ASE Technology Holding (ASX) 20-F 28 Mar 18 2017 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information - shares	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018
Document - Document and Entity Information [Abstract]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	ASX
Entity Registrant Name	ADVANCED SEMICONDUCTOR ENGINEERING INC
Entity Central Index Key	1,122,411
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		8,739,734,964

Consolidated Balance Sheets

Consolidated Balance Sheets $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
CURRENT ASSETS
Cash and cash equivalents	$ 46,078,066	$ 1,554,591	$ 38,392,524
Financial assets at fair value through profit or loss - current	5,223,067	176,217	3,069,812
Available-for-sale financial assets - current	89,159	3,008	266,696
Trade receivables, net	55,200,706	1,862,372	51,145,557
Other receivables	1,051,955	35,491	665,480
Current tax assets	260,542	8,790	471,752
Inventories	24,260,911	818,519	21,438,062
Inventories related to real estate business	9,819,516	331,293	24,187,515
Other financial assets - current	472,340	15,936	558,686
Other current assets	2,482,010	83,738	2,593,575
Total current assets	144,938,272	4,889,955	142,789,659
NON-CURRENT ASSETS
Available-for-sale financial assets - non-current	1,123,006	37,888	1,028,338
Investments accounted for using the equity method	48,753,751	1,644,863	49,824,690
Property, plant and equipment	135,168,406	4,560,338	143,880,241
Investment properties	8,119,436	273,935
Goodwill	9,934,494	335,172	10,490,309
Other intangible assets	1,406,865	47,465	1,617,261
Deferred tax assets	4,001,821	135,014	4,536,924
Other financial assets - non-current	1,170,500	39,491	1,320,381
Long-term prepayments for lease	8,851,330	298,628	2,237,033
Other non-current assets	454,391	15,330	205,740
Total non-current assets	218,984,000	7,388,124	215,140,917
TOTAL	363,922,272	12,278,079	357,930,576
CURRENT LIABILITIES
Short-term borrowings	17,962,471	606,021	20,955,522
Financial liabilities at fair value through profit or loss - current	677,430	22,855	1,763,660
Trade payables	41,672,233	1,405,946	35,803,984
Other payables	21,377,887	721,251	21,522,034
Current tax liabilities	7,619,328	257,062	6,846,350
Current portion of bonds payable	6,161,197	207,868	9,658,346
Current portion of long-term borrowings	8,261,625	278,732	6,567,565
Other current liabilities	4,644,566	156,699	3,852,113
Total current liabilities	108,376,737	3,656,434	106,969,574
NON-CURRENT LIABILITIES
Bonds payable	16,981,583	572,928	27,341,557
Long-term borrowings	27,145,003	915,823	46,547,998
Deferred tax liabilities	4,961,487	167,392	4,856,549
Net defined benefit liabilities	3,936,685	132,817	4,172,253
Other non-current liabilities	1,210,590	40,843	1,201,480
Total non-current liabilities	54,235,348	1,829,803	84,119,837
Total effect on liabilities	162,612,085	5,486,237	191,089,411
Share capital
Shares subscribed in advance	134,593	4,541	203,305
Total share capital	87,380,787	2,948,070	79,568,040
Capital surplus	40,624,328	1,370,591	22,266,500
Retained earnings
Legal reserve	16,765,066	565,623	14,597,032
Special reserve	3,353,938	113,156	3,353,938
Unappropriated earnings	53,599,541	1,808,352	44,188,554
Total retained earnings	73,718,545	2,487,131	62,139,524
Other equity	(6,311,089)	(212,925)	(1,840,937)
Treasury shares	(7,292,513)	(246,036)	(7,292,513)
Equity attributable to owners of the Company	188,120,058	6,346,831	154,840,614
NON-CONTROLLING INTERESTS	13,190,129	445,011	12,000,551
Total effect on equity	201,310,187	6,791,842	166,841,165
TOTAL	363,922,272	12,278,079	357,930,576
Ordinary shares [member]
Share capital
Total share capital	$ 87,246,194	$ 2,943,529	$ 79,364,735

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016TWD ($)$ / shares	Dec. 31, 2015TWD ($)$ / shares
OPERATING REVENUES	$ 290,441,208	$ 9,798,961	$ 274,884,107	$ 283,302,536
OPERATING COSTS	237,708,937	8,019,870	221,696,922	233,167,308
GROSS PROFIT	52,732,271	1,779,091	53,187,185	50,135,228
OPERATING EXPENSES
Selling and marketing expenses	3,308,992	111,639	3,473,586	3,588,472
General and administrative expenses	12,458,054	420,312	11,662,082	10,724,568
Research and development expenses	11,746,613	396,309	11,391,147	10,937,566
Total operating expenses	27,513,659	928,260	26,526,815	25,250,606
OTHER OPERATING INCOME AND EXPENSES, NET	108,556	3,662	(800,280)	(251,529)
PROFIT FROM OPERATIONS	25,327,168	854,493	25,860,090	24,633,093
NON-OPERATING INCOME AND EXPENSES
Other income	707,754	23,878	589,236	815,778
Other gains and losses	6,259,453	211,183	2,276,544	1,748,795
Finance costs	(1,799,494)	(60,712)	(2,261,075)	(2,312,143)
Share of the profit of associates and joint ventures	525,782	17,739	1,503,910	126,265
Total non-operating income and expenses	5,693,495	192,088	2,108,615	378,695
PROFIT BEFORE INCOME TAX	31,020,663	1,046,581	27,968,705	25,011,788
INCOME TAX EXPENSE	6,523,603	220,094	5,390,844	4,311,073
PROFIT FOR THE YEAR	24,497,060	826,487	22,577,861	20,700,715
Items that will not be reclassified subsequently to profit or loss:
Remeasurement of defined benefit obligation	205,344	6,928	(417,181)	(62,911)
Share of other comprehensive income of associates and joint ventures	7,249	245	(49,794)	(37,748)
Income tax relating to items that will not be reclassified subsequently	(51,217)	(1,728)	73,637	11,002
Items that will not be reclassified subsequently to profit or loss	161,376	5,445	(393,338)	(89,657)
Items that may be reclassified subsequently to profit or loss:
Exchange differences on translating foreign operations	(5,287,734)	(178,399)	(6,445,643)	(63,509)
Unrealized gain (loss) on available-for-sale financial assets	224,036	7,559	(248,599)	10,451
Share of other comprehensive income (loss) of associates and joint ventures	264,389	8,920	(871,679)	(4,832)
Items that may be reclassified subsequently to profit or loss	(4,799,309)	(161,920)	(7,565,921)	(57,890)
Other comprehensive loss for the year, net of income tax	(4,637,933)	(156,475)	(7,959,259)	(147,547)
TOTAL COMPREHENSIVE INCOME FOR THE YEAR	19,859,127	670,012	14,618,602	20,553,168
PROFIT FOR THE YEAR ATTRIBUTABLE TO:
Owners of the Company	22,819,119	769,876	21,324,423	19,732,148
Non-controlling interests	1,677,941	56,611	1,253,438	968,567
PROFIT FOR THE YEAR	24,497,060	826,487	22,577,861	20,700,715
TOTAL COMPREHENSIVE INCOME FOR THE YEAR ATTRIBUTABLE TO:
Owners of the Company	18,524,067	624,969	13,956,976	19,659,081
Non-controlling interests	1,335,060	45,043	661,626	894,087
TOTAL COMPREHENSIVE INCOME FOR THE YEAR	$ 19,859,127	$ 670,012	$ 14,618,602	$ 20,553,168
EARNINGS PER SHARE
Basic | (per share)	$ 2.80	$ 0.09	$ 2.78	$ 2.58
Diluted | (per share)	2.60	0.09	2.33	2.48
American depositary shares [member]
EARNINGS PER SHARE
Basic | (per share)	13.98	0.47	13.91	12.89
Diluted | (per share)	$ 12.98	$ 0.44	$ 11.64	$ 12.38

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity $ in Thousands, $ in Thousands	TWD ($)	USD ($)	Share capital [member]TWD ($)shares	Share capital [member]USD ($)shares	Capital surplus [member]TWD ($)	Capital surplus [member]USD ($)	Legal reserve [member]TWD ($)	Legal reserve [member]USD ($)	Special reserve [member]TWD ($)	Special reserve [member]USD ($)	Unappropriated earnings [member]TWD ($)	Unappropriated earnings [member]USD ($)	Retained earnings [member]TWD ($)	Retained earnings [member]USD ($)	Exchange differences on translating foreign operations [member]TWD ($)	Exchange differences on translating foreign operations [member]USD ($)	Unrealized gain (loss) on available-for-sale financial assets [member]TWD ($)	Unrealized gain (loss) on available-for-sale financial assets [member]USD ($)	Other equity[member]TWD ($)	Other equity[member]USD ($)	Treasury shares [member]TWD ($)	Treasury shares [member]USD ($)	Equity Attributable to Owners of the Company [member]TWD ($)	Equity Attributable to Owners of the Company [member]USD ($)	Non-controlling interests [member]TWD ($)	Non-controlling interests [member]USD ($)
Beginning balance at Dec. 31, 2014	$ 155,691,394		$ 78,715,179		$ 16,013,980		$ 10,289,878		$ 3,353,938		$ 36,000,026		$ 49,643,842		$ 4,540,862		$ 526,778		$ 5,067,640		$ (1,959,107)		$ 147,481,534		$ 8,209,860
Beginning balance, shares at Dec. 31, 2014 | shares			7,861,725,000	7,861,725,000
Equity component of convertible bonds issued by the Company (Note 20)	214,022				214,022																		214,022
Appropriation of earnings
Legal reserve							2,359,267				(2,359,267)
Cash dividends distributed by the Company	(15,589,825)										(15,589,825)		(15,589,825)										(15,589,825)
Appropriated retained earnings	(15,589,825)						2,359,267				(17,949,092)		(15,589,825)										(15,589,825)
Change from investments in associates and joint ventures accounted for using the equity method	150				150																		150
Net profit for the year	20,700,715										19,732,148		19,732,148										19,732,148		968,567
Other comprehensive income (loss) for the year, net of income tax	(147,547)										(86,217)		(86,217)		(48,191)		61,341		13,150				(73,067)		(74,480)
Total comprehensive income (loss)	20,553,168										19,645,931		19,645,931		(48,191)		61,341		13,150				19,659,081		894,087
Acquisition of treasury shares	(5,333,406)																				(5,333,406)		(5,333,406)
Issue of dividends received by subsidiaries from the Company	292,351				292,351																		292,351
Partial disposal of interests in subsidiaries and additional acquisition of majority-owned subsidiaries (Note 30)	8,910,346				7,197,510																		7,197,510		1,712,836
Changes in percentage of ownership interest in subsidiaries					(563,815)																		(563,815)		563,815
Issue of ordinary shares under employee share options	1,074,833		$ 470,481		604,352																		1,074,833
Issue of ordinary shares under employee share options, shares			48,703,000	48,703,000
Cash dividends distributed by subsidiaries	(232,148)																								(232,148)
Additional non-controlling interest arising on issue of employee share options by subsidiaries	344,095																								344,095
Ending balance at Dec. 31, 2015	165,924,980		$ 79,185,660		23,758,550		12,649,145		3,353,938		37,696,865		53,699,948		4,492,671		588,119		5,080,790		(7,292,513)		154,432,435		11,492,545
Ending balance, shares at Dec. 31, 2015 | shares			7,910,428,000	7,910,428,000
Appropriation of earnings
Legal reserve							1,947,887				(1,947,887)
Cash dividends distributed by the Company	(12,476,779)										(12,476,779)		(12,476,779)										(12,476,779)
Appropriated retained earnings	(12,476,779)						1,947,887				(14,424,666)		(12,476,779)										(12,476,779)
Change from investments in associates and joint ventures accounted for using the equity method	95,495				51,959												43,536		43,536				95,495
Net profit for the year	22,577,861										21,324,423		21,324,423										21,324,423		1,253,438
Other comprehensive income (loss) for the year, net of income tax	(7,959,259)										(402,184)		(402,184)		(6,136,294)		(828,969)		(6,965,263)				(7,367,447)		(591,812)
Total comprehensive income (loss)	14,618,602										20,922,239		20,922,239		(6,136,294)		(828,969)		(6,965,263)				13,956,976		661,626
Issue of dividends received by subsidiaries from the Company	233,013				233,013																		233,013
Partial disposal of interests in subsidiaries and additional acquisition of majority-owned subsidiaries (Note 30)					(20,552)						(5,884)		(5,884)										(26,436)		26,436
Changes in percentage of ownership interest in subsidiaries	(2,825,773)				(1,912,887)																		(1,912,887)		(912,886)
Issue of ordinary shares under employee share options	983,117		$ 382,380		600,737																		983,117
Issue of ordinary shares under employee share options, shares			35,756,000	35,756,000
Non-controlling interests arising from acquisition of subsidiaries (After retrospectively adjusted)	42,857																								42,857
Cash dividends distributed by subsidiaries	(237,850)																								(237,850)
Additional non-controlling interest arising on issue of employee share options by subsidiaries	483,503				(444,320)																		(444,320)		927,823
Ending balance at Dec. 31, 2016	166,841,165		$ 79,568,040		22,266,500		14,597,032		3,353,938		44,188,554		62,139,524		(1,643,623)	$ (55,453)	(197,314)		(1,840,937)		(7,292,513)		154,840,614		12,000,551	$ 404,877
Ending balance, shares at Dec. 31, 2016 | shares			7,946,184,000	7,946,184,000
Equity component of convertible bonds issued by the Company (Note 20)	13,900,482		$ 4,242,577	$ 143,137	9,657,905	$ 325,840																	13,900,482
Appropriation of earnings
Legal reserve							2,168,034				(2,168,034)
Cash dividends distributed by the Company	(11,415,198)										(11,415,198)		(11,415,198)										(11,415,198)
Appropriated retained earnings	(11,415,198)						2,168,034				(13,583,232)		(11,415,198)										(11,415,198)
Change from investments in associates and joint ventures accounted for using the equity method	1,490				1,490																		1,490
Net profit for the year	24,497,060	$ 826,487									22,819,119		22,819,119										22,819,119		1,677,941
Other comprehensive income (loss) for the year, net of income tax	(4,637,933)	(156,475)									175,100		175,100		(5,090,036)		619,884		(4,470,152)				(4,295,052)		(342,881)
Total comprehensive income (loss)	19,859,127	670,012									22,994,219		22,994,219		(5,090,036)		619,884		(4,470,152)				18,524,067		1,335,060
Issue of ordinary shares for capital increase by cash	10,290,000		$ 3,000,000		7,290,000																		10,290,000
Issue of ordinary shares for capital increase by cash, shares | shares			300,000,000	300,000,000
Issue of ordinary shares under conversion of bonds, shares | shares			424,258,000	424,258,000
Issue of dividends received by subsidiaries from the Company	200,977				200,977																		200,977
Changes in percentage of ownership interest in subsidiaries					3,055																		3,055		(3,055)
Issue of ordinary shares under employee share options	1,667,759		$ 570,170		1,256,789																		1,826,959		(159,200)
Issue of ordinary shares under employee share options, shares			67,637,000	67,637,000
Cash dividends distributed by subsidiaries	(246,440)																								(246,440)
Additional non-controlling interest arising on issue of employee share options by subsidiaries	210,825				(52,388)																		(52,388)		263,213
Ending balance at Dec. 31, 2017	$ 201,310,187	$ 6,791,842	$ 87,380,787	$ 2,948,070	$ 40,624,328	$ 1,370,591	$ 16,765,066	$ 565,623	$ 3,353,938	$ 113,156	$ 53,599,541	$ 1,808,352	$ 73,718,545	$ 2,487,131	$ (6,733,659)	$ (227,182)	$ 422,570	$ 14,257	$ (6,311,089)	$ (212,925)	$ (7,292,513)	$ (246,036)	$ 188,120,058	$ 6,346,831	$ 13,190,129	$ 445,011
Ending balance, shares at Dec. 31, 2017 | shares			8,738,079,000	8,738,079,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Profit before income tax	$ 31,020,663	$ 1,046,581	$ 27,968,705	$ 25,011,788
Adjustments for:
Depreciation expense	28,747,518	969,890	28,961,614	28,938,770
Amortization expense	457,666	15,441	508,823	579,894
Net loss (gain) on fair value change of financial assets and liabilities at fair value through profit or loss	2,783,902	93,924	(447,559)	(2,472,835)
Finance costs	1,799,494	60,712	2,261,075	2,312,143
Interest income	(306,871)	(10,353)	(230,067)	(242,084)
Dividend income	(59,039)	(1,992)	(26,411)	(396,973)
Compensation cost of employee share options	438,765	14,803	470,788	133,496
Share of profit of associates and joint ventures	(525,782)	(17,739)	(1,503,910)	(126,265)
Loss (gain) on disposal of property, plant and equipment	(348,070)	(11,743)	131,044	126,132
Impairment loss recognized on financial assets	77,101	2,601	91,886	8,232
Reversal of impairment loss on financial assets			(28,022)
Impairment loss recognized on non- financial assets	1,113,499	37,568	1,340,011	610,140
Gain on disposal of subsidiaries	(5,589,457)	(188,578)
Net loss (gain) on foreign currency exchange	(2,356,480)	(79,503)	(407,160)	1,358,777
Others	1,172,005	39,541	900,378	1,242,110
Financial assets held for trading	(226,049)	(7,626)	1,052,111	4,162,522
Trade receivables	(4,066,374)	(137,192)	(6,184,873)	7,982,736
Other receivables	(330,491)	(11,150)	(211,755)	55,112
Inventories	(2,907,848)	(98,106)	3,156,759	(5,128,726)
Other current assets	(781,477)	(26,366)	(24,517)	407,017
Financial liabilities held for trading	(3,874,662)	(130,724)	(2,952,116)	(1,725,606)
Trade payables	4,753,270	160,367	1,665,420	(1,272,717)
Other payables	685,398	23,124	1,380,205	(814,809)
Other current liabilities	211,145	7,124	(2,347,599)	2,545,312
Other operating activities items	27,538	929	(407,143)	(247,024)
Cash generated from operations	51,915,364	1,751,533	55,117,687	63,047,142
Interest received	236,746	7,987	228,509	253,289
Dividend received	1,929,218	65,088	4,043,644	499,918
Interest paid	(1,666,759)	(56,234)	(2,043,870)	(2,067,955)
Income tax paid	(4,983,769)	(168,144)	(5,238,103)	(4,184,089)
Net cash generated from operating activities	47,430,800	1,600,230	52,107,867	57,548,305
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of financial assets designated as at fair value through profit or loss	(61,308,095)	(2,068,424)	(64,853,336)	(100,842,813)
Proceeds on sale of financial assets designated as at fair value through profit or loss	61,601,865	2,078,335	66,472,870	102,139,161
Purchase of available-for-sale financial assets	(902,648)	(30,454)	(1,590,928)	(1,273,510)
Proceeds on sale of available-for-sale financial assets	1,121,517	37,838	867,336	2,761,145
Cash received from return of capital by available-for-sale financial assets	16,175	546	28,927	44,511
Acquisition of associates and joint ventures			(16,041,463)	(35,673,097)
Net cash outflow on acquisition of subsidiaries			(73,437)
Net cash inflow from disposal of subsidiaries	7,020,883	236,872
Payments for property, plant and equipment	(24,699,240)	(833,308)	(26,714,163)	(30,280,124)
Proceeds from disposal of property, plant and equipment	1,488,210	50,210	670,200	243,031
Payments for intangible assets	(337,984)	(11,403)	(513,893)	(491,135)
Proceeds from disposal of intangible assets	34,690	1,170	25,646
Payments for investment properties	(186,522)	(6,293)
Decrease (increase) in other financial assets	236,227	7,970	(1,231,186)	358,266
Increase in other non-current assets	(171,320)	(5,780)	(206,031)	(336,864)
Net cash used in investing activities	(16,086,242)	(542,721)	(43,159,458)	(63,351,429)
CASH FLOWS FROM FINANCING ACTIVITIES
Net repayment of short-term borrowings	(2,038,993)	(68,792)	(10,640,229)	(8,532,792)
Net proceeds from (repayment of) short-term bills payable			(4,348,054)	4,348,054
Proceeds from issue of bonds	8,000,000	269,906	9,000,000	6,136,425
Repayment of bonds payable	(9,123,972)	(307,826)	(10,365,135)
Proceeds from long-term borrowings	35,394,158	1,194,135	62,282,917	39,887,570
Repayment of long-term borrowings	(51,867,539)	(1,749,917)	(52,924,902)	(22,926,660)
Dividends paid	(11,214,221)	(378,348)	(12,243,766)	(15,297,474)
Proceeds from issue of ordinary shares	10,290,000	347,166
Proceeds from exercise of employee share options	1,439,819	48,577	995,832	1,285,102
Payments for acquisition of treasury shares				(5,333,406)
Proceeds from partial disposal of interests in subsidiaries				8,910,346
Decrease in non-controlling interests	(246,440)	(8,314)	(3,063,623)	(232,148)
Other financing activities items	43,761	1,476	219,940	391,322
Net cash generated from (used in) financing activities	(19,323,427)	(651,937)	(21,087,020)	8,636,339
EFFECTS OF EXCHANGE RATE CHANGES ON THE BALANCE OF CASH AND CASH EQUIVALENTS HELD IN FOREIGN CURRENCY	(4,335,589)	(146,275)	(4,720,046)	723,556
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	7,685,542	259,297	(16,858,657)	3,556,771
CASH AND CASH EQUIVALENTS AT THE BEGINNING OF THE YEAR	38,392,524	1,295,294	55,251,181	51,694,410
CASH AND CASH EQUIVALENTS AT THE END OF THE YEAR	$ 46,078,066	$ 1,554,591	$ 38,392,524	$ 55,251,181

General Information

General Information	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
General Information	1. GENERAL INFORMATION Advanced Semiconductor Engineering, Inc. (the “Company”), a corporation incorporated under the laws of Republic of China (the “ROC”), and its subsidiaries (collectively referred to as the “Group”) offer a comprehensive range of semiconductors packaging, testing, and electronic manufacturing services (“EMS”). The Company’s ordinary shares are listed on the Taiwan Stock Exchange (the “TSE”) under the symbol “2311”. Since September 2000, the ordinary shares of the Company have been traded on the New York Stock Exchange (the “NYSE”) under the symbol “ASX” in the form of American Depositary Shares (“ADS”). The ordinary shares of its subsidiary, Universal Scientific Industrial (Shanghai) Co., Ltd (the “USISH”), are listed on the Shanghai Stock Exchange (the “SSE”) under the symbol “601231”. The consolidated financial statements are presented in the Company’s functional currency, New Taiwan dollar (NT$).

Approval of Financial Statement

Approval of Financial Statements	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Approval of Financial Statements	2. APPROVAL OF FINANCIAL STATEMENTS The consolidated financial statements were authorized for issue by the management on March 23, 2018.

Application of New and Revised

Application of New and Revised International Financial Reporting Standards as Issued by the International Accounting Standards Board ("IASB") ( Collectively, "IFRSs")	12 Months Ended
	Dec. 31, 2017
Application of New and Revised International Financial Reporting Standards as Issued by the International Accounting Standards Board ("IASB") ( Collectively, "IFRSs")	3. APPLICATION OF NEW AND REVISED INTERNATIONAL FINANCIAL REPORTING STANDARDS AS ISSUED BY THE INTERNATIONAL ACCOUNTING STANDARDS BOARD (“IASB”) ( collectively, “IFRSs”) a. Amendments to IFRSs that are mandatorily effective for the current year In the current year, the Group has applied the following new, revised or amended standards and interpretations that have been issued and effective: New, Revised or Amended Standards and Interpretations Effective Date Issued by IASB (Note 1) Amendments to IFRSs Annual Improvements to IFRSs: 2014-2016 Cycle Note 2 Amendments to IAS 7 Disclosure Initiative January 1, 2017 Amendments to IAS 12 Recognition of Deferred Tax Assets for Unrealized Losses January 1, 2017 Note 1: The aforementioned new, revised or amended standards and interpretations are effective for annual period beginning on or after the effective dates, unless specified otherwise. Note 2: The amendment to IFRS 12 is retrospectively applied for annual periods beginning on or after January 1, 2017; the amendment to IAS 28 is retrospectively applied for annual periods beginning on or after January 1, 2018. Except the adoption of Amendments to IAS 7 which can be referred to Note 34e, the Group believes that the adoption of the aforementioned new, revised or amended standards and interpretations did not have a material effect on the Group’s accounting policies. b. New, revised or amended standards and interpretations in issue but not yet effective The Group has not applied the following new, revised or amended standards and interpretations that have been issued but are not yet effective: New, Revised or Amended Standards and Interpretations Effective Date Issued by IASB (Note 1) Amendments to IFRSs Annual Improvements to IFRSs 2015-2017 Cycle January 1, 2019 Amendments to IFRS 2 Classification and Measurement of Share-based Payment Transactions January 1, 2018 IFRS 9 Financial Instruments January 1, 2018 Amendments to IFRS 9 and IFRS 7 Mandatory Effective Date of IFRS 9 and Transition Disclosures January 1, 2018 Amendments to IFRS 9 Prepayment Features with Negative Compensation January 1, 2019 Amendments to IFRS 10 and IAS 28 Sale or Contribution of Assets between an Investor and its Associate or Joint Venture To be determined by IASB IFRS 15 Revenue from Contracts with Customers January 1, 2018 Amendments to IFRS 15 Clarifications to IFRS15 Revenue from Contracts with Customers January 1, 2018 IFRS 16 Leases January 1, 2019 Amendments to IAS 19 Plan Amendment, Curtailment or Settlement January 1, 2019 (Note 2) Amendments to IAS 40 Transfers of investment property January 1, 2018 IFRIC 22 Foreign Currency Transactions and Advance Consideration January 1, 2018 Amendments to IAS 28 Long-term Interests in Associate and Joint Venture January 1, 2019 IFRIC 23 Uncertainty over Income Tax Treatments January 1, 2019 Note 1 : The aforementioned new, revised or amended standards and interpretations are effective for annual period beginning on or after the effective dates, unless specified otherwise. Note 2 : The Group shall apply these amendments to plan amendments, curtailments or settlements occurring on or after January 1, 2019. c. Significant changes in accounting policy resulted from new, revised and amended standards and interpretations in issue but not yet effective Except for the following, the Group believes that the adoption of the aforementioned new, revised or amended standards and interpretations will not have a material effect on the Group’s accounting policies. As of the date that the accompanying consolidated financial statements were authorized for issue, the Group continues in evaluating the impact on its financial position and financial performance as a result of the initial adoption of the below standards and interpretations. The related impact will be disclosed when the Group completes the evaluation. 1) IFRS 9 “Financial Instruments” and related amendments Classification, measurement and impairment of financial assets With regards to financial assets, all recognized financial assets that are within the scope of IAS 39 “Financial Instruments: Recognition and Measurement” are subsequently measured at amortized cost or fair value. Under IFRS 9, the requirement for the classification of financial assets is stated below: For the Group’s debt instruments that have contractual cash flows that are solely payments of principal and interest on the principal amount outstanding, their classification and measurement are as follows: a) For debt instruments, if they are held within a business model whose objective is to collect the contractual cash flows, the financial assets are measured at amortized cost and are assessed for impairment continuously with any impairment loss recognized in profit or loss. Interest revenue is recognized in profit or loss by using the effective interest method; b) For debt instruments, if they are held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets, the financial assets are measured at fair value through other comprehensive income (FVTOCI) and are assessed for impairment. Interest revenue is recognized in profit or loss by using the effective interest method, and other gains or losses shall be recognized in other comprehensive income, except for impairment gains or losses and foreign exchange gains and losses. When the debt instruments are derecognized or reclassified, the cumulative gain or loss previously recognized in other comprehensive income is reclassified from equity to profit or loss. Except for above, all other financial assets are measured at fair value through profit or loss. However, the Group may make an irrevocable election to present subsequent changes in the fair value of an equity investment (that is not held for trading) in other comprehensive income, with only dividend income generally recognized in profit or loss. No subsequent impairment assessment is required, and the cumulative gain or loss previously recognized in other comprehensive income cannot be reclassified from equity to profit or loss. The Group analyzed the facts and circumstances of its financial assets that exist at December 31, 2017 and performed the assessment of the impact of IFRS 9 on the classification and measurement of financial assets. Under IFRS 9: a) Unquoted shares and limited partnership classified as available-for-sale will be designated as at fair value through other comprehensive income and the fair value gains or losses accumulated in other equity will be transferred directly to retained earnings instead of being reclassified to profit or loss on disposal. Impairment losses previously recognized and accumulated in retained earnings will be adjusted by the Group to record an increase in retained earnings and a decrease in other equity, unrealized gains or losses on financial assets at fair value through other comprehensive income, since no subsequent impairment assessment is required under IFRS 9; b) Quoted shares classified as available-for-sale will be classified as at fair value through profit or loss under IFRS 9. Open-end mutual funds classified as available-for-sale will be classified as at fair value through profit or loss under IFRS 9 because the contractual cash flows are not solely payments of principal and interest on the principal outstanding and they are not equity instruments. The Group will reclassify unrealized gains or losses on available-for-sale financial assets in other equity to retained earnings; c) Time deposits with original maturity of over three months, pledged time deposits and guarantee deposits will be classified as measured at amortized cost under IFRS 9 because, on initial recognition, the contractual cash flows that are solely payments of principal and interest on the principal outstanding and these investments are held within a business model whose objective is to collect the contractual cash flows; and d) Debt investments with no active market will be classified as at fair value through other comprehensive income under IFRS 9, because, on initial recognition, the contractual cash flows that are solely payments of principal and interest on the principal outstanding and these investments are held within a business model whose objective is achieved both by collecting contractual cash flows and selling financial assets. The Group will adjust those debt investments and other equity, unrealized gains or losses on financial assets at fair value through other comprehensive income, based on their fair value; IFRS 9 requires that impairment loss on financial assets to be recognized by using the “Expected Credit Losses Model”. A loss allowance is required for financial assets measured at amortized cost, investments in debt instruments measured at FVTOCI, lease receivables, contract assets arising from IFRS 15 “Revenue from Contracts with Customers”, certain written loan commitments and financial guarantee contracts. A loss allowance for the 12-month expected credit losses is required for a financial asset if its credit risk has not increased significantly since initial recognition. A loss allowance for full-lifetime expected credit losses is required for a financial asset if its credit risk has increased significantly since initial recognition and is not low. However, a loss allowance for full-lifetime expected credit losses is required for trade receivables that do not constitute a financing transaction. For purchased or originated credit-impaired financial assets, the Group takes into account the expected credit losses on initial recognition in calculating the credit-adjusted effective interest rate. Subsequently, any changes in expected losses are recognized as a loss allowance with a corresponding gain or loss recognized in profit or loss. In general, the Group anticipates that the application of the expected credit losses model of IFRS 9 will result in an earlier recognition of credit losses for financial assets. The Group elects not to restate prior reporting periods when applying the requirements for the classification, measurement and impairment of financial assets under IFRS 9 with the cumulative effect of the initial application recognized at the date of initial application and will provide the disclosures related to the classification and the adjustment information upon initial application of IFRS 9. The anticipated impact on assets, liabilities and equity of retrospective application of the requirements for the classification, measurement and impairment of financial assets on January 1, 2018 is set out below: Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 NT$ NT$ NT$ Impact on assets, liabilities and equity Financial assets at fair value through profit or loss - current $ 5,223,067 $ 89,159 $ 5,312,226 Available-for-sale financial assets - current 89,159 (89,159 ) - Investments accounted for using the equity method 48,753,751 (2,586 ) 48,751,165 (Continued) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 NT$ NT$ NT$ Financial assets at fair value through profit or loss - non-current $ - $ 214,457 $ 214,457 Financial assets at fair value through other comprehensive income - non-current - 1,988,549 1,988,549 Available-for-sale financial assets - non-current 1,123,006 (1,123,006 ) - Other financial assets － 1,170,500 (1,000,000 ) 170,500 Total effect on assets $ 56,359,483 $ 77,414 $ 56,436,897 Retained earnings $ 73,718,545 $ 364,467 $ 74,083,012 Unrealized gain on equity investments at fair value through other comprehensive income - 55,517 55,517 Unrealized gain on available-for-sale financial assets 422,570 (422,570 ) - Unrealized gain on debt investments at fair value through other comprehensive income - 80,000 80,000 Total effect on equity $ 74,141,115 $ 77,414 $ 74,218,529 (Concluded) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Impact on assets, liabilities and equity Financial assets at fair value through profit or loss - current $ 176,217 $ 3,008 $ 179,225 Available-for-sale financial assets - current 3,008 (3,008 ) - Investments accounted for using the equity method 1,644,863 (87 ) 1,644,776 Financial assets at fair value through profit or loss - non-current - 7,235 7,235 Financial assets at fair value through other comprehensive income - non-current - 67,090 67,090 Available-for-sale financial assets - non-current 37,888 (37,888 ) - Other financial assets － 39,491 (33,738 ) 5,753 Total effect on assets $ 1,901,467 $ 2,612 $ 1,904,079 (Continued) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Retained earnings $ 2,487,131 $ 12,297 $ 2,499,428 Unrealized gain on equity investments at fair value through other comprehensive income - 1,873 1,873 Unrealized gain on available-for-sale financial assets 14,257 (14,257 ) - Unrealized gain on debt investments at fair value through other comprehensive income - 2,699 2,699 Total effect on equity $ 2,501,388 $ 2,612 $ 2,504,000 (Concluded) Hedge accounting The main changes in hedge accounting amended the application requirements for hedge accounting to better reflect the entity’s risk management activities. Compared with IAS 39, the main changes include: (1) enhancing types of transactions eligible for hedge accounting, specifically broadening the risk eligible for hedge accounting of non-financial items; (2) changing the way hedging cost of derivative instruments are accounted for to reduce profit or loss volatility; and (3) replacing retrospective effectiveness assessment with the principle of economic relationship between the hedging instrument and the hedged item. The assessment of the Group’s current hedging relationships indicates that they will qualify as continuing hedging relationships upon application of IFRS 9. 2) IFRS 15 “Revenue from Contracts with Customers” and related amendments IFRS 15 establishes principles for recognizing revenue that apply to all contracts with customers, and will supersede IAS 18 “Revenue”, IAS 11 “Construction Contracts” and a number of revenue-related interpretations. When applying IFRS 15, the Group recognizes revenue by applying the following steps: — Identify the contract with the customer; — Identify the performance obligations in the contract; — Determine the transaction price; — Allocate the transaction price to the performance obligations in the contracts; and — Recognize revenue when the Group satisfies a performance obligation. The Group packages bare semiconductors into finished semiconductors and provides testing services according to customers’ agreed specifications. The Group’s aforementioned performances enhance semiconductors customers control as semiconductors are enhanced the significant risks and rewards of ownership of inventories have been transferred to customers. The Group elects to retrospectively apply IFRS 15 to contracts that are not complete on January 1, 2018 and recognize the cumulative effect of retrospectively applying IFRS 15 in the retained earnings on January 1, 2018. In addition, the Group will disclose the difference between the amount that results from applying IFRS 15 and the amount that results from applying current standards for 2018. The anticipated impact on assets, liabilities and equity when retrospectively applying IFRS 15 on January 1, 2018 is detailed below: Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 NT$ NT$ NT$ Inventories $ 24,260,911 $ (1,381,778 ) $ 22,879,133 Contract assets - current - 1,971,107 1,971,107 Investments accounted for using the equity method 48,753,751 40,139 48,793,890 Deferred tax assets 4,001,821 (7,287 ) 3,994,534 Total effect on assets $ 77,016,483 $ 622,181 $ 77,638,664 Current tax liabilities $ 7,619,328 $ 5,078 $ 7,624,406 Deferred tax liabilities 4,961,487 90,071 5,051,558 Total effect on liabilities $ 12,580,815 $ 95,149 $ 12,675,964 Retained earnings $ 73,718,545 $ 521,849 $ 74,240,394 Non-controlling interests 13,190,129 5,183 13,195,312 Total effect on equity $ 86,908,674 $ 527,032 $ 87,435,706 Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Inventories $ 818,519 $ (46,619 ) $ 771,900 Contract assets - current - 66,502 66,502 Investments accounted for using the equity method 1,644,863 1,354 1,646,217 Deferred tax assets 135,014 (246 ) 134,768 Total effect on assets $ 2,598,396 $ 20,991 $ 2,619,387 Current tax liabilities $ 257,062 $ 171 $ 257,233 Deferred tax liabilities 167,392 3,039 170,431 Total effect on liabilities $ 424,454 $ 3,210 $ 427,664 (Continued) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Retained earnings $ 2,487,131 $ 17,606 $ 2,504,737 Non-controlling interests 445,011 175 445,186 Total effect on equity $ 2,932,142 $ 17,781 $ 2,949,923 (Concluded) 3) IFRS 16 “Leases” IFRS 16 sets out the accounting standards for leases that will supersede IAS 17 and a number of related interpretations. Under IFRS 16, if the Group is a lessee, it shall recognize right-of-use assets and lease liabilities for all leases on the consolidated balance sheets except for low-value and short-term leases. The Group may elect to apply the accounting method similar to the accounting for operating lease under IAS 17 to low-value and short-term leases. On the consolidated statements of comprehensive income, the Group should present the depreciation expense charged on the right-of-use asset separately from the interest expense accrued on the lease liabilities; interest is computed by using effective interest method. On the consolidated statements of cash flows, cash payments for the principal portion of the lease liabilities are classified within financing activities; cash payments for the interest portion are classified within operating activities. The application of IFRS 16 is not expected to have a material impact on the accounting of the Group as lessor. When IFRS 16 becomes effective, the Group may elect to apply this Standard either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of the initial application of this Standard recognized at the date of initial application. 4) Amendments to IAS 19 “Plan Amendment, Curtailment or Settlement ” The amendments stipulate that, if a plan amendment, curtailment or settlement occurs, the current service cost and the net interest for the remainder of the annual reporting period are determined using the actuarial assumptions used for the remeasurement of the net defined benefit liabilities (assets). In addition, the amendments clarify the effect of a plan amendment, curtailment or settlement on the requirements regarding the asset ceiling. The amendment shall be applied prospectively.
IFRS9 [member]
Application of New and Revised International Financial Reporting Standards as Issued by the International Accounting Standards Board ("IASB") ( Collectively, "IFRSs")	The anticipated impact on assets, liabilities and equity of retrospective application of the requirements for the classification, measurement and impairment of financial assets on January 1, 2018 is set out below: Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 NT$ NT$ NT$ Impact on assets, liabilities and equity Financial assets at fair value through profit or loss - current $ 5,223,067 $ 89,159 $ 5,312,226 Available-for-sale financial assets - current 89,159 (89,159 ) - Investments accounted for using the equity method 48,753,751 (2,586 ) 48,751,165 (Continued) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 NT$ NT$ NT$ Financial assets at fair value through profit or loss - non-current $ - $ 214,457 $ 214,457 Financial assets at fair value through other comprehensive income - non-current - 1,988,549 1,988,549 Available-for-sale financial assets - non-current 1,123,006 (1,123,006 ) - Other financial assets － 1,170,500 (1,000,000 ) 170,500 Total effect on assets $ 56,359,483 $ 77,414 $ 56,436,897 Retained earnings $ 73,718,545 $ 364,467 $ 74,083,012 Unrealized gain on equity investments at fair value through other comprehensive income - 55,517 55,517 Unrealized gain on available-for-sale financial assets 422,570 (422,570 ) - Unrealized gain on debt investments at fair value through other comprehensive income - 80,000 80,000 Total effect on equity $ 74,141,115 $ 77,414 $ 74,218,529 (Concluded) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Impact on assets, liabilities and equity Financial assets at fair value through profit or loss - current $ 176,217 $ 3,008 $ 179,225 Available-for-sale financial assets - current 3,008 (3,008 ) - Investments accounted for using the equity method 1,644,863 (87 ) 1,644,776 Financial assets at fair value through profit or loss - non-current - 7,235 7,235 Financial assets at fair value through other comprehensive income - non-current - 67,090 67,090 Available-for-sale financial assets - non-current 37,888 (37,888 ) - Other financial assets － 39,491 (33,738 ) 5,753 Total effect on assets $ 1,901,467 $ 2,612 $ 1,904,079 (Continued) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Retained earnings $ 2,487,131 $ 12,297 $ 2,499,428 Unrealized gain on equity investments at fair value through other comprehensive income - 1,873 1,873 Unrealized gain on available-for-sale financial assets 14,257 (14,257 ) - Unrealized gain on debt investments at fair value through other comprehensive income - 2,699 2,699 Total effect on equity $ 2,501,388 $ 2,612 $ 2,504,000
Adoption of IFRS 15 [member]
Application of New and Revised International Financial Reporting Standards as Issued by the International Accounting Standards Board ("IASB") ( Collectively, "IFRSs")	The anticipated impact on assets, liabilities and equity when retrospectively applying IFRS 15 on January 1, 2018 is detailed below: Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 NT$ NT$ NT$ Inventories $ 24,260,911 $ (1,381,778 ) $ 22,879,133 Contract assets - current - 1,971,107 1,971,107 Investments accounted for using the equity method 48,753,751 40,139 48,793,890 Deferred tax assets 4,001,821 (7,287 ) 3,994,534 Total effect on assets $ 77,016,483 $ 622,181 $ 77,638,664 Current tax liabilities $ 7,619,328 $ 5,078 $ 7,624,406 Deferred tax liabilities 4,961,487 90,071 5,051,558 Total effect on liabilities $ 12,580,815 $ 95,149 $ 12,675,964 Retained earnings $ 73,718,545 $ 521,849 $ 74,240,394 Non-controlling interests 13,190,129 5,183 13,195,312 Total effect on equity $ 86,908,674 $ 527,032 $ 87,435,706 Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Inventories $ 818,519 $ (46,619 ) $ 771,900 Contract assets - current - 66,502 66,502 Investments accounted for using the equity method 1,644,863 1,354 1,646,217 Deferred tax assets 135,014 (246 ) 134,768 Total effect on assets $ 2,598,396 $ 20,991 $ 2,619,387 Current tax liabilities $ 257,062 $ 171 $ 257,233 Deferred tax liabilities 167,392 3,039 170,431 Total effect on liabilities $ 424,454 $ 3,210 $ 427,664 (Continued) Carrying Amount as of December 31, 2017 Adjustments Arising from Initial Application Adjusted Carrying Amount as of January 1, 2018 US$ (Note 4) US$ (Note 4) US$ (Note 4) Retained earnings $ 2,487,131 $ 17,606 $ 2,504,737 Non-controlling interests 445,011 175 445,186 Total effect on equity $ 2,932,142 $ 17,781 $ 2,949,923

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Significant Accounting Policies	4. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES a. Statement of Compliance The consolidated financial statements have been prepared in accordance with IFRSs as issued by the IASB. b. Basis of Preparation The consolidated financial statements have been prepared on the historical cost basis except for certain financial instruments that are measured at fair value and net defined benefit liabilities which are measured at the present value of the defined benefit obligation less the fair value of plan assets. The fair value measurements are grouped into Levels 1 to 3 based on the degree to which the fair value measurement inputs are observable and the significance of the inputs to the fair value measurement in its entirety, which are described as follows: 1) Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; 2) Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for an asset or a liability, either directly (i.e. as prices) or indirectly (i.e. derived from prices); and 3) Level 3 inputs are unobservable inputs for an asset or a liability. c. Classification of Current and Non-current Assets and Liabilities Current assets include cash and cash equivalents and those assets held primarily for trading purposes or expected to be realized within twelve months after the balance sheet date, unless the asset is to be used for an exchange or to settle a liability, or otherwise remains restricted, at more than twelve months after the balance sheet date. Current liabilities are obligations incurred for trading purposes or to be settled within twelve months after the balance sheet date and liabilities that do not have an unconditional right to defer settlement for at least twelve months after the balance sheet date. Assets and liabilities that are not classified as current are classified as non-current. The Group engages in the construction business which has an operating cycle of over one year. The normal operating cycle applies when considering the classification of the Group’s construction-related assets and liabilities. d. Basis of Consolidation 1) Principles for preparing consolidated financial statements The consolidated financial statements incorporate the financial statements of the Company and the entities controlled by the Company (i.e. its subsidiaries, including structured entities). Income and expenses of subsidiaries acquired or disposed of during the period are included in the consolidated statement of profit or loss and other comprehensive income from the effective dates of acquisitions up to the effective dates of disposals, as appropriate. When necessary, adjustments are made to the financial statements of subsidiaries to bring their accounting policies into line with those used by the Company. All intra-group transactions, balances, income and expenses are eliminated in full upon consolidation. Total comprehensive income of subsidiaries is attributed to the owners of the Company and to the non-controlling interests even if this results in the non-controlling interests having a deficit balance. Changes in the Group’s ownership interests in subsidiaries that do not result in the Group losing control over the subsidiaries are accounted for as equity transactions. The carrying amounts of the interests of the Group and the non-controlling interests are adjusted to reflect the changes in their relative interests in the subsidiaries. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity and attributed to the owners of the Company. When the Group loses control over a subsidiary, a gain or loss is recognized in profit or loss and is calculated as the difference between (i) the aggregate of the fair value of the consideration received and any investment retained in the former subsidiary at its fair value at the date when control is lost and (ii) the assets (including any goodwill) and liabilities and any non-controlling interests of the former subsidiary at their carrying amounts at the date when control is lost. The Group accounts for all amounts recognized in other comprehensive income in relation to that subsidiary on the same basis as would be required if the Group had directly disposed of the related assets or liabilities. 2) Subsidiaries included in consolidated financial statements were as follows: Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 A.S.E. Holding Limited Holding company Bermuda 100.0 100.0 J & R Holding Limited (“J&R Holding”) Holding company Bermuda 100.0 100.0 Innosource Limited Holding company British Virgin Islands 100.0 100.0 Omniquest Industrial Limited Holding company British Virgin Islands 100.0 100.0 ASE Marketing & Service Japan Co., Ltd. Engaged in marketing and sales services Japan 100.0 100.0 ASE Test, Inc. Engaged in the testing of semiconductors Kaohsiung, ROC 100.0 100.0 USI Inc. (“USIINC”) Engaged in investing activity Nantou, ROC 99.2 99.2 Luchu Development Corporation (“Luchu”) Engaged in the development of real estate properties Taipei, ROC 86.1 86.1 TLJ Intertech Inc. (“TLJ”) Engaged in information software services Taipei, ROC 60.0 60.0 Alto Enterprises Limited Holding company British Virgin Islands 100.0 100.0 Super Zone Holdings Limited Holding company Hong Kong 100.0 100.0 ASE (Kun Shan) Inc. Engaged in the packaging and testing of semiconductors Kun Shan, China 100.0 100.0 ASE Investment (Kun Shan) Limited Holding company Kun Shan, China 100.0 100.0 Advanced Semiconductor Engineering (China) Ltd. Will engage in the packaging and testing of semiconductors Shanghai, China 100.0 100.0 ASE Investment (Labuan) Inc. Holding company Malaysia 100.0 100.0 ASE Test Limited (“ASE Test”) Holding company Singapore 100.0 100.0 ASE (Korea) Inc. (“ASE Korea”) Engaged in the packaging and testing of semiconductors Korea 100.0 100.0 J&R Industrial Inc. Engaged in leasing equipment and investing activity Kaohsiung, ROC 100.0 100.0 ASE Japan Co., Ltd. (“ASE Japan”) Engaged in the packaging and testing of semiconductors Japan 100.0 100.0 ASE (U.S.) Inc. After-sales service and sales support U.S.A. 100.0 100.0 Global Advanced Packaging Technology Limited Holding company British Cayman Islands 100.0 100.0 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 ASE WeiHai Inc. Engaged in the packaging and testing of semiconductors Shandong, China 100.0 100.0 Suzhou ASEN Semiconductors Co., Ltd. (“ASEN”) Engaged in the packaging and testing of semiconductors Suzhou, China 60.0 60.0 Anstock Limited Engaged in financing activity British Cayman Islands 100.0 100.0 Anstock II Limited Engaged in financing activity British Cayman Islands 100.0 100.0 ASE Module (Shanghai) Inc. Absorbed by ASE (Shanghai) Inc. in February 2017 Shanghai, China 100.0 - ASE (Shanghai) Inc. Engaged in the production of substrates Shanghai, China 100.0 100.0 ASE Corporation Holding company British Cayman Islands 100.0 100.0 ASE Mauritius Inc. Holding company Mauritius 100.0 100.0 ASE Labuan Inc. Holding company Malaysia 100.0 100.0 Shanghai Ding Hui Real Estate Development Co., Ltd. Engaged in the development, construction and sale of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Qi Property Management Co., Ltd. Engaged in the management of real estate properties Shanghai, China 100.0 100.0 Advanced Semiconductor Engineering (HK) Limited Engaged in the trading of substrates Hong Kong 100.0 100.0 Shanghai Ding Wei Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Yu Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Fan Department Store Co., Ltd. Engaged in department store business Shanghai, China 100.0 100.0 Kun Shan Ding Yue Real Estate Development Co., Ltd. (“KSDY”) Engaged in the development, construction and leasing of real estate properties and was disposed of in June 2017 (Note 29) Kun Shan, China 100.0 - Kun Shan Ding Hong Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Kun Shan, China 100.0 100.0 Shanghai Ding Xu Property Management Co., Ltd. Engaged in the management of real estate properties, and was established in August 2017 Shanghai, China - 100.0 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 ASE Electronics Inc. Engaged in the production of substrates Kaohsiung, ROC 100.0 100.0 ASE Test Holdings, Ltd. Holding company British Cayman Islands 100.0 100.0 ASE Holdings (Singapore) Pte. Ltd. Holding company Singapore 100.0 100.0 ASE Singapore Pte. Ltd. Engaged in the packaging and testing of semiconductors Singapore 100.0 100.0 ISE Labs, Inc. Engaged in the testing of semiconductors U.S.A. 100.0 100.0 ASE Electronics (M) Sdn. Bhd. Engaged in the packaging and testing of semiconductors Malaysia 100.0 100.0 ASE Assembly & Test (Shanghai) Limited Engaged in the packaging and testing of semiconductors Shanghai, China 100.0 100.0 ASE Trading (Shanghai) Ltd. Engaged in trading activity Shanghai, China 100.0 100.0 Wuxi Tongzhi Microelectronics Co., Ltd. Engaged in the packaging and testing of semiconductors Wuxi, China 100.0 100.0 Huntington Holdings International Co., Ltd. Holding company British Virgin Islands 99.2 99.2 Unitech Holdings International Co., Ltd. Holding company British Virgin Islands 99.2 99.2 Real Tech Holdings Limited Holding company British Virgin Islands 99.2 99.2 Universal ABIT Holding Co., Ltd. In the process of liquidation British Cayman Islands 99.2 99.2 Rising Capital Investment Limited Holding company British Virgin Islands 99.2 99.2 Rise Accord Limited Holding company British Virgin Islands 99.2 99.2 Universal Scientific Industrial (Kunshan) Co., Ltd. Engaged in the manufacturing and sale of computer assistance system and related peripherals Kun Shan, China 99.2 99.2 USI Enterprise Limited (“USIE”) Engaged in the services of investment advisory and warehousing management Hong Kong 97.0 96.9 USISH Engaged in the designing, manufacturing and sale of electronic components Shanghai, China 75.9 75.8 Universal Global Technology Co., Limited Holding company Hong Kong 75.9 75.8 Universal Global Technology (Kunshan) Co., Ltd. Engaged in the designing and manufacturing of electronic components Kun Shan, China 75.9 75.8 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 Universal Global Technology (Shanghai) Co., Ltd. Engaged in the processing and sales of computer and communication peripherals as well as business in import and export of goods and technology Shanghai, China 75.9 75.8 Universal Global Electronics (Shanghai) Co., Ltd. Engaged in the sale of electronic components and telecommunications equipment Shanghai, China 75.9 75.8 Universal Global Industrial Co., Limited Engaged in manufacturing, trading and investing activity Hong Kong 75.9 75.8 Universal Global Scientific Industrial Co., Ltd. (“UGTW”) Engaged in the manufacturing of components of telecomm and cars and provision of related R&D services Nantou, ROC 75.9 75.8 USI America Inc. Engaged in the manufacturing and processing of motherboards and wireless network communication and provision of related technical service. U.S.A. 75.9 75.8 Universal Scientific Industrial De Mexico S.A. De C.V. Engaged in the assembling of motherboards and computer components Mexico 75.9 75.8 USI Japan Co., Ltd. Engaged in the manufacturing and sale of computer peripherals, integrated chip and other related accessories Japan 75.9 75.8 USI Electronics (Shenzhen) Co., Ltd. Engaged in the design, manufacturing and sale of motherboards and computer peripherals Shenzhen, China 75.9 75.8 Universal Scientific Industrial Co., Ltd. (“USI”) Engaged in the manufacturing, processing and sale of computers, computer peripherals and related accessories Nantou, ROC 75.2 75.5 (Concluded) e. Business Combinations Acquisitions of businesses are accounted for using the acquisition method. Acquisition-related costs are generally recognized in profit or loss as they are incurred. Goodwill is measured as the excess of the sum of the consideration transferred, the amount of any non-controlling interests in the acquiree, and the fair value of the acquirer’s previously held equity interest in the acquiree (if any) over the net of the acquisition-date amounts of the identifiable assets acquired and the liabilities assumed. If, after re-assessment, the net of the acquisition-date amounts of the identifiable assets acquired and liabilities assumed exceeds the sum of the consideration transferred, the amount of any non-controlling interests in the acquiree and the fair value of the acquirer’s previously held interest in the acquiree (if any), the excess is recognized immediately in profit or loss as a bargain purchase gain. When a business combination is achieved in stages, the Group’s previously held equity interest in the acquiree is remeasured to its acquisition-date fair value and the resulting gain or loss, if any, is recognized in profit or loss. Amounts arising from interests in the acquiree prior to the acquisition date that have previously been recognized in other comprehensive income are recognized on the same basis as would be required if that interest were directly disposed of by the Group. If the initial accounting for a business combination is incomplete by the end of the reporting period in which the combination occurs, the Group reports provisional amounts for the items for which the accounting is incomplete. Those provisional amounts are adjusted retrospectively during the measurement period, 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. Business combination involving entities under common control is not accounted for by acquisition method but accounted for at the carrying amounts of the entities. Prior period comparative information in the financial statements is restated as if a business combination involving entities under common control had already occurred in that period. f. Foreign Currencies In preparing the financial statements of each individual group entity, transactions in currencies other than the entity’s functional currency (i.e. foreign currencies) are recognized at the rates of exchange prevailing at the dates of the transactions. At each balance sheet date, monetary items denominated in foreign currencies are retranslated at the rates prevailing at that date. Exchange differences on monetary items arising from settlement or translation are recognized in profit or loss in the period in which they arise. Non-monetary items measured at fair value that are denominated in foreign currencies are retranslated at the rates prevailing at the date when the fair value was determined. Exchange differences arising from the retranslation of non-monetary items are included in profit or loss for the period except for exchange differences arising from the retranslation of non-monetary items in respect of which gains and losses are recognized directly in other comprehensive income, in which cases, the exchange differences are also recognized directly in other comprehensive income. Non-monetary items that are measured at historical cost in a foreign currency are translated using the exchange rate at the date of the transaction, and are not retranslated. For the purposes of presenting the consolidated financial statements, the assets and liabilities of the Group’s foreign operations are translated into New Taiwan dollars using exchange rates prevailing at each balance sheet date. Income and expense items are translated at the average exchange rates for the period. The resulting currency translation differences are recognized in other comprehensive income and accumulated in equity attributed to the owners of the Company and non-controlling interests as appropriate. On the disposal of the Group’s entire interest in a foreign operation, or a disposal involving loss of control over a subsidiary that includes a foreign operation, all of the exchange differences accumulated in equity in respect of that operation attributable to the owners of the Company are reclassified to profit or loss. In relation to a partial disposal of a subsidiary that does not result in the Group losing control over the subsidiary, the proportionate share of accumulated exchange differences is re-attributed to the non-controlling interests of the subsidiary and is not recognized in profit or loss. For all other partial disposals, the proportionate share of the accumulated exchange differences recognized in other comprehensive income is reclassified to profit or loss. g. Inventories and Inventories Related to Real Estate Business Inventories, including raw materials (materials received from customers for processing, mainly semiconductor wafers, are excluded from inventories as title and risk of loss remain with the customers), supplies, work in process, finished goods, and materials and supplies in transit are stated at the lower of cost or net realizable value. Inventory write-downs are made by item, except for those that may be appropriate to group items of similar or related inventories. Net realizable value is the estimated selling prices of inventories less all estimated costs of completion and estimated costs necessary to make the sale. Raw materials and supplies are recorded at moving average cost while work in process and finished goods are recorded at standard cost. Inventories related to real estate business include land and buildings held for sale, land held for construction and construction in progress. Land held for development is recorded as land held for construction upon obtaining the title of ownership. Prior to the completion, the borrowing costs directly attributable to construction in progress are capitalized as part of the cost of the asset. Construction in progress is transferred to land and buildings held for sale upon completion. Land and buildings held for sale, construction in progress and land held for construction are stated at the lower of cost or net realizable value and related write-downs are made by item. The amounts received in advance for real estate properties are first recorded as advance receipts and then recognized as revenue when the construction is completed and the title and significant risk of the real estate properties are transferred to customers. Cost of sales of land and buildings held for sale are recognized based on the ratio of property sold to the total property developed. h. Investments in associates and joint ventures An associate is an entity over which the Group has significant influence and that is neither a subsidiary nor an interest in a joint venture. Joint venture is a joint arrangement whereby the Group and other parties that have joint control of the arrangement have rights to the net assets of the arrangement. Under the equity method, investments in an associate and a joint venture are initially recognized at cost and adjusted thereafter to recognize the Group’s share of the profit or loss and other comprehensive income of the associate and joint venture. The Group also recognizes the changes in the Group’s share of equity of associates and joint venture. Any excess of the cost of acquisition over the Group’s share of the fair value of the net identifiable assets and liabilities of an associate or a joint venture at the date of acquisition is recognized as goodwill, which is included within the carrying amount of the investment and is not amortized. Gains and losses resulting from upstream, downstream and sidestream transactions between the Group (including its subsidiaries) and its associates or joint ventures are recognized in the Group’s consolidated financial statements only to the extent of interests in the associates or joint ventures that are not related to the Group. i. Property, Plant and Equipment Except for land which is stated at cost, property, plant and equipment are stated at cost less accumulated depreciation and accumulated impairment. Properties in the course of construction are carried at cost, less any recognized impairment loss. Cost includes professional fees and borrowing costs eligible for capitalization. Such assets are depreciated and classified to the appropriate categories of property, plant and equipment when completed and ready for intended use. Freehold land is not depreciated. Depreciation of property, plant and equipment is recognized using the straight-line method. Each significant part is depreciated separately. If the lease term is shorter than the assets’ useful lives, such assets are depreciated over the lease term. The estimated useful lives, residual values and depreciation method are reviewed at each balance sheet date, with the effect of any changes in estimate accounted for on a prospective basis. On derecognition of an item of property, plant and equipment, the difference between the sales proceeds and the carrying amount of the asset is recognized in profit or loss. j. Investment properties Investment properties are properties held to earn rentals and/or for capital appreciation (including property under construction for such purposes). Investment properties are measured initially at cost, including transaction costs. Subsequent to initial recognition, investment properties are measured at cost less accumulated depreciation and accumulated impairment loss. Depreciation is recognized using the straight-line method. Investment properties under construction are stated at cost less accumulated depreciation and accumulated impairment loss. Cost includes professional fees and, borrowing costs eligible for capitalization. Depreciation of these assets commences when the assets are ready for their intended use. On derecognition of an investment property, the difference between the net disposal proceeds and the carrying amount of the asset is included in profit or loss. k. Goodwill Goodwill arising from an acquisition of a business is carried at cost as established at the date of acquisition of the business less accumulated impairment loss. For the purposes of impairment testing, goodwill is allocated to each of the Group’s cash-generating units or groups of cash-generating units (referred to as “cash-generating units”) that is expected to benefit from the synergies of the combination. A cash-generating unit to which goodwill has been allocated is tested for impairment annually, or more frequently when there is an indication that the unit may be impaired, by comparing its carrying amount, including the attributed goodwill, with its recoverable amount. However, if the goodwill allocated to a cash-generating unit was acquired in a business combination during the current annual period, that unit shall be tested for impairment before the end of the current annual period. If the recoverable amount of the cash-generating unit is less than its carrying amount, the impairment loss is allocated first to reduce the carrying amount of any goodwill allocated to the unit and then pro rata to the other assets of the unit based on the carrying amount of each asset in the unit. Any impairment loss is recognized directly in profit or loss. An impairment loss recognized for goodwill is not reversed in subsequent periods. l. Other Intangible Assets Other intangible assets with finite useful lives acquired separately are initially measured at cost and subsequently measured at cost less accumulated amortization and accumulated impairment loss. Other intangible assets are amortized based on the pattern in which the economic benefits are consumed or using the straight-line method over their estimated useful lives. The estimated useful lives, residual values, and amortization methods are reviewed at each balance sheet date, with the effect of any changes in estimate being accounted for on a prospective basis. Other intangible assets acquired in a business combination and 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, they are measured on the same basis as intangible assets that are acquired separately. On derecognition of an intangible asset, the difference between the net disposal proceeds and the carrying amount of the asset are recognized in profit or loss. m. Impairment of Tangible and Intangible Assets Other than Goodwill At each balance sheet date, the Group reviews the carrying amounts of its tangible and intangible assets, excluding goodwill, 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. When it is not possible to estimate the recoverable amount of an individual asset, the Group estimates the recoverable amount of the cash-generating unit to which the asset belongs. Corporate assets are allocated to the individual cash-generating units on a reasonable and consistent basis of allocation. The recoverable amount is the higher of fair value less costs to sell and value in use. If the recoverable amount of an asset or cash-generating unit is estimated to be less than its carrying amount, the carrying amount of the asset or cash-generating unit is reduced to its recoverable amount, with the resulting impairment loss recognized in profit or loss. When an impairment loss is subsequently reversed, the carrying amount of the asset or cash-generating unit is increased to the revised estimate of its recoverable amount, but only to the extent of 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. n. Financial Instruments Financial assets and financial liabilities are recognized when a group entity becomes a party to the contractual provisions of the instruments. Financial assets and financial liabilities are initially measured at fair value. Transaction costs that are directly attributable to the acquisition or issue of financial assets and financial liabilities (other than financial assets and financial liabilities at fair value through profit or loss) are added to or deducted from the fair value of the financial assets or financial liabilities, as appropriate, on initial recognition. Transaction costs directly attributable to the acquisition of financial assets or financial liabilities at fair value through profit or loss are recognized immediately in profit or loss. 1) Financial assets All regular way purchases or sales of financial assets are recognized or derecognized on a settlement date basis. a) Measurement category The classification of financial assets held by the Group depends on the nature and purpose of the financial assets and is determined at the time of initial recognition. i Financial assets at fair value through profit or loss (“FVTPL”) Financial assets are classified as at FVTPL when the financial assets are either held for trading or they are designated as at FVTPL. A financial asset other than a financial asset 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 asset forms part of a group of financial assets or financial liabilities or both, which is managed and has performance evaluated on a fair value basis, in accordance with the Group’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or • The contract contains one or more embedded derivatives so that the entire hybrid (combined) contract can be designated as at FVTPL. Financial assets at FVTPL are stated at fair value with any gains or losses arising on remeasurement recognized in profit or loss. The net gain or loss recognized in profit or loss incorporates any dividend or interest earned on the financial asset. Fair value is determined in the manner described in Note 34. ii Available-for-sale financial assets Available-for-sale financial assets are non-derivatives that are either designated as available-for-sale or are not classified as (a) loans and receivables, (b) held-to-maturity investments or (c) financial assets at fair value through profit or loss. Available-for-sale financial assets are stated at fair value at each balance sheet date. Changes in the carrying amount of available-for-sale monetary financial assets relating to changes in foreign currency rates, interest income calculated using the effective interest method and dividends on available-for-sale equity investments are recognized in profit or loss. Other changes in the carrying amount of available-for-sale financial assets are recognized in other comprehensive income and accumulated under the heading of unrealized gain (loss) on available-for-sale financial assets. When the investment is disposed of or is determined to be impaired, the cumulative gain or loss previously accumulated in the unrealized gain (loss) on available-for-sale financial assets is reclassified to profit or loss. Dividends on available-for-sale equity instruments are recognized in profit or loss when the Group’s right to receive the dividends is established. iii Loans and receivables Loans and receivables including cash and cash equivalents, trade receivables, other receivables and other financial assets are measured at amortized cost using the effective interest method, less any impairment. Interest income is recognized by applying the effective interest rate, except for short-term receivables when the effect of discounting is immaterial. Cash equivalents are short-term, highly liquid investments that are readily convertible to known amounts of cash and which are subject to an insignificant risk of change in value. b) Impairment of financial assets Financial assets, other than those at FVTPL, are assessed for indicators of impairment at each balance sheet date. 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 assets, the estimated future cash flows of the investments have been affected. For financial assets carried at amortized cost, such as trade receivables and other receivables, assets that are assessed not to be impaired individually are, further, assessed for impairment on a collective basis. The Group assesses the collectability of receivables based on the Group’s past experience of collecting payments and observable changes that correlate with default on receivables. For financial assets carried at amortized cost, the amount of the impairment loss recognized is the difference between the assets’ carrying amounts and the present value of estimated future cash flows, discounted at the financial assets’ original effective interest rates. If, in a subsequent period, the amount of the impairment loss decreases and the decreases can be objectively related to an event occurring after the impairment loss recognized, the previously recognized impairment loss is reversed either directly or by adjusting an allowance account through profit or loss. The reversal shall not result in carrying amounts of financial assets that exceed what the amortized cost would have been at the date the impairment is reversed. For any available-for-sale equity investments, a significant or prolonged decline in the fair value of the security below its cost is considered to be objective evidence of impairment. When an available-for-sale financial asset is considered to be impaired, cumulative gains or losses previously recognized in other comprehensive income are reclassified to profit or loss in the period. In respect of available-for-sale equity securities, impairment loss previously recognized in profit or loss is not reversed through profit or loss

Critical Accounting Judgments a

Critical Accounting Judgments and Key Sources of Estimation Uncertainty	12 Months Ended
	Dec. 31, 2017
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Critical Accounting Judgments and Key Sources of Estimation Uncertainty	5. CRITICAL ACCOUNTING JUDGMENTS AND KEY SOURCES OF ESTIMATION UNCERTAINTY In the application of the Group’s accounting policies, which are described in Note 4, management is required to make judgments, estimates and assumptions about the carrying amounts of assets and liabilities that are not readily apparent from other sources. The estimates and underlying assumptions are based on historical experience and other factors that are considered to be relevant. Actual results may differ from these estimates. The estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimate is revised if the revision affects only that period, or in the period of the revision and future periods if the revision affects both current and future periods.

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2017
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Cash and Cash Equivalents	6. CASH AND CASH EQUIVALENTS December 31 2016 2017 NT$ NT$ US$ (Note 4) Cash on hand $ 6,856 $ 8,404 $ 284 Checking accounts and demand deposits 28,823,763 39,697,319 1,339,316 Cash equivalents 9,561,905 6,372,343 214,991 $ 38,392,524 $ 46,078,066 $ 1,554,591 Cash equivalents include time deposits that are of a short maturity of three months or less from the date of acquisitions, and are highly liquid, readily convertible to known amounts in cash and the risk of changes in values is insignificant. Cash equivalents are held for the purpose of meeting short-term cash commitments rather than for investments or other purposes.

Financial Instruments at Fair V

Financial Instruments at Fair Value Through Profit or Loss	12 Months Ended
	Dec. 31, 2017
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Financial Instruments at Fair Value Through Profit or Loss	7. FINANCIAL INSTRUMENTS AT FAIR VALUE THROUGH PROFIT OR LOSS December 31 2016 2017 NT$ NT$ US$ (Note 4) Financial assets designated as at FVTPL Private-placement convertible bonds $ 100,583 $ 100,496 $ 3,391 Financial assets held for trading Quoted shares $ 1,855,073 $ 4,410,732 $ 148,810 Open-end mutual funds 584,945 589,976 19,905 Forward exchange contracts 66,872 61,325 2,069 Swap contracts 462,339 60,538 2,042 2,969,229 5,122,571 172,826 $ 3,069,812 $ 5,223,067 $ 176,217 Financial liabilities held for trading Swap contracts $ 422,934 $ 652,107 $ 22,001 Forward exchange contracts 108,912 25,323 854 Conversion option, redemption option and put option of convertible bonds (Note 20) 1,213,890 - - Foreign currency option contracts 17,924 - - $ 1,763,660 $ 677,430 $ 22,855 Private-placement convertible bonds included embedded derivative instruments which were not closely related to the host contracts and the Group designated the entire contracts as financial assets at FVTPL on initial recognition. At each balance sheet date, the outstanding swap contracts not accounted for hedge accounting were as follows: Notional Amount Currency Maturity Period (In Thousands) December 31, 2016 Sell NT$/Buy US$ 2017.01-2017.12 NT$59,797,499/US$1,871,000 Sell US$/Buy CNY 2017.03 US$49,904/CNY349,800 Sell US$/Buy JPY 2017.02 US$77,153/JPY8,600,000 Sell US$/Buy NT$ 2017.01 US$61,000/NT$1,958,908 December 31, 2017 Sell NT$/Buy US$ 2018.01-2018.12 NT$53,136,302/US$1,782,400 Sell US$/Buy CNY 2018.01 US$52,948/CNY349,800 Sell US$/Buy JPY 2018.02-2018.03 US$70,324/JPY7,870,000 Sell US$/Buy NT$ 2018.01 US$217,300/NT$6,505,767 At each balance sheet date, the outstanding forward exchange contracts not accounted for hedge accounting were as follow: Notional Amount Currency Maturity Period (In Thousands) December 31, 2016 Sell NT$/Buy US$ 2017.01-2017.02 NT$2,842,330/US$90,000 Sell US$/Buy CNY 2017.01-2017.02 US$70,000/CNY484,805 Sell US$/Buy JPY 2017.01-2017.02 US$43,877/JPY5,063,820 Sell US$/Buy KRW 2017.01 US$35,000/KRW41,012,700 Sell US$/Buy MYR 2017.01-2017.02 US$19,000/MYR84,544 Sell US$/Buy NT$ 2017.01-2017.03 US$190,000/NT$6,099,400 Sell US$/Buy SGD 2017.01-2017.03 US$12,900/SGD18,080 Sell US$/Buy EUR 2017.01 US$281/EUR270 December 31, 2017 Sell NT$/Buy US$ 2018.01 NT$2,389,620/US$80,000 Sell US$/Buy CNY 2018.01-2018.04 US$125,000/CNY828,858 Sell US$/Buy EUR 2018.01 US$10,674/EUR9,000 Sell US$/Buy JPY 2018.01-2018.02 US$45,517/JPY5,111,101 Sell US$/Buy MYR 2018.01-2018.03 US$15,000/MYR61,859 Sell US$/Buy NT$ 2018.01 US$1,000/NT$30,142 Sell US$/Buy SGD 2018.01-2018.02 US$11,300/SGD15,305 At each balance sheet date, the outstanding foreign currency option contracts not accounted for hedge accounting were as follows: Notional Amount Currency Maturity Period (In Thousands) December 31, 2016 Buy US$ Call/CNY Put 2017.08 (Note) US$2,000/CNY13,800 Sell US$ Put/CNY Call 2017.08 (Note) US$1,000/CNY6,900 Note: The contracts will be settled once a month and the counterparty has the right to early terminate the contracts, or the contracts will be early terminated or both parties will have no obligation to settle the contracts when the specific criteria are met.

Available-for-sale Financial As

Available-for-sale Financial Assets	12 Months Ended
	Dec. 31, 2017
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Available-for-sale Financial Assets	8. AVAILABLE-FOR-SALE FINANCIAL ASSETS December 31 2016 2017 NT$ NT$ US$ (Note 4) Unquoted ordinary shares $ 553,350 $ 605,110 $ 20,415 Quoted ordinary shares 146,786 279,791 9,440 Limited partnership 273,372 246,072 8,302 Unquoted preferred shares 78,068 57,367 1,935 Open-end mutual funds 243,458 23,825 804 1,295,034 1,212,165 40,896 Current 266,696 89,159 3,008 Non-current $ 1,028,338 $ 1,123,006 $ 37,888

Trade Receivables, Net

Trade Receivables, Net	12 Months Ended
	Dec. 31, 2017
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Trade Receivables, Net	9. TRADE RECEIVABLES, NET December 31 2016 2017 NT$ NT$ US$ (Note 4) Trade receivables $ 51,199,266 $ 55,265,607 $ 1,864,562 Less: Allowance for doubtful debts 53,709 64,901 2,190 Trade receivables, net $ 51,145,557 $ 55,200,706 $ 1,862,372 The Group’s average credit terms were 30 to 90 days. Allowance for doubtful debts is assessed by reference to the collectability of receivables by evaluating the account aging, historical experience and current financial condition of customers. As of December 31, 2016 and 2017, except that the Group’s five largest customers accounted for 30% and 33% of accounts receivable, respectively, the concentration of credit risk is insignificant for the remaining accounts receivable. Aging of receivables based on the past due date December 31 2016 2017 NT$ NT$ US$ (Note 4) Not past due $ 45,959,876 $ 49,599,512 $ 1,673,398 1 to 30 days 4,467,435 4,986,491 168,235 31 to 90 days 700,122 562,200 18,968 More than 91 days 71,833 117,404 3,961 Total $ 51,199,266 $ 55,265,607 $ 1,864,562 Aging of receivables that were past due but not impaired December 31 2016 2017 NT$ NT$ US$ (Note 4) 1 to 30 days $ 4,449,479 $ 4,942,677 $ 166,757 31 to 90 days 596,647 378,526 12,771 Total $ 5,046,126 $ 5,321,203 $ 179,528 Except for those impaired, the Group had not provided an allowance for doubtful debts on trade receivables at each balance sheet date since there has not been a significant change in credit quality and the amounts were still considered collectible. The Group did not hold any collateral or other credit enhancements over these balances nor did it have a legal right to offset against any amounts owed by the Group to counterparties. Movement of the allowance for doubtful trade receivables Impaired Individually Impaired Collectively Total NT$ NT$ NT$ Balance at January 1, 2015 $ 28,305 $ 55,840 $ 84,145 Impairment losses recognized (reversed) 18,816 (10,584 ) 8,232 Amount written off (7,617 ) (209 ) (7,826 ) Effect of foreign currency exchange differences (458 ) (1,187 ) (1,645 ) Balance at December 31, 2015 39,046 43,860 82,906 Impairment losses reversed (21,501 ) (6,521 ) (28,022 ) Effect of foreign currency exchange differences (1,092 ) (83 ) (1,175 ) Balance at December 31, 2016 16,453 37,256 53,709 Impairment losses recognized 9,527 4,102 13,629 Amounts written off - (34 ) (34 ) Effect of foreign currency exchange differences (850 ) (1,553 ) (2,403 ) Balance at December 31, 2017 $ 25,130 $ 39,771 $ 64,901 Impaired Individually Impaired Collectively Total US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1, 2017 $ 555 $ 1,257 $ 1,812 Impairment losses recognized 322 138 460 Amounts written off - (1 ) (1 ) Effect of foreign currency exchange differences (29 ) (52 ) (81 ) Balance at December 31, 2017 $ 848 $ 1,342 $ 2,190

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
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Inventories	10. INVENTORIES December 31 2016 2017 NT$ NT$ US$ (Note 4) Finished goods $ 6,519,465 $ 6,740,816 $ 227,423 Work in process 2,822,687 3,452,332 116,475 Raw materials 10,850,062 12,625,502 425,962 Supplies 795,093 894,196 30,168 Raw materials and supplies in transit 450,755 548,065 18,491 $ 21,438,062 $ 24,260,911 $ 818,519 The cost of inventories recognized as operating costs for the years ended December 31, 2015, 2016 and 2017 were NT$233,165,722 thousand, NT$219,630,270 thousand (retrospectively adjusted) and NT$237,193,286 thousand (US$8,002,473 thousand), respectively, which included write-downs of inventories at NT$352,011 thousand, NT$451,780 thousand and NT$398,824 thousand (US$13,456 thousand), respectively.

Inventories Related to Real Est

Inventories Related to Real Estate Business	12 Months Ended
	Dec. 31, 2017
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Inventories Related to Real Estate Business	11. INVENTORIES RELATED TO REAL ESTATE BUSINESS December 31 2016 2017 NT$ NT$ US$ (Note 4) Land and buildings held for sale $ 263,526 $ 25,825 $ 871 Construction in progress 22,236,464 8,106,166 273,488 Land held for construction 1,687,525 1,687,525 56,934 $ 24,187,515 $ 9,819,516 $ 331,293 Land and buildings held for sale located in Kun Shan Qiandeng and Shanghai Zhangjiang, China were completed and successively sold. Construction in progress is mainly located on Hutai Road in Shanghai, China and Lidu Road in Kun Shan, China. The capitalized borrowing costs for the years ended December 31, 2015, 2016 and 2017 is disclosed in Note 24. Construction in progress located on Caobao Road in Shanghai was completed in the third quarter of 2017 and immediately leased out for the lease business. As a result, the Group reclassified those buildings and land use right under the line item of “inventories related to real estate - construction in progress” to investment properties of NT$6,971,372 thousand (US$235,201 thousand) and long-term prepayments for lease of NT$5,798,449 thousand (US$195,629 thousand), respectively. Please refer to Note 15. As of December 31, 2016 and 2017, inventories related to real estate business of NT$12,076,154 thousand and NT$9,818,869 thousand (US$331,271 thousand), respectively, are expected to be recovered longer than twelve months. Refer to Note 36 for the carrying amount of inventories related to real estate business that had been pledged by the Group to secure bank borrowings.

Other Financial Assets

Other Financial Assets	12 Months Ended
	Dec. 31, 2017
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Other Financial Assets	12. OTHER FINANCIAL ASSETS December 31 2016 2017 NT$ NT$ US$ (Note 4) Unsecured subordinate corporate bonds $ 1,000,000 $ 1,000,000 $ 33,738 Time deposits with original maturity of over three months 480,736 405,520 13,682 Guarantee deposits 178,103 170,594 5,756 Pledged time deposits (Note 36) 206,530 59,456 2,006 Others (Note 36) 13,698 7,270 245 1,879,067 1,642,840 55,427 Current 558,686 472,340 15,936 Non-current $ 1,320,381 $ 1,170,500 $ 39,491 The annual interest rate of unsecured subordinate corporate bonds was both 3.50% as of December 31, 2016 and 2017.

Investments Accounted for Using

Investments Accounted for Using the Equity Method	12 Months Ended
	Dec. 31, 2017
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Investments Accounted for Using the Equity Method	13. INVESTMENTS ACCOUNTED FOR USING THE EQUITY METHOD December 31 2016 (Retrospectively Adjusted) 2017 NT$ NT$ US$ (Note 4) Investments in associates $ 49,154,140 $ 48,267,237 $ 1,628,449 Investments in joint venture 670,550 486,514 16,414 $ 49,824,690 $ 48,753,751 $ 1,644,863 a. Investments in associates 1) Investments in associates accounted for using the equity method consisted of the following: Carrying Amount as of December 31 2016 (Retrospectively Adjusted) 2017 Operating NT$ NT$ US$ Name of Associate Main Business Location (Note 4) Material associate Siliconware Precision Industries Co., Ltd. (“SPIL”) Engaged in assembly, testing and turnkey services of integrated circuits ROC $ 45,898,225 $ 45,210,371 $ 1,525,316 Associates that are not individually material Deca Technologies Inc. （ ） Holding company and the group engaged in manufacturing, development and marketing of wafer level packaging and interconnect technology British Cayman Islands 1,813,677 1,583,124 53,412 Hung Ching Development & Construction Co. (“HC”) Engaged in the development, construction and leasing of real estate properties ROC 1,156,833 1,248,711 42,129 Hung Ching Kwan Co. (“HCK”) Engaged in the leasing of real estate properties ROC 321,120 309,630 10,447 (continued) Carrying Amount as of December 31 2016 (Retrospectively Adjusted) 2017 Operating NT$ NT$ US$ Name of Associate Main Business Location (Note 4) Advanced Microelectronic Products Inc. (“AMPI”) Engaged in integrated circuit ROC $ 264,434 $ 215,550 $ 7,272 49,454,289 48,567,386 1,638,576 Less: Deferred gain on transfer of land 300,149 300,149 10,127 $ 49,154,140 $ 48,267,237 $ 1,628,449 (concluded) 2) At each balance sheet date, the percentages of ownership held by the Group were as follows: December 31 2016 2017 SPIL 33.29 % 33.29 % DECA 22.07 % 22.04 % HC 26.22 % 26.22 % HCK 27.31 % 27.31 % AMPI 38.76 % 38.76 % 3) In July 2016, the Company acquired 98,490 thousand preferred shares issued by DECA at US$0.608 per share with a total consideration of NT$1,934,062 thousand (US$59,882 thousand). The percentage of ownership was 22.07% and the Company obtained significant influence over DECA. In 2017, the percentage of ownership was decreased to 22.04% since DECA’s share options were exercised. The Company’s subsidiary, ASE Test, Inc., purchased 90,000 thousand ordinary share of AMPI in a private placement with NT$225,000 thousand paid in cash in November 2016. The private-placement ordinary shares were restricted for disposal during a 3-year lock-up period. As a result, the percentage of ownership held by the Group was increased to 38.76%. 4) The Group has successively completed the identification of the difference between the cost of the investments and the Group’s share of the net fair value of DECA and AMPI’s identifiable assets and liabilities in the second quarter and the third quarter in 2017. Therefore, the Group has retrospectively adjusted the comparative consolidated financial statements for prior periods. As of December 31, 2016, the retrospective adjustments are summarized as follows: After Retrospectively Adjusted Before Retrospectively Adjusted NT$ NT$ Investments accounted for using the equity method December 31, 2016 DECA $ 1,813,677 $ 1,820,329 AMPI $ 264,434 $ 266,085 The aforementioned retrospective adjustments are accordingly recorded as a decrease of retained earnings as of December 31, 2016. 5) Fair values (Level 1 inputs in terms of IFRS 13) of investments in associates with available published price quotation are summarized as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) SPIL $ 49,634,805 $ 52,176,190 $ 1,760,330 HC $ 1,310,829 $ 1,695,156 $ 57,191 AMPI $ 307,038 $ 468,572 $ 15,809 6) Summarized financial information in respect of the Group’s material associate The summarized financial information below represents amounts shown in SPIL’s consolidated financial statements prepared in accordance with IFRSs and adjusted by the Group for equity method accounting purposes. December 31 2016 2017 NT$ NT$ US$ (Note 4) Current assets $ 50,451,295 $ 49,065,912 $ 1,655,395 Non-current assets 107,573,251 101,693,417 3,430,952 Current liabilities (41,088,439 ) (26,194,615 ) (883,759 ) Non-current liabilities (17,518,410 ) (27,213,266 ) (918,126 ) Equity $ 99,417,697 $ 97,351,448 $ 3,284,462 Proportion of the Group’s ownership interest in SPIL 33.29 % 33.29 % 33.29 % Net assets attributable to the Group $ 33,096,151 $ 32,408,297 $ 1,093,397 Goodwill 12,802,074 12,802,074 431,919 Carrying amount $ 45,898,225 $ 45,210,371 $ 1,525,316 For the Year Ended December 31 2016 2017 NT$ NT$ US$ (Note 4) Operating revenue $ 85,111,913 $ 83,554,385 $ 2,818,974 Gross profit $ 15,027,247 $ 12,464,792 $ 420,540 Profit before income tax $ 7,351,661 $ 4,347,810 $ 146,687 Net profit for the year $ 5,484,462 $ 2,822,231 $ 95,217 Other comprehensive income (loss) (2,373,532 ) 579,057 19,536 Total comprehensive income for the year $ 3,110,930 $ 3,401,288 $ 114,753 Cash dividends received from SPIL $ 3,941,740 $ 1,815,275 $ 61,244 7) Aggregate information of associates that are not individually material For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) The Group’s share of: Net profit (loss) for the year $ 120,749 $ (139,366 ) $ (190,532 ) $ (6,428 ) Other comprehensive income (loss) for the year (2,916 ) (115,650 ) 59,676 2,013 Total comprehensive income (loss) for the year $ 117,833 $ (255,016 ) $ (130,856 ) $ (4,415 ) b. Investments in joint venture 1) The Group’s investment in a joint venture that was not individually material and accounted for using the equity method consisted of ASE Embedded Electronics Inc. (“ASEEE”). In May 2015, the Group and TDK Corporation (“TDK”) entered into an agreement to establish a joint venture to invest in ASEEE. The Group additionally participated in ASEEE’s cash capital increase with NT$146,903 thousand in September 2016. As of December 31, 2016 and 2017, the percentages of ownership were both 51%. ASEEE are located in ROC and engaged in the production of embedded substrate. According to the joint arrangement, the Group and TDK must act together to direct the relevant operating activities and, as a result, the Group does not control ASEEE. The investment in ASEEE is accounted for using the equity method. 2) Aggregate information of the joint venture that is not individually material For the Year Ended December 31 2016 2017 NT$ NT$ US$ (Note 4) The Group’s share of net loss and total comprehensive loss for the year $ (90,478 ) $ (184,366 ) $ (6,220 )

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
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Property, Plant and Equipment	14. PROPERTY, PLANT AND EQUIPMENT The carrying amounts of each class of property, plant and equipment were as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Land $ 3,365,013 $ 3,258,518 $ 109,937 Buildings and improvements 58,028,631 58,272,864 1,966,021 Machinery and equipment 72,700,762 66,185,198 2,232,969 Other equipment 2,089,581 1,588,113 53,580 Construction in progress and machinery in transit 7,696,254 5,863,713 197,831 $ 143,880,241 $ 135,168,406 $ 4,560,338 For the year ended December 31, 2015 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total NT$ NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2015 $ 3,348,018 $ 86,725,254 $ 233,669,627 $ 7,182,574 $ 5,862,217 $ 336,787,690 Additions 132,584 553,496 401,417 27,193,324 28,280,821 Disposals - (405,040 ) (8,041,933 ) (232,555 ) (20,711 ) (8,700,239 ) Reclassification - 8,579,472 18,054,712 389,783 (26,893,158 ) 130,809 Effect of foreign currency exchange differences 33,282 (584,338 ) (952,295 ) (18,811 ) 256,088 (1,266,074 ) Balance at December 31, 2015 $ 3,381,300 $ 94,447,932 $ 243,283,607 $ 7,722,408 $ 6,397,760 $ 355,233,007 Accumulated depreciation and impairment Balance at January 1, 2015 $ - $ 30,329,544 $ 149,497,980 $ 5,365,887 $ 7,164 $ 185,200,575 Depreciation expense - 4,790,646 23,372,408 775,716 - 28,938,770 Impairment losses recognized - 120,424 31,116 - 106,589 258,129 Disposals - (308,895 ) (7,838,937 ) (224,509 ) - (8,372,341 ) Reclassification - 5,704 (11,920 ) 3,008 - (3,208 ) Effect of foreign currency exchange differences - (290,545 ) (482,349 ) (12,688 ) (411 ) (785,993 ) Balance at December 31, 2015 $ - $ 34,646,878 $ 164,568,298 $ 5,907,414 $ 113,342 $ 205,235,932 For the year ended December 31, 2016 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total NT$ NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2016 $ 3,381,300 $ 94,447,932 $ 243,283,607 $ 7,722,408 $ 6,397,760 $ 355,233,007 Additions - 22,341 94,480 470,901 27,093,140 27,680,862 Disposals - (684,698 ) (5,956,179 ) (159,822 ) (268,782 ) (7,069,481 ) Reclassification - 5,110,102 19,661,732 691,276 (25,463,285 ) (175 ) Acquisitions through business combinations - - - 1,159 - 1,159 Effect of foreign currency exchange differences (16,287 ) (2,637,502 ) (8,882,884 ) (251,261 ) (45,291 ) (11,833,225 ) Balance at December 31, 2016 $ 3,365,013 $ 96,258,175 $ 248,200,756 $ 8,474,661 $ 7,713,542 $ 364,012,147 Accumulated depreciation and impairment Balance at January 1, 2016 $ - $ 34,646,878 $ 164,568,298 $ 5,907,414 $ 113,342 $ 205,235,932 Depreciation expense - 5,114,263 22,983,290 864,061 - 28,961,614 Impairment losses recognized - 620 876,123 5,564 5,924 888,231 Disposals - (449,198 ) (5,544,489 ) (151,875 ) (100,049 ) (6,245,611 ) Reclassification - (5,123 ) 9,660 (4,537 ) - - Acquisitions through business combinations - - - 824 - 824 Effect of foreign currency exchange differences - (1,077,896 ) (7,392,888 ) (236,371 ) (1,929 ) (8,709,084 ) Balance at December 31, 2016 $ - $ 38,229,544 $ 175,499,994 $ 6,385,080 $ 17,288 $ 220,131,906 For the year ended December 31, 2017 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total NT$ NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2017 $ 3,365,013 $ 96,258,175 $ 248,200,756 $ 8,474,661 $ 7,713,542 $ 364,012,147 Additions - 350,434 102,301 130,659 23,094,288 23,677,682 Disposals - (609,294 ) (8,449,949 ) (763,937 ) (73,248 ) (9,896,428 ) Reclassification (35,965 ) 6,483,392 18,331,738 174,947 (25,428,464 ) (474,352 ) Effect of foreign currency exchange differences (70,530 ) (2,294,779 ) (4,986,843 ) (204,250 ) 557,595 (6,998,807 ) Balance at December 31, 2017 $ 3,258,518 $ 100,187,928 $ 253,198,003 $ 7,812,080 $ 5,863,713 $ 370,320,242 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ 38,229,544 $ 175,499,994 $ 6,385,080 $ 17,288 $ 220,131,906 Depreciation expense - 5,156,558 22,722,307 746,422 - 28,625,287 Impairment losses recognized - 2,310 286,880 368 - 289,558 Disposals - (478,903 ) (7,540,654 ) (720,319 ) (17,288 ) (8,757,164 ) Reclassification - (210,080 ) 34,452 (24,117 ) - (199,745 ) Effect of foreign currency exchange differences - (784,365 ) (3,990,174 ) (163,467 ) - (4,938,006 ) Balance at December 31, 2017 $ - $ 41,915,064 $ 187,012,805 $ 6,223,967 $ - $ 235,151,836 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Cost Balance at January 1,2017 $ 113,529 $ 3,247,577 $ 8,373,845 $ 285,920 $ 260,241 $ 12,281,112 Additions - 11,823 3,451 4,408 779,160 798,842 Disposals - (20,556 ) (285,086 ) (25,774 ) (2,471 ) (333,887 ) Reclassification (1,212 ) 218,738 618,480 5,902 (857,911 ) (16,003 ) Effect of foreign currency exchange differences (2,380 ) (77,422 ) (168,247 ) (6,891 ) 18,812 (236,128 ) Balance at December 31, 2017 $ 109,937 $ 3,380,160 $ 8,542,443 $ 263,565 $ 197,831 $ 12,493,936 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ 1,289,796 $ 5,921,052 $ 215,421 $ 583 $ 7,426,852 Depreciation expense - 173,973 766,610 25,183 - 965,766 Impairment losses recognized - 78 9,679 12 - 9,769 Disposals - (16,157 ) (254,408 ) (24,302 ) (583 ) (295,450 ) Reclassification - (7,088 ) 1,162 (814 ) - (6,740 ) Effect of foreign currency exchange differences - (26,463 ) (134,621 ) (5,515 ) - (166,599 ) Balance at December 31,2017 $ - $ 1,414,139 $ 6,309,474 $ 209,985 $ - $ 7,933,598 Due to the Group’s future operation plans and capacity evaluation or production demands in segment of packaging and testing, the Group believed that a portion of property, plant and equipment does not qualify for the production needs and therefore recognized an impairment loss of NT$258,129 thousand, NT$888,231 thousand and NT$289,558 thousand (US$9,769 thousand) under the line item of other operating income and expenses in the consolidated statements of comprehensive income for the years ended December 31, 2015, 2016 and 2017, respectively. The recoverable amount of the impaired property, plant and equipment is determined on the basis of its value in use and the Group expects to derive zero future cash flows from these assets. Each class of property, plant and equipment was depreciated on a straight-line basis over the following useful lives: Buildings and improvements Main plant buildings 10-40 years Cleanrooms 10-20 years Others 3-20 years Machinery and equipment 2-10 years Other equipment 2-20 years The capitalized borrowing costs for the years ended December 31, 2015, 2016 and 2017 are disclosed in Note 24

Investment Properties

Investment Properties	12 Months Ended
	Dec. 31, 2017
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Investment Properties	15. INVESTMENT PROPERTIES Land Buildings and improvements Total NT$ NT$ NT$ Cost Balance at January 1, 2017 $ - $ - $ - Additions - 186,535 186,535 Disposals - (342 ) (342 ) Transfers from inventories related to real estate business and property, plant and equipment 35,965 8,114,110 8,150,075 Effects of foreign currency exchange differences - 106,482 106,482 Balance at December 31, 2017 $ 35,965 $ 8,406,785 $ 8,442,750 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ - $ - Depreciation expenses - 122,231 122,231 Disposals - (161 ) (161 ) Transfers from property, plant and equipment - 199,745 199,745 Effects of foreign currency exchange differences - 1,499 1,499 Balance at December 31, 2017 $ - $ 323,314 $ 323,314 Land Buildings and improvements Total US$ (Note 4) US$ (Note 4) US$ (Note 4) Cost Balance at January 1, 2017 $ - $ - $ - Additions - 6,293 6,293 Disposals - (11 ) (11 ) Transfers from inventories related to real estate business and property, plant and equipment 1,213 273,755 274,968 Effects of foreign currency exchange differences - 3,593 3,593 Balance at December 31, 2017 $ 1,213 $ 283,630 $ 284,843 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ - $ - Depreciation expenses - 4,124 4,124 Disposals - (5 ) (5 ) Transfers from property, plant and equipment - 6,739 6,739 Effects of foreign currency exchange differences - 50 50 Balance at December 31, 2017 $ - $ 10,908 $ 10,908 The investment properties are depreciated using the straight-line method over their estimated useful lives as follows: Main buildings 10-40 years Others 3-20 years The fair value of the investment properties was approximately NT$11,560,440 thousand (US$390,028 thousand) which was measured using the market approach and the income approach based on level 3 inputs by independent professional appraisers. Investment properties are held under freehold interests. Refer to Note 36 for the carrying amount of the investment properties that had been pledged by the Group to secure borrowings.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2017
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Goodwill	16. GOODWILL Cost Accumulated impairment Carrying amount NT$ NT$ NT$ Balance at January 1, 2015 $ 12,434,411 $ 1,988,996 $ 10,445,415 Effect of foreign currency exchange differences 61,104 - 61,104 Balance at December 31, 2015 12,495,515 1,988,996 10,506,519 Acquisitions through business combinations (retrospectively adjusted) (Note 28) 15,323 - 15,323 Effect of foreign currency exchange differences (31,533 ) - (31,533 ) Balance at December 31, 2016 (retrospectively adjusted) 12,479,305 1,988,996 10,490,309 Impairment losses recognized - 425,117 (425,117 ) Effect of foreign currency exchange differences (130,698 ) - (130,698 ) Balance at December 31, 2017 $ 12,348,607 $ 2,414,113 $ 9,934,494 Cost Accumulated impairment Carrying amount US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1, 2017 (retrospectively adjusted) (Note 28) $ 421,029 $ 67,105 $ 353,924 Impairment losses recognized - 14,343 (14,343 ) Effect of foreign currency exchange differences (4,409 ) - (4,409 ) Balance at December 31, 2017 $ 416,620 $ 81,448 $ 335,172 a. Allocating goodwill to cash-generating units Goodwill had been allocated to the following cash-generating units for impairment testing purposes: packaging segment, testing segment, EMS segment and other segment. The carrying amount of goodwill allocated to cash-generating units was as follows: December 31 2016 (Retrospectively Adjusted) 2017 Cash-generating units NT$ NT$ US$ (Note 4) Testing segment $ 7,868,961 $ 7,775,581 $ 262,334 Others 2,621,348 2,158,913 72,838 $ 10,490,309 $ 9,934,494 $ 335,172 b. Impairment assessment At the end of each year, the Group performs impairment assessment by reviewing the recoverable amounts based on value in use which incorporates cash flow projections covering a five-year period. The cash flows beyond that five-year period have been extrapolated using a steady 2.0% per annum growth rate. In assessing value in use, the estimated future cash flows are discounted to their present value using annual discount rates. The Group carried out a review that the recoverable amount of other segment was lower than its carrying amount since its actual growth in revenue did not meet its forecast previously made by management. The review led to the recognition of an impairment loss of NT$425,117 thousand (US$14,343 thousand) under the line item of other gains, net in the consolidated statements of comprehensive income for the year ended December 31, 2017. The key assumptions used in the value in use calculations are growth rates for operating revenue and discount rates. Growth rates for operating revenue are based on the revenue forecast for the Group and the market as well as the Group’s historical experience. The discount rates were 8.67%- 10.71%, 9.09%- 10.49% and 8.97%- 11.29% as of December 31, 2015, 2016 and 2017, respectively. Management believed that any reasonably possible change in the key assumptions on which recoverable amount was based would not cause the aggregate carrying amount of the cash-generating unit to exceed its aggregate recoverable amount significantly.

Other Intangible Assets

Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
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Other Intangible Assets	17. OTHER INTANGIBLE ASSETS The carrying amounts of each class of other intangible assets were as follows: December 31 2016 (Retrospectively Adjusted) 2017 NT$ NT$ US$ (Note 4) Customer relationships $ 194,089 $ 113,776 $ 3,839 Computer software 943,527 864,331 29,161 Patents and acquired specific technology 359,227 319,402 10,776 Others 120,418 109,356 3,689 $ 1,617,261 $ 1,406,865 $ 47,465 For the year ended December 31, 2015 Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2015 $ 1,579,015 $ 2,882,932 $ 2,139,138 $ 184,409 $ 6,785,494 Additions - 481,412 209 9,514 491,135 Disposals or derecognization (663,379 ) (8,426 ) (1,983,914 ) (204 ) (2,655,923 ) Reclassification - 12,360 - - 12,360 Effect of foreign currency exchange differences - (29,918 ) (1,351 ) (381 ) (31,650 ) Balance at December 31, 2015 $ 915,636 $ 3,338,360 $ 154,082 $ 193,338 $ 4,601,416 Accumulated amortization Balance at January 1, 2015 $ 1,077,514 $ 2,084,805 $ 2,118,254 $ 37,050 $ 5,317,623 Amortization expense 227,099 325,856 9,461 17,478 579,894 Disposals or derecognization (663,379 ) (7,402 ) (1,983,914 ) - (2,654,695 ) Reclassification - 3,190 - - 3,190 Effect of foreign currency exchange differences - (21,411 ) (5,415 ) 137 (26,689 ) Balance at December 31, 2015 $ 641,234 $ 2,385,038 $ 138,386 $ 54,665 $ 3,219,323 For the year ended December 31, 2016 (Retrospectively Adjusted) Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2016 $ 915,636 $ 3,338,360 $ 154,082 $ 193,338 $ 4,601,416 Additions (Note 35) - 372,188 301,351 1,605 675,144 Disposals or derecognization (41,099 ) (80,537 ) (1,310 ) - (122,946 ) Reclassification - - 786 - 786 Acquisitions through business combinations 41,099 - 64,380 30 105,509 Effect of foreign currency exchange differences - (77,782 ) (4,846 ) (2,581 ) (85,209 ) Balance at December 31, 2016 $ 915,636 $ 3,552,229 $ 514,443 $ 192,392 $ 5,174,700 (continued) Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Accumulated amortization Balance at January 1, 2016 $ 641,234 $ 2,385,038 $ 138,386 $ 54,665 $ 3,219,323 Amortization expense 121,412 345,836 24,154 17,421 508,823 Disposals or derecognization (41,099 ) (58,765 ) (1,310 ) - (101,174 ) Reclassification - - 786 - 786 Acquisitions through business combinations - - 483 23 506 Effect of foreign currency exchange differences - (63,407 ) (7,283 ) (135 ) (70,825 ) Balance at December 31, 2016 $ 721,547 $ 2,608,702 $ 155,216 $ 71,974 $ 3,557,439 (concluded) For the year ended December 31, 2017 Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2017 (retrospectively adjusted) $ 915,636 $ 3,552,229 $ 514,443 $ 192,392 $ 5,174,700 Additions - 265,497 - 12,328 277,825 Disposals - (83,595 ) (123,744 ) (4,978 ) (212,317 ) Effect of foreign currency exchange differences - (47,679 ) (1,213 ) (988 ) (49,880 ) Balance at December 31, 2017 $ 915,636 $ 3,686,452 $ 389,486 $ 198,754 $ 5,190,328 Accumulated amortization Balance at January 1, 2017 (retrospectively adjusted) $ 721,547 $ 2,608,702 $ 155,216 $ 71,974 $ 3,557,439 Amortization expense 80,313 316,580 43,493 17,280 457,666 Disposals - (72,481 ) (123,743 ) - (196,224 ) Effect of foreign currency exchange differences - (30,680 ) (4,882 ) 144 (35,418 ) Balance at December 31, 2017 $ 801,860 $ 2,822,121 $ 70,084 $ 89,398 $ 3,783,463 Customer relationships Computer software Patents and acquired specific technology Others Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Cost Balance at January 1, 2017 (retrospectively adjusted) $ 30,892 $ 119,846 $ 17,356 $ 6,491 $ 174,585 Additions - 8,957 - 416 9,373 Disposals - (2,820 ) (4,175 ) (168 ) (7,163 ) Effect of foreign currency exchange differences - (1,609 ) (41 ) (34 ) (1,684 ) Balance at December 31, 2017 $ 30,892 $ 124,374 $ 13,140 $ 6,705 $ 175,111 Accumulated amortization Balance at January 1, 2017 (retrospectively adjusted) $ 24,343 $ 88,012 $ 5,237 $ 2,428 $ 120,020 Amortization expense 2,710 10,681 1,467 583 15,441 Disposals - (2,445 ) (4,175 ) - (6,620 ) Effect of foreign currency exchange differences - (1,035 ) (165 ) 5 (1,195 ) Balance at December 31, 2017 $ 27,053 $ 95,213 $ 2,364 $ 3,016 $ 127,646 Each class of other intangible assets were amortized on the straight-line basis over the following useful lives: Customer relationships 11 years Computer software 2-10 years Patents and acquired specific technology 5-15 years Others 5-32 years

Long-term Prepayments for Lease

Long-term Prepayments for Lease	12 Months Ended
	Dec. 31, 2017
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Long-term Prepayments for Lease	18. LONG-TERM PREPAYMENTS FOR LEASE Long-term prepayments for lease mainly represented land use rights located in China with periods for use from 40 to 70 years and will expire from 2049 to 2074, respectively.

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2017
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Borrowings	19. BORROWINGS a. Short-term borrowings Short-term borrowings mainly represented unsecured revolving bank loans with annual interest rates at 0.70%-8.99% and 0.80%-4.79% as of December 31, 2016 and 2017, respectively. b. Long-term borrowings 1) Bank loans As of December 31, 2016 and 2017, the long-term bank loans with fixed interest rates were both amounted to NT$1,500,000 thousand (US$50,607 thousand) with annual interest rates at 1.20%. The long-term bank loans with fixed interest rates will be repayable in December 2018. The others were long-term bank loans with floating interest rates and consisted of the followings: December 31 2016 2017 NT$ NT$ US$ (Note 4) Working capital bank loans Syndicated bank loans - repayable through January 2018 to July 2018, annual interest rates were 2.55% and 2.61% -2.70% as of December 31, 2016 and 2017, respectively $ 9,223,500 $ 4,761,600 $ 160,647 Others - repayable through January 2018 to December 2019, annual interest rates were 0.74%-4.48% and 0.93%-2.10% as of December 31, 2016 and 2017, respectively 36,009,917 22,441,947 757,151 Mortgage loans Repayable through July 2018 to June 2023, annual interest rates were both 4.95%-5.39% as of December 31, 2016 and 2017 4,390,003 4,705,149 158,743 49,623,420 31,908,696 1,076,541 Less: unamortized arrangement fee 7,198 1,200 40 49,616,222 31,907,496 1,076,501 Less: current portion 6,567,565 6,761,625 228,125 $ 43,048,657 $ 25,145,871 $ 848,376 Pursuant to the above syndicated bank loans agreements, the Company should maintain certain financial covenants including current ratio, leverage ratio, tangible net assets and interest coverage ratio. Such financial ratios are calculated based on the Group’s annual audited consolidated financial statements or semi-annual reviewed consolidated financial statements. The Company was in compliance with all of the financial covenants as of December 31, 2016 and 2017. 2) Long-term bills payable December 31 2016 2017 NT$ NT$ US$ (Note 4) China Bills Finance Corporation, repayable in February 2019, annual interest rate was 0.96% $ - $ 1,000,000 $ 33,738 International Bills Finance Corporation, repayable in March 2019, annual interest rate was 0.96% - 1,000,000 33,738 Ta Ching Bills Finance Corporation, annual interest rates was 1.00% and has been repaid in December 2017 2,000,000 - - 2,000,000 2,000,000 67,476 Less: unamortized discounts 659 868 29 Long-term borrowings $ 1,999,341 $ 1,999,132 $ 67,447

Bonds Payable

Bonds Payable	12 Months Ended
	Dec. 31, 2017
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Bonds Payable	20. BONDS PAYABLE December 31 2016 2017 NT$ NT$ US$ (Note 4) Unsecured domestic bonds Repayable at maturity in January 2021 and interest due annually with annual interest rate at 1.30% $ 7,000,000 $ 7,000,000 $ 236,168 Repayable at maturity in January 2023 and interest due annually with annual interest rate at 1.50% 2,000,000 2,000,000 67,476 Repayable at maturity in January 2022 and interest due annually with annual interest rate at 1.25% - 3,700,000 124,831 Repayable at maturity in January 2024 and interest due annually with annual interest rate at 1.45% - 4,300,000 145,074 Unsecured convertible overseas bonds US$400,000 thousand 12,900,000 - - US$200,000 thousand (linked to New Taiwan dollar) 6,185,600 6,185,600 208,691 Secured overseas bonds - secured by the Company US$300,000 thousand, interest due semi-annually with annual interest rate at 2.125% and has been repaid in July 2017 9,675,000 - - 37,760,600 23,185,600 782,240 Less: discounts on bonds payable 760,697 42,820 1,444 36,999,903 23,142,780 780,796 Less: current portion 9,658,346 6,161,197 207,868 $ 27,341,557 $ 16,981,583 $ 572,928 a. In September 2013, the Company offered the third unsecured convertible overseas bonds (the “Bonds”) in US$400,000 thousand. The Bonds is zero coupon bonds with the maturity of 5 years, in denominations of US$200 thousand or in any integral multiples thereof. Each holder of the Bonds has the right at any time on or after October 16, 2013 and up to (and including) August 26, 2018, except during legal lock-up period, to convert the Bonds into newly issued listed common shares at the conversion price NT$33.085, determined on the basis of a fixed exchange rate of US$1 to NT$29.956. The conversion price will be adjusted in accordance with the conversion provisions due to anti-dilution clause. As of December 31, 2016, the conversion price was NT$28.99. As of December 31, 2017, the Bonds holders have exercised the conversion right to convert the Bonds of US$399,600 thousand into the company’s ordinary shares at conversion prices from NT$27.95 (US$0.94) to NT$28.96 (US$0.98). The Bonds may be redeemed at the option of the Company, in whole or in part, at any time on or after the third anniversary of the offering date provided that (1) the closing price, translated into U.S. dollars, of the common shares for a period of 20 consecutive trading days is at least 130% of the conversion price, (2) at least 90% in aggregate principal amount of the Bonds originally outstanding has been redeemed, repurchased and canceled or converted, or (3) the Company is required to pay additional taxes on the Bonds as a result of certain changes in tax laws in the ROC. Each holder shall have the right to request the Company repurchase all or any portion of the principal amount thereof of a holder’s Bonds (1) on the third anniversary of the offering date, (2) in the event of a change of control, or (3) in the event of delisting. The Bonds contained a debt host contract, recognized as bonds payable, and the conversion option, redemption option and put option (collectively the “Bonds Options”) aggregately recognized as financial liabilities at FVTPL. The effective interest rate of the debt host contract was 3.16% and the aggregate fair value of the Bonds Options was NT$1,667,950 thousand on initial recognition. The Company’s board of directors resolved in third quarter of 2017 to issue a notice of early redemption to Bonds holders. In the third quarter of 2017, the closing price of the Company’s ordinary shares (translated into U.S. dollars at the prevailing rates) for a period of 20 consecutive trading days is higher than 130% of the conversion price in U.S. dollar translated at the fixed exchange rate of US$1 to NT$29.956 determined on pricing date per ordinary share. Therefore, except those have been converted, the Company early redeemed the outstanding Bonds of US$400 thousand in September 2017. b. In July 2015, the Company offered the forth unsecured convertible overseas bonds (the “Currency Linked Bonds”) in US$200,000 thousand. The Currency Linked Bonds is zero coupon bonds with the maturity of 2.75 years, in denominations of US$200 thousand or in any integral multiples thereof. Repayment, redemption and put amount denominated in U.S. dollar will be converted into New Taiwan dollar amount using a fixed exchange rate of US$1 to NT$30.928 (the “Fixed Exchange Rate”) and then converted back to U.S. dollar amount using the applicable prevailing rate at the time of repayment, redemption or put. Each holder of the Currency Linked Bonds has the right at any time on or after August 11, 2015 and up to (and including) March 17, 2018, except during legal lock-up period, to convert the Currency Linked Bonds into common shares at the conversion price NT$54.55, determined on the basis of the Fixed Exchange Rate. The Company’s treasury shares will be available for delivery upon conversion of the Currency Linked Bonds. The conversion price will be adjusted in accordance with the conversion provisions due to anti-dilution clause. As of December 31, 2016 and 2017, the conversion price was NT$49.52 and NT$47.76 (US$1.61), respectively. The Currency Linked Bonds may be redeemed at the option of the Company, in whole or in part, at any time on or after March 19, 2018 provided that (1) the closing price, translated into U.S. dollars, of the common shares for a period of 20 out of 30 consecutive trading days is at least 130% of the conversion price, (2) at least 90% in aggregate principal amount of the Currency Linked Bonds originally outstanding has been redeemed, repurchased and canceled or converted, or (3) the Company is required to pay additional taxes on the Currency Linked Bonds as a result of certain changes in tax laws in the ROC. Each holder shall have the right to request the Company repurchase all or any portion of the principal amount thereof of a holder’s Currency Linked Bonds (1) in the event of a change of control, or (2) in the event of delisting. The Currency Linked Bonds contained a debt host contract, recognized as bonds payable, and the conversion option, recognized as capital surplus. The effective interest rate of the debt host contract was 1.58% and the fair value of the conversion option was NT$214,022 thousand on initial recognition. c. To focus on corporate sustainability and to carry out the commitment to environmental protection and energy conservation, Anstock II Limited, a subsidiary the Company 100% owned, offered overseas bonds in US$300,000 thousand with the maturity of 3 years and annual interest rate of 2.125% (the “Green Bonds”) in July 2014. The Green Bonds are unconditionally and irrevocably guaranteed by the Company and the proceeds were used to fund certain eligible projects to promote the Group’s transition to low-carbon and climate resilient growth. As of December 31, 2017, the Company’s subsidiary has repaid the Green Bonds.

Other Payables

Other Payables	12 Months Ended
	Dec. 31, 2017
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Other Payables	21. OTHER PAYABLES December 31 2016 2017 NT$ NT$ US$ (Note 4) Accrued salary and bonus $ 6,606,406 $ 7,292,254 $ 246,027 Payables for property, plant and equipment 5,605,528 4,623,268 155,981 Accrued employees’ compensation and remuneration to directors 2,400,778 2,568,880 86,669 Accrued employee insurance 617,419 657,176 22,172 Accrued utilities 410,796 417,257 14,077 Payables for patents and acquired specific technology (Note 35) 120,938 93,000 3,138 Others 5,760,169 5,726,052 193,187 $ 21,522,034 $ 21,377,887 $ 721,251

Retirement Benefit Plans

Retirement Benefit Plans	12 Months Ended
	Dec. 31, 2017
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Retirement Benefit Plans	22. RETIREMENT BENEFIT PLANS a. Defined contribution plans 1) The pension plan under the ROC Labor Pension Act (“LPA”) for the Group’s ROC resident employees is a government-managed defined contribution plan. Based on the LPA, the Company and its subsidiaries in Taiwan makes monthly contributions to employees’ individual pension accounts at 6% of their monthly salaries. 2) The subsidiaries located in China, U.S.A., Malaysia, Singapore and Mexico also make contributions at various ranges according to relevant local regulations. b. Defined benefit plans 1) The Company and its subsidiaries in Taiwan joined the defined benefit pension plan under the ROC Labor Standards Law operated by the government. Pension benefits are calculated on the basis of the length of service and average monthly salaries of the last six months before retirement. The Company and its subsidiaries in Taiwan make contributions based on a certain percentage of their domestic employees’ monthly salaries to a pension fund administered by the pension fund monitoring committee. Before the end of each year, the Company and its subsidiaries in Taiwan assess the balance in the pension fund. If the amount of the balance in the pension fund is inadequate to pay retirement benefits for employees who conform to retirement requirements in the next year, the Company and its subsidiaries in Taiwan are required to fund the difference in one appropriation that should be made before the end of March of the next year. Pension contributions are deposited in the Bank of Taiwan in the committee’s name and are managed by the Bureau of Labor Funds, Ministry of Labor (“the Bureau”); the Company and its subsidiaries in Taiwan have no right to influence the investment policy and strategy. 2) ASE Japan has a pension plan under which eligible employees with more than ten years of service are entitled to receive pension benefits based on their length of service and salaries at the time of termination of employment. ASE Japan makes contributions based on a certain amount of pension cost to employees. ASE Korea also has a pension plan under which eligible employees and directors with more than one year of service are entitled to receive a lump-sum payment upon termination of their service with ASE Korea, based on their length of service and salaries at the time of termination. ASE Korea makes contributions based on a certain percentage of pension cost to an external financial institution administered by the management and in the names of employees. 3) ASE Inc., ASE Test, Inc. and ASE Electronics Inc. maintain pension plans for executive managers. Pension costs under the plans were NT$2,302 thousand, NT$6,872 thousand and NT$3,171 thousand (US$107 thousand) for the years ended December 31, 2015, 2016 and 2017, respectively. Pension payments were NT$2,549 thousand for the year ended December 31, 2015 and were both nil for the years ended December 31, 2016 and 2017. As of December 31, 2016 and 2017, accrued pension liabilities for executive managers were NT$206,467 thousand and NT$209,637 thousand (US$7,073 thousand), respectively. 4) The amounts included in the consolidated balance sheets arising from the Group’s obligation in respect of its defined benefit plans excluding those for executive managers were as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Present value of the defined benefit obligation $ 8,389,884 $ 7,910,638 $ 266,891 Fair value of plan assets (4,417,367 ) (4,341,373 ) (146,470 ) Present value of unfunded defined benefit obligation 3,972,517 3,569,265 120,421 Recorded under other payables (22,273 ) (24,638 ) (831 ) Recorded under other current assets 15,542 182,421 6,154 Net defined benefit liability $ 3,965,786 $ 3,727,048 $ 125,744 Movements in net defined benefit liability (asset) were as follows: Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) NT$ NT$ NT$ Balance at January 1, 2015 $ 7,674,293 $ (3,502,487 ) $ 4,171,806 Service cost Current service cost 335,655 - $ 335,655 Net interest expense (income) 183,889 (108,356 ) 75,533 Recognized in profit or loss 519,544 (108,356 ) 411,188 Remeasurement Return on plan assets (excluding amounts included in net interest) - 12,426 12,426 Actuarial loss arising from changes in financial assumptions 309,695 - 309,695 Actuarial gain arising from experience adjustments (243,363 ) - (243,363 ) Actuarial gain arising from changes in demographic assumptions (15,847 ) - (15,847 ) Recognized in other comprehensive income 50,485 12,426 62,911 Contributions from the employer - (611,581 ) (611,581 ) Benefits paid from the pension fund (192,928 ) 192,928 - Benefits paid from the Group (43,088 ) - (43,088 ) Exchange differences on foreign plans (34,630 ) 43,341 8,711 Balance at December 31, 2015 7,973,676 (3,973,729 ) 3,999,947 Service cost Current service cost 329,838 - 329,838 Net interest expense (income) 167,111 (109,080 ) 58,031 Recognized in profit or loss 496,949 (109,080 ) 387,869 Remeasurement Return on plan assets (excluding amounts included in net interest) - 54,549 54,549 Actuarial loss arising from changes in financial assumptions 156,193 - 156,193 Actuarial loss arising from experience adjustments 200,723 - 200,723 Actuarial loss arising from changes in demographic assumptions 5,716 - 5,716 Recognized in other comprehensive income 362,632 54,549 417,181 Contributions from the employer - (807,232 ) (807,232 ) Benefits paid from the pension fund (308,471 ) 308,471 - Benefits paid from the Group (36,033 ) - (36,033 ) (Continued) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) NT$ NT$ NT$ Liabilities assumed in a business combination $ 535 $ (535 ) $ - Exchange differences on foreign plans (99,404 ) 110,189 10,785 Balance at December 31, 2016 8,389,884 (4,417,367 ) 3,972,517 Service cost Current service cost 278,412 - 278,412 Past service cost and gain on settlements (68,979 ) - (68,979 ) Net interest expense (income) 157,404 (103,741 ) 53,663 Recognized in profit or loss 366,837 (103,741 ) 263,096 Remeasurement Return on plan assets (excluding amounts included in net interest) - 52,124 52,124 Actuarial loss arising from changes in financial assumptions 56,860 - 56,860 Actuarial gain arising from experience adjustments (315,090 ) - (315,090 ) (Continued) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) NT$ NT$ NT$ Actuarial loss arising from changes in demographic assumptions $ 762 $ - $ 762 Recognized in other comprehensive income (257,468 ) 52,124 (205,344 ) Contributions from the employer - (484,790 ) (484,790 ) Benefits paid from the pension fund (690,830 ) 690,830 - Benefits paid from the Group (96,575 ) - (96,575 ) Exchange differences on foreign plans 198,790 (78,429 ) 120,361 Balance at December 31, 2017 $ 7,910,638 $ (4,341,373 ) $ 3,569,265 (Concluded) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1, 2017 $ 283,060 $ (149,034 ) $ 134,026 Service cost Current service cost 9,393 - 9,393 Past service cost and gain on settlements (2,328 ) - (2,328 ) Net interest expense (income) 5,311 (3,500 ) 1,811 Recognized in profit or loss 12,376 (3,500 ) 8,876 (Continued) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) US$ (Note 4) US$ (Note 4) US$ (Note 4) Remeasurement Return on plan assets (excluding amounts included in net interest) $ - $ 1,759 $ 1,759 Actuarial loss arising from changes in financial assumptions 1,918 - 1,918 Actuarial gain arising from experience adjustments (10,631 ) - (10,631 ) Actuarial loss arising from changes in demographic assumptions 26 - 26 Recognized in other comprehensive income (8,687 ) 1,759 (6,928 ) Contributions from the employer - (16,356 ) (16,356 ) Benefits paid from the pension fund (23,307 ) 23,307 - Benefits paid from the Group (3,258 ) - (3,258 ) Exchange differences on foreign plans 6,707 (2,646 ) 4,061 Balance at December 31, 2017 $ 266,891 $ (146,470 ) $ 120,421 (concluded) 5) The fair value of the plan assets by major categories at each balance sheet date was as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Cash $ 2,232,367 $ 2,317,764 $ 78,197 Debt instruments 1,030,384 691,619 23,334 Equity instruments 1,071,777 1,254,109 42,311 Others 82,839 77,881 2,628 Total $ 4,417,367 $ 4,341,373 $ 146,470 6) Through the defined benefit plans under the Labor Standards Law, the Company and its subsidiaries in Taiwan are exposed to the following risks: a) Investment risk The plan assets are invested in equity and debt securities, bank deposits, etc. The investment is conducted at the discretion of the Bureau or under the mandated management. However, in accordance with relevant regulations, the return generated by plan assets should not be below the interest rate for a 2-year time deposit with local banks. b) Interest risk A decrease in the government bond interest rate will increase the present value of the defined benefit obligation; however, this will be partially offset by an increase in the return on the plan’s debt investments. c) Salary risk The present value of the defined benefit obligation is calculated by reference to the future salaries of plan participants. As such, an increase in the salary of the plan participants will increase the present value of the defined benefit obligation. 7) The management of ASE Korea is responsible for the administration of the fund and determination of the investment strategies according to related local regulations. ASE Korea is responsible for the shortfall between the fund and the defined benefit obligation. The plan assets are invested in the certificates of deposits and debt instruments with well credit rating. 8) The present value of the defined benefit obligation and the related current service cost and past service cost were measured using the Projected Unit Credit Method. Except the pension plans for executive managers, the key assumptions used for the actuarial valuations were as follow: December 31 2016 2017 Discount rates 0.06%-3.58% 0.06%-3.85% Expected rates of salary increase 2.00%-4.42% 2.00%-4.42% Significant actuarial assumptions for the determination of the defined obligation excluding those for executive managers are discount rates and expected rates of salary increase. The sensitivity analysis below has been determined based on reasonably possible changes of the respective assumptions occurring at each balance sheet date, while holding all other assumptions constant. December 31 2016 2017 NT$ NT$ US$ (Note 4) Discount Rate 0.5% higher $ (464,647 ) $ (455,158 ) $ (15,356 ) 0.5% lower $ 508,862 $ 461,891 $ 15,583 Expected rates of salary increase 0.5% higher $ 500,051 $ 453,792 $ 15,310 0.5% lower $ (452,956 ) $ (444,493 ) $ (14,996 ) The sensitivity analysis presented above may not be representative of the actual change in the defined benefit obligation as it is unlikely that the change in assumptions would occur in isolation of one another as some of the assumptions may be correlated. 9) Maturity analysis of undiscounted pension benefit December 31 2016 2017 NT$ NT$ US$ (Note 4) No later than 1 year $ 292,100 $ 291,152 $ 9,823 Later than 1 year and not later than 5 years 1,673,549 1,551,496 52,345 Later than 5 years 17,129,585 16,507,747 556,941 $ 19,095,234 $ 18,350,395 $ 619,109 The Group expected to make contributions of NT$521,324 thousand and NT$272,911 thousand (US$9,208 thousand) to the defined benefit plans in the next year starting from January 1, 2017 and 2018, respectively. As of December 31, 2016 and 2017, the average duration of the defined benefit obligation excluding those for executive managers of the Group was 8 to 15 years and 8 to 14 years, respectively.

Equity

Equity	12 Months Ended
	Dec. 31, 2017
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Equity	23. EQUITY a. Share capital Ordinary shares December 31, 2016 December 31, 2017 Numbers of shares authorized (in thousands) 10,000,000 10,000,000 Numbers of shares reserved (in thousands) Employee share options 800,000 800,000 Number of shares issued and fully paid (in thousands) 7,946,184 8,738,079 December 31, 2016 December 31, 2017 NT$ NT$ US$ (Note 4) Share capital authorized $ 100,000,000 $ 100,000,000 $ 3,373,819 Share capital reserved Employee share options $ 8,000,000 $ 8,000,000 $ 269,906 Share capital issued $ 79,568,040 $ 87,380,787 $ 2,948,070 The holders of issued ordinary shares with a par value at $10 per share are entitled the right to vote and receive dividends, except the shares held by the Group’s subsidiaries which are not entitled the right to vote. As of December 31, 2016 and 2017, there were both 500,000 thousand ordinary shares included in the authorized shares that were not yet required to complete the share registration process. In December 2016, the board of directors approved the issuance of 300,000 thousand ordinary shares for cash capital increase at NT$34.3 per share. The aforementioned cash capital increase has been completed and the Company has completed the registration formalities in March 2017. As disclosed in Note 20, there were 424,258 thousand ordinary shares were issued under the conversion of Bonds in 2017. The record dates of 101,164 thousand and 323,094 thousand ordinary shares were July 13, 2017 and October 13, 2017, respectively. The Company has completed the registration formalities. American Depositary Receipts The Company issued ADSs and each ADS represents five ordinary shares. As of December 31, 2016 and 2017, 125,518 thousand and 115,261 thousand ADSs were outstanding and represented approximately 627,590 thousand and 576,305 thousand ordinary shares of the Company, respectively. b. Capital surplus December 31 2016 2017 NT$ NT$ US$ (Note 4) May be used to offset a deficit, distributed as cash dividends, or transferred to share capital (1) Arising from issuance of ordinary shares $ 5,844,397 $ 21,553,853 $ 727,188 Arising from conversion of bond payable - 1,930,066 65,117 Arising from the difference between consideration received and the carrying amount of the subsidiaries’ net assets during actual disposal or acquisition 7,176,958 7,176,958 242,137 May be used to offset a deficit only Arising from changes in percentage of ownership interest in subsidiaries (2) 6,134,228 6,084,895 205,293 Arising from treasury share transactions 950,368 1,151,345 38,844 Arising from exercised employee share options 630,411 1,089,178 36,747 Arising from expired employee share options (Note 27) 3,626 223,454 7,539 Arising from share of changes in capital surplus of associates 82,243 83,733 2,825 May not be used for any purpose Arising from employee share options 1,230,247 960,888 32,419 Arising from equity component of convertible bonds 214,022 214,022 7,221 Others (3) - 155,936 5,261 $ 22,266,500 $ 40,624,328 $ 1,370,591 1) Such capital surplus may be used to offset a deficit; in addition, when the Company has no deficit, such capital surplus may be distributed as cash dividends or transferred to share capital (limited to a certain percentage of the Company’s capital surplus and once a year). 2) Such capital surplus arises from the effect of changes in ownership interest in a subsidiary resulted from equity transactions other than actual disposal or acquisition, or from changes in capital surplus of subsidiaries accounted for using the equity method. 3) Such capital surplus arises from the excess of related carrying amount of related accounts over the par value and the Company has not completed registration formalities when the convertible bonds were converted into ordinary shares and employee share options were exercised. c. Retained earnings and dividend policy In accordance with the amendments to the Company Act in May 2015, the recipients of dividends and bonuses are limited to shareholders and do not include employees. The consequential amendments to the Company’s Articles of Incorporation was resolved at the Company’s annual shareholders’ meeting. For information about the accrual basis of the employees’ compensation and remuneration to directors and the actual appropriations, please refer to employee benefits expense under profit before income tax in Note 24(g). The amended Articles of Incorporation of ASE Inc. (the “Articles”) in June 2016 provides that annual net income shall be distributed in the following order: 1) Replenishment of deficits; 2) 10.0% as legal reserve; 3) Special reserve appropriated or reversed in accordance with laws or regulations set forth by the authorities concerned; 4) Addition or deduction of realized gains or losses on equity instruments at fair value through other comprehensive income; The Company is currently in the mature growth stage. To meet the capital needs for business development now and in the future and satisfy the shareholders’ demand for cash inflows, the Company shall use residual dividend policy to distribute dividends, of which the cash dividend is not lower than 30% of the total dividend distribution, with the remainder to be distributed in stock. A distribution plan is also to be made by the board of directors and passed for resolution in the shareholders’ meeting. Appropriation of earnings to legal reserve shall be made until the legal reserve equals the Company’s share capital. Legal reserve may be used to offset deficits. If the Company has no deficit and the legal reserve has exceeded 25% of the Company’s share capital, the excess may be transferred to capital or distributed in cash. Under Rule No. 1010012865 and Rule No. 1010047490 issued by the FSC and the directive titled “Questions and Answers for Special Reserves Appropriated Following Adoption of IFRSs”, the Company should appropriate to or reverse a special reserve. Expect for non-ROC resident shareholders, all shareholders receiving the dividends are allowed a tax credit equal to their proportionate share of the income tax paid by the Company. The appropriations of earnings for 2015 and 2016 resolved at the Company’s annual shareholders’ meetings in June 2016 and June 2017, respectively, were as follows: Appropriation of Earnings Dividends Per Share For Year 2015 For Year 2016 For Year 2015 For Year 2016 NT$ NT$ NT$ NT$ (in dollars) (in dollars) Legal reserve $ 1,947,887 $ 2,168,034 Cash dividends 12,476,779 11,415,198 $ 1.60 $ 1.40 $ 14,424,666 $ 13,583,232 d. Other equity 1) Exchange differences on translating foreign operations For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 4,540,862 $ 4,492,671 $ (1,643,623 ) $ (55,453 ) Exchange differences arising on translating foreign operations 11,459 (5,843,856 ) (4,952,815 ) (167,099 ) Share of exchange difference of associates and joint venture accounted for using the equity method (59,650 ) (292,438 ) (137,221 ) (4,630 ) Balance at December 31 $ 4,492,671 $ (1,643,623 ) $ (6,733,659 ) $ (227,182 ) 2) Unrealized gain (loss) on available-for-sale financial assets For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 526,778 $ 588,119 $ (197,314 ) $ (6,657 ) Unrealized gain (loss) arising on revaluation of available-for-sale financial assets (4,304 ) (257,240 ) 169,585 5,721 Cumulative loss reclassified to profit or loss on impairment of available-for-sale financial assets - - 50,206 1,694 Cumulative loss (gain) reclassified to profit or loss on disposal of available-for-sale financial assets 10,827 7,512 (1,517 ) (51 ) Share of unrealized gain (loss) on available-for-sale financial assets of associates and joint venture accounted for using the equity method 54,818 (535,705 ) 401,610 13,550 Balance at December 31 $ 588,119 $ (197,314 ) $ 422,570 $ 14,257 e. Treasury shares (in thousand shares) Balance at Balance at January 1 Addition Decrease December 31 2015 Shares held by subsidiaries 145,883 - - 145,883 Shares reserved for bonds conversion - 120,000 - 120,000 145,883 120,000 - 265,883 Balance at Balance at January 1 Addition Decrease December 31 2016 Shares held by subsidiaries 145,883 - - 145,883 Shares reserved for bonds conversion 120,000 - - 120,000 265,883 - - 265,883 2017 Shares held by subsidiaries 145,883 - - 145,883 Shares reserved for bonds conversion 120,000 - - 120,000 265,883 - - 265,883 In February 2015, the board of directors approved to repurchase up to 120,000 thousand of the Company’s ordinary shares which were reserved for equity conversion of convertible overseas bonds. The Company has completed the repurchase during March 2015 and the shares repurchased accounted for 1.53% of the Company’s total issued shares. The average repurchase price was NT$44.45 per share. The Company’s shares held by its subsidiaries at each balance sheet date were as follows: Shares Held By Subsidiaries Carrying amount Carrying amount Fair Value Fair Value (in thousand shares) NT$ US$ (Note 4) NT$ US$ (Note 4) December 31, 2016 ASE Test 88,200 $ 1,380,721 $ 2,915,026 J&R Holding 46,704 381,709 1,543,559 ASE Test, Inc. 10,979 196,677 362,849 145,883 $ 1,959,107 $ 4,821,434 December 31, 2017 ASE Test 88,200 $ 1,380,721 $ 46,583 $ 3,364,848 $ 113,524 J&R Holding 46,704 381,709 12,878 1,781,749 60,113 ASE Test, Inc. 10,979 196,677 6,636 418,840 14,131 145,883 $ 1,959,107 $ 66,097 $ 5,565,437 $ 187,768 Fair values of the Company’s shares held by subsidiaries are based on the closing price from an available published price quotation, which is a Level 1 input in terms of IFRS 13, at the balance sheet dates. The Company issued ordinary shares in connection with its merger with its subsidiaries. The shares held by its subsidiaries were reclassified from investments accounted for using the equity method to treasury shares on the proportion owned by the Company. Under the Securities and Exchange Act of the ROC, the Company shall neither pledge treasury shares nor exercise shareholders’ rights on these shares, such as rights to dividends and voting. The subsidiaries holding treasury shares, however, retain shareholders’ rights except the rights to participate in any share issuance for cash and voting. f. Non-controlling interests For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 8,209,860 $ 11,492,545 $ 12,000,551 $ 404,877 Attributable to Non-controlling interests: Share of profit for the year (Note 28) 968,567 1,253,438 1,677,941 56,611 Exchange difference on translating foreign operations (74,968 ) (601,787 ) (334,920 ) (11,300 ) Unrealized gain on available-for-sale financial assets 3,928 1,129 5,763 194 (Continued) For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Defined benefit plan actuarial gains (losses) $ (3,440 ) $ 8,846 $ (13,724 ) $ (463 ) Non-controlling interests arising from acquisition of subsidiaries (Note 28) - 42,857 - - Partial disposal of subsidiaries (Note 30) 1,712,836 26,436 (3,055 ) (103 ) Repurchase of outstanding ordinary shares of subsidiaries (Note 30) - (912,886 ) - - Spin-off of subsidiaries 3,006 - - - Non-controlling interest relating to outstanding vested employee share options held by the employees of subsidiaries 904,904 927,823 263,213 8,880 Non-controlling interest relating to outstanding expired employee share options - - (159,200 ) (5,371 ) Cash dividends to non-controlling interests (232,148 ) (237,850 ) (246,440 ) (8,314 ) Balance at December 31 $ 11,492,545 $ 12,000,551 $ 13,190,129 $ 445,011

Profit Before Income Tax

Profit Before Income Tax	12 Months Ended
	Dec. 31, 2017
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Profit Before Income Tax	24. PROFIT BEFORE INCOME TAX a. Other operating income and expenses, net For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Rental income $ 60,230 $ 51,607 $ 131,570 $ 4,439 Gain (loss) on disposal of property, plant and equipment and other assets (127,111 ) (127,159 ) 367,110 12,386 Impairment loss on property, plant and equipment and goodwill (258,129 ) (888,231 ) (714,675 ) (24,112 ) Loss on damages and claims (116,445 ) (12,778 ) (85,585 ) (2,888 ) Others 189,926 176,281 410,136 13,837 $ (251,529 ) $ (800,280 ) $ 108,556 $ 3,662 b. Other income For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Government subsidy $ 176,721 $ 332,758 $ 341,844 $ 11,533 Interest income 242,084 230,067 306,871 10,353 Dividends income 396,973 26,411 59,039 1,992 $ 815,778 $ 589,236 $ 707,754 $ 23,878 c. Other gains and losses For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Gain on disposal of subsidiaries (Note 29) $ - $ - $ 5,589,457 $ 188,578 Net gain (loss) arising on financial instruments held for trading 1,657,093 $ 224,446 (3,111,253 ) (104,968 ) Net gain on financial assets designated as at FVTPL 815,742 223,113 327,351 11,044 Foreign exchange gain or loss, net (713,213 ) 1,928,384 3,502,586 118,171 Impairment loss on financial assets - (91,886 ) (50,206 ) (1,694 ) Others (10,827 ) (7,513 ) 1,518 52 $ 1,748,795 $ 2,276,544 $ 6,259,453 $ 211,183 d. Finance costs For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Total interest expense for financial liabilities measured at amortized cost $ 2,514,208 $ 2,510,197 $ 2,016,298 $ 68,026 Less: Amounts included in the cost of qualifying assets Inventories related to real estate business (197,287 ) (238,469 ) (190,137 ) (6,415 ) Property, plant and equipment (48,135 ) (54,191 ) (51,262 ) (1,729 ) Investment property - - (13 ) - 2,268,786 2,217,537 1,774,886 59,882 Other finance costs 43,357 43,538 24,608 830 $ 2,312,143 $ 2,261,075 $ 1,799,494 $ 60,712 Information relating to the capitalized borrowing costs was as follows: For the Year Ended December 31 2015 2016 2017 Annual interest capitalization rates Inventories related to real estate business(%) 4.35-6.77 4.35-6.00 4.35-5.39 Property, plant and equipment(%) 0.75-6.15 1.15-4.42 1.26-5.49 Investment properties (%) - - 1.26-1.97 e. Depreciation and amortization For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Property, plant and equipment $ 28,938,770 $ 28,961,614 $ 28,625,287 $ 965,766 Investment properties - - 122,231 4,124 Intangible assets 579,894 508,823 457,666 15,441 Total $ 29,518,664 $ 29,470,437 $ 29,205,184 $ 985,331 Summary of depreciation by function Operating costs $ 27,023,957 $ 26,948,106 $ 26,731,714 $ 901,880 Operating expenses 1,914,813 2,013,508 2,015,804 68,010 $ 28,938,770 $ 28,961,614 $ 28,747,518 $ 969,890 (Continued) For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Summary of amortization by function Operating costs $ 124,235 $ 152,987 $ 140,175 $ 4,729 Operating expenses 455,659 355,836 317,491 10,712 $ 579,894 $ 508,823 $ 457,666 $ 15,441 (Concluded) f. Operating expenses directly related to investment properties For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Direct operating expenses of investment properties that generated rental income $ - $ - $ 465,458 $ 15,704 g. Employee benefits expense For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Post-employment benefits Defined contribution plans $ 2,324,737 $ 2,356,416 $ 2,340,826 $ 78,975 Defined benefit plans 413,490 394,741 266,267 8,983 2,738,227 2,751,157 2,607,093 87,958 Equity-settled share-based payments 133,496 470,788 438,765 14,803 Other employee benefits 47,883,464 49,525,940 51,043,198 1,722,105 $ 50,755,187 $ 52,747,885 $ 54,089,056 $ 1,824,866 Summary of employee benefits expense by function Operating costs $ 34,720,359 $ 35,588,529 $ 35,978,403 $ 1,213,846 Operating expenses 16,034,828 17,159,356 18,110,653 611,020 $ 50,755,187 $ 52,747,885 $ 54,089,056 $ 1,824,866 h. Employees’ compensation and the remuneration to directors To be in compliance with the Company Act as amended in May 2015, the amended Articles of Incorporation of the Company, which has been approved in the shareholders’ meeting in June 2016, stipulates to distribute employees’ compensation and remuneration to directors at the rates in 5.25%-8.25% and no higher than 0.75%, respectively, of net profit before income tax, employees’ compensation and remuneration to directors. For the years ended December 31, 2015, 2016 and 2017, the employees’ compensation and the remuneration to directors were accrued based on 8.25% and 0.75% of net profit before income tax, employees’ compensation and remuneration to directors, respectively, and were as follows. For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Employees’ compensation $ 2,033,500 $ 2,147,323 $ 2,291,140 $ 77,299 Remuneration to directors 184,500 195,211 208,285 7,027 If there is any change in the proposed amounts after the consolidated financial statements authorized for issue, the differences are recorded as a change in accounting estimate. The appropriations of employees’ compensation (settled by cash) and remuneration to directors for 2015 and 2016 resolved by the board of directors in April 2016 and in March 2017, respectively, and the amounts recognized in 2015 and 2016 consolidated financial statements were as follows. For Year 2015 For Year 2016 Employees’ compensation Remuneration to directors Employees’ compensation Remuneration to directors NT$ NT$ NT$ NT$ Resolved by the board of directors $ 2,033,800 $ 140,000 $ 2,151,900 $ 148,000 Recognized in the consolidated financial statements $ 2,033,500 $ 184,500 $ 2,147,323 $ 195,211 The differences between the resolved amounts of the employees’ compensation and the remuneration to directors and the accrued amounts reflected in the consolidated financial statements for the years ended December 31, 2015 and 2016 were deemed changes in estimates. The difference was NT$44,200 thousand and NT$42,634 thousand (US$1,438 thousand) and had been adjusted in net profit for the years ended December 31, 2016 and 2017, respectively.

Income Tax

Income Tax	12 Months Ended
	Dec. 31, 2017
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Income Tax	25. INCOME TAX a. Income tax recognized in profit or loss The major components of income tax were as follows: For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Current income tax In respect of the current year $ 4,029,076 $ 4,177,900 $ 4,979,766 $ 168,008 Income tax on unappropriated earnings 187,654 829,345 1,076,353 36,314 Changes in estimate for prior years (20,719 ) 28,160 (88,162 ) (2,974 ) 4,196,011 5,035,405 5,967,957 201,348 For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Deferred income tax In respect of the current year $ 190,829 $ 574,541 $ 534,472 $ 18,032 Adjustments attributable to changes in tax rates 3,794 14,184 - - Changes in estimate for prior years (20,890 ) (206,788 ) 52,872 1,784 Effect of foreign currency exchange differences (58,671 ) (26,498 ) (31,698 ) (1,070 ) 115,062 355,439 555,646 18,746 Income tax recognized in profit or loss $ 4,311,073 $ 5,390,844 $ 6,523,603 $ 220,094 A reconciliation of income tax expense calculated at the statutory rates and income tax expense recognized in profit or loss was as follows: For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Profit before income tax $ 25,011,788 $ 27,968,705 $ 31,020,663 $ 1,046,581 Income tax expense calculated at the statutory rates $ 6,307,148 $ 8,634,187 $ 10,890,498 $ 367,426 Nontaxable expense in determining taxable income 160,530 (34,954 ) 483,715 16,319 Tax-exempt income (537,987 ) (700,274 ) (623,566 ) (21,038 ) Additional income tax on unappropriated earnings 338,142 829,345 1,076,353 36,314 Loss carry-forward and income tax credits currently used (1,286,705 ) (898,700 ) (1,124,043 ) (37,923 ) Remeasurement of deferred income tax assets, net (688,584 ) (2,797,673 ) (4,131,473 ) (139,389 ) Changes in estimate for prior years (20,719 ) 28,160 (88,162 ) (2,974 ) Withholding tax 39,248 81,543 40,281 1,359 Land value increment tax - 249,210 - - Income tax expense recognized in profit or loss $ 4,311,073 $ 5,390,844 $ 6,523,603 $ 220,094 For the years ended December 31, 2015, 2016 and 2017, the Group applied a tax rate of 17% for resident entities subject to the Income Tax Law of the ROC; for the subsidiaries located in China, the applied tax rate was 25%; and for other jurisdictions, the Group measures taxes by using the applicable tax rate for each individual jurisdiction. In February 2018, it was announced by the President that the Income Tax Law of the ROC was amended and, starting from 2018, the corporate income tax rate will be adjusted from 17% to 20%. In addition, the tax rate applicable to 2018 unappropriated earnings will be reduced from 10% to 5%. Deferred tax assets and deferred tax liabilities recognized as at December 31, 2017 are expected to be adjusted and would increase by NT$201,965 thousand (US$6,814 thousand) and NT$788,556 thousand (US$26,604 thousand), respectively, in 2018. As the status of 2018 appropriations of earnings is uncertain, the potential income tax consequences of 2017 unappropriated earnings are not reliably determinable. b. Income tax recognized directly in equity For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Deferred income tax Related to employee share options $ (33 ) $ (204 ) $ 262 $ 9 c. Income tax recognized in other comprehensive income For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Deferred income tax Related to remeasurement of defined benefit plans $ 11,002 $ 73,637 $ (51,217 ) $ (1,728 ) d. Current tax assets and liabilities December 31 2016 2017 NT$ NT$ US$ (Note 4) Current tax assets Tax refund receivable $ 260,559 $ 28,458 $ 960 Prepaid income tax 211,193 232,084 7,830 $ 471,752 $ 260,542 $ 8,790 Current tax liabilities Income tax payable $ 6,846,350 $ 7,619,328 $ 257,062 e. Deferred tax assets and liabilities The Group offset certain deferred tax assets and deferred tax liabilities which met the offset criteria. The movements of deferred tax assets and deferred tax liabilities were as follows: Balance at January 1 Recognized in Profit or Loss Recognized in Other Comprehensive Income Recognized in Equity Exchange Differences Acquisitions through business combinations Balance at December 31 NT$ NT$ NT$ NT$ NT$ NT$ NT$ Year ended December 31, 2015 Temporary differences Property, plant and equipment $ (2,431,855 ) $ (1,083,273 ) $ - $ - $ 10,670 $ - $ (3,504,458 ) Defined benefit obligation 796,642 20,398 11,002 - 17,897 - 845,939 FVTPL financial instruments (170,059 ) (62,152 ) - - 13 - (232,198 ) Others 1,166,297 229,799 - (33 ) (11,076 ) - 1,384,987 (638,975 ) (895,228 ) 11,002 (33 ) 17,504 - (1,505,730 ) Loss carry-forward 519,898 812,217 - - (8,538 ) - 1,323,577 Investment credits 452,331 (32,904 ) - - (68,308 ) - 351,119 Others (853 ) 853 - - - - - $ 332,401 $ (115,062 ) $ 11,002 $ (33 ) $ (59,342 ) $ - $ 168,966 Year ended December 31, 2016 Temporary differences Property, plant and equipment $ (3,504,458 ) $ (182,291 ) $ - $ - $ (72,098 ) $ - $ (3,758,847 ) Defined benefit obligation 845,939 (48,601 ) 73,637 - 2,509 - 873,484 FVTPL financial instruments (232,198 ) 212,737 - - (1,902 ) - (21,363 ) Others 1,384,987 (283,179 ) - (204 ) (21,780 ) - 1,079,824 (1,505,730 ) (301,334 ) 73,637 (204 ) (93,271 ) - (1,826,902 ) Loss carry-forward 1,323,577 (110,967 ) - - (91,008 ) 2,939 1,124,541 Investment credits 351,119 56,862 - - (25,245 ) - 382,736 $ 168,966 $ (355,439 ) $ 73,637 $ (204 ) $ (209,524 ) $ 2,939 $ (319,625 ) Year ended December 31, 2017 Temporary differences Property, plant and equipment $ (3,758,847 ) $ (101,576 ) $ - $ - $ (18,643 ) $ - $ (3,879,066 ) Defined benefit obligation 873,484 (26,736 ) (51,217 ) - (15,291 ) - 780,240 FVTPL financial instruments (21,363 ) (86,342 ) - - 2,802 - (104,903 ) Others 1,079,824 (22,748 ) - 262 (28,929 ) - 1,028,409 (1,826,902 ) (237,402 ) (51,217 ) 262 (60,061 ) - (2,175,320 ) Loss carry-forward 1,124,541 (456,246 ) - - 13,146 - 681,441 Investment credits 382,736 138,002 - - 13,475 - 534,213 $ (319,625 ) $ (555,646 ) $ (51,217 ) $ 262 $ (33,440 ) $ - $ (959,666 ) Balance at January 1 Recognized in Profit or Loss Recognized in Other Comprehensive Income Recognized in Equity Exchange Differences Acquisitions through business combinations Balance at December 31 US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Year ended December 31, 2017 Temporary differences Property, plant and equipment $ (126,817 ) $ (3,427 ) $ - $ - $ (629 ) $ - $ (130,873 ) Defined benefit obligation 29,470 (902 ) (1,728 ) - (516 ) - 26,324 FVTPL financial instruments (721 ) (2,913 ) - - 94 - (3,540 ) Others 36,431 (767 ) - 9 (976 ) - 34,697 (61,637 ) (8,009 ) (1,728 ) 9 (2,027 ) - (73,392 ) Loss carry-forward 37,940 (15,393 ) - - 444 - 22,991 Investment credits 12,913 4,656 - - 454 - 18,023 $ (10,784 ) $ (18,746 ) $ (1,728 ) $ 9 $ (1,129 ) $ - $ (32,378 ) f. Items for which no deferred tax assets have been recognized Unrecognized deferred tax assets related to loss carry-forward, investment credits and deductible temporary differences were summarized as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Loss carry-forward $ 652,593 $ 542,054 $ 18,288 Investment credits 280,068 - - Deductible temporary differences 904,441 712,141 24,026 $ 1,837,102 $ 1,254,195 $ 42,314 The unrecognized loss carry-forward will expire through 2030 and the unrecognized investment credits will expire through 2018. g. Information about unused loss carry-forward, unused investment credits, tax-exemption and other tax relief As of December 31, 2017, the unused loss carry-forward comprised of: Year of Expiry NT$ US$ (Note 4) 2018 $ 230,656 $ 7,782 2019 34,981 1,180 2020 615,327 20,760 2021 164,377 5,546 2022 and thereafter 178,154 6,011 $ 1,223,495 $ 41,279 As of December 31, 2017, unused investment credits comprised of: Remaining Creditable Amount Tax Credit Source NT$ US$ Expiry Year (Note 4) Purchase of machinery and equipment $ 518,790 $ 17,503 2018 Others 15,423 520 2022 and thereafter $ 534,213 $ 18,023 As of December 31, 2017, profits attributable to the following expansion projects were exempted from income tax for a 5-year period: Tax-exemption Period Construction and expansion of 2007 by the Company 2016.01-2020.12 Construction and expansion of 2008 by the Company 2014.01-2018.12 Construction and expansion of 2008 by ASE Test Inc. 2014.01-2018.12 Construction and expansion of 2009 by ASE Test Inc. 2018.01-2022.12 Expansion of 2008 by ASE Electronics Inc. 2016.01-2020.12 Some China subsidiaries qualified as high technology enterprises were entitled to a reduced income tax rate of 15% and were eligible to deduct certain times of research and development expenses from their taxable income. h. Unrecognized deferred tax liabilities associated with investments As of December 31, 2016 and 2017, the taxable temporary differences associated with the investments in subsidiaries for which no deferred tax liabilities have been recognized were NT$14,417,873 thousand and NT$16,401,422 thousand (US$553,354 thousand), respectively. i. Integrated income tax As of December 31, 2016 and 2017, unappropriated earnings were all generated on and after January 1, 1998. As of December 31, 2016 and 2017, the balance of the Imputation Credit Account was NT$3,328,374 thousand and NT$4,003,283 thousand (US$135,064 thousand), respectively. The creditable ratio for the distribution of earnings of 2016 was 10.01%. Since the amended Income Tax Act published in February 2018 abolished the imputation tax system, no creditable ratio for distribution of earnings in 2018 is expected. j. Income tax assessments Income tax returns of ASE Inc. have been examined by authorities in 2012, 2014 and 2015 and its ROC subsidiaries have been examined by authorities through 2013 to 2015. ASE Inc. disagreed with the result of examinations relating to its income tax returns for 2014 and 2015 and appealed to the tax authorities. The related income tax expenses in the years resulting from the examinations have been accrued in respective tax years or in the year of the settlement.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
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Earnings Per Share	26. EARNINGS PER SHARE The earnings and weighted average number of ordinary shares outstanding in the computation of earnings per share were as follows: Net profit for the year For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Profit for the year attributable to owners of the Company $ 19,732,148 $ 21,324,423 $ 22,819,119 $ 769,876 Effect of potentially dilutive ordinary shares: Employee share options issued by subsidiaries - (374,359 ) (813,627 ) (27,450 ) Investments in associates (210,126 ) (494,388 ) (367,687 ) (12,405 ) Convertible bonds 901,187 (1,165,506 ) 93,781 3,164 Earnings used in the computation of diluted earnings per share $ 20,423,209 $ 19,290,170 $ 21,731,586 $ 733,185 Weighted average number of ordinary shares outstanding For the Year Ended December 31 2015 2016 2017 Weighted average number of ordinary shares in computation of basic earnings per share 7,652,773 7,662,870 8,160,887 Effect of potentially dilutive ordinary shares: Convertible bonds 455,671 515,295 124,911 Employee share options 86,994 59,218 39,868 Employees’ compensation 54,626 46,746 43,574 Weighted average number of ordinary shares in computation of diluted earnings per share 8,250,064 8,284,129 8,369,240 For purposes of the ADS calculation, the denominator represents the above-mentioned weighted average outstanding shares divided by five (one ADS represents five ordinary shares). The numerator was the same. The Group is able to settle the employees’ compensation by cash or shares. The Group assumed that the entire amount of the compensation would be settled in shares and the resulting potential shares were included in the weighted average number of ordinary shares outstanding used in the computation of diluted earnings per share if the effect is dilutive. Such dilutive effect of the potential shares was included in the computation of diluted earnings per share until the shareholders approve the number of shares to be distributed to employees at their meeting in the following year. The third unsecured convertible overseas bonds issued by the Company were anti-dilutive for the year ended December 31, 2017 and were excluded from the computation of diluted earnings per share for the same period.

Share-based Payment Arrangement

Share-based Payment Arrangements	12 Months Ended
	Dec. 31, 2017
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Share-based Payment Arrangements	27. SHARE-BASED PAYMENT ARRANGEMENTS a. Employee share option plans of the Company and its subsidiaries In order to attract, retain and reward employees, ASE Inc. has five employee share option plans for full-time employees of the Group. Each share option represents the right to purchase one ordinary share of ASE Inc. when exercised. Under the terms of the plans, share options are granted at an exercise price equal to or not less than the closing price of the ordinary shares listed on the TSE at the grant date. The option rights of these plans are valid for 10 years, non-transferable and exercisable at certain percentages subsequent to the second anniversary of the grant date. For any subsequent changes in the Company’s capital structure, the exercise price is accordingly adjusted. ASE Inc. Option Plans Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (NT$) Thousands) (NT$) Thousands) (NT$) Balance at January 1 209,745 $ 20.7 252,607 $ 26.6 210,795 $ 27.3 Options granted 94,270 36.5 - - - - Options forfeited (1,975 ) 30.3 (6,056 ) 34.6 (5,407 ) 36.3 Options expired (730 ) 11.1 - - (1,790 ) 21.1 Options exercised (48,703 ) 20.6 (35,756 ) 20.9 (67,637 ) 21.0 Balance at December 31 252,607 26.6 210,795 27.3 135,961 30.2 Options exercisable, end of year 158,103 20.8 123,007 20.8 85,642 26.5 Weighted-average fair value of options granted (NT$) $ 7.18~7.39 $ - $ - The weighted average share price at exercise dates of share options for the years ended December 31, 2015, 2016 and 2017 was NT$38.8, NT$36.2 and NT$37.6 (US$1.27), respectively. The option rights of the plan which was granted in 2007, was expired in December 2017, of which shares had not been exercised and, therefore, NT$47,087 thousand (US$1,589 thousand) was reclassified from capital surplus arising from exercised employee share options to capital surplus arising from expired employee share options. Information about the Company’s outstanding share options at each balance sheet date was as follows: Range of Exercise Price Per Share (NT$) Weighted Average Remaining Contractual Life (Years) December 31, 2016 4 th $ 20.4-22.6 2.5 5 th 36.5 8.7 December 31, 2017 4 th 20.4-22.6 2.5 5 th 36.5 7.7 ASE Mauritius Inc. Option Plan ASE Mauritius Inc. has an employee share option plan for full-time employees of the Group which granted 30,000 thousand units in December 2007. Under the terms of the plan, each unit represents the right to purchase one ordinary share of ASE Mauritius Inc. when exercised. The option rights of the plan are valid for 10 years, non-transferable and exercisable at certain percentages subsequent to the second anniversary of the grant date. The option rights of the plan was expired in December 2017 , of which shares had not been exercised and, therefore, NT$159,200 thousand (US$5,371 thousand) was reclassified from non-controlling interest to capital surplus arising from expired employee share options. Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (US$) Thousands) (US$) Thousands) (US$) Balance at January 1 28,545 $ 1.7 28,470 $ 1.7 28,470 $ 1.7 Options forfeited (75 ) 1.7 - - (250 ) 1.7 Options expired - - - - (28,220 ) 1.7 Balance at December 31 28,470 1.7 28,470 1.7 - - Options exercisable, end of year 28,470 1.7 28,470 1.7 - - USIE Option Plans The terms of the plans issued by USIE were the same with those of the Company’s option plans. Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (US$) Thousands) (US$) Thousands) (US$) Balance at January 1 34,159 $ 2.1 29,695 $ 2.1 25,933 $ 2.2 (continued) For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (US$) Thousands) (US$) Thousands) (US$) Options forfeited (84 ) $ 2.8 - $ - - $ - Options exercised (4,380 ) 1.9 (3,762 ) 2.0 (377 ) 1.9 Balance at December 31 29,695 2.1 25,933 2.2 25,556 2.2 Options exercisable, end of year 28,106 2.1 25,933 2.2 25,556 2.2 (concluded) Information about USIE’s outstanding share options at each balance sheet date was as follows: Range of Exercise Price Per Share (US$) Weighted Average Remaining Contractual Life (Years) December 31, 2016 1 st $ 1.5 4.0 2 nd rd 2.4-2.9 3.9 December 31, 2017 1 st $ 1.5 3.0 2 nd rd 2.4-2.9 2.9 In 2016 and 2017, the Group’s shareholdings of USIE decreased due to USIE’s share options had been exercised. The transaction was accounted for as an equity transaction since the Group did not cease to have control over USIE and, as a result, capital surplus was decreased by NT$444,320 thousand and NT$52,388 thousand (US$1,767 thousand) in 2016 and 2017, respectively. USISH Option Plans In November 2015, the shareholders of USISH approved a share option plan for the employees of USISH. Each unit represents the right to purchase one ordinary share of USISH when exercised. The options are valid for 10 years, non-transferable and exercisable at certain percentages subsequent to the second anniversary of the grant date incorporated with certain performance conditions. For any subsequent changes in USISH’s capital structure, the exercise price is accordingly adjusted. Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (CNY) Thousands) (CNY) Thousands) (CNY) Balance at December 31 - $ - 26,627 $ 15.5 24,997 $ 15.5 (continued) For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (CNY) Thousands) (CNY) Thousands) (CNY) Options granted 26,640 $ 15.5 - $ - - $ - Options forfeited (13 ) 15.5 (1,630 ) 15.5 (2,656 ) 15.5 Balance at December 31 26,627 15.5 24,997 15.5 22,341 15.5 Options exercisable, end of year - - - - 8,896 15.5 (concluded) As of December 31, 2016 and 2017, the remaining contractual life of the share options was 8.9 years and 7.9 years, respectively. b. Fair value of share options Share options granted by the Company and USISH in 2015 were measured using the Hull & White Model (2004) incorporated with Ritchken’s Trinomial Tree Model (1995) and the Black-Scholes Option Pricing Model, respectively, and the inputs to the models were as follows: ASE Inc. USISH Share price at the grant date NT$36.5 CNY15.2 Exercise prices NT$36.5 CNY15.5 Expected volatility 27.02% 40.33%-45.00% Expected lives 10 years 10 years Expected dividend yield 4.00% 0.87% Risk free interest rates 1.34% 3.06%-3.13% Expected volatility was based on the historical share price volatility over the past 10 years of ASE Inc. and the comparable companies of USISH, respectively. Under the Hull & White Model (2004) incorporated with Ritchken’s Trinomial Tree Model (1995), the Company assumed that employees would exercise the options after vesting date when the share price was 1.88 times the exercise price to allow for the effects of early exercise. In December 2015, USIE had modified the terms of its option plan granted in 2007 to extend the valid period from 12 years to 13 years, respectively. The incremental fair value of NT$13,721 thousand were all recognized as employee benefits expense in 2015, since the options were all vested. Employee benefits expense recognized on employee share options was NT$133,496 thousand, NT$470,788 thousand and NT$354,765 thousand (US$11,969 thousand) for the years ended December 31, 2015, 2016 and 2017, respectively. c. New shares reserved for subscription by employees under cash capital increase In December 2016, the board of directors approved the cash capital increase and, as required under the Company Act of the ROC, simultaneously granted options to employees to purchase 10% of such newly issued shares. The grant of the options was accounted for as employee options, accordingly a share-based compensation, and was measured at fair value in accordance with IFRS 2. The Group recognized employee benefits expense and capital surplus arising from exercised employee share options of NT$84,000 thousand (US$2,834 thousand) in full at the grant date (also the vested date), of which 4,836 thousand shares has not been exercised and, therefore, NT$13,541 thousand (US$457 thousand) was reclassified from capital surplus arising from exercised employee share options to capital surplus arising from expired employee share options. Information about the Company’s employee share options related to the aforementioned newly issued shares was as follows: Number of Options (In Thousand) Options granted for the year ended December 31, 2017 30,000 Options exercised for the year ended December 31, 2017 25,164 Weighted-average fair value of options granted (NT$ per share) $ 2.80 Fair value was measured using the Black-Scholes Option Pricing Model and the inputs to the model were as follows: Share price at the grant date NT$36.55 per share Exercise price NT$34.30 per share Expected volatility 27.15% Expected lives 47 days Expected dividend yield - Risk free interest rate 0.37% Expected volatility was based on the Company’s historical share prices volatility

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2017
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Business Combinations	28. BUSINESS COMBINATIONS a. Subsidiary acquired Principal Activity Date of Acquisition Proportion of Voting Equity Interests Acquired Cash Consideration NT$ TLJ Engaged in information software services May 3, 2016 60 % $ 89,998 In May 2016, the Company’s subsidiary, ASE Test, Inc., acquired 60% shareholdings of TLJ with a total consideration determined primarily based on independent professional appraisal reports. NT$41,739 thousand out of the total consideration was paid to key management personnel and related parties. b. Assets acquired and liabilities assumed at the date of acquisition NT$ Current assets $ 16,645 Non-current assets 108,486 Current liabilities (7,599 ) Fair value of identifiable net assets acquired $ 117,532 c. Goodwill recognized on acquisition NT$ Consideration transferred (paid in cash) $ 89,998 Add: Non-controlling interests 42,857 Less: Fair value of identifiable net assets acquired (117,532 ) Goodwill recognized on acquisition $ 15,323 The non-controlling interest recognized at the acquisition date was measured at its fair value. The goodwill recognized mainly represents the control premium. In addition, the consideration paid for the acquisition effectively included amounts attributed to the benefits of expected revenue growth and future market development of TLJ. These benefits are not recognized separately from goodwill because they do not meet the recognition criteria for identifiable intangible assets. d. Net cash outflow on acquisition of subsidiaries NT$ Consideration paid in cash $ 89,998 Less: Cash acquired (16,561 ) $ 73,437 e. In the second quarter in 2017, the Group has completed the identification of the difference between the cost of the investment and the Group’s share of the net fair value of TLJ’s identifiable assets and liabilities and therefore, the Company has retrospectively adjusted the comparative consolidated financial statements for prior periods. As of December 31, 2016, the retrospective adjustments are summarized as follows: After Retrospectively Adjusted Before Retrospectively Adjusted NT$ NT$ December 31, 2016 Goodwill $ 10,490,309 $ 10,558,878 Other intangible assets $ 1,617,261 $ 1,560,989 For the year ended December 31, 2016 Operating costs $ 221,696,922 $ 221,689,888 Operating expenses $ 26,526,815 $ 26,485,716 The aforementioned retrospective adjustments are accordingly recorded as a decrease of retained earnings of NT$28,880 thousand and as an increase of non-controlling interests of NT$16,583 thousand as of December 31, 2016.

Disposal of Subsidiaries

Disposal of Subsidiaries	12 Months Ended
	Dec. 31, 2017
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Disposal of Subsidiaries	29. DISPOSAL OF SUBSIDIARIES The Group entered into an agreement to dispose of KSDY. The disposal was completed in June 2017 and as a result, the Group lost its control over KSDY. a. Gain on disposal of subsidiaries NT$ US$ (Note 4) Total consideration $ 7,046,464 $ 237,735 Net assets disposed of (1,457,007 ) (49,157 ) Gain on disposal of KSDY $ 5,589,457 $ 188,578 b. Analysis of assets and liabilities on the date control was lost NT$ US$ (Note 4) Current assets Cash and cash equivalents $ 29,133 $ 983 Inventories related to real estate business 1,427,874 48,174 Net assets disposed of $ 1,457,007 $ 49,157

Equity Transaction with Non-con

Equity Transaction with Non-controlling Interests	12 Months Ended
	Dec. 31, 2017
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Equity Transaction with Non-controlling Interests	30. EQUITY TRANSACTION WITH NON-CONTROLLING INTERESTS In April 2015, the Group’s subsidiary, USIE, sold its shareholdings of 54,000 thousand ordinary shares of USISH amounting to CNY1,992,060 thousand and, as a result, the Group’s shareholdings of USISH decreased from 82.1% to 77.2%. The transaction was accounted for as an equity transaction since the Group did not cease to have control over USISH and, as a result, capital surplus was increased by NT$7,197,510 thousand. In February 2016, USIE repurchased its own 4,501 thousand outstanding ordinary shares and, as a result, the Group’s shareholdings of USIE increased from 96.7% to 98.8%. The transaction was accounted for as an equity transaction since the Group did not cease to have control over USIE and capital surplus was decreased by NT$1,912,887 thousand in 2016. In February 2016, the Company disposed 39,603 thousand shares in USI to the Company’s subsidiary, UGTW, at NT$20 per share with a total consideration of NT$792,064 thousand and, as a result, the Group’s shareholdings of USI decreased from 99.0% to 76.5%. The transaction was accounted for as an equity transaction since the Group did not cease to have control over USI and capital surplus was decreased by NT$20,552 thousand in 2016. In January 2017, USI completed its cash capital increase of NT$1,000,000 thousand (US$33,738 thousand) and the Group’s shareholdings of USI increased from 75.2% to 75.7% since the Group did not proportional subscribe for additional new shares. The transaction was accounted for as an equity transaction since the Group did not cease to have control over USI and capital surplus was increased by NT$3,055 thousand (US$103 thousand) in 2017. In January 2018, the shareholders’ meeting of the Company’s subsidiary, USIE, approved to repurchase its own 3,738,420 outstanding ordinary shares at US$17.49 per share. In February 2018, the board of directors of USIE resolved February 26, 2018 as the record date for capital reduction and then the repurchased ordinary shares will be subsequently cancelled.

Non-cash Transactions

Non-cash Transactions	12 Months Ended
	Dec. 31, 2017
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Non-cash Transactions	31. NON-CASH TRANSACTIONS a. Except those discussed in Note 11, for the years ended December 31, 2015, 2016 and 2017, the Group entered into the following non-cash investing activities which were not reflected in the consolidated statements of cash flows: For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Payments for property, plant and equipment Purchase of property, plant and equipment $ 28,280,821 $ 27,680,862 $ 23,677,682 $ 798,842 Increase (decrease) in prepayments for property, plant and equipment (recorded under the line item of other non-current assets) (267,334 ) (89,337 ) 90,560 3,055 (Increase) decrease in payables for property, plant and equipment (recorded under the line item of other payables) 2,314,772 (823,171 ) 982,260 33,140 (Continued) For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Capitalized borrowing costs (48,135 ) (54,191 ) (51,262 ) (1,729 ) $ 30,280,124 $ 26,714,163 $ 24,699,240 $ 833,308 Proceeds from disposal of property, plant and equipment Consideration from disposal of property, plant and equipment $ 201,766 $ 692,826 $ 1,487,334 $ 50,180 (Increase) decrease in other receivables 41,265 (22,626 ) 876 30 $ 243,031 $ 670,200 $ 1,488,210 $ 50,210 Investment properties Purchase of investment properties $ - $ - $ 186,535 $ 6,293 Capitalized borrowing costs - - (13 ) - $ - $ - $ 186,522 $ 6,293 Payments for other intangible assets Purchase of other intangible assets $ 491,135 $ 675,144 $ 277,825 $ 9,373 Decrease (increase) in other payables - (120,938 ) 60,159 2,030 Increase in other non-current liabilities - (40,313 ) - - $ 491,135 $ 513,893 $ 337,984 $ 11,403 Net cash inflow from disposal of subsidiaries Consideration from disposal of subsidiaries $ - $ - $ 7,046,464 $ 237,735 Increase in other payables - - 3,552 120 Cash and cash equivalents disposed of - - (29,133 ) (983 ) $ - $ - $ 7,020,883 $ 236,872 (Concluded) b. As those discussed in Note 20, the bonds holders of the third unsecured convertible overseas bonds issued by the Company in September 2013 have exercised the conversion right in 2017 as a result of an increase in the Company’s capital and capital surplus by NT$4,242,577 thousand (US$143,137 thousand) and NT$9,657,905 thousand (US$325,840 thousand), respectively.

Operating Lease Arrangements

Operating Lease Arrangements	12 Months Ended
	Dec. 31, 2017
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Operating Lease Arrangements	32. OPERATING LEASE ARRANGEMENTS Except those discussed in Note 18, the Company and its subsidiary, ASE Test, Inc., lease the land on which their buildings are located under various operating lease agreements with the ROC government expiring through January 2037. The agreements grant these entities the option to renew the leases and reserve the right for the lessor to adjust the lease payments upon an increase in the assessed value of the land and to terminate the leases under certain conditions. In addition, the Group leases buildings, machinery and equipment under operating leases. The subsidiaries’ offices located in U.S.A. and Japan, etc. are leased from other parties and the lease terms will expire through 2018 to 2023 with the option to renew the leases upon expiration. The Group recognized rental expense of NT$1,390,821 thousand, NT$1,411,533 thousand and NT$ 1,193,477 thousand (US$40,266 thousand) for the years ended December 31, 2015, 2016 and 2017, respectively, from the aforementioned operating lease arrangements and the land use rights disclosed in Note 18. As of December 31, 2017, the future minimum lease payments of non-cancellable operating lease commitments were as follows: NT$ US$ (Note 4) Less than 1 year $ 246,026 $ 8,300 1-5 years 439,408 14,825 More than 5 years 419,232 14,144 $ 1,104,666 $ 37,269

Capital Management

Capital Management	12 Months Ended
	Dec. 31, 2017
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Capital Management	33. CAPITAL MANAGEMENT The capital structure of the Group consists of debt and equity. The Group manages its capital to ensure that entities in the Group will be able to continue as going concerns while maximizing the return to shareholders through the optimization of the debt and equity balance. Key management personnel of the Group periodically reviews the cost of capital and the risks associated with each class of capital. In order to balance the overall capital structure, the Group may adjust the amount of dividends paid to shareholders, the number of new shares issued or repurchased, and the amount of new debt issued or existing debt redeemed. The Group is not subject to any externally imposed capital requirements except those discussed in Note 19.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2017
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Financial Instruments	34. FINANCIAL INSTRUMENTS a. Fair value of financial instruments that are not measured at fair value 1) Fair value of financial instruments not measured at fair value but for which fair value is disclosed Except bonds payable measured at amortized cost, the management considered that the carrying amounts of financial assets and financial liabilities not measured at fair value approximate their fair values. The carrying amounts and fair value of bonds payable as of December 31, 2016 and 2017, respectively, were as follows: Carrying Amount Fair Value NT$ US$ (Note 4) NT$ US$ (Note 4) December 31, 2016 $ 36,999,903 $ 37,300,356 December 31, 2017 23,142,780 $ 780,796 23,247,085 $ 784,315 2) Fair value hierarchy The aforementioned fair value hierarchy of bonds payable was Level 3 which was determined based on discounted cash flow analysis with the applicable yield curve for the duration or the latest trading prices. The significant unobservable inputs is discount rates that reflected the credit risk of various counterparties and the latest trading prices. b. Fair value of financial instruments that are measured at fair value on a recurring basis 1) Fair value hierarchy Level 1 Level 2 Level 3 Total NT$ NT$ NT$ NT$ December 31, 2016 Financial assets at FVTPL Financial assets designated as at FVTPL Private-placement convertible bonds $ - $ 100,583 $ - $ 100,583 Derivative financial assets Forward exchange contracts - 462,339 - 462,339 Forward currency options - 66,872 - 66,872 Non-derivative financial assets held for trading Quoted shares $ 1,855,073 $ - $ - $ 1,855,073 Open-end mutual funds 584,945 - - 584,945 $ 2,440,018 $ 629,794 $ - $ 3,069,812 Available-for-sale financial assets Unquoted shares $ - $ - $ 631,418 $ 631,418 Limited Partnership - - 273,372 273,372 Open-end mutual funds 243,458 - - 243,458 Quoted shares 146,786 - - 146,786 $ 390,244 $ - $ 904,790 $ 1,295,034 Financial liabilities at FVTPL Derivative financial liabilities Conversion option, redemption option and put option of convertible bonds $ - $ 1,213,890 $ - $ 1,213,890 Swap contracts - 422,934 - 422,934 Forward exchange contracts - 108,912 - 108,912 Foreign currency option contracts - 17,924 - 17,924 $ - $ 1,763,660 $ - $ 1,763,660 Level 1 Level 2 Level 3 Total NT$ US$ (Note 4) NT$ US$ (Note 4) NT$ US$ (Note 4) NT$ US$ (Note 4) December 31, 2017 Financial assets at FVTPL Financial assets designated as at FVTPL Private-placement convertible bonds $ - $ - $ 100,496 $ 3,391 $ - $ - $ 100,496 $ 3,391 Derivative financial assets Forward exchange contracts - - 61,325 2,069 - - 61,325 2,069 Swap contracts - - 60,538 2,042 - - 60,538 2,042 Non-derivative financial assets held for trading Quoted shares 4,410,732 148,810 - - - - 4,410,732 148,810 Open-end mutual funds 589,976 19,905 - - - - 589,976 19,905 $ 5,000,708 $ 168,715 $ 222,359 $ 7,502 $ - $ - $ 5,223,067 $ 176,217 Available-for-sale financial assets Unquoted shares $ - $ - $ - $ - $ 662,477 $ 22,350 $ 662,477 $ 22,350 Limited partnership - - - - 246,072 8,302 246,072 8,302 Quoted shares 279,791 9,440 - - - - 279,791 9,440 Open-end mutual funds 23,825 804 - - - - 23,825 804 $ 303,616 $ 10,244 $ - $ - $ 908,549 $ 30,652 $ 1,212,165 $ 40,896 Financial liabilities at FVTPL Derivative financial liabilities Swap contracts $ - $ - $ 652,107 $ 22,001 $ - $ - $ 652,107 $ 22,001 Forward exchange contracts - - 25,323 854 - - 25,323 854 $ - $ - $ 677,430 $ 22,855 $ - $ - $ 677,430 $ 22,855 For the financial assets and liabilities that were measured at fair value on a recurring basis held for the years ended December 31, 2016 and 2017, there were no transfers between Level 1 and Level 2 of the fair value hierarchy. 2) Reconciliation of Level 3 fair value measurements of financial assets The financial assets measured at Level 3 fair value were equity investments with no quoted prices classified as available-for-sale financial assets - non-current. Reconciliations for the years ended December 31, 2015, 2016 and 2017 were as follows: For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 778,866 $ 741,089 $ 904,790 $ 30,526 Purchases 2,010 495,928 2,649 89 Total gain or loss In profit or loss (15,891 ) (100,734 ) 28 1 In other comprehensive income 21,195 (202,565 ) 17,284 583 Disposals (45,091 ) (28,928 ) (16,202 ) (547 ) Balance at December 31 $ 741,089 $ 904,790 $ 908,549 $ 30,652 3) Valuation techniques and assumptions applied for the purpose of measuring fair value a) Valuation techniques and inputs applied for the purpose of measuring Level 2 fair value measurement Financial Instruments Valuation Techniques and Inputs Derivatives - swap contracts, forward exchange contracts and foreign currency option contracts Discounted cash flows - Future cash flows are estimated based on observable forward exchange rates at balance sheet dates and contract forward exchange rates, discounted at rates that reflected the credit risk of various counterparties. Derivatives - conversion option, redemption option and put option of convertible bonds Option pricing model - Incorporation of present value techniques and reflect both the time value and the intrinsic value of options Private-placement convertible bonds Discounted cash flows - Future cash flows are estimated based on observable stock prices at balance sheet dates and contract conversion prices, discounted at rates that reflected the credit risk of various counterparties. b) Valuation techniques and inputs applied for the purpose of measuring Level 3 fair value measurement The fair value of the Group’s investments in unquoted shares on Level 3 fair value measurement were measured using market approach based on investees’ recent financing activities, technical development, valuation of investees comparable companies, market conditions and other economic indicators. The fair values of investments in limited partnership are measured by estimating future cash inflows from disposal (net of transaction cost). The Group recognized an impairment loss of NT$90,000 thousand and NT$50,206 thousand (US$1,694 thousand) under the line item of other gains and losses in the consolidated statements of comprehensive income for the years ended December 31, 2016 and 2017, respectively. c. Categories of financial instruments December 31 2016 2017 NT$ NT$ US$ (Note 4) Financial assets FVTPL Designated as at FVTPL $ 100,583 $ 100,496 $ 3,391 Held for trading 2,969,229 5,122,571 172,826 Available-for-sale financial assets 1,295,034 1,212,165 40,896 Loans and receivables (Note 1) 92,082,628 103,973,567 3,507,881 Financial liabilities FVTPL Held for trading 1,763,660 677,430 22,855 Measured at amortized cost (Note 2) 168,397,006 139,561,999 4,708,569 Note 1: The balances included loans and receivables measured at amortized cost which comprise cash and cash equivalents, trade and other receivables and other financial assets. Note 2: The balances included financial liabilities measured at amortized cost which comprise short-term borrowings, trade and other payables, bonds payable and long-term borrowings. d. Financial risk management objectives and policies The derivative instruments used by the Group are to mitigate risks arising from ordinary business operations. All derivative transactions entered into by the Group are designated as either hedging or trading. Derivative transactions entered into for hedging purposes must hedge risk against fluctuations in foreign exchange rates and interest rates arising from operating activities. The currencies and the amount of derivative instruments held by the Group must match its hedged assets and liabilities denominated in foreign currencies. The Group’s risk management department monitors risks to mitigate risk exposures, reports unsettled position, transaction balances and related gains or losses to the Group’s chief financial officer on monthly basis. 1) Market risk The Group’s activities exposed it primarily to the financial risks of changes in foreign currency exchange rates and interest rates. Gains or losses arising from fluctuations in foreign currency exchange rates of a variety of derivative financial instruments were approximately offset by those of hedged items. Interest rate risk was not significant due to the cost of capital was expected to be fixed. There had been no change to the Group’s exposure to market risks or the manner in which these risks were managed and measured. a) Foreign currency exchange rate risk The Group had sales and purchases as well as financing activities denominated in foreign currency which exposed the Group to foreign currency exchange rate risk. The Group entered into a variety of derivative financial instruments to hedge foreign currency exchange rate risk to minimize the fluctuations of assets and liabilities denominated in foreign currencies. The carrying amounts of the Group’s foreign currency denominated monetary assets and liabilities (including those eliminated upon consolidation) as well as derivative instruments which exposed the Group to foreign currency exchange rate risk at each balance sheet date are presented in Note 39. The Group was principally subject to the impact to exchange rate fluctuation in US$ and JPY against NT$ or CNY. 1% is the sensitivity rate used when reporting foreign currency exchange rate risk internally to key management personnel and represents management’s assessment of the reasonably possible change in foreign currency exchange rates. The sensitivity analysis included financial assets and liabilities and inter-company receivables and payables within the Group. The changes in profit before income tax due to a 1% change in U.S. dollars and Japanese yen both against NT$ and CNY would be NT$18,000 thousand, NT$69,000 thousand and NT$101,000 thousand (US$3,408 thousand) for the years ended December 31, 2015, 2016 and 2017, respectively. Hedging contracts and hedged items have been taken into account while measuring the changes in profit before income tax. The abovementioned sensitivity analysis mainly focused on the foreign currency monetary items at the end of the year. As the year-end exposure did not reflect the exposure for the years ended December 31, 2015, 2016 and 2017, the abovementioned sensitivity analysis was unrepresentative of those years. b) Interest rate risk Except a portion of long-term borrowings and bonds payable at fixed interest rates, the Group was exposed to interest rate risk because group entities borrowed funds at floating interest rates. Changes in market interest rates will lead to variances in effective interest rates of borrowings from which the future cash flow fluctuations arise. The Group entered into a variety of derivative financial instruments to hedge interest rate risk to minimize the fluctuations of assets and liabilities denominated in interest rate. The carrying amounts of the Group’s financial assets and financial liabilities with exposure to interest rates at each balance sheet date were as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Fair value interest rate risk Financial liabilities $ 30,243,887 $ 17,552,955 $ 592,205 Cash flow interest rate risk Financial assets 29,977,709 39,880,736 1,345,504 Financial liabilities 65,800,323 42,270,321 1,426,124 For assets and liabilities with floating interest rates, a 100 basis point increase or decrease was used when reporting interest rate risk internally to key management personnel. If interest rates had been 100 basis points (1%) higher or lower and all other variables held constant, the Group’s profit before income tax for the years ended December 31, 2015, 2016 and 2017 would have decreased or increased approximately by NT$117,000 thousand, NT$358,000 thousand and NT$24,000 thousand (US$810 thousand), respectively. Hedging contracts and hedged items have been taken into account while measuring the changes in profit before income tax. The abovementioned sensitivity analysis mainly focused on the interest rate items at the end of the reporting period. As the period-end exposure did not reflect the exposure for the years ended December 31, 2015, 2016 and 2017, the abovementioned sensitivity analysis was unrepresentative of those periods. c) Other price risk The Group was exposed to equity or debt price risk through its investments in financial assets at FVTPL, including private-placement convertible bonds, quoted shares, open-end mutual funds, and available-for-sale financial assets. If equity or debt prices were 1% higher or lower, profit before income tax for the years ended December 31, 2015, 2016 and 2017 would have increased or decreased approximately by NT$7,100 thousand, NT$26,000 thousand and NT$52,000 thousand (US$1,754 thousand), respectively, and other comprehensive income before income tax for the years ended December 31, 2015, 2016 and 2017 would have increased or decreased approximately by NT$10,000 thousand, NT$13,000 thousand and NT$13,000 thousand (US$439 thousand), respectively. In addition, the Group was also exposed to the Company’s ordinary share price risk through Bonds Options recognized as financial liabilities held for trading. 7% is the sensitivity rate used when reporting price risk internally to key management personnel. If the Company’s ordinary share price increased or decreased by 7%, profit before income tax for the years ended December 31, 2015, and 2016 would have decreased approximately by NT$605,000 thousand and NT$510,000 thousand, respectively, or increased approximately by NT$638,000 thousand and NT$445,000 thousand, respectively. 2) Credit risk Credit risk refers to the risk that counterparty will default on its contractual obligations resulting in financial loss to the Group. The Group’s credit risk arises from cash and cash equivalents, receivables and other financial assets. The Group’s maximum exposure to credit risk was the carrying amounts of financial assets in the consolidated balance sheets. The Group dealt with counterparties creditworthy and has a credit policy and trade receivable management procedures to ensure recovery and evaluation of trade receivables. Except for those discussed in Note 9, the Group’s counterparties consisted of a large number of customers and banks and there was no significant concentration of credit risk exposure. 3) Liquidity risk The Group manages liquidity risk by maintaining adequate working capital and banking facilities to fulfill the demand for cash flow used in the Group’s operation and capital expenditure. The Group also monitors its compliance with all the loan covenants. Liquidity risk is not considered to be significant. In the table below, financial liabilities with a repayment on demand clause were included in the earliest time band regardless of the probability of counter-parties choosing to exercise their rights. The maturity dates for other non-derivative financial liabilities were based on the agreed repayment dates. To the extent that interest flows are floating rate, the undiscounted amounts were derived from the interest rates at each balance sheet date. On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year 1 to 5 Years More than 5 Years NT$ NT$ NT$ NT$ NT$ December 31, 2016 Non-derivative financial liabilities Non-interest bearing $ 23,907,221 $ 20,553,395 $ 4,360,322 $ 42,285 $ 190,941 Floating interest rate liabilities 9,733,727 5,232,407 6,634,931 44,504,416 1,728,448 (continued) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year 1 to 5 Years More than 5 Years NT$ NT$ NT$ NT$ NT$ Fixed interest rate liabilities $ 5,360,644 $ 1,019,221 $ 10,549,983 $ 28,553,095 $ 2,062,500 $ 39,001,592 $ 26,805,023 $ 21,545,236 $ 73,099,796 $ 3,981,889 (concluded) December 31, 2017 Non-derivative financial liabilities Non-interest bearing $ 30,695,797 $ 18,387,296 $ 4,549,468 $ 2,807 $ 176,199 Floating interest rate liabilities 6,641,541 4,153,830 5,101,178 27,196,245 900,310 Fixed interest rate liabilities 8,522,765 7,526,270 1,526,449 11,902,335 6,462,396 $ 45,860,103 $ 30,067,396 $ 11,177,095 $ 39,101,387 $ 7,538,905 On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year 1 to 5 Years More than 5 Years US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) December 31, 2017 Non-derivative financial liabilities Non-interest bearing $ 1,035,621 $ 620,354 $ 153,491 $ 95 $ 5,945 Floating interest rate liabilities 224,073 140,143 172,104 917,552 30,375 Fixed interest rate liabilities 287,543 253,923 51,500 401,563 218,029 $ 1,547,237 $ 1,014,420 $ 377,095 $ 1,319,210 $ 254,349 The amounts included above for floating interest rate instruments for non-derivative financial liabilities was subject to change if changes in floating interest rates differ from those estimates of interest rates determined at each balance sheet date. The following table detailed the Group’s liquidity analysis for its derivative financial instruments. The table was based on the undiscounted contractual net cash inflows and outflows on derivative instruments that settle on a net basis, and the undiscounted gross cash inflows and outflows on those derivatives that require gross settlement. When the amounts payable or receivable are not fixed, the amounts disclosed have been determined by reference to the projected interest rates as illustrated by the yield curves at each balance sheet date. On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year NT$ NT$ NT$ December 31, 2016 Net settled Forward exchange contracts $ 22,680 $ 13,320 $ - Foreign currency option contracts $ (344 ) $ - $ - Gross settled Forward exchange contracts Inflows $ 5,134,196 $ 912,213 $ - Outflows (5,245,724 ) (915,900 ) - (111,528 ) (3,687 ) - (continued) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year NT$ NT$ NT$ Swap contracts Inflows $ 5,345,159 $ 17,399,695 $ 43,537,500 Outflows (5,439,190 ) (17,540,927 ) (42,882,201 ) (94,031 ) (141,232 ) 655,299 $ (205,559 ) $ (144,919 ) $ 655,299 December 31, 2017 Net settled Forward exchange contracts $ (8,820 ) $ - $ - Gross settled Forward exchange contracts Inflows $ 3,711,302 $ 2,169,093 $ 390,379 Outflows (3,679,154 ) (2,138,635 ) (386,880 ) 32,148 30,458 3,499 Swap contracts Inflows 12,116,531 14,434,880 36,676,224 Outflows (12,189,576 ) (14,629,738 ) (36,452,898 ) (73,045 ) (194,858 ) 223,826 $ (40,897 ) $ (164,400 ) $ 227,325 (concluded) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year US$ (Note 4) US$ (Note 4) US$ (Note 4) December 31, 2017 Net settled Forward exchange contracts $ (298 ) $ - $ - (Continued) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year US$ (Note 4) US$ (Note 4) US$ (Note 4) Gross settled Forward exchange contracts Inflows $ 125,213 $ 73,181 $ 13,171 Outflows (124,128 ) (72,154 ) (13,154 ) 1,085 1,027 118 Swap contracts Inflows 408,790 487,007 1,237,389 Outflows (411,254 ) (493,581 ) (1,229,838 ) (2,464 ) (6,574 ) 7,551 $ (1,379 ) $ (5,547 ) $ 7,669 (Concluded) e. Reconciliation of liabilities arising from financing activities The table below details changes in the Group’s liabilities arising from financing activities, including both cash and non-cash changes. Liabilities arising from financing activities are those for which cash flows were, of future cash flows will be, classified in the Group’s condensed consolidated statement of cash flows as cash flows from financing activities. For the year ended December 31, 2017 Short-term borrowings Bonds payable Long-term borrowings Total NT$ NT$ NT$ NT$ Balance at January 1, 2017 $ 20,955,522 $ 36,999,903 $ 53,115,563 $ 111,070,988 Financing cash flows (2,038,993 ) (1,123,972 ) (16,473,381 ) (19,636,346 ) Non-cash changes Amortization of issuance cost - 319,463 5,790 325,253 Converted to ordinary shares in current period - (11,650,369 ) - (11,650,369 ) Effects of exchange rate changes (954,058 ) (1,402,245 ) (1,241,344 ) (3,597,647 ) Balance at December 31, 2017 $ 17,962,471 $ 23,142,780 $ 35,406,628 $ 76,511,879 Short-term borrowings Bonds payable Long-term borrowings Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1,2017 $ 707,001 $ 1,248,310 $ 1,792,023 $ 3,747,334 Financing cash flows (68,792 ) (37,920 ) (555,782 ) (662,494 ) Non-cash changes Amortization of issuance cost - 10,778 195 10,973 Converted to ordinary shares in current period - (393,062 ) - (393,062 ) Effects of exchange rate changes (32,188 ) (47,310 ) (41,881 ) (121,379 ) Balance at December 31, 2017 $ 606,021 $ 780,796 $ 1,194,555 $ 2,581,372

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
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Related Party Transactions	35. RELATED PARTY TRANSACTIONS Balances and transactions within the Group had been eliminated upon consolidation. Details of transactions between the Group and other related parties were disclosed as follows: a. Related parties In addition to those disclosed in Note 13 and NXP B.V. as a related party of the Group’s subsidiary, ASEN, over which NXP B.V. has significant influence, other related parties were as follows: Related Parties Relationship with the Corporation ASE Cultural and Educational Foundation Substantial related party Fu Hwa Construction Co., Ltd. Associate’s subsidiary b. The Company contributed each NT$100,000 thousand (US$3,374 thousand) to ASE Cultural and Educational Foundation during 2015, 2016 and 2017, respectively, for environmental charity in promoting the related domestic environmental protection and public service activities (Note 37). c. In 2016, the Company acquired patents and specific technology from DECA at NT$403,543 thousand, which was primarily based on independent professional appraisal reports. As of December 31, 2016 and 2017, NT$161,250 thousand and NT$93,000 thousand (US$3,138 thousand), respectively, has not been paid and was accrued under the line item of other payables and other non-current liabilities. d. The Company contracted with Fu Hwa Construction Co., Ltd. to construct a female employee dormitory on current leased land. Total consideration was primarily based on independent professional appraisal reports. During 2015 and 2016, the employee dormitory has been capitalized for NT$504,600 thousand and NT$875,000 thousand, respectively. The female employee dormitory has been completely constructed in 2016. As of December 31, 2016, NT$228,500 thousand has not been paid and was accrued under the line item of other payables, which was fully repaid in March 2017. e. In February 2016, USIE repurchased 1,801 thousand shares of USIE’s outstanding ordinary shares from the Group’s key management personnel with approximately NT$1,130,650 thousand. f. Compensation to key management personnel For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Short-term employee benefits $ 812,002 $ 790,460 $ 860,631 $ 29,036 Post-employment benefits 3,944 4,790 2,858 97 Share-based payments 17,937 11,547 - - $ 833,883 $ 806,797 $ 863,489 $ 29,133 The compensation to the Company’s key management personnel is determined according to personal performance and market trends.

Assets Pledged as Collateral or

Assets Pledged as Collateral or for Security	12 Months Ended
	Dec. 31, 2017
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Assets Pledged as Collateral or for Security	36. ASSETS PLEDGED AS COLLATERAL OR FOR SECURITY In addition to Note 9, the following assets were provided as collateral for bank borrowings and the tariff guarantees of imported raw materials: December 31 2016 2017 NT$ NT$ US$ (Note 4) Inventories related to real estate business $ 16,813,023 $ 4,822,043 $ 162,687 Investment properties - 7,151,382 241,275 Land use rights (recorded as long-term prepayment for lease) - 6,813,751 229,884 Other financial assets (including current and non-current) 220,228 66,726 2,251 $ 17,033,251 $ 18,853,902 $ 636,097

Significant Contingent Liabilit

Significant Contingent Liabilities and Unrecognized Commitments	12 Months Ended
	Dec. 31, 2017
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Significant Contingent Liabilities and Unrecognized Commitments	37. SIGNIFICANT CONTINGENT LIABILITIES AND UNRECOGNIZED COMMITMENTS In addition to those disclosed in other notes, significant commitments and contingencies of the Group as of each balance sheet date were as follows: a. As of December 31, 2016 and 2017, unused letters of credit of the Group were approximately NT$97,000 thousand and NT$20,000 thousand (US$675 thousand), respectively. b. As of December 31, 2016 and 2017, outstanding commitments to purchase property, plant and equipment of the Group were approximately NT$6,630,957 thousand and NT$7,019,377 thousand (US$236,821 thousand), respectively, of which NT$668,509 thousand and NT$294,194 thousand (US$9,926 thousand) had been prepaid, respectively. As of December 31, 2016 and 2017, the commitment that the Group has contracted for the construction related to our real estate business were approximately NT$1,574,822 thousand and NT$1,548,806 thousand (US$52,254 thousand), respectively. c. In consideration of corporate social responsibility for environmental protection, the Company’s board of directors, in December 2013, approved contributions to be made in the next 30 years, at a total amount of NT$3,000,000 thousand, at the minimum, to environmental protection efforts in Taiwan. In January 2018, the Company’s board of directors approved to contribute NT$100,000 thousand (US$3,374 thousand) to ASE Cultural& Educational Foundation for continuously implementing environmental effort in promoting the related domestic environmental protection and public service activities.

Significant Subsequent Events

Significant Subsequent Events	12 Months Ended
	Dec. 31, 2017
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Significant Subsequent Events	38. SIGNIFICANT SUBSEQUENT EVENTS In February 2018, Universal Global Electronics Co., Limited, a new subsidiary of the Group, has signed a joint venture agreement with other company and plans to form a joint venture in Brazil.

Significant Assets and Liabilit

Significant Assets and Liabilities Denominated in Foreign Currencies	12 Months Ended
	Dec. 31, 2017
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Significant Assets and Liabilities Denominated in Foreign Currencies	39. SIGNIFICANT ASSETS AND LIABILITIES DENOMINATED IN FOREIGN CURRENCIES The following information was aggregated by the foreign currencies other than functional currencies of the group entities and the exchange rates between foreign currencies and respective functional currencies were disclosed. The significant financial assets and financial liabilities denominated in foreign currencies were as follows: Foreign Currencies (In Thousand) Exchange Rate Carrying Amount (In Thousand) December 31, 2016 Monetary financial assets US$ $ 3,106,557 US$1=NT$32.25 $ 100,186,466 US$ 1,020,769 US$1=CNY6.9370 32,919,814 JPY 4,976,309 JPY1=NT$0.2756 1,371,471 JPY 9,277,760 JPY1=US$0.0085 2,556,951 Monetary financial liabilities US$ 3,013,288 US$1=NT$32.25 97,178,536 US$ 891,487 US$1=CNY6.9370 28,750,462 JPY 5,881,716 JPY1=NT$0.2756 1,621,001 JPY 9,543,756 JPY1=US$0.0085 2,630,259 December 31, 2017 Monetary financial assets US$ 3,065,296 US$1=NT$29.76 91,223,195 US$ 1,193,369 US$1=CNY6.5342 35,514,653 JPY 5,005,435 JPY1=NT$0.2642 1,322,436 JPY 8,113,284 JPY1=US$0.0089 2,143,530 (continued) Foreign Currencies (In Thousand) Exchange Rate Carrying Amount (In Thousand) Monetary financial liabilities US$ $ 2,902,995 US$1=NT$29.76 $ 86,393,137 US$ 1,007,629 US$1=CNY6.5342 29,987,042 JPY 5,415,677 JPY1=NT$0.2642 1,430,822 JPY 8,598,832 JPY1=US$0.0089 2,271,811 (concluded) The significant realized and unrealized foreign exchange gain (loss) were as follows: For the Year Ended December 31 2015 2016 2017 Functional Currencies Exchange Rate Net Foreign Exchange Gain (Loss) Exchange Rate Net Foreign Exchange Gain (Loss) Exchange Rate Net Foreign Exchange Gain NT$ NT$ NT$ US$ (Note 4) NT$ $ (695,510 ) $ 1,494,044 $ 4,130,243 $ 139,347 US$ US$1=NT$32.825 136,795 US$1=NT$32.25 203,258 US$1=NT$29.76 (244,802 ) (8,259 ) CNY CNY1=NT$5.0550 (271,358 ) CNY1=NT$4.649 224,393 CNY1=NT$4.5545 (337,630 ) (11,391 ) $ (830,073 ) $ 1,921,695 $ 3,547,811 $ 119,697

Others

Others	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Others	40. OTHERS a) On December 20, 2013, the Kaohsiung Environmental Protection Bureau (“KEPB”) imposed a fine of NT$102,014 thousand (“the Administrative Fine”) upon the Company for the violation of the Water Pollution Control Act. The Company filed an administrative appeal to nullify the Administrative Fine, which, however, was dismissed by the Kaohsiung City Government. The Company then filed a lawsuit with the Kaohsiung High Administrative Court seeking to revoke the dismissal decision made by the Kaohsiung City Government (the “Administrative Appeal Decision”) and the Administrative Fine, and to demand a refund of the fine paid by the Company. The judgment of the Kaohsiung High Administrative Court was rendered on March 22, 2016, ruling to revoke the Administrative Appeal Decision and the Administrative Fine, and to dismiss the other complaint filed by the Company (i.e., to demand a refund of the fine paid by the Company). The Company appealed against the unfavorable ruling on April 14, 2016. On June 8, 2017, the Supreme Administrative Court handed down a final and unappealable judgment which is in favor of the Company and ordered KEPB to return to the Company the fine already paid by the Company. b) For the future development and sustainable development of semiconductor industry , the Company’s board of directors approved in June 2016 to enter into and execute a joint share exchange agreement with SPIL to establish ASE Industrial Holding Co., Ltd. (”HoldCo”) and HoldCo will acquire all issued and outstanding shares of both ASE and SPIL in the way of share exchange. The share exchange will be conducted at an exchange ratio of 1 ordinary share of the Company for 0.5 ordinary share of HoldCo, and at NT$55 in cash per SPIL’s ordinary share, which has been adjusted to NT$51.2 after SPIL’s appropriation of earnings in 2016. The estimated cash consideration paid per SPIL’s ordinary share shall not be subject to adjustment if the aggregate amount of the cash dividends distributed by SPIL in 2017 is less than 85% of SPIL’s net profit for the year ended December 31, 2016. According to the share exchange agreement, the completion of share exchange transaction is subject to the satisfaction or waiver of all conditions precedent. Unless the Company and SPIL entering into another agreement, this share exchange agreement shall be terminated automatically if the aforementioned conditions precedent are not satisfied or to be waived on or before December 31, 2017. On November 24, 2017, the Ministry of Commerce of the People’s Republic of China announced that it has conditionally approved the proposed transaction. On December 14, 2017, the Company and SPIL entered into an addendum to the aforementioned joint share exchange agreement to amend the definition of Long Stop Date from December 31, 2017 to October 31, 2018. As of the date the consolidated financial statements were approved for issue by board of directors, the share exchange transaction has been approved both at the Company and SPIL’s special shareholders’ meetings, and will Due to the aforementioned share exchange agreement, treasury shares of the Company and the convertible bonds embedded with conversion option recognized as equity issued by the Company were affected as follows: 1) For the outstanding balance of the Bonds, except where the Bonds have been redeemed or repurchased and cancelled or converted by the holders by exercising their conversion rights before the share exchange record date, the holders of the Bonds may, after the Company obtains approval from all relevant competent authorities and after the share exchange record date, convert such outstanding balance into newly issued HoldCo common shares. The conversion shall be subject to applicable laws, the indenture of the Bonds and the share exchange ratio. As of December 31, 2017, the outstanding balance of the Bonds has been fully converted or redeemed. 2) Treasury shares purchased before the share exchange record date for the conversion of the Currency Linked Bonds will be exchanged to HoldCo’s ordinary shares, which will still be held by the Company, based on the agreed share exchange ratio. The conversion price of the Currency Linked Bonds shall also be adjusted in accordance with the agreed share exchange ratio in the joint share exchange agreement. 3) For the employee share options issued by the Company upon the approval from relevant competent authorities before the execution of the joint share exchange agreement, HoldCo will assume the Company’s obligations under the employee share options as of the share exchange record date. Except that the exercise price and amount shall be adjusted in accordance with the agreed share exchange ratio and that the shares subject to exercise shall be converted into HoldCo’s newly issued ordinary shares, all other terms and conditions for issuance will remain the same. The final execution arrangements shall be made by HoldCo in compliance with relevant laws and regulations and subject to the approval of relevant competent authorities.

Operating Segments Information

Operating Segments Information	12 Months Ended
	Dec. 31, 2017
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Operating Segments Information	41. OPERATING SEGMENTS INFORMATION The Group has the following reportable segments: Packaging, Testing, EMS and Estate. The Group packages bare semiconductors into finished semiconductors with enhanced electrical and thermal characteristics; provides testing services, including front-end engineering testing, wafer probing and final testing services; engages in the designing, assembling, manufacturing and sale of electronic components and telecommunications equipment motherboards, real estate business in development, sale and leasing. Information about other business activities and operating segments that are not reportable are combined and disclosed in “Others.” The Group engages in other activities such as substrate production. The accounting policies for segments are the same as those described in Note 4. The measurement basis for resources allocation and performance evaluation is based on profit before income tax. Segment information for the years ended December 31, 2015, 2016 and 2017 was as follows: a. Segment revenues and operation results Adjustments Packaging Testing EMS Estate Others and Eliminations Total NT$ NT$ NT$ NT$ NT$ NT$ NT$ For the year ended December 31, 2015 Revenue from external customers $ 116,607,314 $ 25,191,916 $ 138,242,100 $ 1,340 $ 3,259,866 $ - $ 283,302,536 Inter-segment revenues (Note) 9,454,671 191,608 58,451,996 - 7,659,282 (75,757,557 ) - Segment revenues 126,061,985 25,383,524 196,694,096 1,340 10,919,148 - 359,060,093 Interest income 53,235 12,536 149,385 54,876 13,445 (41,393 ) 242,084 Interest expense (1,520,118 ) (5,821 ) (147,792 ) - (636,448 ) 41,393 (2,268,786 ) Depreciation and amortization (18,946,460 ) (6,516,912 ) (2,738,722 ) (24,074 ) (1,292,496 ) - (29,518,664 ) Share of the profit of associates and joint ventures 126,265 - - - - - 126,265 Impairment loss (139,397 ) - (102,389 ) - (16,343 ) - (258,129 ) Segment profit before income tax 15,479,868 6,354,140 2,874,944 (172,521 ) 475,357 - 25,011,788 Expenditures for segment assets 19,691,068 4,754,481 2,917,939 143,436 773,897 - 28,280,821 December 31, 2015 Investments accounted for using the equity method 37,122,244 - - - - - 37,122,244 Segment assets 193,323,304 42,652,569 79,997,341 30,000,273 19,013,405 - 364,986,892 For the year ended December 31, 2016 Revenue from external customers 125,282,829 27,031,750 115,395,130 3,909,580 3,264,818 - 274,884,107 Inter-segment revenues (Note) 4,929,897 243,980 47,721,424 - 9,186,359 (62,081,660 ) - Segment revenues 130,212,726 27,275,730 163,116,554 3,909,580 12,451,177 - 336,965,767 Interest income 32,499 41,405 130,659 29,131 8,166 (11,793 ) 230,067 Interest expense (1,727,127 ) (5,980 ) (44,433 ) - (451,790 ) 11,793 (2,217,537 ) Depreciation and amortization (After retrospectively adjusted) (18,706,891 ) (6,566,936 ) (2,759,298 ) (55,271 ) (1,382,041 ) - (29,470,437 ) Share of the profit of associates and joint ventures (After retrospectively adjusted) 1,513,394 (9,484 ) - - - - 1,503,910 Impairment loss (974,095 ) (4,136 ) (1,886 ) - - - (980,117 ) Segment profit before income tax 13,921,640 7,226,531 4,626,263 1,546,326 647,945 - 27,968,705 Expenditures for segment assets 17,561,135 8,247,003 906,042 114,462 852,220 - 27,680,862 December 31, 2016 Investments accounted for using the equity method (After retrospectively adjusted) 49,597,195 227,495 - - - - 49,824,690 Segment assets (After retrospectively adjusted) 200,604,111 42,962,643 73,915,639 28,468,242 11,979,941 - 357,930,576 For the year ended December 31, 2017 Revenue from external customers 126,225,119 26,157,277 133,948,016 412,863 3,697,933 - 290,441,208 Inter-segment revenues (Note) 4,911,026 184,707 47,119,404 23,943 8,359,697 (60,598,777 ) - Segment revenues 131,136,145 26,341,984 181,067,420 436,806 12,057,630 - 351,039,985 Interest income 43,744 48,532 269,640 30,441 183,824 (269,310 ) 306,871 Interest expense (1,969,562 ) (11,920 ) - (62,714 ) - 269,310 (1,774,886 ) Depreciation and amortization (19,105,457 ) (6,476,743 ) (2,133,253 ) (180,792 ) (1,308,939 ) - (29,205,184 ) Share of the profit or loss of associates and joint ventures 568,291 (42,509 ) - - - - 525,782 Impairment loss (218,214 ) (72,798 ) - - (473,869 ) - (764,881 ) Segment profit before income tax 12,065,304 6,904,067 6,883,327 5,120,301 47,664 - 31,020,663 Expenditures for segment assets 17,769,612 4,507,097 850,235 169,559 381,179 - 23,677,682 December 31, 2017 Investments accounted for using the equity method 48,566,333 187,418 - - - - 48,753,751 Segment assets 195,503,889 43,383,691 81,588,691 33,080,694 10,365,307 - 363,922,272 Adjustments Packaging Testing EMS Estate Others and Eliminations Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) For the year ended December 31, 2017 Revenue from external customers $ 4,258,607 $ 882,499 $ 4,519,164 $ 13,929 $ 124,762 $ - $ 9,798,961 Inter-segment revenues (Note) 165,689 6,232 1,589,723 808 282,041 (2,044,493 ) - Segment revenues 4,424,296 888,731 6,108,887 14,737 406,803 - 11,843,454 Interest income 1,476 1,637 9,097 1,027 6,202 (9,086 ) 10,353 Interest expense (66,450 ) (402 ) - (2,116 ) - 9,086 (59,882 ) Depreciation and amortization (644,584 ) (218,514 ) (71,972 ) (6,100 ) (44,161 ) - (985,331 ) Share of the profit or loss of associates and joint ventures 19,173 (1,434 ) - - - - 17,739 Impairment loss (7,362 ) (2,456 ) - - (15,988 ) - (25,806 ) Segment profit before income tax 407,061 232,931 232,231 172,750 1,608 - 1,046,581 Expenditures for segment assets 599,515 152,061 28,685 5,721 12,860 - 798,842 December 31, 2017 Investments accounted for using the equity method $ 1,638,540 $ 6,323 $ - $ - $ - $ - $ 1,644,863 Segment assets 6,595,947 1,463,687 2,752,655 1,116,083 349,707 - 12,278,079 Note: Inter-segment revenues were eliminated upon consolidation. (Concluded) b. Revenue from major products and services For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Packaging service $ 116,607,314 $ 125,282,829 $ 126,225,119 $ 4,258,607 Testing service 25,191,916 27,031,750 26,157,277 882,499 Electronic components manufacturing service 138,242,100 115,395,130 133,948,016 4,519,164 Others 3,261,206 7,174,398 4,110,796 138,691 $ 283,302,536 $ 274,884,107 $ 290,441,208 $ 9,798,961 c. Geographical information Geographical information about revenue from external customers and noncurrent assets are reported based on the country where the external customers are headquartered and noncurrent assets are located, respectively. 1) Net revenues from external customers For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) United States $ 205,730,670 $ 180,745,837 $ 196,462,345 $ 6,628,284 Taiwan 32,631,149 38,868,679 35,413,647 1,194,792 Asia 22,885,128 29,896,304 30,201,332 1,018,938 Europe 20,577,069 23,275,732 26,445,240 892,215 Others 1,478,520 2,097,555 1,918,644 64,732 $ 283,302,536 $ 274,884,107 $ 290,441,208 $ 9,798,961 2) Noncurrent assets, excluding financial instruments, post-employment benefit assets and deferred tax assets December 31 2016 2017 NT$ NT$ US$ (Note 4) Taiwan $ 97,337,094 $ 93,350,839 $ 3,149,489 China 34,142,577 45,376,164 1,530,910 Others 26,935,370 25,025,498 844,315 $ 158,415,041 $ 163,752,501 $ 5,524,714 d. Major customers Except one customer from which the operating revenues generated from packaging and EMS segments was NT$88,311,697 thousand, NT$66,554,659 thousand and NT$83,873,393 thousand (US$2,829,737 thousand) in 2015, 2016 and 2017, respectively, the Group did not have other single customer to which the operating revenues exceeded 10% of operating revenues for the years ended December 31, 2015, 2016 and 2017.

Summary of Significant Accoun47

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Statement of Compliance	a. Statement of Compliance The consolidated financial statements have been prepared in accordance with IFRSs as issued by the IASB.
Basis of Preparation	b. Basis of Preparation The consolidated financial statements have been prepared on the historical cost basis except for certain financial instruments that are measured at fair value and net defined benefit liabilities which are measured at the present value of the defined benefit obligation less the fair value of plan assets. The fair value measurements are grouped into Levels 1 to 3 based on the degree to which the fair value measurement inputs are observable and the significance of the inputs to the fair value measurement in its entirety, which are described as follows: 1) Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; 2) Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for an asset or a liability, either directly (i.e. as prices) or indirectly (i.e. derived from prices); and 3) Level 3 inputs are unobservable inputs for an asset or a liability.
Classification of Current and Non-current Assets and Liabilities	c. Classification of Current and Non-current Assets and Liabilities Current assets include cash and cash equivalents and those assets held primarily for trading purposes or expected to be realized within twelve months after the balance sheet date, unless the asset is to be used for an exchange or to settle a liability, or otherwise remains restricted, at more than twelve months after the balance sheet date. Current liabilities are obligations incurred for trading purposes or to be settled within twelve months after the balance sheet date and liabilities that do not have an unconditional right to defer settlement for at least twelve months after the balance sheet date. Assets and liabilities that are not classified as current are classified as non-current. The Group engages in the construction business which has an operating cycle of over one year. The normal operating cycle applies when considering the classification of the Group’s construction-related assets and liabilities.
Basis of Consolidation	d. Basis of Consolidation 1) Principles for preparing consolidated financial statements The consolidated financial statements incorporate the financial statements of the Company and the entities controlled by the Company (i.e. its subsidiaries, including structured entities). Income and expenses of subsidiaries acquired or disposed of during the period are included in the consolidated statement of profit or loss and other comprehensive income from the effective dates of acquisitions up to the effective dates of disposals, as appropriate. When necessary, adjustments are made to the financial statements of subsidiaries to bring their accounting policies into line with those used by the Company. All intra-group transactions, balances, income and expenses are eliminated in full upon consolidation. Total comprehensive income of subsidiaries is attributed to the owners of the Company and to the non-controlling interests even if this results in the non-controlling interests having a deficit balance. Changes in the Group’s ownership interests in subsidiaries that do not result in the Group losing control over the subsidiaries are accounted for as equity transactions. The carrying amounts of the interests of the Group and the non-controlling interests are adjusted to reflect the changes in their relative interests in the subsidiaries. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity and attributed to the owners of the Company. When the Group loses control over a subsidiary, a gain or loss is recognized in profit or loss and is calculated as the difference between (i) the aggregate of the fair value of the consideration received and any investment retained in the former subsidiary at its fair value at the date when control is lost and (ii) the assets (including any goodwill) and liabilities and any non-controlling interests of the former subsidiary at their carrying amounts at the date when control is lost. The Group accounts for all amounts recognized in other comprehensive income in relation to that subsidiary on the same basis as would be required if the Group had directly disposed of the related assets or liabilities. 2) Subsidiaries included in consolidated financial statements were as follows: Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 A.S.E. Holding Limited Holding company Bermuda 100.0 100.0 J & R Holding Limited (“J&R Holding”) Holding company Bermuda 100.0 100.0 Innosource Limited Holding company British Virgin Islands 100.0 100.0 Omniquest Industrial Limited Holding company British Virgin Islands 100.0 100.0 ASE Marketing & Service Japan Co., Ltd. Engaged in marketing and sales services Japan 100.0 100.0 ASE Test, Inc. Engaged in the testing of semiconductors Kaohsiung, ROC 100.0 100.0 USI Inc. (“USIINC”) Engaged in investing activity Nantou, ROC 99.2 99.2 Luchu Development Corporation (“Luchu”) Engaged in the development of real estate properties Taipei, ROC 86.1 86.1 TLJ Intertech Inc. (“TLJ”) Engaged in information software services Taipei, ROC 60.0 60.0 Alto Enterprises Limited Holding company British Virgin Islands 100.0 100.0 Super Zone Holdings Limited Holding company Hong Kong 100.0 100.0 ASE (Kun Shan) Inc. Engaged in the packaging and testing of semiconductors Kun Shan, China 100.0 100.0 ASE Investment (Kun Shan) Limited Holding company Kun Shan, China 100.0 100.0 Advanced Semiconductor Engineering (China) Ltd. Will engage in the packaging and testing of semiconductors Shanghai, China 100.0 100.0 ASE Investment (Labuan) Inc. Holding company Malaysia 100.0 100.0 ASE Test Limited (“ASE Test”) Holding company Singapore 100.0 100.0 ASE (Korea) Inc. (“ASE Korea”) Engaged in the packaging and testing of semiconductors Korea 100.0 100.0 J&R Industrial Inc. Engaged in leasing equipment and investing activity Kaohsiung, ROC 100.0 100.0 ASE Japan Co., Ltd. (“ASE Japan”) Engaged in the packaging and testing of semiconductors Japan 100.0 100.0 ASE (U.S.) Inc. After-sales service and sales support U.S.A. 100.0 100.0 Global Advanced Packaging Technology Limited Holding company British Cayman Islands 100.0 100.0 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 ASE WeiHai Inc. Engaged in the packaging and testing of semiconductors Shandong, China 100.0 100.0 Suzhou ASEN Semiconductors Co., Ltd. (“ASEN”) Engaged in the packaging and testing of semiconductors Suzhou, China 60.0 60.0 Anstock Limited Engaged in financing activity British Cayman Islands 100.0 100.0 Anstock II Limited Engaged in financing activity British Cayman Islands 100.0 100.0 ASE Module (Shanghai) Inc. Absorbed by ASE (Shanghai) Inc. in February 2017 Shanghai, China 100.0 - ASE (Shanghai) Inc. Engaged in the production of substrates Shanghai, China 100.0 100.0 ASE Corporation Holding company British Cayman Islands 100.0 100.0 ASE Mauritius Inc. Holding company Mauritius 100.0 100.0 ASE Labuan Inc. Holding company Malaysia 100.0 100.0 Shanghai Ding Hui Real Estate Development Co., Ltd. Engaged in the development, construction and sale of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Qi Property Management Co., Ltd. Engaged in the management of real estate properties Shanghai, China 100.0 100.0 Advanced Semiconductor Engineering (HK) Limited Engaged in the trading of substrates Hong Kong 100.0 100.0 Shanghai Ding Wei Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Yu Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Fan Department Store Co., Ltd. Engaged in department store business Shanghai, China 100.0 100.0 Kun Shan Ding Yue Real Estate Development Co., Ltd. (“KSDY”) Engaged in the development, construction and leasing of real estate properties and was disposed of in June 2017 (Note 29) Kun Shan, China 100.0 - Kun Shan Ding Hong Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Kun Shan, China 100.0 100.0 Shanghai Ding Xu Property Management Co., Ltd. Engaged in the management of real estate properties, and was established in August 2017 Shanghai, China - 100.0 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 ASE Electronics Inc. Engaged in the production of substrates Kaohsiung, ROC 100.0 100.0 ASE Test Holdings, Ltd. Holding company British Cayman Islands 100.0 100.0 ASE Holdings (Singapore) Pte. Ltd. Holding company Singapore 100.0 100.0 ASE Singapore Pte. Ltd. Engaged in the packaging and testing of semiconductors Singapore 100.0 100.0 ISE Labs, Inc. Engaged in the testing of semiconductors U.S.A. 100.0 100.0 ASE Electronics (M) Sdn. Bhd. Engaged in the packaging and testing of semiconductors Malaysia 100.0 100.0 ASE Assembly & Test (Shanghai) Limited Engaged in the packaging and testing of semiconductors Shanghai, China 100.0 100.0 ASE Trading (Shanghai) Ltd. Engaged in trading activity Shanghai, China 100.0 100.0 Wuxi Tongzhi Microelectronics Co., Ltd. Engaged in the packaging and testing of semiconductors Wuxi, China 100.0 100.0 Huntington Holdings International Co., Ltd. Holding company British Virgin Islands 99.2 99.2 Unitech Holdings International Co., Ltd. Holding company British Virgin Islands 99.2 99.2 Real Tech Holdings Limited Holding company British Virgin Islands 99.2 99.2 Universal ABIT Holding Co., Ltd. In the process of liquidation British Cayman Islands 99.2 99.2 Rising Capital Investment Limited Holding company British Virgin Islands 99.2 99.2 Rise Accord Limited Holding company British Virgin Islands 99.2 99.2 Universal Scientific Industrial (Kunshan) Co., Ltd. Engaged in the manufacturing and sale of computer assistance system and related peripherals Kun Shan, China 99.2 99.2 USI Enterprise Limited (“USIE”) Engaged in the services of investment advisory and warehousing management Hong Kong 97.0 96.9 USISH Engaged in the designing, manufacturing and sale of electronic components Shanghai, China 75.9 75.8 Universal Global Technology Co., Limited Holding company Hong Kong 75.9 75.8 Universal Global Technology (Kunshan) Co., Ltd. Engaged in the designing and manufacturing of electronic components Kun Shan, China 75.9 75.8 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 Universal Global Technology (Shanghai) Co., Ltd. Engaged in the processing and sales of computer and communication peripherals as well as business in import and export of goods and technology Shanghai, China 75.9 75.8 Universal Global Electronics (Shanghai) Co., Ltd. Engaged in the sale of electronic components and telecommunications equipment Shanghai, China 75.9 75.8 Universal Global Industrial Co., Limited Engaged in manufacturing, trading and investing activity Hong Kong 75.9 75.8 Universal Global Scientific Industrial Co., Ltd. (“UGTW”) Engaged in the manufacturing of components of telecomm and cars and provision of related R&D services Nantou, ROC 75.9 75.8 USI America Inc. Engaged in the manufacturing and processing of motherboards and wireless network communication and provision of related technical service. U.S.A. 75.9 75.8 Universal Scientific Industrial De Mexico S.A. De C.V. Engaged in the assembling of motherboards and computer components Mexico 75.9 75.8 USI Japan Co., Ltd. Engaged in the manufacturing and sale of computer peripherals, integrated chip and other related accessories Japan 75.9 75.8 USI Electronics (Shenzhen) Co., Ltd. Engaged in the design, manufacturing and sale of motherboards and computer peripherals Shenzhen, China 75.9 75.8 Universal Scientific Industrial Co., Ltd. (“USI”) Engaged in the manufacturing, processing and sale of computers, computer peripherals and related accessories Nantou, ROC 75.2 75.5
Business Combinations	e. Business Combinations Acquisitions of businesses are accounted for using the acquisition method. Acquisition-related costs are generally recognized in profit or loss as they are incurred. Goodwill is measured as the excess of the sum of the consideration transferred, the amount of any non-controlling interests in the acquiree, and the fair value of the acquirer’s previously held equity interest in the acquiree (if any) over the net of the acquisition-date amounts of the identifiable assets acquired and the liabilities assumed. If, after re-assessment, the net of the acquisition-date amounts of the identifiable assets acquired and liabilities assumed exceeds the sum of the consideration transferred, the amount of any non-controlling interests in the acquiree and the fair value of the acquirer’s previously held interest in the acquiree (if any), the excess is recognized immediately in profit or loss as a bargain purchase gain. When a business combination is achieved in stages, the Group’s previously held equity interest in the acquiree is remeasured to its acquisition-date fair value and the resulting gain or loss, if any, is recognized in profit or loss. Amounts arising from interests in the acquiree prior to the acquisition date that have previously been recognized in other comprehensive income are recognized on the same basis as would be required if that interest were directly disposed of by the Group. If the initial accounting for a business combination is incomplete by the end of the reporting period in which the combination occurs, the Group reports provisional amounts for the items for which the accounting is incomplete. Those provisional amounts are adjusted retrospectively during the measurement period, 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. Business combination involving entities under common control is not accounted for by acquisition method but accounted for at the carrying amounts of the entities. Prior period comparative information in the financial statements is restated as if a business combination involving entities under common control had already occurred in that period.
Foreign Currencies	f. Foreign Currencies In preparing the financial statements of each individual group entity, transactions in currencies other than the entity’s functional currency (i.e. foreign currencies) are recognized at the rates of exchange prevailing at the dates of the transactions. At each balance sheet date, monetary items denominated in foreign currencies are retranslated at the rates prevailing at that date. Exchange differences on monetary items arising from settlement or translation are recognized in profit or loss in the period in which they arise. Non-monetary items measured at fair value that are denominated in foreign currencies are retranslated at the rates prevailing at the date when the fair value was determined. Exchange differences arising from the retranslation of non-monetary items are included in profit or loss for the period except for exchange differences arising from the retranslation of non-monetary items in respect of which gains and losses are recognized directly in other comprehensive income, in which cases, the exchange differences are also recognized directly in other comprehensive income. Non-monetary items that are measured at historical cost in a foreign currency are translated using the exchange rate at the date of the transaction, and are not retranslated. For the purposes of presenting the consolidated financial statements, the assets and liabilities of the Group’s foreign operations are translated into New Taiwan dollars using exchange rates prevailing at each balance sheet date. Income and expense items are translated at the average exchange rates for the period. The resulting currency translation differences are recognized in other comprehensive income and accumulated in equity attributed to the owners of the Company and non-controlling interests as appropriate. On the disposal of the Group’s entire interest in a foreign operation, or a disposal involving loss of control over a subsidiary that includes a foreign operation, all of the exchange differences accumulated in equity in respect of that operation attributable to the owners of the Company are reclassified to profit or loss. In relation to a partial disposal of a subsidiary that does not result in the Group losing control over the subsidiary, the proportionate share of accumulated exchange differences is re-attributed to the non-controlling interests of the subsidiary and is not recognized in profit or loss. For all other partial disposals, the proportionate share of the accumulated exchange differences recognized in other comprehensive income is reclassified to profit or loss.
Inventories and Inventories Related to Real Estate Business	g. Inventories and Inventories Related to Real Estate Business Inventories, including raw materials (materials received from customers for processing, mainly semiconductor wafers, are excluded from inventories as title and risk of loss remain with the customers), supplies, work in process, finished goods, and materials and supplies in transit are stated at the lower of cost or net realizable value. Inventory write-downs are made by item, except for those that may be appropriate to group items of similar or related inventories. Net realizable value is the estimated selling prices of inventories less all estimated costs of completion and estimated costs necessary to make the sale. Raw materials and supplies are recorded at moving average cost while work in process and finished goods are recorded at standard cost. Inventories related to real estate business include land and buildings held for sale, land held for construction and construction in progress. Land held for development is recorded as land held for construction upon obtaining the title of ownership. Prior to the completion, the borrowing costs directly attributable to construction in progress are capitalized as part of the cost of the asset. Construction in progress is transferred to land and buildings held for sale upon completion. Land and buildings held for sale, construction in progress and land held for construction are stated at the lower of cost or net realizable value and related write-downs are made by item. The amounts received in advance for real estate properties are first recorded as advance receipts and then recognized as revenue when the construction is completed and the title and significant risk of the real estate properties are transferred to customers. Cost of sales of land and buildings held for sale are recognized based on the ratio of property sold to the total property developed.
Investments in associates and joint ventures	h. Investments in associates and joint ventures An associate is an entity over which the Group has significant influence and that is neither a subsidiary nor an interest in a joint venture. Joint venture is a joint arrangement whereby the Group and other parties that have joint control of the arrangement have rights to the net assets of the arrangement. Under the equity method, investments in an associate and a joint venture are initially recognized at cost and adjusted thereafter to recognize the Group’s share of the profit or loss and other comprehensive income of the associate and joint venture. The Group also recognizes the changes in the Group’s share of equity of associates and joint venture. Any excess of the cost of acquisition over the Group’s share of the fair value of the net identifiable assets and liabilities of an associate or a joint venture at the date of acquisition is recognized as goodwill, which is included within the carrying amount of the investment and is not amortized. Gains and losses resulting from upstream, downstream and sidestream transactions between the Group (including its subsidiaries) and its associates or joint ventures are recognized in the Group’s consolidated financial statements only to the extent of interests in the associates or joint ventures that are not related to the Group.
Property, Plant and Equipment	i. Property, Plant and Equipment Except for land which is stated at cost, property, plant and equipment are stated at cost less accumulated depreciation and accumulated impairment. Properties in the course of construction are carried at cost, less any recognized impairment loss. Cost includes professional fees and borrowing costs eligible for capitalization. Such assets are depreciated and classified to the appropriate categories of property, plant and equipment when completed and ready for intended use. Freehold land is not depreciated. Depreciation of property, plant and equipment is recognized using the straight-line method. Each significant part is depreciated separately. If the lease term is shorter than the assets’ useful lives, such assets are depreciated over the lease term. The estimated useful lives, residual values and depreciation method are reviewed at each balance sheet date, with the effect of any changes in estimate accounted for on a prospective basis. On derecognition of an item of property, plant and equipment, the difference between the sales proceeds and the carrying amount of the asset is recognized in profit or loss.
Investment Properties	j. Investment properties Investment properties are properties held to earn rentals and/or for capital appreciation (including property under construction for such purposes). Investment properties are measured initially at cost, including transaction costs. Subsequent to initial recognition, investment properties are measured at cost less accumulated depreciation and accumulated impairment loss. Depreciation is recognized using the straight-line method. Investment properties under construction are stated at cost less accumulated depreciation and accumulated impairment loss. Cost includes professional fees and, borrowing costs eligible for capitalization. Depreciation of these assets commences when the assets are ready for their intended use. On derecognition of an investment property, the difference between the net disposal proceeds and the carrying amount of the asset is included in profit or loss.
Goodwill	k. Goodwill Goodwill arising from an acquisition of a business is carried at cost as established at the date of acquisition of the business less accumulated impairment loss. For the purposes of impairment testing, goodwill is allocated to each of the Group’s cash-generating units or groups of cash-generating units (referred to as “cash-generating units”) that is expected to benefit from the synergies of the combination. A cash-generating unit to which goodwill has been allocated is tested for impairment annually, or more frequently when there is an indication that the unit may be impaired, by comparing its carrying amount, including the attributed goodwill, with its recoverable amount. However, if the goodwill allocated to a cash-generating unit was acquired in a business combination during the current annual period, that unit shall be tested for impairment before the end of the current annual period. If the recoverable amount of the cash-generating unit is less than its carrying amount, the impairment loss is allocated first to reduce the carrying amount of any goodwill allocated to the unit and then pro rata to the other assets of the unit based on the carrying amount of each asset in the unit. Any impairment loss is recognized directly in profit or loss. An impairment loss recognized for goodwill is not reversed in subsequent periods.
Other Intangible Assets	l. Other Intangible Assets Other intangible assets with finite useful lives acquired separately are initially measured at cost and subsequently measured at cost less accumulated amortization and accumulated impairment loss. Other intangible assets are amortized based on the pattern in which the economic benefits are consumed or using the straight-line method over their estimated useful lives. The estimated useful lives, residual values, and amortization methods are reviewed at each balance sheet date, with the effect of any changes in estimate being accounted for on a prospective basis. Other intangible assets acquired in a business combination and 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, they are measured on the same basis as intangible assets that are acquired separately. On derecognition of an intangible asset, the difference between the net disposal proceeds and the carrying amount of the asset are recognized in profit or loss.
Impairment of Tangible and Intangible Assets Other than Goodwill	m. Impairment of Tangible and Intangible Assets Other than Goodwill At each balance sheet date, the Group reviews the carrying amounts of its tangible and intangible assets, excluding goodwill, 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. When it is not possible to estimate the recoverable amount of an individual asset, the Group estimates the recoverable amount of the cash-generating unit to which the asset belongs. Corporate assets are allocated to the individual cash-generating units on a reasonable and consistent basis of allocation. The recoverable amount is the higher of fair value less costs to sell and value in use. If the recoverable amount of an asset or cash-generating unit is estimated to be less than its carrying amount, the carrying amount of the asset or cash-generating unit is reduced to its recoverable amount, with the resulting impairment loss recognized in profit or loss. When an impairment loss is subsequently reversed, the carrying amount of the asset or cash-generating unit is increased to the revised estimate of its recoverable amount, but only to the extent of 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.
Financial Instruments	n. Financial Instruments Financial assets and financial liabilities are recognized when a group entity becomes a party to the contractual provisions of the instruments. Financial assets and financial liabilities are initially measured at fair value. Transaction costs that are directly attributable to the acquisition or issue of financial assets and financial liabilities (other than financial assets and financial liabilities at fair value through profit or loss) are added to or deducted from the fair value of the financial assets or financial liabilities, as appropriate, on initial recognition. Transaction costs directly attributable to the acquisition of financial assets or financial liabilities at fair value through profit or loss are recognized immediately in profit or loss. 1) Financial assets All regular way purchases or sales of financial assets are recognized or derecognized on a settlement date basis. a) Measurement category The classification of financial assets held by the Group depends on the nature and purpose of the financial assets and is determined at the time of initial recognition. i Financial assets at fair value through profit or loss (“FVTPL”) Financial assets are classified as at FVTPL when the financial assets are either held for trading or they are designated as at FVTPL. A financial asset other than a financial asset 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 asset forms part of a group of financial assets or financial liabilities or both, which is managed and has performance evaluated on a fair value basis, in accordance with the Group’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or • The contract contains one or more embedded derivatives so that the entire hybrid (combined) contract can be designated as at FVTPL. Financial assets at FVTPL are stated at fair value with any gains or losses arising on remeasurement recognized in profit or loss. The net gain or loss recognized in profit or loss incorporates any dividend or interest earned on the financial asset. Fair value is determined in the manner described in Note 34. ii Available-for-sale financial assets Available-for-sale financial assets are non-derivatives that are either designated as available-for-sale or are not classified as (a) loans and receivables, (b) held-to-maturity investments or (c) financial assets at fair value through profit or loss. Available-for-sale financial assets are stated at fair value at each balance sheet date. Changes in the carrying amount of available-for-sale monetary financial assets relating to changes in foreign currency rates, interest income calculated using the effective interest method and dividends on available-for-sale equity investments are recognized in profit or loss. Other changes in the carrying amount of available-for-sale financial assets are recognized in other comprehensive income and accumulated under the heading of unrealized gain (loss) on available-for-sale financial assets. When the investment is disposed of or is determined to be impaired, the cumulative gain or loss previously accumulated in the unrealized gain (loss) on available-for-sale financial assets is reclassified to profit or loss. Dividends on available-for-sale equity instruments are recognized in profit or loss when the Group’s right to receive the dividends is established. iii Loans and receivables Loans and receivables including cash and cash equivalents, trade receivables, other receivables and other financial assets are measured at amortized cost using the effective interest method, less any impairment. Interest income is recognized by applying the effective interest rate, except for short-term receivables when the effect of discounting is immaterial. Cash equivalents are short-term, highly liquid investments that are readily convertible to known amounts of cash and which are subject to an insignificant risk of change in value. b) Impairment of financial assets Financial assets, other than those at FVTPL, are assessed for indicators of impairment at each balance sheet date. 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 assets, the estimated future cash flows of the investments have been affected. For financial assets carried at amortized cost, such as trade receivables and other receivables, assets that are assessed not to be impaired individually are, further, assessed for impairment on a collective basis. The Group assesses the collectability of receivables based on the Group’s past experience of collecting payments and observable changes that correlate with default on receivables. For financial assets carried at amortized cost, the amount of the impairment loss recognized is the difference between the assets’ carrying amounts and the present value of estimated future cash flows, discounted at the financial assets’ original effective interest rates. If, in a subsequent period, the amount of the impairment loss decreases and the decreases can be objectively related to an event occurring after the impairment loss recognized, the previously recognized impairment loss is reversed either directly or by adjusting an allowance account through profit or loss. The reversal shall not result in carrying amounts of financial assets that exceed what the amortized cost would have been at the date the impairment is reversed. For any available-for-sale equity investments, a significant or prolonged decline in the fair value of the security below its cost is considered to be objective evidence of impairment. When an available-for-sale financial asset is considered to be impaired, cumulative gains or losses previously recognized in other comprehensive income are reclassified to profit or loss in the period. In respect of available-for-sale equity securities, impairment loss previously recognized in profit or loss is not reversed through profit or loss. Any increase in fair value subsequent to an impairment loss is recognized in other comprehensive income. In respect of available-for-sale debt securities, impairment loss is subsequently reversed through profit or loss if an increase in the fair value of the investment can be objectively related to an event occurring after the recognition of the impairment loss. 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 profit or loss except for uncollectible trade receivables that are written off against the allowance account. c) Derecognition of financial assets The Group derecognizes a financial asset only when the contractual rights to the cash flows from the asset expire, or when it transfers the financial asset and substantially all the risks and rewards of ownership of the asset to another entity. On derecognition of a financial asset in its entirety, the difference between the asset’s carrying amount and the sum of the consideration received and receivable and the cumulative gain or loss that had been recognized in other comprehensive income and accumulated in equity is recognized in profit or loss. 2) Equity instruments Debt and equity instruments issued by a group entity are classified as either financial liabilities or as equity in accordance with the substance of the contractual arrangements and the definitions of a financial liability and an equity instrument. Equity instruments issued by a group entity are recognized at the proceeds received, net of direct issue costs. Repurchase of the Company’s own equity instruments is recognized in and deducted directly from equity. No gain or loss is recognized in profit or loss on the purchase, sale, issue or cancellation of the Company’s own equity instruments. 3) Financial liabilities Financial liabilities are measured either at amortized cost using the effective interest method or at FVTPL. Financial liabilities measured at FVTPL are held for trading. Financial liabilities at FVTPL are stated at fair value, with any gain or loss arising on remeasurement recognized in profit or loss. The net gain or loss recognized in profit or loss incorporates any interest or dividend paid on the financial liability. Fair value is determined in the manner described in Note 34. The Group derecognizes financial liabilities when, and only when, the Group’s obligations are discharged, cancelled or they expire. The difference between the carrying amount of the financial liability derecognized and the consideration paid and payable is recognized in profit or loss. 4) Derivative financial instruments Derivatives are initially recognized at fair value at the date the derivative contracts are entered into and are subsequently remeasured to their fair value at each balance sheet date. The resulting gain or loss is recognized in profit or loss immediately unless the derivative is designated and effective as a hedging instrument, in which event the timing of the recognition in profit or loss depends on the nature of the hedge relationship. When the fair value of derivative financial instruments is positive, the derivative is recognized as a financial asset; when the fair value of derivative financial instruments is negative, the derivative is recognized as financial liabilities. Derivatives embedded in non-derivative host contracts are treated as separate derivatives when they meet the definition of a derivative, their risks and characteristics are not closely related to those of the host contracts and the contracts are not measured at FVTPL. 5) Convertible bonds a) Convertible bonds contain conversion option classified as an equity The component parts of compound instruments (convertible bonds) issued by the Group are classified separately as financial liabilities and equity in accordance with the substance of the contractual arrangements and the definitions of a financial liability and an equity instrument. On initial recognition, the fair value of the liability component is estimated using the prevailing market interest rate for similar non-convertible instruments. This amount is recorded as a liability on an amortized cost basis using the effective interest method until extinguished upon conversion or the instrument’s maturity date. Any embedded derivative liability is measured at fair value. The conversion option classified as equity is determined by deducting the amount of the liability component from the fair value of the compound instrument as a whole. This is recognized and included in equity, net of income tax effects, and is not subsequently remeasured. In addition, the conversion option classified as equity will remain in equity until the conversion option is exercised, in which case, the balance recognized in equity will be transferred to capital surplus - share premium. When the conversion option remains unexercised at maturity, the balance recognized in equity will be transferred to capital surplus - share premium. Transaction costs that relate to the issue of the convertible bonds are allocated to the liability and equity components in proportion to the allocation of the gross proceeds. Transaction costs relating to the equity component are recognized directly in equity. Transaction costs relating to the liability component are included in the carrying amount of the liability component. b) Convertible bonds contain conversion option classified as a liability The conversion options component of the convertible bonds issued by the Group that will be settled other than by the exchange of a fixed amount of cash or other financial asset for a fixed number of the Group’s own equity instruments is classified as derivative financial liabilities. On initial recognition, the derivative financial liabilities component of the convertible bonds is recognized at fair value, and the initial carrying amount of the component of non-derivative financial liabilities is determined by deducting the amount of derivative financial liabilities from the fair value of the hybrid instrument as a whole. In subsequent periods, the non-derivative financial liabilities component of the convertible bonds is measured at amortized cost using the effective interest method. The derivative financial liabilities component is measured at fair value and the changes in fair value are recognized in profit or loss. Transaction costs that relate to the issue of the convertible bonds are allocated to the derivative financial liabilities component and the non-derivative financial liabilities component in proportion to their relative fair values. Transaction costs relating to the derivative financial liabilities component are recognized immediately in profit or loss. Transaction costs relating to the non-derivative financial liabilities component are included in the carrying amount of the liability component.
Hedge Accounting	o. Hedge Accounting The Group designates certain hedging instruments as fair value hedges. Changes in the fair value of derivatives that are designated and qualify as fair value hedges are recognized in profit 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 change in the fair value of the hedging instrument and the change in the hedged item attributable to the hedged risk are recognized in profit or loss in the line item relating to the hedged item. Hedge accounting is discontinued prospectively when the Group revokes the designated hedging relationship; when the hedging instrument expires or is sold, terminated, or exercised; or when the hedging instrument no longer meets the criteria for hedge accounting.
Revenue Recognition	p. Revenue Recognition Revenue is measured at the fair value of the consideration received or receivable take into account of estimated customer returns, rebates and other similar allowances. 1) Sale of goods and real estate properties Revenue from the sale of goods and real estate properties is recognized when the goods and real estate properties are delivered and titles have passed, at the time all the following conditions are satisfied: • The Group has transferred to the buyer the significant risks and rewards of ownership of the goods and real estate properties; • The Group retains neither continuing managerial involvement to the degree usually associated with ownership nor effective control over the goods and real estate properties sold; • The amount of revenue can be reliably measured; • It is probable that the economic benefits associated with the transaction will flow to the Group; and • The costs incurred or to be incurred in respect of the transaction can be reliably measured. 2) Rendering of services Service income is recognized when services are rendered. 3) Dividend and interest income Dividend income from investments and interest income from financial assets are recognized when they are probable that the economic benefits will flow to the Group and the amount of income can be reliably measured. Interest income is accrued on a time basis, by reference to the principal outstanding and at the effective interest rate applicable.
Leasing	q. Leasing 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. The Group as lessor Rental income from operating leases is recognized on a straight-line basis over the term of the relevant lease. The Group as lessee Assets held under finance leases are initially recognized as assets of the Group 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 consolidated balance sheets as a finance lease obligation. Operating lease payments are recognized as expenses on a straight-line basis over the lease term.
Borrowing Costs	r. Borrowing Costs Borrowing costs directly attributable to the acquisition, construction or production of qualifying assets are added to the cost of those assets, until such time as the assets are substantially ready for their 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. Other than stated above, all other borrowing costs are recognized in profit or loss in the period in which they are incurred.
Government grants	s. Government grants Government grants are not recognized until there is reasonable assurance that the Group will comply with the conditions attaching to them and that the grants will be received. Government grants are recognized in profit or loss on a systematic basis over the periods in which the Group recognizes as expenses the related costs for which the grants are intended to compensate. Specifically, government grants whose primary condition is that the Group should purchase, construct or otherwise acquire non-current assets are recognized as deferred revenue in the consolidated financial statements and transferred to profit or loss on a systematic and rational basis over the useful lives of the related assets. Government grants that are receivable as compensation for expenses or losses already incurred or for the purpose of giving immediate financial support to the Group with no future related costs are recognized in profit or loss in the period in which they become receivable.
Retirement Benefit Costs	t. Retirement Benefit Costs Payments to defined contribution retirement benefit plans are recognized as expenses when employees have rendered services entitling them to the contributions. Defined benefit costs (including service cost, net interest and remeasurement) under the defined benefit retirement benefit plans are determined using the projected unit credit method. Service cost (including current service cost and past service cost) and net interest on the net defined benefit liability (asset) are recognized as employee benefits expense in the period they occur. Remeasurement, comprising actuarial gains and losses and the return on plan assets (excluding interest), is recognized in other comprehensive income in the period in which they occur. Remeasurement recognized in other comprehensive income is reflected immediately in retained earnings and will not be reclassified to profit or loss. Net defined benefit liability (asset) represents the actual deficit (surplus) in the Group’s defined benefit plan. Any surplus resulting from this calculation is limited to the present value of any refunds from the plans or reductions in future contributions to the plans.
Employee share options	u. Employee share options Employee share options granted to employees are measured at the fair value at the grant date. The fair value determined at the grant date is expensed on a straight-line basis over the vesting period, based on the Group’s best estimate of the number of options that are expected to ultimately vest, with a corresponding increase in capital surplus - employee share options and non-controlling interests. It is recognized as an expense in full at the grant date if vesting immediately. At each balance sheet date, the Group reviews its estimate of the number of employee share options expected to vest. The impact of the revision of the original estimates is recognized in profit or loss such that the cumulative expense reflects the revised estimate, with a corresponding adjustment to the capital surplus - employee share options and non-controlling interests.
Taxation	v. Taxation Income tax expense represents the sum of the tax currently payable and deferred tax. 1) Current tax Income tax on unappropriated earnings (excluding earnings from foreign consolidated subsidiaries) at a rate of 10% is expensed in the year the earnings arise and adjusted to the extent that distributions are approved by the shareholders in the following year. Adjustments of prior years’ tax liabilities are added to or deducted from the current year’s tax provision. 2) Deferred tax Deferred tax is recognized on temporary differences between the carrying amounts of assets and liabilities in the consolidated financial statements and the corresponding tax bases used in the computation of taxable profit. Deferred tax liabilities are generally recognized for all taxable temporary differences. Deferred tax assets are generally recognized for all deductible temporary differences, unused loss carry-forward and unused tax credits for purchases of machinery and equipment to the extent that it is probable that taxable profits will be available against which those deductible temporary differences can be utilized. Deferred tax liabilities are recognized for taxable temporary differences associated with investments in subsidiaries except where the Group is able to control the reversal of the temporary differences and it is probable that the temporary differences will not reverse in the foreseeable future. The carrying amounts of deferred tax assets is reviewed at each balance sheet date and reduced to the extent that it is no longer probable that sufficient taxable profits will be available to allow all or part of deferred tax assets to be utilized. A previously unrecognized deferred tax asset is also reviewed at each balance sheet date and recognized to the extent that it has become probable that future taxable profit will allow the deferred tax asset to be recovered. Deferred tax assets and liabilities are measured at the tax rates that are expected to apply in the period in which assets are realized or the liabilities are settled. The measurement of deferred tax assets and liabilities reflects the tax consequences that would follow from the manner in which the Group expects, at the balance sheet date, to recover or settle the carrying amounts of its assets and liabilities. 3) Current and deferred tax for the year Current and deferred tax are recognized in profit 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.
U.S. Dollar Amounts	w. U.S. Dollar Amounts A translation of the consolidated financial statements into U.S. dollars is included solely for the convenience of the readers, and has been translated from New Taiwan dollar (NT$) at the exchange rate as set forth in the statistical release by the U.S. Federal Reserve Board of the United States, which was NT$29.64 to US$1.00 as of December 31, 2017. The translation should not be construed as a representation that the NT$ amounts have been, could have been, or could in the future be, converted into U.S. dollars at this or any other rate of exchange.

Summary of Significant Accoun48

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Subsidiaries	2) Subsidiaries included in consolidated financial statements were as follows: Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 A.S.E. Holding Limited Holding company Bermuda 100.0 100.0 J & R Holding Limited (“J&R Holding”) Holding company Bermuda 100.0 100.0 Innosource Limited Holding company British Virgin Islands 100.0 100.0 Omniquest Industrial Limited Holding company British Virgin Islands 100.0 100.0 ASE Marketing & Service Japan Co., Ltd. Engaged in marketing and sales services Japan 100.0 100.0 ASE Test, Inc. Engaged in the testing of semiconductors Kaohsiung, ROC 100.0 100.0 USI Inc. (“USIINC”) Engaged in investing activity Nantou, ROC 99.2 99.2 Luchu Development Corporation (“Luchu”) Engaged in the development of real estate properties Taipei, ROC 86.1 86.1 TLJ Intertech Inc. (“TLJ”) Engaged in information software services Taipei, ROC 60.0 60.0 Alto Enterprises Limited Holding company British Virgin Islands 100.0 100.0 Super Zone Holdings Limited Holding company Hong Kong 100.0 100.0 ASE (Kun Shan) Inc. Engaged in the packaging and testing of semiconductors Kun Shan, China 100.0 100.0 ASE Investment (Kun Shan) Limited Holding company Kun Shan, China 100.0 100.0 Advanced Semiconductor Engineering (China) Ltd. Will engage in the packaging and testing of semiconductors Shanghai, China 100.0 100.0 ASE Investment (Labuan) Inc. Holding company Malaysia 100.0 100.0 ASE Test Limited (“ASE Test”) Holding company Singapore 100.0 100.0 ASE (Korea) Inc. (“ASE Korea”) Engaged in the packaging and testing of semiconductors Korea 100.0 100.0 J&R Industrial Inc. Engaged in leasing equipment and investing activity Kaohsiung, ROC 100.0 100.0 ASE Japan Co., Ltd. (“ASE Japan”) Engaged in the packaging and testing of semiconductors Japan 100.0 100.0 ASE (U.S.) Inc. After-sales service and sales support U.S.A. 100.0 100.0 Global Advanced Packaging Technology Limited Holding company British Cayman Islands 100.0 100.0 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 ASE WeiHai Inc. Engaged in the packaging and testing of semiconductors Shandong, China 100.0 100.0 Suzhou ASEN Semiconductors Co., Ltd. (“ASEN”) Engaged in the packaging and testing of semiconductors Suzhou, China 60.0 60.0 Anstock Limited Engaged in financing activity British Cayman Islands 100.0 100.0 Anstock II Limited Engaged in financing activity British Cayman Islands 100.0 100.0 ASE Module (Shanghai) Inc. Absorbed by ASE (Shanghai) Inc. in February 2017 Shanghai, China 100.0 - ASE (Shanghai) Inc. Engaged in the production of substrates Shanghai, China 100.0 100.0 ASE Corporation Holding company British Cayman Islands 100.0 100.0 ASE Mauritius Inc. Holding company Mauritius 100.0 100.0 ASE Labuan Inc. Holding company Malaysia 100.0 100.0 Shanghai Ding Hui Real Estate Development Co., Ltd. Engaged in the development, construction and sale of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Qi Property Management Co., Ltd. Engaged in the management of real estate properties Shanghai, China 100.0 100.0 Advanced Semiconductor Engineering (HK) Limited Engaged in the trading of substrates Hong Kong 100.0 100.0 Shanghai Ding Wei Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Yu Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Shanghai, China 100.0 100.0 Shanghai Ding Fan Department Store Co., Ltd. Engaged in department store business Shanghai, China 100.0 100.0 Kun Shan Ding Yue Real Estate Development Co., Ltd. (“KSDY”) Engaged in the development, construction and leasing of real estate properties and was disposed of in June 2017 (Note 29) Kun Shan, China 100.0 - Kun Shan Ding Hong Real Estate Development Co., Ltd. Engaged in the development, construction and leasing of real estate properties Kun Shan, China 100.0 100.0 Shanghai Ding Xu Property Management Co., Ltd. Engaged in the management of real estate properties, and was established in August 2017 Shanghai, China - 100.0 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 ASE Electronics Inc. Engaged in the production of substrates Kaohsiung, ROC 100.0 100.0 ASE Test Holdings, Ltd. Holding company British Cayman Islands 100.0 100.0 ASE Holdings (Singapore) Pte. Ltd. Holding company Singapore 100.0 100.0 ASE Singapore Pte. Ltd. Engaged in the packaging and testing of semiconductors Singapore 100.0 100.0 ISE Labs, Inc. Engaged in the testing of semiconductors U.S.A. 100.0 100.0 ASE Electronics (M) Sdn. Bhd. Engaged in the packaging and testing of semiconductors Malaysia 100.0 100.0 ASE Assembly & Test (Shanghai) Limited Engaged in the packaging and testing of semiconductors Shanghai, China 100.0 100.0 ASE Trading (Shanghai) Ltd. Engaged in trading activity Shanghai, China 100.0 100.0 Wuxi Tongzhi Microelectronics Co., Ltd. Engaged in the packaging and testing of semiconductors Wuxi, China 100.0 100.0 Huntington Holdings International Co., Ltd. Holding company British Virgin Islands 99.2 99.2 Unitech Holdings International Co., Ltd. Holding company British Virgin Islands 99.2 99.2 Real Tech Holdings Limited Holding company British Virgin Islands 99.2 99.2 Universal ABIT Holding Co., Ltd. In the process of liquidation British Cayman Islands 99.2 99.2 Rising Capital Investment Limited Holding company British Virgin Islands 99.2 99.2 Rise Accord Limited Holding company British Virgin Islands 99.2 99.2 Universal Scientific Industrial (Kunshan) Co., Ltd. Engaged in the manufacturing and sale of computer assistance system and related peripherals Kun Shan, China 99.2 99.2 USI Enterprise Limited (“USIE”) Engaged in the services of investment advisory and warehousing management Hong Kong 97.0 96.9 USISH Engaged in the designing, manufacturing and sale of electronic components Shanghai, China 75.9 75.8 Universal Global Technology Co., Limited Holding company Hong Kong 75.9 75.8 Universal Global Technology (Kunshan) Co., Ltd. Engaged in the designing and manufacturing of electronic components Kun Shan, China 75.9 75.8 (Continued) Establishment and Percentage of Ownership (%) December 31 Name of Investee Main Businesses Operating Location 2016 2017 Universal Global Technology (Shanghai) Co., Ltd. Engaged in the processing and sales of computer and communication peripherals as well as business in import and export of goods and technology Shanghai, China 75.9 75.8 Universal Global Electronics (Shanghai) Co., Ltd. Engaged in the sale of electronic components and telecommunications equipment Shanghai, China 75.9 75.8 Universal Global Industrial Co., Limited Engaged in manufacturing, trading and investing activity Hong Kong 75.9 75.8 Universal Global Scientific Industrial Co., Ltd. (“UGTW”) Engaged in the manufacturing of components of telecomm and cars and provision of related R&D services Nantou, ROC 75.9 75.8 USI America Inc. Engaged in the manufacturing and processing of motherboards and wireless network communication and provision of related technical service. U.S.A. 75.9 75.8 Universal Scientific Industrial De Mexico S.A. De C.V. Engaged in the assembling of motherboards and computer components Mexico 75.9 75.8 USI Japan Co., Ltd. Engaged in the manufacturing and sale of computer peripherals, integrated chip and other related accessories Japan 75.9 75.8 USI Electronics (Shenzhen) Co., Ltd. Engaged in the design, manufacturing and sale of motherboards and computer peripherals Shenzhen, China 75.9 75.8 Universal Scientific Industrial Co., Ltd. (“USI”) Engaged in the manufacturing, processing and sale of computers, computer peripherals and related accessories Nantou, ROC 75.2 75.5

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Cash and Cash Equivalents	December 31 2016 2017 NT$ NT$ US$ (Note 4) Cash on hand $ 6,856 $ 8,404 $ 284 Checking accounts and demand deposits 28,823,763 39,697,319 1,339,316 Cash equivalents 9,561,905 6,372,343 214,991 $ 38,392,524 $ 46,078,066 $ 1,554,591

Financial Instruments at Fair50

Financial Instruments at Fair Value Through Profit or Loss (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Financial Instruments at Fair Value Through Profit or Loss	December 31 2016 2017 NT$ NT$ US$ (Note 4) Financial assets designated as at FVTPL Private-placement convertible bonds $ 100,583 $ 100,496 $ 3,391 Financial assets held for trading Quoted shares $ 1,855,073 $ 4,410,732 $ 148,810 Open-end mutual funds 584,945 589,976 19,905 Forward exchange contracts 66,872 61,325 2,069 Swap contracts 462,339 60,538 2,042 2,969,229 5,122,571 172,826 $ 3,069,812 $ 5,223,067 $ 176,217 Financial liabilities held for trading Swap contracts $ 422,934 $ 652,107 $ 22,001 Forward exchange contracts 108,912 25,323 854 Conversion option, redemption option and put option of convertible bonds (Note 20) 1,213,890 - - Foreign currency option contracts 17,924 - - $ 1,763,660 $ 677,430 $ 22,855
Summary of Outstanding Contracts Not Accounted for Hedge Accounting	At each balance sheet date, the outstanding swap contracts not accounted for hedge accounting were as follows: Notional Amount Currency Maturity Period (In Thousands) December 31, 2016 Sell NT$/Buy US$ 2017.01-2017.12 NT$59,797,499/US$1,871,000 Sell US$/Buy CNY 2017.03 US$49,904/CNY349,800 Sell US$/Buy JPY 2017.02 US$77,153/JPY8,600,000 Sell US$/Buy NT$ 2017.01 US$61,000/NT$1,958,908 December 31, 2017 Sell NT$/Buy US$ 2018.01-2018.12 NT$53,136,302/US$1,782,400 Sell US$/Buy CNY 2018.01 US$52,948/CNY349,800 Sell US$/Buy JPY 2018.02-2018.03 US$70,324/JPY7,870,000 Sell US$/Buy NT$ 2018.01 US$217,300/NT$6,505,767 At each balance sheet date, the outstanding forward exchange contracts not accounted for hedge accounting were as follow: Notional Amount Currency Maturity Period (In Thousands) December 31, 2016 Sell NT$/Buy US$ 2017.01-2017.02 NT$2,842,330/US$90,000 Sell US$/Buy CNY 2017.01-2017.02 US$70,000/CNY484,805 Sell US$/Buy JPY 2017.01-2017.02 US$43,877/JPY5,063,820 Sell US$/Buy KRW 2017.01 US$35,000/KRW41,012,700 Sell US$/Buy MYR 2017.01-2017.02 US$19,000/MYR84,544 Sell US$/Buy NT$ 2017.01-2017.03 US$190,000/NT$6,099,400 Sell US$/Buy SGD 2017.01-2017.03 US$12,900/SGD18,080 Sell US$/Buy EUR 2017.01 US$281/EUR270 December 31, 2017 Sell NT$/Buy US$ 2018.01 NT$2,389,620/US$80,000 Sell US$/Buy CNY 2018.01-2018.04 US$125,000/CNY828,858 Sell US$/Buy EUR 2018.01 US$10,674/EUR9,000 Sell US$/Buy JPY 2018.01-2018.02 US$45,517/JPY5,111,101 Sell US$/Buy MYR 2018.01-2018.03 US$15,000/MYR61,859 Sell US$/Buy NT$ 2018.01 US$1,000/NT$30,142 Sell US$/Buy SGD 2018.01-2018.02 US$11,300/SGD15,305 At each balance sheet date, the outstanding foreign currency option contracts not accounted for hedge accounting were as follows: Notional Amount Currency Maturity Period (In Thousands) December 31, 2016 Buy US$ Call/CNY Put 2017.08 (Note) US$2,000/CNY13,800 Sell US$ Put/CNY Call 2017.08 (Note) US$1,000/CNY6,900 Note: The contracts will be settled once a month and the counterparty has the right to early terminate the contracts, or the contracts will be early terminated or both parties will have no obligation to settle the contracts when the specific criteria are met.

Available-for-sale Financial 51

Available-for-sale Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Available-for-sale Financial Assets	December 31 2016 2017 NT$ NT$ US$ (Note 4) Unquoted ordinary shares $ 553,350 $ 605,110 $ 20,415 Quoted ordinary shares 146,786 279,791 9,440 Limited partnership 273,372 246,072 8,302 Unquoted preferred shares 78,068 57,367 1,935 Open-end mutual funds 243,458 23,825 804 1,295,034 1,212,165 40,896 Current 266,696 89,159 3,008 Non-current $ 1,028,338 $ 1,123,006 $ 37,888

Trade Receivables, Net (Tables)

Trade Receivables, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Trade Receivables, Net	December 31 2016 2017 NT$ NT$ US$ (Note 4) Trade receivables $ 51,199,266 $ 55,265,607 $ 1,864,562 Less: Allowance for doubtful debts 53,709 64,901 2,190 Trade receivables, net $ 51,145,557 $ 55,200,706 $ 1,862,372
Summary of Aging of Receivables Based on Past Due Date	December 31 2016 2017 NT$ NT$ US$ (Note 4) Not past due $ 45,959,876 $ 49,599,512 $ 1,673,398 1 to 30 days 4,467,435 4,986,491 168,235 31 to 90 days 700,122 562,200 18,968 More than 91 days 71,833 117,404 3,961 Total $ 51,199,266 $ 55,265,607 $ 1,864,562
Trade receivables [member]
Summary of Aging of Receivables Past Due but Not Impaired	Aging of receivables that were past due but not impaired December 31 2016 2017 NT$ NT$ US$ (Note 4) 1 to 30 days $ 4,449,479 $ 4,942,677 $ 166,757 31 to 90 days 596,647 378,526 12,771 Total $ 5,046,126 $ 5,321,203 $ 179,528
Summary of Movement of Allowance for Doubtful Trade Receivables	Movement of the allowance for doubtful trade receivables Impaired Individually Impaired Collectively Total NT$ NT$ NT$ Balance at January 1, 2015 $ 28,305 $ 55,840 $ 84,145 Impairment losses recognized (reversed) 18,816 (10,584 ) 8,232 Amount written off (7,617 ) (209 ) (7,826 ) Effect of foreign currency exchange differences (458 ) (1,187 ) (1,645 ) Balance at December 31, 2015 39,046 43,860 82,906 Impairment losses reversed (21,501 ) (6,521 ) (28,022 ) Effect of foreign currency exchange differences (1,092 ) (83 ) (1,175 ) Balance at December 31, 2016 16,453 37,256 53,709 Impairment losses recognized 9,527 4,102 13,629 Amounts written off - (34 ) (34 ) Effect of foreign currency exchange differences (850 ) (1,553 ) (2,403 ) Balance at December 31, 2017 $ 25,130 $ 39,771 $ 64,901 Impaired Individually Impaired Collectively Total US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1, 2017 $ 555 $ 1,257 $ 1,812 Impairment losses recognized 322 138 460 Amounts written off - (1 ) (1 ) Effect of foreign currency exchange differences (29 ) (52 ) (81 ) Balance at December 31, 2017 $ 848 $ 1,342 $ 2,190

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Inventories	December 31 2016 2017 NT$ NT$ US$ (Note 4) Finished goods $ 6,519,465 $ 6,740,816 $ 227,423 Work in process 2,822,687 3,452,332 116,475 Raw materials 10,850,062 12,625,502 425,962 Supplies 795,093 894,196 30,168 Raw materials and supplies in transit 450,755 548,065 18,491 $ 21,438,062 $ 24,260,911 $ 818,519

Inventories Related to Real E54

Inventories Related to Real Estate Business (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Inventories Related to Real Estate Business	December 31 2016 2017 NT$ NT$ US$ (Note 4) Land and buildings held for sale $ 263,526 $ 25,825 $ 871 Construction in progress 22,236,464 8,106,166 273,488 Land held for construction 1,687,525 1,687,525 56,934 $ 24,187,515 $ 9,819,516 $ 331,293

Other Financial Assets (Tables)

Other Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Other Financial Assets	December 31 2016 2017 NT$ NT$ US$ (Note 4) Unsecured subordinate corporate bonds $ 1,000,000 $ 1,000,000 $ 33,738 Time deposits with original maturity of over three months 480,736 405,520 13,682 Guarantee deposits 178,103 170,594 5,756 Pledged time deposits (Note 36) 206,530 59,456 2,006 Others (Note 36) 13,698 7,270 245 1,879,067 1,642,840 55,427 Current 558,686 472,340 15,936 Non-current $ 1,320,381 $ 1,170,500 $ 39,491

Investments Accounted for Usi56

Investments Accounted for Using the Equity Method (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Investments Accounted for Using the Equity Method	December 31 2016 (Retrospectively Adjusted) 2017 NT$ NT$ US$ (Note 4) Investments in associates $ 49,154,140 $ 48,267,237 $ 1,628,449 Investments in joint venture 670,550 486,514 16,414 $ 49,824,690 $ 48,753,751 $ 1,644,863
Summary of Investments in Associates Accounted for using the Equity Method	a. Investments in associates 1) Investments in associates accounted for using the equity method consisted of the following: Carrying Amount as of December 31 2016 (Retrospectively Adjusted) 2017 Operating NT$ NT$ US$ Name of Associate Main Business Location (Note 4) Material associate Siliconware Precision Industries Co., Ltd. (“SPIL”) Engaged in assembly, testing and turnkey services of integrated circuits ROC $ 45,898,225 $ 45,210,371 $ 1,525,316 Associates that are not individually material Deca Technologies Inc. （ ） Holding company and the group engaged in manufacturing, development and marketing of wafer level packaging and interconnect technology British Cayman Islands 1,813,677 1,583,124 53,412 Hung Ching Development & Construction Co. (“HC”) Engaged in the development, construction and leasing of real estate properties ROC 1,156,833 1,248,711 42,129 Hung Ching Kwan Co. (“HCK”) Engaged in the leasing of real estate properties ROC 321,120 309,630 10,447 (continued) Carrying Amount as of December 31 2016 (Retrospectively Adjusted) 2017 Operating NT$ NT$ US$ Name of Associate Main Business Location (Note 4) Advanced Microelectronic Products Inc. (“AMPI”) Engaged in integrated circuit ROC $ 264,434 $ 215,550 $ 7,272 49,454,289 48,567,386 1,638,576 Less: Deferred gain on transfer of land 300,149 300,149 10,127 $ 49,154,140 $ 48,267,237 $ 1,628,449 (concluded) 2) At each balance sheet date, the percentages of ownership held by the Group were as follows: December 31 2016 2017 SPIL 33.29 % 33.29 % DECA 22.07 % 22.04 % HC 26.22 % 26.22 % HCK 27.31 % 27.31 % AMPI 38.76 % 38.76 %
Summary of Retrospective Adjustments	As of December 31, 2016, the retrospective adjustments are summarized as follows: After Retrospectively Adjusted Before Retrospectively Adjusted NT$ NT$ Investments accounted for using the equity method December 31, 2016 DECA $ 1,813,677 $ 1,820,329 AMPI $ 264,434 $ 266,085
Summary of Fair Values of Investments in Associates with Available Published Price Quotation	5) Fair values (Level 1 inputs in terms of IFRS 13) of investments in associates with available published price quotation are summarized as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) SPIL $ 49,634,805 $ 52,176,190 $ 1,760,330 HC $ 1,310,829 $ 1,695,156 $ 57,191 AMPI $ 307,038 $ 468,572 $ 15,809
Summarized Financial Information	The summarized financial information below represents amounts shown in SPIL’s consolidated financial statements prepared in accordance with IFRSs and adjusted by the Group for equity method accounting purposes. December 31 2016 2017 NT$ NT$ US$ (Note 4) Current assets $ 50,451,295 $ 49,065,912 $ 1,655,395 Non-current assets 107,573,251 101,693,417 3,430,952 Current liabilities (41,088,439 ) (26,194,615 ) (883,759 ) Non-current liabilities (17,518,410 ) (27,213,266 ) (918,126 ) Equity $ 99,417,697 $ 97,351,448 $ 3,284,462 Proportion of the Group’s ownership interest in SPIL 33.29 % 33.29 % 33.29 % Net assets attributable to the Group $ 33,096,151 $ 32,408,297 $ 1,093,397 Goodwill 12,802,074 12,802,074 431,919 Carrying amount $ 45,898,225 $ 45,210,371 $ 1,525,316 (Concluded) For the Year Ended December 31 2016 2017 NT$ NT$ US$ (Note 4) Operating revenue $ 85,111,913 $ 83,554,385 $ 2,818,974 Gross profit $ 15,027,247 $ 12,464,792 $ 420,540 Profit before income tax $ 7,351,661 $ 4,347,810 $ 146,687 Net profit for the year $ 5,484,462 $ 2,822,231 $ 95,217 Other comprehensive income (loss) (2,373,532 ) 579,057 19,536 Total comprehensive income for the year $ 3,110,930 $ 3,401,288 $ 114,753 Cash dividends received from SPIL $ 3,941,740 $ 1,815,275 $ 61,244
Summary of Aggregate Information of Associates that are Not Individually Material	For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) The Group’s share of: Net profit (loss) for the year $ 120,749 $ (139,366 ) $ (190,532 ) $ (6,428 ) Other comprehensive income (loss) for the year (2,916 ) (115,650 ) 59,676 2,013 Total comprehensive income (loss) for the year $ 117,833 $ (255,016 ) $ (130,856 ) $ (4,415 )
Summary of Aggregate Information of the Joint Venture that is Not Individually Material	Aggregate information of the joint venture that is not individually material For the Year Ended December 31 2016 2017 NT$ NT$ US$ (Note 4) The Group’s share of net loss and total comprehensive loss for the year $ (90,478 ) $ (184,366 ) $ (6,220 )

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Property, Plant and Equipment	The carrying amounts of each class of property, plant and equipment were as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Land $ 3,365,013 $ 3,258,518 $ 109,937 Buildings and improvements 58,028,631 58,272,864 1,966,021 Machinery and equipment 72,700,762 66,185,198 2,232,969 Other equipment 2,089,581 1,588,113 53,580 Construction in progress and machinery in transit 7,696,254 5,863,713 197,831 $ 143,880,241 $ 135,168,406 $ 4,560,338 For the year ended December 31, 2015 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total NT$ NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2015 $ 3,348,018 $ 86,725,254 $ 233,669,627 $ 7,182,574 $ 5,862,217 $ 336,787,690 Additions 132,584 553,496 401,417 27,193,324 28,280,821 Disposals - (405,040 ) (8,041,933 ) (232,555 ) (20,711 ) (8,700,239 ) Reclassification - 8,579,472 18,054,712 389,783 (26,893,158 ) 130,809 Effect of foreign currency exchange differences 33,282 (584,338 ) (952,295 ) (18,811 ) 256,088 (1,266,074 ) Balance at December 31, 2015 $ 3,381,300 $ 94,447,932 $ 243,283,607 $ 7,722,408 $ 6,397,760 $ 355,233,007 Accumulated depreciation and impairment Balance at January 1, 2015 $ - $ 30,329,544 $ 149,497,980 $ 5,365,887 $ 7,164 $ 185,200,575 Depreciation expense - 4,790,646 23,372,408 775,716 - 28,938,770 Impairment losses recognized - 120,424 31,116 - 106,589 258,129 Disposals - (308,895 ) (7,838,937 ) (224,509 ) - (8,372,341 ) Reclassification - 5,704 (11,920 ) 3,008 - (3,208 ) Effect of foreign currency exchange differences - (290,545 ) (482,349 ) (12,688 ) (411 ) (785,993 ) Balance at December 31, 2015 $ - $ 34,646,878 $ 164,568,298 $ 5,907,414 $ 113,342 $ 205,235,932 For the year ended December 31, 2016 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total NT$ NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2016 $ 3,381,300 $ 94,447,932 $ 243,283,607 $ 7,722,408 $ 6,397,760 $ 355,233,007 Additions - 22,341 94,480 470,901 27,093,140 27,680,862 Disposals - (684,698 ) (5,956,179 ) (159,822 ) (268,782 ) (7,069,481 ) Reclassification - 5,110,102 19,661,732 691,276 (25,463,285 ) (175 ) Acquisitions through business combinations - - - 1,159 - 1,159 Effect of foreign currency exchange differences (16,287 ) (2,637,502 ) (8,882,884 ) (251,261 ) (45,291 ) (11,833,225 ) Balance at December 31, 2016 $ 3,365,013 $ 96,258,175 $ 248,200,756 $ 8,474,661 $ 7,713,542 $ 364,012,147 Accumulated depreciation and impairment Balance at January 1, 2016 $ - $ 34,646,878 $ 164,568,298 $ 5,907,414 $ 113,342 $ 205,235,932 Depreciation expense - 5,114,263 22,983,290 864,061 - 28,961,614 Impairment losses recognized - 620 876,123 5,564 5,924 888,231 Disposals - (449,198 ) (5,544,489 ) (151,875 ) (100,049 ) (6,245,611 ) Reclassification - (5,123 ) 9,660 (4,537 ) - - Acquisitions through business combinations - - - 824 - 824 Effect of foreign currency exchange differences - (1,077,896 ) (7,392,888 ) (236,371 ) (1,929 ) (8,709,084 ) Balance at December 31, 2016 $ - $ 38,229,544 $ 175,499,994 $ 6,385,080 $ 17,288 $ 220,131,906 For the year ended December 31, 2017 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total NT$ NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2017 $ 3,365,013 $ 96,258,175 $ 248,200,756 $ 8,474,661 $ 7,713,542 $ 364,012,147 Additions - 350,434 102,301 130,659 23,094,288 23,677,682 Disposals - (609,294 ) (8,449,949 ) (763,937 ) (73,248 ) (9,896,428 ) Reclassification (35,965 ) 6,483,392 18,331,738 174,947 (25,428,464 ) (474,352 ) Effect of foreign currency exchange differences (70,530 ) (2,294,779 ) (4,986,843 ) (204,250 ) 557,595 (6,998,807 ) Balance at December 31, 2017 $ 3,258,518 $ 100,187,928 $ 253,198,003 $ 7,812,080 $ 5,863,713 $ 370,320,242 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ 38,229,544 $ 175,499,994 $ 6,385,080 $ 17,288 $ 220,131,906 Depreciation expense - 5,156,558 22,722,307 746,422 - 28,625,287 Impairment losses recognized - 2,310 286,880 368 - 289,558 Disposals - (478,903 ) (7,540,654 ) (720,319 ) (17,288 ) (8,757,164 ) Reclassification - (210,080 ) 34,452 (24,117 ) - (199,745 ) Effect of foreign currency exchange differences - (784,365 ) (3,990,174 ) (163,467 ) - (4,938,006 ) Balance at December 31, 2017 $ - $ 41,915,064 $ 187,012,805 $ 6,223,967 $ - $ 235,151,836 Land Buildings and improvements Machinery and equipment Other equipment Construction in progress and machinery in transit Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Cost Balance at January 1,2017 $ 113,529 $ 3,247,577 $ 8,373,845 $ 285,920 $ 260,241 $ 12,281,112 Additions - 11,823 3,451 4,408 779,160 798,842 Disposals - (20,556 ) (285,086 ) (25,774 ) (2,471 ) (333,887 ) Reclassification (1,212 ) 218,738 618,480 5,902 (857,911 ) (16,003 ) Effect of foreign currency exchange differences (2,380 ) (77,422 ) (168,247 ) (6,891 ) 18,812 (236,128 ) Balance at December 31, 2017 $ 109,937 $ 3,380,160 $ 8,542,443 $ 263,565 $ 197,831 $ 12,493,936 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ 1,289,796 $ 5,921,052 $ 215,421 $ 583 $ 7,426,852 Depreciation expense - 173,973 766,610 25,183 - 965,766 Impairment losses recognized - 78 9,679 12 - 9,769 Disposals - (16,157 ) (254,408 ) (24,302 ) (583 ) (295,450 ) Reclassification - (7,088 ) 1,162 (814 ) - (6,740 ) Effect of foreign currency exchange differences - (26,463 ) (134,621 ) (5,515 ) - (166,599 ) Balance at December 31,2017 $ - $ 1,414,139 $ 6,309,474 $ 209,985 $ - $ 7,933,598
Summary of Property, Plant and Equipment Useful Lives	Each class of property, plant and equipment was depreciated on a straight-line basis over the following useful lives: Buildings and improvements Main plant buildings 10-40 years Cleanrooms 10-20 years Others 3-20 years Machinery and equipment 2-10 years Other equipment 2-20 years

Investment Properties (Tables)

Investment Properties (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Investment Properties	Land Buildings and improvements Total NT$ NT$ NT$ Cost Balance at January 1, 2017 $ - $ - $ - Additions - 186,535 186,535 Disposals - (342 ) (342 ) Transfers from inventories related to real estate business and property, plant and equipment 35,965 8,114,110 8,150,075 Effects of foreign currency exchange differences - 106,482 106,482 Balance at December 31, 2017 $ 35,965 $ 8,406,785 $ 8,442,750 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ - $ - Depreciation expenses - 122,231 122,231 Disposals - (161 ) (161 ) Transfers from property, plant and equipment - 199,745 199,745 Effects of foreign currency exchange differences - 1,499 1,499 Balance at December 31, 2017 $ - $ 323,314 $ 323,314 Land Buildings and improvements Total US$ (Note 4) US$ (Note 4) US$ (Note 4) Cost Balance at January 1, 2017 $ - $ - $ - Additions - 6,293 6,293 Disposals - (11 ) (11 ) Transfers from inventories related to real estate business and property, plant and equipment 1,213 273,755 274,968 Effects of foreign currency exchange differences - 3,593 3,593 Balance at December 31, 2017 $ 1,213 $ 283,630 $ 284,843 Accumulated depreciation and impairment Balance at January 1, 2017 $ - $ - $ - Depreciation expenses - 4,124 4,124 Disposals - (5 ) (5 ) Transfers from property, plant and equipment - 6,739 6,739 Effects of foreign currency exchange differences - 50 50 Balance at December 31, 2017 $ - $ 10,908 $ 10,908
Summary of Investment Properties, Useful Lives	The investment properties are depreciated using the straight-line method over their estimated useful lives as follows: Main buildings 10-40 years Others 3-20 years

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Goodwill	Cost Accumulated impairment Carrying amount NT$ NT$ NT$ Balance at January 1, 2015 $ 12,434,411 $ 1,988,996 $ 10,445,415 Effect of foreign currency exchange differences 61,104 - 61,104 Balance at December 31, 2015 12,495,515 1,988,996 10,506,519 Acquisitions through business combinations (retrospectively adjusted) (Note 28) 15,323 - 15,323 Effect of foreign currency exchange differences (31,533 ) - (31,533 ) Balance at December 31, 2016 (retrospectively adjusted) 12,479,305 1,988,996 10,490,309 Impairment losses recognized - 425,117 (425,117 ) Effect of foreign currency exchange differences (130,698 ) - (130,698 ) Balance at December 31, 2017 $ 12,348,607 $ 2,414,113 $ 9,934,494 Cost Accumulated impairment Carrying amount US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1, 2017 (retrospectively adjusted) (Note 28) $ 421,029 $ 67,105 $ 353,924 Impairment losses recognized - 14,343 (14,343 ) Effect of foreign currency exchange differences (4,409 ) - (4,409 ) Balance at December 31, 2017 $ 416,620 $ 81,448 $ 335,172
Summary of Carrying Amount of Goodwill Allocated to Cash-generating Units	The carrying amount of goodwill allocated to cash-generating units was as follows: December 31 2016 (Retrospectively Adjusted) 2017 Cash-generating units NT$ NT$ US$ (Note 4) Testing segment $ 7,868,961 $ 7,775,581 $ 262,334 Others 2,621,348 2,158,913 72,838 $ 10,490,309 $ 9,934,494 $ 335,172

Other Intangible Assets (Tables

Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Carrying Amounts of Each Class of Other Intangible Assets	The carrying amounts of each class of other intangible assets were as follows: December 31 2016 (Retrospectively Adjusted) 2017 NT$ NT$ US$ (Note 4) Customer relationships $ 194,089 $ 113,776 $ 3,839 Computer software 943,527 864,331 29,161 Patents and acquired specific technology 359,227 319,402 10,776 Others 120,418 109,356 3,689 $ 1,617,261 $ 1,406,865 $ 47,465 For the year ended December 31, 2015 Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2015 $ 1,579,015 $ 2,882,932 $ 2,139,138 $ 184,409 $ 6,785,494 Additions - 481,412 209 9,514 491,135 Disposals or derecognization (663,379 ) (8,426 ) (1,983,914 ) (204 ) (2,655,923 ) Reclassification - 12,360 - - 12,360 Effect of foreign currency exchange differences - (29,918 ) (1,351 ) (381 ) (31,650 ) Balance at December 31, 2015 $ 915,636 $ 3,338,360 $ 154,082 $ 193,338 $ 4,601,416 Accumulated amortization Balance at January 1, 2015 $ 1,077,514 $ 2,084,805 $ 2,118,254 $ 37,050 $ 5,317,623 Amortization expense 227,099 325,856 9,461 17,478 579,894 Disposals or derecognization (663,379 ) (7,402 ) (1,983,914 ) - (2,654,695 ) Reclassification - 3,190 - - 3,190 Effect of foreign currency exchange differences - (21,411 ) (5,415 ) 137 (26,689 ) Balance at December 31, 2015 $ 641,234 $ 2,385,038 $ 138,386 $ 54,665 $ 3,219,323 For the year ended December 31, 2016 (Retrospectively Adjusted) Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2016 $ 915,636 $ 3,338,360 $ 154,082 $ 193,338 $ 4,601,416 Additions (Note 35) - 372,188 301,351 1,605 675,144 Disposals or derecognization (41,099 ) (80,537 ) (1,310 ) - (122,946 ) Reclassification - - 786 - 786 Acquisitions through business combinations 41,099 - 64,380 30 105,509 Effect of foreign currency exchange differences - (77,782 ) (4,846 ) (2,581 ) (85,209 ) Balance at December 31, 2016 $ 915,636 $ 3,552,229 $ 514,443 $ 192,392 $ 5,174,700 (continued) Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Accumulated amortization Balance at January 1, 2016 $ 641,234 $ 2,385,038 $ 138,386 $ 54,665 $ 3,219,323 Amortization expense 121,412 345,836 24,154 17,421 508,823 Disposals or derecognization (41,099 ) (58,765 ) (1,310 ) - (101,174 ) Reclassification - - 786 - 786 Acquisitions through business combinations - - 483 23 506 Effect of foreign currency exchange differences - (63,407 ) (7,283 ) (135 ) (70,825 ) Balance at December 31, 2016 $ 721,547 $ 2,608,702 $ 155,216 $ 71,974 $ 3,557,439 (concluded) For the year ended December 31, 2017 Customer relationships Computer software Patents and acquired specific technology Others Total NT$ NT$ NT$ NT$ NT$ Cost Balance at January 1, 2017 (retrospectively adjusted) $ 915,636 $ 3,552,229 $ 514,443 $ 192,392 $ 5,174,700 Additions - 265,497 - 12,328 277,825 Disposals - (83,595 ) (123,744 ) (4,978 ) (212,317 ) Effect of foreign currency exchange differences - (47,679 ) (1,213 ) (988 ) (49,880 ) Balance at December 31, 2017 $ 915,636 $ 3,686,452 $ 389,486 $ 198,754 $ 5,190,328 Accumulated amortization Balance at January 1, 2017 (retrospectively adjusted) $ 721,547 $ 2,608,702 $ 155,216 $ 71,974 $ 3,557,439 Amortization expense 80,313 316,580 43,493 17,280 457,666 Disposals - (72,481 ) (123,743 ) - (196,224 ) Effect of foreign currency exchange differences - (30,680 ) (4,882 ) 144 (35,418 ) Balance at December 31, 2017 $ 801,860 $ 2,822,121 $ 70,084 $ 89,398 $ 3,783,463 Customer relationships Computer software Patents and acquired specific technology Others Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Cost Balance at January 1, 2017 (retrospectively adjusted) $ 30,892 $ 119,846 $ 17,356 $ 6,491 $ 174,585 Additions - 8,957 - 416 9,373 Disposals - (2,820 ) (4,175 ) (168 ) (7,163 ) Effect of foreign currency exchange differences - (1,609 ) (41 ) (34 ) (1,684 ) Balance at December 31, 2017 $ 30,892 $ 124,374 $ 13,140 $ 6,705 $ 175,111 Accumulated amortization Balance at January 1, 2017 (retrospectively adjusted) $ 24,343 $ 88,012 $ 5,237 $ 2,428 $ 120,020 Amortization expense 2,710 10,681 1,467 583 15,441 Disposals - (2,445 ) (4,175 ) - (6,620 ) Effect of foreign currency exchange differences - (1,035 ) (165 ) 5 (1,195 ) Balance at December 31, 2017 $ 27,053 $ 95,213 $ 2,364 $ 3,016 $ 127,646
Summary of Other Intangible Assets Useful Lives	Each class of other intangible assets were amortized on the straight-line basis over the following useful lives: Customer relationships 11 years Computer software 2-10 years Patents and acquired specific technology 5-15 years Others 5-32 years

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Long Term Bank Loans [member]
Summary of Borrowings	The others were long-term bank loans with floating interest rates and consisted of the followings: December 31 2016 2017 NT$ NT$ US$ (Note 4) Working capital bank loans Syndicated bank loans - repayable through January 2018 to July 2018, annual interest rates were 2.55% and 2.61% -2.70% as of December 31, 2016 and 2017, respectively $ 9,223,500 $ 4,761,600 $ 160,647 Others - repayable through January 2018 to December 2019, annual interest rates were 0.74%-4.48% and 0.93%-2.10% as of December 31, 2016 and 2017, respectively 36,009,917 22,441,947 757,151 Mortgage loans Repayable through July 2018 to June 2023, annual interest rates were both 4.95%-5.39% as of December 31, 2016 and 2017 4,390,003 4,705,149 158,743 49,623,420 31,908,696 1,076,541 Less: unamortized arrangement fee 7,198 1,200 40 49,616,222 31,907,496 1,076,501 Less: current portion 6,567,565 6,761,625 228,125 $ 43,048,657 $ 25,145,871 $ 848,376
Longterm Bills Payable [member]
Summary of Borrowings	2) Long-term bills payable December 31 2016 2017 NT$ NT$ US$ (Note 4) China Bills Finance Corporation, repayable in February 2019, annual interest rate was 0.96% $ - $ 1,000,000 $ 33,738 International Bills Finance Corporation, repayable in March 2019, annual interest rate was 0.96% - 1,000,000 33,738 Ta Ching Bills Finance Corporation, annual interest rates was 1.00% and has been repaid in December 2017 2,000,000 - - 2,000,000 2,000,000 67,476 Less: unamortized discounts 659 868 29 Long-term borrowings $ 1,999,341 $ 1,999,132 $ 67,447 2) Long-term bills payable December 31 2016 2017 NT$ NT$ US$ (Note 4) China Bills Finance Corporation, repayable in February 2019, annual interest rate was 0.96% $ - $ 1,000,000 $ 33,738 International Bills Finance Corporation, repayable in March 2019, annual interest rate was 0.96% - 1,000,000 33,738 Ta Ching Bills Finance Corporation, annual interest rates was 1.00% and has been repaid in December 2017 2,000,000 - - 2,000,000 2,000,000 67,476 Less: unamortized discounts 659 868 29 Long-term borrowings $ 1,999,341 $ 1,999,132 $ 67,447

Bonds Payable (Tables)

Bonds Payable (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Bonds Payable	December 31 2016 2017 NT$ NT$ US$ (Note 4) Unsecured domestic bonds Repayable at maturity in January 2021 and interest due annually with annual interest rate at 1.30% $ 7,000,000 $ 7,000,000 $ 236,168 Repayable at maturity in January 2023 and interest due annually with annual interest rate at 1.50% 2,000,000 2,000,000 67,476 Repayable at maturity in January 2022 and interest due annually with annual interest rate at 1.25% - 3,700,000 124,831 Repayable at maturity in January 2024 and interest due annually with annual interest rate at 1.45% - 4,300,000 145,074 Unsecured convertible overseas bonds US$400,000 thousand 12,900,000 - - US$200,000 thousand (linked to New Taiwan dollar) 6,185,600 6,185,600 208,691 Secured overseas bonds - secured by the Company US$300,000 thousand, interest due semi-annually with annual interest rate at 2.125% and has been repaid in July 2017 9,675,000 - - 37,760,600 23,185,600 782,240 Less: discounts on bonds payable 760,697 42,820 1,444 36,999,903 23,142,780 780,796 Less: current portion 9,658,346 6,161,197 207,868 $ 27,341,557 $ 16,981,583 $ 572,928

Other Payables (Tables)

Other Payables (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Other Payables	December 31 2016 2017 NT$ NT$ US$ (Note 4) Accrued salary and bonus $ 6,606,406 $ 7,292,254 $ 246,027 Payables for property, plant and equipment 5,605,528 4,623,268 155,981 Accrued employees’ compensation and remuneration to directors 2,400,778 2,568,880 86,669 Accrued employee insurance 617,419 657,176 22,172 Accrued utilities 410,796 417,257 14,077 Payables for patents and acquired specific technology (Note 35) 120,938 93,000 3,138 Others 5,760,169 5,726,052 193,187 $ 21,522,034 $ 21,377,887 $ 721,251

Retirement Benefit Plans (Table

Retirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Defined Benefit Plans Amounts Included in Consolidated Balance Sheets	The amounts included in the consolidated balance sheets arising from the Group’s obligation in respect of its defined benefit plans excluding those for executive managers were as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Present value of the defined benefit obligation $ 8,389,884 $ 7,910,638 $ 266,891 Fair value of plan assets (4,417,367 ) (4,341,373 ) (146,470 ) Present value of unfunded defined benefit obligation 3,972,517 3,569,265 120,421 Recorded under other payables (22,273 ) (24,638 ) (831 ) Recorded under other current assets 15,542 182,421 6,154 Net defined benefit liability $ 3,965,786 $ 3,727,048 $ 125,744
Summary of Movements in Net Defined Benefit Liability (Asset)	Movements in net defined benefit liability (asset) were as follows: Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) NT$ NT$ NT$ Balance at January 1, 2015 $ 7,674,293 $ (3,502,487 ) $ 4,171,806 Service cost Current service cost 335,655 - $ 335,655 Net interest expense (income) 183,889 (108,356 ) 75,533 Recognized in profit or loss 519,544 (108,356 ) 411,188 Remeasurement Return on plan assets (excluding amounts included in net interest) - 12,426 12,426 Actuarial loss arising from changes in financial assumptions 309,695 - 309,695 Actuarial gain arising from experience adjustments (243,363 ) - (243,363 ) Actuarial gain arising from changes in demographic assumptions (15,847 ) - (15,847 ) Recognized in other comprehensive income 50,485 12,426 62,911 Contributions from the employer - (611,581 ) (611,581 ) Benefits paid from the pension fund (192,928 ) 192,928 - Benefits paid from the Group (43,088 ) - (43,088 ) Exchange differences on foreign plans (34,630 ) 43,341 8,711 Balance at December 31, 2015 7,973,676 (3,973,729 ) 3,999,947 Service cost Current service cost 329,838 - 329,838 Net interest expense (income) 167,111 (109,080 ) 58,031 Recognized in profit or loss 496,949 (109,080 ) 387,869 Remeasurement Return on plan assets (excluding amounts included in net interest) - 54,549 54,549 Actuarial loss arising from changes in financial assumptions 156,193 - 156,193 Actuarial loss arising from experience adjustments 200,723 - 200,723 Actuarial loss arising from changes in demographic assumptions 5,716 - 5,716 Recognized in other comprehensive income 362,632 54,549 417,181 Contributions from the employer - (807,232 ) (807,232 ) Benefits paid from the pension fund (308,471 ) 308,471 - Benefits paid from the Group (36,033 ) - (36,033 ) (Continued) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) NT$ NT$ NT$ Liabilities assumed in a business combination $ 535 $ (535 ) $ - Exchange differences on foreign plans (99,404 ) 110,189 10,785 Balance at December 31, 2016 8,389,884 (4,417,367 ) 3,972,517 Service cost Current service cost 278,412 - 278,412 Past service cost and gain on settlements (68,979 ) - (68,979 ) Net interest expense (income) 157,404 (103,741 ) 53,663 Recognized in profit or loss 366,837 (103,741 ) 263,096 Remeasurement Return on plan assets (excluding amounts included in net interest) - 52,124 52,124 Actuarial loss arising from changes in financial assumptions 56,860 - 56,860 Actuarial gain arising from experience adjustments (315,090 ) - (315,090 ) (Continued) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) NT$ NT$ NT$ Actuarial loss arising from changes in demographic assumptions $ 762 $ - $ 762 Recognized in other comprehensive income (257,468 ) 52,124 (205,344 ) Contributions from the employer - (484,790 ) (484,790 ) Benefits paid from the pension fund (690,830 ) 690,830 - Benefits paid from the Group (96,575 ) - (96,575 ) Exchange differences on foreign plans 198,790 (78,429 ) 120,361 Balance at December 31, 2017 $ 7,910,638 $ (4,341,373 ) $ 3,569,265 (Concluded) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1, 2017 $ 283,060 $ (149,034 ) $ 134,026 Service cost Current service cost 9,393 - 9,393 Past service cost and gain on settlements (2,328 ) - (2,328 ) Net interest expense (income) 5,311 (3,500 ) 1,811 Recognized in profit or loss 12,376 (3,500 ) 8,876 (Continued) Present value of the defined benefit obligation Fair value of the plan assets Net defined benefit liability (asset) US$ (Note 4) US$ (Note 4) US$ (Note 4) Remeasurement Return on plan assets (excluding amounts included in net interest) $ - $ 1,759 $ 1,759 Actuarial loss arising from changes in financial assumptions 1,918 - 1,918 Actuarial gain arising from experience adjustments (10,631 ) - (10,631 ) Actuarial loss arising from changes in demographic assumptions 26 - 26 Recognized in other comprehensive income (8,687 ) 1,759 (6,928 ) Contributions from the employer - (16,356 ) (16,356 ) Benefits paid from the pension fund (23,307 ) 23,307 - Benefits paid from the Group (3,258 ) - (3,258 ) Exchange differences on foreign plans 6,707 (2,646 ) 4,061 Balance at December 31, 2017 $ 266,891 $ (146,470 ) $ 120,421
Summary of Fair Value of the Plan Assets by Major Categories	The fair value of the plan assets by major categories at each balance sheet date was as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Cash $ 2,232,367 $ 2,317,764 $ 78,197 Debt instruments 1,030,384 691,619 23,334 Equity instruments 1,071,777 1,254,109 42,311 Others 82,839 77,881 2,628 Total $ 4,417,367 $ 4,341,373 $ 146,470
Summary of Key Assumptions Used for the Actuarial Valuations	The present value of the defined benefit obligation and the related current service cost and past service cost were measured using the Projected Unit Credit Method. Except the pension plans for executive managers, the key assumptions used for the actuarial valuations were as follow: December 31 2016 2017 Discount rates 0.06%-3.58% 0.06%-3.85% Expected rates of salary increase 2.00%-4.42% 2.00%-4.42%
Summary of Sensitivity Analysis on Defined Obligations	The sensitivity analysis below has been determined based on reasonably possible changes of the respective assumptions occurring at each balance sheet date, while holding all other assumptions constant. December 31 2016 2017 NT$ NT$ US$ (Note 4) Discount Rate 0.5% higher $ (464,647 ) $ (455,158 ) $ (15,356 ) 0.5% lower $ 508,862 $ 461,891 $ 15,583 Expected rates of salary increase 0.5% higher $ 500,051 $ 453,792 $ 15,310 0.5% lower $ (452,956 ) $ (444,493 ) $ (14,996 )
Summary of Maturity Analysis of Undiscounted Pension Benefit	Maturity analysis of undiscounted pension benefit December 31 2016 2017 NT$ NT$ US$ (Note 4) No later than 1 year $ 292,100 $ 291,152 $ 9,823 Later than 1 year and not later than 5 years 1,673,549 1,551,496 52,345 Later than 5 years 17,129,585 16,507,747 556,941 $ 19,095,234 $ 18,350,395 $ 619,109

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Share Capital	Share capital Ordinary shares December 31, 2016 December 31, 2017 Numbers of shares authorized (in thousands) 10,000,000 10,000,000 Numbers of shares reserved (in thousands) Employee share options 800,000 800,000 Number of shares issued and fully paid (in thousands) 7,946,184 8,738,079 December 31, 2016 December 31, 2017 NT$ NT$ US$ (Note 4) Share capital authorized $ 100,000,000 $ 100,000,000 $ 3,373,819 Share capital reserved Employee share options $ 8,000,000 $ 8,000,000 $ 269,906 Share capital issued $ 79,568,040 $ 87,380,787 $ 2,948,070
Summary of Capital Surplus	Capital surplus December 31 2016 2017 NT$ NT$ US$ (Note 4) May be used to offset a deficit, distributed as cash dividends, or transferred to share capital (1) Arising from issuance of ordinary shares $ 5,844,397 $ 21,553,853 $ 727,188 Arising from conversion of bond payable - 1,930,066 65,117 Arising from the difference between consideration received and the carrying amount of the subsidiaries’ net assets during actual disposal or acquisition 7,176,958 7,176,958 242,137 May be used to offset a deficit only Arising from changes in percentage of ownership interest in subsidiaries (2) 6,134,228 6,084,895 205,293 Arising from treasury share transactions 950,368 1,151,345 38,844 Arising from exercised employee share options 630,411 1,089,178 36,747 Arising from expired employee share options (Note 27) 3,626 223,454 7,539 Arising from share of changes in capital surplus of associates 82,243 83,733 2,825 May not be used for any purpose Arising from employee share options 1,230,247 960,888 32,419 Arising from equity component of convertible bonds 214,022 214,022 7,221 Others (3) - 155,936 5,261 $ 22,266,500 $ 40,624,328 $ 1,370,591 1) Such capital surplus may be used to offset a deficit; in addition, when the Company has no deficit, such capital surplus may be distributed as cash dividends or transferred to share capital (limited to a certain percentage of the Company’s capital surplus and once a year). 2) Such capital surplus arises from the effect of changes in ownership interest in a subsidiary resulted from equity transactions other than actual disposal or acquisition, or from changes in capital surplus of subsidiaries accounted for using the equity method. 3) Such capital surplus arises from the excess of related carrying amount of related accounts over the par value and the Company has not completed registration formalities when the convertible bonds were converted into ordinary shares and employee share options were exercised.
Summary of Appropriations of Earnings	The appropriations of earnings for 2015 and 2016 resolved at the Company’s annual shareholders’ meetings in June 2016 and June 2017, respectively, were as follows: Appropriation of Earnings Dividends Per Share For Year 2015 For Year 2016 For Year 2015 For Year 2016 NT$ NT$ NT$ NT$ (in dollars) (in dollars) Legal reserve $ 1,947,887 $ 2,168,034 Cash dividends 12,476,779 11,415,198 $ 1.60 $ 1.40 $ 14,424,666 $ 13,583,232
Summary of Treasury Shares	Treasury shares (in thousand shares) Balance at Balance at January 1 Addition Decrease December 31 2015 Shares held by subsidiaries 145,883 - - 145,883 Shares reserved for bonds conversion - 120,000 - 120,000 145,883 120,000 - 265,883 Balance at Balance at January 1 Addition Decrease December 31 2016 Shares held by subsidiaries 145,883 - - 145,883 Shares reserved for bonds conversion 120,000 - - 120,000 265,883 - - 265,883 2017 Shares held by subsidiaries 145,883 - - 145,883 Shares reserved for bonds conversion 120,000 - - 120,000 265,883 - - 265,883
Summary of Shares Held By Subsidiaries	The Company’s shares held by its subsidiaries at each balance sheet date were as follows: Shares Held By Subsidiaries Carrying amount Carrying amount Fair Value Fair Value (in thousand shares) NT$ US$ (Note 4) NT$ US$ (Note 4) December 31, 2016 ASE Test 88,200 $ 1,380,721 $ 2,915,026 J&R Holding 46,704 381,709 1,543,559 ASE Test, Inc. 10,979 196,677 362,849 145,883 $ 1,959,107 $ 4,821,434 December 31, 2017 ASE Test 88,200 $ 1,380,721 $ 46,583 $ 3,364,848 $ 113,524 J&R Holding 46,704 381,709 12,878 1,781,749 60,113 ASE Test, Inc. 10,979 196,677 6,636 418,840 14,131 145,883 $ 1,959,107 $ 66,097 $ 5,565,437 $ 187,768
Summary of Non-controlling Interests	Non-controlling interests For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 8,209,860 $ 11,492,545 $ 12,000,551 $ 404,877 Attributable to Non-controlling interests: Share of profit for the year (Note 28) 968,567 1,253,438 1,677,941 56,611 Exchange difference on translating foreign operations (74,968 ) (601,787 ) (334,920 ) (11,300 ) Unrealized gain on available-for-sale financial assets 3,928 1,129 5,763 194 (Continued) For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Defined benefit plan actuarial gains (losses) $ (3,440 ) $ 8,846 $ (13,724 ) $ (463 ) Non-controlling interests arising from acquisition of subsidiaries (Note 28) - 42,857 - - Partial disposal of subsidiaries (Note 30) 1,712,836 26,436 (3,055 ) (103 ) Repurchase of outstanding ordinary shares of subsidiaries (Note 30) - (912,886 ) - - Spin-off of subsidiaries 3,006 - - - Non-controlling interest relating to outstanding vested employee share options held by the employees of subsidiaries 904,904 927,823 263,213 8,880 Non-controlling interest relating to outstanding expired employee share options - - (159,200 ) (5,371 ) Cash dividends to non-controlling interests (232,148 ) (237,850 ) (246,440 ) (8,314 ) Balance at December 31 $ 11,492,545 $ 12,000,551 $ 13,190,129 $ 445,011
Exchange differences on translating foreign operations [member]
Summary of Other Reserves	Exchange differences on translating foreign operations For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 4,540,862 $ 4,492,671 $ (1,643,623 ) $ (55,453 ) Exchange differences arising on translating foreign operations 11,459 (5,843,856 ) (4,952,815 ) (167,099 ) Share of exchange difference of associates and joint venture accounted for using the equity method (59,650 ) (292,438 ) (137,221 ) (4,630 ) Balance at December 31 $ 4,492,671 $ (1,643,623 ) $ (6,733,659 ) $ (227,182 )
Unrealized gain (loss) on available-for-sale financial assets [member]
Summary of Other Reserves	Unrealized gain (loss) on available-for-sale financial assets For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 526,778 $ 588,119 $ (197,314 ) $ (6,657 ) Unrealized gain (loss) arising on revaluation of available-for-sale financial assets (4,304 ) (257,240 ) 169,585 5,721 Cumulative loss reclassified to profit or loss on impairment of available-for-sale financial assets - - 50,206 1,694 Cumulative loss (gain) reclassified to profit or loss on disposal of available-for-sale financial assets 10,827 7,512 (1,517 ) (51 ) Share of unrealized gain (loss) on available-for-sale financial assets of associates and joint venture accounted for using the equity method 54,818 (535,705 ) 401,610 13,550 Balance at December 31 $ 588,119 $ (197,314 ) $ 422,570 $ 14,257

Profit Before Income Tax (Table

Profit Before Income Tax (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Other Operating Income and Expenses, Net	a. Other operating income and expenses, net For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Rental income $ 60,230 $ 51,607 $ 131,570 $ 4,439 Gain (loss) on disposal of property, plant and equipment and other assets (127,111 ) (127,159 ) 367,110 12,386 Impairment loss on property, plant and equipment and goodwill (258,129 ) (888,231 ) (714,675 ) (24,112 ) Loss on damages and claims (116,445 ) (12,778 ) (85,585 ) (2,888 ) Others 189,926 176,281 410,136 13,837 $ (251,529 ) $ (800,280 ) $ 108,556 $ 3,662
Summary of Other Income	b. Other income For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Government subsidy $ 176,721 $ 332,758 $ 341,844 $ 11,533 Interest income 242,084 230,067 306,871 10,353 Dividends income 396,973 26,411 59,039 1,992 $ 815,778 $ 589,236 $ 707,754 $ 23,878
Summary of Other Gains and Losses	c. Other gains and losses For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Gain on disposal of subsidiaries (Note 29) $ - $ - $ 5,589,457 $ 188,578 Net gain (loss) arising on financial instruments held for trading 1,657,093 $ 224,446 (3,111,253 ) (104,968 ) Net gain on financial assets designated as at FVTPL 815,742 223,113 327,351 11,044 Foreign exchange gain or loss, net (713,213 ) 1,928,384 3,502,586 118,171 Impairment loss on financial assets - (91,886 ) (50,206 ) (1,694 ) Others (10,827 ) (7,513 ) 1,518 52 $ 1,748,795 $ 2,276,544 $ 6,259,453 $ 211,183
Summary of Finance Costs	d. Finance costs For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Total interest expense for financial liabilities measured at amortized cost $ 2,514,208 $ 2,510,197 $ 2,016,298 $ 68,026 Less: Amounts included in the cost of qualifying assets Inventories related to real estate business (197,287 ) (238,469 ) (190,137 ) (6,415 ) Property, plant and equipment (48,135 ) (54,191 ) (51,262 ) (1,729 ) Investment property - - (13 ) - 2,268,786 2,217,537 1,774,886 59,882 Other finance costs 43,357 43,538 24,608 830 $ 2,312,143 $ 2,261,075 $ 1,799,494 $ 60,712
Summary of Capitalized Borrowing Costs	Information relating to the capitalized borrowing costs was as follows: For the Year Ended December 31 2015 2016 2017 Annual interest capitalization rates Inventories related to real estate business(%) 4.35-6.77 4.35-6.00 4.35-5.39 Property, plant and equipment(%) 0.75-6.15 1.15-4.42 1.26-5.49 Investment properties (%) - - 1.26-1.97
Summary of Depreciation and Amortization	e. Depreciation and amortization For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Property, plant and equipment $ 28,938,770 $ 28,961,614 $ 28,625,287 $ 965,766 Investment properties - - 122,231 4,124 Intangible assets 579,894 508,823 457,666 15,441 Total $ 29,518,664 $ 29,470,437 $ 29,205,184 $ 985,331 Summary of depreciation by function Operating costs $ 27,023,957 $ 26,948,106 $ 26,731,714 $ 901,880 Operating expenses 1,914,813 2,013,508 2,015,804 68,010 $ 28,938,770 $ 28,961,614 $ 28,747,518 $ 969,890 (Continued) For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Summary of amortization by function Operating costs $ 124,235 $ 152,987 $ 140,175 $ 4,729 Operating expenses 455,659 355,836 317,491 10,712 $ 579,894 $ 508,823 $ 457,666 $ 15,441 (Concluded)
Summary of Operating Expenses Directly Related to Investment Properties	f. Operating expenses directly related to investment properties For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Direct operating expenses of investment properties that generated rental income $ - $ - $ 465,458 $ 15,704
Summary of Employee Benefits Expense	g. Employee benefits expense For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Post-employment benefits Defined contribution plans $ 2,324,737 $ 2,356,416 $ 2,340,826 $ 78,975 Defined benefit plans 413,490 394,741 266,267 8,983 2,738,227 2,751,157 2,607,093 87,958 Equity-settled share-based payments 133,496 470,788 438,765 14,803 Other employee benefits 47,883,464 49,525,940 51,043,198 1,722,105 $ 50,755,187 $ 52,747,885 $ 54,089,056 $ 1,824,866 Summary of employee benefits expense by function Operating costs $ 34,720,359 $ 35,588,529 $ 35,978,403 $ 1,213,846 Operating expenses 16,034,828 17,159,356 18,110,653 611,020 $ 50,755,187 $ 52,747,885 $ 54,089,056 $ 1,824,866
Summary of Employees' Compensation and Remuneration to Directors	For the years ended December 31, 2015, 2016 and 2017, the employees’ compensation and the remuneration to directors were accrued based on 8.25% and 0.75% of net profit before income tax, employees’ compensation and remuneration to directors, respectively, and were as follows. For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Employees’ compensation $ 2,033,500 $ 2,147,323 $ 2,291,140 $ 77,299 Remuneration to directors 184,500 195,211 208,285 7,027
Summary of Appropriations of Employees' Compensation (Settled by Cash) and Remuneration to Directors	The appropriations of employees’ compensation (settled by cash) and remuneration to directors for 2015 and 2016 resolved by the board of directors in April 2016 and in March 2017, respectively, and the amounts recognized in 2015 and 2016 consolidated financial statements were as follows. For Year 2015 For Year 2016 Employees’ compensation Remuneration to directors Employees’ compensation Remuneration to directors NT$ NT$ NT$ NT$ Resolved by the board of directors $ 2,033,800 $ 140,000 $ 2,151,900 $ 148,000 Recognized in the consolidated financial statements $ 2,033,500 $ 184,500 $ 2,147,323 $ 195,211

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Major Components of Income Tax Expense	The major components of income tax were as follows: For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Current income tax In respect of the current year $ 4,029,076 $ 4,177,900 $ 4,979,766 $ 168,008 Income tax on unappropriated earnings 187,654 829,345 1,076,353 36,314 Changes in estimate for prior years (20,719 ) 28,160 (88,162 ) (2,974 ) 4,196,011 5,035,405 5,967,957 201,348 For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Deferred income tax In respect of the current year $ 190,829 $ 574,541 $ 534,472 $ 18,032 Adjustments attributable to changes in tax rates 3,794 14,184 - - Changes in estimate for prior years (20,890 ) (206,788 ) 52,872 1,784 Effect of foreign currency exchange differences (58,671 ) (26,498 ) (31,698 ) (1,070 ) 115,062 355,439 555,646 18,746 Income tax recognized in profit or loss $ 4,311,073 $ 5,390,844 $ 6,523,603 $ 220,094
Summary of Reconciliation of Income Tax Expense	A reconciliation of income tax expense calculated at the statutory rates and income tax expense recognized in profit or loss was as follows: For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Profit before income tax $ 25,011,788 $ 27,968,705 $ 31,020,663 $ 1,046,581 Income tax expense calculated at the statutory rates $ 6,307,148 $ 8,634,187 $ 10,890,498 $ 367,426 Nontaxable expense in determining taxable income 160,530 (34,954 ) 483,715 16,319 Tax-exempt income (537,987 ) (700,274 ) (623,566 ) (21,038 ) Additional income tax on unappropriated earnings 338,142 829,345 1,076,353 36,314 Loss carry-forward and income tax credits currently used (1,286,705 ) (898,700 ) (1,124,043 ) (37,923 ) Remeasurement of deferred income tax assets, net (688,584 ) (2,797,673 ) (4,131,473 ) (139,389 ) Changes in estimate for prior years (20,719 ) 28,160 (88,162 ) (2,974 ) Withholding tax 39,248 81,543 40,281 1,359 Land value increment tax - 249,210 - - Income tax expense recognized in profit or loss $ 4,311,073 $ 5,390,844 $ 6,523,603 $ 220,094
Summary of Income Tax Recognized Directly in Equity	b. Income tax recognized directly in equity For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Deferred income tax Related to employee share options $ (33 ) $ (204 ) $ 262 $ 9
Summary of Income Tax Recognized in Other Comprehensive Income	c. Income tax recognized in other comprehensive income For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Deferred income tax Related to remeasurement of defined benefit plans $ 11,002 $ 73,637 $ (51,217 ) $ (1,728 )
Summary of Current Tax Assets and Liabilities	d. Current tax assets and liabilities December 31 2016 2017 NT$ NT$ US$ (Note 4) Current tax assets Tax refund receivable $ 260,559 $ 28,458 $ 960 Prepaid income tax 211,193 232,084 7,830 $ 471,752 $ 260,542 $ 8,790 Current tax liabilities Income tax payable $ 6,846,350 $ 7,619,328 $ 257,062
Summary of Movements of Deferred Tax Assets and Deferred Tax Liabilities	The movements of deferred tax assets and deferred tax liabilities were as follows: Balance at January 1 Recognized in Profit or Loss Recognized in Other Comprehensive Income Recognized in Equity Exchange Differences Acquisitions through business combinations Balance at December 31 NT$ NT$ NT$ NT$ NT$ NT$ NT$ Year ended December 31, 2015 Temporary differences Property, plant and equipment $ (2,431,855 ) $ (1,083,273 ) $ - $ - $ 10,670 $ - $ (3,504,458 ) Defined benefit obligation 796,642 20,398 11,002 - 17,897 - 845,939 FVTPL financial instruments (170,059 ) (62,152 ) - - 13 - (232,198 ) Others 1,166,297 229,799 - (33 ) (11,076 ) - 1,384,987 (638,975 ) (895,228 ) 11,002 (33 ) 17,504 - (1,505,730 ) Loss carry-forward 519,898 812,217 - - (8,538 ) - 1,323,577 Investment credits 452,331 (32,904 ) - - (68,308 ) - 351,119 Others (853 ) 853 - - - - - $ 332,401 $ (115,062 ) $ 11,002 $ (33 ) $ (59,342 ) $ - $ 168,966 Year ended December 31, 2016 Temporary differences Property, plant and equipment $ (3,504,458 ) $ (182,291 ) $ - $ - $ (72,098 ) $ - $ (3,758,847 ) Defined benefit obligation 845,939 (48,601 ) 73,637 - 2,509 - 873,484 FVTPL financial instruments (232,198 ) 212,737 - - (1,902 ) - (21,363 ) Others 1,384,987 (283,179 ) - (204 ) (21,780 ) - 1,079,824 (1,505,730 ) (301,334 ) 73,637 (204 ) (93,271 ) - (1,826,902 ) Loss carry-forward 1,323,577 (110,967 ) - - (91,008 ) 2,939 1,124,541 Investment credits 351,119 56,862 - - (25,245 ) - 382,736 $ 168,966 $ (355,439 ) $ 73,637 $ (204 ) $ (209,524 ) $ 2,939 $ (319,625 ) Year ended December 31, 2017 Temporary differences Property, plant and equipment $ (3,758,847 ) $ (101,576 ) $ - $ - $ (18,643 ) $ - $ (3,879,066 ) Defined benefit obligation 873,484 (26,736 ) (51,217 ) - (15,291 ) - 780,240 FVTPL financial instruments (21,363 ) (86,342 ) - - 2,802 - (104,903 ) Others 1,079,824 (22,748 ) - 262 (28,929 ) - 1,028,409 (1,826,902 ) (237,402 ) (51,217 ) 262 (60,061 ) - (2,175,320 ) Loss carry-forward 1,124,541 (456,246 ) - - 13,146 - 681,441 Investment credits 382,736 138,002 - - 13,475 - 534,213 $ (319,625 ) $ (555,646 ) $ (51,217 ) $ 262 $ (33,440 ) $ - $ (959,666 ) Balance at January 1 Recognized in Profit or Loss Recognized in Other Comprehensive Income Recognized in Equity Exchange Differences Acquisitions through business combinations Balance at December 31 US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Year ended December 31, 2017 Temporary differences Property, plant and equipment $ (126,817 ) $ (3,427 ) $ - $ - $ (629 ) $ - $ (130,873 ) Defined benefit obligation 29,470 (902 ) (1,728 ) - (516 ) - 26,324 FVTPL financial instruments (721 ) (2,913 ) - - 94 - (3,540 ) Others 36,431 (767 ) - 9 (976 ) - 34,697 (61,637 ) (8,009 ) (1,728 ) 9 (2,027 ) - (73,392 ) Loss carry-forward 37,940 (15,393 ) - - 444 - 22,991 Investment credits 12,913 4,656 - - 454 - 18,023 $ (10,784 ) $ (18,746 ) $ (1,728 ) $ 9 $ (1,129 ) $ - $ (32,378 )
Summary of Unrecognized Deferred Tax Assets Related to Loss Carry-forward, Investment Credits and Deductible Temporary Differences	Unrecognized deferred tax assets related to loss carry-forward, investment credits and deductible temporary differences were summarized as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Loss carry-forward $ 652,593 $ 542,054 $ 18,288 Investment credits 280,068 - - Deductible temporary differences 904,441 712,141 24,026 $ 1,837,102 $ 1,254,195 $ 42,314
Summary of Unused Loss Carry-forward	As of December 31, 2017, the unused loss carry-forward comprised of: Year of Expiry NT$ US$ (Note 4) 2018 $ 230,656 $ 7,782 2019 34,981 1,180 2020 615,327 20,760 2021 164,377 5,546 2022 and thereafter 178,154 6,011 $ 1,223,495 $ 41,279
Summary of Unused Investment Credits	As of December 31, 2017, unused investment credits comprised of: Remaining Creditable Amount Tax Credit Source NT$ US$ Expiry Year (Note 4) Purchase of machinery and equipment $ 518,790 $ 17,503 2018 Others 15,423 520 2022 and thereafter $ 534,213 $ 18,023
Summary of Projects were Exempted From Income Tax	As of December 31, 2017, profits attributable to the following expansion projects were exempted from income tax for a 5-year period: Tax-exemption Period Construction and expansion of 2007 by the Company 2016.01-2020.12 Construction and expansion of 2008 by the Company 2014.01-2018.12 Construction and expansion of 2008 by ASE Test Inc. 2014.01-2018.12 Construction and expansion of 2009 by ASE Test Inc. 2018.01-2022.12 Expansion of 2008 by ASE Electronics Inc. 2016.01-2020.12

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Earnings and Weighted Average Number of Ordinary Shares Outstanding in Computation of Earnings Per Share	The earnings and weighted average number of ordinary shares outstanding in the computation of earnings per share were as follows: Net profit for the year For the Year Ended December 31 2015 2016 (Retrospectively Adjusted) 2017 NT$ NT$ NT$ US$ (Note 4) Profit for the year attributable to owners of the Company $ 19,732,148 $ 21,324,423 $ 22,819,119 $ 769,876 Effect of potentially dilutive ordinary shares: Employee share options issued by subsidiaries - (374,359 ) (813,627 ) (27,450 ) Investments in associates (210,126 ) (494,388 ) (367,687 ) (12,405 ) Convertible bonds 901,187 (1,165,506 ) 93,781 3,164 Earnings used in the computation of diluted earnings per share $ 20,423,209 $ 19,290,170 $ 21,731,586 $ 733,185 Weighted average number of ordinary shares outstanding For the Year Ended December 31 2015 2016 2017 Weighted average number of ordinary shares in computation of basic earnings per share 7,652,773 7,662,870 8,160,887 Effect of potentially dilutive ordinary shares: Convertible bonds 455,671 515,295 124,911 Employee share options 86,994 59,218 39,868 Employees’ compensation 54,626 46,746 43,574 Weighted average number of ordinary shares in computation of diluted earnings per share 8,250,064 8,284,129 8,369,240

Share-based Payment Arrangeme69

Share-based Payment Arrangements (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Inputs Related to Fair Value of Share Options	Share options granted by the Company and USISH in 2015 were measured using the Hull & White Model (2004) incorporated with Ritchken’s Trinomial Tree Model (1995) and the Black-Scholes Option Pricing Model, respectively, and the inputs to the models were as follows: ASE Inc. USISH Share price at the grant date NT$36.5 CNY15.2 Exercise prices NT$36.5 CNY15.5 Expected volatility 27.02% 40.33%-45.00% Expected lives 10 years 10 years Expected dividend yield 4.00% 0.87% Risk free interest rates 1.34% 3.06%-3.13%
ASE Inc. option plans [member]
Summary of Information About Share Options	Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (NT$) Thousands) (NT$) Thousands) (NT$) Balance at January 1 209,745 $ 20.7 252,607 $ 26.6 210,795 $ 27.3 Options granted 94,270 36.5 - - - - Options forfeited (1,975 ) 30.3 (6,056 ) 34.6 (5,407 ) 36.3 Options expired (730 ) 11.1 - - (1,790 ) 21.1 Options exercised (48,703 ) 20.6 (35,756 ) 20.9 (67,637 ) 21.0 Balance at December 31 252,607 26.6 210,795 27.3 135,961 30.2 Options exercisable, end of year 158,103 20.8 123,007 20.8 85,642 26.5 Weighted-average fair value of options granted (NT$) $ 7.18~7.39 $ - $ -
Summary of Outstanding Share Options	Information about the Company’s outstanding share options at each balance sheet date was as follows: Range of Exercise Price Per Share (NT$) Weighted Average Remaining Contractual Life (Years) December 31, 2016 4 th $ 20.4-22.6 2.5 5 th 36.5 8.7 December 31, 2017 4 th 20.4-22.6 2.5 5 th 36.5 7.7
ASE Mauritius Inc. option plan [member]
Summary of Information About Share Options	Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (US$) Thousands) (US$) Thousands) (US$) Balance at January 1 28,545 $ 1.7 28,470 $ 1.7 28,470 $ 1.7 Options forfeited (75 ) 1.7 - - (250 ) 1.7 Options expired - - - - (28,220 ) 1.7 Balance at December 31 28,470 1.7 28,470 1.7 - - Options exercisable, end of year 28,470 1.7 28,470 1.7 - -
USIE option plans [member]
Summary of Information About Share Options	Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (US$) Thousands) (US$) Thousands) (US$) Balance at January 1 34,159 $ 2.1 29,695 $ 2.1 25,933 $ 2.2 (continued) For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (US$) Thousands) (US$) Thousands) (US$) Options forfeited (84 ) $ 2.8 - $ - - $ - Options exercised (4,380 ) 1.9 (3,762 ) 2.0 (377 ) 1.9 Balance at December 31 29,695 2.1 25,933 2.2 25,556 2.2 Options exercisable, end of year 28,106 2.1 25,933 2.2 25,556 2.2
Summary of Outstanding Share Options	Information about USIE’s outstanding share options at each balance sheet date was as follows: Range of Exercise Price Per Share (US$) Weighted Average Remaining Contractual Life (Years) December 31, 2016 1 st $ 1.5 4.0 2 nd rd 2.4-2.9 3.9 December 31, 2017 1 st $ 1.5 3.0 2 nd rd 2.4-2.9 2.9
USISH option plans [member]
Summary of Information About Share Options	Information about share options was as follows: For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (CNY) Thousands) (CNY) Thousands) (CNY) Balance at December 31 - $ - 26,627 $ 15.5 24,997 $ 15.5 (continued) For the Year Ended December 31 2015 2016 2017 Weighted Weighted Weighted Average Average Average Number of Exercise Number of Exercise Number of Exercise Options Price Options Price Options Price (In Per Share (In Per Share (In Per Share Thousands) (CNY) Thousands) (CNY) Thousands) (CNY) Options granted 26,640 $ 15.5 - $ - - $ - Options forfeited (13 ) 15.5 (1,630 ) 15.5 (2,656 ) 15.5 Balance at December 31 26,627 15.5 24,997 15.5 22,341 15.5 Options exercisable, end of year - - - - 8,896 15.5 (concluded)
New shares reserved for subscription by employees under cash capital increase [member]
Summary of Information About Share Options	Information about the Company’s employee share options related to the aforementioned newly issued shares was as follows: Number of Options (In Thousand) Options granted for the year ended December 31, 2017 30,000 Options exercised for the year ended December 31, 2017 25,164 Weighted-average fair value of options granted (NT$ per share) $ 2.80
Summary of Inputs Related to Fair Value of Share Options	Fair value was measured using the Black-Scholes Option Pricing Model and the inputs to the model were as follows: Share price at the grant date NT$36.55 per share Exercise price NT$34.30 per share Expected volatility 27.15% Expected lives 47 days Expected dividend yield - Risk free interest rate 0.37%

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Subsidiary Acquired	a. Subsidiary acquired Principal Activity Date of Acquisition Proportion of Voting Equity Interests Acquired Cash Consideration NT$ TLJ Engaged in information software services May 3, 2016 60 % $ 89,998
Summary of Assets Acquired and Liabilities Assumed at the Date of Acquisition	b. Assets acquired and liabilities assumed at the date of acquisition NT$ Current assets $ 16,645 Non-current assets 108,486 Current liabilities (7,599 ) Fair value of identifiable net assets acquired $ 117,532
Summary of Goodwill Recognized on Acquisition	c. Goodwill recognized on acquisition NT$ Consideration transferred (paid in cash) $ 89,998 Add: Non-controlling interests 42,857 Less: Fair value of identifiable net assets acquired (117,532 ) Goodwill recognized on acquisition $ 15,323
Summary of Net Cash Outflow on Acquisition of Subsidiaries	d. Net cash outflow on acquisition of subsidiaries NT$ Consideration paid in cash $ 89,998 Less: Cash acquired (16,561 ) $ 73,437
Summary of Retrospective Adjustments of Intangible Assets	As of December 31, 2016, the retrospective adjustments are summarized as follows: After Retrospectively Adjusted Before Retrospectively Adjusted NT$ NT$ December 31, 2016 Goodwill $ 10,490,309 $ 10,558,878 Other intangible assets $ 1,617,261 $ 1,560,989 For the year ended December 31, 2016 Operating costs $ 221,696,922 $ 221,689,888 Operating expenses $ 26,526,815 $ 26,485,716

Disposal of Subsidiaries (Table

Disposal of Subsidiaries (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Gain on Disposal of Subsidiaries	a. Gain on disposal of subsidiaries NT$ US$ (Note 4) Total consideration $ 7,046,464 $ 237,735 Net assets disposed of (1,457,007 ) (49,157 ) Gain on disposal of KSDY $ 5,589,457 $ 188,578
Summary of Analysis of Assets and Liabilities on Date Control was Lost	b. Analysis of assets and liabilities on the date control was lost NT$ US$ (Note 4) Current assets Cash and cash equivalents $ 29,133 $ 983 Inventories related to real estate business 1,427,874 48,174 Net assets disposed of $ 1,457,007 $ 49,157

Non-cash Transactions (Tables)

Non-cash Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Non-cash Investing Activities	a. Except those discussed in Note 11, for the years ended December 31, 2015, 2016 and 2017, the Group entered into the following non-cash investing activities which were not reflected in the consolidated statements of cash flows: For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Payments for property, plant and equipment Purchase of property, plant and equipment $ 28,280,821 $ 27,680,862 $ 23,677,682 $ 798,842 Increase (decrease) in prepayments for property, plant and equipment (recorded under the line item of other non-current assets) (267,334 ) (89,337 ) 90,560 3,055 (Increase) decrease in payables for property, plant and equipment (recorded under the line item of other payables) 2,314,772 (823,171 ) 982,260 33,140 (Continued) For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Capitalized borrowing costs (48,135 ) (54,191 ) (51,262 ) (1,729 ) $ 30,280,124 $ 26,714,163 $ 24,699,240 $ 833,308 Proceeds from disposal of property, plant and equipment Consideration from disposal of property, plant and equipment $ 201,766 $ 692,826 $ 1,487,334 $ 50,180 (Increase) decrease in other receivables 41,265 (22,626 ) 876 30 $ 243,031 $ 670,200 $ 1,488,210 $ 50,210 Investment properties Purchase of investment properties $ - $ - $ 186,535 $ 6,293 Capitalized borrowing costs - - (13 ) - $ - $ - $ 186,522 $ 6,293 Payments for other intangible assets Purchase of other intangible assets $ 491,135 $ 675,144 $ 277,825 $ 9,373 Decrease (increase) in other payables - (120,938 ) 60,159 2,030 Increase in other non-current liabilities - (40,313 ) - - $ 491,135 $ 513,893 $ 337,984 $ 11,403 Net cash inflow from disposal of subsidiaries Consideration from disposal of subsidiaries $ - $ - $ 7,046,464 $ 237,735 Increase in other payables - - 3,552 120 Cash and cash equivalents disposed of - - (29,133 ) (983 ) $ - $ - $ 7,020,883 $ 236,872

Operating Lease Arrangements (T

Operating Lease Arrangements (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Future Minimum Lease Payments of Non-cancellable Operating Lease Commitments	As of December 31, 2017, the future minimum lease payments of non-cancellable operating lease commitments were as follows: NT$ US$ (Note 4) Less than 1 year $ 246,026 $ 8,300 1-5 years 439,408 14,825 More than 5 years 419,232 14,144 $ 1,104,666 $ 37,269

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Categories of Financial Instruments	December 31 2016 2017 NT$ NT$ US$ (Note 4) Financial assets FVTPL Designated as at FVTPL $ 100,583 $ 100,496 $ 3,391 Held for trading 2,969,229 5,122,571 172,826 Available-for-sale financial assets 1,295,034 1,212,165 40,896 Loans and receivables (Note 1) 92,082,628 103,973,567 3,507,881 Financial liabilities FVTPL Held for trading 1,763,660 677,430 22,855 Measured at amortized cost (Note 2) 168,397,006 139,561,999 4,708,569 Note 1: The balances included loans and receivables measured at amortized cost which comprise cash and cash equivalents, trade and other receivables and other financial assets. Note 2: The balances included financial liabilities measured at amortized cost which comprise short-term borrowings, trade and other payables, bonds payable and long-term borrowings.
Summary of Maturity Analysis for Non-derivative Financial Liabilities	On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year 1 to 5 Years More than 5 Years NT$ NT$ NT$ NT$ NT$ December 31, 2016 Non-derivative financial liabilities Non-interest bearing $ 23,907,221 $ 20,553,395 $ 4,360,322 $ 42,285 $ 190,941 Floating interest rate liabilities 9,733,727 5,232,407 6,634,931 44,504,416 1,728,448 (continued) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year 1 to 5 Years More than 5 Years NT$ NT$ NT$ NT$ NT$ Fixed interest rate liabilities $ 5,360,644 $ 1,019,221 $ 10,549,983 $ 28,553,095 $ 2,062,500 $ 39,001,592 $ 26,805,023 $ 21,545,236 $ 73,099,796 $ 3,981,889 (concluded) December 31, 2017 Non-derivative financial liabilities Non-interest bearing $ 30,695,797 $ 18,387,296 $ 4,549,468 $ 2,807 $ 176,199 Floating interest rate liabilities 6,641,541 4,153,830 5,101,178 27,196,245 900,310 Fixed interest rate liabilities 8,522,765 7,526,270 1,526,449 11,902,335 6,462,396 $ 45,860,103 $ 30,067,396 $ 11,177,095 $ 39,101,387 $ 7,538,905 On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year 1 to 5 Years More than 5 Years US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) December 31, 2017 Non-derivative financial liabilities Non-interest bearing $ 1,035,621 $ 620,354 $ 153,491 $ 95 $ 5,945 Floating interest rate liabilities 224,073 140,143 172,104 917,552 30,375 Fixed interest rate liabilities 287,543 253,923 51,500 401,563 218,029 $ 1,547,237 $ 1,014,420 $ 377,095 $ 1,319,210 $ 254,349
Summary of Maturity Analysis for Derivative Financial Instruments	On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year NT$ NT$ NT$ December 31, 2016 Net settled Forward exchange contracts $ 22,680 $ 13,320 $ - Foreign currency option contracts $ (344 ) $ - $ - Gross settled Forward exchange contracts Inflows $ 5,134,196 $ 912,213 $ - Outflows (5,245,724 ) (915,900 ) - (111,528 ) (3,687 ) - (continued) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year NT$ NT$ NT$ Swap contracts Inflows $ 5,345,159 $ 17,399,695 $ 43,537,500 Outflows (5,439,190 ) (17,540,927 ) (42,882,201 ) (94,031 ) (141,232 ) 655,299 $ (205,559 ) $ (144,919 ) $ 655,299 December 31, 2017 Net settled Forward exchange contracts $ (8,820 ) $ - $ - Gross settled Forward exchange contracts Inflows $ 3,711,302 $ 2,169,093 $ 390,379 Outflows (3,679,154 ) (2,138,635 ) (386,880 ) 32,148 30,458 3,499 Swap contracts Inflows 12,116,531 14,434,880 36,676,224 Outflows (12,189,576 ) (14,629,738 ) (36,452,898 ) (73,045 ) (194,858 ) 223,826 $ (40,897 ) $ (164,400 ) $ 227,325 (concluded) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year US$ (Note 4) US$ (Note 4) US$ (Note 4) December 31, 2017 Net settled Forward exchange contracts $ (298 ) $ - $ - (Continued) On Demand or Less than 1 Month 1 to 3 Months 3 Months to 1 Year US$ (Note 4) US$ (Note 4) US$ (Note 4) Gross settled Forward exchange contracts Inflows $ 125,213 $ 73,181 $ 13,171 Outflows (124,128 ) (72,154 ) (13,154 ) 1,085 1,027 118 Swap contracts Inflows 408,790 487,007 1,237,389 Outflows (411,254 ) (493,581 ) (1,229,838 ) (2,464 ) (6,574 ) 7,551 $ (1,379 ) $ (5,547 ) $ 7,669
Reconciliation of Liabilities Arising From Financing Activities	The table below details changes in the Group’s liabilities arising from financing activities, including both cash and non-cash changes. Liabilities arising from financing activities are those for which cash flows were, of future cash flows will be, classified in the Group’s condensed consolidated statement of cash flows as cash flows from financing activities. For the year ended December 31, 2017 Short-term borrowings Bonds payable Long-term borrowings Total NT$ NT$ NT$ NT$ Balance at January 1, 2017 $ 20,955,522 $ 36,999,903 $ 53,115,563 $ 111,070,988 Financing cash flows (2,038,993 ) (1,123,972 ) (16,473,381 ) (19,636,346 ) Non-cash changes Amortization of issuance cost - 319,463 5,790 325,253 Converted to ordinary shares in current period - (11,650,369 ) - (11,650,369 ) Effects of exchange rate changes (954,058 ) (1,402,245 ) (1,241,344 ) (3,597,647 ) Balance at December 31, 2017 $ 17,962,471 $ 23,142,780 $ 35,406,628 $ 76,511,879 Short-term borrowings Bonds payable Long-term borrowings Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) Balance at January 1,2017 $ 707,001 $ 1,248,310 $ 1,792,023 $ 3,747,334 Financing cash flows (68,792 ) (37,920 ) (555,782 ) (662,494 ) Non-cash changes Amortization of issuance cost - 10,778 195 10,973 Converted to ordinary shares in current period - (393,062 ) - (393,062 ) Effects of exchange rate changes (32,188 ) (47,310 ) (41,881 ) (121,379 ) Balance at December 31, 2017 $ 606,021 $ 780,796 $ 1,194,555 $ 2,581,372
Interest rate risk [member]
Summary of Interest Rate Risk	The carrying amounts of the Group’s financial assets and financial liabilities with exposure to interest rates at each balance sheet date were as follows: December 31 2016 2017 NT$ NT$ US$ (Note 4) Fair value interest rate risk Financial liabilities $ 30,243,887 $ 17,552,955 $ 592,205 Cash flow interest rate risk Financial assets 29,977,709 39,880,736 1,345,504 Financial liabilities 65,800,323 42,270,321 1,426,124
Fair value of financial instruments not measured at fair value but for which fair value is disclosed [member]
Summary of Fair Value of Financial Instruments	The carrying amounts and fair value of bonds payable as of December 31, 2016 and 2017, respectively, were as follows: Carrying Amount Fair Value NT$ US$ (Note 4) NT$ US$ (Note 4) December 31, 2016 $ 36,999,903 $ 37,300,356 December 31, 2017 23,142,780 $ 780,796 23,247,085 $ 784,315
Measured at fair value on a recurring basis [member]
Summary of Fair Value of Financial Instruments	1) Fair value hierarchy Level 1 Level 2 Level 3 Total NT$ NT$ NT$ NT$ December 31, 2016 Financial assets at FVTPL Financial assets designated as at FVTPL Private-placement convertible bonds $ - $ 100,583 $ - $ 100,583 Derivative financial assets Forward exchange contracts - 462,339 - 462,339 Forward currency options - 66,872 - 66,872 Non-derivative financial assets held for trading Quoted shares $ 1,855,073 $ - $ - $ 1,855,073 Open-end mutual funds 584,945 - - 584,945 $ 2,440,018 $ 629,794 $ - $ 3,069,812 Available-for-sale financial assets Unquoted shares $ - $ - $ 631,418 $ 631,418 Limited Partnership - - 273,372 273,372 Open-end mutual funds 243,458 - - 243,458 Quoted shares 146,786 - - 146,786 $ 390,244 $ - $ 904,790 $ 1,295,034 Financial liabilities at FVTPL Derivative financial liabilities Conversion option, redemption option and put option of convertible bonds $ - $ 1,213,890 $ - $ 1,213,890 Swap contracts - 422,934 - 422,934 Forward exchange contracts - 108,912 - 108,912 Foreign currency option contracts - 17,924 - 17,924 $ - $ 1,763,660 $ - $ 1,763,660 Level 1 Level 2 Level 3 Total NT$ US$ (Note 4) NT$ US$ (Note 4) NT$ US$ (Note 4) NT$ US$ (Note 4) December 31, 2017 Financial assets at FVTPL Financial assets designated as at FVTPL Private-placement convertible bonds $ - $ - $ 100,496 $ 3,391 $ - $ - $ 100,496 $ 3,391 Derivative financial assets Forward exchange contracts - - 61,325 2,069 - - 61,325 2,069 Swap contracts - - 60,538 2,042 - - 60,538 2,042 Non-derivative financial assets held for trading Quoted shares 4,410,732 148,810 - - - - 4,410,732 148,810 Open-end mutual funds 589,976 19,905 - - - - 589,976 19,905 $ 5,000,708 $ 168,715 $ 222,359 $ 7,502 $ - $ - $ 5,223,067 $ 176,217 Available-for-sale financial assets Unquoted shares $ - $ - $ - $ - $ 662,477 $ 22,350 $ 662,477 $ 22,350 Limited partnership - - - - 246,072 8,302 246,072 8,302 Quoted shares 279,791 9,440 - - - - 279,791 9,440 Open-end mutual funds 23,825 804 - - - - 23,825 804 $ 303,616 $ 10,244 $ - $ - $ 908,549 $ 30,652 $ 1,212,165 $ 40,896 Financial liabilities at FVTPL Derivative financial liabilities Swap contracts $ - $ - $ 652,107 $ 22,001 $ - $ - $ 652,107 $ 22,001 Forward exchange contracts - - 25,323 854 - - 25,323 854 $ - $ - $ 677,430 $ 22,855 $ - $ - $ 677,430 $ 22,855
Level 3 of fair value hierarchy [member]
Summary of Financial Assets Measured at Level 3 Fair Value	Reconciliations for the years ended December 31, 2015, 2016 and 2017 were as follows: For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Balance at January 1 $ 778,866 $ 741,089 $ 904,790 $ 30,526 Purchases 2,010 495,928 2,649 89 Total gain or loss In profit or loss (15,891 ) (100,734 ) 28 1 In other comprehensive income 21,195 (202,565 ) 17,284 583 Disposals (45,091 ) (28,928 ) (16,202 ) (547 ) Balance at December 31 $ 741,089 $ 904,790 $ 908,549 $ 30,652

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Compensation to Key Management Personnel	For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Short-term employee benefits $ 812,002 $ 790,460 $ 860,631 $ 29,036 Post-employment benefits 3,944 4,790 2,858 97 Share-based payments 17,937 11,547 - - $ 833,883 $ 806,797 $ 863,489 $ 29,133

Assets Pledged as Collateral 76

Assets Pledged as Collateral or for Security (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Assets Pledged as Collateral or for Security	In addition to Note 9, the following assets were provided as collateral for bank borrowings and the tariff guarantees of imported raw materials: December 31 2016 2017 NT$ NT$ US$ (Note 4) Inventories related to real estate business $ 16,813,023 $ 4,822,043 $ 162,687 Investment properties - 7,151,382 241,275 Land use rights (recorded as long-term prepayment for lease) - 6,813,751 229,884 Other financial assets (including current and non-current) 220,228 66,726 2,251 $ 17,033,251 $ 18,853,902 $ 636,097

Significant Assets and Liabil77

Significant Assets and Liabilities Denominated in Foreign Currencies (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Significant Assets and Liabilities Denominated in Foreign Currencies	The following information was aggregated by the foreign currencies other than functional currencies of the group entities and the exchange rates between foreign currencies and respective functional currencies were disclosed. The significant financial assets and financial liabilities denominated in foreign currencies were as follows: Foreign Currencies (In Thousand) Exchange Rate Carrying Amount (In Thousand) December 31, 2016 Monetary financial assets US$ $ 3,106,557 US$1=NT$32.25 $ 100,186,466 US$ 1,020,769 US$1=CNY6.9370 32,919,814 JPY 4,976,309 JPY1=NT$0.2756 1,371,471 JPY 9,277,760 JPY1=US$0.0085 2,556,951 Monetary financial liabilities US$ 3,013,288 US$1=NT$32.25 97,178,536 US$ 891,487 US$1=CNY6.9370 28,750,462 JPY 5,881,716 JPY1=NT$0.2756 1,621,001 JPY 9,543,756 JPY1=US$0.0085 2,630,259 December 31, 2017 Monetary financial assets US$ 3,065,296 US$1=NT$29.76 91,223,195 US$ 1,193,369 US$1=CNY6.5342 35,514,653 JPY 5,005,435 JPY1=NT$0.2642 1,322,436 JPY 8,113,284 JPY1=US$0.0089 2,143,530 (continued) Foreign Currencies (In Thousand) Exchange Rate Carrying Amount (In Thousand) Monetary financial liabilities US$ $ 2,902,995 US$1=NT$29.76 $ 86,393,137 US$ 1,007,629 US$1=CNY6.5342 29,987,042 JPY 5,415,677 JPY1=NT$0.2642 1,430,822 JPY 8,598,832 JPY1=US$0.0089 2,271,811
Summary of Realized and Unrealized Foreign Exchange Gain (Loss)	The significant realized and unrealized foreign exchange gain (loss) were as follows: For the Year Ended December 31 2015 2016 2017 Functional Currencies Exchange Rate Net Foreign Exchange Gain (Loss) Exchange Rate Net Foreign Exchange Gain (Loss) Exchange Rate Net Foreign Exchange Gain NT$ NT$ NT$ US$ (Note 4) NT$ $ (695,510 ) $ 1,494,044 $ 4,130,243 $ 139,347 US$ US$1=NT$32.825 136,795 US$1=NT$32.25 203,258 US$1=NT$29.76 (244,802 ) (8,259 ) CNY CNY1=NT$5.0550 (271,358 ) CNY1=NT$4.649 224,393 CNY1=NT$4.5545 (337,630 ) (11,391 ) $ (830,073 ) $ 1,921,695 $ 3,547,811 $ 119,697

Operating Segments Information

Operating Segments Information (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Segment Information	a. Segment revenues and operation results Adjustments Packaging Testing EMS Estate Others and Eliminations Total NT$ NT$ NT$ NT$ NT$ NT$ NT$ For the year ended December 31, 2015 Revenue from external customers $ 116,607,314 $ 25,191,916 $ 138,242,100 $ 1,340 $ 3,259,866 $ - $ 283,302,536 Inter-segment revenues (Note) 9,454,671 191,608 58,451,996 - 7,659,282 (75,757,557 ) - Segment revenues 126,061,985 25,383,524 196,694,096 1,340 10,919,148 - 359,060,093 Interest income 53,235 12,536 149,385 54,876 13,445 (41,393 ) 242,084 Interest expense (1,520,118 ) (5,821 ) (147,792 ) - (636,448 ) 41,393 (2,268,786 ) Depreciation and amortization (18,946,460 ) (6,516,912 ) (2,738,722 ) (24,074 ) (1,292,496 ) - (29,518,664 ) Share of the profit of associates and joint ventures 126,265 - - - - - 126,265 Impairment loss (139,397 ) - (102,389 ) - (16,343 ) - (258,129 ) Segment profit before income tax 15,479,868 6,354,140 2,874,944 (172,521 ) 475,357 - 25,011,788 Expenditures for segment assets 19,691,068 4,754,481 2,917,939 143,436 773,897 - 28,280,821 December 31, 2015 Investments accounted for using the equity method 37,122,244 - - - - - 37,122,244 Segment assets 193,323,304 42,652,569 79,997,341 30,000,273 19,013,405 - 364,986,892 For the year ended December 31, 2016 Revenue from external customers 125,282,829 27,031,750 115,395,130 3,909,580 3,264,818 - 274,884,107 Inter-segment revenues (Note) 4,929,897 243,980 47,721,424 - 9,186,359 (62,081,660 ) - Segment revenues 130,212,726 27,275,730 163,116,554 3,909,580 12,451,177 - 336,965,767 Interest income 32,499 41,405 130,659 29,131 8,166 (11,793 ) 230,067 Interest expense (1,727,127 ) (5,980 ) (44,433 ) - (451,790 ) 11,793 (2,217,537 ) Depreciation and amortization (After (18,706,891 ) (6,566,936 ) (2,759,298 ) (55,271 ) (1,382,041 ) - (29,470,437 ) Share of the profit of associates and joint ventures (After 1,513,394 (9,484 ) - - - - 1,503,910 Impairment loss (974,095 ) (4,136 ) (1,886 ) - - - (980,117 ) Segment profit before income tax 13,921,640 7,226,531 4,626,263 1,546,326 647,945 - 27,968,705 Expenditures for segment assets 17,561,135 8,247,003 906,042 114,462 852,220 - 27,680,862 December 31, 2016 Investments accounted for using the equity method (After 49,597,195 227,495 - - - - 49,824,690 Segment assets (After 200,604,111 42,962,643 73,915,639 28,468,242 11,979,941 - 357,930,576 For the year ended December 31, 2017 Revenue from external customers 126,225,119 26,157,277 133,948,016 412,863 3,697,933 - 290,441,208 Inter-segment revenues (Note) 4,911,026 184,707 47,119,404 23,943 8,359,697 (60,598,777 ) - Segment revenues 131,136,145 26,341,984 181,067,420 436,806 12,057,630 - 351,039,985 Interest income 43,744 48,532 269,640 30,441 183,824 (269,310 ) 306,871 Interest expense (1,969,562 ) (11,920 ) - (62,714 ) - 269,310 (1,774,886 ) Depreciation and amortization (19,105,457 ) (6,476,743 ) (2,133,253 ) (180,792 ) (1,308,939 ) - (29,205,184 ) Share of the profit or loss of associates and joint ventures 568,291 (42,509 ) - - - - 525,782 Impairment loss (218,214 ) (72,798 ) - - (473,869 ) - (764,881 ) Segment profit before income tax 12,065,304 6,904,067 6,883,327 5,120,301 47,664 - 31,020,663 Expenditures for segment assets 17,769,612 4,507,097 850,235 169,559 381,179 - 23,677,682 December 31, 2017 Investments accounted for using the equity method 48,566,333 187,418 - - - - 48,753,751 Segment assets 195,503,889 43,383,691 81,588,691 33,080,694 10,365,307 - 363,922,272 Adjustments Packaging Testing EMS Estate Others and Eliminations Total US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) US$ (Note 4) For the year ended December 31, 2017 Revenue from external customers $ 4,258,607 $ 882,499 $ 4,519,164 $ 13,929 $ 124,762 $ - $ 9,798,961 Inter-segment revenues (Note) 165,689 6,232 1,589,723 808 282,041 (2,044,493 ) - Segment revenues 4,424,296 888,731 6,108,887 14,737 406,803 - 11,843,454 Interest income 1,476 1,637 9,097 1,027 6,202 (9,086 ) 10,353 Interest expense (66,450 ) (402 ) - (2,116 ) - 9,086 (59,882 ) Depreciation and amortization (644,584 ) (218,514 ) (71,972 ) (6,100 ) (44,161 ) - (985,331 ) Share of the profit or loss of associates and joint ventures 19,173 (1,434 ) - - - - 17,739 Impairment loss (7,362 ) (2,456 ) - - (15,988 ) - (25,806 ) Segment profit before income tax 407,061 232,931 232,231 172,750 1,608 - 1,046,581 Expenditures for segment assets 599,515 152,061 28,685 5,721 12,860 - 798,842 December 31, 2017 Investments accounted for using the equity method 1,638,540 6,323 - - - - 1,644,863 Segment assets 6,595,947 1,463,687 2,752,655 1,116,083 349,707 - 12,278,079 Note: Inter-segment revenues were eliminated upon consolidation.
Summary of Revenue from Major Products and Services	b. Revenue from major products and services For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) Packaging service $ 116,607,314 $ 125,282,829 $ 126,225,119 $ 4,258,607 Testing service 25,191,916 27,031,750 26,157,277 882,499 Electronic components manufacturing service 138,242,100 115,395,130 133,948,016 4,519,164 Others 3,261,206 7,174,398 4,110,796 138,691 $ 283,302,536 $ 274,884,107 $ 290,441,208 $ 9,798,961
Summary of Geographical Information	1) Net revenues from external customers For the Year Ended December 31 2015 2016 2017 NT$ NT$ NT$ US$ (Note 4) United States $ 205,730,670 $ 180,745,837 $ 196,462,345 $ 6,628,284 Taiwan 32,631,149 38,868,679 35,413,647 1,194,792 Asia 22,885,128 29,896,304 30,201,332 1,018,938 Europe 20,577,069 23,275,732 26,445,240 892,215 Others 1,478,520 2,097,555 1,918,644 64,732 $ 283,302,536 $ 274,884,107 $ 290,441,208 $ 9,798,961 2) Noncurrent assets, excluding financial instruments, post-employment benefit assets and deferred tax assets December 31 2016 2017 NT$ NT$ US$ (Note 4) Taiwan $ 97,337,094 $ 93,350,839 $ 3,149,489 China 34,142,577 45,376,164 1,530,910 Others 26,935,370 25,025,498 844,315 $ 158,415,041 $ 163,752,501 $ 5,524,714

Application of New and Revise79

Application of New and Revised International Financial Reporting Standards as Issued by the International Accounting Standards Board ("IASB") ( Collectively, "IFRSs") - Schedule of Anticipated Impact on Assets, Liabilities and Equity Of Retrospective Application of the Requirements for the Classification, Measurement and Impairment of Financial Assets (Detail) $ in Thousands, $ in Thousands	Jan. 01, 2018TWD ($)	Jan. 01, 2018USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss - current			$ 5,223,067	$ 176,217	$ 3,069,812
Inventories			24,260,911	818,519	21,438,062
Available-for-sale financial assets - current			89,159	3,008	266,696
Investments accounted for using the equity method			48,753,751	1,644,863	49,824,690	$ 37,122,244
Deferred tax assets			4,001,821	135,014	4,536,924
Available-for-sale financial assets - non-current			1,123,006	37,888	1,028,338
Other financial assets-non-current			1,170,500	39,491	1,320,381
TOTAL			363,922,272	12,278,079	357,930,576	364,986,892
Current tax liabilities			7,619,328	257,062	6,846,350
Deferred tax liabilities			4,961,487	167,392	4,856,549
Total effect on liabilities			162,612,085	5,486,237	191,089,411
Retained earnings			73,718,545	2,487,131	62,139,524
NON-CONTROLLING INTERESTS			13,190,129	445,011	12,000,551
Unrealized gain on debt investments at fair value through other comprehensive income			214,022	7,221	214,022
Total effect on equity			201,310,187	6,791,842	$ 166,841,165	$ 165,924,980	$ 155,691,394
IFRS9 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss - current			5,223,067	176,217
Available-for-sale financial assets - current			89,159	3,008
Investments accounted for using the equity method			48,753,751	1,644,863
Available-for-sale financial assets - non-current			1,123,006	37,888
Other financial assets-non-current			1,170,500	39,491
TOTAL			56,359,483	1,901,467
Retained earnings			73,718,545	2,487,131
Unrealized gain on available-for-sale financial assets			422,570	14,257
Total effect on equity			74,141,115	2,501,388
Adoption of IFRS 15 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Inventories			24,260,911	818,519
Investments accounted for using the equity method			48,753,751	1,644,863
Deferred tax assets			4,001,821	135,014
TOTAL			77,016,483	2,598,396
Current tax liabilities			7,619,328	257,062
Deferred tax liabilities			4,961,487	167,392
Total effect on liabilities			12,580,815	424,454
Retained earnings			73,718,545	2,487,131
NON-CONTROLLING INTERESTS			13,190,129	445,011
Total effect on equity			$ 86,908,674	$ 2,932,142
Subsequent Event [Member] | IFRS9 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss - current	$ 5,312,226	$ 179,225
Investments accounted for using the equity method	48,751,165	1,644,776
Financial assets at fair value through profit or loss - non-current	214,457	7,235
Financial assets at fair value through other comprehensive income - non-current	1,988,549	67,090
Other financial assets-non-current	170,500	5,753
TOTAL	56,436,897	1,904,079
Retained earnings	74,083,012	2,499,428
Unrealized gain on equity investments at fair value through other comprehensive income	55,517	1,873
Unrealized gain on debt investments at fair value through other comprehensive income	80,000	2,699
Total effect on equity	74,218,529	2,504,000
Subsequent Event [Member] | Adoption of IFRS 15 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Inventories	22,879,133	771,900
Contract assets - current	1,971,107	66,502
Investments accounted for using the equity method	48,793,890	1,646,217
Deferred tax assets	3,994,534	134,768
TOTAL	77,638,664	2,619,387
Current tax liabilities	7,624,406	257,233
Deferred tax liabilities	5,051,558	170,431
Total effect on liabilities	12,675,964	427,664
Retained earnings	74,240,394	2,504,737
NON-CONTROLLING INTERESTS	13,195,312	445,186
Total effect on equity	87,435,706	2,949,923
Subsequent Event [Member] | Adjustments arising from initial application [member] | IFRS9 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss - current	89,159	3,008
Available-for-sale financial assets - current	(89,159)	(3,008)
Investments accounted for using the equity method	(2,586)	(87)
Financial assets at fair value through profit or loss - non-current	214,457	7,235
Financial assets at fair value through other comprehensive income - non-current	1,988,549	67,090
Available-for-sale financial assets - non-current	(1,123,006)	(37,888)
Other financial assets-non-current	(1,000,000)	(33,738)
TOTAL	77,414	2,612
Retained earnings	364,467	12,297
Unrealized gain on equity investments at fair value through other comprehensive income	55,517	1,873
Unrealized gain on available-for-sale financial assets	(422,570)	(14,257)
Unrealized gain on debt investments at fair value through other comprehensive income	80,000	2,699
Total effect on equity	77,414	2,612
Subsequent Event [Member] | Adjustments arising from initial application [member] | Adoption of IFRS 15 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Inventories	(1,381,778)	(46,619)
Contract assets - current	1,971,107	66,502
Investments accounted for using the equity method	40,139	1,354
Deferred tax assets	(7,287)	(246)
TOTAL	622,181	20,991
Current tax liabilities	5,078	171
Deferred tax liabilities	90,071	3,039
Total effect on liabilities	95,149	3,210
Retained earnings	521,849	17,606
NON-CONTROLLING INTERESTS	5,183	175
Total effect on equity	$ 527,032	$ 17,781

Summary of Significant Accoun80

Summary of Significant Accounting Policies - Summary of Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
A.S.E. Holding Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Bermuda
Percentage of Ownership (%)	100.00%	100.00%
J & R Holding Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Bermuda
Percentage of Ownership (%)	100.00%	100.00%
Innosource Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	100.00%	100.00%
Omniquest Industrial Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	100.00%	100.00%
ASE Marketing & Service Japan Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in marketing and sales services
Establishment and Operating Location	Japan
Percentage of Ownership (%)	100.00%	100.00%
ASE Test, Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the testing of semiconductors
Establishment and Operating Location	Kaohsiung, ROC
Percentage of Ownership (%)	100.00%	100.00%
USI [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in investing activity
Establishment and Operating Location	Nantou, ROC
Percentage of Ownership (%)	99.20%	99.20%
Luchu development corporation [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the development of real estate properties
Establishment and Operating Location	Taipei, ROC
Percentage of Ownership (%)	86.10%	86.10%
TLJ Intertech Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in information software services
Establishment and Operating Location	Taipei, ROC
Percentage of Ownership (%)	60.00%	60.00%
Alto Enterprises Limited [Member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	100.00%	100.00%
Super Zone Holdings Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Hong Kong
Percentage of Ownership (%)	100.00%	100.00%
ASE (Kun Shan) Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Kun Shan, China
Percentage of Ownership (%)	100.00%	100.00%
ASE Investment (Kun Shan) Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Kun Shan, China
Percentage of Ownership (%)	100.00%	100.00%
Advanced Semiconductor Engineering (China) Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Will engage in the packaging and testing of semiconductors
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
ASE Investment (Labuan) Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Malaysia
Percentage of Ownership (%)	100.00%	100.00%
ASE Test Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Singapore
Percentage of Ownership (%)	100.00%	100.00%
ASE (Korea) Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Korea
Percentage of Ownership (%)	100.00%	100.00%
J&R Industrial Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in leasing equipment and investing activity
Establishment and Operating Location	Kaohsiung, ROC
Percentage of Ownership (%)	100.00%	100.00%
ASE Japan Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Japan
Percentage of Ownership (%)	100.00%	100.00%
ASE (U.S.) Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	After-sales service and sales support
Establishment and Operating Location	U.S.A.
Percentage of Ownership (%)	100.00%	100.00%
Global Advanced Packaging Technology Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Cayman Islands
Percentage of Ownership (%)	100.00%	100.00%
ASE WeiHai Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Shandong, China
Percentage of Ownership (%)	100.00%	100.00%
Suzhou ASEN Semiconductors Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Suzhou, China
Percentage of Ownership (%)	60.00%	60.00%
Anstock Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in financing activity
Establishment and Operating Location	British Cayman Islands
Percentage of Ownership (%)	100.00%	100.00%
Anstock II Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in financing activity
Establishment and Operating Location	British Cayman Islands
Percentage of Ownership (%)	100.00%	100.00%
ASE Module (Shanghai) Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Absorbed by ASE (Shanghai) Inc. in February 2017
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)		100.00%
ASE (Shanghai) Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the production of substrates
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
ASE Corporation [Member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Cayman Islands
Percentage of Ownership (%)	100.00%	100.00%
ASE Mauritius Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Mauritius
Percentage of Ownership (%)	100.00%	100.00%
ASE Labuan Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Malaysia
Percentage of Ownership (%)	100.00%	100.00%
Shanghai Ding Hui Real Estate Development Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the development, construction and sale of real estate properties
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
Shanghai Ding Qi Property Management Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the management of real estate properties
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
Advanced Semiconductor Engineering (HK) Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the trading of substrates
Establishment and Operating Location	Hong Kong
Percentage of Ownership (%)	100.00%	100.00%
Shanghai Ding Wei Real Estate Development Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the development, construction and leasing of real estate properties
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
Shanghai Ding Yu Real Estate Development Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the development, construction and leasing of real estate properties
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
Shanghai Ding Fan Department Store Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in department store business
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
Kun Shan Ding Yue Real Estate Development Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the development, construction and leasing of real estate properties and was disposed of in June 2017(Note 29)
Establishment and Operating Location	Kun Shan, China
Percentage of Ownership (%)		100.00%
Kun Shan Ding Hong Real Estate Development Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the development, construction and leasing of real estate properties
Establishment and Operating Location	Kun Shan, China
Percentage of Ownership (%)	100.00%	100.00%
Shanghai Ding Xu Property Management Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the management of real estate properties, and was established in August 2017
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%
ASE Electronics Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the production of substrates
Establishment and Operating Location	Kaohsiung, ROC
Percentage of Ownership (%)	100.00%	100.00%
ASE Test Holdings, Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Cayman Islands
Percentage of Ownership (%)	100.00%	100.00%
ASE Holdings (Singapore) Pte. Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Singapore
Percentage of Ownership (%)	100.00%	100.00%
ASE Singapore Pte. Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Singapore
Percentage of Ownership (%)	100.00%	100.00%
ISE Labs, Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the testing of semiconductors
Establishment and Operating Location	U.S.A.
Percentage of Ownership (%)	100.00%	100.00%
ASE Electronics (M) Sdn. Bhd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Malaysia
Percentage of Ownership (%)	100.00%	100.00%
ASE Assembly & Test (Shanghai) Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
ASE Trading (Shanghai) Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in trading activity
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	100.00%	100.00%
Wuxi Tongzhi Microelectronics Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the packaging and testing of semiconductors
Establishment and Operating Location	Wuxi, China
Percentage of Ownership (%)	100.00%	100.00%
Huntington Holdings International Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	99.20%	99.20%
Unitech Holdings International Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	99.20%	99.20%
Real Tech Holdings Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	99.20%	99.20%
Universal ABIT Holding Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	In the process of liquidation
Establishment and Operating Location	British Cayman Islands
Percentage of Ownership (%)	99.20%	99.20%
Rising Capital Investment Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	99.20%	99.20%
Rise Accord Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	British Virgin Islands
Percentage of Ownership (%)	99.20%	99.20%
Universal Scientific Industrial (Kunshan) Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the manufacturing and sale of computer assistance system and related peripherals
Establishment and Operating Location	Kun Shan, China
Percentage of Ownership (%)	99.20%	99.20%
USI Enterprise Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the services of investment advisory and warehousing management
Establishment and Operating Location	Hong Kong
Percentage of Ownership (%)	96.90%	97.00%
USISH [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the designing, manufacturing and sale of electronic components
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	75.80%	75.90%
Universal Global Technology Co., Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Holding company
Establishment and Operating Location	Hong Kong
Percentage of Ownership (%)	75.80%	75.90%
Universal Global Technology (Kunshan) Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the designing and manufacturing of electronic components
Establishment and Operating Location	Kun Shan, China
Percentage of Ownership (%)	75.80%	75.90%
Universal Global Technology (Shanghai) Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the processing and sales of computer and communication peripherals as well as business in import and export of goods and technology
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	75.80%	75.90%
Universal Global Electronics (Shanghai) Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the sale of electronic components and telecommunications equipment
Establishment and Operating Location	Shanghai, China
Percentage of Ownership (%)	75.80%	75.90%
Universal Global Industrial Co., Limited [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in manufacturing, trading and investing activity
Establishment and Operating Location	Hong Kong
Percentage of Ownership (%)	75.80%	75.90%
Universal Global Scientific Industrial Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the manufacturing of components of telecomm and cars and provision of related R&D services
Establishment and Operating Location	Nantou, ROC
Percentage of Ownership (%)	75.80%	75.90%
USI America Inc. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the manufacturing and processing of motherboards and wireless network communication and provision of related technical service.
Establishment and Operating Location	U.S.A.
Percentage of Ownership (%)	75.80%	75.90%
Universal Scientific Industrial De Mexico S.A. De C.V. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the assembling of motherboards and computer components
Establishment and Operating Location	Mexico
Percentage of Ownership (%)	75.80%	75.90%
USI Japan Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the manufacturing and sale of computer peripherals, integrated chip and other related accessories
Establishment and Operating Location	Japan
Percentage of Ownership (%)	75.80%	75.90%
USI Electronics (Shenzhen) Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the design, manufacturing and sale of motherboards and computer peripherals
Establishment and Operating Location	Shenzhen, China
Percentage of Ownership (%)	75.80%	75.90%
Universal Scientific Industrial Co., Ltd. [member]
Disclosure of subsidiaries [Line Items]
Main Business	Engaged in the manufacturing, processing and sale of computers, computer peripherals and related accessories
Establishment and Operating Location	Nantou, ROC
Percentage of Ownership (%)	75.50%	75.20%

Summary of Significant Accoun81

Summary of Significant Accounting Policies - Additional Information (Detail) - $ / $	1 Months Ended	12 Months Ended
	Feb. 28, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Abstract]
Income tax on unappropriated earnings	5.00%	10.00%
Convenience exchange rate		29.64

Cash and Cash Equivalents - Sum

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Cash and cash equivalents [abstract]
Cash on hand	$ 8,404	$ 284	$ 6,856
Checking accounts and demand deposits	39,697,319	1,339,316	28,823,763
Cash equivalents	6,372,343	214,991	9,561,905
Cash and cash equivalents,total	$ 46,078,066	$ 1,554,591	$ 38,392,524	$ 1,295,294	$ 55,251,181	$ 51,694,410

Financial Instruments at Fair83

Financial Instruments at Fair Value Through Profit or Loss - Summary of Financial Instruments at Fair Value Through Profit or Loss (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about financial instruments [line items]
Financial assets designated as at FVTPL	$ 100,496	$ 3,391	$ 100,583
Financial assets held for trading	5,122,571	172,826	2,969,229
Current financial assets at fair value through profit or loss	5,223,067	176,217	3,069,812
Financial liabilities held for trading	677,430	22,855	1,763,660
Private-placement convertible bonds [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets designated as at FVTPL	100,496	3,391	100,583
Quoted shares [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	4,410,732	148,810	1,855,073
Open-end mutual funds [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	589,976	19,905	584,945
Forward Exchange Contracts [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	61,325	2,069	66,872
Swap contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	60,538	2,042	462,339
Financial liabilities held for trading	652,107	22,001	422,934
Forward exchange contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	61,325	2,069	462,339
Financial liabilities held for trading	$ 25,323	$ 854	108,912
Conversion option, redemption option and put option of convertible bonds [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities held for trading			1,213,890
Foreign currency option contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading			66,872
Financial liabilities held for trading			$ 17,924

Financial Instruments at Fair84

Financial Instruments at Fair Value Through Profit or Loss - Summary of Outstanding Contracts Not Accounted for Hedge Accounting (Detail) € in Thousands, ₩ in Thousands, ¥ in Thousands, ¥ in Thousands, RM in Thousands, $ in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2017JPY (¥)	Dec. 31, 2017MYR (RM)	Dec. 31, 2017SGD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2016USD ($)	Dec. 31, 2016CNY (¥)	Dec. 31, 2016JPY (¥)	Dec. 31, 2016KRW (₩)	Dec. 31, 2016MYR (RM)	Dec. 31, 2016SGD ($)	Dec. 31, 2016EUR (€)
Swap contracts [member] | Sell NT$/buy US$ [member]
Disclosure of detailed information about financial instruments [line items]
Notional Amount	$ 53,136,302	$ 59,797,499	$ 1,782,400						$ 1,871,000
Swap contracts [member] | Sell NT$/buy US$ [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Swap contracts [member] | Sell NT$/buy US$ [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-12	2017-12
Swap contracts [member] | Sell US$/buy CNY [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-03
Notional Amount			52,948	¥ 349,800					49,904	¥ 349,800
Swap contracts [member] | Sell US$/buy JPY [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-02
Notional Amount			70,324		¥ 7,870,000				77,153		¥ 8,600,000
Swap contracts [member] | Sell US$/buy JPY [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-02
Swap contracts [member] | Sell US$/buy JPY [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-03
Swap contracts [member] | Sell US$/buy NT$ [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Notional Amount	$ 6,505,767	$ 1,958,908	217,300						61,000
Forward exchange contracts [member] | Sell NT$/buy US$ [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01
Notional Amount	$ 2,389,620	$ 2,842,330	80,000						90,000
Forward exchange contracts [member] | Sell NT$/buy US$ [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-01
Forward exchange contracts [member] | Sell NT$/buy US$ [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-02
Forward exchange contracts [member] | Sell US$/buy CNY [member]
Disclosure of detailed information about financial instruments [line items]
Notional Amount			125,000	¥ 828,858					70,000	484,805
Forward exchange contracts [member] | Sell US$/buy CNY [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Forward exchange contracts [member] | Sell US$/buy CNY [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-04	2017-02
Forward exchange contracts [member] | Sell US$/buy JPY [member]
Disclosure of detailed information about financial instruments [line items]
Notional Amount			45,517		¥ 5,111,101				43,877		¥ 5,063,820
Forward exchange contracts [member] | Sell US$/buy JPY [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Forward exchange contracts [member] | Sell US$/buy JPY [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-02	2017-02
Forward exchange contracts [member] | Sell US$/Buy KRW [Member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-01
Notional Amount									35,000			₩ 41,012,700
Forward exchange contracts [member] | Sell US$/Buy MYR [Member]
Disclosure of detailed information about financial instruments [line items]
Notional Amount			15,000			RM 61,859			19,000				RM 84,544
Forward exchange contracts [member] | Sell US$/Buy MYR [Member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Forward exchange contracts [member] | Sell US$/Buy MYR [Member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-03	2017-02
Forward exchange contracts [member] | Sell US$/buy NT$ [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01
Notional Amount	$ 30,142	$ 6,099,400	1,000						190,000
Forward exchange contracts [member] | Sell US$/buy NT$ [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-01
Forward exchange contracts [member] | Sell US$/buy NT$ [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-03
Forward exchange contracts [member] | Sell US$/Buy SGD [Member]
Disclosure of detailed information about financial instruments [line items]
Notional Amount			11,300				$ 15,305		12,900					$ 18,080
Forward exchange contracts [member] | Sell US$/Buy SGD [Member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Forward exchange contracts [member] | Sell US$/Buy SGD [Member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-02	2017-03
Forward exchange contracts [member] | Sell US$/Buy EUR [Member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period	2018-01	2017-01
Notional Amount			$ 10,674					€ 9,000	281						€ 270
Foreign currency option contracts [member] | Buy US$ Call/CNY put [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-08
Notional Amount									2,000	13,800
Foreign currency option contracts [member] | Buy US$ Put/CNY call [member]
Disclosure of detailed information about financial instruments [line items]
Maturity Period		2017-08
Notional Amount									$ 1,000	¥ 6,900

Available-for-sale Financial 85

Available-for-sale Financial Assets - Summary of Available-for-sale Financial Assets (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	$ 1,212,165	$ 40,896	$ 1,295,034
Current	89,159	3,008	266,696
Non-current	1,123,006	37,888	1,028,338
Unquoted ordinary shares [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	605,110	20,415	553,350
Quoted ordinary shares [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	279,791	9,440	146,786
Limited partnership [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	246,072	8,302	273,372
Unquoted preferred shares [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	57,367	1,935	78,068
Open-end mutual funds [member]
Disclosure of financial assets [Line Items]
Available-for-sale financial assets	$ 23,825	$ 804	$ 243,458

Trade Receivables, Net - Summar

Trade Receivables, Net - Summary of Trade Receivables, Net (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets [Line Items]
Trade receivables	$ 55,200,706	$ 1,862,372	$ 51,145,557
Cost [member]
Disclosure of financial assets [Line Items]
Trade receivables	55,265,607	1,864,562	51,199,266
Allowance for doubtful debts [member]
Disclosure of financial assets [Line Items]
Trade receivables	$ 64,901	$ 2,190	$ 53,709

Trade Receivables, Net - Additi

Trade Receivables, Net - Additional Information (Detail) - Customers	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [Line Items]
Number of largest customers	5	5
Percentage of accounts receivable from largest customers	33.00%	30.00%
Bottom of range [member]
Disclosure of financial assets [Line Items]
Average credit terms	30 days
Top of range [member]
Disclosure of financial assets [Line Items]
Average credit terms	90 days

Trade Receivables, Net - Summ88

Trade Receivables, Net - Summary of Aging of Receivables Based on Past Due Date (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets [Line Items]
Trade receivables	$ 55,200,706	$ 1,862,372	$ 51,145,557
Cost [member]
Disclosure of financial assets [Line Items]
Trade receivables	55,265,607	1,864,562	51,199,266
Cost [member] | Not past due [member]
Disclosure of financial assets [Line Items]
Trade receivables	49,599,512	1,673,398	45,959,876
Cost [member] | Less than 1 month [member]
Disclosure of financial assets [Line Items]
Trade receivables	4,986,491	168,235	4,467,435
Cost [member] | 1 to 3 months [member]
Disclosure of financial assets [Line Items]
Trade receivables	562,200	18,968	700,122
Cost [member] | More than 91 days [member]
Disclosure of financial assets [Line Items]
Trade receivables	$ 117,404	$ 3,961	$ 71,833

Trade Receivables, Net - Summ89

Trade Receivables, Net - Summary of Aging of Receivables Past Due but Not Impaired (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets that are either past due or impaired [line items]
Trade receivables	$ 55,200,706	$ 1,862,372	$ 51,145,557
Past due but not impaired [member]
Disclosure of financial assets that are either past due or impaired [line items]
Trade receivables	5,321,203	179,528	5,046,126
Past due but not impaired [member] | 1 to 30 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Trade receivables	4,942,677	166,757	4,449,479
Past due but not impaired [member] | 1 to 3 months [member]
Disclosure of financial assets that are either past due or impaired [line items]
Trade receivables	$ 378,526	$ 12,771	$ 596,647

Trade Receivables, Net - Summ90

Trade Receivables, Net - Summary of Movement of Allowance for Doubtful Trade Receivables (Detail) - Trade receivables [member] $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of financial assets [Line Items]
Beginning balance	$ 53,709	$ 1,812	$ 82,906	$ 84,145
Impairment losses recognized	13,629	460	(28,022)	8,232
Amount written off	(34)	(1)		(7,826)
Effect of foreign currency exchange differences	(2,403)	(81)	(1,175)	(1,645)
Ending balance	64,901	2,190	53,709	82,906
Impaired individually [member]
Disclosure of financial assets [Line Items]
Beginning balance	16,453	555	39,046	28,305
Impairment losses recognized	9,527	322	(21,501)	18,816
Amount written off				(7,617)
Effect of foreign currency exchange differences	(850)	(29)	(1,092)	(458)
Ending balance	25,130	848	16,453	39,046
Impaired collectively [member]
Disclosure of financial assets [Line Items]
Beginning balance	37,256	1,257	43,860	55,840
Impairment losses recognized	4,102	138	(6,521)	(10,584)
Amount written off	(34)	(1)		(209)
Effect of foreign currency exchange differences	(1,553)	(52)	(83)	(1,187)
Ending balance	$ 39,771	$ 1,342	$ 37,256	$ 43,860

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Classes of current inventories [abstract]
Finished goods	$ 6,740,816	$ 227,423	$ 6,519,465
Work in process	3,452,332	116,475	2,822,687
Raw materials	12,625,502	425,962	10,850,062
Supplies	894,196	30,168	795,093
Raw materials and supplies in transit	548,065	18,491	450,755
Inventories	$ 24,260,911	$ 818,519	$ 21,438,062

Inventories - Additional Inform

Inventories - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Classes of current inventories [abstract]
Cost of inventories recognized as operating costs	$ 237,193,286	$ 8,002,473	$ 219,630,270	$ 233,165,722
Write-downs of inventories	$ 398,824	$ 13,456	$ 451,780	$ 352,011

Inventories Related to Real E93

Inventories Related to Real Estate Business - Summary of Inventories Related to Real Estate Business (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Inventories related to real estate business	$ 9,819,516	$ 331,293	$ 24,187,515
Land and buildings held for sale [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Inventories related to real estate business	25,825	871	263,526
Construction in progress and machinery in transit [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Inventories related to real estate business	8,106,166	273,488	22,236,464
Land held for construction [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Inventories related to real estate business	$ 1,687,525	$ 56,934	$ 1,687,525

Inventories Related to Real E94

Inventories Related to Real Estate Business - Additional Information (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Investment properties	$ 8,119,436	$ 273,935
Inventories related to real estate business expected to be recovered longer than twelve months	9,818,869	331,271	$ 12,076,154
Reclassified of buildings and land use right under the line item of "inventories related to real estate - construction in progress" [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Investment properties	6,971,372	235,201
Long-term prepayments for lease	$ 5,798,449	$ 195,629

Other Financial Assets - Summar

Other Financial Assets - Summary of Other Financial Assets (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets [Line Items]
Other financial assets	$ 1,642,840	$ 55,427	$ 1,879,067
Current	472,340	15,936	558,686
Non-current	1,170,500	39,491	1,320,381
Unsecured subordinate corporate bonds [member]
Disclosure of financial assets [Line Items]
Other financial assets	1,000,000	33,738	1,000,000
Time deposits with original maturity of over three months [member]
Disclosure of financial assets [Line Items]
Other financial assets	405,520	13,682	480,736
Pledged time deposits [member]
Disclosure of financial assets [Line Items]
Other financial assets	59,456	2,006	206,530
Guaranty deposits [member]
Disclosure of financial assets [Line Items]
Other financial assets	170,594	5,756	178,103
Others [member]
Disclosure of financial assets [Line Items]
Other financial assets	$ 7,270	$ 245	$ 13,698

Other Financial Assets - Additi

Other Financial Assets - Additional Information (Detail)	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets [abstract]
Corporate bonds annual interest rate	3.50%	3.50%

Investments Accounted for Usi97

Investments Accounted for Using the Equity Method - Summary of Investments Accounted for Using the Equity Method (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Investments in subsidiaries, joint ventures and associates [abstract]
Investments in associates	$ 48,267,237	$ 1,628,449	$ 49,154,140
Investments in joint venture	486,514	16,414	670,550
Investments accounted for using the equity method	$ 48,753,751	$ 1,644,863	$ 49,824,690	$ 37,122,244

Investments Accounted for Usi98

Investments Accounted for Using the Equity Method - Summary of Investments in Associates Accounted for Using the Equity Method (Detail) $ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2016	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2017USD ($)
Disclosure of associates and joint ventures [line items]
Investments in associates		$ 48,267,237	$ 49,154,140	$ 1,628,449
Siliconware Precision Industries Co., Ltd. [member]
Disclosure of associates and joint ventures [line items]
Main Business		Engaged in assembly, testing and turnkey services of integrated circuits
Operating Location		ROC
Percentages of ownership held by the Group		33.29%	33.29%
Deca Technologies Inc. [member]
Disclosure of associates and joint ventures [line items]
Main Business		Holding company and the group engaged in manufacturing, development and marketing of wafer level packaging and interconnect technology
Operating Location		British Cayman Islands
Investments in associates			$ 1,813,677
Percentages of ownership held by the Group	22.07%	22.04%	22.07%
Hung Ching Development & Construction Co. [member]
Disclosure of associates and joint ventures [line items]
Main Business		Engaged in the development, construction and leasing of real estate properties
Operating Location		ROC
Percentages of ownership held by the Group		26.22%	26.22%
Hung Ching Kwan Co. [member]
Disclosure of associates and joint ventures [line items]
Main Business		Engaged in the leasing of real estate properties
Operating Location		ROC
Percentages of ownership held by the Group		27.31%	27.31%
Advanced Microelectronic Products Inc. [member]
Disclosure of associates and joint ventures [line items]
Main Business		Engaged in integrated circuit
Operating Location		ROC
Investments in associates			$ 264,434
Percentages of ownership held by the Group		38.76%	38.76%
Cost [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		$ 48,567,386	$ 49,454,289	1,638,576
Cost [member] | Siliconware Precision Industries Co., Ltd. [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		45,210,371	45,898,225	1,525,316
Cost [member] | Deca Technologies Inc. [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		1,583,124	1,813,677	53,412
Cost [member] | Hung Ching Development & Construction Co. [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		1,248,711	1,156,833	42,129
Cost [member] | Hung Ching Kwan Co. [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		309,630	321,120	10,447
Cost [member] | Advanced Microelectronic Products Inc. [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		215,550	264,434	7,272
Deferred gain on transfer of land [member]
Disclosure of associates and joint ventures [line items]
Investments in associates		$ 300,149	$ 300,149	$ 10,127

Investments Accounted for Usi99

Investments Accounted for Using the Equity Method - Additional Information (Detail) $ / shares in Units, $ in Thousands, $ in Thousands	1 Months Ended			12 Months Ended
	Nov. 30, 2016TWD ($)shares	Jul. 31, 2016TWD ($)shares	Jul. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016TWD ($)
ASE Test, Inc. [member]
Disclosure of Investments Accounted for Using Equity Method [line Items]
Percentage of ownership				100.00%	100.00%
ASE Test, Inc. [member] | Advanced Microelectronic Products Inc. [member]
Disclosure of Investments Accounted for Using Equity Method [line Items]
Preferred shares acquired | shares	90,000,000
Consideration paid in cash for shares | $	$ 225,000
Advanced Microelectronic Products Inc. [member]
Disclosure of Investments Accounted for Using Equity Method [line Items]
Percentage of ownership	38.76%
ASE Embedded Electronics Inc. [member]
Disclosure of Investments Accounted for Using Equity Method [line Items]
Increase in capital | $						$ 146,903
Percentage of ownership interest in joint venture				51.00%	51.00%
Deca Technologies Inc. [member]
Disclosure of Investments Accounted for Using Equity Method [line Items]
Preferred shares acquired | shares		98,490,000	98,490,000
Preferred shares issued per share | $ / shares			$ 0.608
Consideration paid in cash for shares		$ 1,934,062	$ 59,882
Percentage of ownership interest in associate		22.07%	22.07%	22.04%	22.07%

Investments Accounted for Us100

Investments Accounted for Using the Equity Method - Summary of Retrospective Adjustments (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of associates and joint ventures [line items]
Investments accounted for using the equity method	$ 48,267,237	$ 1,628,449	$ 49,154,140
Deca Technologies Inc. [member]
Disclosure of associates and joint ventures [line items]
Investments accounted for using the equity method			1,813,677
Deca Technologies Inc. [member] | Previously stated [member]
Disclosure of associates and joint ventures [line items]
Investments accounted for using the equity method			1,820,329
Advanced Microelectronic Products Inc. [member]
Disclosure of associates and joint ventures [line items]
Investments accounted for using the equity method			264,434
Advanced Microelectronic Products Inc. [member] | Previously stated [member]
Disclosure of associates and joint ventures [line items]
Investments accounted for using the equity method			$ 266,085

Investments Accounted for Us101

Investments Accounted for Using the Equity Method - Summary of Fair Values of Investments in Associates with Available Published Price Quotation (Detail) - Level 1 of fair value hierarchy [member] $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Siliconware Precision Industries Co., Ltd. [member]
Disclosure of associates and joint ventures [line items]
Fair value of investments in associates with available published price quotation	$ 52,176,190	$ 1,760,330	$ 49,634,805
Hung Ching Development & Construction Co. [member]
Disclosure of associates and joint ventures [line items]
Fair value of investments in associates with available published price quotation	1,695,156	57,191	1,310,829
Advanced Microelectronic Products Inc. [member]
Disclosure of associates and joint ventures [line items]
Fair value of investments in associates with available published price quotation	$ 468,572	$ 15,809	$ 307,038

Investments Accounted for Us102

Investments Accounted for Using the Equity Method - Summarized Financial Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2014TWD ($)
Disclosure of associates and joint ventures [line items]
Current assets	$ 144,938,272		$ 142,789,659		$ 4,889,955
Non-current assets	218,984,000		215,140,917		7,388,124
Current liabilities	(108,376,737)		(106,969,574)		(3,656,434)
Non-current liabilities	(54,235,348)		(84,119,837)		(1,829,803)
Equity	201,310,187		166,841,165	$ 165,924,980	6,791,842		$ 155,691,394
Goodwill	9,934,494		10,490,309	10,506,519	335,172	$ 353,924	10,445,415
Carrying amount	48,267,237		49,154,140		1,628,449
Operating revenue	290,441,208	$ 9,798,961	274,884,107	283,302,536
Gross profit	52,732,271	1,779,091	53,187,185	50,135,228
Profit before income tax	31,020,663	1,046,581	27,968,705	25,011,788
Net profit for the year	24,497,060	826,487	22,577,861	20,700,715
Other comprehensive income (loss) for the year	(4,637,933)	(156,475)	(7,959,259)	(147,547)
Total comprehensive income for the year	19,859,127	$ 670,012	14,618,602	20,553,168
Cost [member]
Disclosure of associates and joint ventures [line items]
Goodwill	12,348,607		12,479,305	$ 12,495,515	416,620	$ 421,029	$ 12,434,411
Carrying amount	48,567,386		49,454,289		1,638,576
Siliconware Precision Industries Co., Ltd. [member]
Disclosure of associates and joint ventures [line items]
Current assets	49,065,912		50,451,295		1,655,395
Non-current assets	101,693,417		107,573,251		3,430,952
Current liabilities	(26,194,615)		(41,088,439)		(883,759)
Non-current liabilities	(27,213,266)		(17,518,410)		(918,126)
Equity	$ 97,351,448		$ 99,417,697		3,284,462
Proportion of the Group's ownership interest in SPIL	33.29%	33.29%	33.29%
Net assets attributable to the Group	$ 32,408,297		$ 33,096,151		1,093,397
Goodwill	12,802,074		12,802,074		431,919
Operating revenue	83,554,385	$ 2,818,974	85,111,913
Gross profit	12,464,792	420,540	15,027,247
Profit before income tax	4,347,810	146,687	7,351,661
Net profit for the year	2,822,231	95,217	5,484,462
Other comprehensive income (loss) for the year	579,057	19,536	(2,373,532)
Total comprehensive income for the year	3,401,288	114,753	3,110,930
Cash dividends received from SPIL	1,815,275	$ 61,244	3,941,740
Siliconware Precision Industries Co., Ltd. [member] | Cost [member]
Disclosure of associates and joint ventures [line items]
Carrying amount	$ 45,210,371		$ 45,898,225		$ 1,525,316

Investments Accounted for Us103

Investments Accounted for Using the Equity Method - Summary of Aggregate Information of Associates that are Not Individually Material (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of associates and joint ventures [line items]
Net profit (loss) for the year	$ 24,497,060	$ 826,487	$ 22,577,861	$ 20,700,715
Other comprehensive income (loss) for the year	(4,637,933)	(156,475)	(7,959,259)	(147,547)
Total comprehensive income (loss) for the year	19,859,127	670,012	14,618,602	20,553,168
Associates that are not individually material [member]
Disclosure of associates and joint ventures [line items]
Net profit (loss) for the year	(190,532)	(6,428)	(139,366)	120,749
Other comprehensive income (loss) for the year	59,676	2,013	(115,650)	(2,916)
Total comprehensive income (loss) for the year	$ (130,856)	$ (4,415)	$ (255,016)	$ 117,833

Investments Accounted for Us104

Investments Accounted for Using the Equity Method - Summary of Aggregate Information of the Joint Venture that is Not Individually Material (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Joint venture that is not individually material [member]
Disclosure of joint ventures [line items]
The Group's share of net loss and total comprehensive loss for the year	$ (184,366)	$ (6,220)	$ (90,478)

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	$ 143,880,241
Depreciation expense	28,747,518	$ 969,890	$ 28,961,614	$ 28,938,770
Additions	23,677,682	798,842	27,680,862	28,280,821
Ending balance	135,168,406	4,560,338	143,880,241
Cost [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	364,012,147	12,281,112	355,233,007	336,787,690
Additions	23,677,682	798,842	27,680,862	28,280,821
Disposals	(9,896,428)	(333,887)	(7,069,481)	(8,700,239)
Reclassification	(474,352)	(16,003)	(175)	130,809
Acquisitions through business combinations			1,159
Effect of foreign currency exchange differences	(6,998,807)	(236,128)	(11,833,225)	(1,266,074)
Ending balance	370,320,242	12,493,936	364,012,147	355,233,007
Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	220,131,906	7,426,852	205,235,932	185,200,575
Depreciation expense	28,625,287	965,766	28,961,614	28,938,770
Impairment losses recognized	289,558	9,769	888,231	258,129
Disposals	(8,757,164)	(295,450)	(6,245,611)	(8,372,341)
Reclassification	(199,745)	(6,740)		(3,208)
Acquisitions through business combinations			824
Effect of foreign currency exchange differences	(4,938,006)	(166,599)	(8,709,084)	(785,993)
Ending balance	235,151,836	7,933,598	220,131,906	205,235,932
Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	3,365,013
Ending balance	3,258,518	109,937	3,365,013
Land [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	3,365,013	113,529	3,381,300	3,348,018
Reclassification	(35,965)	(1,212)
Effect of foreign currency exchange differences	(70,530)	(2,380)	(16,287)	33,282
Ending balance	3,258,518	109,937	3,365,013	3,381,300
Buildings and improvements [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	58,028,631
Ending balance	58,272,864	1,966,021	58,028,631
Buildings and improvements [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	96,258,175	3,247,577	94,447,932	86,725,254
Additions	350,434	11,823	22,341	132,584
Disposals	(609,294)	(20,556)	(684,698)	(405,040)
Reclassification	6,483,392	218,738	5,110,102	8,579,472
Effect of foreign currency exchange differences	(2,294,779)	(77,422)	(2,637,502)	(584,338)
Ending balance	100,187,928	3,380,160	96,258,175	94,447,932
Buildings and improvements [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	38,229,544	1,289,796	34,646,878	30,329,544
Depreciation expense	5,156,558	173,973	5,114,263	4,790,646
Impairment losses recognized	2,310	78	620	120,424
Disposals	(478,903)	(16,157)	(449,198)	(308,895)
Reclassification	(210,080)	(7,088)	(5,123)	5,704
Effect of foreign currency exchange differences	(784,365)	(26,463)	(1,077,896)	(290,545)
Ending balance	41,915,064	1,414,139	38,229,544	34,646,878
Machinery and equipment1 [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	72,700,762
Ending balance	66,185,198	2,232,969	72,700,762
Machinery and equipment1 [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	248,200,756	8,373,845	243,283,607	233,669,627
Additions	102,301	3,451	94,480	553,496
Disposals	(8,449,949)	(285,086)	(5,956,179)	(8,041,933)
Reclassification	18,331,738	618,480	19,661,732	18,054,712
Effect of foreign currency exchange differences	(4,986,843)	(168,247)	(8,882,884)	(952,295)
Ending balance	253,198,003	8,542,443	248,200,756	243,283,607
Machinery and equipment1 [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	175,499,994	5,921,052	164,568,298	149,497,980
Depreciation expense	22,722,307	766,610	22,983,290	23,372,408
Impairment losses recognized	286,880	9,679	876,123	31,116
Disposals	(7,540,654)	(254,408)	(5,544,489)	(7,838,937)
Reclassification	34,452	1,162	9,660	(11,920)
Effect of foreign currency exchange differences	(3,990,174)	(134,621)	(7,392,888)	(482,349)
Ending balance	187,012,805	6,309,474	175,499,994	164,568,298
Other equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	2,089,581
Ending balance	1,588,113	53,580	2,089,581
Other equipment [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	8,474,661	285,920	7,722,408	7,182,574
Additions	130,659	4,408	470,901	401,417
Disposals	(763,937)	(25,774)	(159,822)	(232,555)
Reclassification	174,947	5,902	691,276	389,783
Acquisitions through business combinations			1,159
Effect of foreign currency exchange differences	(204,250)	(6,891)	(251,261)	(18,811)
Ending balance	7,812,080	263,565	8,474,661	7,722,408
Other equipment [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	6,385,080	215,421	5,907,414	5,365,887
Depreciation expense	746,422	25,183	864,061	775,716
Impairment losses recognized	368	12	5,564
Disposals	(720,319)	(24,302)	(151,875)	(224,509)
Reclassification	(24,117)	(814)	(4,537)	3,008
Acquisitions through business combinations			824
Effect of foreign currency exchange differences	(163,467)	(5,515)	(236,371)	(12,688)
Ending balance	6,223,967	209,985	6,385,080	5,907,414
Construction in progress and machinery in transit [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	7,696,254
Ending balance	5,863,713	197,831	7,696,254
Construction in progress and machinery in transit [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	7,713,542	260,241	6,397,760	5,862,217
Additions	23,094,288	779,160	27,093,140	27,193,324
Disposals	(73,248)	(2,471)	(268,782)	(20,711)
Reclassification	(25,428,464)	(857,911)	(25,463,285)	(26,893,158)
Effect of foreign currency exchange differences	557,595	18,812	(45,291)	256,088
Ending balance	5,863,713	197,831	7,713,542	6,397,760
Construction in progress and machinery in transit [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning balance	17,288	583	113,342	7,164
Impairment losses recognized			5,924	106,589
Disposals	$ (17,288)	$ (583)	(100,049)
Effect of foreign currency exchange differences			(1,929)	(411)
Ending balance			$ 17,288	$ 113,342

Property, Plant and Equipmen106

Property, Plant and Equipment - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Impairment losses recognized property plant an equipment	$ 289,558	$ 9,769	$ 888,231	$ 258,129

Property, Plant and Equipmen107

Property, Plant and Equipment - Summary of Property, Plant and Equipment Depreciated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2017
Main plant buildings [Member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	10 years
Main plant buildings [Member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	40 years
Cleanrooms [Member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	10 years
Cleanrooms [Member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	20 years
Others [Member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	3 years
Others [Member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	20 years
Machinery and equipment1 [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	2 years
Machinery and equipment1 [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	10 years
Other equipment [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	2 years
Other equipment [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Property, plant and equipment useful lives	20 years

Investment Properties - Summary

Investment Properties - Summary of Investment Properties (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of detailed information about investment property [line items]
Depreciation expenses	$ 122,231	$ 4,124
Balance at December 31, 2017	8,119,436	273,935
Cost [member]
Disclosure of detailed information about investment property [line items]
Additions	186,535	6,293
Disposals	(342)	(11)
Transfers from inventories related to real estate business and property, plant and equipment	8,150,075	274,968
Effects of foreign currency exchange differences	106,482	3,593
Balance at December 31, 2017	8,442,750	284,843
Cost [member] | Land [member]
Disclosure of detailed information about investment property [line items]
Transfers from inventories related to real estate business and property, plant and equipment	35,965	1,213
Balance at December 31, 2017	35,965	1,213
Cost [member] | Buildings and improvements [member]
Disclosure of detailed information about investment property [line items]
Additions	186,535	6,293
Disposals	(342)	(11)
Transfers from inventories related to real estate business and property, plant and equipment	8,114,110	273,755
Effects of foreign currency exchange differences	106,482	3,593
Balance at December 31, 2017	8,406,785	283,630
Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about investment property [line items]
Depreciation expenses	122,231	4,124
Disposals	(161)	(5)
Transfers from inventories related to real estate business and property, plant and equipment	199,745	6,739
Effects of foreign currency exchange differences	1,499	50
Balance at December 31, 2017	323,314	10,908
Accumulated depreciation, amortisation and impairment [member] | Buildings and improvements [member]
Disclosure of detailed information about investment property [line items]
Depreciation expenses	122,231	4,124
Disposals	(161)	(5)
Transfers from inventories related to real estate business and property, plant and equipment	199,745	6,739
Effects of foreign currency exchange differences	1,499	50
Balance at December 31, 2017	$ 323,314	$ 10,908

Investment Properties - Investm

Investment Properties - Investment Properties Depreciated Using Straight-Line Method Over Their Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2017
Bottom of range [member] | Main plant buildings [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	10 years
Bottom of range [member] | Other Investment Properties [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	3 years
Top of range [member] | Main plant buildings [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	40 years
Top of range [member] | Other Investment Properties [Member]
Disclosure of detailed information about investment property [line items]
Investment properties are depreciated using the straight-line method over their estimated useful lives	20 years

Investment Properties - Additio

Investment Properties - Additional Information (Detail) - Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of detailed information about investment property [line items]
Fair value of investment properties	$ 8,119,436	$ 273,935
Level 3 of fair value hierarchy [member] | Fair value [member]
Disclosure of detailed information about investment property [line items]
Fair value of investment properties	$ 11,560,440	$ 390,028

Goodwill - Summary of Goodwill

Goodwill - Summary of Goodwill (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of reconciliation of changes in goodwill [line items]
Beginning balance	$ 10,490,309	$ 353,924	$ 10,506,519	$ 10,445,415
Acquisitions through business combinations (retrospectively adjusted)			15,323
Impairment losses recognized	(425,117)	(14,343)
Effect of foreign currency exchange differences	(130,698)	(4,409)	(31,533)	61,104
Ending balance	9,934,494	335,172	10,490,309	10,506,519
Cost [member]
Disclosure of reconciliation of changes in goodwill [line items]
Beginning balance	12,479,305	421,029	12,495,515	12,434,411
Acquisitions through business combinations (retrospectively adjusted)			15,323
Effect of foreign currency exchange differences	(130,698)	(4,409)	(31,533)	61,104
Ending balance	12,348,607	416,620	12,479,305	12,495,515
Accumulated impairment [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Beginning balance	1,988,996	67,105	1,988,996	1,988,996
Impairment losses recognized	425,117	14,343
Ending balance	$ 2,414,113	$ 81,448	$ 1,988,996	$ 1,988,996

Goodwill - Summary of Carrying

Goodwill - Summary of Carrying Amount of Goodwill Allocated to Cash-generating Units (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Disclosure of information for cash-generating units [line items]
Goodwill	$ 9,934,494	$ 335,172	$ 10,490,309	$ 353,924	$ 10,506,519	$ 10,445,415
Testing segment [member]
Disclosure of information for cash-generating units [line items]
Goodwill	7,775,581	262,334	7,868,961
All other segments [member]
Disclosure of information for cash-generating units [line items]
Goodwill	$ 2,158,913	$ 72,838	$ 2,621,348

Goodwill - Additional Informati

Goodwill - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016	Dec. 31, 2015
Disclosure of reconciliation of changes in goodwill [line items]
Percentage of cash flows growth rate beyond five-year period	2.00%	2.00%	2.00%	2.00%
Impairment loss on goodwill	$ 425,117	$ 14,343
Bottom of range [member]
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	8.97%	8.97%	9.09%	8.67%
Top of range [member]
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	11.29%	11.29%	10.49%	10.71%

Other Intangible Assets - Summa

Other Intangible Assets - Summary of Carrying Amounts of Each Class of Other Intangible Assets (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about intangible assets [line items]
Beginning balance	$ 1,617,261
Additions	277,825	$ 9,373	$ 675,144	$ 491,135
Amortization expense	457,666	15,441	508,823	579,894
Ending balance	1,406,865	47,465	1,617,261
Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	5,174,700	174,585	4,601,416	6,785,494
Additions	277,825	9,373	675,144	491,135
Disposals	(212,317)	(7,163)	(122,946)	(2,655,923)
Reclassification			786	12,360
Acquisitions through business combinations			105,509
Effect of foreign currency exchange differences	(49,880)	(1,684)	(85,209)	(31,650)
Ending balance	5,190,328	175,111	5,174,700	4,601,416
Accumulated depreciation and amortization [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	3,557,439	120,020	3,219,323	5,317,623
Amortization expense	457,666	15,441	508,823	579,894
Disposals	(196,224)	(6,620)	(101,174)	(2,654,695)
Reclassification			786	3,190
Acquisitions through business combinations			506
Effect of foreign currency exchange differences	(35,418)	(1,195)	(70,825)	(26,689)
Ending balance	3,783,463	127,646	3,557,439	3,219,323
Customer relationships [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	194,089
Ending balance	113,776	3,839	194,089
Customer relationships [Member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	915,636	30,892	915,636	1,579,015
Disposals			(41,099)	(663,379)
Acquisitions through business combinations			41,099
Ending balance	915,636	30,892	915,636	915,636
Customer relationships [Member] | Accumulated depreciation and amortization [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	721,547	24,343	641,234	1,077,514
Amortization expense	80,313	2,710	121,412	227,099
Disposals			(41,099)	(663,379)
Ending balance	801,860	27,053	721,547	641,234
Computer software [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	943,527
Ending balance	864,331	29,161	943,527
Computer software [Member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	3,552,229	119,846	3,338,360	2,882,932
Additions	265,497	8,957	372,188	481,412
Disposals	(83,595)	(2,820)	(80,537)	(8,426)
Reclassification				12,360
Effect of foreign currency exchange differences	(47,679)	(1,609)	(77,782)	(29,918)
Ending balance	3,686,452	124,374	3,552,229	3,338,360
Computer software [Member] | Accumulated depreciation and amortization [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	2,608,702	88,012	2,385,038	2,084,805
Amortization expense	316,580	10,681	345,836	325,856
Disposals	(72,481)	(2,445)	(58,765)	(7,402)
Reclassification				3,190
Effect of foreign currency exchange differences	(30,680)	(1,035)	(63,407)	(21,411)
Ending balance	2,822,121	95,213	2,608,702	2,385,038
Patents and acquired specific technology [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	359,227
Ending balance	319,402	10,776	359,227
Patents and acquired specific technology [Member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	514,443	17,356	154,082	2,139,138
Additions			301,351	209
Disposals	(123,744)	(4,175)	(1,310)	(1,983,914)
Reclassification			786
Acquisitions through business combinations			64,380
Effect of foreign currency exchange differences	(1,213)	(41)	(4,846)	(1,351)
Ending balance	389,486	13,140	514,443	154,082
Patents and acquired specific technology [Member] | Accumulated depreciation and amortization [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	155,216	5,237	138,386	2,118,254
Amortization expense	43,493	1,467	24,154	9,461
Disposals	(123,743)	(4,175)	(1,310)	(1,983,914)
Reclassification			786
Acquisitions through business combinations			483
Effect of foreign currency exchange differences	(4,882)	(165)	(7,283)	(5,415)
Ending balance	70,084	2,364	155,216	138,386
Others [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	120,418
Ending balance	109,356	3,689	120,418
Others [Member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	192,392	6,491	193,338	184,409
Additions	12,328	416	1,605	9,514
Disposals	(4,978)	(168)		(204)
Acquisitions through business combinations			30
Effect of foreign currency exchange differences	(988)	(34)	(2,581)	(381)
Ending balance	198,754	6,705	192,392	193,338
Others [Member] | Accumulated depreciation and amortization [Member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	71,974	2,428	54,665	37,050
Amortization expense	17,280	583	17,421	17,478
Acquisitions through business combinations			23
Effect of foreign currency exchange differences	144	5	(135)	137
Ending balance	$ 89,398	$ 3,016	$ 71,974	$ 54,665

Other Intangible Assets - Su115

Other Intangible Assets - Summary of Other Intangible Assets Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2017
Customer relationships [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	11 years
Bottom of range [member] | Computer software [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	2 years
Bottom of range [member] | Patents and acquired specific technology [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	5 years
Bottom of range [member] | Others [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	5 years
Top of range [member] | Computer software [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	10 years
Top of range [member] | Patents and acquired specific technology [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	15 years
Top of range [member] | Others [Member]
Disclosure of intangible assets with indefinite useful life [line items]
Other intangible assets useful lives	32 years

Long-term Prepayments for Le116

Long-term Prepayments for Lease - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure of finance lease and operating lease by lessee [line items]
Long-term lease expire date	From 2049 to 2074
Bottom of range [member]
Disclosure of finance lease and operating lease by lessee [line items]
Long-term lease period	40 years
Top of range [member]
Disclosure of finance lease and operating lease by lessee [line items]
Long-term lease period	70 years

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Unsecured revolving bank loans [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	0.80%	0.80%	0.70%
Unsecured revolving bank loans [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	4.79%	4.79%	8.99%
Longterm bank loans with fixed interest rates [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	1.20%	1.20%	1.20%
Long term bank loans with fixed interest rates	$ 1,500,000	$ 50,607	$ 1,500,000

Borrowings - Summary of Bank Lo

Borrowings - Summary of Bank Loans (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Less: current portion	$ 8,261,625	$ 278,732	$ 6,567,565
Noncurrent portion	27,145,003	915,823	46,547,998
Bank loans [member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	31,907,496	1,076,501	49,616,222
Less: current portion	6,761,625	228,125	6,567,565
Noncurrent portion	25,145,871	848,376	43,048,657
Bank loans [member] | Cost [member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	31,908,696	1,076,541	49,623,420
Bank loans [member] | Cost [member] | Syndicated bank loans [Member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	4,761,600	160,647	9,223,500
Bank loans [member] | Cost [member] | Other loans [Member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	22,441,947	757,151	36,009,917
Bank loans [member] | Cost [member] | Mortgage loans [Member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	4,705,149	158,743	4,390,003
Bank loans [member] | Net Unamortized Debt Issue Costs [member]
Disclosure of detailed information about borrowings [line items]
Long-term borrowings	$ 1,200	$ 40	$ 7,198

Borrowings - Summary of Bank119

Borrowings - Summary of Bank Loans (Parenthetical) (Detail) - Bank loans [member]	Dec. 31, 2017	Dec. 31, 2016
Syndicated bank loans [Member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates		2.55%
Syndicated bank loans [Member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	2.61%
Syndicated bank loans [Member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	2.70%
Other loans [Member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	0.93%	0.74%
Other loans [Member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	2.10%	4.48%
Mortgage loans [Member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	4.95%	4.95%
Mortgage loans [Member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	5.39%	5.39%

Borrowings - Summary of Long-te

Borrowings - Summary of Long-term Bills Payable (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Long-term bills payable	$ 1,999,132	$ 67,447	$ 1,999,341
Unamortized Discounts [member]
Disclosure of detailed information about borrowings [line items]
Long-term bills payable	868	29	659
Longterm Bills Payable [member]
Disclosure of detailed information about borrowings [line items]
Long-term bills payable	2,000,000	67,476	2,000,000
China Bills Finance Corporation [member]
Disclosure of detailed information about borrowings [line items]
Long-term bills payable	1,000,000	33,738
International Bills Finance Corporation [member]
Disclosure of detailed information about borrowings [line items]
Long-term bills payable	$ 1,000,000	$ 33,738
Ta Ching Bills Finance Corporation [member]
Disclosure of detailed information about borrowings [line items]
Long-term bills payable			$ 2,000,000

Borrowings - Summary of Long121

Borrowings - Summary of Long-term Bills Payable (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
China Bills Finance Corporation [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	0.96%
Borrowings maturity	February 2,019
International Bills Finance Corporation [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates	0.96%
Borrowings maturity	March 2,019
Ta Ching Bills Finance Corporation [member]
Disclosure of detailed information about borrowings [line items]
Annual interest rates		1.00%
Borrowings maturity		December 2,017

Bonds Payable - Summary of Bond

Bonds Payable - Summary of Bonds Payable (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Bonds payable	$ 23,142,780	$ 780,796	$ 36,999,903
Less: current portion	6,161,197	207,868	9,658,346
Noncurrent portion	16,981,583	572,928	27,341,557
Cost [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	23,185,600	782,240	37,760,600
Cost [member] | Repayable at maturity in January 2021 [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	7,000,000	236,168	7,000,000
Cost [member] | Repayable at maturity in January 2023 [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	2,000,000	67,476	2,000,000
Cost [member] | Repayable at maturity in January 2022 [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	3,700,000	124,831
Cost [member] | Repayable at maturity in January 2024 [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	4,300,000	145,074
Cost [member] | US$400,000 thousand [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable			12,900,000
Cost [member] | US$200,000 thousand [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	6,185,600	208,691	6,185,600
Cost [member] | Secured Overseas Bonds One [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable			9,675,000
Discounts on bonds payable [member]
Disclosure of detailed information about borrowings [line items]
Bonds payable	$ 42,820	$ 1,444	$ 760,697

Bonds Payable - Summary of B123

Bonds Payable - Summary of Bonds Payable (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Repayable at maturity in January 2021 [member]
Disclosure of detailed information about borrowings [line items]
Interest rate	1.30%	1.30%
Repayable at maturity in January 2023 [member]
Disclosure of detailed information about borrowings [line items]
Interest rate	1.50%	1.50%
Repayable at maturity in January 2022 [member]
Disclosure of detailed information about borrowings [line items]
Interest rate	1.25%
Repayable at maturity in January 2024 [member]
Disclosure of detailed information about borrowings [line items]
Interest rate	1.45%
US$400,000 thousand [member] | Cost [member]
Disclosure of detailed information about borrowings [line items]
Notional Amount	$ 400,000,000
US$200,000 thousand [member]
Disclosure of detailed information about borrowings [line items]
Notional Amount			$ 200,000,000
US$200,000 thousand [member] | Cost [member]
Disclosure of detailed information about borrowings [line items]
Notional Amount	200,000,000
Secured Overseas Bonds One [member]
Disclosure of detailed information about borrowings [line items]
Interest rate		2.125%		2.125%
Notional Amount				$ 300,000,000
Secured Overseas Bonds One [member] | Cost [member]
Disclosure of detailed information about borrowings [line items]
Notional Amount	$ 300,000,000
Bonds repayment date	July 2,017

Bonds Payable - Additional Info

Bonds Payable - Additional Information (Detail) $ / shares in Units, $ / shares in Units, $ in Thousands, $ in Thousands	1 Months Ended				3 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)	Jul. 31, 2015TWD ($)$ / shares	Jul. 31, 2014TWD ($)	Sep. 30, 2013USD ($)$ / shares	Sep. 30, 2017$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016$ / shares	Jul. 31, 2015USD ($)$ / shares	Jul. 31, 2014USD ($)	Sep. 30, 2013$ / shares
Unsecured overseas convertible bonds [Member]
Disclosure of detailed information about borrowings [line items]
Bonds face amount				$ 400,000		$ 400,000	$ 400,000
Bonds maturity period				5 years
Bonds denomination amount				$ 200
Unsecured overseas bonds conversion price | $ / shares				$ 33.085				$ 28.99
Unsecured overseas bonds fixed exchange rate | $ / shares											$ 29.956
Unsecured overseas convertible bonds [Member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Unsecured overseas bonds conversion price | (per share)					$ 27.95	$ 0.94
Unsecured overseas convertible bonds [Member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Unsecured overseas bonds conversion price | (per share)					28.96	$ 0.98
US$400,000 thousand [member]
Disclosure of detailed information about borrowings [line items]
Unsecured overseas bonds fixed exchange rate | $ / shares					$ 29.956
Common shares trading period					20 days	20 days	20 days
Effective interest rate of debt host contract			3.16%
Aggregate fair value of bonds options			$ 1,667,950
Early redemption of outstanding bonds	$ 400
US$400,000 thousand [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Conversion price percentage				130.00%
Aggregate principal amount of bonds redeemed				90.00%
US$200,000 thousand [member]
Disclosure of detailed information about borrowings [line items]
Bonds face amount									$ 200,000
Bonds maturity period		2 years 9 months
Bonds denomination amount									$ 200
Unsecured overseas bonds conversion price | (per share)		$ 54.55				$ 1.61	$ 47.76	$ 49.52
Unsecured overseas bonds fixed exchange rate | $ / shares									$ 30.928
Common shares trading period						20 days	20 days
Effective interest rate of debt host contract		1.58%
Aggregate fair value of bonds options		$ 214,022
US$200,000 thousand [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Conversion price percentage		130.00%
Aggregate principal amount of bonds redeemed		90.00%
US$200,000 thousand [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Common shares trading period						30 days	30 days
Secured Overseas Bonds One [member]
Disclosure of detailed information about borrowings [line items]
Bonds face amount										$ 300,000
Bonds maturity period			3 years
Percentage of ownership interest in subsidiary			100.00%
Annual interest rates of bonds			2.125%					2.125%		2.125%

Other Payables - Summary of Oth

Other Payables - Summary of Other Payables (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Subclassifications of assets, liabilities and equities [abstract]
Accrued salary and bonus	$ 7,292,254	$ 246,027	$ 6,606,406
Payables for property, plant and equipment	4,623,268	155,981	5,605,528
Accrued employees' compensation and remuneration to directors	2,568,880	86,669	2,400,778
Accrued employee insurance	657,176	22,172	617,419
Accrued utilities	417,257	14,077	410,796
Payables for patents and acquired specific technology (Note 35)	93,000	3,138	120,938
Others	5,726,052	193,187	5,760,169
Other payables	$ 21,377,887	$ 721,251	$ 21,522,034

Retirement Benefit Plans - Addi

Retirement Benefit Plans - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)yr	Dec. 31, 2017USD ($)yr	Dec. 31, 2016TWD ($)yr	Dec. 31, 2015TWD ($)	Dec. 31, 2017USD ($)
Disclosure of defined benefit plans [line items]
Percentage of monthly pension contributions	6.00%	6.00%
Pension costs	$ 266,267	$ 8,983	$ 394,741	$ 413,490
Expected contribution to defined benefit plans	$ 521,324	$ 9,208	$ 272,911
Bottom of range [member]
Disclosure of defined benefit plans [line items]
Average duration of the defined benefit obligation	8	8	8
Top of range [member]
Disclosure of defined benefit plans [line items]
Average duration of the defined benefit obligation	14	14	15
Pension plans for executive managers [member]
Disclosure of defined benefit plans [line items]
Pension costs	$ 3,171	$ 107	$ 6,872	2,302
Pension payments	0	$ 0	0	$ 2,549
Accrued pension liabilities	$ 209,637		$ 206,467		$ 7,073

Retirement Benefit Plans - Summ

Retirement Benefit Plans - Summary of Defined Benefit Plans Amounts Included in Consolidated Balance Sheets (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Disclosure of net defined benefit liability (asset) [abstract]
Present value of the defined benefit obligation	$ 7,910,638	$ 266,891	$ 8,389,884
Fair value of plan assets	(4,341,373)	(146,470)	(4,417,367)
Present value of unfunded defined benefit obligation	3,569,265	120,421	3,972,517	$ 134,026	$ 3,999,947	$ 4,171,806
Recorded under other payables	(24,638)	(831)	(22,273)
Recorded under other current assets	182,421	6,154	15,542
Net defined benefit liability	$ 3,727,048	$ 125,744	$ 3,965,786

Retirement Benefit Plans - S128

Retirement Benefit Plans - Summary of Movements in Net Defined Benefit Liability (Asset) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of net defined benefit liability (asset) [line items]
Beginning balance	$ 3,972,517	$ 134,026	$ 3,999,947	$ 4,171,806
Current service cost	278,412	9,393	329,838	335,655
Past service cost and gain on settlements	(68,979)	(2,328)
Net interest expense (income)	53,663	1,811	58,031	75,533
Recognized in profit or loss	263,096	8,876	387,869	411,188
Return on plan assets (excluding amounts included in net interest)	52,124	1,759	54,549	12,426
Actuarial loss arising from changes in financial assumptions	56,860	1,918	156,193	309,695
Actuarial loss (gain) arising from experience adjustments	(315,090)	(10,631)	200,723	(243,363)
Actuarial loss (gain) arising from changes in demographic assumptions	762	26	5,716	(15,847)
Recognized in other comprehensive income	(205,344)	(6,928)	417,181	62,911
Contributions from the employer	(484,790)	(16,356)	(807,232)	(611,581)
Benefits paid from the Group	(96,575)	(3,258)	(36,033)	(43,088)
Exchange differences on foreign plans	120,361	4,061	10,785	8,711
Ending balance	3,569,265	120,421	3,972,517	3,999,947
Defined benefit obligation [member]
Disclosure of net defined benefit liability (asset) [line items]
Beginning balance	8,389,884	283,060	7,973,676	7,674,293
Current service cost	278,412	9,393	329,838	335,655
Past service cost and gain on settlements	(68,979)	(2,328)
Net interest expense (income)	157,404	5,311	167,111	183,889
Recognized in profit or loss	366,837	12,376	496,949	519,544
Actuarial loss arising from changes in financial assumptions	56,860	1,918	156,193	309,695
Actuarial loss (gain) arising from experience adjustments	(315,090)	(10,631)	200,723	(243,363)
Actuarial loss (gain) arising from changes in demographic assumptions	762	26	5,716	(15,847)
Recognized in other comprehensive income	(257,468)	(8,687)	362,632	50,485
Benefits paid from the pension fund	(690,830)	(23,307)	(308,471)	(192,928)
Benefits paid from the Group	(96,575)	(3,258)	(36,033)	(43,088)
Liabilities assumed in a business combination			535
Exchange differences on foreign plans	198,790	6,707	(99,404)	(34,630)
Ending balance	7,910,638	266,891	8,389,884	7,973,676
Fair value of plan assets [member]
Disclosure of net defined benefit liability (asset) [line items]
Beginning balance	(4,417,367)	(149,034)	(3,973,729)	(3,502,487)
Net interest expense (income)	(103,741)	(3,500)	(109,080)	(108,356)
Recognized in profit or loss	(103,741)	(3,500)	(109,080)	(108,356)
Return on plan assets (excluding amounts included in net interest)	52,124	1,759	54,549	12,426
Recognized in other comprehensive income	52,124	1,759	54,549	12,426
Contributions from the employer	(484,790)	(16,356)	(807,232)	(611,581)
Benefits paid from the pension fund	690,830	23,307	308,471	192,928
Liabilities assumed in a business combination			(535)
Exchange differences on foreign plans	(78,429)	(2,646)	110,189	43,341
Ending balance	$ (4,341,373)	$ (146,470)	$ (4,417,367)	$ (3,973,729)

Retirement Benefit Plans - S129

Retirement Benefit Plans - Summary of Fair Value of the Plan Assets by Major Categories (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of fair value of plan assets [abstract]
Cash	$ 2,317,764	$ 78,197	$ 2,232,367
Debt instruments	691,619	23,334	1,030,384
Equity instruments	1,254,109	42,311	1,071,777
Others	77,881	2,628	82,839
Total	$ 4,341,373	$ 146,470	$ 4,417,367

Retirement Benefit Plans - S130

Retirement Benefit Plans - Summary of Key Assumptions Used for the Actuarial Valuations (Detail)	Dec. 31, 2017	Dec. 31, 2016
Bottom of range [member]
Disclosure of defined benefit plans [line items]
Discount rates	0.06%	0.06%
Expected rates of salary increase	2.00%	2.00%
Top of range [member]
Disclosure of defined benefit plans [line items]
Discount rates	3.85%	3.58%
Expected rates of salary increase	4.42%	4.42%

Retirement Benefit Plans - S131

Retirement Benefit Plans - Summary of Sensitivity Analysis on Defined Obligations (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Actuarial assumption of discount rates [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in defined obligation due to increase in actuarial assumption	$ (455,158)	$ (15,356)	$ (464,647)
Change in defined obligation due to decrease in actuarial assumption	461,891	15,583	508,862
Actuarial assumption of expected rates of salary increases [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Change in defined obligation due to increase in actuarial assumption	453,792	15,310	500,051
Change in defined obligation due to decrease in actuarial assumption	$ (444,493)	$ (14,996)	$ (452,956)

Retirement Benefit Plans - S132

Retirement Benefit Plans - Summary of Sensitivity Analysis on Defined Obligations (Parenthetical) (Detail)	Dec. 31, 2017	Dec. 31, 2016
Actuarial assumption of discount rates [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Percentage increase in actuarial assumption	0.50%	0.50%
Percentage decrease in actuarial assumption	0.50%	0.50%
Actuarial assumption of expected rates of salary increases [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Percentage increase in actuarial assumption	0.50%	0.50%
Percentage decrease in actuarial assumption	0.50%	0.50%

Retirement Benefit Plans - S133

Retirement Benefit Plans - Summary of Maturity Analysis of Undiscounted Pension Benefit (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of defined benefit plans [line items]
Maturity analysis of undiscounted pension benefit	$ 18,350,395	$ 619,109	$ 19,095,234
Less than 1 year [member]
Disclosure of defined benefit plans [line items]
Maturity analysis of undiscounted pension benefit	291,152	9,823	292,100
1-5 years [member]
Disclosure of defined benefit plans [line items]
Maturity analysis of undiscounted pension benefit	1,551,496	52,345	1,673,549
More than 5 years [member]
Disclosure of defined benefit plans [line items]
Maturity analysis of undiscounted pension benefit	$ 16,507,747	$ 556,941	$ 17,129,585

Equity - Summary of Share Capit

Equity - Summary of Share Capital (Detail) shares in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016TWD ($)shares
Disclosure of classes of share capital [abstract]
Numbers of shares authorized (in thousands)	10,000,000	10,000,000	10,000,000
Numbers of shares reserved (in thousands) Employee share options	800,000	800,000	800,000
Number of shares issued and fully paid (in thousands)	8,738,079	8,738,079	7,946,184
Share capital authorized	$ 100,000,000	$ 3,373,819	$ 100,000,000
Share capital reserved Employee share options	8,000,000	269,906	8,000,000
Share capital issued	$ 87,380,787	$ 2,948,070	$ 79,568,040

Equity - Additional Information

Equity - Additional Information (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / shares$ / sharesshares	Oct. 13, 2017shares	Jul. 13, 2017shares	Dec. 31, 2016shares
Disclosure of classes of share capital [line items]
Par value of ordinary shares issued | $ / shares	$ 10
Shares included in authorized shares not yet completed share registration process	500,000			500,000
Number of ordinary shares issued		323,094	101,164
Percentage of legal reserve	10.00%
Percentage of legal reserve on share capital	25.00%
Percentage of ordinary shares repurchased	1.53%
Average repurchase price per share | $ / shares	$ 44.45
Converted bonds [member]
Disclosure of classes of share capital [line items]
Ordinary shares issued under conversion of Bonds	424,258
Top of range [member]
Disclosure of classes of share capital [line items]
Percentage of cash dividend on dividend distribution	30.00%
Number of ordinary shares approved for repurchase	120,000
American depository shares (ADs) [member]
Disclosure of classes of share capital [line items]
Number of shares represented by each ADS	5
Number of shares outstanding	115,261			125,518
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Number of shares outstanding	576,305			627,590
Cash capital increase [member]
Disclosure of classes of share capital [line items]
Number of ordinary shares issued	300,000
Share price | $ / shares	$ 34.3

Equity - Summary of Capital Sur

Equity - Summary of Capital Surplus (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of classes of share capital [abstract]
Arising from issuance of ordinary shares	$ 21,553,853	$ 727,188	$ 5,844,397
Arising from conversion of bond payable	1,930,066	65,117
Arising from the difference between consideration received and the carrying amount of the subsidiaries' net assets during actual disposal or acquisition	7,176,958	242,137	7,176,958
Arising from changes in percentage of ownership interest in subsidiaries	6,084,895	205,293	6,134,228
Arising from treasury share transactions	1,151,345	38,844	950,368
Arising from exercised employee share options	1,089,178	36,747	630,411
Arising from expired employee share options	223,454	7,539	3,626
Arising from share of changes in capital surplus of associates	83,733	2,825	82,243
Arising from employee share options	960,888	32,419	1,230,247
Arising from equity component of convertible bonds	214,022	7,221	214,022
Others	155,936	5,261
Capital surplus	$ 40,624,328	$ 1,370,591	$ 22,266,500

Equity - Summary of Appropriati

Equity - Summary of Appropriations of Earnings (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of classes of share capital [line items]
Cash dividends	$ (11,415,198)	$ (12,476,779)	$ (15,589,825)
Appropriations of earnings	(11,415,198)	$ (12,476,779)	$ (15,589,825)
Cash dividends		$ 1.40	$ 1.60
Unappropriated earnings [member]
Disclosure of classes of share capital [line items]
Legal reserve	(2,168,034)	$ (1,947,887)	$ (2,359,267)
Cash dividends	(11,415,198)	(12,476,779)	(15,589,825)
Appropriations of earnings	$ (13,583,232)	$ (14,424,666)	$ (17,949,092)

Equity - Summary of Exchange Di

Equity - Summary of Exchange Differences on Translating Foreign Operations (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Beginning balance	$ 166,841,165		$ 165,924,980	$ 155,691,394
Exchange differences arising on translating foreign operations	(5,287,734)	$ (178,399)	(6,445,643)	(63,509)
Share of exchange difference of associates and joint venture accounted for using the equity method	264,389	8,920	(871,679)	(4,832)
Ending balance	201,310,187	6,791,842	166,841,165	165,924,980
Exchange differences on translating foreign operations [member]
Beginning balance	(1,643,623)	(55,453)	4,492,671	4,540,862
Exchange differences arising on translating foreign operations	(4,952,815)	(167,099)	(5,843,856)	11,459
Share of exchange difference of associates and joint venture accounted for using the equity method	(137,221)	(4,630)	(292,438)	(59,650)
Ending balance	$ (6,733,659)	$ (227,182)	$ (1,643,623)	$ 4,492,671

Equity - Summary of Unrealized

Equity - Summary of Unrealized Gain (Loss) on Available-for-sale Financial Assets (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Beginning balance	$ 166,841,165		$ 165,924,980	$ 155,691,394
Unrealized gain (loss) arising on revaluation of available-for-sale financial assets	224,036	$ 7,559	(248,599)	10,451
Share of unrealized gain (loss) on available-for-sale financial assets of associates and joint venture accounted for using the equity method	264,389	8,920	(871,679)	(4,832)
Ending balance	201,310,187	6,791,842	166,841,165	165,924,980
Reserve of gains and losses on remeasuring available-for-sale financial assets excluding changes in capital surplus [member]
Beginning balance	(197,314)	(6,657)	588,119	526,778
Unrealized gain (loss) arising on revaluation of available-for-sale financial assets	169,585	5,721	(257,240)	(4,304)
Cumulative loss reclassified to profit or loss on impairment of available-for-sale financial assets	50,206	1,694
Cumulative loss (gain) reclassified to profit or loss on disposal of available-for-sale financial assets	(1,517)	(51)	7,512	10,827
Share of unrealized gain (loss) on available-for-sale financial assets of associates and joint venture accounted for using the equity method	401,610	13,550	(535,705)	54,818
Ending balance	$ 422,570	$ 14,257	$ (197,314)	$ 588,119

Equity - Summary of Treasury Sh

Equity - Summary of Treasury Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Beginning balance	265,883	265,883	145,883
Addition			120,000
Decrease	0	0	0
Ending balance	265,883	265,883	265,883
Shares held by subsidiaries [member]
Beginning balance	145,883	145,883	145,883
Decrease	0	0	0
Ending balance	145,883	145,883	145,883
Shares reserved for bonds conversion [member]
Beginning balance	120,000	120,000
Addition			120,000
Decrease	0	0	0
Ending balance	120,000	120,000	120,000

Equity - Summary of Shares Held

Equity - Summary of Shares Held By Subsidiaries (Detail) shares in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016TWD ($)shares
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	145,883	145,883	145,883
Shares Held By Subsidiaries, Value	$ 1,959,107	$ 66,097	$ 1,959,107
Fair value [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	$ 5,565,437	$ 187,768	$ 4,821,434
ASE Test Limited [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	88,200	88,200	88,200
Shares Held By Subsidiaries, Value	$ 1,380,721	$ 46,583	$ 1,380,721
ASE Test Limited [member] | Fair value [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	$ 3,364,848	$ 113,524	$ 2,915,026
J & R Holding Limited [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	46,704	46,704	46,704
Shares Held By Subsidiaries, Value	$ 381,709	$ 12,878	$ 381,709
J & R Holding Limited [member] | Fair value [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	$ 1,781,749	$ 60,113	$ 1,543,559
ASE Test, Inc. [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	10,979	10,979	10,979
Shares Held By Subsidiaries, Value	$ 196,677	$ 6,636	$ 196,677
ASE Test, Inc. [member] | Fair value [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	$ 418,840	$ 14,131	$ 362,849

Equity - Summary of Non-control

Equity - Summary of Non-controlling Interests (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Beginning balance	$ 166,841,165		$ 165,924,980	$ 155,691,394
Share of profit for the year (Note 28)	1,677,941	$ 56,611	1,253,438	968,567
Exchange difference on translating foreign operations	(5,287,734)	(178,399)	(6,445,643)	(63,509)
Unrealized gain on available-for-sale financial assets	224,036	7,559	(248,599)	10,451
Defined benefit plan actuarial gains (losses)	205,344	6,928	(417,181)	(62,911)
Ending balance	201,310,187	6,791,842	166,841,165	165,924,980
Non-controlling interests [member]
Beginning balance	12,000,551	404,877	11,492,545	8,209,860
Share of profit for the year (Note 28)	1,677,941	56,611	1,253,438	968,567
Exchange difference on translating foreign operations	(334,920)	(11,300)	(601,787)	(74,968)
Unrealized gain on available-for-sale financial assets	5,763	194	1,129	3,928
Defined benefit plan actuarial gains (losses)	(13,724)	(463)	8,846	(3,440)
Non-controlling interests arising from acquisition of subsidiaries (Note 28)			42,857
Partial disposal of subsidiaries (Note 30)	(3,055)	(103)	26,436	1,712,836
Repurchase of outstanding ordinary shares of subsidiaries (Note 30)			(912,886)
Spin-off of subsidiaries				3,006
Non-controlling interest relating to outstanding vested employee share options held by the employees of subsidiaries	263,213	8,880	927,823	904,904
Non-controlling interest relating to outstanding expired employee share options	(159,200)	(5,371)
Cash dividends to non-controlling interests	(246,440)	(8,314)	(237,850)	(232,148)
Ending balance	$ 13,190,129	$ 445,011	$ 12,000,551	$ 11,492,545

Profit Before Income Tax - Summ

Profit Before Income Tax - Summary of Other Operating Income and Expenses, Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Analysis of income and expense [abstract]
Rental income	$ 131,570	$ 4,439	$ 51,607	$ 60,230
Gain (loss) on disposal of property, plant and equipment and other assets	367,110	12,386	(127,159)	(127,111)
Impairment loss on property, plant and equipment and goodwill	(714,675)	(24,112)	(888,231)	(258,129)
Loss on damages and claims	(85,585)	(2,888)	(12,778)	(116,445)
Others	410,136	13,837	176,281	189,926
Other operating income and expenses, net	$ 108,556	$ 3,662	$ (800,280)	$ (251,529)

Profit Before Income Tax - S144

Profit Before Income Tax - Summary of Other Income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Analysis of income and expense [abstract]
Government subsidy	$ 341,844	$ 11,533	$ 332,758	$ 176,721
Interest income	306,871	10,353	230,067	242,084
Dividends income	59,039	1,992	26,411	396,973
Other income	$ 707,754	$ 23,878	$ 589,236	$ 815,778

Profit Before Income Tax - S145

Profit Before Income Tax - Summary of Other Gains and Losses (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Analysis of income and expense [abstract]
Gain on disposal of subsidiaries (Note 29)	$ 5,589,457	$ 188,578
Net gain (loss) arising on financial instruments held for trading	(3,111,253)	(104,968)	$ 224,446	$ 1,657,093
Net gain on financial assets designated as at FVTPL	327,351	11,044	223,113	815,742
Foreign exchange gain or loss, net	3,502,586	118,171	1,928,384	(713,213)
Impairment loss on financial assets	(50,206)	(1,694)	(91,886)
Others	1,518	52	(7,513)	(10,827)
Other gains and losses	$ 6,259,453	$ 211,183	$ 2,276,544	$ 1,748,795

Profit Before Income Tax - S146

Profit Before Income Tax - Summary of Finance Costs (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Analysis of income and expense [abstract]
Total interest expense for financial liabilities measured at amortized cost	$ 2,016,298	$ 68,026	$ 2,510,197	$ 2,514,208
Less: Amounts included in the cost of qualifying assets
Inventories related to real estate business	(190,137)	(6,415)	(238,469)	(197,287)
Property, plant and equipment	(51,262)	(1,729)	(54,191)	(48,135)
Investment property	(13)
Interest expense	1,774,886	59,882	2,217,537	2,268,786
Other finance costs	24,608	830	43,538	43,357
Finance costs	$ 1,799,494	$ 60,712	$ 2,261,075	$ 2,312,143

Profit Before Income Tax - S147

Profit Before Income Tax - Summary of Capitalized Borrowing Costs (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Inventories related to real estate business [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest capitalization rates	4.35%	4.35%	4.35%
Inventories related to real estate business [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest capitalization rates	5.39%	6.00%	6.77%
Property, plant and equipment [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest capitalization rates	1.26%	1.15%	0.75%
Property, plant and equipment [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest capitalization rates	5.49%	4.42%	6.15%
Investment properties [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest capitalization rates	1.26%
Investment properties [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Annual interest capitalization rates	1.97%

Profit Before Income Tax - S148

Profit Before Income Tax - Summary of Depreciation and Amortization (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Analysis of income and expense [Line Items]
Property, plant and equipment depreciation	$ 28,747,518	$ 969,890	$ 28,961,614	$ 28,938,770
Investment properties	122,231	4,124
Intangible assets amortization	457,666	15,441	508,823	579,894
Depreciation and amortization	29,205,184	985,331	29,470,437	29,518,664
Operating costs [member]
Analysis of income and expense [Line Items]
Property, plant and equipment depreciation	26,731,714	901,880	26,948,106	27,023,957
Intangible assets amortization	140,175	4,729	152,987	124,235
Operating expenses [member]
Analysis of income and expense [Line Items]
Property, plant and equipment depreciation	2,015,804	68,010	2,013,508	1,914,813
Intangible assets amortization	$ 317,491	$ 10,712	$ 355,836	$ 455,659

Profit Before Income Tax - S149

Profit Before Income Tax - Summary of Operating Expenses Directly Related to Investment Properties (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Direct operating expense from investment property [abstract]
Direct operating expenses of investment properties that generated rental income	$ 465,458	$ 15,704

Profit Before Income Tax - S150

Profit Before Income Tax - Summary of Employee Benefits Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Post-employment benefits
Defined contribution plans	$ 2,340,826	$ 78,975	$ 2,356,416	$ 2,324,737
Defined benefit plans	266,267	8,983	394,741	413,490
Post-employment benefits	2,607,093	87,958	2,751,157	2,738,227
Equity-settled share-based payments	438,765	14,803	470,788	133,496
Other employee benefits	51,043,198	1,722,105	49,525,940	47,883,464
Employee benefits expense	54,089,056	1,824,866	52,747,885	50,755,187
Operating costs [member]
Post-employment benefits
Employee benefits expense	35,978,403	1,213,846	35,588,529	34,720,359
Operating expenses [member]
Post-employment benefits
Employee benefits expense	$ 18,110,653	$ 611,020	$ 17,159,356	$ 16,034,828

Profit Before Income Tax - Addi

Profit Before Income Tax - Additional Information (Detail) $ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015
Analysis of income and expense [Line Items]
Percentage of employees' compensation		8.25%	8.25%	8.25%	8.25%
Percentage of remuneration to directors		0.75%	0.75%	0.75%	0.75%
Difference between paid and recognized value of employees' compensation and remuneration to directors		$ 42,634	$ 1,438	$ 44,200
Bottom of range [member]
Analysis of income and expense [Line Items]
Percentage of employees' compensation	5.25%
Top of range [member]
Analysis of income and expense [Line Items]
Percentage of employees' compensation	8.25%

Profit Before Income Tax - S152

Profit Before Income Tax - Summary of Employees' Compensation and Remuneration to Directors (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Analysis of income and expense [Line Items]
Employees' compensation	$ 2,291,140	$ 77,299	$ 2,147,323	$ 2,033,500
Remuneration to directors	$ 208,285	$ 7,027	195,211	184,500
Resolved by the board of directors [member]
Analysis of income and expense [Line Items]
Employees' compensation			2,151,900	2,033,800
Remuneration to directors			$ 148,000	$ 140,000

Income Tax - Summary of Major C

Income Tax - Summary of Major Components of Income Tax Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Current income tax
In respect of the current year	$ 4,979,766	$ 168,008	$ 4,177,900	$ 4,029,076
Income tax on unappropriated earnings	1,076,353	36,314	829,345	187,654
Changes in estimate for prior years	(88,162)	(2,974)	28,160	(20,719)
Current income tax	5,967,957	201,348	5,035,405	4,196,011
Deferred income tax
In respect of the current year	534,472	18,032	574,541	190,829
Adjustments attributable to changes in tax rates			14,184	3,794
Changes in estimate for prior years	52,872	1,784	(206,788)	(20,890)
Effect of foreign currency exchange differences	(31,698)	(1,070)	(26,498)	(58,671)
Deferred income tax	555,646	18,746	355,439	115,062
Income tax expense recognized in profit or loss	$ 6,523,603	$ 220,094	$ 5,390,844	$ 4,311,073

Income Tax - Summary of Reconci

Income Tax - Summary of Reconciliation of Income Tax Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Major components of tax expense (income) [abstract]
Profit before income tax	$ 31,020,663	$ 1,046,581	$ 27,968,705	$ 25,011,788
Income tax expense calculated at the statutory rates	10,890,498	367,426	8,634,187	6,307,148
Nontaxable expense in determining taxable income	483,715	16,319	(34,954)	160,530
Tax-exempt income	(623,566)	(21,038)	(700,274)	(537,987)
Additional income tax on unappropriated earnings	1,076,353	36,314	829,345	338,142
Loss carry-forward and income tax credits currently used	(1,124,043)	(37,923)	(898,700)	(1,286,705)
Remeasurement of deferred income tax assets, net	(4,131,473)	(139,389)	(2,797,673)	(688,584)
Changes in estimate for prior years	(88,162)	(2,974)	28,160	(20,719)
Withholding tax	40,281	1,359	81,543	39,248
Land value increment tax			249,210
Income tax expense recognized in profit or loss	$ 6,523,603	$ 220,094	$ 5,390,844	$ 4,311,073

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) $ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2018	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015	Dec. 31, 2017USD ($)
Disclosure of income taxes [line items]
Applied tax rate	20.00%	17.00%	17.00%	17.00%	17.00%
Income tax on unappropriated earnings	5.00%	10.00%	10.00%
Increase in deferred tax assets		$ 201,965	$ 6,814
Increase in deferred tax liabilities		788,556				$ 26,604
Taxable temporary differences associated with the investments in subsidiaries for which no deferred tax liabilities recognized		16,401,422		$ 14,417,873		553,354
Balance of Imputation Credit Account		$ 4,003,283		$ 3,328,374		$ 135,064
Ratio of distribution of earnings				10.01%
Subsidiaries [member] | China [member]
Disclosure of income taxes [line items]
Applied tax rate		25.00%	25.00%	25.00%	25.00%
Reduction tax rate		15.00%	15.00%

Income Tax - Summary of Income

Income Tax - Summary of Income Tax Recognized Directly in Equity (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Current and deferred tax relating to items charged or credited directly to equity [abstract]
Deferred income tax related to employee share options	$ 262	$ 9	$ (204)	$ (33)

Income Tax - Summary of Inco157

Income Tax - Summary of Income Tax Recognized in Other Comprehensive Income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Income tax relating to components of other comprehensive income [abstract]
Deferred income tax related to remeasurement of defined benefit plans	$ (51,217)	$ (1,728)	$ 73,637	$ 11,002

Income Tax - Summary of Current

Income Tax - Summary of Current Tax Assets and Liabilities (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Current tax assets
Tax refund receivable	$ 28,458	$ 960	$ 260,559
Prepaid income tax	232,084	7,830	211,193
Current tax assets	260,542	8,790	471,752
Current tax liabilities
Income tax payable	$ 7,619,328	$ 257,062	$ 6,846,350

Income Tax - Summary of Movemen

Income Tax - Summary of Movements of Deferred Tax Assets and Deferred Tax Liabilities (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	$ (319,625)	$ (10,784)	$ 168,966	$ 332,401
Recognized in Profit or Loss	(555,646)	(18,746)	(355,439)	(115,062)
Recognized in Other Comprehensive Income	(51,217)	(1,728)	73,637	11,002
Recognized in Equity	262	9	(204)	(33)
Exchange Differences	(33,440)	(1,129)	(209,524)	(59,342)
Acquisitions through business combinations			2,939
Balance at December 31	(959,666)	(32,378)	(319,625)	168,966
Property, plant and equipment [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	(3,758,847)	(126,817)	(3,504,458)	(2,431,855)
Recognized in Profit or Loss	(101,576)	(3,427)	(182,291)	(1,083,273)
Exchange Differences	(18,643)	(629)	(72,098)	10,670
Balance at December 31	(3,879,066)	(130,873)	(3,758,847)	(3,504,458)
Defined benefit obligation [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	873,484	29,470	845,939	796,642
Recognized in Profit or Loss	(26,736)	(902)	(48,601)	20,398
Recognized in Other Comprehensive Income	(51,217)	(1,728)	73,637	11,002
Exchange Differences	(15,291)	(516)	2,509	17,897
Balance at December 31	780,240	26,324	873,484	845,939
FVTPL financial instruments [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	(21,363)	(721)	(232,198)	(170,059)
Recognized in Profit or Loss	(86,342)	(2,913)	212,737	(62,152)
Exchange Differences	2,802	94	(1,902)	13
Balance at December 31	(104,903)	(3,540)	(21,363)	(232,198)
Other temporary differences [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	1,079,824	36,431	1,384,987	1,166,297
Recognized in Profit or Loss	(22,748)	(767)	(283,179)	229,799
Recognized in Equity	262	9	(204)	(33)
Exchange Differences	(28,929)	(976)	(21,780)	(11,076)
Balance at December 31	1,028,409	34,697	1,079,824	1,384,987
Temporary differences [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	(1,826,902)	(61,637)	(1,505,730)	(638,975)
Recognized in Profit or Loss	(237,402)	(8,009)	(301,334)	(895,228)
Recognized in Other Comprehensive Income	(51,217)	(1,728)	73,637	11,002
Recognized in Equity	262	9	(204)	(33)
Exchange Differences	(60,061)	(2,027)	(93,271)	17,504
Balance at December 31	(2,175,320)	(73,392)	(1,826,902)	(1,505,730)
Unused tax losses [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	1,124,541	37,940	1,323,577	519,898
Recognized in Profit or Loss	(456,246)	(15,393)	(110,967)	812,217
Exchange Differences	13,146	444	(91,008)	(8,538)
Acquisitions through business combinations			2,939
Balance at December 31	681,441	22,991	1,124,541	1,323,577
Unused tax credits [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1	382,736	12,913	351,119	452,331
Recognized in Profit or Loss	138,002	4,656	56,862	(32,904)
Exchange Differences	13,475	454	(25,245)	(68,308)
Balance at December 31	$ 534,213	$ 18,023	$ 382,736	351,119
Others [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Balance at January 1				(853)
Recognized in Profit or Loss				$ 853

Income Tax - Summary of Unrecog

Income Tax - Summary of Unrecognized Deferred Tax Assets Related to Loss Carry-forward, Investment Credits and Deductible Temporary Differences (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of temporary difference, unused tax losses and unused tax credits [abstract]
Loss carry-forward	$ 542,054	$ 18,288	$ 652,593
Investment credits			280,068
Deductible temporary differences	712,141	24,026	904,441
Unrecognized deferred tax assets	$ 1,254,195	$ 42,314	$ 1,837,102

Income Tax - Summary of Unused

Income Tax - Summary of Unused Loss Carry-forward (Detail) - Dec. 31, 2017 - Unused tax losses [member] $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused loss carry-forward	$ 1,223,495	$ 41,279
2018 [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused loss carry-forward	230,656	7,782
2019 [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused loss carry-forward	34,981	1,180
2020 [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused loss carry-forward	615,327	20,760
2021 [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused loss carry-forward	164,377	5,546
2022 and thereafter [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused loss carry-forward	$ 178,154	$ 6,011

Income Tax - Summary of Unus162

Income Tax - Summary of Unused Investment Credits (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Unused tax credits [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Remaining Creditable Amount	$ 534,213	$ 18,023
Purchase of machinery and equipment [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Expiry Year	2,018
Purchase of machinery and equipment [member] | Unused tax credits [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Remaining Creditable Amount	$ 518,790	17,503
Others [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Expiry Year	2,022 and thereafter
Others [member] | Unused tax credits [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Remaining Creditable Amount	$ 15,423	$ 520

Income Tax - Summary of Project

Income Tax - Summary of Projects were Exempted From Income Tax (Detail)	12 Months Ended
	Dec. 31, 2017
Construction and expansion of 2007 by the company [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax-exemption period, start date	2016-01
Tax-exemption period, end date	2020-12
Construction and expansion of 2008 [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax-exemption period, start date	2014-01
Tax-exemption period, end date	2018-12
Construction and expansion of 2008 [member] | ASE Test, Inc. [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax-exemption period, start date	2014-01
Tax-exemption period, end date	2018-12
Construction and expansion of 2009 [member] | ASE Test, Inc. [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax-exemption period, start date	2018-01
Tax-exemption period, end date	2022-12
Expansion of 2008 [member] | ASE Electronics Inc. [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax-exemption period, start date	2016-01
Tax-exemption period, end date	2020-12

Earnings Per Share - Summary of

Earnings Per Share - Summary of Earnings and Weighted Average Number of Ordinary Shares Outstanding in Computation of Earnings Per Share (Detail) shares in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016TWD ($)shares	Dec. 31, 2015TWD ($)shares
Earnings per share [abstract]
Profit for the year attributable to owners of the Company	$ 22,819,119	$ 769,876	$ 21,324,423	$ 19,732,148
Effect of potentially dilutive ordinary shares:
Employee share options issued by subsidiaries	(813,627)	(27,450)	(374,359)
Investments in associates	(367,687)	(12,405)	(494,388)	(210,126)
Convertible bonds	93,781	3,164	(1,165,506)	901,187
Earnings used in the computation of diluted earnings per share	$ 21,731,586	$ 733,185	$ 19,290,170	$ 20,423,209
Weighted average number of ordinary shares in computation of basic earnings per share	8,160,887	8,160,887	7,662,870	7,652,773
Effect of potentially dilutive ordinary shares:
Convertible bonds	124,911	124,911	515,295	455,671
Employee share options	39,868	39,868	59,218	86,994
Employees' compensation	43,574	43,574	46,746	54,626
Weighted average number of ordinary shares in computation of diluted earnings per share	8,369,240	8,369,240	8,284,129	8,250,064

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
American depository shares (ADs) [member]
Earnings per share [line items]
Number of ordinary shares per ADS	5

Share-based Payment Arrangem166

Share-based Payment Arrangements - Additional Information (Detail) $ / shares in Units, $ / shares in Units, shares in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)yr$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016TWD ($)yr$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015TWD ($)$ / shares	Dec. 31, 2007shares	Dec. 31, 2017USD ($)yr
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Compensation cost of employee share options	$ 438,765	$ 14,803	$ 470,788		$ 133,496
USISH option plans [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Valid term of share option plans	10 years	10 years
Remaining contractual life of share options | yr	7.9		8.9				7.9
USIE option plans [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Capital surplus decreased	$ 52,388		$ 444,320				$ 1,767
Incremental fair value granted, modified share-based payment arrangements | $					$ 13,721
ASE Inc. option plans [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Valid term of share option plans	10 years	10 years
Weighted average exercise price of share options | (per share)	$ 37.60	$ 1.27	$ 36.20		$ 38.80
Reclassification from capital surplus arising from exercised employee share options to capital surplus arising from expired employee share options	$ 47,087	$ 1,589
ASE Mauritius Inc. option plan [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Valid term of share option plans	10 years	10 years
Number of shares granted						30,000
Reclassification from non-controlling interest to capital surplus arising from expired employee share options	$ 159,200	$ 5,371
New shares reserved for subscription by employees under cash capital increase [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Options granted to employees to purchase newly issued shares, percentage			10.00%	10.00%
Employee benefits expense and capital surplus arising from exercised employee share option			$ 84,000	$ 2,834
Number of shares has not been exercised			4,836	4,836
Amount reclassified from capital surplus arising from exercised employee share options to capital surplus arising from expired employee share options			$ 13,541	$ 457

Share-based Payment Arrangem167

Share-based Payment Arrangements - Summary of Information About ASE Inc. Option Plans (Detail) - ASE Inc. option plans [member] shares in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)shares	Dec. 31, 2016TWD ($)shares	Dec. 31, 2015TWD ($)shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of options, beginning balance | shares	210,795	252,607	209,745
Number of options, granted | shares			94,270
Number of options, forfeited | shares	(5,407)	(6,056)	(1,975)
Number of options, expired | shares	(1,790)		(730)
Number of options, exercised | shares	(67,637)	(35,756)	(48,703)
Number of options, ending balance | shares	135,961	210,795	252,607
Number of options, exercisable, end of year | shares	85,642	123,007	158,103
Weighted average exercise price, Beginning balance	$ 27.3	$ 26.6	$ 20.7
Weighted average exercise price, Options granted			36.5
Weighted average exercise price, Options forfeited	36.3	34.6	30.3
Weighted average exercise price, Options expired	21.1		11.1
Weighted average exercise price, Options exercised	21	20.9	20.6
Weighted average exercise price, Ending balance	30.2	27.3	26.6
Weighted average exercise price, Options exercisable, end of year	$ 26.5	$ 20.8	20.8
Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted-average fair value of options granted (NT$)			7.18
Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted-average fair value of options granted (NT$)			$ 7.39

Share-based Payment Arrangem168

Share-based Payment Arrangements - Summary of ASE Inc. Option Plans Outstanding Share Options (Detail) - ASE Inc. option plans [member]	Dec. 31, 2017TWD ($)yr	Dec. 31, 2016TWD ($)yr
Fourth share options exercise price [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted Average Remaining Contractual Life (Years) | yr	2.5	2.5
Fifth share options exercise price [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Range of Exercise Price Per Share	$ 36.5	$ 36.5
Weighted Average Remaining Contractual Life (Years) | yr	7.7	8.7
Bottom of range [member] | Fourth share options exercise price [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Range of Exercise Price Per Share	$ 20.4	$ 20.4
Top of range [member] | Fourth share options exercise price [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Range of Exercise Price Per Share	$ 22.6	$ 22.6

Share-based Payment Arrangem169

Share-based Payment Arrangements - Summary of Information About ASE Mauritius Inc. Option Plan (Detail) - ASE Mauritius Inc. option plan [member] shares in Thousands, pure in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of options, beginning balance | shares	28,470	28,470	28,545
Number of options, forfeited | shares	(250)		(75)
Number of options, Expired	(28,220)
Number of options, ending balance | shares		28,470	28,470
Number of options, exercisable, end of year | shares		28,470	28,470
Weighted average exercise price, Beginning balance	$ 1.7	$ 1.7	$ 1.7
Weighted average exercise price, Options forfeited	1.7		1.7
Weighted average exercise price, Options expired	$ 1.7
Weighted average exercise price, Ending balance		1.7	1.7
Weighted average exercise price, Options exercisable, end of year		$ 1.7	$ 1.7

Share-based Payment Arrangem170

Share-based Payment Arrangements - Summary of Information About USIE Option Plans (Detail) - USIE option plans [member] shares in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of options, beginning balance | shares	25,933	29,695	34,159
Number of options, forfeited | shares			(84)
Number of options, exercised | shares	(377)	(3,762)	(4,380)
Number of options, ending balance | shares	25,556	25,933	29,695
Number of options, exercisable, end of year | shares	25,556	25,933	28,106
Weighted average exercise price, Beginning balance | $	$ 2.2	$ 2.1	$ 2.1
Weighted average exercise price, Options forfeited | $			2.8
Weighted average exercise price, Options exercised | $	1.9	2	1.9
Weighted average exercise price, Ending balance | $	2.2	2.2	2.1
Weighted average exercise price, Options exercisable, end of year | $	$ 2.2	$ 2.2	$ 2.1

Share-based Payment Arrangem171

Share-based Payment Arrangements - Summary of USIE Option Plans Outstanding Share Options (Detail) - USIE option plans [member]	Dec. 31, 2017USD ($)yr	Dec. 31, 2016USD ($)yr
First share options exercise price [member]
Disclosure of range of exercise prices of outstanding share options [Line Items]
Range of Exercise Price Per Share	$ 1.5	$ 1.5
Weighted Average Remaining Contractual Life (Years) | yr	3	4
Second and third share options exercise price [member]
Disclosure of range of exercise prices of outstanding share options [Line Items]
Weighted Average Remaining Contractual Life (Years) | yr	2.9	3.9
Second and third share options exercise price [member] | Bottom of range [member]
Disclosure of range of exercise prices of outstanding share options [Line Items]
Range of Exercise Price Per Share	$ 2.4	$ 2.4
Second and third share options exercise price [member] | Top of range [member]
Disclosure of range of exercise prices of outstanding share options [Line Items]
Range of Exercise Price Per Share	$ 2.9	$ 2.9

Share-based Payment Arrangem172

Share-based Payment Arrangements - Summary of Information About USISH Option Plans (Detail) - USISH option plans [member] shares in Thousands	12 Months Ended
	Dec. 31, 2017CNY (¥)shares	Dec. 31, 2016CNY (¥)shares	Dec. 31, 2015CNY (¥)shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of options, beginning balance | shares	24,997	26,627
Number of options, granted | shares			26,640
Number of options, forfeited | shares	(2,656)	(1,630)	(13)
Number of options, ending balance | shares	22,341	24,997	26,627
Number of options, exercisable, end of year | shares	8,896
Weighted average exercise price, Beginning balance | ¥	¥ 15.5	¥ 15.5
Weighted average exercise price, Options granted | ¥			¥ 15.5
Weighted average exercise price, Options forfeited | ¥	15.5	15.5	15.5
Weighted average exercise price, Ending balance | ¥	15.5	¥ 15.5	¥ 15.5
Weighted average exercise price, Options exercisable, end of year | ¥	¥ 15.5

Share-based Payment Arrangem173

Share-based Payment Arrangements - Summary of Inputs Related to Fair Value of Share Options (Detail) - 12 months ended Dec. 31, 2017	TWD ($)yr	CNY (¥)yr
ASE Inc. option plans [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share price at the grant date | $	$ 36.5
Exercise prices | $	$ 36.5
Expected volatility	27.02%	27.02%
Expected lives | yr	10	10
Expected dividend yield	4.00%	4.00%
Risk free interest rates	1.34%	1.34%
USISH option plans [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share price at the grant date | ¥		¥ 15.2
Exercise prices | ¥		¥ 15.5
Expected lives | yr	10	10
Expected dividend yield	0.87%	0.87%
USISH option plans [member] | Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Expected volatility	40.33%	40.33%
Risk free interest rates	3.06%	3.06%
USISH option plans [member] | Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Expected volatility	45.00%	45.00%
Risk free interest rates	3.13%	3.13%

Share-based Payment Arrangem174

Share-based Payment Arrangements - Summary of Information About New Shares Reserved for Subscription by Employees under Cash Capital Increase Option Plans (Detail) - New shares reserved for subscription by employees under cash capital increase [member] shares in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of options, granted	30,000
Number of options, exercised	25,164
Weighted-average fair value of options granted (NT$ per share) | $	$ 2.80

Share-based Payment Arrangem175

Share-based Payment Arrangements - Summary of Inputs Related to Fair Value of New Shares Reserved for Subscription by Employees under Cash Capital Increase Share Options (Detail) - New shares reserved for subscription by employees under cash capital increase [member]	12 Months Ended
	Dec. 31, 2017TWD ($)d
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share price at the grant date	$ 36.55
Exercise price	$ 34.30
Expected volatility	27.15%
Expected lives | d	47
Expected dividend yield	0.00%
Risk free interest rate	0.37%

Business Combinations - Summary

Business Combinations - Summary of Subsidiary Acquired (Detail) - TLJ Intertech Inc. [member] - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Disclosure of detailed information about business combination [Line Items]
Principal Activity	Engaged in information software services
Date of Acquisition	May 3, 2016
Proportion of Voting Equity Interests Acquired	60.00%		60.00%
Cash Consideration	$ 89,998	$ 89,998

Business Combinations - Additio

Business Combinations - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	May 31, 2016
Disclosure of subsidiaries [Line Items]
Decrease in retained earnings due to retrospective adjustments	$ (28,880)
Increase in non-controlling interests due to retrospective adjustments	16,583
TLJ Intertech Inc. [member]
Disclosure of subsidiaries [Line Items]
Percentage of shareholdings acquired by subsidiary		60.00%	60.00%
Total consideration was paid to key management personnel and related parties	$ 89,998	$ 89,998
TLJ Intertech Inc. [member] | Related parties [member]
Disclosure of subsidiaries [Line Items]
Total consideration was paid to key management personnel and related parties			$ 41,739

Business Combinations - Summ178

Business Combinations - Summary of Assets Acquired and Liabilities Assumed at the Date of Acquisition (Detail) - TLJ Intertech Inc. [member] $ in Thousands	Dec. 31, 2017TWD ($)
Disclosure of detailed information about business combination [Line Items]
Current assets	$ 16,645
Non-current assets	108,486
Current liabilities	(7,599)
Fair value of identifiable net assets acquired	$ 117,532

Business Combinations - Summ179

Business Combinations - Summary of Goodwill Recognized on Acquisition (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Disclosure of detailed information about business combination [Line Items]
Goodwill recognized on acquisition	$ 9,934,494	$ 335,172	$ 10,490,309	$ 353,924	$ 10,506,519	$ 10,445,415
TLJ Intertech Inc. [member]
Disclosure of detailed information about business combination [Line Items]
Consideration transferred (paid in cash)	89,998		$ 89,998
Add: Non-controlling interests	42,857
Less: Fair value of identifiable net assets acquired	(117,532)
Goodwill recognized on acquisition	$ 15,323

Business Combinations - Summ180

Business Combinations - Summary of Net Cash Outflow on Acquisition of Subsidiaries (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about business combination [Line Items]
Less: Cash acquired	$ (29,133)	$ (983)
Net cash outflow on acquisition of subsidiaries	(7,046,464)	$ (237,735)
TLJ Intertech Inc. [member]
Disclosure of detailed information about business combination [Line Items]
Consideration paid in cash	$ 89,998		$ 89,998
Less: Cash acquired			(16,561)
Net cash outflow on acquisition of subsidiaries			$ 73,437

Business Combinations - Summ181

Business Combinations - Summary of Retrospective Adjustments of Intangible Assets (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2014TWD ($)
Disclosure of detailed information about business combination [Line Items]
Goodwill	$ 9,934,494		$ 10,490,309	$ 10,506,519	$ 335,172	$ 353,924	$ 10,445,415
Other intangible assets	1,406,865		1,617,261		$ 47,465
OPERATING COSTS	$ 237,708,937	$ 8,019,870	221,696,922	$ 233,167,308
Operating expenses			26,526,815
Previously stated [member]
Disclosure of detailed information about business combination [Line Items]
Goodwill			10,558,878
Other intangible assets			1,560,989
OPERATING COSTS			221,689,888
Operating expenses			$ 26,485,716

Disposal of Subsidiaries - Summ

Disposal of Subsidiaries - Summary of Gain on Disposal of Subsidiaries (Detail) $ in Thousands, $ in Thousands	1 Months Ended		12 Months Ended
	Jun. 30, 2017TWD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)
Disclosure of gain from disposals of subsidiaries [Line Items]
Total consideration			$ (7,046,464)	$ (237,735)
KSDY [member]
Disclosure of gain from disposals of subsidiaries [Line Items]
Total consideration	$ 7,046,464	$ 237,735
Net assets disposed of	(1,457,007)	(49,157)
Gain on disposal of KSDY	$ 5,589,457	$ 188,578

Disposal of Subsidiaries - S183

Disposal of Subsidiaries - Summary of Analysis of Assets and Liabilities on Date Control was Lost (Detail) - 1 months ended Jun. 30, 2017 - KSDY [member] $ in Thousands, $ in Thousands	TWD ($)	USD ($)	USD ($)
Current assets
Cash and cash equivalents	$ 29,133		$ 983
Inventories related to real estate business	1,427,874		$ 48,174
Net assets disposed of	$ 1,457,007	$ 49,157

Equity Transaction with Non-184

Equity Transaction with Non-controlling Interests - Additional Information (Detail) $ / shares in Units, $ / shares in Units, ¥ in Thousands, shares in Thousands, $ in Thousands, $ in Thousands	1 Months Ended								12 Months Ended
	Jan. 31, 2018$ / sharesshares	Jan. 31, 2017TWD ($)	Jan. 31, 2017USD ($)	Feb. 29, 2016shares	Feb. 28, 2016TWD ($)$ / sharesshares	Jan. 31, 2016	Apr. 30, 2015CNY (¥)shares	Mar. 31, 2015	Dec. 31, 2017TWD ($)$ / sharesshares	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)shares	Oct. 13, 2017shares	Jul. 13, 2017shares	Dec. 31, 2016TWD ($)	Jun. 30, 2015TWD ($)
Sale of shares												323,094	101,164
Proceeds from issuance of shares									$ 10,290,000	$ 347,166
Cash capital increase [member]
Sale of shares									300,000		300,000
Sale of shares per share | $ / shares									$ 34.3
USI Enterprise Limited [member]
Increase (decrease) in capital surplus | $														$ (1,912,887)	$ 7,197,510
Number of shares repurchased				4,501
Percentage of increase in shareholdings				98.80%		96.70%
Number of shares approved for repurchase	3,738,420
Shares repurchase price per share | $ / shares	$ 17.49
Universal Scientific Industrial (Shanghai) Co., Ltd [member] | USI Enterprise Limited [member]
Proceeds from issuance of shares | ¥							¥ 1,992,060
Universal Scientific Industrial (Shanghai) Co., Ltd [member] | USI Enterprise Limited [member] | Ordinary shares [member]
Sale of shares							54,000
Percentage of decrease in shareholdings							77.20%	82.10%
Universal Global Scientific Industrial Co., Ltd. [member] | USI [member]
Sale of shares					39,603
Percentage of decrease in shareholdings					76.50%	99.00%
Increase (decrease) in capital surplus | $														$ (20,552)
Sale of shares per share | $ / shares					$ 20
Proceeds from issuance of shares | $					$ 792,064
USI [member]
Increase (decrease) in capital surplus									$ 3,055		$ 103
Percentage of increase in shareholdings		75.20%	75.20%
Cash capital increase amount		$ 1,000,000	$ 33,738
USI [member] | Cash capital increase [member]
Percentage of increase in shareholdings		75.70%	75.70%

Non-cash Transactions - Summary

Non-cash Transactions - Summary of Non-cash Investing Activities (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Payments for property, plant and equipment
Purchase of property, plant and equipment	$ 23,677,682	$ 798,842	$ 27,680,862	$ 28,280,821
Increase (decrease) in prepayments for property, plant and equipment (recorded under the line item of other non-current assets)	90,560	3,055	(89,337)	(267,334)
(Increase) decrease in payables for property, plant and equipment (recorded under the line item of other payables)	982,260	33,140	(823,171)	2,314,772
Capitalized borrowing costs	(51,262)	(1,729)	(54,191)	(48,135)
Payments for property, plant and equipment	24,699,240	833,308	26,714,163	30,280,124
Proceeds from disposal of property, plant and equipment
Consideration from disposal of property, plant and equipment	1,487,334	50,180	692,826	201,766
(Increase) decrease in other receivables	876	30	(22,626)	41,265
Proceeds from disposal of property, plant and equipment	1,488,210	50,210	670,200	243,031
Payments for investment properties
Purchase of investment properties	186,535	6,293
Capitalized borrowing costs	(13)
Proceeds from disposals of investment property	186,522	6,293
Payments for other intangible assets
Purchase of other intangible assets	277,825	9,373	675,144	491,135
Decrease (increase) in other payables	60,159	2,030	(120,938)
Increase in other non-current liabilities			(40,313)
Purchase of intangible assets classified as investing activities	337,984	11,403	$ 513,893	$ 491,135
Net cash inflow from disposal of subsidiaries
Consideration from disposal of subsidiaries	7,046,464	237,735
Increase in other payables	3,552	120
Cash and cash equivalents disposed of	(29,133)	(983)
Net cash inflow from disposal of subsidiaries	$ 7,020,883	$ 236,872

Non-cash Transactions - Additio

Non-cash Transactions - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2015TWD ($)
Disclosure Of Non Cash Investing Activities [Line Items]
Issue of ordinary shares under conversion of bonds	$ 13,900,482		$ 214,022
Share capital [member]
Disclosure Of Non Cash Investing Activities [Line Items]
Issue of ordinary shares under conversion of bonds	4,242,577	$ 143,137
Capital surplus [member]
Disclosure Of Non Cash Investing Activities [Line Items]
Issue of ordinary shares under conversion of bonds	$ 9,657,905	$ 325,840	$ 214,022

Operating Lease Arrangements -

Operating Lease Arrangements - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Lease and sublease payments recognised as expense [abstract]
Operating lease expiration	2018 to 2023	2018 to 2023
Rental expense	$ 1,193,477	$ 40,266	$ 1,411,533	$ 1,390,821

Operating Lease Arrangements188

Operating Lease Arrangements - Summary of Future Minimum Lease Payments of Non-cancellable Operating Lease Commitments (Detail) - Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments of non-cancellable operating lease commitments	$ 1,104,666	$ 37,269
Less than 1 year [member]
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments of non-cancellable operating lease commitments	246,026	8,300
1-5 years [member]
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments of non-cancellable operating lease commitments	439,408	14,825
More than 5 years [member]
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments of non-cancellable operating lease commitments	$ 419,232	$ 14,144

Financial Instruments - Summary

Financial Instruments - Summary of Fair Value of Financial Instruments Not Measured at Fair Value but for Which Fair Value is Disclosed (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about financial instruments [line items]
Bonds payable	$ 23,142,780	$ 780,796	$ 36,999,903
Fair value [member]
Disclosure of detailed information about financial instruments [line items]
Bonds payable	$ 23,247,085	$ 784,315	$ 37,300,356

Financial Instruments - Summ190

Financial Instruments - Summary of Fair Value of Financial Instruments that are Measured at Fair Value on a Recurring Basis (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about financial instruments [line items]
Financial assets designated as at FVTPL	$ 100,496	$ 3,391	$ 100,583
Financial assets held for trading	5,122,571	172,826	2,969,229
Financial liabilities at FVTPL	677,430	22,855	1,763,660
Financial assets at fair value through profit or loss	5,223,067	176,217	3,069,812
Available-for-sale financial assets	1,212,165	40,896	1,295,034
Level 1 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets at fair value through profit or loss	5,000,708	168,715	2,440,018
Available-for-sale financial assets	303,616	10,244	390,244
Level 2 of fair value hierarchy [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities at FVTPL	677,430	22,855	1,763,660
Financial assets at fair value through profit or loss	222,359	7,502	629,794
Level 3 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	908,549	30,652	904,790
Private-placement convertible bonds [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets designated as at FVTPL	100,496	3,391	100,583
Private-placement convertible bonds [member] | Level 2 of fair value hierarchy [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets designated as at FVTPL	100,496	3,391	100,583
Forward exchange contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	61,325	2,069	462,339
Financial liabilities at FVTPL	25,323	854	108,912
Forward exchange contracts [member] | Level 2 of fair value hierarchy [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	61,325	2,069	462,339
Financial liabilities at FVTPL	25,323	854	108,912
Swap contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	60,538	2,042	462,339
Financial liabilities at FVTPL	652,107	22,001	422,934
Swap contracts [member] | Level 2 of fair value hierarchy [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	60,538	2,042
Financial liabilities at FVTPL	652,107	22,001	422,934
Quoted shares [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	4,410,732	148,810	1,855,073
Quoted shares [member] | Level 1 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	4,410,732	148,810	1,855,073
Open-end mutual funds [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	589,976	19,905	584,945
Available-for-sale financial assets	23,825	804	243,458
Open-end mutual funds [member] | Level 1 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading	589,976	19,905	584,945
Available-for-sale financial assets	23,825	804	243,458
Unquoted shares [Member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	662,477	22,350	631,418
Unquoted shares [Member] | Level 3 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	662,477	22,350	631,418
Limited partnership [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	246,072	8,302	273,372
Limited partnership [member] | Level 3 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	246,072	8,302	273,372
Quoted ordinary shares [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	279,791	9,440	146,786
Quoted ordinary shares [member] | Level 1 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets	$ 279,791	$ 9,440	146,786
Foreign currency option contracts [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading			66,872
Financial liabilities at FVTPL			17,924
Foreign currency option contracts [member] | Level 2 of fair value hierarchy [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets held for trading			66,872
Financial liabilities at FVTPL			17,924
Conversion option, redemption option and put option of convertible bonds [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities at FVTPL			1,213,890
Conversion option, redemption option and put option of convertible bonds [member] | Level 2 of fair value hierarchy [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities at FVTPL			$ 1,213,890

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2017USD ($)
Disclosure of detailed information about financial instruments [line items]
Transfers between levels	$ 0		$ 0
Impairment loss	$ (714,675)	$ (24,112)	$ (888,231)	$ (258,129)
Floating interest rate [member]
Disclosure of detailed information about financial instruments [line items]
Increase decrease in basis points	1.00%	1.00%	1.00%	1.00%
Increase decrease in profit before tax	$ 24,000	$ 810	$ 358,000	$ 117,000
Currency risk [member]
Disclosure of detailed information about financial instruments [line items]
Value at risk	101,000		69,000	18,000	$ 3,408
Other price risk [member]
Disclosure of detailed information about financial instruments [line items]
Increase decrease in profit before tax	$ 52,000	$ 1,754	26,000	7,100
Equity debt ratio	1.00%	1.00%
Increase decrease in other comprehensive income	$ 13,000	$ 439	13,000	10,000
Decrease in profit before income tax			510,000	605,000
Increase in profit before income tax			445,000	$ 638,000
Other Gains and Losses Net [member]
Disclosure of detailed information about financial instruments [line items]
Impairment loss	$ 50,206	$ 1,694	$ 90,000

Financial Instruments - Summ192

Financial Instruments - Summary of Financial Assets Measured at Level 3 Fair Value (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of fair value measurement of assets [line items]
Beginning Balance	$ 357,930,576		$ 364,986,892
Ending Balance	363,922,272	$ 12,278,079	357,930,576	$ 364,986,892
Level 3 of fair value hierarchy [member] | Financial assets available-for-sale, category [member]
Disclosure of fair value measurement of assets [line items]
Beginning Balance	904,790	30,526	741,089	778,866
Purchases	2,649	89	495,928	2,010
Total gain or loss in profit or loss	28	1	(100,734)	(15,891)
Total gain or loss in other comprehensive income	17,284	583	(202,565)	21,195
Disposals	(16,202)	(547)	(28,928)	(45,091)
Ending Balance	$ 908,549	$ 30,652	$ 904,790	$ 741,089

Financial Instruments - Summ193

Financial Instruments - Summary of Categories of Financial Instruments (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about financial instruments [abstract]
Designated as at FVTPL	$ 100,496	$ 3,391	$ 100,583
Held for trading	5,122,571	172,826	2,969,229
Available-for-sale financial assets	1,212,165	40,896	1,295,034
Loans and receivables (Note 1)	103,973,567	3,507,881	92,082,628
Held for trading	677,430	22,855	1,763,660
Measured at amortized cost (Note 2)	$ 139,561,999	$ 4,708,569	$ 168,397,006

Financial Instruments - Summ194

Financial Instruments - Summary of Interest Rate Risk (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Fair value interest rate risk [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	$ 17,552,955	$ 592,205	$ 30,243,887
Cash flow interest rate risk [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets	39,880,736	1,345,504	29,977,709
Financial liabilities	$ 42,270,321	$ 1,426,124	$ 65,800,323

Financial Instruments - Summ195

Financial Instruments - Summary of Maturity Analysis for Non-derivative Financial Liabilities (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Less than 1 month [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	$ 45,860,103	$ 1,547,237	$ 39,001,592
1 to 3 months [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	30,067,396	1,014,420	26,805,023
3 months to 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	11,177,095	377,095	21,545,236
1-5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	39,101,387	1,319,210	73,099,796
More than 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	7,538,905	254,349	3,981,889
Non interest bearing [member] | Less than 1 month [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	30,695,797	1,035,621	23,907,221
Non interest bearing [member] | 1 to 3 months [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	18,387,296	620,354	20,553,395
Non interest bearing [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	4,549,468	153,491	4,360,322
Non interest bearing [member] | 1-5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	2,807	95	42,285
Non interest bearing [member] | More than 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	176,199	5,945	190,941
Floating interest rate [member] | Less than 1 month [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	6,641,541	224,073	9,733,727
Floating interest rate [member] | 1 to 3 months [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	4,153,830	140,143	5,232,407
Floating interest rate [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	5,101,178	172,104	6,634,931
Floating interest rate [member] | 1-5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	27,196,245	917,552	44,504,416
Floating interest rate [member] | More than 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	900,310	30,375	1,728,448
Fixed interest rate [member] | Less than 1 month [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	8,522,765	287,543	5,360,644
Fixed interest rate [member] | 1 to 3 months [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	7,526,270	253,923	1,019,221
Fixed interest rate [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	1,526,449	51,500	10,549,983
Fixed interest rate [member] | 1-5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	11,902,335	401,563	28,553,095
Fixed interest rate [member] | More than 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Non-derivative financial liabilities undiscounted amounts	$ 6,462,396	$ 218,029	$ 2,062,500

Financial Instruments - Summ196

Financial Instruments - Summary of Maturity Analysis for Derivative Financial Instruments (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	$ (40,897)	$ (1,379)	$ (205,559)
1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(164,400)	(5,547)	(144,919)
3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	227,325	7,669	655,299
Forward exchange contracts [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Net settled	(8,820)	(298)	22,680
Gross settled	32,148	1,085	(111,528)
Forward exchange contracts [member] | 1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Net settled			13,320
Gross settled	30,458	1,027	(3,687)
Forward exchange contracts [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	3,499	118
Forward exchange contracts [member] | Inflows [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	3,711,302	125,213	5,134,196
Forward exchange contracts [member] | Inflows [member] | 1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	2,169,093	73,181	912,213
Forward exchange contracts [member] | Inflows [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	390,379	13,171
Forward exchange contracts [member] | Outflows [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(3,679,154)	(124,128)	(5,245,724)
Forward exchange contracts [member] | Outflows [member] | 1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(2,138,635)	(72,154)	(915,900)
Forward exchange contracts [member] | Outflows [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(386,880)	(13,154)
Foreign currency option contracts [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Net settled			(344)
Swap contracts [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(73,045)	(2,464)	(94,031)
Swap contracts [member] | 1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(194,858)	(6,574)	(141,232)
Swap contracts [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	223,826	7,551	655,299
Swap contracts [member] | Inflows [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	12,116,531	408,790	5,345,159
Swap contracts [member] | Inflows [member] | 1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	14,434,880	487,007	17,399,695
Swap contracts [member] | Inflows [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	36,676,224	1,237,389	43,537,500
Swap contracts [member] | Outflows [member] | Less than 1 month [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(12,189,576)	(411,254)	(5,439,190)
Swap contracts [member] | Outflows [member] | 1 to 3 months [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	(14,629,738)	(493,581)	(17,540,927)
Swap contracts [member] | Outflows [member] | 3 months to 1 year [member]
Disclosure of maturity analysis for derivative financial liabilities [line items]
Gross settled	$ (36,452,898)	$ (1,229,838)	$ (42,882,201)

Financial Instruments - Reconci

Financial Instruments - Reconciliation of Liabilities Arising From Financing Activities (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	$ 111,070,988	$ 3,747,334
Financing cash flows	(19,636,346)	(662,494)
Non-cash changes
Amortization of issuance cost	325,253	10,973
Converted to ordinary shares in current period	(11,650,369)	(393,062)
Effects of exchange rate changes	(3,597,647)	(121,379)
Ending balance	76,511,879	2,581,372
Short-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	20,955,522	707,001
Financing cash flows	(2,038,993)	(68,792)
Non-cash changes
Effects of exchange rate changes	(954,058)	(32,188)
Ending balance	17,962,471	606,021
Bonds payable [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	36,999,903	1,248,310
Financing cash flows	(1,123,972)	(37,920)
Non-cash changes
Amortization of issuance cost	319,463	10,778
Converted to ordinary shares in current period	(11,650,369)	(393,062)
Effects of exchange rate changes	(1,402,245)	(47,310)
Ending balance	23,142,780	780,796
Long-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	53,115,563	1,792,023
Financing cash flows	(16,473,381)	(555,782)
Non-cash changes
Amortization of issuance cost	5,790	195
Effects of exchange rate changes	(1,241,344)	(41,881)
Ending balance	$ 35,406,628	$ 1,194,555

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) shares in Thousands, $ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 29, 2016TWD ($)shares	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)
Patents and Technology License [member]
Disclosure of transactions between related parties [line items]
Amounts payable		$ 93,000		$ 161,250				$ 3,138
USI Enterprise Limited [member]
Disclosure of transactions between related parties [line items]
Repurchase of outstanding ordinary shares | shares	1,801
Value of ordinary shares purchased	$ 1,130,650
Deca Technologies Inc. [member] | Patents and Technology License [member]
Disclosure of transactions between related parties [line items]
Intangible assets acquired				403,543
ASE Cultural and Educational Foundation [member] | Environmental charity [member]
Disclosure of transactions between related parties [line items]
Amount contributed related party transactions		$ 100,000	$ 3,374	100,000	$ 3,374	$ 100,000	$ 3,374
Associates [member]
Disclosure of transactions between related parties [line items]
Total consideration settled				875,000		$ 504,600
Associates [member] | Employee dormitory [member]
Disclosure of transactions between related parties [line items]
Amounts payable				$ 228,500

Related Party Transactions - Su

Related Party Transactions - Summary of Compensation to Key Management Personnel (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of transactions between related parties [abstract]
Short-term employee benefits	$ 860,631	$ 29,036	$ 790,460	$ 812,002
Post-employment benefits	2,858	97	4,790	3,944
Share-based payments			11,547	17,937
Total	$ 863,489	$ 29,133	$ 806,797	$ 833,883

Assets Pledged as Collateral200

Assets Pledged as Collateral or for Security - Summary of Assets Pledged as Collateral or for Security (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)
Assets Pledged As Collateral or For Security [Abstract]
Inventories related to real estate business	$ 4,822,043	$ 162,687	$ 16,813,023
Investment properties	8,119,436	273,935
Land use rights (recorded as long-term prepayment for lease)	6,813,751	229,884
Other financial assets (including current and non-current)	66,726	2,251	220,228
Total	$ 18,853,902	$ 636,097	$ 17,033,251

Significant Contingent Liabi201

Significant Contingent Liabilities and Unrecognized Commitments - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2013TWD ($)	Jan. 31, 2018TWD ($)	Jan. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Disclosure of contingent liabilities [line items]
Unused letters of credit	$ 20,000		$ 97,000				$ 675
Committed to purchase property, plant and equipment	7,019,377		6,630,957				$ 236,821
Prepayment of property, plant and equipment	294,194	$ 9,926	668,509
Construction contract related to real estate business	$ 1,548,806	$ 52,254	$ 1,574,822
Subsequent Event [Member]
Disclosure of contingent liabilities [line items]
Contribution to be made for environmental protection					$ 100,000	$ 3,374
Taiwan [member]
Disclosure of contingent liabilities [line items]
Contractual period for environmental protection				30 years
Contribution to be made for environmental protection				$ 3,000,000

Significant Assets and Liabi202

Significant Assets and Liabilities Denominated in Foreign Currencies - Summary of Significant Assets and Liabilities Denominated in Foreign Currencies (Detail) ¥ in Thousands, ¥ in Thousands, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015	Dec. 31, 2017USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2017JPY (¥)	Dec. 31, 2016USD ($)	Dec. 31, 2016CNY (¥)	Dec. 31, 2016JPY (¥)
US Dollar [member] | US dollar equals to New Taiwan dollar [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets	$ 91,223,195	$ 100,186,466		$ 3,065,296			$ 3,106,557
Financial liabilities	$ 86,393,137	$ 97,178,536		2,902,995			3,013,288
Exchange Rate	US$1=NT$29.76	US$1=NT$32.25	US$1=NT$32.825
Exchange Rate	US$1=NT$29.76	US$1=NT$32.25	US$1=NT$32.825
US Dollar [member] | US dollar equals to Chinese yuan [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets				1,193,369	¥ 35,514,653		1,020,769	¥ 32,919,814
Financial liabilities				1,007,629	¥ 29,987,042		891,487	¥ 28,750,462
Exchange Rate	US$1=CNY6.5342	US$1=CNY6.9370
Exchange Rate	US$1=CNY6.5342	US$1=CNY6.9370
Japanese Yen [Member] | Japanese yen equals to New Taiwan dollar [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets	$ 1,322,436	$ 1,371,471				¥ 5,005,435			¥ 4,976,309
Financial liabilities	$ 1,430,822	$ 1,621,001				5,415,677			5,881,716
Exchange Rate	JPY1=NT$0.2642	JPY1=NT$0.2756
Exchange Rate	JPY1=NT$0.2642	JPY1=NT$0.2756
Japanese Yen [Member] | Japanese yen equals to US dollar [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets				2,143,530		8,113,284	2,556,951		9,277,760
Financial liabilities				$ 2,271,811		¥ 8,598,832	$ 2,630,259		¥ 9,543,756
Exchange Rate	JPY1=US$0.0089	JPY1=US$0.0085
Exchange Rate	JPY1=US$0.0089	JPY1=US$0.0085

Significant Assets and Liabi203

Significant Assets and Liabilities Denominated in Foreign Currencies - Summary of Realized and Unrealized Foreign Exchange Gain (Loss) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about financial instruments [line items]
Net Foreign Exchange Gain (Loss)	$ 3,547,811	$ 119,697	$ 1,921,695	$ (830,073)
New Taiwan Dollar [member]
Disclosure of detailed information about financial instruments [line items]
Net Foreign Exchange Gain (Loss)	$ 4,130,243	$ 139,347	$ 1,494,044	$ (695,510)
US Dollar [member] | US dollar equals to New Taiwan dollar [member]
Disclosure of detailed information about financial instruments [line items]
Exchange Rate	US$1=NT$29.76	US$1=NT$29.76	US$1=NT$32.25	US$1=NT$32.825
Net Foreign Exchange Gain (Loss)	$ (244,802)	$ (8,259)	$ 203,258	$ 136,795
Chinese Yuan [member] | Chinese Yuan equals to New Taiwan dollar [member]
Disclosure of detailed information about financial instruments [line items]
Exchange Rate	CNY1=NT$4.5545	CNY1=NT$4.5545	CNY1=NT$4.649	CNY1=NT$5.0550
Net Foreign Exchange Gain (Loss)	$ (337,630)	$ (11,391)	$ 224,393	$ (271,358)

Others - Additional Information

Others - Additional Information (Detail) - TWD ($) $ / shares in Units, $ in Thousands	Dec. 20, 2013	Dec. 31, 2017
Disclosure Detailed Information About Others [Line Items]
Administrative fine imposed	$ 102,014
Estimated cash consideration description		The estimated cash consideration paid per SPIL's ordinary share shall not be subject to adjustment if the aggregate amount of the cash dividends distributed by SPIL in 2017 is less than 85% of SPIL's net profit for the year ended December 31, 2016.
ASE Holding [member]
Disclosure Detailed Information About Others [Line Items]
Number of ordinary shares exchanged from ASE Holding		0.5
Siliconware Precision Industries Co., Ltd. [member]
Disclosure Detailed Information About Others [Line Items]
Cash price per ordinary share		$ 55
Cash price per ordinary share adjusted		$ 51.2

Operating Segments Informati205

Operating Segments Information - Summary of Segment Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2017USD ($)
Disclosure of operating segments [line items]
OPERATING REVENUES	$ 290,441,208	$ 9,798,961	$ 274,884,107	$ 283,302,536
Interest income	306,871	10,353	230,067	242,084
Interest expense	(1,774,886)	(59,882)	(2,217,537)	(2,268,786)
Depreciation and amortization	(29,205,184)	(985,331)	(29,470,437)	(29,518,664)
Share of the profit or loss of associates and joint ventures	525,782	17,739	1,503,910	126,265
Impairment loss	(764,881)	(25,806)	(980,117)	(258,129)
Segment profit before income tax	31,020,663	1,046,581	27,968,705	25,011,788
Expenditures for segment assets	23,677,682	798,842	27,680,862	28,280,821
Investments accounted for using the equity method	48,753,751		49,824,690	37,122,244	$ 1,644,863
Segment assets	363,922,272		357,930,576	364,986,892	12,278,079
Packaging segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	126,225,119	4,258,607	125,282,829	116,607,314
Interest income	43,744	1,476	32,499	53,235
Interest expense	(1,969,562)	(66,450)	(1,727,127)	(1,520,118)
Depreciation and amortization	(19,105,457)	(644,584)	(18,706,891)	(18,946,460)
Share of the profit or loss of associates and joint ventures	568,291	19,173	1,513,394	126,265
Impairment loss	(218,214)	(7,362)	(974,095)	(139,397)
Segment profit before income tax	12,065,304	407,061	13,921,640	15,479,868
Expenditures for segment assets	17,769,612	599,515	17,561,135	19,691,068
Investments accounted for using the equity method	48,566,333		49,597,195	37,122,244	1,638,540
Segment assets	195,503,889		200,604,111	193,323,304	6,595,947
Testing segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	26,157,277	882,499	27,031,750	25,191,916
Interest income	48,532	1,637	41,405	12,536
Interest expense	(11,920)	(402)	(5,980)	(5,821)
Depreciation and amortization	(6,476,743)	(218,514)	(6,566,936)	(6,516,912)
Share of the profit or loss of associates and joint ventures	(42,509)	(1,434)	(9,484)
Impairment loss	(72,798)	(2,456)	(4,136)
Segment profit before income tax	6,904,067	232,931	7,226,531	6,354,140
Expenditures for segment assets	4,507,097	152,061	8,247,003	4,754,481
Investments accounted for using the equity method	187,418		227,495		6,323
Segment assets	43,383,691		42,962,643	42,652,569	1,463,687
EMS segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	133,948,016	4,519,164	115,395,130	138,242,100
Interest income	269,640	9,097	130,659	149,385
Interest expense	0	0	(44,433)	(147,792)
Depreciation and amortization	(2,133,253)	(71,972)	(2,759,298)	(2,738,722)
Impairment loss			(1,886)	(102,389)
Segment profit before income tax	6,883,327	232,231	4,626,263	2,874,944
Expenditures for segment assets	850,235	28,685	906,042	2,917,939
Segment assets	81,588,691		73,915,639	79,997,341	2,752,655
Estate Segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	412,863	13,929	3,909,580	1,340
Interest income	30,441	1,027	29,131	54,876
Interest expense	(62,714)	(2,116)
Depreciation and amortization	(180,792)	(6,100)	(55,271)	(24,074)
Segment profit before income tax	5,120,301	172,750	1,546,326	(172,521)
Expenditures for segment assets	169,559	5,721	114,462	143,436
Segment assets	33,080,694		28,468,242	30,000,273	1,116,083
All other segments [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	3,697,933	124,762	3,264,818	3,259,866
Interest income	183,824	6,202	8,166	13,445
Interest expense	0	0	(451,790)	(636,448)
Depreciation and amortization	(1,308,939)	(44,160)	(1,382,041)	(1,292,496)
Impairment loss	(473,869)	(15,988)		(16,343)
Segment profit before income tax	47,664	1,608	647,945	475,357
Expenditures for segment assets	381,179	12,860	852,220	773,897
Segment assets	10,365,307		11,979,941	19,013,405	$ 349,707
Adjustments and Eliminations [member]
Disclosure of operating segments [line items]
Interest income	(269,310)	(9,086)	(11,793)	(41,393)
Interest expense	269,310	9,086	11,793	41,393
Inter-segment revenues [member] | Packaging segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	4,911,026	165,689	4,929,897	9,454,671
Inter-segment revenues [member] | Testing segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	184,707	6,232	243,980	191,608
Inter-segment revenues [member] | EMS segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	47,119,404	1,589,723	47,721,424	58,451,996
Inter-segment revenues [member] | Estate Segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	23,943	808
Inter-segment revenues [member] | All other segments [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	8,359,697	282,041	9,186,359	7,659,282
Inter-segment revenues [member] | Adjustments and Eliminations [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	(60,598,777)	(2,044,493)	(62,081,660)	(75,757,557)
Operating segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	351,039,985	11,843,454	336,965,767	359,060,093
Operating segment [member] | Packaging segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	131,136,145	4,424,296	130,212,726	126,061,985
Operating segment [member] | Testing segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	26,341,984	888,731	27,275,730	25,383,524
Operating segment [member] | EMS segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	181,067,420	6,108,887	163,116,554	196,694,096
Operating segment [member] | Estate Segment [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	436,806	14,737	3,909,580	1,340
Operating segment [member] | All other segments [member]
Disclosure of operating segments [line items]
OPERATING REVENUES	$ 12,057,630	$ 406,803	$ 12,451,177	$ 10,919,148

Operating Segments Informati206

Operating Segments Information - Summary of Revenue from Major Products and Services (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of products and services [line items]
OPERATING REVENUES	$ 290,441,208	$ 9,798,961	$ 274,884,107	$ 283,302,536
Packaging service [member]
Disclosure of products and services [line items]
OPERATING REVENUES	126,225,119	4,258,607	125,282,829	116,607,314
Testing service [member]
Disclosure of products and services [line items]
OPERATING REVENUES	26,157,277	882,499	27,031,750	25,191,916
Electronic components manufacturing service [member]
Disclosure of products and services [line items]
OPERATING REVENUES	133,948,016	4,519,164	115,395,130	138,242,100
Other products and services [member]
Disclosure of products and services [line items]
OPERATING REVENUES	$ 4,110,796	$ 138,691	$ 7,174,398	$ 3,261,206

Operating Segments Informati207

Operating Segments Information - Summary of Geographical Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2017USD ($)
Disclosure of geographical areas [line items]
OPERATING REVENUES	$ 290,441,208	$ 9,798,961	$ 274,884,107	$ 283,302,536
Noncurrent assets, excluding financial instruments, post-employment benefit assets and deferred tax assets	163,752,501		158,415,041		$ 5,524,714
United States [Member]
Disclosure of geographical areas [line items]
OPERATING REVENUES	196,462,345	6,628,284	180,745,837	205,730,670
Taiwan [member]
Disclosure of geographical areas [line items]
OPERATING REVENUES	35,413,647	1,194,792	38,868,679	32,631,149
Noncurrent assets, excluding financial instruments, post-employment benefit assets and deferred tax assets	93,350,839		97,337,094		3,149,489
Asia [Member]
Disclosure of geographical areas [line items]
OPERATING REVENUES	30,201,332	1,018,938	29,896,304	22,885,128
Europe [Member]
Disclosure of geographical areas [line items]
OPERATING REVENUES	26,445,240	892,215	23,275,732	20,577,069
Other geographical areas [member]
Disclosure of geographical areas [line items]
OPERATING REVENUES	1,918,644	$ 64,732	2,097,555	$ 1,478,520
Noncurrent assets, excluding financial instruments, post-employment benefit assets and deferred tax assets	25,025,498		26,935,370		844,315
China [member]
Disclosure of geographical areas [line items]
Noncurrent assets, excluding financial instruments, post-employment benefit assets and deferred tax assets	$ 45,376,164		$ 34,142,577		$ 1,530,910

Operating Segments Informati208

Operating Segments Information - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of operating segments [line items]
Operating revenue	$ 290,441,208	$ 9,798,961	$ 274,884,107	$ 283,302,536
Packaging and EMS segments [member] | Customer One [member]
Disclosure of operating segments [line items]
Operating revenue	$ 83,873,393	$ 2,829,737	$ 66,554,659	$ 88,311,697