disclosure - Summary of financial information of consolidated subsidiaries [Line Items]
Total assets		11,562
Total liabilities		214
Profit (loss) for the period		₩ (518)
[1]	Financial information of EWP America Inc. includes that of six other subsidiaries, EWP Renewable Corporation, DG Fairhaven Power, LLC, DG Whitefield, LLC, Springfield Power, LLC, California Power Holdings, LLC, and EWPRC Biomass Holdings, LLC.
[2]	Financial information of EWP America Inc. includes that of six other subsidiaries, EWP Renewable Co., DG Fairhaven Power, LLC, DG Whitefield, LLC, Springfield Power, LLC, California Power Holdings, LLC, and EWPRC Biomass Holdings, LLC.
[3]	Financial information of Energy New Industry Specialized Investment Private Investment Trust includes that of three other subsidiaries, BSK E-New Industry Fund VII, e-New Industry LB Fund 1 and Songhyun e-New Industry Fund.
[4]	Financial information of Cogentrix Solar Services, LLC includes that of two other subsidiaries, Solar Investments I, LLC and Cogentrix of Alamosa, LLC.

Details of non-controlling inte

Details of non-controlling interest prior to intra-group eliminations (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Subsidiaries [Member]
Disclosure - Details of non-controlling interest prior to intra-group eliminations [Line Items]
Current assets of subsidiaries	₩ 2,311,226	₩ 2,190,745
Non-current assets of subsidiaries	3,978,658	3,831,694
Current liabilities of subsidiaries	(916,288)	(867,716)
Non-current liabilities of subsidiaries	(2,150,581)	(2,074,333)
Net assets of subsidiaries	3,223,015	3,080,390
Book value of non-controlling interest	1,412,707	1,456,618
Sales of subsidiaries	2,550,576	2,511,444
Profit for the period of subsidiaries	289,443	258,175
Profit for the period attributable to non-controlling interest of subsidiaries	126,529	100,467
Cash flows from operating activities of subsidiaries	375,934	326,620
Cash flows from investing activities of subsidiaries	(616,659)	(295,540)
Cash flows from financing activities before dividends to non-controlling interest of subsidiaries	223,880	779,455
Dividends to non-controlling interest of subsidiaries	(86,108)	(116,437)
Effect of exchange rate fluctuation of subsidiaries	(33,006)	8,018
Net increase (decrease) of cash and cash equivalents of subsidiaries	₩ (135,959)	₩ 702,116
KEPCO Ilijan Corporation [Member]
Disclosure - Details of non-controlling interest prior to intra-group eliminations [Line Items]
Percentage of noncontrolling interest	49.00%	49.00%
Current assets of subsidiaries	₩ 160,588	₩ 154,758
Non-current assets of subsidiaries	314,036	403,272
Current liabilities of subsidiaries	(21,546)	(19,256)
Non-current liabilities of subsidiaries	(36,255)	(39,193)
Net assets of subsidiaries	416,823	499,581
Book value of non-controlling interest	204,243	244,794
Sales of subsidiaries	109,183	116,667
Profit for the period of subsidiaries	66,320	51,552
Profit for the period attributable to non-controlling interest of subsidiaries	32,497	25,260
Cash flows from operating activities of subsidiaries	123,534	102,546
Cash flows from investing activities of subsidiaries	(5,276)	(117)
Cash flows from financing activities before dividends to non-controlling interest of subsidiaries	(44,442)	(56,863)
Dividends to non-controlling interest of subsidiaries	(48,855)	(55,705)
Effect of exchange rate fluctuation of subsidiaries	(7,432)	1,529
Net increase (decrease) of cash and cash equivalents of subsidiaries	₩ 17,529	₩ (8,610)
KEPCO Plant Service & Engineering [Member]
Disclosure - Details of non-controlling interest prior to intra-group eliminations [Line Items]
Percentage of noncontrolling interest	49.00%	49.00%
Current assets of subsidiaries	₩ 623,934	₩ 553,924
Non-current assets of subsidiaries	571,152	532,497
Current liabilities of subsidiaries	(278,562)	(264,506)
Non-current liabilities of subsidiaries	(16,127)	(36,984)
Net assets of subsidiaries	900,397	784,931
Book value of non-controlling interest	441,194	384,616
Sales of subsidiaries	1,232,113	1,214,304
Profit for the period of subsidiaries	135,482	86,657
Profit for the period attributable to non-controlling interest of subsidiaries	66,386	42,462
Cash flows from operating activities of subsidiaries	129,801	121,240
Cash flows from investing activities of subsidiaries	(193,408)	79,807
Cash flows from financing activities before dividends to non-controlling interest of subsidiaries	(15,606)	(39,911)
Dividends to non-controlling interest of subsidiaries	(14,994)	(36,139)
Effect of exchange rate fluctuation of subsidiaries	(1,267)	127
Net increase (decrease) of cash and cash equivalents of subsidiaries	₩ (95,474)	₩ 125,124
KEPCO Engineering & Construction Company [Member]
Disclosure - Details of non-controlling interest prior to intra-group eliminations [Line Items]
Percentage of noncontrolling interest	33.92%	33.92%
Current assets of subsidiaries	₩ 257,529	₩ 270,553
Non-current assets of subsidiaries	504,637	516,043
Current liabilities of subsidiaries	(221,860)	(286,444)
Non-current liabilities of subsidiaries	(83,274)	(78,232)
Net assets of subsidiaries	457,032	421,920
Book value of non-controlling interest	155,025	143,115
Sales of subsidiaries	490,193	506,012
Profit for the period of subsidiaries	21,222	17,796
Profit for the period attributable to non-controlling interest of subsidiaries	7,199	6,036
Cash flows from operating activities of subsidiaries	62,578	18,748
Cash flows from investing activities of subsidiaries	(8,622)	(7,556)
Cash flows from financing activities before dividends to non-controlling interest of subsidiaries	(55,504)	(1,634)
Dividends to non-controlling interest of subsidiaries	(1,419)	(2,539)
Effect of exchange rate fluctuation of subsidiaries	(101)	(854)
Net increase (decrease) of cash and cash equivalents of subsidiaries	(3,068)	6,165
Others [Member]
Disclosure - Details of non-controlling interest prior to intra-group eliminations [Line Items]
Current assets of subsidiaries	1,269,175	1,211,510
Non-current assets of subsidiaries	2,588,833	2,379,882
Current liabilities of subsidiaries	(394,320)	(297,510)
Non-current liabilities of subsidiaries	(2,014,925)	(1,919,924)
Net assets of subsidiaries	1,448,763	1,373,958
Book value of non-controlling interest	612,245	684,093
Sales of subsidiaries	719,087	674,461
Profit for the period of subsidiaries	66,419	102,170
Profit for the period attributable to non-controlling interest of subsidiaries	20,447	26,709
Cash flows from operating activities of subsidiaries	60,021	84,086
Cash flows from investing activities of subsidiaries	(409,353)	(367,674)
Cash flows from financing activities before dividends to non-controlling interest of subsidiaries	339,432	877,863
Dividends to non-controlling interest of subsidiaries	(20,840)	(22,054)
Effect of exchange rate fluctuation of subsidiaries	(24,206)	7,216
Net increase (decrease) of cash and cash equivalents of subsidiaries	₩ (54,946)	₩ 579,437

Gain (loss) from Disposals of s

Gain (loss) from Disposals of subsidiaries (Details) ₩ in Millions	12 Months Ended
	Dec. 31, 2016KRW (₩)
gain (loss) of Disposaled subsidiaries [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	₩ 0
Fair value of Disposaled subsidiaries [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	35,046
Consideration received in cash [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	898
Net assets transferred due to dissolution [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	34,148
Carrying value of Disposaled subsidiaries [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	35,046
Cash and Cash Equivalents [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	898
Total current financial assets [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	81
Financial assets available-for-sale [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	34,089
Current financial liabilities [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	(22)
Non-controlling interests [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	0
Realization of unrealized gain [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	0
Other comprehensive income [Member]
Disclosure of Gain (loss) of Disposaled subsidiaries [Line Items]
gain (loss) of Disposaled subsidiaries	₩ 0

Cashflows From Disposaled subsi

Cashflows From Disposaled subsidiaries (Details) ₩ in Millions	12 Months Ended
	Dec. 31, 2016KRW (₩)
Net cash flow of Disposaled subsidiaries [Member]
Disclosure of Cashflows From Disposaled subsidiaries [Line Items]
Net cash flow of Disposaled subsidiaries	₩ 0
Consideration received in cash [Member]
Disclosure of Cashflows From Disposaled subsidiaries [Line Items]
Net cash flow of Disposaled subsidiaries	898
Less: cash held by disposed subsidiaries [Member]
Disclosure of Cashflows From Disposaled subsidiaries [Line Items]
Net cash flow of Disposaled subsidiaries	₩ (898)

Cash dividends received from su

Cash dividends received from subsidiaries (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsidiaries [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	₩ 1,088,210	₩ 1,150,208	₩ 833,195
Korea Hydro & Nuclear Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	543,072	635,200	446,399
Korea South-East Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	106,546	124,169	57,485
Korea Midland Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	54,305	23,073	16,580
Korea Western Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	66,992	36,238	22,749
Korea Southern Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	60,630	17,849	10,272
Korea East-West Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	94,430	67,906	25,280
KEPCO Engineering & Construction Company [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	2,765	5,069	14,574
KEPCO Plant Service & Engineering [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	15,607	39,911	40,584
KEPCO Nuclear Fuel [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	3,231	3,411	6,280
KEPCO KDN [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	4,352	3,392	4,046
KEPCO International HongKong [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	4,304	9,107	25,826
KEPCO International Philippines [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	44,906	61,862	32,891
KEPCO Ilijan Corporation [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	50,849	57,979	38,128
KEPCO Philippines Holdings [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	26,023	17,747	19,221
KEPCO Neimenggu International [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries		10,735	25,338
KOMIPO Global Pte [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries		10,432
Qatrana Electric Power Company [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	5,939	8,331	16,857
KOSPO Jordan [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries		1,095
KEPCO Energy Service Company [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries		294
EWP Philippines Corporation [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries			5,586
KEPCO Netherlands S3 B.V. [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries			1,382
PT. KOMIPO Pembangkitan Jawa Bali [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	3,188	3,222	3,169
KEPCO Netherlands J3 B.V. [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries		12,507	19,254
Gyeongju Wind Power [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries		₩ 679	₩ 1,294
Energy New Industry Specialized Investment Private Investment Trust [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	291
HI Carbon Professional Private Special Asset Investment Trust 1 [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	11
KOSPO Power Services Limitada [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	425
Cogentrix Solar Services [Member]
Disclosure of Cash dividends received from subsidiaries [Line Items]
Cash dividends received from subsidiaries	₩ 344

Investments in Associates (Deta

Investments in Associates (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Daegu Green Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities				Power generation
Location				KOREA
Percentage of ownership				29.00%
Book value [Abstract]
Beginning balance				₩ 80,267
Acquisition				3,347
Disposal				(34,422)
Share of income (loss)				(1,814)
Other comprehensive income (loss)				148
Others (book value)				₩ (47,526)
Korea Gas Corporation [Member]
Disclosure of associates [Line Items]
Key operation activities	[1]	Importing and wholesaling LNG		Importing and wholesaling LNG
Location	[1]	KOREA		KOREA
Percentage of ownership	[1]	20.47%		20.47%
Acquisition cost	[1]	₩ 94,500		₩ 94,500
Book value [Abstract]
Beginning balance		1,933,877	[1]	2,102,813
Dividends received				(3,213)
Share of income (loss)		(242,232)		(146,308)
Other comprehensive income (loss)		(72,648)		(14,551)
Others (book value)		(129)		(4,864)
Ending balance	[1]	1,618,868		1,933,877
The fair value of associates		804,195		915,705
Share in net assets		1,755,887		2,024,665
Total assets		37,139,439		39,927,836
Total liabilities		28,999,025		30,541,350
Net assets		8,140,414		9,386,486
Others (consolidated FS)		(137,019)		(90,788)
Sales of Associates		22,172,305		21,108,116
Profit (loss) for the period of Associates		₩ (1,205,110)		₩ (673,558)
Korea Electric Power Industrial Development Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Electricity metering and others		Electricity metering and others
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 4,727		₩ 4,727
Book value [Abstract]
Beginning balance		20,475		18,994
Dividends received		(2,061)		(1,598)
Share of income (loss)		3,428		4,491
Other comprehensive income (loss)		102
Others (book value)		(106)		(1,412)
Ending balance		21,838		20,475
The fair value of associates		38,667		45,474
Share in net assets		21,838		20,475
Total assets		155,033		144,346
Total liabilities		79,730		73,742
Net assets		75,303		70,604
Sales of Associates		334,547		304,067
Profit (loss) for the period of Associates		₩ 16,126		₩ 17,187
YTN Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Broadcasting		Broadcasting
Location		KOREA		KOREA
Percentage of ownership		21.43%		21.43%
Acquisition cost		₩ 59,000		₩ 59,000
Book value [Abstract]
Beginning balance		38,156		38,365
Dividends received		(135)
Share of income (loss)		1,095		(227)
Other comprehensive income (loss)		929		32
Others (book value)		561		(14)
Ending balance		40,606		38,156
The fair value of associates		18,855		22,320
Share in net assets		40,624		38,191
Total assets		298,122		304,536
Total liabilities		108,554		126,324
Net assets		189,568		178,212
Intercompany transaction		(18)		(30)
Others (consolidated FS)				(5)
Sales of Associates		131,080		130,690
Profit (loss) for the period of Associates		₩ 3,638		₩ 2,051
Cheongna Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Generating and distributing vapor and hot/cold water		Generating and distributing vapor and hot/cold water
Location		KOREA		KOREA
Percentage of ownership		43.90%		43.90%
Acquisition cost		₩ 48,353		₩ 48,353
Book value [Abstract]
Beginning balance		12,373		19,490
Share of income (loss)		(4,036)		(7,117)
Ending balance		8,337		12,373
Share in net assets		5,893		9,933
Total assets		461,958		469,843
Total liabilities		448,535		447,216
Net assets		13,423		22,627
Investment differential		2,584		2,584
Intercompany transaction		(140)		(144)
Sales of Associates		56,533		46,484
Profit (loss) for the period of Associates		₩ (9,203)		₩ (16,127)
Gangwon Wind Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[2]	Power generation		Power generation
Location	[2]	KOREA		KOREA
Percentage of ownership	[2]	15.00%		15.00%
Acquisition cost	[2]	₩ 5,725		₩ 5,725
Book value [Abstract]
Beginning balance		13,069	[2]	12,890
Dividends received		(852)		(1,136)
Share of income (loss)		1,638		1,270
Other comprehensive income (loss)				45
Ending balance	[2]	13,855		13,069
Share in net assets		13,806		13,020
Total assets		94,281		102,550
Total liabilities		2,243		15,753
Net assets		92,038		86,797
Others (consolidated FS)		49		49
Sales of Associates		25,963		22,774
Profit (loss) for the period of Associates		₩ 11,121		₩ 8,133
Hyundai Green Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 88,885		₩ 88,885
Book value [Abstract]
Beginning balance		115,998		113,664
Dividends received		(8,889)		(8,888)
Share of income (loss)		7,697		11,222
Ending balance		114,806		115,998
Share in net assets		114,806		115,998
Total assets		1,150,729		1,151,975
Total liabilities		754,846		751,981
Net assets		395,883		399,994
Sales of Associates		477,373		469,547
Profit (loss) for the period of Associates		₩ 26,543		₩ 38,743
Shareholders’ agreements that may cause future economic resource or cash outflows		As of December 31, 2017, Hyundai Green Power Co., Ltd., an associate of the Company, which engages in the byproduct gas power generating business, entered into a project financing agreement with a limit of ￦919.2 billion with Korea Development Bank and others. At a certain period in the future, the Company has an appraisal right against the financial investors (Korea Development Bank and others) and also has an obligation to sell its shares when claimed by the financial investors. At a certain period in the future, the Company has an appraisal right against Hyundai Steel Company and a third party designated by Hyundai Steel Company (collectively, “Hyundai Steel Company”), the operating investor of Hyundai Green Power Co., Ltd., according to the conditions of the agreement and also has an obligation to sell its shares when claimed by Hyundai Steel Company.
Korea Power Exchange [Member]
Disclosure of associates [Line Items]
Key operation activities		Management of power market and others	[3]	Management of power market and others	[4]
Location		KOREA	[3]	KOREA	[4]
Percentage of ownership		100.00%	[3]	100.00%	[4]
Acquisition cost		₩ 127,839	[3]	₩ 127,839	[4]
Book value [Abstract]
Beginning balance		223,238	[4]	208,735
Share of income (loss)		8,831		15,847
Others (book value)		5,562		(1,344)
Ending balance		237,631	[3]	223,238	[4]
Share in net assets		237,631		223,238
Total assets		263,499		255,533
Total liabilities		25,868		32,295
Net assets		237,631		223,238
Sales of Associates		105,107		101,222
Profit (loss) for the period of Associates		₩ 8,831		₩ 15,087
AMEC Partners Korea Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[5]	Resources development		Resources development
Location	[5]	KOREA		KOREA
Percentage of ownership	[5]	19.00%		19.00%
Acquisition cost	[5]	₩ 707		₩ 707
Book value [Abstract]
Beginning balance		225	[5]	230
Share of income (loss)		(10)		(5)
Ending balance	[5]	215		225
Share in net assets		215		225
Total assets		1,135		1,216
Total liabilities		4		32
Net assets		1,131		1,184
Sales of Associates		1		103
Profit (loss) for the period of Associates		₩ (53)		₩ (25)
Hyundai Energy [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation	[6]	Power generation	[7]
Location		KOREA	[6]	KOREA	[7]
Percentage of ownership		30.66%	[6]	30.66%	[7]
Acquisition cost		₩ 71,070	[6]	₩ 71,070	[7]
Book value [Abstract]
Beginning balance		1,031	[7]	6,990
Share of income (loss)		(3,498)		(21,163)
Others (book value)		2,467		15,204
Ending balance	[7]			1,031
Share in net assets		(16,921)		3,136
Total assets		474,939		505,979
Total liabilities		511,486		499,205
Net assets		(36,547)		6,774
Intercompany transaction		(1,037)		(1,079)
Others (consolidated FS)		17,958		(1,026)
Sales of Associates		92,992		61,813
Profit (loss) for the period of Associates		₩ (43,317)		₩ (45,800)
Shareholders’ agreements that may cause future economic resource or cash outflows		The Company had placed guarantees for a fixed return on the investment to NH Power II Co., Ltd. and National Agricultural Cooperative Federation (“NACF”) and had obtained the rights to acquire the investment securities in return preferentially. In addition, NH Power II Co., Ltd. and NACF have a right, which can be exercised for 30 days starting from 2 months to 1 month prior to 17 years after the termination date of the contract to sell their shares to the Company.
Ecollite Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Artificial light-weight aggregate		Artificial light-weight aggregate
Location		KOREA		KOREA
Percentage of ownership		36.10%		36.10%
Acquisition cost		₩ 1,516		₩ 1,516
Book value [Abstract]
Share in net assets		614		657
Total assets		2,052		2,157
Total liabilities		352		336
Net assets		1,700		1,821
Others (consolidated FS)		(614)		(657)
Profit (loss) for the period of Associates		₩ (121)		₩ (105)
Taebaek Wind Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		25.00%		25.00%
Acquisition cost		₩ 3,810		₩ 3,810
Book value [Abstract]
Beginning balance		4,750		4,956
Share of income (loss)		569		(206)
Ending balance		5,319		4,750
Share in net assets		5,319		4,750
Total assets		39,227		43,162
Total liabilities		17,953		24,162
Net assets		21,274		19,000
Sales of Associates		7,056		5,741
Profit (loss) for the period of Associates		₩ 2,312		₩ (2,796)
Shareholders’ agreements that may cause future economic resource or cash outflows		In case non-controlling shareholders decide to dispose of their shares in Taebaek Wind Power Co., Ltd. after the warrant period of defect repair for wind power generator has expired, the Company acquires those shares at fair value. The acquisition is to be made after the conditions of the acquisition are discussed among the parties involved, with consideration of various factors such as financial status and business situation.
Significant restrictions on its abilities		Financial institutions can reject or defer an approval with regard to the request for fund executions on subordinated loans of shareholders in order to pay senior loans based on the loan agreement.
Taeback Guinemi Wind Power Co., Ltd. (formerly, Muju Wind Power Co., Ltd.) [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		25.00%		25.00%
Acquisition cost		₩ 3,420		₩ 3,420
Book value [Abstract]
Beginning balance		3,131		2,587
Acquisition				570
Share of income (loss)		(42)		(26)
Ending balance		3,089		3,131
Share in net assets		3,089		3,131
Total assets		12,369		12,523
Total liabilities		12		1
Net assets		12,357		12,522
Profit (loss) for the period of Associates		₩ (140)		₩ (106)
Pyeongchang Wind Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		25.00%		25.00%
Acquisition cost		₩ 3,875		₩ 3,875
Book value [Abstract]
Beginning balance		3,383		3,402
Share of income (loss)		753		(19)
Ending balance		4,136		3,383
Share in net assets		4,136		3,383
Total assets		77,152		75,440
Total liabilities		60,606		61,909
Net assets		16,546		13,531
Sales of Associates		11,907		3,997
Profit (loss) for the period of Associates		₩ 3,038		₩ (45)
Shareholders’ agreements that may cause future economic resource or cash outflows		In case non-controlling shareholders decide to dispose of their shares in Pyeongchang Wind Power Co., Ltd. after commercial operation of the power plant has started, the Company acquires those shares at fair value. The acquisition is to be made after the conditions of the acquisition are discussed among the parties involved, with the careful consideration of various factors such as financial status and business situation.
Significant restrictions on its abilities		Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained.
Daeryun Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[5],[8]	Power generation		Power generation
Location	[5],[8]	KOREA		KOREA
Percentage of ownership	[5],[8]	13.13%		13.13%
Acquisition cost	[5],[8]	₩ 25,477		₩ 25,477
Book value [Abstract]
Beginning balance		29,873	[5],[8]	36,156
Share of income (loss)		(4,762)		(6,282)
Other comprehensive income (loss)				(1)
Others (book value)		2
Ending balance	[5],[8]	25,113		29,873
Share in net assets		24,095		28,855
Total assets		779,258		793,283
Total liabilities		655,377		644,930
Net assets		123,881		148,353
Investment differential		1,014		1,014
Others (consolidated FS)		4		4
Sales of Associates		156,508		249,558
Profit (loss) for the period of Associates		₩ (23,978)		(32,291)
Significant restrictions on its abilities		Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained.
JinanJangsu Wind Power Co., Ltd. [Member]
Book value [Abstract]
Beginning balance				77
Disposal				64
Share of income (loss)				₩ (13)
Changjuk Wind Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		30.00%		30.00%
Acquisition cost		₩ 3,801		₩ 3,801
Book value [Abstract]
Beginning balance		6,930		6,143
Dividends received		(111)		(190)
Share of income (loss)		696		977
Ending balance		7,515		6,930
Share in net assets		7,515		6,815
Total assets		35,794		37,878
Total liabilities		10,745		15,162
Net assets		25,049		22,716
Others (consolidated FS)				115
Sales of Associates		6,981		5,782
Profit (loss) for the period of Associates		₩ 2,317		₩ 1,739
Significant restrictions on its abilities		Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained.
KNH Solar Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		27.00%		27.00%
Acquisition cost		₩ 1,296		₩ 1,296
Book value [Abstract]
Beginning balance		2,073		1,924
Share of income (loss)		145		144
Other comprehensive income (loss)				5
Ending balance		2,218		2,073
Share in net assets		2,218		2,073
Total assets		24,432		25,878
Total liabilities		16,215		18,199
Net assets		8,217		7,679
Sales of Associates		3,947		4,006
Profit (loss) for the period of Associates		₩ 628		₩ 638
Significant restrictions on its abilities		Principal and interest, dividends to shareholders cannot be paid without written consent of financial institutions.
SPC Power Corporation [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		PHILIPPINES		PHILIPPINES
Percentage of ownership		38.00%		38.00%
Acquisition cost		₩ 20,635		₩ 20,635
Book value [Abstract]
Beginning balance		56,818		58,033
Dividends received		(5,562)		(7,151)
Share of income (loss)		4,310		6,416
Other comprehensive income (loss)		(3,276)		(477)
Others (book value)		(7)		(3)
Ending balance		52,283		56,818
The fair value of associates		72,616		70,253
Share in net assets		52,283		56,818
Total assets		137,586		191,562
Total liabilities				42,042
Net assets		137,586		149,520
Sales of Associates		68,149		73,674
Profit (loss) for the period of Associates		₩ 37,395		₩ 42,617
Gemeng International Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		CHINA		CHINA
Percentage of ownership		34.00%		34.00%
Acquisition cost		₩ 413,153		₩ 413,153
Book value [Abstract]
Beginning balance		680,065		728,396
Dividends received		(13,365)		(16,476)
Share of income (loss)		6,953		26,714
Other comprehensive income (loss)		(23,680)		(58,493)
Others (book value)				(76)
Ending balance		649,973		680,065
Share in net assets		649,973		680,331
Total assets		6,496,294		5,822,879
Total liabilities		4,584,608		3,821,905
Net assets		1,911,686		2,000,974
Others (consolidated FS)				(266)
Sales of Associates		1,334,833		1,233,972
Profit (loss) for the period of Associates		₩ 21,769		₩ 66,370
Shareholders’ agreements that may cause future economic resource or cash outflows		Gemeng International Energy Co., Ltd., issued put options on 8% of its shares to its financial investors, KEPCO Woori Sprott PEF (NPS Co-Pa PEF). If the investment fund is not collected until the maturity date (December 25, 2023, two years extension is possible), PEF can exercise the option at strike price which is the same as a principal investment price (including operating fees ratio of below 1% per annum), and also, the Company provided a performance guarantee on this agreement.
PT. Cirebon Electric Power [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		INDONESIA		INDONESIA
Percentage of ownership		27.50%		27.50%
Acquisition cost		₩ 40,365		₩ 40,365
Book value [Abstract]
Beginning balance		96,658		60,574
Dividends received		(550)		(1,242)
Share of income (loss)		10,685		31,511
Other comprehensive income (loss)		2,232		2,568
Others (book value)		(11,615)		3,247
Ending balance		97,410		96,658
Share in net assets		97,410		96,658
Total assets		903,429		988,975
Total liabilities		549,212		637,491
Net assets		354,217		351,484
Sales of Associates		280,452		265,813
Profit (loss) for the period of Associates		₩ 38,448		₩ 114,653
KNOC Nigerian East Oil [Member]
Disclosure of associates [Line Items]
Key operation activities	[9]	Resources development		Resources development
Location	[9]	NIGERIA		NIGERIA
Percentage of ownership	[9]	14.63%		14.63%
Acquisition cost	[9]	₩ 12		₩ 12
Book value [Abstract]
Share of income (loss)		(1,914)		(1,346)
Other comprehensive income (loss)		1,536		(398)
Others (book value)		378		1,744
Share in net assets		(12,850)		(12,472)
Total assets		241,808		272,964
Total liabilities		329,639		358,211
Net assets		(87,831)		(85,247)
Others (consolidated FS)		12,850		12,472
Profit (loss) for the period of Associates		₩ (10,754)		₩ (7,051)
KNOC Nigerian West Oil [Member]
Disclosure of associates [Line Items]
Key operation activities	[9]	Resources development		Resources development
Location	[9]	NIGERIA		NIGERIA
Percentage of ownership	[9]	14.63%		14.63%
Acquisition cost	[9]	₩ 12		₩ 12
Book value [Abstract]
Share of income (loss)		(1,712)		(973)
Other comprehensive income (loss)		1,407		(356)
Others (book value)		305		1,329
Share in net assets		(11,763)		(11,458)
Total assets		147,185		165,396
Total liabilities		227,588		243,713
Net assets		(80,403)		(78,317)
Others (consolidated FS)		11,763		11,458
Profit (loss) for the period of Associates		₩ (9,768)		(6,562)
Dolphin Property Limited [Member]
Book value [Abstract]
Beginning balance				61
Dividends received				(35)
Other comprehensive income (loss)				(69)
Others (book value)				₩ 43
PT Wampu Electric Power [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		INDONESIA		INDONESIA
Percentage of ownership		46.00%		46.00%
Acquisition cost		₩ 21,292		₩ 21,292
Book value [Abstract]
Beginning balance		23,188		18,963
Share of income (loss)		9,336		3,493
Other comprehensive income (loss)				(3)
Others (book value)		(3,121)		735
Ending balance		29,403		23,188
Share in net assets		29,403		23,188
Total assets		212,095		222,004
Total liabilities		148,177		171,595
Net assets		63,918		50,409
Sales of Associates		779		19,260
Profit (loss) for the period of Associates		₩ 8,114		₩ 7,550
PT. Bayan Resources TBK [Member]
Disclosure of associates [Line Items]
Key operation activities		Resources development		Resources development
Location		INDONESIA		INDONESIA
Percentage of ownership		20.00%		20.00%
Acquisition cost		₩ 615,860		₩ 615,860
Book value [Abstract]
Beginning balance		402,667		525,066
Share of income (loss)		34,122		(23,257)
Other comprehensive income (loss)		14,982		208
Others (book value)		60		(99,350)
Ending balance		451,831		402,667
The fair value of associates		558,267		359,200
Share in net assets		70,245		19,895
Total assets		908,106		945,436
Total liabilities		556,881		845,963
Net assets		351,225		99,473
Investment differential		482,109		482,109
Others (consolidated FS)		(100,523)		(99,337)
Sales of Associates		811,515		593,441
Profit (loss) for the period of Associates		₩ 243,621		₩ 402
S-Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		49.00%		49.00%
Acquisition cost		₩ 132,300		₩ 132,300
Book value [Abstract]
Beginning balance		123,912		130,908
Share of income (loss)		(6,982)		(7,006)
Others (book value)		15		10
Ending balance		116,945		123,912
Share in net assets		118,780		125,856
Total assets		859,633		886,841
Total liabilities		617,224		629,992
Net assets		242,409		256,849
Intercompany transaction		(1,835)		(1,944)
Sales of Associates		489,042		453,606
Profit (loss) for the period of Associates		₩ (14,470)		₩ (14,885)
Pioneer Gas Power Limited [Member]
Disclosure of associates [Line Items]
Key operation activities	[10]	Power generation		Power generation
Location	[10]	INDIA		INDIA
Percentage of ownership	[10]	38.50%		40.00%
Acquisition cost	[10]	₩ 49,831		₩ 49,831
Book value [Abstract]
Beginning balance		50,740	[10]	51,187
Share of income (loss)		(11,119)		(698)
Other comprehensive income (loss)		(1,238)		251
Others (book value)		276
Ending balance	[10]	38,659		50,740
Share in net assets		16,314		27,525
Total assets		339,271		345,791
Total liabilities		296,898		276,978
Net assets		42,373		68,813
Investment differential		22,278		23,147
Others (consolidated FS)		67		68
Sales of Associates		8,215		14,353
Profit (loss) for the period of Associates		₩ (27,796)		₩ 396
Eurasia Energy Holdings [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation and resources development		Power generation and resources development
Location		RUSSIA		RUSSIA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 461		₩ 461
Book value [Abstract]
Share in net assets		(172)		(194)
Total assets		548		618
Total liabilities		978		1,103
Net assets		(430)		(485)
Others (consolidated FS)		172		194
Unrecognized equity interest		(22)		6
Accumulated unrecognized equity interest		₩ 172		₩ 194
Xe-Pian Xe-Namnoy Power [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		LAOS		LAOS
Percentage of ownership		25.00%		25.00%
Acquisition cost		₩ 71,481		₩ 49,119
Book value [Abstract]
Beginning balance		51,544		31,863
Acquisition		22,362		16,402
Share of income (loss)		(4,264)		1,576
Other comprehensive income (loss)		(7,863)		1,703
Ending balance		61,779		51,544
Share in net assets		62,832		57,307
Total assets		858,789		772,699
Total liabilities		607,462		543,472
Net assets		251,327		229,227
Investment differential		74		(4,802)
Intercompany transaction		(838)		(672)
Others (consolidated FS)		(289)		(289)
Profit (loss) for the period of Associates		₩ (16,677)		6,458
Busan Solar [Member]
Book value [Abstract]
Beginning balance				925
Disposal				887
Share of income (loss)				₩ (38)
Hadong Mineral Fiber Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Recycling fly ashes	[5]	Recycling fly ashes	[11]
Location		KOREA	[5]	KOREA	[11]
Percentage of ownership		8.33%	[5]	8.33%	[11]
Acquisition cost		₩ 50	[5]	₩ 50	[11]
Book value [Abstract]
Share of income (loss)		(31)
Others (book value)		31
Share in net assets		(2)		(5)
Total assets		203
Total liabilities		231		20
Net assets		(28)		(20)
Others (consolidated FS)		2		5
Profit (loss) for the period of Associates		(260)
Unrecognized equity interest		(3)
Accumulated unrecognized equity interest		₩ 2		₩ 5
Green Biomass Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[12]	Power generation	[13]	Power generation
Location	[12]	KOREA	[13]	KOREA
Percentage of ownership	[12]	8.80%	[13]	14.00%
Acquisition cost	[12]	₩ 714	[13]	₩ 714
Book value [Abstract]
Beginning balance	[12]	47
Share of income (loss)		(112)		(138)
Others (book value)		273		185
Ending balance	[12]	208	[13]	47
Share in net assets		208		47
Total assets		6,379		9,336
Total liabilities		4,018		9,001
Net assets		2,361		335
Sales of Associates		2,337		2,892
Profit (loss) for the period of Associates		₩ (956)		₩ (972)
PT. Mutiara Jawa [Member]
Disclosure of associates [Line Items]
Key operation activities		Manufacturing and operating floating coal terminal		Manufacturing and operating floating coal terminal
Location		INDONESIA		INDONESIA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 2,978		₩ 2,978
Book value [Abstract]
Share in net assets		(746)		(1,904)
Total assets		27,098		28,104
Total liabilities		29,670		34,671
Net assets		(2,572)		(6,567)
Investment differential				70
Others (consolidated FS)		746		1,834
Sales of Associates		13,574		7,175
Profit (loss) for the period of Associates		3,455		(1,361)
Unrecognized equity interest		(1,159)		554
Accumulated unrecognized equity interest		₩ 746		₩ 1,905
Samcheok Eco Materials Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[14]	Recycling fly ashes		Recycling fly ashes	[5]
Location	[14]	KOREA		KOREA	[5]
Percentage of ownership	[14]	2.35%		2.35%	[5]
Acquisition cost	[14]	₩ 686		₩ 686	[5]
Book value [Abstract]
Share in net assets		551		561
Total assets		23,729		24,143
Total liabilities		270		254
Net assets		23,459		23,889
Others (consolidated FS)		(551)		(561)
Sales of Associates		15
Profit (loss) for the period of Associates		₩ (541)		₩ (1,945)
Shareholders’ agreements that may cause future economic resource or cash outflows		The Company has the rights to purchase the stocks should preferred stockholders elect to sell their stocks on the expected sell date (3 years from preferred stock payment date) and is required to guarantee the promised yield when preferred stockholders sell their stocks.
Noeul Green Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 1,740		₩ 1,740
Book value [Abstract]
Beginning balance		1,217		295
Acquisition				1,340
Share of income (loss)		850		(418)
Ending balance		2,067		1,217
Share in net assets		2,067		1,217
Total assets		127,980		115,062
Total liabilities		120,852		110,866
Net assets		7,128		4,196
Sales of Associates		43,099		203
Profit (loss) for the period of Associates		₩ 2,932		₩ (1,155)
Naepo Green Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		41.67%		25.00%
Acquisition cost		₩ 29,200		₩ 29,200
Book value [Abstract]
Beginning balance		25,438		26,746
Share of income (loss)		(1,400)		(1,308)
Others (book value)		(3,440)
Ending balance		20,598		25,438
Share in net assets		20,598		25,438
Total assets		121,375		104,029
Total liabilities		71,945		2,276
Net assets		49,430		101,753
Sales of Associates		5,696		4,912
Profit (loss) for the period of Associates		₩ (5,603)		₩ (5,230)
Goseong Green Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[2]	Power generation		Power generation
Location	[2]	KOREA		KOREA
Percentage of ownership	[2]	1.12%		1.12%
Acquisition cost	[2]	₩ 2,900		₩ 2,900
Book value [Abstract]
Beginning balance		2,663	[2]	2,670
Share of income (loss)		(66)		71
Others (book value)				(78)
Ending balance	[2]	2,597		2,663
Share in net assets		2,676		2,742
Total assets		1,081,238		356,546
Total liabilities		841,330		110,753
Net assets		239,908		245,793
Intercompany transaction		(79)		(79)
Profit (loss) for the period of Associates		₩ (5,811)		₩ (5,489)
Gangneung Eco Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[2]	Power generation		Power generation
Location	[2]	KOREA		KOREA
Percentage of ownership	[2]	1.61%		1.61%
Acquisition cost	[2]	₩ 2,900		₩ 2,900
Book value [Abstract]
Beginning balance		2,646	[2]	2,688
Share of income (loss)		(63)		56
Others (book value)				(98)
Ending balance	[2]	2,583		2,646
Share in net assets		2,681		2,744
Total assets		186,765		176,805
Total liabilities		20,344		6,503
Net assets		166,421		170,302
Intercompany transaction		(98)		(98)
Profit (loss) for the period of Associates		₩ (3,407)		₩ (3,494)
Shin Pyeongtaek Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 43,920		₩ 40
Book value [Abstract]
Acquisition		43,880
Share of income (loss)		(10,998)
Other comprehensive income (loss)		(3,617)
Others (book value)		5,638
Ending balance		34,903
Share in net assets		34,083		(2,538)
Total assets		175,870		54,174
Total liabilities		90,662		60,518
Net assets		85,208		(6,344)
Investment differential		7,808
Intercompany transaction		(6,988)		(3,380)
Others (consolidated FS)				5,918
Profit (loss) for the period of Associates		(4,585)		(3,291)
Unrecognized equity interest		₩ (2,537)		1,211
Accumulated unrecognized equity interest				₩ 2,537
Heang Bok Do Si Photovoltaic Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		28.00%		28.00%
Acquisition cost		₩ 194		₩ 194
Book value [Abstract]
Beginning balance		181		189
Share of income (loss)		6		(10)
Others (book value)				2
Ending balance		187		181
Share in net assets		185		179
Total assets		2,782		2,937
Total liabilities		2,120		2,297
Net assets		662		640
Others (consolidated FS)		2		2
Sales of Associates		451		427
Profit (loss) for the period of Associates		₩ 22		₩ (47)
DS POWER Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation	[2]
Location		KOREA		KOREA	[2]
Percentage of ownership	[2]			14.44%
Acquisition cost	[2]			₩ 17,900
Book value [Abstract]
Beginning balance		₩ 7,190	[2]	10,960
Share of income (loss)		(1,321)		(3,738)
Others (book value)		₩ (5,869)		(32)
Ending balance	[2]			7,190
Share in net assets				15,582
Total assets				726,699
Total liabilities				618,793
Net assets				107,906
Intercompany transaction				(7,302)
Others (consolidated FS)				(1,090)
Sales of Associates				276,324
Profit (loss) for the period of Associates				₩ (10,031)
Dongducheon Dream Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		33.61%		33.61%
Acquisition cost		₩ 111,134		₩ 61,535
Book value [Abstract]
Beginning balance		46,876		55,667
Share of income (loss)		(10,980)		(8,757)
Others (book value)		17,337		(34)
Ending balance		53,233		46,876
Share in net assets		70,356		81,730
Total assets		1,575,175		1,670,945
Total liabilities		1,365,845		1,427,773
Net assets		209,330		243,172
Intercompany transaction		(4,409)		(4,768)
Others (consolidated FS)		(12,714)		(30,086)
Sales of Associates		813,440		946,379
Profit (loss) for the period of Associates		₩ (33,740)		₩ (27,936)
KS Solar Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation	[5]
Location		KOREA		KOREA	[5]
Percentage of ownership	[5]			19.00%
Acquisition cost	[5]			₩ 637
Book value [Abstract]
Beginning balance		₩ 604	[5]	618
Disposal		(613)
Share of income (loss)				(14)
Other comprehensive income (loss)		₩ 9
Ending balance	[5]			604
Share in net assets				604
Total assets				27,213
Total liabilities				24,035
Net assets				3,178
Sales of Associates				4,152
Profit (loss) for the period of Associates				₩ (79)
Yeongwol Energy Station Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[2]			Power generation
Location	[2]			KOREA
Percentage of ownership	[2]			10.00%
Acquisition cost	[2]			₩ 1,400
Book value [Abstract]
Beginning balance				1,290
Share of income (loss)				85
Other comprehensive income (loss)				25
Others (book value)				₩ (1,400)
Jinbhuvish Power Generation Pvt. Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[2]	Power generation		Power generation
Location	[2]	INDIA		INDIA
Percentage of ownership	[2]	5.16%		5.16%
Acquisition cost	[2]	₩ 9,000		₩ 9,000
Book value [Abstract]
Beginning balance				8,350
Share of income (loss)				(49)
Other comprehensive income (loss)				(198)
Others (book value)				(8,103)
Share in net assets		2,704		2,877
Total assets		66,047		70,273
Total liabilities		13,640		14,513
Net assets		52,407		55,760
Others (consolidated FS)		₩ (2,704)		(2,877)
Profit (loss) for the period of Associates				₩ (950)
SE Green Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation support		Power generation support
Location		KOREA		KOREA
Percentage of ownership		47.76%		47.76%
Acquisition cost		₩ 3,821		₩ 3,821
Book value [Abstract]
Beginning balance		3,525		3,575
Share of income (loss)		(49)		(50)
Ending balance		3,476		3,525
Share in net assets		3,476		3,525
Total assets		7,278		7,381
Net assets		7,278		7,381
Profit (loss) for the period of Associates		₩ (103)		₩ (103)
Daegu Photovoltaic Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 1,230		₩ 1,230
Book value [Abstract]
Beginning balance		1,700		1,886
Dividends received		(349)		(411)
Share of income (loss)		367		225
Ending balance		1,718		1,700
Share in net assets		1,718		1,700
Total assets		17,262		18,909
Total liabilities		11,339		13,047
Net assets		5,923		5,862
Sales of Associates		3,714		3,317
Profit (loss) for the period of Associates		₩ 1,263		₩ 739
Jeongam Wind Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 5,580		₩ 5,580
Book value [Abstract]
Beginning balance		4,000		702
Acquisition				3,900
Share of income (loss)		(237)		(602)
Ending balance		3,763		4,000
Share in net assets		3,763		4,000
Total assets		67,427		13,199
Total liabilities		58,019		3,199
Net assets		9,408		10,000
Profit (loss) for the period of Associates		₩ (580)		₩ (1,496)
Shareholders’ agreements that may cause future economic resource or cash outflows		In case non-controlling shareholders decide to dispose of their shares in Jeongam Wind Power Co., Ltd. after the construction of the power plant has been completed, the Company is obligated to acquire those shares at fair value.
Korea Power Engineering Service Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Construction and service		Construction and service
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 290		₩ 290
Book value [Abstract]
Beginning balance		2,810		1,805
Dividends received		(191)
Share of income (loss)		1,030		1,005
Others (book value)		10
Ending balance		3,659		2,810
Share in net assets		3,659		2,810
Total assets		15,738		13,401
Total liabilities		3,121		3,713
Net assets		12,617		9,688
Sales of Associates		22,283		27,394
Profit (loss) for the period of Associates		₩ 3,783		₩ 3,463
Busan Green Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 5,243		₩ 14,564
Book value [Abstract]
Beginning balance		13,803		14,512
Disposal		(9,320)
Share of income (loss)		2,884		(709)
Others (book value)		(4)
Ending balance		7,363		13,803
Share in net assets		7,363		13,803
Total assets		193,253		147,843
Total liabilities		167,864		100,247
Net assets		25,389		47,596
Sales of Associates		34,280
Profit (loss) for the period of Associates		₩ 9,946		₩ (2,444)
Gunsan Bio Energy Co., Ltd. (formerly, Jungbu Bio Energy Co., Ltd.) [Member]
Disclosure of associates [Line Items]
Key operation activities	[2]	Power generation		Power generation
Location	[2]	KOREA		KOREA
Percentage of ownership	[2]	18.87%		18.87%
Acquisition cost	[2]	₩ 1,000		₩ 1,000
Book value [Abstract]
Beginning balance				904
Share of income (loss)				(904)
Share in net assets		(1,286)		(132)
Total assets		9,648		11,340
Total liabilities		16,462		12,037
Net assets		(6,814)		(697)
Others (consolidated FS)		1,286		132
Profit (loss) for the period of Associates		(6,109)		(5,489)
Unrecognized equity interest		1,154		132
Accumulated unrecognized equity interest		₩ 1,286		₩ 132
Korea Electric Vehicle Charging Service [Member]
Disclosure of associates [Line Items]
Key operation activities		Electric vehicle charge service		Electric vehicle charge service
Location		KOREA		KOREA
Percentage of ownership		28.00%		28.00%
Acquisition cost		₩ 2,604		₩ 1,596
Book value [Abstract]
Beginning balance		1,103		1,446
Acquisition		1,008
Share of income (loss)		(362)		(343)
Ending balance		1,749		1,103
Share in net assets		1,749		1,103
Total assets		14,650		10,545
Total liabilities		8,404		6,604
Net assets		6,246		3,941
Sales of Associates		8,399		5,177
Profit (loss) for the period of Associates		₩ (1,295)		₩ (1,225)
Ulleungdo Natural Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Renewable power generation		Renewable power generation
Location		KOREA		KOREA
Percentage of ownership		29.85%		29.85%
Acquisition cost		₩ 8,000		₩ 8,000
Book value [Abstract]
Beginning balance		6,894		7,417
Share of income (loss)		(524)		(516)
Others (book value)				(7)
Ending balance		6,370		6,894
Share in net assets		6,370		6,895
Total assets		25,842		24,836
Total liabilities		4,501		1,738
Net assets		21,341		23,098
Others (consolidated FS)				(1)
Profit (loss) for the period of Associates		₩ (1,758)		₩ (1,730)
Korea Nuclear Partners Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Electric material agency		Electric material agency
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 290		₩ 290
Book value [Abstract]
Beginning balance		248		289
Share of income (loss)		135		(41)
Ending balance		383		248
Share in net assets		383		248
Total assets		2,033		1,363
Total liabilities		711		507
Net assets		1,322		856
Sales of Associates		1,345		372
Profit (loss) for the period of Associates		₩ 465		₩ (140)
Tamra Offshore Wind Power Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		27.00%		27.00%
Acquisition cost		₩ 8,910		₩ 8,910
Book value [Abstract]
Beginning balance		7,015
Acquisition				8,910
Share of income (loss)		1,545		(1,895)
Ending balance		8,560		7,015
Share in net assets		8,560		7,015
Total assets		163,740		127,880
Total liabilities		132,036		101,900
Net assets		31,704		25,980
Sales of Associates		4,392		983
Profit (loss) for the period of Associates		₩ (191)		₩ (6,307)
Korea Electric Power Corporation Fund [Member]
Disclosure of associates [Line Items]
Key operation activities	[15]	Developing electric enterprises		Developing electric enterprises
Location	[15]	KOREA		KOREA
Percentage of ownership	[15]	98.09%		98.09%
Acquisition cost	[15]	₩ 51,500		₩ 51,500
Book value [Abstract]
Beginning balance	[15]	50,856
Acquisition				51,500
Share of income (loss)		(2,171)		(644)
Other comprehensive income (loss)		(711)
Ending balance	[15]	47,974		50,856
Share in net assets		47,971		50,852
Total assets		49,170		51,970
Total liabilities		265		128
Net assets		48,905		51,842
Others (consolidated FS)		3		4
Sales of Associates		666		3
Profit (loss) for the period of Associates		₩ (2,213)		₩ (647)
Energy Infra Asset Management Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities	[5]	Asset management		Asset management
Location	[5]	KOREA		KOREA
Percentage of ownership	[5]	9.90%		9.90%
Acquisition cost	[5]	₩ 297		₩ 297
Book value [Abstract]
Beginning balance	[5]	259
Acquisition				297
Share of income (loss)		217		(38)
Ending balance	[5]	476		259
Share in net assets		476		259
Total assets		5,240		2,779
Total liabilities		431		160
Net assets		4,809		2,619
Sales of Associates		5,807		32
Profit (loss) for the period of Associates		₩ 2,203		₩ (381)
Daegu clean Energy Co., Ltd. [Member]
Disclosure of associates [Line Items]
Key operation activities		Renewable power generation		Renewable power generation
Location		KOREA		KOREA
Percentage of ownership		28.00%		28.00%
Acquisition cost		₩ 140		₩ 140
Book value [Abstract]
Beginning balance		140
Acquisition				140
Share of income (loss)		(129)
Ending balance		11		140
Share in net assets		11		140
Total assets		252		500
Total liabilities		212
Net assets		40		₩ 500
Profit (loss) for the period of Associates		₩ (460)
YaksuESS Co., Ltd [Member]
Disclosure of associates [Line Items]
Key operation activities		Installing ESS related equipment		Installing ESS related equipment
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 210		₩ 210
Book value [Abstract]
Beginning balance		196
Acquisition				210
Share of income (loss)		(2)		(14)
Ending balance		194		196
Share in net assets		193		195
Total assets		7,105		6,474
Total liabilities		6,437		5,801
Net assets		668		673
Others (consolidated FS)		1		1
Sales of Associates		381
Profit (loss) for the period of Associates		₩ (6)		₩ (48)
Nepal Water & Energy Development Company Private Limited [Member]
Disclosure of associates [Line Items]
Key operation activities	[16]	Construction and operation of utility plant		Construction and operation of utility plant
Location	[16]	NEPAL		NEPAL
Percentage of ownership	[16]	62.13%		52.77%
Acquisition cost	[16]	₩ 33,577		₩ 18,568
Book value [Abstract]
Beginning balance	[16]	18,667
Acquisition		15,009
Share of income (loss)		(677)
Other comprehensive income (loss)		(2,501)
Others (book value)				18,667
Ending balance	[16]	30,498		18,667
Share in net assets		28,860		17,578
Total assets		58,121		43,788
Total liabilities		11,670		10,477
Net assets		46,451		33,311
Investment differential		972		972
Others (consolidated FS)		666		117
Profit (loss) for the period of Associates		₩ (968)		₩ (703)
Gwangyang Green Energy Co., Ltd [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation
Location		KOREA
Percentage of ownership		20.00%
Acquisition cost		₩ 2,000
Book value [Abstract]
Acquisition		2,000
Share of income (loss)		(228)
Ending balance		1,772
Share in net assets		1,754
Total assets		20,165
Total liabilities		11,393
Net assets		8,772
Investment differential		18
Profit (loss) for the period of Associates		₩ (1,139)
PND solar., Ltd [Member]
Disclosure of associates [Line Items]
Key operation activities		Power generation
Location		KOREA
Percentage of ownership		29.00%
Acquisition cost		₩ 1,250
Book value [Abstract]
Acquisition		1,250
Ending balance		1,250
Share in net assets		1,096
Total assets		10,508
Total liabilities		6,729
Net assets		3,779
Investment differential		154
Profit (loss) for the period of Associates		₩ (406)
[1]	The effective percentage of ownership is 21.57% considering treasury stocks.
[2]	The Company can exercise significant influence by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors.
[3]	The Government regulates the Company’s ability to make operating and financial decisions over the entity, as the Government requires maintaining arms-length transactions between KPX and the Company’s other subsidiaries. The Company can exercise significant influence by its right to nominate directors to the board of directors of the entity.
[4]	The Government regulates the Company’s ability to make operating and financial decisions over the entity, as the Government requires maintaining arms-length transactions between KPX and the Company’s other subsidiaries. The Company can exercise significant influence by its right to nominate directors to the board of directors of the entity.
[5]	The Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity.
[6]	As of December 31, 2017, 15.64% of ownership of Hyundai Energy Co., Ltd. is held by NH Power II Co., Ltd. and NH Bank. According to the shareholders’ agreement reached on March 2011, not only does the Company have a call option to acquire the investment in Hyundai Energy Co., Ltd. from NH Power II Co., Ltd. and NH Bank with a certain rate of return, NH Power II Co., Ltd. and NH Bank also have put options to dispose of their investment to the Company. In connection with this agreement, the Company applied the equity method on the investment in Hyundai Energy Co., Ltd. with 46.30% of ownership.
[7]	As of December 31, 2016, 15.64% of ownership of Hyundai Energy Co., Ltd. is held by NH Power II Co., Ltd. and NH Bank. According to the shareholders’ agreement reached on March 2011, not only does the Company have a call option to acquire the investment in Hyundai Energy Co., Ltd. from NH Power II Co., Ltd. and NH Bank with a certain rate of return, NH Power II Co., Ltd. and NH Bank also have put options to dispose of their investment to the Company. In connection with this agreement, the Company applied the equity method on the investment in Hyundai Energy Co., Ltd. with 46.30% of ownership.
[8]	The Company’s percentage of ownership has decreased due to the acquisition of Daeryun Power Co., Ltd. and the effective percentage of ownership is 19.45% considering stock purchase options.
[9]	The Company can exercise significant influence by virtue of its contractual right to appoint one out of four members of the steering committee of the entity. Moreover, the Company has significant financial transactions, which can affect its influence on the entity.
[10]	As of reporting date, the annual reporting period of all associates and joint ventures ends on December 31, except for Pioneer Gas Power Limited whose reporting period ends on March 31.
[11]	Although the percentage of ownership temporarily decreased to 8.33% from the difference in timing of capital payment by shareholders, the Company can exercise significant influence by virtue of its right to appoint a director to the board of directors of the entity based on the shareholders’ agreement. The percentage of ownership is 25.00% at the time of completion of capital payment.
[12]	The effective percentage of ownership is less than 20% but the Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity and the fact that the dominant portion of the investee’s sales transactions is generated from the Company.
[13]	The percentage of ownership decreased since the Company did not participate in the capital increase of Green Biomass Co., Ltd. during the period.
[14]	The Company’s effective percentage of ownership excluding the redeemable convertible preferred stock is 25.54%.
[15]	The effective percentage of ownership is more than 50% but the Company does not hold control over relevant business while it exercises significant influence by participating in the Investment Decision Committee. For this reason, the entity is classified as an associate.
[16]	The effective percentage of ownership is more than 50% but the Company does not hold control over the entity according to the shareholders’ agreement. For this reason, the entity is classified as an associate.

Investments in Joint Ventures (

Investments in Joint Ventures (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
KEPCO-Uhde Inc. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation		Power generation
Location	[1]	KOREA		KOREA
Percentage of ownership	[1]	52.80%		52.80%
Acquisition cost	[1]	₩ 11,355		₩ 11,355
Book value [Abstract]
Beginning balance		301	[1]	8,549
Share of income (loss)		(43)		(159)
Others (book value)				(8,089)
Ending balance	[1]	258		301
Share in net assets		258		301
Total assets		515		624
Total liabilities		7		33
Net assets		508		591
Profit (loss) for the period of JointVentures		₩ (86)		₩ (16,855)
Eco Biomass Energy Sdn. Bhd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation		Power generation
Location	[1]	MALAYSIA		MALAYSIA
Percentage of ownership	[1]	61.53%		61.53%
Acquisition cost	[1]	₩ 14,439		₩ 9,661
Datang Chaoyang Renewable Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		CHINA		CHINA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 27,660		₩ 27,660
Book value [Abstract]
Beginning balance		28,239		27,640
Dividends received		(839)
Share of income (loss)		840		1,417
Other comprehensive income (loss)		(978)		(818)
Ending balance		27,262		28,239
Share in net assets		27,262		28,239
Total assets		138,463		142,684
Total liabilities		70,309		72,086
Net assets		68,154		70,598
Sales of JointVentures		17,776		18,628
Profit (loss) for the period of JointVentures		₩ 2,149		₩ 3,462
Shuweihat Asia Power Investment B.V. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Holding company		Holding company	[1]
Location		NETHERLANDS		NETHERLANDS	[1]
Percentage of ownership		49.00%		49.00%	[1]
Acquisition cost		₩ 46,037		₩ 46,037	[1]
Book value [Abstract]
Beginning balance				20,474
Disposal				(14,154)
Dividends received		(1,707)		(2,957)
Share of income (loss)		4,275		6,131
Other comprehensive income (loss)		12,457		(9,494)
Others (book value)		650
Ending balance		15,675
Share in net assets		15,675		136
Total assets		32,001		282
Total liabilities		10		4
Net assets		31,991		278
Others (consolidated FS)				(136)
Profit (loss) for the period of JointVentures		₩ (170)		₩ 12,380
Shuweihat Asia Operation & Maintenance Company [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Maintenance of utility plant	[1]	Maintenance of utility plant
Location		CAYMAN	[1]	CAYMAN
Percentage of ownership		55.00%	[1]	55.00%
Acquisition cost		₩ 30	[1]	₩ 30
Book value [Abstract]
Beginning balance		450		486
Dividends received		(770)		(931)
Share of income (loss)		1,055		941
Other comprehensive income (loss)		(172)		(46)
Others (book value)		100
Ending balance		663	[1]	450
Share in net assets		663		552
Total assets		1,220		1,016
Total liabilities		14		13
Net assets		1,206		1,003
Others (consolidated FS)				(102)
Sales of JointVentures		2,580		2,388
Profit (loss) for the period of JointVentures		₩ 1,918		₩ 1,723
Waterbury Lake Uranium L.P. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Resources development		Resources development
Location		CANADA		CANADA
Percentage of ownership		35.76%		36.97%
Acquisition cost		₩ 26,602		₩ 26,602
Book value [Abstract]
Beginning balance		21,314		20,299
Share of income (loss)		(23)
Other comprehensive income (loss)		(949)		1,138
Others (book value)		(561)		(123)
Ending balance		19,781		21,314
Share in net assets		19,780		20,753
Total assets		55,563		56,181
Total liabilities		250		47
Net assets		55,313		56,134
Others (consolidated FS)		₩ 1		₩ 561
ASM-BG Investicii AD [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		BULGARIA		BULGARIA
Percentage of ownership		50.00%		50.00%
Acquisition cost		₩ 16,101		₩ 16,101
Book value [Abstract]
Beginning balance		21,488		20,203
Dividends received		(946)
Share of income (loss)		(150)		1,508
Other comprehensive income (loss)		810		(223)
Ending balance		21,202		21,488
Share in net assets		21,202		21,489
Total assets		87,110		79,898
Total liabilities		44,706		36,921
Net assets		42,404		42,977
Others (consolidated FS)				(1)
Sales of JointVentures		12,611		12,604
Profit (loss) for the period of JointVentures		₩ (262)		₩ 3,105
RES Technology AD [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		BULGARIA		BULGARIA
Percentage of ownership		50.00%		50.00%
Acquisition cost		₩ 15,595		₩ 15,595
Book value [Abstract]
Beginning balance		13,582		13,789
Share of income (loss)		1,053		(68)
Other comprehensive income (loss)		(260)		(139)
Ending balance		14,375		13,582
Share in net assets		14,375		13,582
Total assets		71,595		68,553
Total liabilities		42,845		41,389
Net assets		28,750		27,164
Sales of JointVentures		7,793		7,798
Profit (loss) for the period of JointVentures		₩ 2,164		₩ (139)
KV Holdings, Inc. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		PHILIPPINES		PHILIPPINES
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 2,103		₩ 2,103
Book value [Abstract]
Beginning balance		2,098		2,010
Dividends received				(302)
Share of income (loss)		61		429
Other comprehensive income (loss)		(241)		(39)
Ending balance		1,918		2,098
Share in net assets		1,918		2,098
Total assets		4,795		5,245
Total liabilities				1
Net assets		4,795		5,244
Sales of JointVentures		671
Profit (loss) for the period of JointVentures		₩ 677		₩ 1,072
KEPCO SPC Power Corporation [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Construction and operation of utility plant		Construction and operation of utility plant
Location	[1]	PHILIPPINES		PHILIPPINES
Percentage of ownership	[1]	75.20%		75.20%
Acquisition cost	[1]	₩ 94,579		₩ 94,579
Book value [Abstract]
Beginning balance		245,367	[1]	208,524
Dividends received		(37,443)		(5,955)
Share of income (loss)		42,359		48,132
Other comprehensive income (loss)		(33,230)		(5,308)
Others (book value)		41		(26)
Ending balance	[1]	217,094		245,367
Share in net assets		217,094		245,367
Total assets		318,911		448,069
Total liabilities		30,222		121,783
Net assets		288,689		326,286
Sales of JointVentures		186,725		165,046
Profit (loss) for the period of JointVentures		₩ 57,364		₩ 63,689
Canada Korea Uranium Limited Partnership [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[2]			Resources development
Location	[2]			CANADA
Percentage of ownership	[2]			12.50%
Acquisition cost	[2]			₩ 5,404
Book value [Abstract]
Share in net assets				18
Total assets				285
Total liabilities				144
Net assets				141
Others (consolidated FS)				(18)
Profit (loss) for the period of JointVentures				₩ (59)
Gansu Datang Yumen Wind Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		CHINA		CHINA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 16,621		₩ 16,621
Book value [Abstract]
Beginning balance		12,821		16,107
Share of income (loss)		(1,299)		(2,836)
Other comprehensive income (loss)		(682)		(450)
Ending balance		10,840		12,821
Share in net assets		10,840		12,821
Total assets		81,960		89,517
Total liabilities		54,859		57,464
Net assets		27,101		32,053
Sales of JointVentures		6,938		4,263
Profit (loss) for the period of JointVentures		₩ (3,253)		₩ (6,815)
Datang Chifeng Renewable Power [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		CHINA		CHINA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 121,928		₩ 121,928
Book value [Abstract]
Beginning balance		166,535		171,224
Dividends received				(7,384)
Share of income (loss)		14,079		7,455
Other comprehensive income (loss)		(9,559)		(4,760)
Ending balance		171,055		166,535
Share in net assets		171,105		166,584
Total assets		762,605		813,804
Total liabilities		334,843		397,344
Net assets		427,762		416,460
Others (consolidated FS)		(50)		(49)
Sales of JointVentures		113,329		99,795
Profit (loss) for the period of JointVentures		₩ 35,294		₩ 19,042
Datang KEPCO Chaoyang Renewable Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		CHINA		CHINA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 10,858		₩ 10,858
Book value [Abstract]
Beginning balance		10,843		10,580
Dividends received				(440)
Share of income (loss)		837		1,002
Other comprehensive income (loss)		(620)		(299)
Ending balance		11,060		10,843
Share in net assets		11,060		10,843
Total assets		60,913		62,600
Total liabilities		33,264		35,493
Net assets		27,649		27,107
Sales of JointVentures		8,442		8,742
Profit (loss) for the period of JointVentures		₩ 2,094		₩ 2,505
Rabigh Electricity Company [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		SAUDI ARABIA		SAUDI ARABIA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 109,743		₩ 109,743
Book value [Abstract]
Beginning balance		97,802		59,368
Dividends received		(18,112)
Share of income (loss)		35,769		18,961
Other comprehensive income (loss)		(15,227)		19,473
Others (book value)		(876)
Ending balance		99,356		97,802
Share in net assets		171,248		173,153
Total assets		2,364,522		2,691,654
Total liabilities		1,936,403		2,258,772
Net assets		428,119		432,882
Intercompany transaction		(70,978)		(75,311)
Others (consolidated FS)		(914)		(40)
Sales of JointVentures		287,105		278,431
Profit (loss) for the period of JointVentures		₩ 78,948		₩ 37,791
Rabigh Operation & Maintenance Company [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Maintenance of utility plant		Maintenance of utility plant
Location		SAUDI ARABIA		SAUDI ARABIA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 70		₩ 70
Book value [Abstract]
Beginning balance		4,427		3,586
Dividends received		(2,130)		(1,934)
Share of income (loss)		2,236		2,253
Other comprehensive income (loss)		(546)		229
Others (book value)				293
Ending balance		3,987		4,427
Share in net assets		3,987		4,427
Total assets		19,992		25,032
Total liabilities		10,025		13,965
Net assets		9,967		11,067
Sales of JointVentures		22,668		25,607
Profit (loss) for the period of JointVentures		₩ 5,668		₩ 4,870
Jamaica Public Service Company Limited [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		JAMAICA		JAMAICA
Percentage of ownership		40.00%		40.00%
Acquisition cost		₩ 301,910		₩ 301,910
Book value [Abstract]
Beginning balance		249,453		241,918
Other comprehensive income (loss)		(28,300)		7,535
Ending balance		221,153		249,453
Share in net assets		209,464		252,685
Total assets		1,276,279		1,291,008
Total liabilities		752,617		659,296
Net assets		523,662		631,712
Investment differential		(80,161)		(80,161)
Others (consolidated FS)		91,850		76,929
Sales of JointVentures		946,365		827,298
Profit (loss) for the period of JointVentures		₩ 24,601		₩ 25,324
KW Nuclear Components Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Manufacturing		Manufacturing
Location		KOREA		KOREA
Percentage of ownership		45.00%		45.00%
Acquisition cost		₩ 833		₩ 833
Book value [Abstract]
Beginning balance		7,133		4,985
Dividends received		(208)		(2,191)
Share of income (loss)		(222)		4,344
Others (book value)				(5)
Ending balance		6,703		7,133
Share in net assets		6,962		6,492
Total assets		25,693		26,417
Total liabilities		10,221		11,990
Net assets		15,472		14,427
Investment differential				90
Others (consolidated FS)		(259)		551
Sales of JointVentures		6,486		26,481
Profit (loss) for the period of JointVentures		₩ 1,493		₩ 9,452
Busan Shinho Solar Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		25.00%		25.00%
Acquisition cost		₩ 2,100		₩ 2,100
Book value [Abstract]
Beginning balance		3,814		3,678
Dividends received		(63)		(185)
Share of income (loss)		595		321
Ending balance		4,346		3,814
Share in net assets		4,346		3,814
Total assets		47,959		47,789
Total liabilities		30,573		32,533
Net assets		17,386		15,256
Sales of JointVentures		7,984		6,770
Profit (loss) for the period of JointVentures		₩ 2,383		₩ 1,247
GS Donghae Electric Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		34.00%		34.00%
Acquisition cost		₩ 204,000		₩ 204,000
Book value [Abstract]
Beginning balance		205,948		200,379
Share of income (loss)		14,714		5,575
Others (book value)		65		(6)
Ending balance		220,727		205,948
Share in net assets		220,727		205,948
Total assets		2,179,465		1,952,297
Total liabilities		1,530,266		1,346,568
Net assets		649,199		605,729
Sales of JointVentures		351,814		19,851
Profit (loss) for the period of JointVentures		₩ 43,180		₩ 16,396
Global Trade Of Power System Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Exporting products and technology of small or medium business by proxy		Exporting products and technology of small or medium business by proxy
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 290		₩ 290
Book value [Abstract]
Beginning balance		477		426
Share of income (loss)		100		51
Ending balance		577		477
Share in net assets		577		476
Total assets		3,576		1,661
Total liabilities		1,586		18
Net assets		1,990		1,643
Others (consolidated FS)				1
Sales of JointVentures		4,079		2,667
Profit (loss) for the period of JointVentures		₩ 365		₩ 205
Expressway Solar-light Power Generation Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 1,856		₩ 1,856
Book value [Abstract]
Beginning balance		2,343		2,100
Share of income (loss)		120		243
Ending balance		2,463		2,343
Share in net assets		2,463		2,343
Total assets		19,143		20,790
Total liabilities		10,651		12,710
Net assets		8,492		8,080
Sales of JointVentures		3,018		3,395
Profit (loss) for the period of JointVentures		₩ 643		₩ 960
KODE NOVUS I LLC [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		USA		USA
Percentage of ownership		50.00%		50.00%
Acquisition cost		₩ 19,213		₩ 19,213
Book value [Abstract]
Share in net assets		(53,689)		(44,983)
Total assets		755		14,286
Total liabilities		108,132		104,252
Net assets		(107,377)		(89,966)
Investment differential				4,732
Others (consolidated FS)		53,689		40,251
Sales of JointVentures		14		2,362
Profit (loss) for the period of JointVentures		(8,117)		(50,151)
Unrecognized equity interest		8,706		22,194
Accumulated unrecognized equity interest		₩ 53,689		₩ 44,983
KODE NOVUS II LLC [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		USA		USA
Percentage of ownership		50.00%		50.00%
Acquisition cost		₩ 12,756		₩ 12,756
Book value [Abstract]
Acquisition				258
Share of income (loss)				(260)
Others (book value)				2
Share in net assets		(23,696)		(23,516)
Total assets		292		3,236
Total liabilities		47,683		50,267
Net assets		(47,391)		(47,031)
Others (consolidated FS)		23,696		23,516
Sales of JointVentures				810
Profit (loss) for the period of JointVentures		(6,018)		(22,582)
Unrecognized equity interest		181		12,340
Accumulated unrecognized equity interest		₩ 23,696		₩ 23,515
Daejung Offshore Wind Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		49.90%		49.90%
Acquisition cost		₩ 5,190		₩ 4,990
Book value [Abstract]
Beginning balance		3,015		3,352
Acquisition		200
Share of income (loss)		(246)		(337)
Ending balance		2,969		3,015
Share in net assets		2,969		3,015
Total assets		6,193		6,076
Total liabilities		243		34
Net assets		5,950		6,042
Profit (loss) for the period of JointVentures		₩ (493)		₩ (675)
Shareholders’ agreements that may cause future economic resource or cash outflows		In case Samsung Heavy Industries Co., Ltd., a co-participant of the joint venture agreement, decides to dispose of its shares in Daejung Offshore Wind Power Co., Ltd., the Company is obligated to acquire those shares after evaluating the economic feasibility of the facilities installed by Samsung Heavy Industries Co., Ltd.
Amman Asia Electric Power Company [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation		Power generation
Location	[1]	JORDAN		JORDAN
Percentage of ownership	[1]	60.00%		60.00%
Acquisition cost	[1]	₩ 111,476		₩ 111,476
Book value [Abstract]
Beginning balance		153,857	[1]	137,668
Dividends received		(12,213)		(12,684)
Share of income (loss)		19,957		17,811
Other comprehensive income (loss)		(15,925)		11,062
Ending balance	[1]	145,676		153,857
Share in net assets		145,764		153,944
Total assets		759,114		881,164
Total liabilities		516,174		624,590
Net assets		242,940		256,574
Others (consolidated FS)		(88)		(87)
Sales of JointVentures		18,034		13,631
Profit (loss) for the period of JointVentures		₩ 33,514		₩ 29,684
KAPES, Inc. (formerly, KEPCO-ALSTOM Power Electronics Systems, Inc.) [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	R&D		R&D
Location	[1]	KOREA		KOREA
Percentage of ownership	[1]	51.00%		51.00%
Acquisition cost	[1]	₩ 5,629		₩ 5,629
Book value [Abstract]
Beginning balance		4,758	[1]	4,501
Share of income (loss)		2,752		311
Others (book value)		(34)		(54)
Ending balance	[1]	7,476		4,758
Share in net assets		7,476		4,758
Total assets		70,679		145,576
Total liabilities		56,021		136,247
Net assets		14,658		9,329
Sales of JointVentures		129,962		31,852
Profit (loss) for the period of JointVentures		₩ 5,397		₩ 456
Dangjin Eco Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		34.00%		34.00%
Acquisition cost		₩ 61,540		₩ 56,100
Book value [Abstract]
Beginning balance		53,253		48,281
Acquisition		5,440		5,100
Share of income (loss)		(752)		(696)
Other comprehensive income (loss)		(3)		(26)
Others (book value)		(10)		594
Ending balance		57,928		53,253
Share in net assets		55,310		50,635
Total assets		163,197		149,926
Total liabilities		521		1,001
Net assets		162,676		148,925
Investment differential		2,618		2,618
Profit (loss) for the period of JointVentures		₩ (2,182)		₩ (2,023)
Honam Wind Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 3,480		₩ 3,480
Book value [Abstract]
Beginning balance		4,451		3,926
Dividends received		(487)		(104)
Share of income (loss)		338		629
Ending balance		4,302		4,451
Share in net assets		4,270		4,419
Total assets		39,675		41,614
Total liabilities		24,951		26,375
Net assets		14,724		15,239
Investment differential		32		32
Sales of JointVentures		5,961		6,776
Profit (loss) for the period of JointVentures		₩ 1,166		2,171
Nepal Water & Energy Development Company Private Limited [Member]
Book value [Abstract]
Beginning balance				17,765
Share of income (loss)				359
Other comprehensive income (loss)				543
Others (book value)				₩ (18,667)
Chun-cheon Energy Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.90%		29.90%
Acquisition cost		₩ 52,700		₩ 52,700
Book value [Abstract]
Beginning balance		50,592		31,976
Acquisition				19,832
Share of income (loss)		(2,474)		(1,121)
Other comprehensive income (loss)				(95)
Ending balance		48,118		50,592
Share in net assets		48,115		50,589
Total assets		699,652		548,306
Total liabilities		538,733		379,113
Net assets		160,919		169,193
Investment differential		3		3
Sales of JointVentures		164,294
Profit (loss) for the period of JointVentures		₩ (8,145)		₩ (3,684)
Yeonggwangbaeksu Wind Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[3]	Power generation		Power generation
Location	[3]	KOREA		KOREA
Percentage of ownership	[3]	15.00%		15.00%
Acquisition cost	[3]	₩ 3,000		₩ 3,000
Book value [Abstract]
Beginning balance		2,689	[3]	2,668
Share of income (loss)		45		16
Others (book value)				5
Ending balance	[3]	2,734		2,689
Share in net assets		2,728		2,684
Total assets		94,810		99,773
Total liabilities		76,621		81,881
Net assets		18,189		17,892
Investment differential		6		5
Sales of JointVentures		11,124		11,208
Profit (loss) for the period of JointVentures		₩ 297		₩ (26)
Nghi Son 2 Power Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		VIETNAM		VIETNAM
Percentage of ownership		50.00%		50.00%
Acquisition cost		₩ 2,781		₩ 1,788
Book value [Abstract]
Beginning balance		229		269
Acquisition		993		716
Share of income (loss)		(1,039)		(740)
Other comprehensive income (loss)				(16)
Ending balance		183		229
Share in net assets		183		228
Total assets		741		757
Total liabilities		376		302
Net assets		365		455
Others (consolidated FS)				1
Profit (loss) for the period of JointVentures		₩ (2,068)		₩ (1,481)
Kelar S.A [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation		Power generation
Location	[1]	CHILE		CHILE
Percentage of ownership	[1]	65.00%		65.00%
Acquisition cost	[1]	₩ 77,220		₩ 4,180
Book value [Abstract]
Acquisition		73,040
Share of income (loss)		(633)
Other comprehensive income (loss)		(5,175)
Others (book value)		1
Ending balance	[1]	67,233
Share in net assets		65,125		(61,309)
Total assets		613,293		617,803
Total liabilities		513,101		712,124
Net assets		100,192		(94,321)
Investment differential		2,424		2,424
Others (consolidated FS)		(316)		58,885
Sales of JointVentures		90,435
Profit (loss) for the period of JointVentures		17,590		(4,109)
Unrecognized equity interest		₩ (61,309)		43,920
Accumulated unrecognized equity interest				₩ 61,309
PT. Tanjung Power Indonesia [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		INDONESIA		INDONESIA
Percentage of ownership		35.00%		35.00%
Acquisition cost		₩ 746		₩ 746
Book value [Abstract]
Beginning balance		1,946		617
Share of income (loss)		2,112		1,337
Other comprehensive income (loss)		(2,281)
Others (book value)		(1)		(8)
Ending balance		1,776		1,946
Share in net assets		1,776		1,946
Total assets		374,702		203,051
Total liabilities		369,627		197,491
Net assets		5,075		5,560
Sales of JointVentures		209,923		122,583
Profit (loss) for the period of JointVentures		₩ 6,219		₩ 3,821
Incheon New Power Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 461		₩ 461
Book value [Abstract]
Beginning balance		563		514
Share of income (loss)		56		41
Other comprehensive income (loss)				8
Ending balance		619		563
Share in net assets		619		563
Total assets		7,194		7,902
Total liabilities		5,059		5,961
Net assets		2,135		1,941
Sales of JointVentures		2,972		2,985
Profit (loss) for the period of JointVentures		₩ 184		₩ 168
Seokmun Energy Co., Ltd. [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		KOREA		KOREA
Percentage of ownership		29.00%		29.00%
Acquisition cost		₩ 15,370		₩ 580
Book value [Abstract]
Beginning balance		391
Acquisition		14,790
Share of income (loss)		(1,219)		(197)
Other comprehensive income (loss)		(176)		793
Others (book value)				(205)
Ending balance		13,786		391
Share in net assets		13,786		391
Total assets		247,735		235,905
Total liabilities		200,197		234,556
Net assets		47,538		1,349
Sales of JointVentures		35,135
Profit (loss) for the period of JointVentures		₩ (3,939)		(543)
Unrecognized equity interest				₩ (205)
Daehan Wind Power PSC [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation
Location		JORDAN		JORDAN
Percentage of ownership		50.00%		50.00%
Acquisition cost		₩ 285		₩ 285
Book value [Abstract]
Beginning balance		16
Acquisition				285
Share of income (loss)		(40)		(261)
Other comprehensive income (loss)		22		(8)
Others (book value)		2
Ending balance				16
Share in net assets		(412)		18
Total assets		928		750
Total liabilities		1,752		714
Net assets		(824)		36
Others (consolidated FS)		412		(2)
Profit (loss) for the period of JointVentures		(904)		₩ (523)
Unrecognized equity interest		412
Accumulated unrecognized equity interest		₩ 412
Barakah One Company [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[4]	Power generation		Power generation
Location	[4]	UAE		UAE
Percentage of ownership	[4]	18.00%		18.00%
Acquisition cost	[4]	₩ 118		₩ 118
Book value [Abstract]
Beginning balance	[4]	116
Acquisition				118
Share of income (loss)		570
Other comprehensive income (loss)		(60)
Others (book value)				(2)
Ending balance	[4]	626		116
Share in net assets		626		118
Total assets		17,574,885		17,117,338
Total liabilities		17,571,409		17,116,680
Net assets		3,476		658
Others (consolidated FS)				₩ (2)
Profit (loss) for the period of JointVentures		₩ (1,358)
Nawah Energy Company [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[4]	Operation of utility plant		Operation of utility plant
Location	[4]	UAE		UAE
Percentage of ownership	[4]	18.00%		18.00%
Acquisition cost	[4]	₩ 296		₩ 296
Book value [Abstract]
Beginning balance	[4]	290
Acquisition				296
Share of income (loss)		(5)
Other comprehensive income (loss)		(27)
Others (book value)				(6)
Ending balance	[4]	258		290
Share in net assets		258		296
Total assets		1,459		1,645
Total liabilities		23
Net assets		1,436		1,645
Others (consolidated FS)				₩ (6)
Profit (loss) for the period of JointVentures		₩ (11)
MOMENTUM [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		International thermonuclear experimental reactor construction management		International thermonuclear experimental reactor construction management
Location		FRANCE		FRANCE
Percentage of ownership		33.33%		33.33%
Acquisition cost		₩ 1		₩ 1
Book value [Abstract]
Beginning balance		67
Acquisition				1
Share of income (loss)		321		65
Other comprehensive income (loss)		3
Others (book value)				1
Ending balance		391		67
Share in net assets		391		67
Total assets		5,028		2,749
Total liabilities		3,854		2,547
Net assets		1,174		202
Sales of JointVentures		11,555		2,886
Profit (loss) for the period of JointVentures		₩ 939		₩ 194
Daegu Green Power [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation		Power generation	[5]
Location		KOREA		KOREA	[5]
Percentage of ownership		29.00%		29.00%	[5]
Acquisition cost		₩ 46,225		₩ 46,225	[5]
Book value [Abstract]
Beginning balance	[5]	47,528
Share of income (loss)		(5,133)
Others (book value)		(4)		47,528
Ending balance		42,391		47,528	[5]
Share in net assets		20,795		25,932
Total assets		602,809		636,438
Total liabilities		531,103		547,017
Net assets		71,706		89,421
Investment differential				84
Intercompany transaction		84
Others (consolidated FS)		21,512		21,512
Sales of JointVentures		256,359		265,621
Profit (loss) for the period of JointVentures		₩ (17,700)		₩ (3,981)
Significant restrictions on its abilities		Principals on subordinated loans or dividends can only be paid when all conditions of the loan agreement are satisfied or prior written consent of financial institutions is obtained. Shares cannot be wholly or partially transferred without prior written consent of financial institutions is obtained.
Yeonggwang Wind Power Co., Ltd [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation
Location		KOREA
Percentage of ownership		41.00%
Acquisition cost		₩ 15,375
Book value [Abstract]
Acquisition		15,375
Share of income (loss)		(25)
Other comprehensive income (loss)		(56)
Ending balance		15,294
Share in net assets		15,063
Total assets		212,802
Total liabilities		176,062
Net assets		36,740
Investment differential		231
Profit (loss) for the period of JointVentures		₩ (62)
Chester Solar IV SpA [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation
Location	[1]	CHILE
Percentage of ownership	[1]	81.82%
Acquisition cost	[1]	₩ 1,700
Book value [Abstract]
Acquisition		1,700
Ending balance	[1]	1,700
Share in net assets		1,664
Total assets		11,660
Total liabilities		9,626
Net assets		2,034
Others (consolidated FS)		36
Sales of JointVentures		331
Profit (loss) for the period of JointVentures		₩ 151
Chester Solar V SpA [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation
Location	[1]	CHILE
Percentage of ownership	[1]	81.82%
Acquisition cost	[1]	₩ 525
Book value [Abstract]
Acquisition		525
Ending balance	[1]	525
Share in net assets		419
Total assets		2,081
Total liabilities		1,569
Net assets		512
Others (consolidated FS)		106
Profit (loss) for the period of JointVentures		₩ (49)
Diego de Almagro Solar SpA [Member]
Disclosure of joint ventures [Line Items]
Key operation activities	[1]	Power generation
Location	[1]	CHILE
Percentage of ownership	[1]	81.82%
Acquisition cost	[1]	₩ 2,091
Book value [Abstract]
Acquisition		2,091
Ending balance	[1]	2,091
Share in net assets		1,993
Total assets		8,266
Total liabilities		5,830
Net assets		2,436
Others (consolidated FS)		98
Profit (loss) for the period of JointVentures		₩ (103)
South Jamaica Power Company Limited [Member]
Disclosure of joint ventures [Line Items]
Key operation activities		Power generation
Location		JAMAICA
Percentage of ownership		20.00%
Acquisition cost		₩ 7,090
Book value [Abstract]
Acquisition		7,090
Others (book value)		(386)
Ending balance		6,704
Share in net assets		6,704
Total assets		153,958
Total liabilities		120,436
Net assets		33,522
Profit (loss) for the period of JointVentures		₩ (755)
[1]	According to the shareholders’ agreement, all critical financial and operating decisions must be agreed to by all ownership parties. For these reasons, the entities are classified as joint ventures.
[2]	The Company has joint control over the entity by virtue of its contractual right to appoint directors to the board of directors of the entity, and by strict decision criteria of the Company’s financial and operating policy of the board of directors.
[3]	The Company can exercise significant influence by virtue of its contractual right to appoint a director to the board of directors of the entity.
[4]	The effective percentage of ownership is less than 20% but the Company has joint control over the entity as decisions on the major activities require the unanimous consent of the parties that collectively control the entity.
[5]	The entity is reclassified from associates to joint ventures since the terms of the shareholders’ agreement had been amended.

Property, Plant and Equipmen148

Property, Plant and Equipment (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in property and equipment [Line Items]
Beginning balance		₩ 145,743,056
Impairment		51,067		₩ 30,344
Ending balance		150,882,414	₩ 145,743,056
Land [Member]
Changes in property and equipment [Line Items]
Beginning balance		12,966,537	12,393,313
Ending balance		13,296,574	12,966,537	12,393,313
Land [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		12,969,741	12,396,460
Acquisitions		32,773	13,973
Disposals		(8,961)	(52,569)
Others		324,989	611,877
Ending balance		13,318,542	12,969,741	12,396,460
Land [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		12,969,741	12,396,460
Ending balance		13,318,542	12,969,741	12,396,460
Land [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(3,204)	(3,147)
Disposals		5	14
Others		(18,769)	(71)
Ending balance		(21,968)	(3,204)	(3,147)
Buildings [Member]
Changes in property and equipment [Line Items]
Beginning balance		11,723,436	9,612,500
Ending balance		11,989,987	11,723,436	9,612,500
Buildings [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		11,784,624	9,676,432
Acquisitions		40,592
Disposals		(19,715)	(9,020)
Depreciation		(794,804)	(676,866)
Impairment	[1]	(923)
Others		1,043,752	2,794,078
Ending balance		12,053,526	11,784,624	9,676,432
Buildings [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		17,722,326	14,936,722
Ending balance		18,777,678	17,722,326	14,936,722
Buildings [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(5,936,849)	(5,259,436)
Ending balance		(6,722,376)	(5,936,849)	(5,259,436)
Buildings [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Beginning balance		(853)	(854)
Ending balance		(1,776)	(853)	(854)
Buildings [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(61,188)	(63,932)
Acquisitions		(900)
Disposals		28	731
Depreciation		5,996	5,299
Others		(7,475)	(3,286)
Ending balance		(63,539)	(61,188)	(63,932)
Structures [Member]
Changes in property and equipment [Line Items]
Beginning balance		43,132,774	40,065,043
Ending balance		43,908,364	43,132,774	40,065,043
Structures [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		43,330,415	40,258,162
Acquisitions		428	455
Disposals		(519,366)	(524,310)
Depreciation		(2,421,168)	(2,233,333)
Impairment	[1]	(6,856)
Others		3,721,325	5,829,441
Ending balance		44,104,778	43,330,415	40,258,162
Structures [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		63,291,437	58,251,296
Ending balance		66,184,484	63,291,437	58,251,296
Structures [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(19,959,839)	(17,991,950)
Ending balance		(22,071,667)	(19,959,839)	(17,991,950)
Structures [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Beginning balance		(1,183)	(1,184)
Ending balance		(8,039)	(1,183)	(1,184)
Structures [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(197,641)	(193,119)
Disposals		1,905	2,597
Depreciation		10,011	9,491
Others		(10,689)	(16,610)
Ending balance		(196,414)	(197,641)	(193,119)
Machinery [Member]
Changes in property and equipment [Line Items]
Beginning balance		43,310,881	36,755,814
Ending balance		46,692,610	43,310,881	36,755,814
Machinery [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		43,421,945	36,864,749
Acquisitions		421,892	193,017
Disposals		(242,428)	(243,757)
Depreciation		(4,821,595)	(4,353,596)
Impairment	[1]	(43,121)
Others		8,139,105	10,961,532
Ending balance		46,875,798	43,421,945	36,864,749
Machinery [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		67,769,168	57,143,211
Ending balance		75,826,292	67,769,168	57,143,211
Machinery [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(24,344,832)	(20,242,232)
Ending balance		(28,904,982)	(24,344,832)	(20,242,232)
Machinery [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Beginning balance		(2,391)	(36,230)
Ending balance		(45,512)	(2,391)	(36,230)
Machinery [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(111,064)	(108,935)
Acquisitions		(10,834)	(33)
Disposals		489	1,210
Depreciation		17,390	12,272
Others		(79,169)	(15,578)
Ending balance		(183,188)	(111,064)	(108,935)
Ships [Member]
Changes in property and equipment [Line Items]
Beginning balance		550	786
Ending balance		403	550	786
Ships [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		550	786
Depreciation		(147)	(281)
Others			45
Ending balance		403	550	786
Ships [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		4,175	4,930
Ending balance		4,175	4,175	4,930
Ships [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(3,625)	(4,144)
Ending balance		(3,772)	(3,625)	(4,144)
Vehicles [Member]
Changes in property and equipment [Line Items]
Beginning balance		70,863	60,443
Ending balance		74,716	70,863	60,443
Vehicles [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		70,970	60,472
Acquisitions		3,447	2,493
Disposals		(174)	(34)
Depreciation		(34,236)	(27,615)
Impairment	[1]	(127)
Others		41,158	35,654
Ending balance		81,038	70,970	60,472
Vehicles [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		247,751	227,733
Ending balance		276,425	247,751	227,733
Vehicles [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(176,781)	(167,261)
Ending balance		(195,260)	(176,781)	(167,261)
Vehicles [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Ending balance		(127)
Vehicles [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(107)	(29)
Acquisitions		(107)	(58)
Disposals		14
Depreciation		1,070	25
Others		(7,192)	(45)
Ending balance		(6,322)	(107)	(29)
Equipment [Member]
Changes in property and equipment [Line Items]
Beginning balance		375,663	309,545
Ending balance		419,911	375,663	309,545
Equipment [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		376,395	310,571
Acquisitions		53,529	67,134
Disposals		(413)	(323)
Depreciation		(158,614)	(128,084)
Impairment	[1]	(6)
Others		149,781	127,097
Ending balance		420,672	376,395	310,571
Equipment [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		1,270,660	1,134,376
Ending balance		1,440,870	1,270,660	1,134,376
Equipment [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(894,265)	(823,805)
Ending balance		(1,020,192)	(894,265)	(823,805)
Equipment [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Ending balance		(6)
Equipment [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(732)	(1,026)
Acquisitions		(43)
Depreciation		454	452
Others		(440)	(158)
Ending balance		(761)	(732)	(1,026)
Tools [Member]
Changes in property and equipment [Line Items]
Beginning balance		178,602	159,939
Ending balance		199,636	178,602	159,939
Tools [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		179,032	160,630
Acquisitions		30,990	27,856
Disposals		(166)	(327)
Depreciation		(74,909)	(69,842)
Impairment	[1]	(32)
Others		65,748	60,715
Ending balance		200,663	179,032	160,630
Tools [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		921,115	836,131
Ending balance		1,010,537	921,115	836,131
Tools [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(742,083)	(675,501)
Ending balance		(809,842)	(742,083)	(675,501)
Tools [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Ending balance		(32)
Tools [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(430)	(691)
Depreciation		354	295
Others		(951)	(34)
Ending balance		(1,027)	(430)	(691)
Construction in progress [Member]
Changes in property and equipment [Line Items]
Beginning balance		27,160,453	35,127,128
Ending balance		25,523,457	27,160,453	35,127,128
Construction in progress [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		27,296,260	35,267,026
Acquisitions		11,996,508	11,752,352
Disposals		(6,487)	(94,443)
Others		(13,713,740)	(19,628,675)
Ending balance		25,572,541	27,296,260	35,267,026
Construction in progress [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		27,334,368	35,305,133
Ending balance		25,610,649	27,334,368	35,305,133
Construction in progress [Member] | Accumulated impairment losses [Member]
Changes in property and equipment [Line Items]
Beginning balance		(38,108)	(38,107)
Ending balance		(38,108)	(38,108)	(38,107)
Construction in progress [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		(135,807)	(139,898)
Acquisitions		(42,728)	(28,434)
Others		129,451	32,525
Ending balance		(49,084)	(135,807)	(139,898)
Finance lease assets [Member]
Changes in property and equipment [Line Items]
Beginning balance		406,353	511,509
Ending balance		297,652	406,353	511,509
Finance lease assets [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		406,353	511,509
Acquisitions			34
Disposals		(29,696)	(31)
Depreciation		(107,390)	(96,254)
Others		28,412	(8,905)
Ending balance		297,679	406,353	511,509
Finance lease assets [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		2,390,779	2,389,985
Ending balance		2,390,680	2,390,779	2,389,985
Finance lease assets [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(1,984,426)	(1,878,476)
Ending balance		(2,093,001)	(1,984,426)	(1,878,476)
Finance lease assets [Member] | Government grants [Member]
Changes in property and equipment [Line Items]
Depreciation		1
Others		(28)
Ending balance		(27)
Retirements, property, plant and equipment [Member]
Changes in property and equipment [Line Items]
Beginning balance		4,065,412	4,106,087
Ending balance		6,039,484	4,065,412	4,106,087
Retirements, property, plant and equipment [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		4,065,412	4,106,087
Depreciation		(518,565)	(509,310)
Others		2,492,637	468,635
Ending balance		6,039,484	4,065,412	4,106,087
Retirements, property, plant and equipment [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		7,129,771	6,888,547
Ending balance		9,395,821	7,129,771	6,888,547
Retirements, property, plant and equipment [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(3,064,359)	(2,782,460)
Ending balance		(3,356,337)	(3,064,359)	(2,782,460)
Other property, plant and equipment [Member]
Changes in property and equipment [Line Items]
Beginning balance		2,351,532	2,259,244
Ending balance		2,439,620	2,351,532	2,259,244
Other property, plant and equipment [Member] | Carrying Amount Other than Government Grants [Member]
Changes in property and equipment [Line Items]
Beginning balance		2,351,532	2,259,244
Acquisitions		10,411
Disposals		(28)	(9)
Depreciation		(762,711)	(813,248)
Others		840,416	905,545
Ending balance		2,439,620	2,351,532	2,259,244
Other property, plant and equipment [Member] | Acquisition cost [Member]
Changes in property and equipment [Line Items]
Beginning balance		10,361,294	9,438,381
Ending balance		11,247,021	10,361,294	9,438,381
Other property, plant and equipment [Member] | Accumulated depreciation [Member]
Changes in property and equipment [Line Items]
Beginning balance		(8,009,762)	(7,179,137)
Ending balance		₩ (8,807,401)	₩ (8,009,762)	₩ (7,179,137)
[1]	Korea Midland Power Co., Ltd. and Korea Western Power Co., Ltd., 100% owned subsidiaries, have determined that there are impairment indicators for the shutdowns of certain power generation units and fire, and performed an impairment test over the individual assets. As a result, the Company recognized the amount of the carrying amount in excess of its recoverable amount as impairment loss in the consolidated statements of comprehensive income.

Investment properties, net (Det

Investment properties, net (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about investment property [Line Items]
Beginning balance	₩ 353,680	₩ 269,910
Depreciation	(1,176)	(678)	₩ (669)
Others	(67,790)	84,448
Endings balance	284,714	353,680	269,910
Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	353,744	269,923
Depreciation	(1,178)	(679)
Others	(67,769)	84,500
Endings balance	284,797	353,744	269,923
Acquisition cost [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	365,589
Endings balance	300,370	365,589
Accumulated depreciation [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	(11,845)
Endings balance	(15,573)	(11,845)
Government grants [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	(64)	(13)
Depreciation	2	1
Others	(21)	(52)
Endings balance	(83)	(64)	(13)
Investment property - Land [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	336,421	253,960
Depreciation	0	0
Others	(72,216)	82,461
Endings balance	264,205	336,421	253,960
Investment property - Land [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	336,421	253,960
Others	(72,216)	82,461
Endings balance	264,205	336,421	253,960
Investment property - Land [Member] | Acquisition cost [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	336,421
Endings balance	264,205	336,421
Investment property - Buildings [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	17,259	15,950
Depreciation	(1,176)	(678)
Others	4,426	1,987
Endings balance	20,509	17,259	15,950
Investment property - Buildings [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	17,323	15,963
Depreciation	(1,178)	(679)
Others	4,447	2,039
Endings balance	20,592	17,323	15,963
Investment property - Buildings [Member] | Acquisition cost [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	29,168
Endings balance	36,165	29,168
Investment property - Buildings [Member] | Accumulated depreciation [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	(11,845)
Endings balance	(15,573)	(11,845)
Investment property - Buildings [Member] | Government grants [Member]
Disclosure of detailed information about investment property [Line Items]
Beginning balance	(64)	(13)
Depreciation	2	1
Others	(21)	(52)
Endings balance	₩ (83)	₩ (64)	₩ (13)

Income and expenses on investme

Income and expenses on investment property (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income and expenses on investment property [Abstract]
Rental income	₩ 9,581	₩ 9,460
Operating and maintenance expenses related to rental income	(1,172)	(678)
Rental income from investment property, net of direct operating expense	₩ 8,409	₩ 8,782

The fair value of investment pr

The fair value of investment property (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - The fair value of investment property [Line Items]
Fair value of Investment property	₩ 332,560	₩ 394,750
Carrying amount of Investment property	284,714	353,680	₩ 269,910
Land [Member]
Disclosure - The fair value of investment property [Line Items]
Fair value of Investment property	309,241	374,042
Carrying amount of Investment property	264,205	336,421	253,960
Buildings [Member]
Disclosure - The fair value of investment property [Line Items]
Fair value of Investment property	23,319	20,708
Carrying amount of Investment property	₩ 20,509	₩ 17,259	₩ 15,950

Construction Services Contra152

Construction Services Contracts (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Construction Services Contracts [Abstract]
Beginning balance	₩ 7,236,888		₩ 12,308,839		₩ 17,081,074
Increase and decrease [Abstract]
New orders and other	(438,142)		(718,118)		(412,617)
Changes in scope of construction work	286,251		1,763,212		1,423,648
Increase (decrease) in Construction contracts	151,891	[1]	(1,045,094)	[2]	(1,011,031)	[3]
Recognized as revenue	(3,212,184)		(4,026,857)		(3,761,204)
Ending balance	₩ 4,176,595		₩ 7,236,888		₩ 12,308,839
[1]	For the year ended December 31, 2017, the increased balance of contracts from new orders and other is ￦438,142 million and the decreased balance of contracts due to changes in scope of construction work is ￦286,251 million.
[2]	For the year ended December 31, 2016, the increased balance of contracts from new orders and other is ￦718,118 million and the decreased balance of contracts due to changes in scope of construction work is ￦1,763,212 million.
[3]	For the year ended December 31, 2015, the increased balance of contracts from new orders and other is ￦412,617 million and the decreased balance of contracts due to changes in scope of construction work is ￦1,423,648 million.

Construction Services Contra153

Construction Services Contracts, Continued (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Accumulated earned revenue, expense and others [Abstract]
Accumulated earned revenue		₩ 18,236,992	₩ 15,314,737
Accumulated expense		16,937,772	14,396,890
Accumulated profit		1,299,220	917,847
Unearned advance receipts		0	0
Contract with Customer, Asset and Liability [Abstract]
Assets	[1]	55,755	44,930
Liabilities	[2]	₩ 542,921	₩ 651,985
[1]	Included in trade and other receivables, net, in the consolidated statements of financial position.
[2]	Included in non-financial liabilities in the consolidated statements of financial position.

Detailed information about inta

Detailed information about intangible assets (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	₩ 1,187,121	₩ 980,821
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	980,821
Changes in intangible assets other than goodwill [Abstract]
Impairment loss	20	3,945	₩ 22
Ending balance	1,187,121	980,821
Intangible assets other than goodwill [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	1,187,121	980,821	855,832
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	980,821	855,832
Changes in intangible assets other than goodwill [Abstract]
Acquisition	143,887	124,422
Disposal	(661)	(589)
Amortization	(113,672)	(79,715)
Impairment loss	34	(3,942)
Others	176,712	84,813
Ending balance	1,187,121	980,821	855,832
Intangible assets other than goodwill [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	1,201,860	997,679	873,882
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	997,679	873,882
Changes in intangible assets other than goodwill [Abstract]
Acquisition	143,904	126,019
Disposal	(661)	(589)
Amortization	(116,748)	(82,747)
Impairment loss	34	(3,942)
Others	177,652	85,056
Ending balance	1,201,860	997,679	873,882
Intangible assets other than goodwill [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	2,897,446	2,581,539
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	2,581,539
Changes in intangible assets other than goodwill [Abstract]
Ending balance	2,897,446	2,581,539
Intangible assets other than goodwill [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(1,679,576)	(1,567,795)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(1,567,795)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(1,679,576)	(1,567,795)
Intangible assets other than goodwill [Member] | Accumulated impairment [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(16,010)	(16,065)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(16,065)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(16,010)	(16,065)
Intangible assets other than goodwill [Member] | Government grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(14,739)	(16,858)	(18,050)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(16,858)	(18,050)
Changes in intangible assets other than goodwill [Abstract]
Acquisition	(17)	(1,597)
Amortization	3,076	3,032
Others	(940)	(243)
Ending balance	(14,739)	(16,858)	(18,050)
Software [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	125,405	92,626	57,187
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	92,626	57,187
Changes in intangible assets other than goodwill [Abstract]
Acquisition	12,683	18,267
Disposal	(5)
Amortization	(44,554)	(32,129)
Others	64,655	49,301
Ending balance	125,405	92,626	57,187
Software [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	125,891	93,221	57,886
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	93,221	57,886
Changes in intangible assets other than goodwill [Abstract]
Acquisition	12,700	18,267
Disposal	(5)
Amortization	(44,809)	(32,378)
Others	64,784	49,446
Ending balance	125,891	93,221	57,886
Software [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	534,191	458,382
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	458,382
Changes in intangible assets other than goodwill [Abstract]
Ending balance	534,191	458,382
Software [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(408,300)	(365,161)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(365,161)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(408,300)	(365,161)
Software [Member] | Government grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(486)	(595)	(699)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(595)	(699)
Changes in intangible assets other than goodwill [Abstract]
Acquisition	(17)
Amortization	255	249
Others	(129)	(145)
Ending balance	(486)	(595)	(699)
Licences and franchises [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	3,398	3,398
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	3,398
Changes in intangible assets other than goodwill [Abstract]
Ending balance	3,398	3,398
Licences and franchises [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(3,398)	(3,398)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(3,398)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(3,398)	(3,398)
Copyrights, patents rights and other industrial rights [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	23,981	20,081	21,875
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	20,081	21,875
Changes in intangible assets other than goodwill [Abstract]
Acquisition	30	85
Disposal	(7)	(39)
Amortization	(3,350)	(2,697)
Others	7,227	857
Ending balance	23,981	20,081	21,875
Copyrights, patents rights and other industrial rights [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	23,981	20,081	21,875
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	20,081	21,875
Changes in intangible assets other than goodwill [Abstract]
Acquisition	30	85
Disposal	(7)	(39)
Amortization	(3,350)	(2,697)
Others	7,227	857
Ending balance	23,981	20,081	21,875
Copyrights, patents rights and other industrial rights [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	43,857	35,756
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	35,756
Changes in intangible assets other than goodwill [Abstract]
Ending balance	43,857	35,756
Copyrights, patents rights and other industrial rights [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(19,876)	(15,675)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(15,675)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(19,876)	(15,675)
Mining rights [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	539,633	538,860	499,537
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	538,860	499,537
Changes in intangible assets other than goodwill [Abstract]
Acquisition	26,751	26,311
Disposal	(272)
Amortization	(4,640)	(899)
Others	(21,066)	13,911
Ending balance	539,633	538,860	499,537
Mining rights [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	539,633	538,860	499,537
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	538,860	499,537
Changes in intangible assets other than goodwill [Abstract]
Acquisition	26,751	26,311
Disposal	(272)
Amortization	(4,640)	(899)
Others	(21,066)	13,911
Ending balance	539,633	538,860	499,537
Mining rights [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	553,876	549,371
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	549,371
Changes in intangible assets other than goodwill [Abstract]
Ending balance	553,876	549,371
Mining rights [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(14,243)	(10,511)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(10,511)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(14,243)	(10,511)
Development expenditures [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	80,816	57,253	44,972
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	57,253	44,972
Changes in intangible assets other than goodwill [Abstract]
Acquisition	494	212
Amortization	(23,113)	(19,222)
Others	46,182	31,291
Ending balance	80,816	57,253	44,972
Development expenditures [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	84,518	62,405	51,807
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	62,405	51,807
Changes in intangible assets other than goodwill [Abstract]
Acquisition	494	212
Amortization	(25,924)	(21,993)
Others	47,543	32,379
Ending balance	84,518	62,405	51,807
Development expenditures [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	836,996	785,966
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	785,966
Changes in intangible assets other than goodwill [Abstract]
Ending balance	836,996	785,966
Development expenditures [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(752,478)	(723,561)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(723,561)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(752,478)	(723,561)
Development expenditures [Member] | Government grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(3,702)	(5,152)	(6,835)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(5,152)	(6,835)
Changes in intangible assets other than goodwill [Abstract]
Amortization	2,811	2,771
Others	(1,361)	(1,088)
Ending balance	(3,702)	(5,152)	(6,835)
Intangible assets under development [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	129,370	104,443	84,403
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	104,443	84,403
Changes in intangible assets other than goodwill [Abstract]
Acquisition	56,527	64,991
Impairment loss	(20)	(3,945)
Others	(31,580)	(41,006)
Ending balance	129,370	104,443	84,403
Intangible assets under development [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	139,910	115,533	94,886
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	115,533	94,886
Changes in intangible assets other than goodwill [Abstract]
Acquisition	56,527	66,588
Impairment loss	(20)	(3,945)
Others	(32,130)	(41,996)
Ending balance	139,910	115,533	94,886
Intangible assets under development [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	143,851	119,474
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	119,474
Changes in intangible assets other than goodwill [Abstract]
Ending balance	143,851	119,474
Intangible assets under development [Member] | Accumulated impairment [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(3,941)	(3,941)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(3,941)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(3,941)	(3,941)
Intangible assets under development [Member] | Government grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(10,540)	(11,090)	(10,483)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(11,090)	(10,483)
Changes in intangible assets other than goodwill [Abstract]
Acquisition		(1,597)
Others	550	990
Ending balance	(10,540)	(11,090)	(10,483)
Usage rights of donated assets and other [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	101,647	84,081	48,559
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	84,081	48,559
Changes in intangible assets other than goodwill [Abstract]
Amortization	(14,452)	(15,502)
Others	32,018	51,024
Ending balance	101,647	84,081	48,559
Usage rights of donated assets and other [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	101,658	84,102	48,591
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	84,102	48,591
Changes in intangible assets other than goodwill [Abstract]
Amortization	(14,462)	(15,513)
Others	32,018	51,024
Ending balance	101,658	84,102	48,591
Usage rights of donated assets and other [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	459,682	426,346
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	426,346
Changes in intangible assets other than goodwill [Abstract]
Ending balance	459,682	426,346
Usage rights of donated assets and other [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(358,024)	(342,244)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(342,244)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(358,024)	(342,244)
Usage rights of donated assets and other [Member] | Government grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(11)	(21)	(32)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(21)	(32)
Changes in intangible assets other than goodwill [Abstract]
Amortization	10	11
Ending balance	(11)	(21)	(32)
Leasehold rights [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	5,044	4,632	745
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	4,632	745
Changes in intangible assets other than goodwill [Abstract]
Amortization	(545)	(351)
Others	957	4,238
Ending balance	5,044	4,632	745
Leasehold rights [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	5,044	4,632	745
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	4,632	745
Changes in intangible assets other than goodwill [Abstract]
Amortization	(545)	(351)
Others	957	4,238
Ending balance	5,044	4,632	745
Leasehold rights [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	24,306	23,350
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	23,350
Changes in intangible assets other than goodwill [Abstract]
Ending balance	24,306	23,350
Leasehold rights [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(19,262)	(18,718)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(18,718)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(19,262)	(18,718)
Greenhouse gas emissions rights [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	6,283	6,283	805
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	6,283	805
Changes in intangible assets other than goodwill [Abstract]
Acquisition		6,283
Others	(6,283)	(805)
Ending balance		6,283	805
Greenhouse gas emissions rights [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	6,283	6,283	805
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	6,283	805
Changes in intangible assets other than goodwill [Abstract]
Acquisition		6,283
Others	(6,283)	(805)
Ending balance		6,283	805
Greenhouse gas emissions rights [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	6,283	6,283
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	6,283
Changes in intangible assets other than goodwill [Abstract]
Ending balance		6,283
Others [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	181,225	72,562	97,749
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	72,562	97,749
Changes in intangible assets other than goodwill [Abstract]
Acquisition	47,402	8,273
Disposal	(377)	(550)
Amortization	(23,018)	(8,915)
Impairment loss	54	3
Others	84,602	(23,998)
Ending balance	181,225	72,562	97,749
Others [Member] | Carrying Amount Other than Government Grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	181,225	72,562	97,750
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	72,562	97,750
Changes in intangible assets other than goodwill [Abstract]
Acquisition	47,402	8,273
Disposal	(377)	(550)
Amortization	(23,018)	(8,916)
Impairment loss	54	3
Others	84,602	(23,998)
Ending balance	181,225	72,562	97,750
Others [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	297,289	173,213
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	173,213
Changes in intangible assets other than goodwill [Abstract]
Ending balance	297,289	173,213
Others [Member] | Accumulated amortization [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(103,995)	(88,527)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(88,527)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(103,995)	(88,527)
Others [Member] | Accumulated impairment [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	(12,069)	(12,124)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	(12,124)
Changes in intangible assets other than goodwill [Abstract]
Ending balance	(12,069)	(12,124)
Others [Member] | Government grants [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value		(1)	(1)
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance		(1)
Changes in intangible assets other than goodwill [Abstract]
Amortization		1
Ending balance			₩ (1)
Goodwill [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	2,582	2,582
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	2,582
Changes in intangible assets other than goodwill [Abstract]
Ending balance	2,582	2,582
Goodwill [Member] | Acquisition cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net carrying value	2,582	2,582
Reconciliation of changes in intangible assets other than goodwill [Abstract]
Beginning balance	2,582
Changes in intangible assets other than goodwill [Abstract]
Ending balance	₩ 2,582	₩ 2,582

Intangible Assets other than155

Intangible Assets other than Goodwill (Details) $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)		Dec. 31, 2016KRW (₩)		Dec. 31, 2017AUD ($)	Dec. 31, 2016AUD ($)
ERP system and others [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 1,135		₩ 506
Remaining amortisation period of intangible assets material to entity	3 years and 2 months ~ 3 years and 4 months		11 months ~ 1 year and 11 months
SCADA O/S (POWERON RELIANCE) [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value			₩ 4,206
Remaining amortisation period of intangible assets material to entity			3 years and 1 month
AMI GATEWAY S/W [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 3,528
Remaining amortisation period of intangible assets material to entity	3 years and 2 months
Smart technology verification and standard design project conducting right [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 11,724		₩ 5,750
Remaining amortisation period of intangible assets material to entity	4 years and 9 months		5 years and 9 months
Mining right of Bylong mine [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value | $					$ 401,225	$ 401,225
Remaining amortisation period of intangible assets material to entity	Mining rights are amortized using the units-of-production method and the amortization has not commenced yet.	[1]	Mining rights are amortized using the units-of-production method and the amortization has not commenced yet.	[2]
Development of maintenance system for utility plant [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value			₩ 518
Remaining amortisation period of intangible assets material to entity			11 months
Electricity sales information system [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 29,391
Remaining amortisation period of intangible assets material to entity	4 years 3 months
Contributions to ARP NRC DC [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 46,458		₩ 41,190
Remaining amortisation period of intangible assets material to entity	-		-
Dangjin power plant load facility usage right [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 20,463		₩ 26,759
Remaining amortisation period of intangible assets material to entity	3 years 3 months		4 years and 3 months
Sejong Haengbogdosi sharing charge [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 40,460		₩ 44,502
Remaining amortisation period of intangible assets material to entity	8 years and 11 months		9 years and 11 months
Occupancy and use of public waters [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value	₩ 103,269
Remaining amortisation period of intangible assets material to entity	18 years 11 months
Sillim electricity supply facility usage right [Member]
Disclosure of intangible assets material to entity [Line Items]
Carrying value			₩ 2,196
Remaining amortisation period of intangible assets material to entity			4 years and 11 months
[1]	Mining rights are amortized using the units-of-production method and the amortization has not commenced yet.
[2]	Mining rights are amortized using the units-of-production method and the amortization has not commenced yet.

Research and development expens

Research and development expenses (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Research and Development Expense [Abstract]
Research and development expense	₩ 721,437	₩ 705,504	₩ 611,220

Trade and Other Payables (Detai

Trade and Other Payables (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trade and other payables [Line Items]
Trade payables	₩ 2,936,990	₩ 2,610,373
Other trade payables	4,474,972	4,532,362
Accrued expenses	1,089,795	1,155,094
Leasehold deposits received	2,870	2,434
Other deposits received	289,713	291,462
Finance lease liabilities	418,260	541,179
Dividends payable	4,448	3,204
Others	5,953	7,478
Total trade and other payables	9,223,001	9,143,586
Current trade and other payables [Member]
Trade and other payables [Line Items]
Trade payables	2,936,990	2,610,373
Other trade payables	1,649,933	1,498,582
Accrued expenses	1,087,844	1,152,933
Leasehold deposits received	1,562	1,426
Other deposits received	186,817	197,711
Finance lease liabilities	131,792	121,176
Dividends payable	4,448	3,204
Others	135	6
Total trade and other payables	5,999,521	5,585,411
Non-current trade and other payables [Member]
Trade and other payables [Line Items]
Other trade payables	2,825,039	3,033,780
Accrued expenses	1,951	2,161
Leasehold deposits received	1,308	1,008
Other deposits received	102,896	93,751
Finance lease liabilities	286,468	420,003
Others	5,818	7,472
Total trade and other payables	₩ 3,223,480	₩ 3,558,175

Trade and Other Payables _ Liqu

Trade and Other Payables : Liquidity classification (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Trade and other payables Others [Line Items]
Total others	₩ 5,953	₩ 7,478
Other Current Liabilities [Member]
Trade and other payables Others [Line Items]
Others	135	6
Total others	135	6
Other Noncurrent Liabilities [Member]
Trade and other payables Others [Line Items]
Advance received from local governments	5,818	7,472
Total others	₩ 5,818	₩ 7,472

Borrowings and Debt Securiti159

Borrowings and Debt Securities (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Current Borrowings and Debt Securities [Abstract]
Short-term borrowings		₩ 1,038,328	₩ 805,523
Current portion of long-term borrowings		128,543	310,977
Current portion of debt securities		7,961,182	7,825,310
Less : Current portion of discount on long-term borrowings		(886)	(979)
Less : Current portion of discount on debt securities		(3,882)	(1,753)
Current Borrowings and Debt Securities		9,123,285	8,939,078
Non-current Borrowings and Debt Securities [Abstract]
Long-term borrowings		2,455,737	1,799,750
Debt securities		43,270,825	43,012,960
Less : Discount on long-term borrowings		(21,113)	(25,859)
Less : Discount on debt securities		(81,424)	(86,880)
Add : Premium on debt securities		82	156
Non-current Borrowings and Debt Securities		45,624,107	44,700,127
Total	₩ 53,639,205	₩ 54,747,392	₩ 53,639,205
Changes in borrowings and debt securities [Abstract]
Beginning balance	53,639,205
Cash flow	2,269,513
Effect of exchange rate fluctuations	(1,169,418)
Others	8,092
Ending balance	₩ 54,747,392

Borrowings and Debt Securiti160

Borrowings and Debt Securities - Repayment schedule of borrowings and debt securities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Repayment schedule of borrowings and debt securities [Line Items]
Borrowings	₩ 3,622,608	₩ 2,916,250
Debt Securities	51,232,007	50,838,270
Less than 1 year [Member]
Repayment schedule of borrowings and debt securities [Line Items]
Borrowings	1,166,871	1,116,500
Debt Securities	7,961,182	7,825,310
1~5 Years [Member]
Repayment schedule of borrowings and debt securities [Line Items]
Borrowings	1,117,222	295,162
Debt Securities	25,047,075	24,462,410
Over 5 Years [Member]
Repayment schedule of borrowings and debt securities [Line Items]
Borrowings	1,338,515	1,504,588
Debt Securities	₩ 18,223,750	₩ 18,550,550

Borrowings and Debt Securiti161

Borrowings and Debt Securities : Short-term borrowings (Details) $ in Thousands, $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)	Dec. 31, 2016KRW (₩)	Dec. 31, 2017USD ($)	Dec. 31, 2017AUD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2016AUD ($)
Disclosure of detailed information about Short-term borrowings [Line Items]
Short-term borrowings	₩ 1,038,328	₩ 805,523
Local short-term borrowings 1 [Member]
Disclosure of detailed information about Short-term borrowings [Line Items]
Name of Creditor		Woori Investment Bank and others
Borrowings interest rate		1.54~2.51
Borrowings, maturity		2017.01.25~2017.09.13
Short-term borrowings		₩ 436,800
Local short-term borrowings 2 [Member]
Disclosure of detailed information about Short-term borrowings [Line Items]
Name of Creditor	KTB Investment and securities and others
Borrowings interest rate	1.57~2.47
Borrowings, maturity	2018.01.12~ 2018.09.19
Short-term borrowings	₩ 686,561
Foreign short-term borrowings 1 [Member]
Disclosure of detailed information about Short-term borrowings [Line Items]
Name of Creditor	SCNT and others	SCNT and others
Borrowings interest rate	4.60~6.50	1.58~6.50
Borrowings, maturity	2018.12.03	2017.03.30~2017.12.03
Short-term borrowings	₩ 9,594	₩ 42,401	$ 8,955		$ 35,086
Foreign short-term borrowings 2 [Member]
Disclosure of detailed information about Short-term borrowings [Line Items]
Name of Creditor	Export-import Bank of Korea	Export-import Bank of Korea
Borrowings interest rate	3M Libor+0.41~0.63	3M Libor+0.54~0.63
Borrowings, maturity	2018.12.18	2017.05.17~2017.12.18
Short-term borrowings	₩ 273,314	₩ 271,360		$ 327,259		$ 311,174
Local bank overdraft 1 [Member]
Disclosure of detailed information about Short-term borrowings [Line Items]
Name of Creditor	Nonghyup Bank	Nonghyup Bank
Borrowings interest rate	3.04	2.45
Borrowings, maturity	2018.01.02	2017.01.05
Short-term borrowings	₩ 51,300	₩ 37,000
Local bank overdraft 2 [Member]
Disclosure of detailed information about Short-term borrowings [Line Items]
Name of Creditor	Woori Bank	Woori Bank
Borrowings interest rate	Standard overdraft rate+1.12	Standard overdraft rate+1.12
Borrowings, maturity	2018.02.27	2017.02.25
Short-term borrowings	₩ 17,559	₩ 17,962

Borrowings and Debt Securiti162

Borrowings and Debt Securities : Long-term borrowings (Details) ₨ in Thousands, ¥ in Thousands, Rp in Thousands, JD in Thousands, $ in Thousands, ₩ in Millions

12 Months Ended

Dec. 31, 2017KRW (₩)

Dec. 31, 2016KRW (₩)

Dec. 31, 2017JPY (¥)

Dec. 31, 2017USD ($)

Dec. 31, 2017JOD (JD)

Dec. 31, 2017IDR (Rp)

Dec. 31, 2017PKR (₨)

Dec. 31, 2016JPY (¥)

Dec. 31, 2016USD ($)

Dec. 31, 2016JOD (JD)

Dec. 31, 2016IDR (Rp)

Dec. 31, 2016PKR (₨)

Disclosure of detailed information about Long-term borrowings [Line Items]

Borrowings

₩ 2,584,280

₩ 2,110,727

Less : Discount on long-term borrowings

(21,999)

(26,838)

Less : Current portion of long-term borrowings

(128,543)

(310,977)

Add : Current portion of discount on long-term borrowings

886

979

Long-term borrowings

₩ 2,434,624

₩ 1,773,891

Local long-term borrowings 1 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Development Bank

Korea Development Bank

Purpose of borrowings

Others

Others

Borrowings interest rate

0.50

0.50

Borrowings, maturity

2018~2044

2018~2044

Borrowings

₩ 4,909

₩ 5,663

Local long-term borrowings 2 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Development Bank

Korea Development Bank

Purpose of borrowings

Facility

Facility

Borrowings interest rate

2.45~4.60

2.45~4.60

Borrowings, maturity

2023~2028

2023~2028

Borrowings

₩ 68,883

₩ 61,835

Local long-term borrowings 3 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Development Bank

Korea Development Bank

Purpose of borrowings

Facility

Facility

Borrowings interest rate

1yr KoFC bond rate+0.31

1yr KoFC bond rate+0.31

Borrowings, maturity

2,018

2,018

Borrowings

₩ 25,000

₩ 125,000

Local long-term borrowings 4 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Development Bank

Korea Development Bank

Purpose of borrowings

Operating funds

Operating funds

Borrowings interest rate

2.59~3.04

2.75

Borrowings, maturity

2018~2020

2,018

Borrowings

₩ 47,000

₩ 12,000

Local long-term borrowings 5 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Development Bank

Purpose of borrowings

Operating funds

Borrowings interest rate

1yr KoFC bond rate+0.95

Borrowings, maturity

2,020

Borrowings

₩ 14,000

Local long-term borrowings 6 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

KEB Hana Bank

KEB Hana Bank

Purpose of borrowings

Commercial Paper

Commercial Paper

Borrowings interest rate

3M CD+0.24~0.32

3M CD+0.14

Borrowings, maturity

2021~2022

2,017

Borrowings

₩ 400,000

₩ 100,000

Local long-term borrowings 7 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

KEB Hana Bank

KEB Hana Bank

Purpose of borrowings

Facility

Facility

Borrowings interest rate

4.60

4.60

Borrowings, maturity

2,028

2,028

Borrowings

₩ 15,038

₩ 16,851

Local long-term borrowings 8 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

KEB Hana Bank

KEB Hana Bank

Purpose of borrowings

Facility

Facility

Borrowings interest rate

3yr KTB rate-1.25

3yr KTB rate-1.25

Borrowings, maturity

2018~2028

2017~2028

Borrowings

₩ 8,947

₩ 9,655

Local long-term borrowings 9 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

IBK

IBK

Purpose of borrowings

PF Refinancing

PF Refinancing

Borrowings interest rate

CD+1.25

CD+1.25

Borrowings, maturity

2,030

2,030

Borrowings

₩ 22,500

₩ 22,500

Local long-term borrowings 10 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Export-Import Bank of Korea

Export-Import Bank of Korea

Purpose of borrowings

Project loans

Project loans

Borrowings interest rate

1.5

1.5

Borrowings, maturity

2,026

2,026

Borrowings

₩ 25,042

₩ 30,935

Local long-term borrowings 11 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Export-Import Bank of Korea

Purpose of borrowings

Operating funds

Borrowings interest rate

2.21

Borrowings, maturity

2,020

Borrowings

₩ 35,000

Local long-term borrowings 12 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Resources Corporation

Purpose of borrowings

Development of power resouces

Borrowings interest rate

3yr KTB rate -2.25

Borrowings, maturity

2022~2025

Borrowings

₩ 14,039

Local long-term borrowings 13 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Resources Corporation

Purpose of borrowings

Facility

Borrowings interest rate

3yr KTB rate -2.25

Borrowings, maturity

2017~2024

Borrowings

₩ 3,842

Local long-term borrowings 14 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Resources Corporation

Purpose of borrowings

Project loans

Borrowings interest rate

-

Borrowings, maturity

2022~2025

Borrowings

₩ 3,733

Local long-term borrowings 15 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea Resources Corporation

Purpose of borrowings

Others

Borrowings interest rate

KTB rate -2.25

Borrowings, maturity

2024~2025

Borrowings

₩ 12,131

Local long-term borrowings 16 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

[1]

Korea Energy Agency

Purpose of borrowings

[1]

Development of power resouces

Borrowings interest rate

[1]

3yr KTB rate-2.25

Borrowings, maturity

[1]

2023~2025

Borrowings

[1]

₩ 6,765

Local long-term borrowings 17 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

[1]

Korea Energy Agency

Purpose of borrowings

[1]

Facility loan

Borrowings interest rate

[1]

3yr KTB rate-2.25

Borrowings, maturity

[1]

2018~2024

Borrowings

[1]

₩ 3,121

Local long-term borrowings 18 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

[1]

Korea Energy Agency

Purpose of borrowings

[1]

Project loans

Borrowings interest rate

[1]

-

Borrowings, maturity

[1]

2022~2025

Borrowings

[1]

₩ 3,733

Local long-term borrowings 19 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

[1]

Korea Energy Agency

Purpose of borrowings

[1]

Others

Borrowings interest rate

[1]

KTB rate -2.25

Borrowings, maturity

[1]

2024~2028

Borrowings

[1]

₩ 18,455

Local long-term borrowings 20 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Shinhan Bank and others

Shinhan Bank and others

Purpose of borrowings

Collateral borrowing

Collateral borrowing

Borrowings interest rate

2.32

2.22

Borrowings, maturity

2,019

2,017

Borrowings

₩ 30,000

₩ 30,000

Local long-term borrowings 21 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Shinhan Bank and others

Shinhan Bank and others

Purpose of borrowings

Facility loan

Facility loan

Borrowings interest rate

CB rate+1.10

CB rate+1.10

Borrowings, maturity

2,028

2,028

Borrowings

₩ 22,557

₩ 25,276

Local long-term borrowings 22 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Shinhan Bank and others

Shinhan Bank and others

Purpose of borrowings

Operating funds

Operating funds

Borrowings interest rate

2.70

2.70~2.86

Borrowings, maturity

2,018

2017~2018

Borrowings

₩ 15,000

₩ 25,000

Local long-term borrowings 23 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Shinhan Bank and others

Shinhan Bank and others

Purpose of borrowings

Others

Others

Borrowings interest rate

4.10

4.10

Borrowings, maturity

2,035

2,035

Borrowings

₩ 105,000

₩ 55,000

Local long-term borrowings 24 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Shinhan Bank and others

Shinhan Bank and others

Purpose of borrowings

Others

Others

Borrowings interest rate

Standard overdraft rate +1.10

3yr KTB rate+1.10

Borrowings, maturity

2,035

2,035

Borrowings

₩ 105,000

₩ 55,000

Local long-term borrowings 25 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Kookmin Bank

Kookmin Bank

Purpose of borrowings

Facility loan

Facility loan

Borrowings interest rate

MOR+0.79

MOR+0.62~0.79

Borrowings, maturity

2,023

2017~2023

Borrowings

₩ 35,000

₩ 45,000

Local long-term borrowings 26 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Kookmin Bank

Purpose of borrowings

Facility loan

Borrowings interest rate

3.16

Borrowings, maturity

2,020

Borrowings

₩ 10,000

Local long-term borrowings 27 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Other Creditors

Other Creditors

Purpose of borrowings

Facility loan

Facility loan

Borrowings interest rate

1.75~4.60

1.75~4.60

Borrowings, maturity

2026~2029

2026~2029

Borrowings

₩ 148,423

₩ 146,472

Local long-term borrowings 28 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Other Creditors

Other Creditors

Purpose of borrowings

Facility loan

Facility loan

Borrowings interest rate

CB rate+1.10~1.20

CB rate+1.10~1.20

Borrowings, maturity

2022~2028

2022~2028

Borrowings

₩ 46,278

₩ 34,951

Local long-term borrowings 29 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Other Creditors

Other Creditors

Purpose of borrowings

PF Refinancing

PF Refinancing

Borrowings interest rate

4.1

4.1

Borrowings, maturity

2,030

2,030

Borrowings

₩ 62,500

₩ 62,500

Local long-term borrowings 30 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Other Creditors

Other Creditors

Purpose of borrowings

Others

Others

Borrowings interest rate

4.50~8.00

8

Borrowings, maturity

2022~2039

2,036

Borrowings

₩ 102,346

₩ 102,347

Local long-term borrowings 31 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Other Creditors

Purpose of borrowings

Others

Borrowings interest rate

-

Borrowings, maturity

2,028

Borrowings

₩ 7,250

Local long-term borrowings 32 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Borrowings

1,380,497

1,006,980

Foreign long-term borrowings [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Borrowings

₩ 1,203,783

₩ 1,103,747

Foreign long-term borrowings 1 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Korea National Oil Corporation

Purpose of borrowings

Project loans

Borrowings interest rate

-

Borrowings, maturity

2021~2023

Borrowings

₩ 10,567

$ 8,744

Foreign long-term borrowings 2 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

[1]

Korea Energy Agency

Purpose of borrowings

[1]

Project loans

Borrowings interest rate

[1]

-

Borrowings, maturity

[1]

2021~2023

Borrowings

₩ 9,368

[1]

$ 8,744

Foreign long-term borrowings 3 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Export-Import Bank of Korea and others

Purpose of borrowings

Direct loan and others

Borrowings interest rate

1M Libor+1.80~3.20

Borrowings, maturity

2,036

Borrowings

₩ 69,548

64,913

Foreign long-term borrowings 4 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Export-Import Bank of Korea and others

Export-Import Bank of Korea and others

Purpose of borrowings

Direct loan and others

Direct loan and others

Borrowings interest rate

3M Libor+2.75~3.70

3M Libor+2.75~3.70

Borrowings, maturity

2,027

2,027

Borrowings

₩ 254,514

₩ 305,332

JD 168,663

JD 178,892

Foreign long-term borrowings 5 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Export-Import Bank of Korea and others

Export-Import Bank of Korea and others

Purpose of borrowings

Commercial loan and others

Commercial loan and others

Borrowings interest rate

3M Libor+1.50~2.50

3M Libor+1.50~2.50

Borrowings, maturity

2030~2033

2030~2033

Borrowings

₩ 309,662

₩ 362,379

289,026

299,859

Foreign long-term borrowings 6 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Export-Import Bank of Korea and others

Export-Import Bank of Korea and others

Purpose of borrowings

PF Loan

PF Loan

Borrowings interest rate

6M Libor+1.70~2.50

6M Libor+2.50~2.70

Borrowings, maturity

2,032

2,032

Borrowings

₩ 132,054

₩ 144,594

123,253

119,647

Foreign long-term borrowings 7 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

SCNT and others

SCNT and others

Purpose of borrowings

Shareholder’s loan

Shareholder’s loan

Borrowings interest rate

6.50~8.00

6.50~8.00

Borrowings, maturity

2,023

2,023

Borrowings

₩ 44,697

₩ 49,086

41,718

40,618

Foreign long-term borrowings 8 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

SCNT and others

SCNT and others

Purpose of borrowings

Shareholder’s loan

Shareholder’s loan

Borrowings interest rate

8

8

Borrowings, maturity

2,031

2,031

Borrowings

₩ 7,750

₩ 12,166

JD 5,136

JD 7,128

Foreign long-term borrowings 9 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

PT PJB

PT PJB

Purpose of borrowings

Shareholder’s loan

Shareholder’s loan

Borrowings interest rate

12.75

12.75

Borrowings, maturity

2,019

2,019

Borrowings

₩ 864

₩ 1,500

Rp 10,932,568

Rp 16,705,505

Foreign long-term borrowings 10 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Samsung Life Insurance and others

Samsung Life Insurance and others

Purpose of borrowings

Syndicated loan

Syndicated loan

Borrowings interest rate

3.10

3.10

Borrowings, maturity

2,032

2,032

Borrowings

₩ 50,540

₩ 18,227

¥ 5,325,000

¥ 1,758,000

Foreign long-term borrowings 11 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Woori Bank and others

Woori Bank and others

Purpose of borrowings

Syndicated loan

Syndicated loan

Borrowings interest rate

JPY 6M Libor +2.00

JPY 6M Libor+2.10

Borrowings, maturity

2,032

2,032

Borrowings

₩ 32,602

₩ 12,151

¥ 3,435,000

¥ 1,172,000

Foreign long-term borrowings 12 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

SMBC and others

SMBC and others

Purpose of borrowings

Equity Bridge Loan

Equity Bridge Loan

Borrowings interest rate

1M Libor+0.90

1M Libor+0.90

Borrowings, maturity

2,019

2,019

Borrowings

₩ 76,054

₩ 45,897

70,986

37,978

Foreign long-term borrowings 13 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

IFC and others

IFC and others

Purpose of borrowings

Others

Others

Borrowings interest rate

6M Libor+5.00

6M Libor+5.00

Borrowings, maturity

2,031

2,031

Borrowings

₩ 161,195

₩ 134,972

₨ 16,652,350

₨ 11,706,160

Foreign long-term borrowings 14 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Federal Financing Bank

Purpose of borrowings

PF loan

Borrowings interest rate

2.39

Borrowings, maturity

2,031

Borrowings

₩ 51,819

48,366

Foreign long-term borrowings 15 [Member]

Disclosure of detailed information about Long-term borrowings [Line Items]

Name of Creditor

Other Creditors

Other Creditors

Purpose of borrowings

Others

Others

Borrowings interest rate

-

-

Borrowings, maturity

2,019

2,019

Borrowings

₩ 3,116

₩ 6,876

$ 2,907

$ 5,691

[1]

As of July 1, 2017, loan business for energy-related projects has been integrated into Korea Energy Agency in accordance with the Korean government’s restructuring of the public institutions.

Borrowings and Debt Securiti163

Borrowings and Debt Securities : Local debt securities and Foreign debt securities (Details) € in Thousands, ¥ in Thousands, kr in Thousands, SFr in Thousands, $ in Thousands, $ in Thousands, ₩ in Millions

12 Months Ended

Dec. 31, 2017KRW (₩)

Dec. 31, 2016KRW (₩)

Dec. 31, 2017JPY (¥)

Dec. 31, 2017USD ($)

Dec. 31, 2017CHF (SFr)

Dec. 31, 2017AUD ($)

Dec. 31, 2017EUR (€)

Dec. 31, 2017SEK (kr)

Dec. 31, 2016JPY (¥)

Dec. 31, 2016USD ($)

Dec. 31, 2016CHF (SFr)

Dec. 31, 2016AUD ($)

Debt Instrument [Line Items]

Bonds issued

₩ 51,232,007

₩ 50,838,270

Less : Discount on debt securities

(85,306)

(88,633)

Add : Premium on debt securities

82

156

Less : Current portion of debt securities

(7,961,182)

(7,825,310)

Add : Current portion of discount on debt securities

3,882

1,753

Total

43,189,483

42,926,236

Local Debt securities [Member]

Debt Instrument [Line Items]

Bonds issued

41,972,708

39,722,708

Less : Discount on debt securities

(37,816)

(34,667)

Less : Current portion of debt securities

(5,200,000)

(5,650,010)

Add : Current portion of discount on debt securities

923

728

Total

₩ 36,735,815

₩ 34,038,759

Electricity Bonds 1 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2009.12.03~ 2017.12.14

2009.12.03~ 2017.12.14

Debt Instrument, Maturity Date, Description

2018.01.07~ 2037.09.18

2018.01.07~ 2037.09.18

Interest rate (%)

1.62~5.45

1.62~5.45

Bonds issued

₩ 20,700,000

₩ 19,860,000

Electricity Bonds 2 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2013.06.25

2013.06.25

Debt Instrument, Maturity Date, Description

2018.06.25

2018.06.25

Interest rate (%)

3M CD+0.31

3M CD+0.31

Bonds issued

₩ 150,000

₩ 310,000

Corporate bonds [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

[1]

2009.05.04~ 2017.11.10

2009.05.04~ 2017.11.10

Debt Instrument, Maturity Date, Description

[1]

2018.01.18~2047.10.17

2018.01.18~2047.10.17

Interest rate (%)

[1]

1.36~5.84

1.36~5.84

Bonds issued

[1]

₩ 21,122,708

₩ 19,552,708

Foreign Debt securities [Member]

Debt Instrument [Line Items]

Bonds issued

9,259,299

11,115,562

Less : Discount on debt securities

(47,490)

(53,966)

Add : Premium on debt securities

82

156

Less : Current portion of debt securities

(2,761,182)

(2,175,300)

Add : Current portion of discount on debt securities

2,959

1,025

Total

₩ 6,453,668

₩ 8,887,477

FY-96 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

1996.04.01~1996.12.06

1996.04.01~1996.12.06

Debt Instrument, Maturity Date, Description

2026.12.06~2096.04.01

2026.12.06~2096.04.01

Interest rate (%)

6.00~8.37

6.00~8.37

Bonds issued

₩ 266,854

₩ 300,999

$ 249,070

$ 249,068

FY-97 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

1997.01.31~1997.08.04

1997.01.31~1997.08.04

Debt Instrument, Maturity Date, Description

2027.02.01~2027.08.01

2027.02.01~2027.08.01

Interest rate (%)

6.75~7.00

6.75~7.00

Bonds issued

₩ 337,188

₩ 380,335

314,717

314,717

FY-04 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2004.04.23

2004.04.23

Debt Instrument, Maturity Date, Description

2034.04.23

2034.04.23

Interest rate (%)

5.13

5.13

Bonds issued

₩ 307,406

₩ 346,743

286,920

286,920

FY-08 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2008.11.27

2008.11.27

Debt Instrument, Maturity Date, Description

2018.11.27

2018.11.27

Interest rate (%)

4.19

4.19

Bonds issued

₩ 189,822

₩ 207,362

¥ 20,000,000

¥ 20,000,000

FY-11 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2011.07.13

2011.07.13~2011.07.29

Debt Instrument, Maturity Date, Description

2021.07.13

2017.01.30~2021.07.13

Interest rate (%)

4.75

3.63~4.75

Bonds issued

₩ 535,700

₩ 966,800

500,000

800,000

FY-12 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2012.09.19

2012.05.10~2012.09.19

Debt Instrument, Maturity Date, Description

2022.09.19

2017.05.10~2022.09.19

Interest rate (%)

3

2.50~3.13

Bonds issued

₩ 803,550

₩ 2,114,875

750,000

1,750,000

FY-13_1 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2013.02.05~2013.11.27

2013.02.05~2013.11.27

Debt Instrument, Maturity Date, Description

2018.02.05~2018.11.27

2018.02.05~2018.11.27

Interest rate (%)

1.88~2.88

1.88~2.88

Bonds issued

₩ 2,035,660

₩ 2,296,150

1,900,000

1,900,000

FY-13_2 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2013.09.26~2013.10.23

2013.09.26~2013.10.23

Debt Instrument, Maturity Date, Description

2019.03.26~2019.04.23

2019.03.26~2019.04.23

Interest rate (%)

1.50~1.63

1.50~1.63

Bonds issued

₩ 437,888

₩ 472,532

SFr 400,000

SFr 400,000

FY-13_3 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2013.09.25

2013.09.25

Debt Instrument, Maturity Date, Description

2020.09.25

2020.09.25

Interest rate (%)

5.75

5.75

Bonds issued

₩ 271,427

₩ 283,416

$ 325,000

$ 325,000

FY-13_4 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2013.02.20~2013.07.25

2013.02.20~2013.07.25

Debt Instrument, Maturity Date, Description

2018.02.20~2018.07.25

2018.02.20~2018.07.25

Interest rate (%)

3M Libor+0.84~1.50

3M Libor+0.84~1.50

Bonds issued

₩ 535,700

₩ 604,250

500,000

500,000

FY-14_1 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2014.02.11~2014.12.02

2014.02.11~2014.12.02

Debt Instrument, Maturity Date, Description

2019.02.11~2029.07.30

2019.02.11~2029.07.30

Interest rate (%)

2.38~3.57

2.38~3.57

Bonds issued

₩ 1,607,100

₩ 1,812,750

1,500,000

1,500,000

FY-14_2 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2014.01.28~2014.07.31

Debt Instrument, Maturity Date, Description

2017.01.28~2017.07.31

Interest rate (%)

3M Libor+0.55~1.05

Bonds issued

₩ 604,250

500,000

FY-15 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2015.06.15

2015.06.15

Debt Instrument, Maturity Date, Description

2025.06.15

2025.06.15

Interest rate (%)

3.25

3.25

Bonds issued

₩ 321,420

₩ 362,550

300,000

300,000

FY-16 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2016.01.21

2016.01.21

Debt Instrument, Maturity Date, Description

2021.07.21

2021.07.21

Interest rate (%)

2.50

2.50

Bonds issued

₩ 321,420

₩ 362,550

300,000

$ 300,000

FY-17_1 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2017.04.12~2017.07.25

Debt Instrument, Maturity Date, Description

2020.04.12~2027.07.25

Interest rate (%)

2.38~3.13

Bonds issued

₩ 1,178,540

$ 1,100,000

FY-17_2 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2017.10.30

Debt Instrument, Maturity Date, Description

2037.10.30

Interest rate (%)

1.70

Bonds issued

₩ 51,170

€ 40,000

FY-17_3 [Member]

Debt Instrument [Line Items]

Debt Instrument, Issuance Date

2017.11.16

Debt Instrument, Maturity Date, Description

2037.11.16

Interest rate (%)

2.36

Bonds issued

₩ 58,454

kr 450,000

[1]

Corporate Bonds of HeeMang Sunlight Power Co., Ltd (￦2,697 million) can be redeemed every March 31 after five years from its issue date, March 31, 2016.

Finance Lease Liabilities (Deta

Finance Lease Liabilities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Finance Lease Liabilities [Line Items]
Minimum lease payments	₩ 556,276	₩ 731,788
Present value of minimum lease payments	418,260	541,179
Less than 1 year [Member]
Finance Lease Liabilities [Line Items]
Minimum lease payments	174,534	175,512
Present value of minimum lease payments	131,792	121,176
1~5 Years [Member]
Finance Lease Liabilities [Line Items]
Minimum lease payments	272,994	404,029
Present value of minimum lease payments	204,069	306,282
More than 5 years [Member]
Finance Lease Liabilities [Line Items]
Minimum lease payments	108,748	152,247
Present value of minimum lease payments	₩ 82,399	₩ 113,721

Finance Lease Liabilities _ Liq

Finance Lease Liabilities : Liquidity classification (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Finance Lease Liabilities [Abstract]
Current finance lease liabilities	₩ 131,792	₩ 121,176
Non-current finance lease liabilities	286,468	420,003
Total Finance Lease Liabilities	₩ 418,260	₩ 541,179

Finance Lease Liabilities _ Lea

Finance Lease Liabilities : Lease payments recognized as an expense from a lessee position (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Lease and sublease payments recognised as expense [Abstract]
Minimum lease payment	₩ 158,859	₩ 177,585
Contingent rent payment	₩ (21,024)	₩ (20,956)

Changes in finance lease liabil

Changes in finance lease liabilities (Details) ₩ in Millions	Dec. 31, 2017KRW (₩)
Disclosure - Changes in finance lease liabilities [Abstract]
Cash flow	₩ (122,919)
Acquisition of finance lease assets	₩ 0

Employment benefit obligations

Employment benefit obligations (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Employment Benefits [Abstract]
Net defined benefit obligations	₩ 1,476,201	₩ 1,678,470
Other long-term employee benefit obligations	6,868	7,788
Employee benefits liabilities, net	₩ 1,483,069	₩ 1,686,258

Principal assumptions on actuar

Principal assumptions on actuarial valuation (Details) - ₩ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure - Principal assumptions on actuarial valuation [Abstract]
Discount rate	2.75% ~ 2.90%	2.45% ~ 2.64%
Future salary and benefit levels	4.88%	5.23%
Weighted average duration	13.40	13.34

Details of expense relating to

Details of expense relating to defined benefit plans (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Details of expense relating to defined benefit plans [Abstract]
Current service cost	₩ 392,820	₩ 378,930	₩ 315,811
Interest cost	79,524	67,104	63,808
Expected return on plan assets	(31,307)	(23,612)	(22,557)
Loss from settlement	(1,055)	(706)	(641)
Defined benefit	₩ 439,982	₩ 421,716	₩ 356,421

Details of expense relating 171

Details of expense relating to defined benefit plans by nature (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Details of expense relating to defined benefit plans by nature [Abstract]
Defined benefit allocated to Cost of sales	₩ 332,249	₩ 312,391	₩ 262,760
Defined benefit allocated to Selling, general and administrative expense	59,111	61,362	51,932
Defined benefit allocated to others	48,622	47,963	41,729
Defined benefit	₩ 439,982	₩ 421,716	₩ 356,421

Defined benefit plan assets and

Defined benefit plan assets and liabilities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure - Defined benefit plan assets and liabilities [Abstract]
Present value of defined benefit obligation from funded plans	₩ 2,951,842	₩ 2,867,377
Fair value of plan assets	(1,475,641)	(1,188,907)
Net surplus (deficit) in plan	1,476,201	1,678,470
Present value of defined benefit obligation from unfunded plans	0	0
Net liabilities incurred from defined benefit plans	₩ 1,476,201	₩ 1,678,470

Net defined benefit liability (

Net defined benefit liability (asset) (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [Line Items]
Beginning balance		₩ 1,678,470
Changes in net defined benefit liability (asset) [Abstract]
Current service cost		392,820	₩ 378,930	₩ 315,811
Remeasurement component		(247,788)	126,699
Loss from settlement		1,055	706	641
Ending balance		1,476,201	1,678,470
Defined benefit obligation [Member]
Disclosure of defined benefit plans [Line Items]
Beginning balance		2,867,377	2,426,414
Changes in net defined benefit liability (asset) [Abstract]
Current service cost		392,820	378,930
Interest expense (income)	[1]	79,524	67,104
Remeasurement component		(258,223)	120,993
Loss from settlement		(1,055)	(707)
Actual payments		(128,707)	(125,233)
Others		106	(124)
Ending balance		2,951,842	2,867,377	2,426,414
Plan assets [Member]
Disclosure of defined benefit plans [Line Items]
Beginning balance		(1,188,907)	(930,632)
Changes in net defined benefit liability (asset) [Abstract]
Interest expense (income)		(31,307)	(23,612)
Remeasurement component		10,435	5,706
Contributions by the employers		(325,080)	(312,125)
Actual payments		59,218	71,756
Ending balance		₩ (1,475,641)	₩ (1,188,907)	₩ (930,632)
[1]	Corporate bond (AAA rated) yield at year-end is applied to measure the interest cost on employee benefit obligations.

Details of the fair value of pl

Details of the fair value of plan assets (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of fair value of plan assets [Abstract]
Equity instruments	₩ 79,204	₩ 86,054
Debt instruments	517,040	383,654
Bank deposit	293,477	305,670
Others	585,920	413,529
Plan assets	₩ 1,475,641	₩ 1,188,907

Gain (loss) on remeasurement, n

Gain (loss) on remeasurement, net defined benefit liability (asset) (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Gain (loss) on remeasurement, net defined benefit liability (asset) [Abstract]
Actuarial gain from changes in financial assumptions	₩ (300,058)	₩ (27,792)
Experience adjustments	41,835	148,785
Expected return	10,435	5,706
Total loss (gain) on remeasurement, net defined benefit liability (asset)	₩ (247,788)	₩ 126,699

Provisions (Details)

Provisions (Details) - KRW (₩) ₩ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Disclosure of other provisions [Line Items]
Net carrying value		₩ 15,427,139		₩ 14,443,930
Reconciliation of changes in other provisions [Abstract]
Beginning balance		15,427,139		14,443,930
Changes in other provisions [Abstract]
Increase in provision		5,292,348		3,325,450
Payment		(2,395,506)		(2,478,788)
Reversal of unused amount		(49,115)		(99,591)
Others		87,346		236,138
Ending balance		18,362,212		15,427,139
Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		2,137,498		1,999,988
Reconciliation of changes in other provisions [Abstract]
Beginning balance		1,999,988
Changes in other provisions [Abstract]
Ending balance		2,137,498		1,999,988
Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		16,224,714		13,427,151
Reconciliation of changes in other provisions [Abstract]
Beginning balance		13,427,151
Changes in other provisions [Abstract]
Ending balance		16,224,714		13,427,151
Provisions for employment benefits [Member]
Disclosure of other provisions [Line Items]
Net carrying value		810,607		718,365
Reconciliation of changes in other provisions [Abstract]
Beginning balance		810,607		718,365
Changes in other provisions [Abstract]
Increase in provision		984,896		1,047,342
Payment		(880,255)		(947,982)
Reversal of unused amount		(1,461)		(7,108)
Others				(10)
Ending balance		913,787		810,607
Provisions for employment benefits [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		810,607		810,607
Reconciliation of changes in other provisions [Abstract]
Beginning balance		810,607
Changes in other provisions [Abstract]
Ending balance		913,787		810,607
Litigation provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		198,237		167,965
Reconciliation of changes in other provisions [Abstract]
Beginning balance		198,237		167,965
Changes in other provisions [Abstract]
Increase in provision		34,629		124,931
Payment		(152,461)		(294,403)
Reversal of unused amount		(7,096)		(20,736)
Others		267		220,480
Ending balance		73,576		198,237
Litigation provisions [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		79,359		79,359
Reconciliation of changes in other provisions [Abstract]
Beginning balance		79,359
Changes in other provisions [Abstract]
Ending balance		48,621		79,359
Litigation provisions [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		118,878		118,878
Reconciliation of changes in other provisions [Abstract]
Beginning balance		118,878
Changes in other provisions [Abstract]
Ending balance		24,955		118,878
Provisions For Nuclear Plants Restoration [Member]
Disclosure of other provisions [Line Items]
Net carrying value		10,195,928		9,684,286
Reconciliation of changes in other provisions [Abstract]
Beginning balance		10,195,928		9,684,286
Changes in other provisions [Abstract]
Increase in provision		2,818,033		513,383
Payment		(6,733)		(1,741)
Ending balance		13,007,228		10,195,928
Provisions For Nuclear Plants Restoration [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		10,195,928		10,195,928
Reconciliation of changes in other provisions [Abstract]
Beginning balance		10,195,928
Changes in other provisions [Abstract]
Ending balance		13,007,228		10,195,928
Spent fuel recovery provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		1,374,225		1,375,185
Reconciliation of changes in other provisions [Abstract]
Beginning balance		1,374,225		1,375,185
Changes in other provisions [Abstract]
Increase in provision		307,682		469,982
Payment		(342,861)		(470,942)
Ending balance		1,339,046		1,374,225
Spent fuel recovery provisions [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		1,374,225		1,374,225
Reconciliation of changes in other provisions [Abstract]
Beginning balance		1,374,225
Changes in other provisions [Abstract]
Ending balance		1,339,046		1,374,225
Waste recovery provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		1,479,502		1,502,140
Reconciliation of changes in other provisions [Abstract]
Beginning balance		1,479,502		1,502,140
Changes in other provisions [Abstract]
Increase in provision		222,632		49,092
Payment		(63,763)		(71,998)
Others				268
Ending balance		1,638,371		1,479,502
Waste recovery provisions [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		2,566		2,566
Reconciliation of changes in other provisions [Abstract]
Beginning balance		2,566
Changes in other provisions [Abstract]
Ending balance		11,494		2,566
Waste recovery provisions [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		1,476,936		1,476,936
Reconciliation of changes in other provisions [Abstract]
Beginning balance		1,476,936
Changes in other provisions [Abstract]
Ending balance		1,626,877		1,476,936
PCBs recovery provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		191,744		182,400
Reconciliation of changes in other provisions [Abstract]
Beginning balance		191,744		182,400
Changes in other provisions [Abstract]
Increase in provision		5,309		30,675
Payment		(14,266)		(21,331)
Reversal of unused amount		(2,700)
Ending balance		180,087		191,744
PCBs recovery provisions [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		191,744		191,744
Reconciliation of changes in other provisions [Abstract]
Beginning balance		191,744
Changes in other provisions [Abstract]
Ending balance		180,087		191,744
Other recovery provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		507		862
Reconciliation of changes in other provisions [Abstract]
Beginning balance		507		862
Changes in other provisions [Abstract]
Increase in provision		5,939
Reversal of unused amount				(20)
Others		213		(335)
Ending balance		6,659		507
Other recovery provisions [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		507		507
Reconciliation of changes in other provisions [Abstract]
Beginning balance		507
Changes in other provisions [Abstract]
Ending balance		6,659		507
Power plant regional support program provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		152,851		129,655
Reconciliation of changes in other provisions [Abstract]
Beginning balance		152,851		129,655
Changes in other provisions [Abstract]
Increase in provision		94,039		50,252
Payment		(103,889)		(41,540)
Others		10,755		14,484
Ending balance		153,756		152,851
Power plant regional support program provisions [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		153,756		152,851
Reconciliation of changes in other provisions [Abstract]
Beginning balance		152,851
Changes in other provisions [Abstract]
Ending balance		153,756		152,851
Transmission regional support program provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		282,608		228,785
Reconciliation of changes in other provisions [Abstract]
Beginning balance		282,608		228,785
Changes in other provisions [Abstract]
Increase in provision		143,178		253,664
Payment		(182,421)		(199,841)
Ending balance		243,365		282,608
Transmission regional support program provisions [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		243,365		282,608
Reconciliation of changes in other provisions [Abstract]
Beginning balance		282,608
Changes in other provisions [Abstract]
Ending balance		243,365		282,608
Provisions for tax [Member]
Disclosure of other provisions [Line Items]
Net carrying value		242		136
Reconciliation of changes in other provisions [Abstract]
Beginning balance		242		136
Changes in other provisions [Abstract]
Increase in provision				125
Payment		(25)
Reversal of unused amount		(136)
Others		(20)		(19)
Ending balance		61		242
Provisions for tax [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		61		106
Reconciliation of changes in other provisions [Abstract]
Beginning balance		106
Changes in other provisions [Abstract]
Ending balance		61		106
Provisions for tax [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		0		136
Reconciliation of changes in other provisions [Abstract]
Beginning balance		136
Changes in other provisions [Abstract]
Ending balance		0		136
Provisions for financial guarantee [Member]
Disclosure of other provisions [Line Items]
Net carrying value		29,665		4,288
Reconciliation of changes in other provisions [Abstract]
Beginning balance		29,665		4,288
Changes in other provisions [Abstract]
Increase in provision		3,760		29,741
Reversal of unused amount		(9,945)		(4,298)
Others		(5)		(66)
Ending balance		23,475		29,665
Provisions for financial guarantee [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		23,475		458
Reconciliation of changes in other provisions [Abstract]
Beginning balance		458
Changes in other provisions [Abstract]
Ending balance		23,475		458
Provisions for financial guarantee [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		0		29,207
Reconciliation of changes in other provisions [Abstract]
Beginning balance		29,207
Changes in other provisions [Abstract]
Ending balance		0		29,207
Provisions for RPS [Member]
Disclosure of other provisions [Line Items]
Net carrying value		417,404		363,178
Reconciliation of changes in other provisions [Abstract]
Beginning balance		417,404		363,178
Changes in other provisions [Abstract]
Increase in provision		242,946		420,154
Payment		(388,726)		(309,975)
Reversal of unused amount				(55,953)
Ending balance		271,624		417,404
Provisions for RPS [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		417,404		417,404
Reconciliation of changes in other provisions [Abstract]
Beginning balance		417,404
Changes in other provisions [Abstract]
Ending balance		271,624		417,404
Provisions for greenhouse gas emissions obligations [Member]
Disclosure of other provisions [Line Items]
Net carrying value		249,644		78,829
Reconciliation of changes in other provisions [Abstract]
Beginning balance		249,644		78,829
Changes in other provisions [Abstract]
Increase in provision		422,666		298,618
Payment		(256,758)		(116,336)
Reversal of unused amount		(1,300)		(11,467)
Ending balance		414,252		249,644
Provisions for greenhouse gas emissions obligations [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		249,644		249,644
Reconciliation of changes in other provisions [Abstract]
Beginning balance		249,644
Changes in other provisions [Abstract]
Ending balance		414,252		249,644
Others [Member]
Disclosure of other provisions [Line Items]
Net carrying value		43,975	[1]	7,856
Reconciliation of changes in other provisions [Abstract]
Beginning balance		43,975	[1]	7,856
Changes in other provisions [Abstract]
Increase in provision		6,639	[1]	37,491
Payment		(3,348)	[1]	(2,699)
Reversal of unused amount		(26,477)	[1]	(9)
Others		76,136	[1]	1,336
Ending balance	[1]	96,925		43,975
Others [Member] | Current Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		4,385		4,385
Reconciliation of changes in other provisions [Abstract]
Beginning balance		4,385
Changes in other provisions [Abstract]
Ending balance		80,538		4,385
Others [Member] | Noncurrent Provisions [Member]
Disclosure of other provisions [Line Items]
Net carrying value		39,590		39,590
Reconciliation of changes in other provisions [Abstract]
Beginning balance		39,590
Changes in other provisions [Abstract]
Ending balance		₩ 16,387		₩ 39,590
[1]	As described in note 50.(1), the Company believes that the possibility of economic outflow is probable on the cost of construction suspension of Shin-Kori Unit 5 and 6 for three months. For this reason, the Company recognized ￦77,261 million of provision as addition to construction-in-progress.

Changes in government grants (D

Changes in government grants (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Government grants [Line Items]
Government grants	₩ (537,152)	₩ (527,095)
Changes in government grants [Abstract]
Beginning balance	(527,095)	(528,840)
Receipt	(55,533)	(32,878)
Acquisitions	129,451	33,516
Offset the items of depreciation expense and others	38,354	30,867
Disposals	2,441	4,552
Others	(124,770)	(34,312)
Ending balance	(537,152)	(527,095)
Cash [Member]
Changes in government grants [Abstract]
Receipt	(55,533)	(32,878)
Others	55,533	32,878
Land [Member]
Government grants [Line Items]
Government grants	(21,968)	(3,204)
Changes in government grants [Abstract]
Beginning balance	(3,204)	(3,147)
Disposals	5	14
Others	(18,769)	(71)
Ending balance	(21,968)	(3,204)
Buildings [Member]
Government grants [Line Items]
Government grants	(63,539)	(61,188)
Changes in government grants [Abstract]
Beginning balance	(61,188)	(63,932)
Offset the items of depreciation expense and others	5,996	5,299
Disposals	28	731
Others	(8,375)	(3,286)
Ending balance	(63,539)	(61,188)
Structures [Member]
Government grants [Line Items]
Government grants	(196,414)	(197,641)
Changes in government grants [Abstract]
Beginning balance	(197,641)	(193,119)
Offset the items of depreciation expense and others	10,011	9,491
Disposals	1,905	2,597
Others	(10,689)	(16,610)
Ending balance	(196,414)	(197,641)
Machinery [Member]
Government grants [Line Items]
Government grants	(183,188)	(111,064)
Changes in government grants [Abstract]
Beginning balance	(111,064)	(108,935)
Offset the items of depreciation expense and others	17,390	12,272
Disposals	489	1,210
Others	(90,003)	(15,611)
Ending balance	(183,188)	(111,064)
Vehicles [Member]
Government grants [Line Items]
Government grants	(6,322)	(107)
Changes in government grants [Abstract]
Beginning balance	(107)	(29)
Offset the items of depreciation expense and others	1,070	25
Disposals	14
Others	(7,299)	(103)
Ending balance	(6,322)	(107)
Equipment [Member]
Government grants [Line Items]
Government grants	(761)	(732)
Changes in government grants [Abstract]
Beginning balance	(732)	(1,026)
Offset the items of depreciation expense and others	454	452
Others	(483)	(158)
Ending balance	(761)	(732)
Tools [Member]
Government grants [Line Items]
Government grants	(1,027)	(430)
Changes in government grants [Abstract]
Beginning balance	(430)	(691)
Offset the items of depreciation expense and others	354	295
Others	(951)	(34)
Ending balance	(1,027)	(430)
Construction in progress [Member]
Government grants [Line Items]
Government grants	(49,084)	(135,807)
Changes in government grants [Abstract]
Beginning balance	(135,807)	(139,898)
Acquisitions	129,451	32,525
Others	(42,728)	(28,434)
Ending balance	(49,084)	(135,807)
Finance lease assets [Member]
Government grants [Line Items]
Government grants	(27)
Changes in government grants [Abstract]
Offset the items of depreciation expense and others	1
Others	(28)
Ending balance	(27)
Investment properties [Member]
Government grants [Line Items]
Government grants	(83)	(64)
Changes in government grants [Abstract]
Beginning balance	(64)	(13)
Offset the items of depreciation expense and others	2	1
Others	(21)	(52)
Ending balance	(83)	(64)
Software [Member]
Government grants [Line Items]
Government grants	(486)	(595)
Changes in government grants [Abstract]
Beginning balance	(595)	(699)
Offset the items of depreciation expense and others	255	249
Others	(146)	(145)
Ending balance	(486)	(595)
Development expenditures [Member]
Government grants [Line Items]
Government grants	(3,702)	(5,152)
Changes in government grants [Abstract]
Beginning balance	(5,152)	(6,835)
Offset the items of depreciation expense and others	2,811	2,771
Others	(1,361)	(1,088)
Ending balance	(3,702)	(5,152)
Intangible assets under development [Member]
Government grants [Line Items]
Government grants	(10,540)	(11,090)
Changes in government grants [Abstract]
Beginning balance	(11,090)	(10,483)
Acquisitions		991
Others	550	(1,598)
Ending balance	(10,540)	(11,090)
Usage rights of donated assets and other [Member]
Government grants [Line Items]
Government grants	(11)	(21)
Changes in government grants [Abstract]
Beginning balance	(21)	(32)
Offset the items of depreciation expense and others	10	11
Ending balance	₩ (11)	(21)
Others [Member]
Government grants [Line Items]
Government grants		(1)
Changes in government grants [Abstract]
Beginning balance		(1)
Offset the items of depreciation expense and others		₩ 1

Deferred Revenues (Details)

Deferred Revenues (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Deferred Revenue [Abstract]
Deferred Revenue, Beginning Balance	₩ 7,825,765	₩ 7,165,297
Increase during the current year / period	978,389	1,087,765
Recognized as revenue during the current year / period	(478,973)	(427,297)
Deferred Revenue, Ending Balance	₩ 8,325,181	₩ 7,825,765

Non-financial Liabilities (Deta

Non-financial Liabilities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Current Liabilities [Member]
Disclosure - Other liabilities [Line Items]
Advances received	₩ 3,772,713	₩ 4,498,739
Accrued income	41,593	26,084
Deferred revenue	476,631	445,018
Withholdings	164,370	263,263
Other nonfincial liabilities	1,129,001	1,135,106
Total	5,584,308	6,368,210
Other Noncurrent Liabilities [Member]
Disclosure - Other liabilities [Line Items]
Advances received	181,612	148,404
Accrued income	19,718	41,936
Deferred revenue	7,848,550	7,380,747
Withholdings	10,529	10,781
Other nonfincial liabilities	12,025	9,737
Total	₩ 8,072,434	₩ 7,591,605

Details of shares issued (Deta

Details of shares issued (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Common shares [Line Items]
Common shares		₩ 3,209,820	₩ 3,209,820
Owned by government [Member]
Common shares [Line Items]
Common shares	[1]	1,640,385	1,640,385
Owned by others [Member]
Common shares [Line Items]
Common shares		₩ 1,569,435	₩ 1,569,435
[1]	Korea Development Bank’s ownership of ￦1,056,176 million is included.

Details in number of outstandin

Details in number of outstanding capital stock (Details) - ₩ / shares	Dec. 31, 2017	Dec. 31, 2016
Disclosure of classes of share capital [Abstract]
Shares authorized	1,200,000,000	1,200,000,000
Shares issued	641,964,077	641,964,077
Par value per share	₩ 5,000	₩ 5,000

Details of share premium (Detai

Details of share premium (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Share premium [Abstract]
Share premium	₩ 843,758	₩ 843,758

Retained Earnings (Details)

Retained Earnings (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retained Earnings Note Disclosure [Abstract]
Legal reserves	[1]	₩ 1,604,910	₩ 1,604,910
Voluntary reserves [Abstract]
Reserve for investment on social overhead capital		5,277,449	5,277,449
Reserve for research and human development	[2]	330,000	330,000
Reserve for business expansion		29,016,395	26,029,826
Reserve for equalizing dividends		210,000	210,000
Voluntary reserves		34,833,844	31,847,275
Retained earnings before appropriations		16,931,804	19,721,686
Retained earnings		₩ 53,370,558	₩ 53,173,871	₩ 48,187,241
[1]	The KEPCO Act requires KEPCO to appropriate a legal reserve equal to at least 20 percent of net income for each accounting period until the reserve equals 50 percent of KEPCO’s common stock. The legal reserve is not available for cash dividends; however, this reserve may be credited to paid-in capital or offset against accumulated deficit by the resolution of the shareholders.
[2]	The reserve for research and human development is appropriated by KEPCO to use as qualified tax credits to reduce corporate tax liabilities. The reserve is available for cash dividends for a certain period as defined by the Restriction of Special Taxation Act of Korea.

Changes in retained earnings (D

Changes in retained earnings (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Changes in retained earnings [Abstract]
Beginning balance	₩ 53,173,871	₩ 48,187,241
Net profit for the period attributed to owner of the Company	1,298,720	7,048,581	₩ 13,289,127
Changes in equity method retained earnings [Abstract]
Beginning balance	(4,943)	(2,411)
Ending balance	5,122	(4,943)	(2,411)
Changes	10,065	(2,532)
Remeasurements of defined benefit liability, net of tax	158,991	(69,330)
Dividend paid	(1,271,089)	(1,990,089)	(320,982)
Ending balance	₩ 53,370,558	₩ 53,173,871	₩ 48,187,241

Dividends Paid (Details)

Dividends Paid (Details) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends [Abstract]
Number of shares issued	641,964,077	641,964,077	641,964,077
Treasury Stock, Common, Shares	0	0	0
Number of shares eligible for dividends	641,964,077	641,964,077	641,964,077
Dividends paid per share (In won)	₩ 1,980	₩ 3,100	₩ 500
Dividend paid	₩ 1,271,089	₩ 1,990,089	₩ 320,982

Changes in Reserve of remeasure

Changes in Reserve of remeasurements (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Changes in Reserve of remeasurements [Abstract]
Beginning balance	₩ (222,997)	₩ (202,878)
Changes	239,636	(119,316)
Income tax effect	(80,645)	49,986	₩ 42,913
Transfer to reserve for business expansion	20,493	49,211
Ending balance	₩ (43,513)	₩ (222,997)	₩ (202,878)

Statement of Appropriation o187

Statement of Appropriation of retained earnings (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Appropriation of Retained Earnings [Abstract]
Unappropriated retained earnings carried over from prior years	₩ 0	₩ 0
Net income	1,506,852	4,261,986
Remeasurements of defined benefit plans	72,723	(4,328)
Retained earnings before appropriations	1,579,575	4,257,658
Transfer from voluntary reserves	0	0
Subtotal (Ⅰ+Ⅱ)	1,579,575	4,257,658
Appropriations of retained earnings	(1,579,575)	(4,257,658)
Legal reserve	0	0
Dividends (government, individual) Amount of dividends per share (%) : Current year – W790 (16%) Prior year – W1,980 (40%)	(507,152)	(1,271,089)
Reserve for business expansion	(1,072,423)	(2,986,569)
Unappropriated retained earnings to be carried over to subsequent year	₩ 0	₩ 0

Hybrid bond (Details)

Hybrid bond (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Hybrid bond [Line Items]
Amount	₩ 398,910	₩ 498,660
Korea Western Power [Member] | 1st bond-type hybrid bond [Member]
Hybrid bond [Line Items]
Issue date		Oct. 18, 2012
Amount		₩ 100,000
Korea South-East Power [Member] | 1st bond-type hybrid bond [Member]
Hybrid bond [Line Items]
Issue date	Dec. 7, 2012	Dec. 7, 2012
Maturity date	Dec. 6, 2042	Dec. 6, 2042
Yield (%)	4.38%	4.38%
Amount	₩ 170,000	₩ 170,000
Korea South-East Power [Member] | 2nd bond-type hybrid bond [Member]
Hybrid bond [Line Items]
Issue date	Dec. 7, 2012	Dec. 7, 2012
Maturity date	Dec. 6, 2042	Dec. 6, 2042
Yield (%)	4.44%	4.44%
Amount	₩ 230,000	₩ 230,000
Expense of issuance [Member]
Hybrid bond [Line Items]
Amount	₩ (1,090)	₩ (1,340)

Other Components Of Equity (Det

Other Components Of Equity (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes In Other Components Of Equity [Line Items]
Beginning balance	₩ 14,496,244	₩ 14,393,648
Disposal of subsidiary		36,008
Issuance of share capital of subsidiary	(1,378)	1,750
Others	25
Changes in the unrealized fair value of available- for-sale financial assets, net of tax	(7,102)	61,275
Shares in other comprehensive loss of associates and joint ventures, net of tax	(154,991)	(54,918)
Foreign currency translation of foreign operations, net of tax	(95,103)	31,406
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	19,614	27,075
Ending balance	14,257,309	14,496,244
Other capital surplus [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	1,235,146	1,197,388
Disposal of subsidiary		36,008
Issuance of share capital of subsidiary	(1,378)	1,750
Others	25
Ending balance	1,233,793	1,235,146
Gains on disposal of Treasury stocks [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	387,524	387,524
Ending balance	387,524	387,524
Other Capital Surplus Other Than Gainson Disposal Of Treasury Stocks [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	847,622	809,864
Disposal of subsidiary		36,008
Issuance of share capital of subsidiary	(1,378)	1,750
Others	25
Ending balance	846,269	847,622
Accumulated other comprehensive loss [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	(33,875)	(98,713)
Changes in the unrealized fair value of available- for-sale financial assets, net of tax	(7,102)	61,275
Shares in other comprehensive loss of associates and joint ventures, net of tax	(154,991)	(54,918)
Foreign currency translation of foreign operations, net of tax	(95,103)	31,406
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	19,614	27,075
Ending balance	(271,457)	(33,875)
Available-for-sale financial asset valuation reserve [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	36,370	(24,905)
Changes in the unrealized fair value of available- for-sale financial assets, net of tax	(7,102)	61,275
Ending balance	29,268	36,370
Shares in other comprehensive Income (loss) of investments in associates and joint ventures [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	221,455	276,373
Shares in other comprehensive loss of associates and joint ventures, net of tax	(154,991)	(54,918)
Ending balance	66,464	221,455
Reserve for overseas operations translation credit [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	(223,056)	(254,462)
Foreign currency translation of foreign operations, net of tax	(95,103)	31,406
Ending balance	(318,159)	(223,056)
Reserve for gain (loss) on valuation of derivatives [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	(68,644)	(95,719)
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	19,614	27,075
Ending balance	(49,030)	(68,644)
Other equity [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	13,294,973	13,294,973
Ending balance	13,294,973	13,294,973
Statutory revaluation reserve [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	13,295,098	13,295,098
Ending balance	13,295,098	13,295,098
Changes in other equity [Member]
Changes In Other Components Of Equity [Line Items]
Beginning balance	(125)	(125)
Ending balance	₩ (125)	₩ (125)

Selling and Administrative E190

Selling and Administrative Expenses (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expenses by nature [Line Items]
Raw materials used	₩ 15,924,707	₩ 13,470,586	₩ 14,626,933
Salaries	4,214,974	4,160,642	3,617,908
Employee benefits expense	468,946	447,638	382,603
Welfare and benefit expense	723,144	669,934	546,052
Insurance expense	106,091	91,500	94,546
Depreciation	9,652,219	8,873,956	8,261,751
Amortization of intangible assets	113,672	79,715	72,266
Bad debt expense	126,714	38,719	290
Commission	1,143,435	1,029,058	915,874
Advertising expense	125,436	44,351	38,583
Training expense	21,389	19,661	16,174
Vehicle maintenance expense	17,466	17,406	18,852
Publishing expense	7,920	8,258	7,105
Business promotion expense	8,673	8,313	7,650
Rent expense	186,889	173,690	186,959
Telecommunication expense	98,872	101,373	95,858
Transportation expense	9,640	5,749	6,089
Taxes and dues	486,038	511,493	453,131
Expendable supplies expense	39,725	41,502	37,146
Water, light and heating expense	40,695	35,540	36,428
Repairs and maintenance expense	2,111,420	1,971,778	1,846,090
Ordinary development expense	721,437	705,504	611,220
Travel expense	85,673	79,726	67,298
Clothing expense	13,395	13,636	9,886
Survey and analysis expense	4,359	3,875	3,661
Membership fee	9,604	9,846	7,441
Power purchase	14,264,331	10,755,739	11,428,027
Disclosure - Other selling and administrative expenses [Abstract]
Accommodation development expenses	55,799	186,896	28,134
Miscellaneous wages	32,300	31,907	43,109
Litigation and filing expenses	11,881	12,328	10,670
Compensation for damages	12,297	60,341	9,032
Outsourcing expenses	2,647	3,530	2,865
Reward expenses	2,786	3,267	2,472
Overseas market development expenses	1,876	2,177	1,541
Others	35,123	31,086	34,037
Others	4,134,846	4,819,597	4,215,169
General and administrative expenses	2,762,855	2,639,232	2,153,261
Cost of sales	52,098,855	45,549,553	45,457,729
Total expenses, by nature	54,861,710	48,188,785	47,610,990
Selling and administrative expense [Member]
Expenses by nature [Line Items]
Salaries	735,383	734,930	655,432
Employee benefits expense	71,094	72,812	61,903
Welfare and benefit expense	179,406	162,243	119,866
Insurance expense	15,414	11,513	10,636
Depreciation	190,245	169,431	102,867
Amortization of intangible assets	44,990	35,171	40,465
Bad debt expense	126,714	38,719	290
Commission	673,740	605,879	562,171
Advertising expense	114,519	34,658	30,085
Training expense	7,027	6,314	4,988
Vehicle maintenance expense	9,998	10,390	10,529
Publishing expense	3,672	3,643	3,124
Business promotion expense	3,700	3,477	3,338
Rent expense	38,380	40,020	44,905
Telecommunication expense	24,916	25,448	22,678
Transportation expense	495	596	753
Taxes and dues	48,395	46,531	55,970
Expendable supplies expense	7,731	6,834	7,272
Water, light and heating expense	10,545	9,720	9,558
Repairs and maintenance expense	63,477	75,122	74,330
Ordinary development expense	211,417	188,063	178,472
Travel expense	16,658	16,115	14,388
Clothing expense	8,410	8,273	5,751
Survey and analysis expense	698	666	590
Membership fee	1,122	1,132	1,040
Disclosure - Other selling and administrative expenses [Abstract]
Accommodation development expenses	55,799	186,896	28,134
Miscellaneous wages	32,300	31,907	43,109
Litigation and filing expenses	11,881	12,328	10,670
Compensation for damages	12,297	60,341	9,032
Outsourcing expenses	2,647	3,530	2,865
Reward expenses	2,786	3,267	2,472
Overseas market development expenses	1,876	2,177	1,541
Others	35,123	31,086	34,037
Others	154,709	331,532	131,860
General and administrative expenses	2,762,855	2,639,232	2,153,261
Total expenses, by nature	₩ 2,762,855	₩ 2,639,232	₩ 2,153,261

Other Income and Expense (Detai

Other Income and Expense (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other non-operating income [Abstract]
Reversal of other provisions	₩ 35,265	₩ 22,034	₩ 6,355
Reversal of allowance for doubtful accounts	2,166	5,489	413
Gains on government grants	430	111	204
Gains on assets contributed	4,218	12,254	9,004
Gains on liabilities exempted	3,166	1,959	2,588
Compensation and reparations revenue	89,196	114,530	166,355
Revenue from research contracts	12,580	13,143	5,342
Income related to transfer of assets from customers	478,973	427,297	375,995
Rental income	192,136	211,580	196,406
Others of Other Income	50,988	31,787	45,552
Refund of claim for rectification	9,655	8,722	7,623
Adjustment of research project	3,884	4,148	4,090
Maintenance expenses on lease building	135	354	324
Training expenses	3,045	4,478	4,774
Deposit redemption	34	991	430
Reversal of expenses on litigation	360	893	219
Revenue on royalty fee	2,888	2,486	2,739
Reimbursement of insurance fee	1,498		11,797
Gains on guarantee contracts	456	2,796	4,523
Miscellaneous other non-operating income	29,033	6,919	9,033
Other non-operating income	869,118	840,184	808,214
Other non-operating expense [Abstract]
Compensation and indemnification expense	37		16,959
Accretion expenses of other provisions	7,535	4,556	4,575
Depreciation expenses on investment properties	1,176	678	669
Depreciation expenses on idle assets	6,644	6,639	6,698
Other bad debt expense	1,778	4,585	18,473
Donations	119,421	114,094	34,134
Others of Other Expense	43,464	58,072	27,340
Operating expenses related to the idle assets	136	459	779
Research grants	1,180	1,461	1,392
Supporting expenses on farming and fishing village	11,956	15,201	14,626
Operating expenses on fitness center	3,498	2,706	2,912
Expenses on adjustment of research and development grants	806		709
Taxes and dues	2,270	4,582	1,105
Expenses on R&D supporting	5,459	690	146
Moving expense			3,191
Miscellaneous other non-operating expense	18,159	32,973	2,480
Other non-operating expense	₩ 180,055	₩ 188,624	₩ 108,848

Other Gains (Losses) (Details)

Other Gains (Losses) (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other gains [Abstract]
Gains on disposal of property, plant and equipment	₩ 48,316	₩ 74,035	₩ 8,637,508
Gains on disposal of intangible assets	564		32
Reversal of impairment loss on intangible assets	54	3	275
Gains on foreign currency translation	20,485	15,311	13,784
Gains on foreign currency transaction	93,151	55,377	61,007
Gains on insurance proceeds	400		30
Miscellaneous Other Gains	269,562	187,792	162,128
Gains on disposal of inventories	6,024	9,494	10,758
Gains on valuation of inventories		2	7
Gains on proxy collection of TV license fee	39,711	38,991	38,529
Gains on compensation of impaired electric poles	1,526	3,650
Gains on compensation for infringement on contract	18,990	3,040	7,414
Gains on harbor facilities dues	3,025	2,957	5,943
Gains on technical fees	2,105	1,271	1,258
Reversal of occupation development training fees	1,697	1,756	1,878
Gains on disposal of waste	4,261	4,222	2,880
Gains on insurance	10,410	3,786	11,865
Gains on litigation			600
Gains on tax rebate	2,161	5,226	1,661
Gains on other commission	4,790	4,639	2,177
Gains on research tasks		10	1,446
Gains on settlement and others		2,188	2,803
Gains on sales of greenhouse gas emissions rights		46	52
Others of Miscellaneous Other Gains	174,862	106,514	72,857
Other losses [Abstract]
Losses on disposal of property, plant and equipment	(70,514)	(42,715)	(73,073)
Losses on disposal of intangible assets	(183)	(158)	(16)
Impairment loss on property, plant and equipment	(51,067)		(30,344)
Impairment loss on intangible assets	(20)	(3,945)	(22)
Losses on foreign currency translation	(25,495)	(23,835)	(15,097)
Losses on foreign currency transaction	(36,241)	(72,058)	(75,615)
Miscellaneous Other Losses	(92,385)	(119,309)	(69,824)
Losses on valuation of inventories	3,875	2,683	1,318
Losses on disposal of inventories	3,273	3,092	13,469
Losses due to disaster	5,374	1,522	263
Losses on rounding adjustment of electric charge surtax	1,253	1,260	1,251
Losses on adjustments of levies	1	1,184	13,928
Forfeit of taxes and dues	656	4,582	190
Losses on litigation		2,581	488
Others Of Miscellaneous Other Losses	77,953	102,405	38,917
Net other gains	₩ 156,627	₩ 70,498	₩ 8,610,773

Finance Income (Details)

Finance Income (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Income [Abstract]
Cash and cash equivalents	₩ 35,474	₩ 61,380	₩ 54,687
Available-for-sale financial assets	290		29
Held-to-maturity investments	82	97	99
Loans and receivables	30,014	25,106	28,586
Short-term financial instrument	29,412	45,763	46,921
Long-term financial instrument	8,144	7,195	10,492
Trade and other receivables	102,727	102,237	100,771
Total Interest Income	206,143	241,778	241,585
Dividend income	11,477	9,446	14,069
Gains on disposal of financial assets	1,130	1,482	4
Gains on valuation of Financial assets at fair value through profit or loss	12
Gains on valuation of derivatives	16,165	293,830	610,582
Gains on transaction of derivatives	29,257	45,549	151,851
Gains on foreign currency translation of Finance Income	1,115,832	161,905	127,372
Gains on foreign currency transaction	150,602	37,553	37,377
Other finance income			148
Total Finance Income	₩ 1,530,618	₩ 791,543	₩ 1,182,988

Finance Expenses (Details)

Finance Expenses (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Expense [Abstract]
Trade and other payables	₩ 57,160	₩ 68,375	₩ 84,527
Short-term borrowings	35,891	6,969	14,627
Long-term borrowings	87,011	91,584	103,503
Debt securities	1,698,232	1,922,900	2,177,855
Other financial liabilities	491,665	482,428	538,680
Interest Expense (Before Capitalizing borrowing costs)	2,369,959	2,572,256	2,919,192
Less: Capitalized borrowing costs	(580,407)	(819,388)	(903,508)
Interest expense	1,789,552	1,752,868	2,015,684
Losses on sale of financial assets	2,343	9	3,008
Impairment of available-for-sale financial assets	2,713	86,703	84,370
Losses on valuation of derivatives	890,832	5,762	17,051
Losses on transaction of derivatives	198,218	101,987	37,262
Losses on foreign currency translation	207,944	406,849	743,283
Losses on foreign currency transaction	35,175	57,889	113,723
Losses on repayment of financial liabilities	5	23,000	33
Other Finance Expenses	1,170	2,020	1,043
Total Finance Expense	₩ 3,127,952	₩ 2,437,087	₩ 3,015,457

Income tax expense (Details)

Income tax expense (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income tax expense [Abstract]
Current income tax expense	₩ 829,969	₩ 2,950,812	₩ 2,697,299
Payment of income tax	881,583	2,689,640	2,682,779
Adjustment due to changes in estimates related to prior years	4,484	231,113	(23,248)
Current income tax directly recognized in equity	(56,098)	30,059	37,768
Income tax directly adjusted to shareholders’ equity (except for accumulated other comprehensive income (loss))	5,223	(1,753)	(8,891)
Dividends of hybrid securities	5,248	5,253	5,253
Gain on disposal of investments in subsidiaries		(7,006)	(14,144)
Effect of change in effective tax rate	(25)
Income tax recognized as other comprehensive income (loss)	(61,321)	31,812	46,659
Gain (loss) on valuation of available-for-sale financial assets	(2,551)	(8,143)	(6,315)
Net change in the unrealized fair value of derivatives using cash flow hedge accounting, net of tax	(11,016)	(18,335)	7,253
Remeasurements of defined benefit obligations	(80,645)	49,986	42,913
Investments in associates	8,649	7,731	13,648
Others	24,242	573	(10,840)
Deferred income tax expense	1,342,855	414,329	2,542,114
Generation and realization of temporary differences	1,283,012	509,762	48,878
Changes of unrecognized tax losses, tax credit and temporary differences for prior periods	44,573	(86,845)	71,999
Changes in deferred tax on tax losses carryforwards			2,374,237
Tax credit carryforwards	15,270	(8,588)	47,000
Income tax expense	₩ 2,172,824	₩ 3,365,141	₩ 5,239,413

Income tax expense _ Reconcilia

Income tax expense : Reconciliation between actual income tax expense and amount computed by applying the statutory tax rate of 24.2% to income before income taxes (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Income tax expense calculated by multiplying net income before tax with the tax rate [Abstract]
Profit before income tax	₩ 3,614,218	₩ 10,513,468	₩ 18,655,786
Income tax expense computed at applicable tax rate of 24.2%	874,641	2,544,259	4,514,700
Adjustments	1,293,699	589,769	747,961
Effect of applying gradual tax rate	(5,082)	(5,082)	(4,147)
Effect of non-taxable income	(32,032)	(29,554)	(8,047)
Effect of non-deductible expenses	15,032	22,258	17,734
Effects of tax credits and deduction	(161,069)	(194,731)	(103,435)
Recognition (reversal) of unrecognized deferred tax asset, net	44,573	(86,845)	71,999
Effect of change in deferred tax due to change in tax rate (from 24.2% to 27.5%)	1,055,154
Deferred income tax related to investments in subsidiaries and associates	394,145	862,956	784,793
Others, net	(17,022)	20,767	(10,936)
Adjustment in respect of prior years due to change in estimate	4,484	231,113	(23,248)
Income tax expense	₩ 2,172,824	₩ 3,365,141	₩ 5,239,413
Effective tax rate	60.00%	32.00%	28.00%

Deferred tax expenses by origin

Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	₩ (8,153,389)	₩ (7,739,060)
Amounts recognized in profit or loss	(1,286,757)	(444,388)
Amount recognized in other comprehensive income (loss)	(61,321)	31,812	₩ 46,659
Amounts recognized directly in equity	5,223	(1,753)	(8,891)
Ending balance	(9,496,244)	(8,153,389)	(7,739,060)
Deferred income tax on temporary differences [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(8,189,092)	(7,766,172)
Amounts recognized in profit or loss	(1,271,485)	(452,979)
Amount recognized in other comprehensive income (loss)	(61,321)	31,812
Amounts recognized directly in equity	5,223	(1,753)
Ending balance	(9,516,675)	(8,189,092)	(7,766,172)
Employee benefits [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	493,331	407,342
Amounts recognized in profit or loss	86,008	36,003
Amount recognized in other comprehensive income (loss)	(80,645)	49,986
Ending balance	498,694	493,331	407,342
Cash flow hedges [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(53,583)	(29,013)
Amounts recognized in profit or loss	130,044	(6,235)
Amount recognized in other comprehensive income (loss)	(11,016)	(18,335)
Ending balance	65,445	(53,583)	(29,013)
Investments in associates or subsidiaries [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(7,166,345)	(6,449,998)
Amounts recognized in profit or loss	(1,510,295)	(717,072)
Amount recognized in other comprehensive income (loss)	8,649	7,731
Amounts recognized directly in equity	(25)	(7,006)
Ending balance	(8,668,016)	(7,166,345)	(6,449,998)
Property, Plant and Equipment [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(5,527,318)	(5,495,786)
Amounts recognized in profit or loss	(1,333,122)	(31,532)
Ending balance	(6,860,440)	(5,527,318)	(5,495,786)
Finance lease [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(345,431)	(272,430)
Amounts recognized in profit or loss	(81,518)	(73,001)
Ending balance	(426,949)	(345,431)	(272,430)
Intangible Assets [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	8,987	9,420
Amounts recognized in profit or loss	(1,339)	(433)
Ending balance	7,648	8,987	9,420
Financial assets at fair value through profit or loss [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(62)	(4)
Amounts recognized in profit or loss	952	(58)
Ending balance	890	(62)	(4)
Available-for-sale financial assets [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(68,347)	(49,199)
Amounts recognized in profit or loss	62,055	(11,005)
Amount recognized in other comprehensive income (loss)	(2,551)	(8,143)
Ending balance	(8,843)	(68,347)	(49,199)
Deferred revenue [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	213,859	215,361
Amounts recognized in profit or loss	16,852	(1,502)
Ending balance	230,711	213,859	215,361
Provisions, others [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	3,583,371	3,372,423
Amounts recognized in profit or loss	1,239,462	210,948
Ending balance	4,822,833	3,583,371	3,372,423
Doubtful receivables [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	2,696	1,405
Amounts recognized in profit or loss	(2,637)	1,291
Ending balance	59	2,696	1,405
Other finance liabilities [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	30,249	26,298
Amounts recognized in profit or loss	(2,742)	(1,302)
Amounts recognized directly in equity	5,248	5,253
Ending balance	32,755	30,249	26,298
Gains or losses on foreign exchange translation [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	138,938	128,714
Amounts recognized in profit or loss	(140,292)	10,224
Ending balance	(1,354)	138,938	128,714
Allowance for Doubtful Accounts [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	17,252	18,976
Amounts recognized in profit or loss	25,679	(1,724)
Ending balance	42,931	17,252	18,976
Accrued income [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(5,367)	(11,231)
Amounts recognized in profit or loss	3,542	5,864
Ending balance	(1,825)	(5,367)	(11,231)
Special deduction for property, plant and equipment [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(194,309)	(194,347)
Amounts recognized in profit or loss	(6,618)	38
Ending balance	(200,927)	(194,309)	(194,347)
Reserve for research and human development [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	(12,883)	(20,688)
Amounts recognized in profit or loss	9,842	7,805
Ending balance	(3,041)	(12,883)	(20,688)
Others [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	695,870	576,585
Amounts recognized in profit or loss	232,642	118,712
Amount recognized in other comprehensive income (loss)	24,242	573
Ending balance	952,754	695,870	576,585
Deferred income tax on unused tax losses and tax credit [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	35,703	27,112
Amounts recognized in profit or loss	(15,272)	8,591
Ending balance	20,431	35,703	27,112
Tax losses [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	0	(3)
Amounts recognized in profit or loss	0	3
Amount recognized in other comprehensive income (loss)	0	0
Amounts recognized directly in equity	0	0
Ending balance	0	0	(3)
Tax credit [Member]
Deferred tax expenses by origination and reversal of deferred assets and liabilities and temporary differences [Line Items]
Beginning balance	35,703	27,115
Amounts recognized in profit or loss	(15,272)	8,588
Ending balance	₩ 20,431	₩ 35,703	₩ 27,115

Deferred tax assets and liabili

Deferred tax assets and liabilities presented on a gross basis prior to any offsetting (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Deferred tax assets and liabilities presented on a gross basis prior to any offsetting [Abstract]
Deferred income tax assets	₩ 919,153	₩ 795,131
Deferred income tax liabilities	(10,415,397)	(8,948,520)
Net Deferred income tax assets(liabilities)	₩ (9,496,244)	₩ (8,153,389)	₩ (7,739,060)

Details of deductible temporary

Details of deductible temporary differences, tax losses and unused tax credits not recognized in the deferred income tax assets (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [Abstract]
Deductible temporary differences	₩ 444,426	₩ 426,718

Assets Held-for-Sale (Details)

Assets Held-for-Sale (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Assets Held-for-Sale [Abstract]
Land	[1]	₩ 2,765	₩ 2,907
Building	[1]	19,369	20,366
Investments in associates	[2],[3],[4]	5,837	42,569
Assets Held-for-Sale		₩ 27,971	₩ 65,842
[1]	The board of directors of KEPCO Engineering & Construction Company, Inc., a subsidiary of the Company, determined to dispose the office building in Yongin as part of the government’s plan to relocate state-run companies for balanced national development and moved the head office to Kimchun, Kyungsangbukdo, in 2015. As the Company believes the book value of Yongin office will be recovered by a disposal transaction rather than continuous operation, it reclassified buildings, land and structures as assets held-for-sale.
[2]	KEPCO Engineering & Construction Company, Inc., a subsidiary of the Company, exercised a put option to sell the shares of DS POWER Co., Ltd. on December 11, 2017 and the shares are expected to be sold on February 28, 2018. Thus, the Company reclassified the relevant book value to assets held-for-sale.
[3]	Korea Hydro & Nuclear Power Co., Ltd., a subsidiary of the Company, initiated efforts to sell its shares in Yeongwol Energy Station Co., Ltd. during the year ended December 31, 2016. KHNP won the first trial of the lawsuit against the counterparty on November 2, 2017. However, the planned sale period has been extended since the appeal is ongoing as of December 31, 2017. The Company expects the sale to occur in 2018.
[4]	Korea Western Power Co., Ltd., a subsidiary of the Company, planned to dispose certain portion of its investment in Dongducheon Dream Power Co., Ltd. and had classified the relevant book value as non-current assets held-for-sale. However, due to uncertainty of sale, it reclassified the relevant book value to investments in associates during the year ended December 31, 2017.

Expenses by nature (Details)

Expenses by nature (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expenses by nature [Line Items]
Raw materials used	₩ 15,924,707	₩ 13,470,586	₩ 14,626,933
Salaries	4,214,974	4,160,642	3,617,908
Employee benefits expense	468,946	447,638	382,603
Welfare and benefit expense	723,144	669,934	546,052
Insurance expense	106,091	91,500	94,546
Depreciation	9,652,219	8,873,956	8,261,751
Amortization of intangible assets	113,672	79,715	72,266
Bad debt expense	126,714	38,719	290
Commission	1,143,435	1,029,058	915,874
Advertising expense	125,436	44,351	38,583
Training expense	21,389	19,661	16,174
Vehicle maintenance expense	17,466	17,406	18,852
Publishing expense	7,920	8,258	7,105
Business promotion expense	8,673	8,313	7,650
Rental expense	186,889	173,690	186,959
Telecommunication expense	98,872	101,373	95,858
Transportation expense	9,640	5,749	6,089
Taxes and dues	486,038	511,493	453,131
Expendable supplies expense	39,725	41,502	37,146
Water, light and heating expense	40,695	35,540	36,428
Repairs and maintenance expense	2,111,420	1,971,778	1,846,090
Ordinary development expense	721,437	705,504	611,220
Travel expense	85,673	79,726	67,298
Clothing expense	13,395	13,636	9,886
Survey and analysis expense	4,359	3,875	3,661
Membership fee	9,604	9,846	7,441
Power purchase	14,264,331	10,755,739	11,428,027
Disclosure - Other selling and administrative expenses [Abstract]
Accommodation development expenses	55,799	186,896	28,134
Miscellaneous wages	32,300	31,907	43,109
Litigation and filing expenses	11,881	12,328	10,670
Compensation for damages	12,297	60,341	9,032
Outsourcing expenses	2,647	3,530	2,865
Reward expenses	2,786	3,267	2,472
Overseas market development expenses	1,876	2,177	1,541
Others	35,123	31,086	34,037
Others	4,134,846	4,819,597	4,215,169
General and administrative expenses	2,762,855	2,639,232	2,153,261
Cost of sales	52,098,855	45,549,553	45,457,729
Total expenses, by nature	54,861,710	48,188,785	47,610,990
Selling and administrative expense [Member]
Expenses by nature [Line Items]
Salaries	735,383	734,930	655,432
Employee benefits expense	71,094	72,812	61,903
Welfare and benefit expense	179,406	162,243	119,866
Insurance expense	15,414	11,513	10,636
Depreciation	190,245	169,431	102,867
Amortization of intangible assets	44,990	35,171	40,465
Bad debt expense	126,714	38,719	290
Commission	673,740	605,879	562,171
Advertising expense	114,519	34,658	30,085
Training expense	7,027	6,314	4,988
Vehicle maintenance expense	9,998	10,390	10,529
Publishing expense	3,672	3,643	3,124
Business promotion expense	3,700	3,477	3,338
Rental expense	38,380	40,020	44,905
Telecommunication expense	24,916	25,448	22,678
Transportation expense	495	596	753
Taxes and dues	48,395	46,531	55,970
Expendable supplies expense	7,731	6,834	7,272
Water, light and heating expense	10,545	9,720	9,558
Repairs and maintenance expense	63,477	75,122	74,330
Ordinary development expense	211,417	188,063	178,472
Travel expense	16,658	16,115	14,388
Clothing expense	8,410	8,273	5,751
Survey and analysis expense	698	666	590
Membership fee	1,122	1,132	1,040
Disclosure - Other selling and administrative expenses [Abstract]
Accommodation development expenses	55,799	186,896	28,134
Miscellaneous wages	32,300	31,907	43,109
Litigation and filing expenses	11,881	12,328	10,670
Compensation for damages	12,297	60,341	9,032
Outsourcing expenses	2,647	3,530	2,865
Reward expenses	2,786	3,267	2,472
Overseas market development expenses	1,876	2,177	1,541
Others	35,123	31,086	34,037
Others	154,709	331,532	131,860
General and administrative expenses	2,762,855	2,639,232	2,153,261
Total expenses, by nature	2,762,855	2,639,232	2,153,261
Cost of sales [Member]
Expenses by nature [Line Items]
Raw materials used	15,924,707	13,470,586	14,626,933
Salaries	3,479,591	3,425,712	2,962,476
Employee benefits expense	397,852	374,826	320,700
Welfare and benefit expense	543,738	507,691	426,186
Insurance expense	90,677	79,987	83,910
Depreciation	9,461,974	8,704,525	8,158,884
Amortization of intangible assets	68,682	44,544	31,801
Commission	469,695	423,179	353,703
Advertising expense	10,917	9,693	8,498
Training expense	14,362	13,347	11,186
Vehicle maintenance expense	7,468	7,016	8,323
Publishing expense	4,248	4,615	3,981
Business promotion expense	4,973	4,836	4,312
Rental expense	148,509	133,670	142,054
Telecommunication expense	73,956	75,925	73,180
Transportation expense	9,145	5,153	5,336
Taxes and dues	437,643	464,962	397,161
Expendable supplies expense	31,994	34,668	29,874
Water, light and heating expense	30,150	25,820	26,870
Repairs and maintenance expense	2,047,943	1,896,656	1,771,760
Ordinary development expense	510,020	517,441	432,748
Travel expense	69,015	63,611	52,910
Clothing expense	4,985	5,363	4,135
Survey and analysis expense	3,661	3,209	3,071
Membership fee	8,482	8,714	6,401
Power purchase	14,264,331	10,755,739	11,428,027
Disclosure - Other selling and administrative expenses [Abstract]
Others	3,980,137	4,488,065	4,083,309
Cost of sales	52,098,855	45,549,553	45,457,729
Total expenses, by nature	₩ 52,098,855	₩ 45,549,553	₩ 45,457,729

Basic earnings per share (Detai

Basic earnings per share (Details) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic earnings per share [Abstract]
Net profit for the period attributed to owner of the Company	₩ 1,298,720	₩ 7,048,581	₩ 13,289,127
Profit used in the calculation of total basic earnings per share	₩ 1,298,720	₩ 7,048,581	₩ 13,289,127
Weighted average number of common shares	641,964,077	641,964,077	641,964,077
Basic earnings per share	₩ 2,023	₩ 10,980	₩ 20,701

Diluted earnings per share (Det

Diluted earnings per share (Details) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Diluted earnings per share [Abstract]
Profit used in the calculation of total diluted earnings per share	₩ 1,298,720	₩ 7,048,581	₩ 13,289,127
Weighted average number of common shares	641,964,077	641,964,077	641,964,077
Diluted weighted average number of shares	641,964,077	641,964,077	641,964,077
Diluted earnings per share	₩ 2,023	₩ 10,980	₩ 20,701

Capital risk management (Detail

Capital risk management (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Capital risk management [Abstract]
Total borrowings and debt securities	₩ 54,747,392	₩ 53,639,205
Cash and cash equivalents	2,369,739	3,051,353	₩ 3,783,065	₩ 1,796,300
Net borrowings and debt securities	52,377,653	50,587,852
Total shareholder’s equity	₩ 72,964,641	₩ 73,050,545	₩ 67,942,475	₩ 54,825,010
Debt to equity ratio	71.78%	69.25%

Maximum exposure to credit risk

Maximum exposure to credit risk (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		₩ 2,369,739	₩ 3,051,353
Not Designated as Hedging Instrument [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		22,020	367,477
Designated as Hedging Instrument [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		10,606	413,897
Available-for-sale financial assets [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		699,833	1,014,732
Held-to-maturity investments [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		3,144	3,244
Loans and receivables [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		905,641	834,207
Long-term/short-term financial instruments [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		2,244,514	2,695,926
Financial assets at fair value through profit or loss [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		111,512
Trade and other receivables [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk		9,683,769	9,692,391
Financial guarantee contracts [Member]
Disclosure of detailed information about financial instruments [Line Items]
Maximum exposure to credit risk	[1]	₩ 1,154,862	₩ 1,396,152
[1]	Maximum exposure associated with the financial guarantee contracts is the maximum amounts of the obligation.

Sensitivity analysis for actuar

Sensitivity analysis for actuarial assumptions (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Actuarial assumption of expected rates of salary increases [Member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
1% Increase	₩ 354,852	₩ 344,874
1% Decrease	(305,494)	(304,685)
Actuarial assumption of discount rates [Member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
1% Increase	(313,597)	(305,031)
1% Decrease	₩ 377,148	₩ 371,689

Principal assumptions on provis

Principal assumptions on provisions valuation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
PCBs [Member]
Disclosure of Principal assumptions on provisions valuation [Line Items]
Inflation rate	1.23%	1.29%
Discount rate	2.55%	2.77%
Nuclear plants [Member]
Disclosure of Principal assumptions on provisions valuation [Line Items]
Inflation rate	1.21%	1.40%
Discount rate	2.94%	3.55%
Spent fuel [Member]
Disclosure of Principal assumptions on provisions valuation [Line Items]
Inflation rate	2.93%	2.93%
Discount rate	4.49%	4.49%

Sensitivity analysis for provis

Sensitivity analysis for provisions assumptions (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
PCBs [Member] | Discount rate [Member]
Disclosure of Sensitivity analysis for provisions assumptions [Line Items]
0.1% Increase	₩ (811)	₩ (817)
0.1% Decrease	816	822
PCBs [Member] | Inflation rate [Member]
Disclosure of Sensitivity analysis for provisions assumptions [Line Items]
0.1% Increase	826	834
0.1% Decrease	(822)	(830)
Nuclear plants [Member] | Discount rate [Member]
Disclosure of Sensitivity analysis for provisions assumptions [Line Items]
0.1% Increase	(262,949)	(209,277)
0.1% Decrease	270,370	215,139
Nuclear plants [Member] | Inflation rate [Member]
Disclosure of Sensitivity analysis for provisions assumptions [Line Items]
0.1% Increase	287,926	240,115
0.1% Decrease	(280,249)	(233,553)
Spent fuel [Member] | Discount rate [Member]
Disclosure of Sensitivity analysis for provisions assumptions [Line Items]
0.1% Increase	(51,015)	(52,353)
0.1% Decrease	52,997	54,387
Spent fuel [Member] | Inflation rate [Member]
Disclosure of Sensitivity analysis for provisions assumptions [Line Items]
0.1% Increase	53,763	55,173
0.1% Decrease	₩ (51,823)	₩ (53,182)

Foreign currency risk (Details)

Foreign currency risk (Details) ₸ in Thousands, ₱ in Thousands, € in Thousands, ₨ in Thousands, ₨ in Thousands, ৳ in Thousands, ر.س in Thousands, د.إ in Thousands, ¥ in Thousands, ¥ in Thousands, £ in Thousands, kr in Thousands, kr in Thousands, SFr in Thousands, Rp in Thousands, R in Thousands, P in Thousands, JD in Thousands, Ar in Thousands, $ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands

Dec. 31, 2017JPY (¥)

Dec. 31, 2017USD ($)

Dec. 31, 2017JOD (JD)

Dec. 31, 2017SAR (ر.س)

Dec. 31, 2017CHF (SFr)

Dec. 31, 2017AUD ($)

Dec. 31, 2017EUR (€)

Dec. 31, 2017SEK (kr)

Dec. 31, 2017INR (₨)

Dec. 31, 2017PHP (₱)

Dec. 31, 2017ZAR (R)

Dec. 31, 2017AED (د.إ)

Dec. 31, 2017BDT (৳)

Dec. 31, 2017BWP (P)

Dec. 31, 2017CAD ($)

Dec. 31, 2017CNY (¥)

Dec. 31, 2017GBP (£)

Dec. 31, 2017IDR (Rp)

Dec. 31, 2017KZT (₸)

Dec. 31, 2017MGA (Ar)

Dec. 31, 2017PKR (₨)

Dec. 31, 2017UYU ($)

Dec. 31, 2017NOK (kr)

Dec. 31, 2016JPY (¥)

Dec. 31, 2016USD ($)

Dec. 31, 2016JOD (JD)

Dec. 31, 2016SAR (ر.س)

Dec. 31, 2016CHF (SFr)

Dec. 31, 2016AUD ($)

Dec. 31, 2016EUR (€)

Dec. 31, 2016INR (₨)

Dec. 31, 2016PHP (₱)

Dec. 31, 2016ZAR (R)

Dec. 31, 2016AED (د.إ)

Dec. 31, 2016BDT (৳)

Dec. 31, 2016BWP (P)

Dec. 31, 2016GBP (£)

Dec. 31, 2016IDR (Rp)

Dec. 31, 2016KZT (₸)

Dec. 31, 2016MGA (Ar)

Dec. 31, 2016PKR (₨)

Dec. 31, 2016UYU ($)

Disclosure of Foreign currency risk [Abstract]

Assets

¥ 799,501

$ 1,653,858

JD 1,624

ر.س 1,191

$ 145

€ 5,708

₨ 1,228,259

₱ 189,261

R 361

د.إ 5,693

৳ 60,208

P 797

$ 82

¥ 13,007

£ 3

Rp 167,775

₸ 359

Ar 2,762,572

₨ 251,190

$ 12,955

¥ 520,746

$ 1,319,524

JD 1,746

ر.س 1,149

$ 187

€ 17,585

₨ 1,059,092

₱ 415,818

R 386

د.إ 7,479

৳ 49,110

P 4,296

£ 3

Rp 52,568

₸ 12,157

Ar 3,408,579

₨ 274,090

$ 1,307

Liabilities

¥ 21,624,128

$ 8,321,335

JD 5

ر.س 44

SFr 400,004

$ 652,259

€ 68,003

kr 449,002

₨ 227,078

₱ 125,431

R 4

د.إ 2,049

৳ 1,001

$ 171

¥ 26,140

£ 2,327

Ar 319,581

₨ 4,676

$ 10,586

kr 482

¥ 20,442,504

$ 9,445,567

JD 5

SFr 400,308

$ 632,613

€ 14,111

₨ 161,631

₱ 136,700

R 75

د.إ 1,534

৳ 833

P 3,222

£ 110

Ar 150,430

₨ 5,051

$ 586

Sensitivity analysis for Foreig

Sensitivity analysis for Foreign currency exchange rates (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Increase (decrease) of income before income tax [Member]
Disclosure of Sensitivity analysis for Foreign currency exchange rates [Line Items]
10% Increase	₩ (844,122)	₩ (1,101,372)
10% Decrease	844,122	1,101,372
Increase (decrease) of shareholder’s equity [Member]
Disclosure of Sensitivity analysis for Foreign currency exchange rates [Line Items]
10% Increase	(844,122)	(1,101,372)
10% Decrease	₩ 844,122	₩ 1,101,372

Interest rate risk (Details)

Interest rate risk (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial instruments by type of interest rate [Line Items]
Short-term borrowings	₩ 1,165,985	₩ 1,115,521
Long-term borrowings	2,434,624	1,773,891
Debt securities	51,146,783	50,749,793
Total	54,747,392	53,639,205
Floating interest rate [Member]
Disclosure of financial instruments by type of interest rate [Line Items]
Short-term borrowings	290,873	289,322
Long-term borrowings	1,743,252	1,459,969
Debt securities	685,700	1,518,500
Total	2,719,825	3,267,791
Fixed interest rate [Member]
Disclosure of financial instruments by type of interest rate [Line Items]
Short-term borrowings	875,112	826,199
Long-term borrowings	691,372	313,922
Debt securities	50,461,083	49,231,293
Total	₩ 52,027,567	₩ 50,371,414

Sensitivity analysis for Intere

Sensitivity analysis for Interest rates (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Increase (decrease) of income before income tax [Member]
Disclosure of Sensitivity analysis for Interest rates [Line Items]
1% Increase	₩ (27,198)	₩ (32,678)
1% Decrease	27,198	32,678
Increase (decrease) of shareholder’s equity [Member]
Disclosure of Sensitivity analysis for Interest rates [Line Items]
1% Increase	(27,198)	(32,678)
1% Decrease	₩ 27,198	₩ 32,678

Sensitivity analysis for electr

Sensitivity analysis for electricity rates (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Increase (decrease) of income before income tax [Member]
Disclosure of Sensitivity analysis for electricity rates [Line Items]
1% Increase	₩ 546,499	₩ 543,045
1% Decrease	(546,499)	(543,045)
Increase (decrease) of shareholder’s equity [Member]
Disclosure of Sensitivity analysis for electricity rates [Line Items]
1% Increase	546,499	543,045
1% Decrease	₩ (546,499)	₩ (543,045)

Maturity analysis for non-deriv

Maturity analysis for non-derivative financial liabilities (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Borrowings and debt securities		₩ 62,723,018	₩ 64,214,727
Finance lease liabilities		556,276	731,788
Trade and other payables		8,804,741	8,602,407
Financial guarantee contracts	[1]	1,154,862	1,396,152
Non-derivative financial liabilities, undiscounted cash flows		73,238,897	74,945,074
Less than 1 year [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Borrowings and debt securities		10,748,437	10,613,185
Finance lease liabilities		174,534	175,512
Trade and other payables		5,867,729	5,464,234
Financial guarantee contracts	[1]	7,081	249,200
Non-derivative financial liabilities, undiscounted cash flows		16,797,781	16,502,131
1~2 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Borrowings and debt securities		7,948,320	9,786,209
Finance lease liabilities		87,709	174,534
Trade and other payables		301,165	307,222
Financial guarantee contracts	[1]	18,054	40,617
Non-derivative financial liabilities, undiscounted cash flows		8,355,248	10,308,582
2~5 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Borrowings and debt securities		21,331,394	19,353,498
Finance lease liabilities		185,284	229,495
Trade and other payables		698,289	660,426
Financial guarantee contracts	[1]	1,049,667	865,842
Non-derivative financial liabilities, undiscounted cash flows		23,264,634	21,109,261
More than 5 years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Borrowings and debt securities		22,694,867	24,461,835
Finance lease liabilities		108,749	152,247
Trade and other payables		1,937,558	2,170,525
Financial guarantee contracts	[1]	80,060	240,493
Non-derivative financial liabilities, undiscounted cash flows		₩ 24,821,234	₩ 27,025,100
[1]	This represents the total guarantee amounts associated with the financial guarantee contracts. Financial guarantee liabilities which are recognized as of December 31, 2016 and 2017 are ￦29,665 million and ￦23,475 million, respectively.

Maturity analysis for non-de215

Maturity analysis for non-derivative financial assets (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of maturity analysis for financial assets held for managing liquidity risk [Line Items]
Cash and cash equivalents		₩ 2,369,739	₩ 3,051,353	₩ 3,783,065	₩ 1,796,300
Available-for-sale financial assets		699,833	1,014,732
Held-to-maturity investments		3,144	3,244	₩ 3,623
Loans and receivables		946,430	876,954
Long-term/short-term financial instruments		2,244,514	2,695,926
Financial assets at fair value through profit or loss		111,512
Trade and other receivables		9,692,080	9,700,732
Financial assets held for managing liquidity risk		16,067,252	17,342,941
Less than 1 year [Member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [Line Items]
Cash and cash equivalents		2,369,739	3,051,353
Held-to-maturity investments		5	114
Loans and receivables		244,309	198,133
Long-term/short-term financial instruments		1,702,084	2,281,460
Trade and other receivables		7,930,715	7,790,953
Financial assets held for managing liquidity risk		12,246,852	13,322,013
1~5 Years [Member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [Line Items]
Held-to-maturity investments		3,139	3,126
Loans and receivables		261,672	233,564
Long-term/short-term financial instruments		201,821	200,001
Trade and other receivables		920,539	915,679
Financial assets held for managing liquidity risk		1,387,171	1,352,370
More than 5 years [Member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [Line Items]
Available-for-sale financial assets		214,156
Held-to-maturity investments			4
Loans and receivables		429,628	439,666
Long-term/short-term financial instruments		340,304	214,122
Financial assets at fair value through profit or loss		111,512
Trade and other receivables		788,795	919,901
Financial assets held for managing liquidity risk		1,884,395	1,573,693
Other [Member]
Disclosure of maturity analysis for financial assets held for managing liquidity risk [Line Items]
Available-for-sale financial assets	[1]	485,677	1,014,732
Loans and receivables	[1]	10,821	5,591
Long-term/short-term financial instruments	[1]	305	343
Trade and other receivables	[1]	52,031	74,199
Financial assets held for managing liquidity risk	[1]	₩ 548,834	₩ 1,094,865
[1]	The maturities cannot be presently determined.

Maturity analysis for derivativ

Maturity analysis for derivative financial liabilities (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	₩ (376,587)	₩ (148,273)
Net settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(774)
Gross settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(92,947)	(29,924)
Gross settlement [Member] | Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(282,866)	(118,349)
Less than 1 year [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(69,817)	(5,726)
Less than 1 year [Member] | Net settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(774)
Less than 1 year [Member] | Gross settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(51,496)	(3,081)
Less than 1 year [Member] | Gross settlement [Member] | Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(17,547)	(2,645)
1~2 Years [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(48,864)	(26,689)
1~2 Years [Member] | Gross settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(19,887)	(24,044)
1~2 Years [Member] | Gross settlement [Member] | Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(28,977)	(2,645)
2~5 Years [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(208,802)	(56,484)
2~5 Years [Member] | Gross settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(16,597)
2~5 Years [Member] | Gross settlement [Member] | Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(192,205)	(56,484)
More than 5 years [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(49,104)	(59,374)
More than 5 years [Member] | Gross settlement [Member] | Not Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	(4,967)	(2,799)
More than 5 years [Member] | Gross settlement [Member] | Designated as Hedging Instrument [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities, undiscounted cash flows	₩ (44,137)	₩ (56,575)

Fair value measurement of instr

Fair value measurement of instruments (Details) - KRW (₩) ₩ in Millions		Dec. 31, 2017	Dec. 31, 2016
Financial assets, category [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		₩ 3,088,485	₩ 4,492,032
Fair value		3,088,485	4,492,032
Financial assets, category [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		12,962,293	13,581,195
Fair value		12,962,293	13,581,195
Available-for-sale financial assets [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value	[1]	699,833	1,014,732
Fair value	[1]	699,833	1,014,732
Derivative Financial Instruments, Assets [Member] | Not Designated as Hedging Instrument [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		22,020	367,477
Fair value		22,020	367,477
Derivative Financial Instruments, Assets [Member] | Designated as Hedging Instrument [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		10,606	413,897
Fair value		10,606	413,897
Long-term financial instruments [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		542,430	414,466
Fair value		542,430	414,466
Short-term financial instruments [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		1,702,084	2,281,460
Fair value		1,702,084	2,281,460
Financial assets at fair value through profit or loss [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		111,512
Fair value		111,512
Held-to-maturity investments [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		3,144	3,244
Fair value		3,144	3,244
Loans and receivables [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		905,641	834,207
Fair value		905,641	834,207
Trade receivables [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		9,683,769	9,692,391
Fair value		9,683,769	9,692,391
Cash and Cash Equivalents [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		2,369,739	3,051,353
Fair value		2,369,739	3,051,353
Liabilities [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		428,059	138,686
Fair value		428,059	138,686
Liabilities [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		63,970,393	62,782,791
Fair value		66,261,128	66,498,346
Derivative Financial Instruments, Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		150,929	21,529
Fair value		150,929	21,529
Derivative Financial Instruments, Liabilities [Member] | Designated as Hedging Instrument [Member] | Assets recognized at fair value [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		277,130	117,157
Fair value		277,130	117,157
Secured borrowings [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		1,055,554	744,565
Fair value		1,055,554	744,565
Unsecured bond [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		51,146,783	50,749,793
Fair value		53,436,659	54,455,659
Finance lease liabilities [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		418,260	541,179
Fair value		418,260	541,179
Unsecured borrowings [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		2,476,196	2,089,885
Fair value		2,477,055	2,099,574
Trade and other payables [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value	[2]	8,804,741	8,602,407
Fair value	[2]	8,804,741	8,602,407
Bank overdraft [Member] | Assets carried at amortized cost [Member]
Disclosure of fair value measurement of instruments [Line Items]
Book value		68,859	54,962
Fair value		₩ 68,859	₩ 54,962
[1]	Book values of equity securities held by the Company that were measured at cost as of December 31, 2016 and 2017 are ￦138,557 million and ￦37,926 million, respectively, as a quoted market price does not exist in an active market and its fair value cannot be measured reliably.
[2]	Excludes finance lease liabilities.

Significant unobservable inputs

Significant unobservable inputs used in fair value measurement of liabilities (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivatives [Member]
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [Line Items]
Interest rate, significant unobservable inputs, liabilities	0.03% ~ 4.16%	0.02% ~ 4.16%
Borrowings and debt securities [Member]
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [Line Items]
Interest rate, significant unobservable inputs, liabilities	0.08% ~ 4.38%	0.02% ~ 4.38%
Finance lease [Member]
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [Line Items]
Interest rate, significant unobservable inputs, liabilities	9.00% ~ 10.83%	9.00% ~ 10.83%

Fair value measurement of asset

Fair value measurement of assets (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of fair value measurement of assets [Line Items]
Available-for-sale financial assets	₩ 699,833	₩ 1,014,732
Financial assets at fair value through profit or loss	111,512
At fair value [Member]
Disclosure of fair value measurement of assets [Line Items]
Available-for-sale financial assets	661,907	974,647
Derivative assets	32,626	781,374
Financial assets at fair value through profit or loss	111,512
Total	806,045	1,756,021
At fair value [Member] | Level 1 [Member]
Disclosure of fair value measurement of assets [Line Items]
Available-for-sale financial assets	274,453	268,171
Total	274,453	268,171
At fair value [Member] | Level 2 [Member]
Disclosure of fair value measurement of assets [Line Items]
Available-for-sale financial assets	214,156	437,015
Derivative assets	18,466	770,851
Financial assets at fair value through profit or loss	111,512
Total	344,134	1,207,866
At fair value [Member] | Level 3 [Member]
Disclosure of fair value measurement of assets [Line Items]
Available-for-sale financial assets	173,298	269,461
Derivative assets	14,160	10,523
Total	₩ 187,458	₩ 279,984

Fair value measurement of liabi

Fair value measurement of liabilities (Details) - At fair value [Member] - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of fair value measurement of liabilities [Line Items]
Derivative liabilities	₩ 428,059	₩ 138,686
Level 2 [Member]
Disclosure of fair value measurement of liabilities [Line Items]
Derivative liabilities	₩ 428,059	₩ 138,686

Reconciliation of changes in fa

Reconciliation of changes in fair value measurement, assets (Details) - At fair value [Member] - Level 3 [Member] - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of changes in fair value measurement, assets [Line Items]
Beginning balance	₩ 269,461	₩ 180,390
Changes in fair value measurement, assets [Abstract]
Acquisition	0	0
Reclassified category	(92,128)	98,472
Valuation	(6,201)	(9,401)
Disposal	0	0
Foreign currency translation	2,166	0
Ending balance	₩ 173,298	₩ 269,461

Service Concession Arrangeme222

Service Concession Arrangements (Details) ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)
Disclosure of detailed information about service concession arrangements [Line Items]
Gas Complex ∙ Thermal Power Plant at Ilijan, Philippines (BOT)	₩ 494,279
Hydroelectric Power Generation at Semangka, Indonesia (BOT)	665,795
Less than 1 year [Member]
Disclosure of detailed information about service concession arrangements [Line Items]
Gas Complex ∙ Thermal Power Plant at Ilijan, Philippines (BOT)	111,912
Hydroelectric Power Generation at Semangka, Indonesia (BOT)	20,332
1~2 Years [Member]
Disclosure of detailed information about service concession arrangements [Line Items]
Gas Complex ∙ Thermal Power Plant at Ilijan, Philippines (BOT)	111,912
Hydroelectric Power Generation at Semangka, Indonesia (BOT)	26,888
2~3 Years [Member]
Disclosure of detailed information about service concession arrangements [Line Items]
Gas Complex ∙ Thermal Power Plant at Ilijan, Philippines (BOT)	111,912
Hydroelectric Power Generation at Semangka, Indonesia (BOT)	26,888
Over 3 years [Member]
Disclosure of detailed information about service concession arrangements [Line Items]
Gas Complex ∙ Thermal Power Plant at Ilijan, Philippines (BOT)	158,543
Hydroelectric Power Generation at Semangka, Indonesia (BOT)	₩ 591,687

Transactions between related pa

Transactions between related parties (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Daegu Green Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales			₩ 1,055
Dongducheon Dream Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	₩ 17,041	₩ 15,221	14,811
Electricity purchase	813,440	946,463	1,003,346
Outstanding balances for related party transactions [Abstract]
Trade receivables	2,230	1,073
Trade payables	77,817	93,493
Non-trade receivables and others	655
Korea Gas Corporation [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	88,011	89,030	90,480
Purchase of power generation fuel	3,245,519	3,633,198	4,598,763
Outstanding balances for related party transactions [Abstract]
Trade receivables	9,833	8,739
Trade payables	524,881	399,563
Non-trade receivables and others	339	78
Non-trade payables and others	569	9,090
Daegu Photovoltaic Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	349
REC purchase	3,646	3,243	3,978
Outstanding balances for related party transactions [Abstract]
Trade payables	71	56
Jeongam Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	30	6	8
Outstanding balances for related party transactions [Abstract]
Non-trade payables and others	4	4
Korea Power Engineering Service Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	1,317	1,455	1,743
Service purchase	1,292	723	3,241
KS Solar Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	5	20	21
REC purchase	900	4,080	6,211
Outstanding balances for related party transactions [Abstract]
Trade receivables		2
Trade payables		53
Heang Bok Do Si Photovoltaic Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	2	2	1
Rental fee and others	570	410	479
Korea Electric Power Industrial Development Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	14,044	10,723	12,361
Electricity metering service fee	289,293	250,057	273,057
Outstanding balances for related party transactions [Abstract]
Trade receivables	333	362
Non-trade receivables and others	42	47
Non-trade payables and others	18,006	18,628
Goseong Green Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	24,069	9,195	9,306
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	19
Non-trade payables and others	7,140	3,900
Gangneung Eco Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	2,391	5,223	9,761
Outstanding balances for related party transactions [Abstract]
Trade receivables	1	1
Non-trade receivables and others	4,747	2,137
Shin Pyeongtaek Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	9,025	3,579	11,344
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	210	215
Non-trade payables and others	52
Naepo Green Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	185	104	66
Outstanding balances for related party transactions [Abstract]
Trade receivables	17	14
Noeul Green Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	32	177	45
Service purchase	15,862
Outstanding balances for related party transactions [Abstract]
Trade receivables	3	18
Non-trade payables and others	2,041
Samcheok Eco Materials Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	237	64
Electricity purchase	14
Outstanding balances for related party transactions [Abstract]
Trade receivables	20	21
YTN Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	1,987	1,785	1,753
Advertisement fee	731	554	440
Outstanding balances for related party transactions [Abstract]
Trade receivables	98	165
Non-trade payables and others	209	132
Busan Green Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	120	133	1
Service purchase	12,189
Outstanding balances for related party transactions [Abstract]
Trade receivables	7	9
Non-trade receivables and others	1,691
Gunsan Bio Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales		6
Korea Electric Vehicle Charge Service [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	700	89	2
Service purchase	1,093
Outstanding balances for related party transactions [Abstract]
Trade receivables	23	12
Trade payables	45
Ulleungdo Natural Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	1,013	691	229
Electricity purchase	119	60
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others		111
Tamra Offshore Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	55	12
Electricity purchase	2,105
Daegu clean Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	421
Cheongna Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	7,980	6,831	21,081
Service purchase	59	73
Outstanding balances for related party transactions [Abstract]
Trade receivables	182	165
Non-trade payables and others	1	82
Gangwon Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	994	1,273	1,046
Electricity purchase	25,968	22,780	21,946
Outstanding balances for related party transactions [Abstract]
Trade receivables	6	8
Trade payables	3,033	2,031
Hyundai Green Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Design service	14,280	14,835	15,401
Electricity purchase	458,378	469,547	486,443
Outstanding balances for related party transactions [Abstract]
Trade receivables	946	569
Trade payables	32,589	31,507
Korea Power Exchange [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	8,446	7,141	4,272
Trading Fees	207,855	91,433	79,283
Outstanding balances for related party transactions [Abstract]
Trade receivables	463	1,066
Non-trade receivables and others	128	53
Non-trade payables and others	1,142	1,235
Hyundai Energy [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	15,627	24,719	25,402
Electricity purchase	87,607	1,313	1,684
Outstanding balances for related party transactions [Abstract]
Trade receivables	49	72
Trade payables	223	86
Non-trade receivables and others	6,598	68,798
Non-trade payables and others	13,796
Taebaek Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	813	796	872
REC purchase	6,534	5,741	6,626
Outstanding balances for related party transactions [Abstract]
Trade receivables	116
Trade payables	533	386
Non-trade receivables and others		112
Non-trade payables and others	121	304
Pyeongchang Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Design service	1,176	497	72
Service purchase	4,033	1,594
Outstanding balances for related party transactions [Abstract]
Trade receivables	3	4
Non-trade payables and others	163	255
Daeryun Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	1,796	1,516	1,731
Electricity purchase	146,189	244,023	274,379
Outstanding balances for related party transactions [Abstract]
Trade receivables	162	140
Trade payables	15,706	21,646
Changjuk Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	788	863	754
Electricity purchase	6,981	5,786	6,472
Outstanding balances for related party transactions [Abstract]
Trade receivables	101	100
Trade payables	515	358
Non-trade payables and others	546	334
KNH Solar Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	17	17	17
Electricity purchase	3,947	4,006	4,598
Outstanding balances for related party transactions [Abstract]
Trade receivables	1	1
Non-trade payables and others	193	204
S-Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	12,852	5,994	7,278
Electricity purchase	457,329	437,206	614,658
Outstanding balances for related party transactions [Abstract]
Trade receivables	117	142
Trade payables	25,061	51,844
Non-trade receivables and others	5,183	393
Busan Solar [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales		8	16
Electricity purchase		1,079	4,055
Green Biomass Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales		2	51
Woodchip purchase	1,345	2,232	3,782
Outstanding balances for related party transactions [Abstract]
Non-trade payables and others	85	113
SPC Power Corporation [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	5,562	8,346	1,433
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	76
Gemeng International Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	13,365	16,476	37,163
PT. Cirebon Electric Power [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	550
Dolphin Property Limited [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income		35
PT. Bayan Resources TBK [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	717	160	164
Nepal Water & Energy Development Company Private Limited [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	900	375
Service purchase	72
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	227	889
Pioneer Gas Power Limited [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	62	164	274
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others		82
Xe-Pian Xe-Namnoy Power [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	661	773	584
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	53	58
PT. Mutiara Jawa [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	47
Ecollite Co., Ltd. [Member]
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	210	210
Daegu Green Power [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	1,131	768
Electricity purchase	252,024	263,797	318,221
Outstanding balances for related party transactions [Abstract]
Trade receivables	98	52
Trade payables	25,257	27,400
Non-trade receivables and others	10	1
KEPCO SPC Power Corporation [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	45,005	10,344	29,572
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others		2,349
Daejung Offshore Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	1	1	1
KAPES, Inc. (formerly, KEPCO-ALSTOM Power Electronics Systems, Inc.) [Member]
Disclosure of transactions between related parties [Line Items]
Commission	1,420	1,176	1,315
Service purchase	164,165	140,555	47,130
Outstanding balances for related party transactions [Abstract]
Trade payables	55
Non-trade receivables and others		235
Non-trade payables and others		11,992
Dangjin Eco Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Technical fee	670	1,787	334
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	1,211	833
Non-trade payables and others	41
Honam Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	552	169	65
Electricity purchase	5,962	6,776	5,944
Outstanding balances for related party transactions [Abstract]
Trade payables	381	424
Non-trade payables and others	3,013	3,082
Seokmun Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	1,765	1,627	2,395
REC purchase	21,674
Outstanding balances for related party transactions [Abstract]
Trade receivables	93	114
Non-trade receivables and others	276	160
Non-trade payables and others	3,052
Incheon New Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Construction revenue	539	524	388
Outstanding balances for related party transactions [Abstract]
Trade receivables	128	128
KW Nuclear Components Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	644	3,327	1,948
Outstanding balances for related party transactions [Abstract]
Trade receivables	4
Chun-cheon Energy Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	4,855	3,079	2,201
REC purchase	194,136
Outstanding balances for related party transactions [Abstract]
Trade receivables	129
Trade payables	29,676
Non-trade receivables and others	252	255
Yeonggwangbaeksu Wind Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	1,654	1,591	927
Electricity purchase	11,124	11,208	4,974
Outstanding balances for related party transactions [Abstract]
Trade receivables	7	6
Trade payables	619	761
Non-trade receivables and others	144	145
Non-trade payables and others	1,300	1,362
KEPCO-Uhde Inc. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	34	6
Outstanding balances for related party transactions [Abstract]
Non-trade payables and others	4	4
GS Donghae Electric Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	11,204	12,994	5,614
Electricity purchase	351,367	903
Outstanding balances for related party transactions [Abstract]
Trade receivables	450	775
Trade payables	73,570
Non-trade receivables and others	1,892	1,497
Non-trade payables and others		993
Busan Shinho Solar Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	87	210	24
REC purchase	7,984	6,770	7,565
Outstanding balances for related party transactions [Abstract]
Trade receivables	2	3
Trade payables	159	129
Non-trade payables and others	811	670
Global Trade Of Power System Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service purchase	414	882	192
Datang Chifeng Renewable Power [Member]
Disclosure of transactions between related parties [Line Items]
Interest income	500	8,216	9,702
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	82	210
Rabigh Electricity Company [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	19,179	699	565
Rabigh Operation & Maintenance Company [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	2,784	2,395	1,780
Outstanding balances for related party transactions [Abstract]
Trade receivables		2,275
Non-trade receivables and others	869
Datang Chaoyang Renewable Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	839
Shuweihat Asia Power Investment B.V. [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income	1,707	2,957
Shuweihat Asia Operation & Maintenance Company [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	1,319	1,179	1,006
ASM-BG Investicii AD [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	1,062	322
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	37	64
Expressway Solar-light Power [Member]
Disclosure of transactions between related parties [Line Items]
Electricity purchase	2,941	2,942	3,451
Jamaica Public Service Company Limited [Member]
Disclosure of transactions between related parties [Line Items]
Service sales		1,905	3,077
Service purchase	154	127	106
Outstanding balances for related party transactions [Abstract]
Trade receivables		615
KV Holdings, Inc. [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income		302
Datang KEPCO Chaoyang Renewable Power Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Dividend income		440
Amman Asia Electric Power Company [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	14,205	21,915	48,968
Service purchase			125
Outstanding balances for related party transactions [Abstract]
Trade receivables	2,675	2,509
Kelar S.A [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	570	1,702	6,229
Nghi Son 2 Power Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	2,693
Barakah One Company [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	7,059	25,244
Service purchase	2,631
Nawah Energy Company [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	34,421
Outstanding balances for related party transactions [Abstract]
Trade receivables	10,419
Yeongwol Energy Station Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	830	858	814
REC purchase	14,256	14,875	16,408
Outstanding balances for related party transactions [Abstract]
Trade receivables	7,068	7,064
Trade payables		229
DS POWER Co., Ltd. [Member]
Disclosure of transactions between related parties [Line Items]
Service sales	5,819	35,133	106,183
Outstanding balances for related party transactions [Abstract]
Trade receivables	340	1,775
Korea Development Bank [Member]
Disclosure of transactions between related parties [Line Items]
Electricity sales	3,239	3,102	4,039
Dividend paid	418,407	654,829	96,087
Interest income	1,685	3,164	2,402
Interest expense	4,573	8,231	₩ 21,719
Outstanding balances for related party transactions [Abstract]
Non-trade receivables and others	501,029	217,481
Non-trade payables and others	200	408
Accrued interest income	204	672
Derivative assets	569	25,306
Derivative liabilities	₩ 22,398	₩ 3,278

Loans transactions between rela

Loans transactions between related parties (Details) ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	₩ 112,583
Changes in Loans receivable transactions between related parties [Abstract]
Loans	63,346
Collection	(29,390)
Others	(20,284)
Ending balance	126,255
Hyundai Energy [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	2,465
Changes in Loans receivable transactions between related parties [Abstract]
Ending balance	2,465
Hyundai Energy [Member] | Accumulated impairment [Member]
Changes in Loans receivable transactions between related parties [Abstract]
Others	(2,465)
Ending balance	(2,465)
Gunsan Bio Energy Co., Ltd. [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	9,396
Changes in Loans receivable transactions between related parties [Abstract]
Ending balance	9,396
KNOC Nigerian East & West Oil [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	29,282
Changes in Loans receivable transactions between related parties [Abstract]
Loans	169
Others	(3,110)
Ending balance	26,341
KNOC Nigerian East & West Oil [Member] | Accumulated impairment [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	(18,191)
Changes in Loans receivable transactions between related parties [Abstract]
Others	1,640
Ending balance	(16,551)
PT Wampu Electric Power [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	14,022
Changes in Loans receivable transactions between related parties [Abstract]
Loans	905
Others	(1,639)
Ending balance	13,288
PT. Cirebon Electric Power [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	26,733
Changes in Loans receivable transactions between related parties [Abstract]
Loans	2,199
Collection	(7,876)
Others	(5,620)
Ending balance	15,436
Xe-Pian Xe-Namnoy Power [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	1,413
Changes in Loans receivable transactions between related parties [Abstract]
Ending balance	1,413
Daehan Wind Power PSC [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	683
Changes in Loans receivable transactions between related parties [Abstract]
Loans	640
Others	(112)
Ending balance	1,211
Datang Chifeng Renewable Power [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	16,344
Changes in Loans receivable transactions between related parties [Abstract]
Collection	(7,647)
Others	(1,452)
Ending balance	7,245
Kelar S.A [Member] | Gross carrying amount [Member]
Changes in Loans receivable transactions between related parties [Abstract]
Loans	54,631
Collection	(3,568)
Others	(4,443)
Ending balance	46,620
KEPCO SPC Power Corporation [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	27,795
Changes in Loans receivable transactions between related parties [Abstract]
Collection	(7,803)
Others	(2,743)
Ending balance	17,249
KODE NOVUS II LLC [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	4,532
Changes in Loans receivable transactions between related parties [Abstract]
Others	(514)
Ending balance	4,018
KODE NOVUS II LLC [Member] | Accumulated impairment [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	(4,532)
Changes in Loans receivable transactions between related parties [Abstract]
Others	514
Ending balance	(4,018)
Chester Solar IV SpA [Member] | Gross carrying amount [Member]
Changes in Loans receivable transactions between related parties [Abstract]
Loans	4,802
Others	(195)
Ending balance	4,607
Rabigh Electricity Company [Member] | Gross carrying amount [Member]
Disclosure of Loans transactions between related parties [Line Items]
Beginning balance	2,641
Changes in Loans receivable transactions between related parties [Abstract]
Collection	(2,496)
Others	₩ (145)

Borrowings transactions between

Borrowings transactions between related parties (Details) - Korea Development Bank [Member] ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)
Facility [Member]
Disclosure of Borrowings transactions between related parties [Line Items]
Beginning balance	₩ 207,993
Changes in Borrowings transactions between related parties [Abstract]
Borrowings	27,324
Repayment	(141,434)
Ending balance	93,883
Others [Member]
Disclosure of Borrowings transactions between related parties [Line Items]
Beginning balance	5,663
Changes in Borrowings transactions between related parties [Abstract]
Repayment	(754)
Ending balance	4,909
Operating funds [Member]
Disclosure of Borrowings transactions between related parties [Line Items]
Beginning balance	37,000
Changes in Borrowings transactions between related parties [Abstract]
Borrowings	49,000
Repayment	(25,000)
Ending balance	61,000
Syndicated Loan [Member]
Disclosure of Borrowings transactions between related parties [Line Items]
Beginning balance	6,075
Changes in Borrowings transactions between related parties [Abstract]
Borrowings	11,855
Others	(1,629)
Ending balance	₩ 16,301

Guarantees provided between the

Guarantees provided between the related parties (Details) ر.س in Thousands, $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)		Dec. 31, 2017USD ($)		Dec. 31, 2017SAR (ر.س)
Performance guarantees1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Electric Power Corporation		Korea Electric Power Corporation		Korea Electric Power Corporation
Name of Guarantee	Shuweihat Asia Operation & Maintenance Company		Shuweihat Asia Operation & Maintenance Company		Shuweihat Asia Operation & Maintenance Company
Name of Principal obligor	SAPCO		SAPCO		SAPCO
Amount of guarantees | $			$ 11,000
Performance guarantees2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Electric Power Corporation		Korea Electric Power Corporation		Korea Electric Power Corporation
Name of Guarantee	KNOC Nigerian East Oil Co., Ltd. and KNOC Nigerian West Oil Co., Ltd.		KNOC Nigerian East Oil Co., Ltd. and KNOC Nigerian West Oil Co., Ltd.		KNOC Nigerian East Oil Co., Ltd. and KNOC Nigerian West Oil Co., Ltd.
Name of Principal obligor	Korea National Oil Corporation (Nigerian government)		Korea National Oil Corporation (Nigerian government)		Korea National Oil Corporation (Nigerian government)
Amount of guarantees | $			$ 34,650
Performance guarantees and others1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Electric Power Corporation		Korea Electric Power Corporation		Korea Electric Power Corporation
Name of Guarantee	Rabigh Operation & Maintenance Company Limited		Rabigh Operation & Maintenance Company Limited		Rabigh Operation & Maintenance Company Limited
Name of Principal obligor	RABEC		RABEC		RABEC
Amount of guarantees | $			$ 1,387
Bidding guarantees [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Electric Power Corporation		Korea Electric Power Corporation		Korea Electric Power Corporation
Name of Guarantee	Nghi Son 2 Power Ltd.		Nghi Son 2 Power Ltd.		Nghi Son 2 Power Ltd.
Name of Principal obligor	SMBC Ho Chi Minh		SMBC Ho Chi Minh		SMBC Ho Chi Minh
Amount of guarantees | $			$ 10,000
Debt guarantees1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Electric Power Corporation		Korea Electric Power Corporation		Korea Electric Power Corporation
Name of Guarantee	Barakah One Company		Barakah One Company		Barakah One Company
Name of Principal obligor	Export-Import Bank of Korea and others		Export-Import Bank of Korea and others		Export-Import Bank of Korea and others
Amount of guarantees | $			$ 900,000
Performance guarantees and others2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Electric Power Corporation		Korea Electric Power Corporation		Korea Electric Power Corporation
Name of Guarantee	Barakah One Company		Barakah One Company		Barakah One Company
Name of Principal obligor	Export-Import Bank of Korea and others		Export-Import Bank of Korea and others		Export-Import Bank of Korea and others
Amount of guarantees | $			$ 3,404,275
Collateralized money invested1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Cheongna Energy Co., Ltd.		Cheongna Energy Co., Ltd.		Cheongna Energy Co., Ltd.
Name of Principal obligor	KEB Hana Bank and others		KEB Hana Bank and others		KEB Hana Bank and others
Amount of guarantees	₩ 27,211
Guarantees for supplemental funding and others1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.	[1]	Korea Western Power Co., Ltd.	[1]	Korea Western Power Co., Ltd.	[1]
Name of Guarantee	Cheongna Energy Co., Ltd.	[1]	Cheongna Energy Co., Ltd.	[1]	Cheongna Energy Co., Ltd.	[1]
Name of Principal obligor	KEB Hana Bank and others	[1]	KEB Hana Bank and others	[1]	KEB Hana Bank and others	[1]
Amount of guarantees	₩ 0	[1]
Payment guarantees for business reserve [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Xe-Pian Xe-Namnoy Power Co., Ltd.		Xe-Pian Xe-Namnoy Power Co., Ltd.		Xe-Pian Xe-Namnoy Power Co., Ltd.
Name of Principal obligor	Krung Thai Bank		Krung Thai Bank		Krung Thai Bank
Amount of guarantees | $			$ 2,500
Collateralized money invested2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Xe-Pian Xe-Namnoy Power Co., Ltd.		Xe-Pian Xe-Namnoy Power Co., Ltd.		Xe-Pian Xe-Namnoy Power Co., Ltd.
Name of Principal obligor	Krung Thai Bank		Krung Thai Bank		Krung Thai Bank
Amount of guarantees | $			$ 62,253
Impounding bonus guarantees [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Xe-Pian Xe-Namnoy Power Co., Ltd.		Xe-Pian Xe-Namnoy Power Co., Ltd.		Xe-Pian Xe-Namnoy Power Co., Ltd.
Name of Principal obligor	SK E&C		SK E&C		SK E&C
Amount of guarantees | $			$ 5,000
Performance guarantees and others3 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Rabigh Operation & Maintenance Company Limited		Rabigh Operation & Maintenance Company Limited		Rabigh Operation & Maintenance Company Limited
Name of Principal obligor	Saudi Arabia British Bank		Saudi Arabia British Bank		Saudi Arabia British Bank
Amount of guarantees | ر.س					ر.س 5,600
Collateralized money invested3 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Daegu Photovoltaic Co., Ltd.		Daegu Photovoltaic Co., Ltd.		Daegu Photovoltaic Co., Ltd.
Name of Principal obligor	Korea Development Bank		Korea Development Bank		Korea Development Bank
Amount of guarantees	₩ 1,230
Collateralized money invested4 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Dongducheon Dream Power Co., Ltd.		Dongducheon Dream Power Co., Ltd.		Dongducheon Dream Power Co., Ltd.
Name of Principal obligor	Kookmin Bank and others		Kookmin Bank and others		Kookmin Bank and others
Amount of guarantees	₩ 53,233
Collateralized money invested5 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	PT. Mutiara Jawa		PT. Mutiara Jawa		PT. Mutiara Jawa
Name of Principal obligor	Woori Bank		Woori Bank		Woori Bank
Amount of guarantees | $			$ 2,610
Collateralized money invested6 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Heang Bok Do Si Photovoltaic Power Co., Ltd.		Heang Bok Do Si Photovoltaic Power Co., Ltd.		Heang Bok Do Si Photovoltaic Power Co., Ltd.
Name of Principal obligor	Nonghyup Bank		Nonghyup Bank		Nonghyup Bank
Amount of guarantees	₩ 194
Collateralized money invested7 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.		Korea Western Power Co., Ltd.
Name of Guarantee	Shin Pyeongtaek Power Co., Ltd.		Shin Pyeongtaek Power Co., Ltd.		Shin Pyeongtaek Power Co., Ltd.
Name of Principal obligor	Kookmin Bank		Kookmin Bank		Kookmin Bank
Amount of guarantees	₩ 43,920
Collateralized money invested8 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	Busan Shinho Solar Power Co., Ltd.		Busan Shinho Solar Power Co., Ltd.		Busan Shinho Solar Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 2,100
Collateralized money invested9 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	Seokmun Energy Co., Ltd.		Seokmun Energy Co., Ltd.		Seokmun Energy Co., Ltd.
Name of Principal obligor	Kookmin Bank and others		Kookmin Bank and others		Kookmin Bank and others
Amount of guarantees	₩ 15,370
Collateralized money invested10 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	Chun-cheon Energy Co., Ltd.		Chun-cheon Energy Co., Ltd.		Chun-cheon Energy Co., Ltd.
Name of Principal obligor	Kookmin Bank and others		Kookmin Bank and others		Kookmin Bank and others
Amount of guarantees	₩ 52,700
Guarantees for supplemental funding1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.	[1]	Korea East-West Power Co., Ltd.	[1]	Korea East-West Power Co., Ltd.	[1]
Name of Guarantee	Chun-cheon Energy Co., Ltd.	[1]	Chun-cheon Energy Co., Ltd.	[1]	Chun-cheon Energy Co., Ltd.	[1]
Name of Principal obligor	Kookmin Bank and others	[1]	Kookmin Bank and others	[1]	Kookmin Bank and others	[1]
Amount of guarantees	₩ 60,270	[1]
Collateralized money invested11 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	Honam Wind Power Co., Ltd.		Honam Wind Power Co., Ltd.		Honam Wind Power Co., Ltd.
Name of Principal obligor	Shinhan Bank and others		Shinhan Bank and others		Shinhan Bank and others
Amount of guarantees	₩ 3,480
Collateralized money invested12 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	GS Donghae Electric Power Co., Ltd.		GS Donghae Electric Power Co., Ltd.		GS Donghae Electric Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 204,000
Collateralized money invested13 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	Yeonggwangbaeksu Wind Power Co., Ltd.		Yeonggwangbaeksu Wind Power Co., Ltd.		Yeonggwangbaeksu Wind Power Co., Ltd.
Name of Principal obligor	Kookmin Bank and others		Kookmin Bank and others		Kookmin Bank and others
Amount of guarantees	₩ 3,000
Collateralized money invested14 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	Yeonggwang Wind Power Co., Ltd.		Yeonggwang Wind Power Co., Ltd.		Yeonggwang Wind Power Co., Ltd.
Name of Principal obligor	KEB Hana Bank and others		KEB Hana Bank and others		KEB Hana Bank and others
Amount of guarantees	₩ 15,375
Debt guarantees2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	PT. Tanjung Power Indonesia		PT. Tanjung Power Indonesia		PT. Tanjung Power Indonesia
Name of Principal obligor	The Bank of Tokyo-Mitsubishi and others		The Bank of Tokyo-Mitsubishi and others		The Bank of Tokyo-Mitsubishi and others
Amount of guarantees | $			$ 46,983
Other guarantees [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.		Korea East-West Power Co., Ltd.
Name of Guarantee	PT. Tanjung Power Indonesia		PT. Tanjung Power Indonesia		PT. Tanjung Power Indonesia
Name of Principal obligor	PT Adaro Indonesia		PT Adaro Indonesia		PT Adaro Indonesia
Amount of guarantees | $			$ 3,150
Performance guarantees3 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	EWP Barbados 1 SRL		EWP Barbados 1 SRL		EWP Barbados 1 SRL
Name of Guarantee	Jamaica Public Service Company Limited		Jamaica Public Service Company Limited		Jamaica Public Service Company Limited
Name of Principal obligor	Societe Generale		Societe Generale		Societe Generale
Amount of guarantees | $			$ 14,400
Guarantees for supplemental funding and others2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	EWP Barbados 1 SRL	[1],[2]	EWP Barbados 1 SRL	[1],[2]	EWP Barbados 1 SRL	[1],[2]
Name of Guarantee	Jamaica Public Service Company Limited	[1],[2]	Jamaica Public Service Company Limited	[1],[2]	Jamaica Public Service Company Limited	[1],[2]
Name of Principal obligor	JCSD Trustee Services Limited and others	[1],[2]	JCSD Trustee Services Limited and others	[1],[2]	JCSD Trustee Services Limited and others	[1],[2]
Amount of guarantees | $			$ 60,000	[1],[2]
Collateralized money invested15 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	KNH Solar Co., Ltd.		KNH Solar Co., Ltd.		KNH Solar Co., Ltd.
Name of Principal obligor	Shinhan Bank and Kyobo Life Insurance Co., Ltd.		Shinhan Bank and Kyobo Life Insurance Co., Ltd.		Shinhan Bank and Kyobo Life Insurance Co., Ltd.
Amount of guarantees	₩ 1,296
Performance guarantees and guarantees for supplemental funding and others1 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	KNH Solar Co., Ltd.	[1]	KNH Solar Co., Ltd.	[1]	KNH Solar Co., Ltd.	[1]
Name of Principal obligor	Shinhan Bank and Kyobo Life Insurance Co., Ltd.	[1]	Shinhan Bank and Kyobo Life Insurance Co., Ltd.	[1]	Shinhan Bank and Kyobo Life Insurance Co., Ltd.	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested16 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Daeryun Power Co., Ltd.		Daeryun Power Co., Ltd.		Daeryun Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 25,477
Guarantees for supplemental funding and others3 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	Daeryun Power Co., Ltd.	[1]	Daeryun Power Co., Ltd.	[1]	Daeryun Power Co., Ltd.	[1]
Name of Principal obligor	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested17 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Changjuk Wind Power Co., Ltd.		Changjuk Wind Power Co., Ltd.		Changjuk Wind Power Co., Ltd.
Name of Principal obligor	Shinhan Bank		Shinhan Bank		Shinhan Bank
Amount of guarantees	₩ 3,801
Guarantees for supplemental funding2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	Changjuk Wind Power Co., Ltd.	[1]	Changjuk Wind Power Co., Ltd.	[1]	Changjuk Wind Power Co., Ltd.	[1]
Name of Principal obligor	Shinhan Bank	[1]	Shinhan Bank	[1]	Shinhan Bank	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested18 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Daegu Green Power Co., Ltd.		Daegu Green Power Co., Ltd.		Daegu Green Power Co., Ltd.
Name of Principal obligor	Shinhan Bank		Shinhan Bank		Shinhan Bank
Amount of guarantees	₩ 46,226
Performance guarantees4 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Kelar S.A		Kelar S.A		Kelar S.A
Name of Principal obligor	KEB Hana Bank, SMBC, Mizuho Bank and others		KEB Hana Bank, SMBC, Mizuho Bank and others		KEB Hana Bank, SMBC, Mizuho Bank and others
Amount of guarantees | $			$ 63,707
Collateralized money invested19 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	DS Power Co., Ltd.		DS Power Co., Ltd.		DS Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 2,900
Guarantees for supplemental funding and others4 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	DS Power Co., Ltd.	[1]	DS Power Co., Ltd.	[1]	DS Power Co., Ltd.	[1]
Name of Principal obligor	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested20 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Pyeongchang Wind Power Co., Ltd.		Pyeongchang Wind Power Co., Ltd.		Pyeongchang Wind Power Co., Ltd.
Name of Principal obligor	Woori Bank and Shinhan Bank		Woori Bank and Shinhan Bank		Woori Bank and Shinhan Bank
Amount of guarantees	₩ 3,875
Performance guarantees and guarantees for supplemental funding and others2 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	Pyeongchang Wind Power Co., Ltd.	[1]	Pyeongchang Wind Power Co., Ltd.	[1]	Pyeongchang Wind Power Co., Ltd.	[1]
Name of Principal obligor	Woori Bank and Shinhan Bank	[1]	Woori Bank and Shinhan Bank	[1]	Woori Bank and Shinhan Bank	[1]
Amount of guarantees	₩ 0	[1]
Guarantees for supplemental funding and others5 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	Taebaek Wind Power Co., Ltd.	[1]	Taebaek Wind Power Co., Ltd.	[1]	Taebaek Wind Power Co., Ltd.	[1]
Name of Principal obligor	Shinhan Bank	[1]	Shinhan Bank	[1]	Shinhan Bank	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested21 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Jeongam Wind Power Co., Ltd		Jeongam Wind Power Co., Ltd		Jeongam Wind Power Co., Ltd
Name of Principal obligor	SK Securities Co., Ltd.		SK Securities Co., Ltd.		SK Securities Co., Ltd.
Amount of guarantees	₩ 5,580
Guarantees for supplemental funding and others6 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	Jeongam Wind Power Co., Ltd	[1]	Jeongam Wind Power Co., Ltd	[1]	Jeongam Wind Power Co., Ltd	[1]
Name of Principal obligor	SK Securities Co., Ltd.	[1]	SK Securities Co., Ltd.	[1]	SK Securities Co., Ltd.	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested22 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.		Korea Southern Power Co., Ltd.
Name of Guarantee	Naepo Green Energy Co., Ltd.		Naepo Green Energy Co., Ltd.		Naepo Green Energy Co., Ltd.
Name of Principal obligor	Hana Financial Investment Co., Ltd. and others		Hana Financial Investment Co., Ltd. and others		Hana Financial Investment Co., Ltd. and others
Amount of guarantees	₩ 29,200
Guarantees for supplemental funding and others7 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]	Korea Southern Power Co., Ltd.	[1]
Name of Guarantee	Naepo Green Energy Co., Ltd.	[1]	Naepo Green Energy Co., Ltd.	[1]	Naepo Green Energy Co., Ltd.	[1]
Name of Principal obligor	Hana Financial Investment Co., Ltd. and others	[1]	Hana Financial Investment Co., Ltd. and others	[1]	Hana Financial Investment Co., Ltd. and others	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested23 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	KEPCO Engineering & Construction Company, Inc.		KEPCO Engineering & Construction Company, Inc.		KEPCO Engineering & Construction Company, Inc.
Name of Guarantee	DS Power Co., Ltd.		DS Power Co., Ltd.		DS Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 15,000
Collateralized money invested24 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.
Name of Guarantee	Hyundai Green Power Co., Ltd.		Hyundai Green Power Co., Ltd.		Hyundai Green Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 87,003
Guarantees for supplemental funding and others8 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.	[1]	Korea Midland Power Co., Ltd.	[1]	Korea Midland Power Co., Ltd.	[1]
Name of Guarantee	Hyundai Green Power Co., Ltd.	[1]	Hyundai Green Power Co., Ltd.	[1]	Hyundai Green Power Co., Ltd.	[1]
Name of Principal obligor	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]
Amount of guarantees	₩ 0	[1]
Debt guarantees3 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.
Name of Guarantee	PT. Cirebon Electric Power		PT. Cirebon Electric Power		PT. Cirebon Electric Power
Name of Principal obligor	Mizuho Bank		Mizuho Bank		Mizuho Bank
Amount of guarantees | $			$ 11,550
Debt guarantees4 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.
Name of Guarantee	PT Wampu Electric Power		PT Wampu Electric Power		PT Wampu Electric Power
Name of Principal obligor	SMBC		SMBC		SMBC
Amount of guarantees | $			$ 5,068
Collateralized money invested25 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.
Name of Guarantee	Gangwon Wind Power Co., Ltd.		Gangwon Wind Power Co., Ltd.		Gangwon Wind Power Co., Ltd.
Name of Principal obligor	IBK and others		IBK and others		IBK and others
Amount of guarantees	₩ 7,409
Collateralized money invested26 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.		Korea Midland Power Co., Ltd.
Name of Guarantee	YaksuESS Co., Ltd		YaksuESS Co., Ltd		YaksuESS Co., Ltd
Name of Principal obligor	Hanwha Life Insurance Co., Ltd.		Hanwha Life Insurance Co., Ltd.		Hanwha Life Insurance Co., Ltd.
Amount of guarantees	₩ 210
Guarantees for supplemental funding and others9 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Midland Power Co., Ltd.	[1]	Korea Midland Power Co., Ltd.	[1]	Korea Midland Power Co., Ltd.	[1]
Name of Guarantee	YaksuESS Co., Ltd	[1]	YaksuESS Co., Ltd	[1]	YaksuESS Co., Ltd	[1]
Name of Principal obligor	Hanwha Life Insurance Co., Ltd.	[1]	Hanwha Life Insurance Co., Ltd.	[1]	Hanwha Life Insurance Co., Ltd.	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested27 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.
Name of Guarantee	Hyundai Energy Co., Ltd.		Hyundai Energy Co., Ltd.		Hyundai Energy Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 47,067
Performance guarantees and guarantees for supplemental funding and others3 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea South-East Power Co., Ltd.	[1]	Korea South-East Power Co., Ltd.	[1]	Korea South-East Power Co., Ltd.	[1]
Name of Guarantee	Hyundai Energy Co., Ltd.	[1]	Hyundai Energy Co., Ltd.	[1]	Hyundai Energy Co., Ltd.	[1]
Name of Principal obligor	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]	Korea Development Bank and others	[1]
Amount of guarantees	₩ 78,600	[1]
Collateralized money invested28 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.
Name of Guarantee	RES Technology AD		RES Technology AD		RES Technology AD
Name of Principal obligor	UniCredit Bulbank and others		UniCredit Bulbank and others		UniCredit Bulbank and others
Amount of guarantees	₩ 15,595
Collateralized money invested29 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.
Name of Guarantee	ASM-BG Investicii AD		ASM-BG Investicii AD		ASM-BG Investicii AD
Name of Principal obligor	UniCredit Bulbank and others		UniCredit Bulbank and others		UniCredit Bulbank and others
Amount of guarantees	₩ 16,101
Guarantees for supplemental funding and others10 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea South-East Power Co., Ltd.	[1],[3]	Korea South-East Power Co., Ltd.	[1],[3]	Korea South-East Power Co., Ltd.	[1],[3]
Name of Guarantee	Express Solar-light Power Generation Co., Ltd.	[1],[3]	Express Solar-light Power Generation Co., Ltd.	[1],[3]	Express Solar-light Power Generation Co., Ltd.	[1],[3]
Name of Principal obligor	Woori Bank	[1],[3]	Woori Bank	[1],[3]	Woori Bank	[1],[3]
Amount of guarantees	₩ 2,500	[1],[3]
Collateralized money invested30 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.		Korea South-East Power Co., Ltd.
Name of Guarantee	S-Power Co., Ltd.		S-Power Co., Ltd.		S-Power Co., Ltd.
Name of Principal obligor	Korea Development Bank and others		Korea Development Bank and others		Korea Development Bank and others
Amount of guarantees	₩ 132,300
Guarantees for supplemental funding and others11 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	KOSEP USA, INC.	[1]	KOSEP USA, INC.	[1]	KOSEP USA, INC.	[1]
Name of Guarantee	KODE NOVUS II LLC	[1]	KODE NOVUS II LLC	[1]	KODE NOVUS II LLC	[1]
Name of Principal obligor	Korea Development Bank	[1]	Korea Development Bank	[1]	Korea Development Bank	[1]
Amount of guarantees	₩ 0	[1]
Guarantees for supplemental funding and others12 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	KOSEP USA, INC.	[1]	KOSEP USA, INC.	[1]	KOSEP USA, INC.	[1]
Name of Guarantee	KODE NOVUS I LLC	[1]	KODE NOVUS I LLC	[1]	KODE NOVUS I LLC	[1]
Name of Principal obligor	Export-Import Bank of Korea and others	[1]	Export-Import Bank of Korea and others	[1]	Export-Import Bank of Korea and others	[1]
Amount of guarantees	₩ 0	[1]
Collateralized money invested31 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Hydro & Nuclear Power Co., Ltd.		Korea Hydro & Nuclear Power Co., Ltd.		Korea Hydro & Nuclear Power Co., Ltd.
Name of Guarantee	Yeongwol Energy Station Co., Ltd.		Yeongwol Energy Station Co., Ltd.		Yeongwol Energy Station Co., Ltd.
Name of Principal obligor	Meritz Fire & Marine Insurance Co., Ltd.		Meritz Fire & Marine Insurance Co., Ltd.		Meritz Fire & Marine Insurance Co., Ltd.
Amount of guarantees	₩ 1,400
Collateralized money invested32 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Hydro & Nuclear Power Co., Ltd.		Korea Hydro & Nuclear Power Co., Ltd.		Korea Hydro & Nuclear Power Co., Ltd.
Name of Guarantee	Noeul Green Energy Co., Ltd.,		Noeul Green Energy Co., Ltd.,		Noeul Green Energy Co., Ltd.,
Name of Principal obligor	KEB Hana Bank and others		KEB Hana Bank and others		KEB Hana Bank and others
Amount of guarantees	₩ 1,740
Collateralized money invested33 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	Korea Hydro & Nuclear Power Co., Ltd.		Korea Hydro & Nuclear Power Co., Ltd.		Korea Hydro & Nuclear Power Co., Ltd.
Name of Guarantee	Busan Green Energy Co., Ltd.		Busan Green Energy Co., Ltd.		Busan Green Energy Co., Ltd.
Name of Principal obligor	Shinhan Bank and others		Shinhan Bank and others		Shinhan Bank and others
Amount of guarantees	₩ 5,243
Collateralized money invested34 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	KEPCO Plant Service & Engineering Co., Ltd.		KEPCO Plant Service & Engineering Co., Ltd.		KEPCO Plant Service & Engineering Co., Ltd.
Name of Guarantee	Incheon New Power Co., Ltd.		Incheon New Power Co., Ltd.		Incheon New Power Co., Ltd.
Name of Principal obligor	Shinhan Bank		Shinhan Bank		Shinhan Bank
Amount of guarantees	₩ 8,160
Guarantees for supplemental funding and others13 [Member]
Disclosure of Guarantees provided between the related parties [Line Items]
Name of Primary guarantor	KEPCO Plant Service & Engineering Co., Ltd.	[1]	KEPCO Plant Service & Engineering Co., Ltd.	[1]	KEPCO Plant Service & Engineering Co., Ltd.	[1]
Name of Guarantee	Incheon New Power Co., Ltd.	[1]	Incheon New Power Co., Ltd.	[1]	Incheon New Power Co., Ltd.	[1]
Name of Principal obligor	Shinhan Bank	[1]	Shinhan Bank	[1]	Shinhan Bank	[1]
Amount of guarantees	₩ 0	[1]
[1]	The Company guarantees to provide supplemental funding for business with respect to excessive business expenses or insufficient repayment of borrowings.
[2]	This includes a guarantee for the shareholder’s capital payment in connection with the business of 190MW gas complex thermal power plant in Jamaica. EWP (Barbados) 1 SRL’s capital contribution amount is USD 6,400 thousand and the total amount of guarantees is USD 27,000 thousand which consists of USD 12,000 thousand of EWP (Barbados) 1 SRL’s contribution obligation and USD 15,000 thousand of SJEH’s portion (50%) of contribution obligation.
[3]	The Company has granted the right to Hana Financial Investment Co., Ltd., as an agent for the creditors to Express Solar-light Power Generation Co., Ltd. (“ESPG”), to the effect that in the event of acceleration of ESPG’s payment obligations under certain borrowings to such creditors, Hana Financial may demand the Company to dispose of shares in ESPG held by the Company and apply the resulting proceeds to repayment of ESPG’s obligations.

Derivatives transactions betwee

Derivatives transactions between related parties (Details) - 12 months ended Dec. 31, 2017 - Korea Development Bank [Member] $ in Thousands, ₩ in Millions	KRW (₩)	USD ($)
Cross Currency Interest Rate Contract 1 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Contract year	2016~2019	2016~2019
Pay, Contract Amount | ₩	₩ 105,260
Receive, Contract Amount | $		$ 100,000
Contract Interest rate Pay	2.48%	2.48%
Contract Interest rate Receive	2.38%	2.38%
Contract exchange rate	1,052.60	1,052.60
Cross Currency Interest Rate Contract 2 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Contract year	2015~2025	2015~2025
Pay, Contract Amount | ₩	₩ 111,190
Receive, Contract Amount | $		$ 100,000
Contract Interest rate Pay	2.62%	2.62%
Contract Interest rate Receive	3.25%	3.25%
Contract exchange rate	1,111.90	1,111.90
Cross Currency Interest Rate Contract 3 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Contract year	2017~2022	2017~2022
Pay, Contract Amount | ₩	₩ 111,610
Receive, Contract Amount | $		$ 100,000
Contract Interest rate Pay	2.31%	2.31%
Contract Interest rate Receive	3.13%	3.13%
Contract exchange rate	1,116.10	1,116.10
Cross Currency Interest Rate Contract 4 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Contract year	2017~2020	2017~2020
Pay, Contract Amount | ₩	₩ 114,580
Receive, Contract Amount | $		$ 100,000
Contract Interest rate Pay	1.75%	1.75%
Contract Interest rate Receive	2.38%	2.38%
Contract exchange rate	1,145.80	1,145.80
Cross Currency Interest Rate Contract 5 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Contract year	2016~2021	2016~2021
Pay, Contract Amount | ₩	₩ 121,000
Receive, Contract Amount | $		$ 100,000
Contract Interest rate Pay	2.15%	2.15%
Contract Interest rate Receive	2.50%	2.50%
Contract exchange rate	1,210	1,210
Cross Currency Interest Rate Contract 6 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Contract year	2017~2022	2017~2022
Pay, Contract Amount | ₩	₩ 113,300
Receive, Contract Amount | $		$ 100,000
Contract Interest rate Pay	1.95%	1.95%
Contract Interest rate Receive	2.63%	2.63%
Contract exchange rate	1,133	1,133
Cross Currency Forward Contract 1 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Pay, Contract Amount | ₩	₩ 104,849
Receive, Contract Amount | $		$ 100,000
Contract exchange rate	1,048.49	1,048.49
Contract date	Dec. 27, 2017	Dec. 27, 2017
Matrurity date	Jul. 12, 2021	Jul. 12, 2021
Cross Currency Forward Contract 2 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Pay, Contract Amount | ₩	₩ 11,950
Receive, Contract Amount | $		$ 11
Contract exchange rate	1,086.35	1,086.35
Contract date	Dec. 14, 2017	Dec. 14, 2017
Matrurity date	Jan. 10, 2018	Jan. 10, 2018
Cross Currency Forward Contract 3 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Pay, Contract Amount | ₩	₩ 15,130
Receive, Contract Amount | $		$ 14
Contract exchange rate	1,080.70	1,080.70
Contract date	Dec. 20, 2017	Dec. 20, 2017
Matrurity date	Jan. 16, 2018	Jan. 16, 2018
Cross Currency Forward Contract 4 [Member]
Disclosure of Derivatives transactions between related parties [Line Items]
Pay, Contract Amount | ₩	₩ 11,782
Receive, Contract Amount | $		$ 11
Contract exchange rate	1,071.10	1,071.10
Contract date	Dec. 28, 2017	Dec. 28, 2017
Matrurity date	Jan. 31, 2018	Jan. 31, 2018

Key management personnel compen

Key management personnel compensation (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Key management personnel compensation [Abstract]
Salaries	₩ 1,271	₩ 1,463	₩ 1,271
Employee benefits	54	33	59
Total	₩ 1,325	₩ 1,496	₩ 1,330

Significant non-cash investing

Significant non-cash investing and financing transactions (Details) - KRW (₩) ₩ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Non-Cash Transactions [Abstract]
Transfer from construction-in-progress to other assets	₩ 13,676,233	₩ 19,971,599	₩ 10,491,054
Recognition of asset retirement cost and related provision for decommissioning costs	2,494,802	470,941	699,673
Transfer from provision for disposal of spent nuclear fuel to accrued expenses	₩ 342,861	₩ 283,675	₩ 491,755

Commitments for Expenditure (De

Commitments for Expenditure (Details) - KRW (₩) ₩ in Millions	Dec. 31, 2017	Dec. 31, 2016
Purchase of switch (25.8kV Eco) 11,395 [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	₩ 40,226	₩ 40,226
Commitments for Expenditure balance		28,072
Purchase of switch (25.8kV Eco) 12,450 [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	50,526
Commitments for Expenditure balance	35,494
Purchase of cable (PVC,1C,2000SQ) 153,000M and others (Shin-Bupyung-Youngseo) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	50,256	50,256
Commitments for Expenditure balance	42,857	50,256
Purchase of cable (PVC, 1C, 2500SQ) 103,374M and others (Bukdangjin-Shintangjung) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	42,500	42,500
Commitments for Expenditure balance	29,987	42,500
Purchase of GIS (362KV 6300A 63KA) 23CB – YoungseoS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	34,500
Commitments for Expenditure balance	34,500
Purchase of GIS (362KV 6300A 63KA) 26CB – Shin-gosungS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	36,950	36,950
Commitments for Expenditure balance		19,897
Purchase of GIS (362KV 6300A 63KA) 26CB – HwasungS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	40,000
Commitments for Expenditure balance	29,231
Purchase of GIS (362KV 6300A 63KA) 27CB – KwangyangS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	37,476	37,476
Commitments for Expenditure balance	18,044	27,760
Purchase of GIS (362KV 6300A 63KA) and 1 other 18CB – BukbusanS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	34,000	34,000
Commitments for Expenditure balance		20,766
Purchase of GIS (800KV 8000A 50KA) 10CB – Shin-JungbuS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	63,730	63,730
Commitments for Expenditure balance	44,955	63,730
Purchase of transformer (765/345/23kV 666.7MVA, 2TANK) 6 units – Shin-JungbuS/S [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	37,500	37,500
Commitments for Expenditure balance	37,500	37,500
Purchase of cable (TR CNCE-W/AL,1C,400SQ) 4,500,000M [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	71,986	71,986
Commitments for Expenditure balance		50,593
Purchase of Concrete Poles (10M, 350KGF) 104,755 and 6 others [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	129,175	129,175
Commitments for Expenditure balance		105,905
Purchase of cable (TR CNCE-W/AL,1C,400SQ) 4,645,000M [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	78,076
Commitments for Expenditure balance	76,762
Purchase of Concrete Poles (10M, 350KGF) 121,900 and 6 others [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	133,387
Commitments for Expenditure balance	112,981
Advanced E-Type low voltage electricity meter 1,600,000 units [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	65,408
Commitments for Expenditure balance	64,592
Purchase of Ground Switch (44-D-A125, 600AX4) and 1 other 4,016 units [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	56,482
Commitments for Expenditure balance	55,990
Construction of Shin-Kori units (#3,4) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	7,363,514	6,856,150
Commitments for Expenditure balance	93,637
Construction of Shin-Kori units (#5,6) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	8,625,387	8,625,387
Commitments for Expenditure balance	6,757,146	7,286,503
Construction of Shin-Hanwool units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	7,982,342	7,982,342
Commitments for Expenditure balance	1,015,813	1,157,700
Construction of Shin-Hanwool units (#3,4) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	8,261,818	8,261,818
Commitments for Expenditure balance	8,097,056	8,170,896
Construction of Yeosu thermal power units (#1) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	174,291	174,291
Commitments for Expenditure balance		1,139
Other 27 contracts [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	262,400	430,204
Commitments for Expenditure balance	114,041	222,555
Purchase of main machine for construction of Seoul Combined units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	361,203	360,500
Commitments for Expenditure balance	99,031	300,663
Construction of Seoul Combined units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	227,685	225,205
Commitments for Expenditure balance	60,568	129,589
Electricity construction of Shin-Boryeong units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	379,115	354,740
Commitments for Expenditure balance		26,878
Purchase of smoke eliminating machine for construction of Shin-Boryeong units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	169,544	121,093
Commitments for Expenditure balance	36,417	2,023
Purchase of coal handling machine for construction of Shin-Boryeong units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	146,353	146,353
Commitments for Expenditure balance		3,543
Service of designing Shin-Boryeong units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	127,810	126,038
Commitments for Expenditure balance	16,371	24,333
Purchase of main machine for construction of Shin-Boryeong units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	866,065	851,132
Commitments for Expenditure balance	4,981	10,746
Construction of Shin-Boryeong units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	316,190	288,438
Commitments for Expenditure balance	23,100	17,828
Purchase of furnace for construction of Shin-Seocheon thermal power plant [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	302,030
Commitments for Expenditure balance	222,555
Purchase of turbine generator for construction of Shin-Seocheon thermal power plant [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	104,402
Commitments for Expenditure balance	83,522
Electricity construction of Shin-Seocheon thermal power plant [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	200,453
Commitments for Expenditure balance	196,993
Purchase of main machine for Jeju LNG combined [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	166,287
Commitments for Expenditure balance	15,409
Purchase of coal handling machine for construction of Taean (#9,10) and IGCC units (conditional contract for installation) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	193,375	192,945
Commitments for Expenditure balance	5,129	38,218
Purchase of furnace for construction of Taean units (#9,10) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	566,945	584,148
Commitments for Expenditure balance	33,817	46,059
Service of designing Taean units (#9,10) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	111,322	109,700
Commitments for Expenditure balance	13,671	18,981
Purchase of desulfurization machine for construction of Taean units (#9,10) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts		92,086
Commitments for Expenditure balance		1,017
Purchase of turbine generator for construction of Taean units (#9,10) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	205,267	228,794
Commitments for Expenditure balance	550	6,788
Purchase of combined generating machine for construction of Taean IGCC units [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	190,923	208,972
Commitments for Expenditure balance		2,102
Purchase of oxygen plant for construction of Taean IGCC units [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	94,564	98,979
Commitments for Expenditure balance	199	221
Service of designing Taean IGCC plant units [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	44,802	44,802
Commitments for Expenditure balance	2,669	3,342
Purchase of gasification plant for construction of Taean IGCC units [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	456,037	457,991
Construction of Samcheok units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	488,347	457,943
Commitments for Expenditure balance		15,851
Purchase of furnace for construction of Samcheok units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	1,082,641	1,091,303
Commitments for Expenditure balance	5,963	51,594
Purchase of coal handling machine for construction of Samcheok units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	304,924	303,273
Commitments for Expenditure balance	52,362	155
Service of designing Samcheok units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	114,047	114,047
Commitments for Expenditure balance	4,745	36,510
Purchase of main equipment [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	168,076	152,286
Commitments for Expenditure balance		39,248
Landscaping construction and other [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	63,110
Construction of yard for Andong natural gas power plant [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	41,961	41,961
Commitments for Expenditure balance		2,600
Purchase of turbine main equipment for Samcheok units (#1,2) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	215,333
Commitments for Expenditure balance	874
Service of designing Dangjin units (#9,10) [Member]
Disclosure of Commitments for Expenditure [Line Items]
Commitments for Expenditure amounts	₩ 122,426	122,426
Commitments for Expenditure balance		₩ 6,125

Contracts for inventory purchas

Contracts for inventory purchase commitment (Details)	12 Months Ended
	Dec. 31, 2017
Concentrate [Member]
Disclosure of contracts for inventory purchase commitment [Line Items]
Periods	2017 ~ 2030
Contracted amounts	39,662 Ton U3O8
Transformed [Member]
Disclosure of contracts for inventory purchase commitment [Line Items]
Periods	2017 ~ 2030
Contracted amounts	22,934 Ton U
Enrichment [Member]
Disclosure of contracts for inventory purchase commitment [Line Items]
Periods	2017 ~ 2029
Contracted amounts	25,530 Ton SWU
Molded [Member]
Disclosure of contracts for inventory purchase commitment [Line Items]
Periods	2017 ~ 2022
Contracted amounts	2,004 Ton U

Litigation Case (Details)

Litigation Case (Details) ₩ in Millions	Dec. 31, 2017KRW (₩)₩ / shares	Dec. 31, 2016KRW (₩)₩ / shares
As the defendant [Member]
Litigation Case [Line Items]
Number of cases | ₩ / shares	565	675
Claim amount | ₩	₩ 477,719	₩ 636,433
As the plaintiff [Member]
Litigation Case [Line Items]
Number of cases | ₩ / shares	185	193
Claim amount | ₩	₩ 690,934	₩ 489,605

Commitments and Contingencies D

Commitments and Contingencies Disclosure (Details) - 12 months ended Dec. 31, 2017 ₱ in Thousands, € in Thousands, ₨ in Thousands, ₨ in Thousands, ر.س in Thousands, ¥ in Thousands, R in Thousands, $ in Thousands, $ in Thousands, ₩ in Millions	KRW (₩)	JPY (¥)	USD ($)	SAR (ر.س)	EUR (€)	INR (₨)	PHP (₱)	ZAR (R)	NPR (₨)	CAD ($)
Commitments on bank-overdraft [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Nonghyup Bank and others
Limited amount | ₩	₩ 1,555,000
Exercised amount | ₩	₩ 68,859
Commitments on bank-daylight overdraft [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Nonghyup Bank
Limited amount | ₩	₩ 280,000
Limit amount available for CP [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Shinhan Bank and others
Limited amount | ₩	₩ 1,100,000
Limit amount available for card1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	KEB Hana Bank and others
Limited amount | ₩	₩ 46,733
Exercised amount | ₩	₩ 2,775
Limit amount available for card2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Banco de Oro
Limited amount | ₱							₱ 5,000
Exercised amount | ₱							₱ 5,000
Loan limit1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Kookmin Bank and others
Limited amount | ₩	₩ 895,500
Exercised amount | ₩	₩ 425,411
Loan limit2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	BNP Paribas and others
Limited amount			$ 1,910,700
Exercised amount			20,000
Certification of payment on L/C [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Woori Bank and others
Limited amount			1,029,604
Exercised amount			233,166
Certification of performance guarantee on contract1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	KEB Hana Bank
Limited amount				ر.س 102,186	€ 1,958					$ 168
Exercised amount				ر.س 87,991	€ 1,958					$ 168
Certification of performance guarantee on contract2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	KEB Hana Bank and others
Limited amount | ₨						₨ 230,515
Exercised amount | ₨						230,515
Certification of performance guarantee on contract3 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Korea Development Bank and others
Limited amount | ¥		¥ 620,000
Exercised amount | ¥		¥ 620,000
Certification of performance guarantee on contract4 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Seoul Guarantee Insurance and others
Limited amount | ₩	₩ 104,248
Exercised amount | ₩	₩ 104,248
Certification of performance guarantee on contract5 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Bank of Kathmandu
Limited amount | ₨									₨ 32,633
Exercised amount | ₨									₨ 32,633
Certification of performance guarantee on contract6 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Standard Chartered and others
Limited amount			753,652
Exercised amount			696,806
Certification of bidding1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	SMBC and others
Limited amount			60,000
Exercised amount			10,230
Certification of bidding2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	ABSA and others
Limited amount | R								R 55,730
Exercised amount | R								R 55,730
Advance payment bond, Warranty bond, Retention bond and others1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	KEB Hana Bank
Limited amount | ₨						157,830
Exercised amount | ₨						157,830
Advance payment bond, Warranty bond, Retention bond and others2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Export-Import Bank of Korea and others
Limited amount			3,850,534
Exercised amount			753,025
Other commitments 1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Nonghyup Bank and others
Limited amount | ₩	₩ 451,521
Exercised amount | ₩	₩ 15,037
Other commitments 2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	KEB Hana Bank and others
Limited amount			1,063,670
Exercised amount			758,536
Inclusive credit1 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Shinhan Bank
Limited amount | ₨						47,489
Exercised amount | ₨						₨ 47,489
Inclusive credit2 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	KEB Hana Bank
Limited amount | ₩	₩ 258,000
Exercised amount | ₩	₩ 117,398
Inclusive credit3 [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	Shinhan Bank and others
Limited amount			32,125
Exercised amount			16,155
Trade finance [Member]
Commitments and Contingencies Disclosure [Line Items]
Financial institutions	BNP Paribas and others
Limited amount			$ 800,000

Assets pledged as collateral (D

Assets pledged as collateral (Details) - 12 months ended Dec. 31, 2017 JD in Thousands, $ in Thousands, ₩ in Millions		KRW (₩)	USD ($)	JOD (JD)
Shareholdings of Gyeongju Wind Power Co., Ltd. [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Korea East-West Power Co., Ltd.
Name of Guarantee		Korea Development Bank and others
Value of collateral		₩ 15,958
Description of assets pledged as collateral description		Collateral for borrowings
Shareholdings of Commerce and Industry Energy Co., Ltd. [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Korea Midland Power Co.,Ltd.
Name of Guarantee		IBK and others
Value of collateral		₩ 13,605
Description of assets pledged as collateral description		Collateral for borrowings
Shareholdings of KOSPO Youngnam Power Co., Ltd. [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Korea Southern Power Co., Ltd.
Name of Guarantee		Shinhan Bank and others
Value of collateral		₩ 40,000
Description of assets pledged as collateral description		Collateral for borrowings
Shareholdings of Mira Power Limited [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Korea South-East Power Co., Ltd.
Name of Guarantee		International Finance Corporation and others
Value of collateral		₩ 44,192
Description of assets pledged as collateral description		Collateral for borrowings
Shareholdings of Gyeonggi Green Energy Co., Ltd. [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Korea Hydro & Nuclear Power Co., Ltd.
Name of Guarantee		Korea Development Bank and others
Value of collateral		₩ 47,000
Description of assets pledged as collateral description		Collateral for borrowings
Factory estate and others [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor	[1]	Gyeonggi Green Energy Co., Ltd.
Name of Guarantee	[1]	Korea Development Bank and others
Value of collateral	[1]	₩ 327,080
Description of assets pledged as collateral description	[1]	Collateral for borrowings
Land, buildings, structures and machinery and others [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Commerce and Industry Energy Co., Ltd.
Name of Guarantee		IBK and others
Value of collateral		₩ 110,500
Description of assets pledged as collateral description		Collateral for borrowings
Cash and Cash Equivalents [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Commerce and Industry Energy Co., Ltd.
Name of Guarantee		IBK and others
Value of collateral		₩ 11,642
Description of assets pledged as collateral description		Collateral for borrowings
Cash and cash equivalents 1 [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Gyeongju Wind Power Co., Ltd.
Name of Guarantee		SK Securities Co.,Ltd. and others
Value of collateral		₩ 8,769
Description of assets pledged as collateral description		Collateral for borrowings
Property, plant and equipment and others [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Gyeongju Wind Power Co., Ltd.
Name of Guarantee		SK Securities Co.,Ltd. and others
Value of collateral		₩ 97,980
Description of assets pledged as collateral description		Collateral for borrowings
Existing or expected trade receivables [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Gyeongju Wind Power Co., Ltd.
Name of Guarantee		SK Securities Co.,Ltd. and others
Value of collateral		₩ 4,800
Description of assets pledged as collateral description		Collateral for borrowings
Bank deposit and insurance claim [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		KOSPO Youngnam Power Co., Ltd.
Name of Guarantee		Shinhan Bank and others
Value of collateral		₩ 396,120
Description of assets pledged as collateral description		Collateral for borrowings
Finance Lease receivable and property, plant and equipment and others [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		Qatrana Electric Power Company
Name of Guarantee		The Islamic Development Bank and others
Value of collateral | JD				JD 188,580
Description of assets pledged as collateral description		Collateral for borrowings
Finance Lease receivable and others [Member]
Disclsoure of assets pledged as collateral [Line Items]
Name of Guarantor		KST Electric Power Company
Name of Guarantee		Scotiabank Inverlat, S.A
Value of collateral | $			$ 2,890,260
Description of assets pledged as collateral description		Collateral for borrowings
[1]	The Company was provided with shares of Gyeonggi Green Energy Co., Ltd., one of its subsidiaries, from the investors as collateral related to long-term borrowings. Additionally, pledge for shares, pledge for transfer of rights of long-term borrowings, pledge for insurance claims and other pledges were established.

Subsequent Events (Details)

Subsequent Events (Details) $ in Thousands, $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2017KRW (₩)	Dec. 31, 2017USD ($)	Dec. 31, 2017HKD ($)
#48-1 corporate bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Mar. 13, 2018
Maturity	Mar. 13, 2021
Interest rate (%)	2.40%	2.40%	2.40%
Amounts issued for the subsequent period	₩ 160,000
#48-2 corporate bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Mar. 13, 2018
Maturity	Mar. 13, 2023
Interest rate (%)	2.70%	2.70%	2.70%
Amounts issued for the subsequent period	₩ 20,000
#48-3 corporate bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Mar. 13, 2018
Maturity	Mar. 13, 2028
Interest rate (%)	2.86%	2.86%	2.86%
Amounts issued for the subsequent period	₩ 30,000
#48-4 corporate bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Mar. 13, 2018
Maturity	Mar. 13, 2048
Interest rate (%)	2.94%	2.94%	2.94%
Amounts issued for the subsequent period	₩ 90,000
Global bond 9 [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Hydro & Nuclear Power Co., Ltd.
Issue date	Mar. 13, 2018
Maturity	Mar. 13, 2028
Interest rate (%)	3.35%	3.35%	3.35%
Amounts issued for the subsequent period | $			$ 1,650,000
Asset backed short-term bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea South-East Power Co., Ltd.
Issue date	Jan. 24, 2018
Maturity	Apr. 10, 2018
Interest rate (%)	1.79%	1.79%	1.79%
Amounts issued for the subsequent period	₩ 190,000
#41-1 non-guaranteed corporate bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Midland Power Co., Ltd.
Issue date	Feb. 20, 2018
Maturity	Feb. 20, 2023
Interest rate (%)	2.72%	2.72%	2.72%
Amounts issued for the subsequent period	₩ 60,000
#41-2 non-guaranteed corporate bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Midland Power Co., Ltd.
Issue date	Feb. 20, 2018
Maturity	Feb. 20, 2028
Interest rate (%)	2.92%	2.92%	2.92%
Amounts issued for the subsequent period	₩ 130,000
#43-1 non-guaranteed bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Southern Power Co., Ltd.
Issue date	Jan. 11, 2018
Maturity	Jan. 11, 2021
Interest rate (%)	2.32%	2.32%	2.32%
Amounts issued for the subsequent period	₩ 120,000
#43-2 non-guaranteed bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Southern Power Co., Ltd.
Issue date	Jan. 11, 2018
Maturity	Jan. 11, 2023
Interest rate (%)	2.57%	2.57%	2.57%
Amounts issued for the subsequent period	₩ 20,000
#43-3 non-guaranteed bond [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Southern Power Co., Ltd.
Issue date	Jan. 11, 2018
Maturity	Jan. 11, 2028
Interest rate (%)	2.76%	2.76%	2.76%
Amounts issued for the subsequent period	₩ 60,000
Non-guaranteed foreign currency bond (Global bond 18) [Member]
Subsequent Events - Issuance of bonds [Line Items]
company name	Korea Southern Power Co., Ltd.
Issue date	Jan. 29, 2018
Maturity	Jan. 29, 2021
Interest rate (%)	3.00%	3.00%	3.00%
Amounts issued for the subsequent period | $		$ 400,000