Siliconware Precision Industries (SPILA) 20-F 27 Mar 18 2017 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Dec. 31, 2017shares
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	SPIL
Entity Registrant Name	SILICONWARE PRECISION INDUSTRIES CO LTD
Entity Central Index Key	1,111,759
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	3,116,361,139

Consolidated Balance Sheets

Consolidated Balance Sheets $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Current Assets
Cash and cash equivalents	$ 824,699	$ 24,444,083	$ 24,476,270
Available-for-sale financial assets, current	0	0	178,176
Notes receivable, net	536	15,879	23,591
Accounts receivable, net	568,863	16,861,111	17,354,883
Other receivables	16,602	492,081	581,630
Inventories	206,602	6,123,682	6,498,832
Non-current assets held for sale	0	0	387,503
Other current assets - other	38,093	1,129,076	950,410
Current Assets	1,655,395	49,065,912	50,451,295
Non-current Assets
Available-for-sale financial assets, non-current	139,515	4,135,207	3,615,658
Investments accounted for using the equity method	97,761	2,897,644	2,401,531
Property, plant and equipment	2,105,198	62,398,065	65,380,409
Intangible assets	4,024	119,268	175,862
Deferred income tax assets	20,740	614,733	752,712
Other non-current assets - other	53,815	1,595,087	949,840
Non-current Assets	2,421,053	71,760,004	73,276,012
TOTAL ASSETS	4,076,448	120,825,916	123,727,307
Current Liabilities
Short-term loans	115,466	3,422,400	2,741,250
Financial liability at fair value through profit or loss, current	27,316	809,640	773,908
Accounts payable	251,585	7,456,974	8,194,647
Other payables	340,172	10,082,704	11,896,517
Current income tax liabilities	25,779	764,082	653,222
Current portion of convertible bonds	0	0	12,712,651
Current portion of long-term loans	107,062	3,173,333	3,500,747
Other current liabilities - other	16,379	485,482	615,497
Current Liabilities	883,759	26,194,615	41,088,439
Non-current Liabilities
Convertible bonds	405,372	12,015,229	0
Long-term loans	427,350	12,666,667	14,840,000
Deferred income tax liabilities	16,180	479,583	264,360
Other non-current liabilities	69,224	2,051,787	2,414,050
Non-current Liabilities	918,126	27,213,266	17,518,410
Total Liabilities	1,801,885	53,407,881	58,606,849
Shareholders' Equity
Capital stock	1,051,404	31,163,611	31,163,611
Capital reserve	426,539	12,642,615	12,641,997
Retained earnings
Legal reserve	399,370	11,837,317	10,844,001
Unappropriated earnings	339,475	10,062,036	9,337,450
Accumulated other comprehensive income	57,775	1,712,456	1,133,399
Total Shareholders' Equity	2,274,563	67,418,035	65,120,458
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 4,076,448	$ 120,825,916	$ 123,727,307

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2017TWD ($)$ / shares	Dec. 31, 2016TWD ($)$ / shares	Dec. 31, 2015TWD ($)$ / shares
Profit or loss [abstract]
Operating Revenues	$ 2,818,974	$ 83,554,385	$ 85,111,913	$ 82,839,922
Operating Costs	(2,251,697)	(66,740,290)	(65,762,191)	(61,230,622)
Gross Profit	567,277	16,814,095	19,349,722	21,609,300
Operating Expenses
Selling expenses	(34,845)	(1,032,799)	(1,024,689)	(944,499)
General and administrative expenses	(110,126)	(3,264,130)	(3,495,613)	(3,671,161)
Research and development expenses	(129,622)	(3,841,996)	(4,043,290)	(3,739,109)
Operating Expenses	(274,593)	(8,138,925)	(8,563,592)	(8,354,769)
Other Income and Expenses	4,286	127,046	(117,006)	(255,817)
Operating Profit	296,970	8,802,216	10,669,124	12,998,714
Non-operating Income and Expenses
Interest income	5,070	150,260	148,484	155,524
Other gains and losses	1,349	39,976	(104,365)	57,553
Finance costs	(20,034)	(593,821)	(562,337)	(565,450)
Impairment loss of available-for-sale equity securities	0	0	0	(1,856,442)
Share of (losses) gains of associates and joint ventures accounted for using equity method	2,498	74,035	3,221	(183,708)
Dividends income	6,910	204,810	277,798	347,408
Gains on disposal of investments	1,868	55,369	217,199	127,291
(Losses)/ Gains on financial liabilities at fair value through profit or loss	(1,206)	(35,732)	1,025,012	(703,368)
Non-operating Income and Expenses	(3,545)	(105,103)	1,005,012	(2,621,192)
Income before Income Tax	293,425	8,697,113	11,674,136	10,377,522
Income Tax Expense	(51,470)	(1,525,579)	(1,867,199)	(1,366,059)
Net Income	241,955	7,171,534	9,806,937	9,011,463
Items that may be subsequently reclassified to profit or loss
Exchange difference on translation of foreign financial statements	(7,636)	(226,323)	(908,801)	(227,905)
Unrealized gain (loss) on available-for-sale financial assets	15,694	465,175	(1,469,105)	(549,845)
Share of other comprehensive income (loss) of associates and joint ventures	14,135	418,944	(121,957)	0
Income tax relating to items that may be reclassified to profit or loss	(2,955)	(87,576)	273,910	20,244
Items that may be subsequently reclassified to profit or loss	19,238	570,220	(2,225,953)	(757,506)
Items that will not be reclassified to profit or loss
Remeasurements of post-employment benefit obligations	359	10,647	(177,806)	(179,842)
Income tax relating to items that will not be reclassified to profit or loss	(61)	(1,810)	30,227	30,572
Items that will not be reclassified to profit or loss	298	8,837	(147,579)	(149,270)
Other Comprehensive Income (Loss) for the year, net of tax	19,536	579,057	(2,373,532)	(906,776)
Total Comprehensive Income for the year	261,491	7,750,591	7,433,405	8,104,687
Net Income Attributable to:
Owners of the parent	241,955	7,171,534	9,806,937	9,011,463
Total Comprehensive Income Attributable to:
Owners of the parent	$ 261,491	$ 7,750,591	$ 7,433,405	$ 8,104,687
Earnings Per Share (in New Taiwan dollars)
Basic | (per share)	$ 0.08	$ 2.30	$ 3.15	$ 2.89
Diluted | (per share)	$ 0.07	$ 1.94	$ 2.65	$ 2.86

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity $ in Thousands, $ in Thousands	USD ($)	TWD ($)	Capital stock [member]USD ($)	Capital stock [member]TWD ($)	Capital reserve [member]USD ($)	Capital reserve [member]TWD ($)	Retained earnings [member]Retained earnings, legal reserve [member]USD ($)	Retained earnings [member]Retained earnings, legal reserve [member]TWD ($)	Retained earnings [member]Retained earnings, unappropriated earnings [member]USD ($)	Retained earnings [member]Retained earnings, unappropriated earnings [member]TWD ($)	Other Comprehensive Income (Loss) [Member]Other comprehensive income, unrealized gain on valuation of available-for-sale financial assets [member]USD ($)	Other Comprehensive Income (Loss) [Member]Other comprehensive income, unrealized gain on valuation of available-for-sale financial assets [member]TWD ($)	Other Comprehensive Income (Loss) [Member]Other comprehensive income, exchange difference on translation of foreign financial statements [member]USD ($)	Other Comprehensive Income (Loss) [Member]Other comprehensive income, exchange difference on translation of foreign financial statements [member]TWD ($)	Other Comprehensive Income (Loss) [Member]Other comprehensive income, remeasurements of post-employment benefit obligations [member]USD ($)	Other Comprehensive Income (Loss) [Member]Other comprehensive income, remeasurements of post-employment benefit obligations [member]TWD ($)
Beginning balance at Dec. 31, 2014		$ 70,773,742		$ 31,163,611		$ 15,758,479		$ 8,797,005		$ 10,640,940		$ 3,670,115		$ 720,253		$ 23,339
Appropriation of earnings for prior years:
Legal reserve		0		0		0		1,170,770		(1,170,770)		0		0		0
Cash dividends		(9,349,083)		0		0		0		(9,349,083)		0		0		0
Subsidiary's share issue transaction costs		(121)		0		(121)		0		0		0		0		0
Net income		9,011,463		0		0		0		9,011,463		0		0		0
Other comprehensive income (loss)		(906,776)		0		0		0		0		(530,235)		(227,271)		(149,270)
Total comprehensive income		8,104,687		0		0		0		9,011,463		(530,235)		(227,271)		(149,270)
Ending balance at Dec. 31, 2015		69,529,225		31,163,611		15,758,358		9,967,775		9,132,550		3,139,880		492,982		(125,931)
Appropriation of earnings for prior years:
Legal reserve		0		0		0		876,226		(876,226)		0		0		0
Cash dividends		(8,725,811)		0		0		0		(8,725,811)		0		0		0
Cash distribution from capital reserve		(3,116,361)		0		(3,116,361)		0		0		0		0		0
Net income		9,806,937		0		0		0		9,806,937		0		0		0
Other comprehensive income (loss)		(2,373,532)		0		0		0		0		(1,317,722)		(908,231)		(147,579)
Total comprehensive income		7,433,405		0		0		0		9,806,937		(1,317,722)		(908,231)		(147,579)
Ending balance at Dec. 31, 2016		65,120,458		31,163,611		12,641,997		10,844,001		9,337,450		1,822,158		(415,249)		(273,510)
Appropriation of earnings for prior years:
Legal reserve		0		0		0		993,316		(993,316)		0		0		0
Cash dividends		(5,453,632)		0		0		0		(5,453,632)		0		0		0
Changes in other capital reserve		618		0		618		0		0		0		0		0
Net income	$ 241,955	7,171,534		0		0		0		7,171,534		0		0		0
Other comprehensive income (loss)	19,536	579,057		0		0		0		0		796,737		(226,517)		8,837
Total comprehensive income	261,491	7,750,591		0		0		0		7,171,534		796,737		(226,517)		8,837
Ending balance at Dec. 31, 2017	$ 2,274,563	$ 67,418,035	$ 1,051,404	$ 31,163,611	$ 426,539	$ 12,642,615	$ 399,370	$ 11,837,317	$ 339,475	$ 10,062,036	$ 88,357	$ 2,618,895	$ (21,652)	$ (641,766)	$ (8,930)	$ (264,673)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Cash flows from operating activities
Consolidated income before tax	$ 293,425	$ 8,697,113	$ 11,674,136	$ 10,377,522
Adjustments to reconcile consolidated income before tax to net cash provided by operating activities:
Depreciation	486,369	14,415,980	12,905,830	12,903,772
Amortization	7,062	209,319	385,360	610,213
Provision for bad debt expense	402	11,911	0	0
Losses/ (Gains) on financial liabilities at fair value through profit or loss	1,206	35,732	(1,025,012)	703,368
Interest expense	20,011	593,115	561,613	564,540
Interest income	(5,070)	(150,260)	(148,484)	(155,524)
Dividend income	(6,910)	(204,810)	(277,798)	(347,408)
Share of losses (gains) of associates and joint ventures accounted for using the equity method	(2,498)	(74,035)	(3,221)	183,708
Impairment loss of available-for-sale financial assets	0	0	0	1,856,442
Gains on reversal of impairment loss of non-financial assets	0	0	0	(134,992)
Gains on disposal of property, plant and equipment	(5,080)	(150,579)	(32,615)	(31,293)
Gains on disposal of non-current assets held for sale	(655)	(19,402)	0	0
Gain on disposal of investment	(1,868)	(55,369)	(217,199)	(127,291)
Impairment loss on property, plant and equipment	2,977	88,231	91,247	64,996
Foreign currency exchange losses (gains) on convertible bonds payable	(33,303)	(987,093)	(221,082)	451,156
Foreign currency exchange gains on long-term loans	(9,830)	(291,375)	(105,712)	(28,790)
Premium from merger of available-for-sale financial assets	0	0	(51,923)	0
Changes in assets and liabilities related to the operation
Notes receivable	249	7,389	(13,195)	(1,325)
Accounts receivable	14,900	441,656	(1,794,834)	2,658,604
Other receivables	2,468	73,152	1,301	295,714
Inventories	12,205	361,748	(1,321,346)	(132,271)
Other current assets-other	(4,964)	(147,132)	(2,590)	(384,471)
Other non-current assets-other	(21,676)	(642,483)	23,405	(95,494)
Accounts payable	(24,007)	(711,571)	1,359,898	(321,445)
Other payables	(20,900)	(619,470)	392,429	410,903
Other current liabilities	(5,336)	(158,151)	(23,780)	30,821
Other non-current liabilities	(377)	(11,185)	58,033	(6,277)
Cash provided by operations	698,800	20,712,431	22,214,461	29,345,178
Interest received	5,390	159,776	150,419	162,742
Dividend received	6,581	195,072	277,798	347,408
Interest paid	(10,158)	(301,086)	(247,829)	(257,415)
Income tax paid	(46,245)	(1,370,710)	(1,550,297)	(2,813,747)
Net cash provided by operating activities	654,368	19,395,483	20,844,552	26,784,166
Cash flows from investing activities
Proceeds from disposal of available-for-sale financial assets	0	0	1,454,403	0
Proceeds from disposal of investments accounted for using the equity method	0	0	0	29,645
Acquisition of investments accounted for using the equity method	0	0	0	(2,400,000)
Proceeds from liquidation of available-for-sale financial assets	5,967	176,855	0	0
Proceeds from disposal of non-current assets held for sale	13,892	411,745	0	0
Acquisition of property, plant, and equipment	(436,324)	(12,932,655)	(15,295,121)	(13,855,431)
Proceeds from disposal of property, plant, and equipment	7,110	210,742	167,021	111,274
Increase in refundable deposits	(24,091)	(714,040)	(561,010)	(162,225)
Decrease in refundable deposits	18,441	546,603	237,007	65,326
Acquisition of intangible assets	(986)	(29,237)	(71,011)	(112,692)
(Increase) decrease in pledged deposits	(1,171)	(34,700)	27,000	(44,800)
Increase in other non-current assets	0	0	0	(218,536)
Net cash used in investing activities	(417,162)	(12,364,687)	(14,041,711)	(16,587,439)
Cash flows from financing activities
Increase in short-term loans	76,423	2,265,169	0	0
Decrease in short-term loans	(45,651)	(1,353,089)	0	0
Proceeds from long-term loans	33,738	1,000,000	9,000,000	2,500,000
Repayment of long-term loans	(115,152)	(3,413,112)	(4,228,721)	(8,235,833)
Payment for issuance of subsidiary's stock	0	0	0	(121)
Increase in deposit-in	2,454	72,744	35,889	65,112
Decrease in deposit-in	(1,720)	(50,995)	(126,329)	(76,366)
Payment for cash dividends and cash distribution from capital reserve	(183,996)	(5,453,632)	(11,842,172)	(9,349,083)
Net cash used in financing activities	(233,904)	(6,932,915)	(7,161,333)	(15,096,291)
Effect on foreign currency exchange	(4,388)	(130,068)	(356,612)	(63,775)
Net decrease in cash and cash equivalents	(1,086)	(32,187)	(715,104)	(4,963,339)
Cash and cash equivalents at the beginning of the year	825,785	24,476,270	25,191,374	30,154,713
Cash and cash equivalents at the end of the year	$ 824,699	$ 24,444,083	$ 24,476,270	$ 25,191,374

History and Organization

History and Organization	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
History and Organization	1. History and Organization Siliconware Precision Industries Co., Ltd. (the “Company”) was incorporated as a company limited by shares under the Company Law of the Republic of China (R.O.C.) in May 1984, and has been listed on the Taiwan Stock Exchange since April 1993, and on the NASDAQ National Market under the trading symbol of SPIL since June 2000. The Company is mainly engaged in the assembly, testing and turnkey services of integrated circuits. The address of the registered office is No. 123, Sec. 3, Da Fong Rd., Tantzu, Taichung 427, Taiwan, R.O.C.

The Date of Authorization for I

The Date of Authorization for Issuance of the Consolidated Financial Statements and Procedures for Authorization	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
The Date of Authorization for Issuance of the Consolidated Financial Statements and Procedures for Authorization	2. The Date of Authorization for Issuance of the Consolidated Financial Statements and Procedures for Authorization The consolidated financial statements have been authorized for issuance by the Audit Committee on March 22, 2018.

The Adoption of New and Amended

The Adoption of New and Amended Standards and Interpretations	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
The Adoption of New and Amended Standards and Interpretations	3. The Adoption of New and Amended Standards and Interpretations A. New Standards and Interpretations Not Yet Adopted New Standards, Amendments, and Content Effective IFRS 15, ‘Revenue from contracts with customers’ and amendments The standard deals with revenue recognition and establishes principles for reporting useful information to users of financial statements about the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. Revenue is recognised when a customer obtains control of a good or service and thus has the ability to direct the use and obtain the benefits from the good or service. The standard replaces IAS 18 ‘Revenue’ and IAS 11 ‘Construction contracts’ and related interpretations. The amendments to IFRS 15 clarify how to identify a performance obligation (the promise to transfer a good or a service to a customer) in a contract; determine whether a company is a principal (the provider of a good or service) or an agent (responsible for arranging for the good or service to be provided); and determine whether the revenue from granting a license should be recognized at a point in time or over time. In addition to the clarifications, the amendments include two additional reliefs to reduce cost and complexity for a company when it first applies the new Standard. The amendments introduce two new practical expedients to simplify transition. One expedient allows entities to use hindsight at the beginning of the earliest period presented or the date of initial application to account for contract modifications before that date. The second expedient allows entities applying the full retrospective method to elect not to restate contracts that are completed at the beginning of the earliest period presented. January 1, 2018 IFRS 9, ‘Financial instruments’ The complete version of IFRS 9 was issued in July 2014. It replaces the guidance in IAS 39 that relates to the classification and measurement of financial instruments. IFRS 9 retains but simplifies the mixed measurement model and establishes three primary measurement categories for financial assets, namely, amortised cost, fair value through other comprehensive income(loss) and fair value through profit and loss. The basis of classification depends on the entity’s business model and the contractual cash flow characteristics of the financial asset. Investments in equity instruments are required to be measured at fair value through profit or loss, with the irrevocable option at inception to present changes in fair value in other comprehensive not recycled to profit and loss. There is now a new expected credit losses model that replaces the incurred loss impairment model used in IAS 39. For financial liabilities, there were no changes to classification and measurement except for the recognition of changes in own credit risk in other comprehensive income, for liabilities designated at fair value through profit or loss. IFRS 9 relaxes the requirements for hedge effectiveness by replacing the bright line hedge effectiveness tests. It requires an economic relationship between the hedged item and hedging instrument and for the “hedged ratio” to be the same as the one management actually use for risk management purposes. Contemporaneous documentation is still required but is different to that currently prepared under IAS 39. January 1, 2018 IFRS 16, ‘Leases’ ‘Leases’ addresses the definition of a lease, recognition and measurement of leases and establishes principles for reporting useful information to users of financial statements about the leasing activities of both lessees and lessors. A key change arising from IFRS 16 is that most operating leases will be accounted for on balance sheet for lessees. The standard replaces IAS 17 ‘Leases’, and related interpretations. An entity shall apply IFRS 16 for annual periods beginning on or after January 1, 2019 and earlier application is permitted subject to the entity adopting IFRS 15 ‘Revenue from contracts with customers’ at the same time. January 1, 2019 The Group elects modified retrospective approach to 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. After adopting IFRS15, in the case of services provided according to the customer’s agreed specifications, if the customer simultaneously obtains and consumes the benefits provided by the performance of the Group, or when the customer controls the assets at the time the assets are created or strengthened, the Group will gradually recognize its revenue over time. Before adopting IFRS15, the Group recognized revenue at a point of time when the process agreed with the customer was completed. 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 on January 1, 2018. After adopting IFRS 9, the Group plans to adopt a simplified approach for accounts receivable and contract assets and measure the loss allowance at an amount equal to life time expected credit losses under credit loss model. Before adopting IFRS 9, the Group assessed at the end of each reporting period whether there is no objective evidence on impairment, and then collectively assessed impairment on receivables. The significant effects of adopting the new standards as of January 1, 2018 are summarized as below: Affected Items of Consolidated Balance Sheet As of Effect of As of Remark Financial assets at fair value through profit or loss, non-current $ — $ 4,135,207 $ 4,135,207 (A) Available-for-sale financial assets, non-current 4,135,207 (4,135,207 ) — (A) Contract assets - current — 1,766,801 1,766,801 (C)(a)(b) Accounts receivable, net 16,861,111 (909,849 ) 15,951,262 (B), (C)(a) Other receivables 492,081 (1,204 ) 490,877 (B) Inventories 6,123,682 (717,551 ) 5,406,131 (C)(b) Deferred income tax assets 614,733 1,805 616,538 (E) Total affected assets $ 28,226,814 $ 140,002 $ 28,366,816 Contract liabilities - current $ — $ 12,128 $ 12,128 (C)(c) Other current liabilities - other 485,482 (12,128 ) 473,354 (C)(c), (D) Deferred income tax liabilities 479,583 27,196 506,779 (E) Total affected liabilities 965,065 27,196 992,261 Unappropriated earnings 10,062,036 2,457,578 12,519,614 (A),(B),(C)(b),(E) Accumulated other comprehensive income 1,712,456 (2,344,772 ) (632,316 ) (A) Total affected equity 11,774,492 112,806 11,887,298 Total affected liabilities and equity $ 12,739,557 $ 140,002 $ 12,879,559 Explanation: (A) When adopting IFRS 9, the Group expects to reclassify available-for-sale financial assets of $4,135,207 to financial assets at fair value through profit or loss, and increase retained earnings and decrease accumulated other comprehensive income in the amounts of $2,344,772 and $2,344,772, respectively. (B) In line with the regulations of IFRS 9 on provision for impairment, accounts receivable and other receivables will be reduced by $8,370 and $1,204, respectively, and retained earnings will be decreased by $9,574. (C) Presentation of contract assets and contract liabilities When adopting IFRS 15, the Group expects to change the presentation of certain accounts in the balance sheet as follows: (a) Under IFRS 15, the services which have been rendered but not yet billed will be recognized as contract assets, but were previously presented as part of accounts receivable in the balance sheet. As of January 1, 2018, the balance of contract asset is $901,479. (b) Under IFRS 15, the services which have been processed before completion will be recognized as contract assets over time. As of January 1, 2018, the contract assets and retained earnings will be increased by $865,322 and $147,771, respectively, and the related work-in-process inventories to satisfy the performance obligation over time will be decreased by $717,551. (c) Under IFRS 15, the Group’s obligation to transfer services to a customer for which the Group has received consideration from customer are recognized as contract liabilities, but were previously presented as advance sales receipts in the balance sheet. As of January 1, 2018, the balance of contract liabilities will be $12,128. (D) Under IFRS 15, current provisions (shown as other liabilities - current are reclassified as refund liabilities (shown as other liabilities - current), but were previously presented as current provisions (shown as other liabilities - current) in the balance sheet. As of January 1, 2018, the balance is $316,391. (E) Recognition of deferred income tax assets and liabilities. When initially adopting IFRS 9 and IFRS 15, the Group will recognize deferred income tax assets and liabilities for the temporary differences resulted from the adjustments. Accordingly, deferred income tax assets and deferred income tax liabilities will be increased by $1,805 and $27,196 and retained earnings will be decreased by $25,391, respectively, on January 1, 2018. B. New Standards and Interpretations Adopted The Group has applied the following standards and amendments for the first time for their annual reporting period commencing January 1, 2017: • Disclosure Initiative - Amendments to IAS 7 • Recognition of Deferred Tax Assets for Unrealized Losses - Amendments to IAS 12 • Annual improvements to IFRSs 2014-2016 cycle - Amendments to IFRS 12 The adoption of these amendments did not have significant impact on the current period or any prior period and is not likely to affect future periods, and according with Disclosure Initiative - Amendment to IAS 7, which requires that the Group should provide more disclosures related to changes in liabilities arising from financing activities. The additional disclosure is disclosed in Note 29B.

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 (1) Basis of Preparation A. Compliance with IFRS The consolidated financial statements have been prepared in accordance with International Financial Reporting Standards and the interpretations of the IFRS interpretations committee (“IFRIC”). The accompanying consolidated financial statements are prepared in conformity with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). B. Historical cost convention The consolidated financial statements have been prepared on a historical cost basis, except for the following: • available-for-sale financial assets, financial assets and liabilities (including derivative instruments)—measured at fair value • defined benefit pension plans - net amount of pension fund assets less present value of defined benefit obligation measured at fair value. The preparation requires the use of certain critical accounting estimates and also requires management to exercise its judgement in the process of applying the accounting policies. The areas involving a higher degree of judgement or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are disclosed in Note 5. (2) Principles of Consolidation Pursuant to IFRS 10, “Consolidated financial statements”, subsidiaries are those entities controlled by the Company or its subsidiaries. The Company controls an entity when the Company is exposed to, or has right to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Company. They are deconsolidated from the date that control ceases. Inter-company transactions, balances and unrealized gains on transactions between group companies are eliminated. Unrealized losses are also eliminated. Accounting policies of subsidiaries have been changed where necessary to ensure consistency with the policies adopted by the Group. Consolidated subsidiaries: % of ownership held by the named Name of investor Name of subsidiaries Main operating activities 2016 2017 The Company SPIL (B.V.I.) Holding Limited Investment activities 100 % 100 % The Company Siliconware Investment Co., Ltd. Investment activities 100 % 100 % SPIL (B.V.I.) Holding Limited Siliconware USA, Inc. (SUI) Communications and relationship maintenance with companies headquartered in North America 100 % 100 % SPIL (B.V.I.) Holding Limited SPIL (Cayman) Holding Limited Investment activities 100 % 100 % SPIL (Cayman) Holding Limited Siliconware Technology (Suzhou) Limited Assembly and testing services 100 % 100 % SPIL (Cayman) Holding Limited Siliconware Electronics (Fujian) Co., Limited (1) Assembly and testing services — 100 % (1) Siliconware Electronics (Fujian) Co., Limited was established in July 2017 and mainly engaged in assembly and testing service for memory and logic devices with initial capital of US$45,000 thousands. (3) Segment Reporting Operating segments are reported in a manner consistent with the internal reporting provided to the chief operating decision maker. The chief operating decision maker assesses performance and allocates resources based on the economic environment. All of the Company’s segments have similar economic characteristics and meet the criteria of aggreggation. As a result, the Company discloses a single reporting segment by aggregating all the operating segments. (4) Foreign Currency Translation A. Convenience Translation into US Dollars The Group maintains its accounting records and prepares its financial statements in New Taiwan (“NT”) dollars. The United States (“US”) dollar amounts disclosed in the 2017 financial statements are presented solely for the convenience of the reader and were translated at the rate of NT$29.64 (in dollars) to US$1.00 (in dollars), which was the noon buying rate as certified for customs purposes by the Federal Reserve Bank of New York on December 29, 2017 as the last quoted rate at the balance sheet date. Such translation amounts are unaudited and should not be construed that the NT dollar amounts represent, or have been, or could be, converted into US dollars at that or any other rate. B. Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in New Taiwan Dollar (“NTD”), which is the presentation currency of the Group and the functional currency of the Company. C. Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions where items are re-measured. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies are recognized as other gains and losses in the statement of comprehensive income. D. Translation differences on non-monetary financial assets and liabilities such as equities held at fair value through profit or loss are recognized in profit or loss as part of the fair value gain or loss. Translation differences on non-monetary financial assets, such as equities classified as available-for-sale, are included in other comprehensive income. However, non-monetary assets and liabilities denominated in foreign currencies that are not measured at fair value are translated using the historical exchange rates at the dates of the initial transactions. E. The results and financial position of the Group entities that have a functional currency different from the presentation currency are translated into the presentation currency. Assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet, income and expenses for each statement of comprehensive income are translated at average exchange rates (unless this average is not a reasonable approximation of the cumulative effect of the rates prevailing on the transaction dates, in which case income and expenses are translated at the rate on the dates of the transactions), and all resulting exchange differences are recognized in other comprehensive income. Those differences would be recorded as gain or loss of disposal of investments in statement of comprehensive income if disposed. (5) Classification of Current and Noncurrent Assets / Liabilities A. Assets that meet one of the following criteria are classified as current assets; otherwise they are classified as noncurrent assets: (a) Assets arising from operating activities that are expected to be realized or consumed, or are intended to be sold within the normal operation cycle; (b) Assets held mainly for trading purposes; (c) Assets expected to be realized within twelve months from the balance sheet date; (d) Cash or cash equivalents, excluding restricted cash and cash equivalents and those that are to be exchanged or used to pay off liabilities more than twelve months after the balance sheet date. B. Liabilities that meet one of the following criteria are classified as current liabilities; otherwise they are classified as noncurrent liabilities: (a) Liabilities arising from operating activities that are expected to be paid off within the normal operating cycle; (b) Liabilities arising mainly from trading activities; (c) Liabilities that are to be paid off within twelve months from the balance sheet date; (d) Liabilities for which the repayment date cannot be extended unconditionally to more than twelve months after the balance sheet date. (6) Cash and Cash Equivalents Cash and cash equivalents include cash on hand, deposits held at call with banks, time deposits that meet operating short-term cash commitments and that are readily convertible to known amounts of cash and are subject to an insignificant risk of changes in value, and other short-term highly liquid investments. (7) Accounts Receivable Accounts receivable is recognized initially at fair value and subsequently measured at amortized cost using the effective interest method, less provision for impairment. Accounts receivable expected to be collected over one year is recorded at present value by using predetermined interest rate whereas those expected to be collected within one year are not reported at present value due to the fact that the difference between the maturity value and the fair value discounted by implicit interest rate is immaterial and the frequency of transactions is high. (8) Inventories Inventories are recorded at cost when acquired under a perpetual inventory system. Cost is determined using the weighted-average method. The cost of work in process comprises raw materials, direct labor, other direct costs and related production overheads based on normal operting capacity. As of the balance sheet date, inventories are stated at the lower of cost or net realizable value by item, except where it may be appropriate to similar groups or related items. Net realizable value is the estimated selling price in the ordinary course of business less all estimated costs of completion and necessary selling expenses. In the service agreements with and/or purchase orders from customers, the Group and the customer both agree what materials are to be provided by the customer and what materials are to be provided by the Group. Materials provided by the customers are considered consigned materials. According to the service agreement and/or purchase order, title (ownership) of the consigned materials belongs to the customers. The Group does not take title to these consigned materials. The Group does not have any rights or obligations with respect to the consigned materials other than keeping them in good care while under the Group’s custody, and therefore the risk does not transfer to the Group. In addition, the customers are informed of the status and locations of integrated circuits being assembled and/or tested by the Group which provides further evidence that the customers are taking control or monitoring those consigned materials. As such, the Group does not book the consigned materials into its inventory account. (9) Non-current Assets Held for Sale Non-current assets are classified as held for sale if their carrying amount will be recovered principally through a sale transaction rather than through continuing use. This condition is regarded as met only when the sale is highly probable and the non-current asset held for sale is available for immediate sale in its present condition. To meet the criteria for the sale being highly probable, the appropriate level of management must be committed to the sale, which should be expected to qualify for recognition as a completed sale within one year from the date of classification. Non-current assets classified as held for sale are measured at the lower of their previous carrying amount and fair value less costs to sell. Recognition of depreciation would cease. (10) Financial Assets A. Classification The classification depends on the nature and purpose of acquiring the financial assets and the classification is determined at the time of initial recognition. (a) Loans and receivables Loans and receivables are non-derivative financial assets with fixed or determinable payments that are not quoted in an active market. (b) Available-for-sale financial assets Available-for-sale financial assets are non-derivative financial assets that are either designated in this category or not classified in any of the other categories. Except for those that are expected to be disposed more than one year after the end of the reporting period, which are classified as non-current assets, otherwise, they are classified as current assets. B. Recognition and Measurement (a) Regular purchases and sales of financial assets are recognized on the trade date (the date on which the Group commits to purchase or sell the asset). Financial assets carried at fair value through profit or loss are initially recognized at fair value, and transaction costs are expensed in the statement of comprehensive income. Other financial assets not carried at fair value through profit or losses are initially recognized at fair value plus transaction costs. Financial assets are derecognized when the rights to receive cash flows from the investments have expired or have been transferred and the Group has transferred substantially all risks and rewards of ownership. (b) Financial assets at fair value through profit or loss and available-for-sale financial assets are subsequently carried at fair value. Gains or losses arising from changes in the fair value of the “financial assets at fair value through profit or loss” category are presented in the statement of comprehensive income within “other gains and losses” in the period in which they arise. Changes in the fair value of securities classified as available-for-sale are recognized in other comprehensive income. Dividend income from these two assets is recognized in the statement of comprehensive income when the Group’s right to receive payments is established. (c) Loans and receivables are subsequently carried at amortized cost using the effective interest method. The interest arising subsequently is recognized in “interest income” in the statement of comprehensive income. (d) When securities classified as available-for-sale are sold or impaired, the accumulated fair value adjustments recognized in equity are included in the statement of comprehensive income as “gains and losses from investment securities” and “impairment losses”, respectively. C. Offsetting financial instruments Financial assets and liabilities are offset and the net amount reported in the balance sheet when there is a legally enforceable right to offset the recognized amounts and there is an intention to settle on a net basis or realize the asset and settle the liability simultaneously. The legally enforceable right must not be contingent on future events and must be enforceable in the normal course of business and in the event of default, insolvency or bankruptcy of the company or the counterparty. (11) Impairment of Financial Assets A. Loans and receivables (a) The Group assesses at the end of each reporting period whether there is objective evidence that a financial asset or group of financial assets is impaired. A financial asset or a group of financial asset is impaired and impairment losses are incurred only if: i. There is objective evidence of impairment as a result of one or more events that occurred after initial recognition of the asset (a “loss event”), and ii. That loss event has an impact on the estimated future cash flows of the financial asset or group of financial assets that can be reliably estimated. Evidence of impairment includes: i. The debtor or the issuer is experiencing significant financial difficulty; ii. Default or delinquency in interest or principal payment; iii. Concessions made to the insolvent debtor by creditors owing to economic or legal considerations; iv. The probability that the debtor or debtors will enter bankruptcy or other financial reorganization; v. The disappearance of an active market for that financial asset because of financial difficulties; vi. Where observable data indicates that there is a measurable decrease in the estimated future cash flow, such as: • The repayment condition of the debtor to the Group of assets deteriorated • Changes in areas or economic conditions that correlate with defaults (b) The Group first assesses whether objective evidence of impairment exists individually for financial assets that are individually significant, and individually or collectively for financial assets that are not individually significant. If the Group determines that no objective evidence of impairment exists for an individually assessed financial asset, whether significant or not, it includes the asset in a group of financial assets with similar credit risk characteristics and collectively assesses them for impairment. For these assets, the amount of the loss is measured as the difference between the assets’ carrying amount and the present value of estimated future cash flows (excluding future credit losses that have not been incurred) discounted at the financial asset’s original effective interest rate. The carrying amount of the asset is reduced through the allowance account and the amount of the loss is recognized in the consolidated statement of comprehensive income. In a subsequent period, if the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized (such as an improvement in the debtor’s credit rating), the reversal of the previously recognized impairment loss is recognized in the consolidated statement of comprehensive income. B. Available-for-sale assets The Group assesses at the end of each reporting period whether there is objective evidence that a financial asset or a group of financial assets is impaired. In the case of equity investments classified as available-for-sale, any significant unfavorable change that takes place in the technical, market, economic, or legal environments where the issuer operates indicates the possibility that the investment cost of the equity instrument may not be recovered and a significant or prolonged decline in the fair value of the security below its cost are evidences that the assets are impaired. If any such evidence exists for available-for-sale financial assets, the cumulative loss—measured as the difference between the acquisition cost and the current fair value, less any impairment loss on that financial asset previously recognized in profit or loss is removed from equity and recognized in profit or loss. Impairment losses recognized in the consolidated statement of comprehensive income on equity instruments are not reversed through the consolidated statement of comprehensive income in a subsequent period. (12) Equity Method Investments Investment in associate A. Associates, which are accounted for using the equity method of accounting, are all entities over which the Group has significant influence, which means the power to participate in the financial and operating policy decisions of the investees, but not control or joint control, generally accompanying a shareholding of between 20% and 50% of the voting rights. Under the equity method, the investment is initially recognized at cost, and the carrying amount is increased or decreased to recognize the investor’s share of the profit or loss of the investee after the date of acquisition. The Group’s investment in associates includes goodwill identified on acquisition. B. The Group’s share of post-acquisition profit or loss is recognized in the statement of comprehensive income, and its share of post-acquisition movements in other comprehensive income is recognized in other comprehensive income with a corresponding adjustment to the carrying amount of the investment. When the Group’s share of losses in an associate equals or exceeds its interest in the associate, including any other unsecured receivables, the Group does not recognize further losses, unless it has incurred legal or constructive obligations or made payments on behalf of the associate. C. If the ownership interest in an associate is reduced but significant influence is retained, only a proportionate share of the amounts previously recognized in other comprehensive income is reclassified to profit or loss where appropriate. Dilution gains and losses arising in investments in associates are recognized in the statement of comprehensive income. D. Profits and losses resulting from upstream and downstream transactions between the Group and its associates are recognized in the Group’s financial statements only to the extent of unrelated investor’s interests in the associates. Unrealized losses are eliminated unless the transaction provides evidence of an impairment of the asset transferred. Material accounting policy differences between associates and the Group were properly assessed and changed where necessary to ensure consistency with those adopted by the Group. E. The Group determines at each reporting date whether there is any objective evidence that the investment in the associate is impaired. If this is the case, the Group calculates the amount of impairment as the difference between the recoverable amount of the associate and its carrying value and recognizes the amount in the statement of comprehensive income. (13) Property, Plant and Equipment A. Property, plant and equipment are stated at historical cost less accumulated depreciation and impairments. The acquisition costs include the purchase price, any costs directly attributable to bringing the asset to the location and condition necessary for it to be capable of operating, and the obligations to dismantle and remove the items and restore the site on which they are located. The subsequent costs will only be recognized under the conditions that future economic benefits associated with the item will flow to the Group and the item cost can be measured reliably. The carrying amount of the replaced part is derecognized. Day-to-day servicing costs and repairment expenditures are recognized as expenses as incurred. B. The Group capitalizes borrowing costs that are directly attributable to the acquisition, construction or production of a qualifying asset as part of the cost of that asset. The capitalized borrowing costs will be depreciated through the residual useful lives of related items. Borrowing costs which do not qualify for capitalization are recognized in profit or loss. C. If material part of replacing items of property, plant and equipment has different useful life from the main asset, it should be recognized and depreciated separately. Land is not depreciated. Depreciation on other assets is calculated using the straight-line method to allocate their cost to their residual values over their estimated useful lives. The estimated useful lives of property, plant and equipment are as follows: Property, plant and equipment Estimated useful lives Buildings - Main buildings 20-55 years - Construction and improvements 3-15 years Machinery and equipment 5-6 years Other equipment 2-6 years D. The assets’ residual values and useful lives are reviewed, and adjusted if appropriate, at the end of each fiscal year. Gains and losses on disposals are determined by comparing the proceeds with the carrying amount and are recognized within “Other income and expenses” in the statement of comprehensive income. (14) Intangible Assets Intangible assets are the expenditures of license fees and computer software. License fees are capitalized at historical cost. Acquired computer software is capitalized on the basis of the costs incurred to acquire and bring to use the specific software. Both license fees and computer software are intangible assets with limited useful lives. They are subsequently measured at cost less accumulated amortization and impairment. Computer software is amortized over three years whereas license fees are amortized over their economic lives or the contract years using straight-line method or based on portions of sales. Subsequent measurements are measured using costs less accumulated amortization. (15) Impairment of Non-financial Assets A. Intangible assets with definite useful life and other assets are tested for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. For the purposes of assessing impairment, assets are grouped at the lowest levels for which there are largely independent cash flows (cash-generating units). The recoverable amount is the higher of an asset’s fair value, defined as the price that would be received to dispose an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, less costs to dispose, or it’s value in use. The value in use is the present value of the future cash flows expected to be derived from an asset or cash-generating unit. B. An impairment loss recognized in prior periods for an asset shall be reversed if there has been a change in the estimates used to determine the asset’s recoverable amount since the last impairment loss was recognized. The carrying amount of the asset shall be reversed to its recoverable amount. The increased carrying amount of an asset attributable to a reversal of an impairment loss shall not exceed the carrying amount that would have been determined had no impairment loss been recognized for the asset in prior years. (16) Accounts Payable Accounts payable are obligations to pay for goods or services that have been acquired in the ordinary course of business from suppliers. Accounts payable are recognized initially at fair value and subsequently measured at amortized cost using the effective interest method. Accounts payable of which payment due is within one year or less are not discounted while their fair value are close to the value in maturity and they are transacted actively. (17) Financial liabilities at fair value through profit or loss A. Financial liability is classified in fair value through profit or loss while it is held for trading or identified at fair value through profit or loss on initial recognition. A financial liability is held for trading if it is acquired or incurred principally for the purpose of selling or repurchasing it in the near term, or if it is a derivative that is neither classified as a financial guarantee contract nor designated and effective as a hedging instrument. A financial liability is designated as at fair value through profit or loss upon initial recognition if: i. Such designation eliminates or significantly reduces a measurement or recognition in consistency that would otherwise arise; or ii. The financial liability forms part of a group of financial assets or financial liabilities or both, which is managed and its performance is evaluated on a fair value basis, in accordance with the Group’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or iii. It forms part of a contract containing one or more embedded derivatives, and IAS 39 permits the entire combined contract to be designated as at fair value through profit or loss. B. Financial liabilities at fair value through profit or loss are stated at fair value upon initial recognition, and the related transaction cost are expensed immediately. In subsequent measurement, the Group measures fair value fluctuation in current profit or loss. (18) Convertible Bonds Convertible bonds issued by the Company contain liability, conversion option, redemption option and put option (collectively the “Bonds Options”) components. The Company assesses if the economic characteristics and risks of the redemption option and put embedded in the convertible bonds are closely related to the economic characteristics and risk of the host contract before separating the equity component. For the embedded derivative that is not closely related to the host contract, it is classified as a liability component and subsequently measured at fair value through profit or loss unless it qualifies as an equity component. The equity component is assigned the residual amount after deducting from the fair value of the instrument as a whole the amount separately determined for the liability component. Its carrying amount is not remeasured in the subsequent accounting periods. If the convertible bond issued does not have an equity component, it is accounted for as a hybrid instrument in accordance with the requirements under IAS 39. The conversion option 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 Company’s own equity instruments is classified as a conversion option derivative. At the date of offering, the Bonds Options components are classified as a derivative liability and subsequently measured at fair value through profit and loss. The liability component excluding the Bonds Options is measured at amortized cost using the effective interest method. Transaction costs that relate to the offering of the convertible bonds are allocated to the liability and the Bonds Options components in proportion to their relative fair values. Transaction costs relating to the Bonds Options are recognized immediately in profit or loss. Transaction costs relating to the liability component are included in the carrying amount of the liability component and amortized using the effective interest method. If the convertible bondholders exercise their conversion right before maturity, the Company shall adjust the carrying amount of the liability components. The adjusted carrying amounts of the liability components at conversion are credited to capital stock and capital reserve. In addition, the liability components of convertible bonds is classified as a current liability if within 12 months the bondholders may exercise the put right. After the put right expires, the liability component of the convertible bonds should be reclassified as a non-current liability if it meets the definition of a non-current liability in all other respects. (19) Borrowings Borrowings are recognized initially at fair value, net of transaction costs incurred, and subsequently carried at amortized cost. Any difference between the proceeds, net of transaction costs, and the redemption value is recognized in the statement of comprehensive income over the period of the borrowings using the effective interest method. Fees paid on the establishment of loan facilities are recognized as transaction costs of the loan to the extent that it is probable that some or all of the facility will be drawn down. In this case, the fee is deferred until the draw-down occurs. To the extent there is no evidence that it is probable that some or all of the facility will be drawn down, the fee is capitalized as a prepayment for liquidity services and amortized over the period of the facility to which it relates. (20) Derecognition of financial liabilities A. The Group derecognizes a financial liability from its balance sheet when the obligation specified in the contract is discharged, cancelled or expired. B. The Group derecognizes an original financial liability and recognizes a new financial liability if the terms of an existing financial liability have substantial modifications and such modifications make significant differences (10%) to the original terms. The difference between the carrying amount of the financial liability derecognized and the consideration paid is recognized in profit or loss. (21) Income Tax A. The tax expense for the period comprises current and deferred income tax. Tax is recognized in the income statement, except to the extent that it relates to items recognized in other comprehensive income or directly in equity. In this case, the tax is also recognized in other comprehensive income or directly in equity, respectively. B. The current income tax is calculated on the basis of the tax law enacted or substantively enacted at the balance sheet date in the countries where the Group operates and generates taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in which applicable tax regulation is subject to interpretation. It establishes provisions where appropriate on the basis of amounts expected to be paid to the tax authorities. C. Additional 10% undistributed earnings tax is estimated and recognized during the period when income is earned. D. Deferred income tax is recognized, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated financial statements. However, deferred income tax liabilities are not recognized if they arise from the initial recognition of goodwill; deferred income tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred income tax is determined using tax rates that have been enacted

Critical Accounting Estimates a

Critical Accounting Estimates and Judgments	12 Months Ended
	Dec. 31, 2017
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Critical Accounting Estimates and Judgments	5. Critical Accounting Estimates and Judgments The Group makes estimates and assumptions concerning the future. The resulting accounting estimates may differ from the actual results. The estimates and assumptions that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are addressed below. (1) Pension Benefits The present value of the pension obligations is determined on an actuarial basis. When calculating the present value of defined pension obligations, the Company must apply judgments and estimates to determine a number of actuarial assumptions, including discount rate and future salary growth rate. Any changes in these assumptions could significantly impact the carrying amount of defined pension obligations. For relevant sensitivity analysis, please refer to Note 19. (2) Fair Value of Derivatives and Other Financial Instruments The fair value of derivatives and other financial instruments that are not traded in active market is determined by using valuation techniques. The Group applies professional judgment to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. For valuing these derivatives and other financial instruments, the Group maximizes the use of observable market data where it is available and rely as little as possible on entity specific estimates. For sensitivity analyses, please refer to Note 37C (4). (3) Impairment of available-for-sale equity investments The Company follows the guidance of IAS 39 to determine when an available-for-sale equity investment is impaired. This determination requires significant judgment. In making this judgment, the Company evaluates, among other factors, the duration and extent to which the fair value of an investment is less than its cost; and the financial health of and short-term business outlook for the investee. If the declines in fair value below cost were considered significant or prolonged, the Company would transfer the accumulated fair value adjustments recognized in equity on the impaired available-for-sale financial assets to the statement of comprehensive income. Please refer to Note 10.

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 As of December 31, 2016 2017 NT$ NT$ Cash on hand and petty cash 1,072 1,340 Savings accounts and checking accounts 3,876,568 5,754,845 Time deposits 20,598,630 18,687,898 24,476,270 24,444,083

Accounts Receivable, Net

Accounts Receivable, Net	12 Months Ended
	Dec. 31, 2017
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Accounts Receivable, Net	7. Accounts Receivable, Net As of December 31, 2016 2017 NT$ NT$ Accounts receivable 17,359,584 16,873,044 Less: Allowance for sales discounts (3,006 ) — Allowance for doubtful accounts (1,695 ) (11,933 ) 17,354,883 16,861,111 The Group assessed the carrying value of receivables mentioned above are highly likely to be recovered; therefore, the credit risk is low. Please refer to Note 35 B for relevant analysis. Movements on the Group’s allowance for doubtful accounts are as follows: For the years ended December 31, 2016 2017 NT$ NT$ Balance as of January 1 1,695 1,695 Allowance for doubtful accounts — 11,911 Write-offs — (1,673 ) Balance as of December 31 1,695 11,933 The above movement of allowance for doubtful accounts is based on individual provision.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
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Inventories	8. Inventories As of December 31, 2016 2017 NT$ NT$ Raw materials and supplies 5,885,054 5,406,131 Work in process 613,778 717,551 6,498,832 6,123,682 Amounts recognized in profit or loss are as follows: For the years ended December 31, 2015 2016 2017 NT$ NT$ NT$ Expense / loss incurred related to inventories : Cost of goods sold 61,196,890 65,744,357 66,696,160 Decline in market value and loss on obsolescence 20,320 54,853 69,848 Others 13,412 (37,019 ) (25,718 ) 61,230,622 65,762,191 66,740,290

Non-current Assets Held for Sal

Non-current Assets Held for Sales	12 Months Ended
	Dec. 31, 2017
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Non-current Assets Held for Sales	9. Non-current Assets Held for Sales As of December 31, 2016 2017 NT$ NT$ Plant held for sale 387,503 — On November 3, 2016, the Board of Directors of the Company resolved to sale the plant and its affiliated equipment of Hsinchu facility phase II (No. 15/17, Park Ave. 2, Science-Based Industrial Park, Hsinchu). On December 16, 2016, the Company entered into an agreement to sell the plant to a non-related party. The transfer was completed in March 2017, with a total consideration of $412,000 and the amount has been paid in full. The Company recognized disposal gains of $19,402 on non-current assets held for sale in the first quarter of 2017.

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	10. Available-for-sale Financial Assets As of December 31, 2016 2017 Current Item: NT$ NT$ Fund 178,176 — Non-current Items: Common Stock 3,087,019 4,135,207 Depositary Shares 528,639 — 3,615,658 4,135,207 A. In 2015, the stock price of domestic listed stocks declined significantly below its cost. The Company recognized impairment loss of $1,856,442 as a result of the decline in stock price. These impaired equity securities were subsequently sold in February 2016 and gains on disposal of $10,256 was recognized. The Company disposed common stock of available-for-sale financial assets and recognized gains on disposal of $206,943 in the third quarter of 2016. B. The foreign fund was matured in the first quarter of 2017 and the Company recognized gains on disposal of $53,053. C. The Company held the common stock of ChipMOS Technologies Inc., and the depositary shares of ChipMOS Technologies (Bermuda) Ltd. On October 20, 2016, the Board of Directors of ChipMOS Technologies Inc., has resolved October 31, 2016 as the merger date with ChipMOS Techinologies (Bermuda) Ltd., with ChipMOS Technologies Inc., be the surviving company. Under the agreement, the shareholders of ChipMOS Technologies (Bermuda) Ltd., will receive US$3.71 dollars of cash and 0.9355 unit of American Depository Shares (“ADS”) in exchange for each share in ChipMOS Technologies (Bermuda) Ltd. Each ADS represents 20 new common shares to be issued by ChipMOS Technologies Inc. The Company regarded the merger as business reorganization in substance and only recognized the premium from the merger of $51,923 as other income. The Company converted all ChipMOS ADSs held by the Company into Common Stock of ChipMOS Technologies Inc. in the second quarter of 2017.

Investments Accounted for Using

Investments Accounted for Using Equity Method	12 Months Ended
	Dec. 31, 2017
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Investments Accounted for Using Equity Method	11. Investments Accounted for Using Equity Method Carrying Amount Percentage of ownership interest Associates Nation of Registration December 31, 2016 December 31, 2017 December 31, 2016 December 31, NT$ NT$ Individually immaterial: Yann Yuan Investment Co., Ltd. Taiwan, R.O.C. 2,383,512 2,897,644 33.33% 32.21% ASM Advanced Packaging Materials Pte. Ltd. (AAPM) Singapore 18,019 — 39.00% — 2,401,531 2,897,644 A. The Company acquired common shares of AcSiP Technology Corp. (AcSiP) to upgrade assembly related technology. In December 2015, the Company disposed all of its shareholdings in AcSip and recognized disposal gain of $1,059. B. In December 2015, Siliconware Investment Co., Ltd. (which is the Company’s subsidiary) invested $2,400,000 in Yann Yuan Investment Co., Ltd . Yann Yuan Investment Co., Ltd. held 45,900 thousands shares of SPIL’s common stock as of December 31, 2016 and 2017. In June 2017, Yann Yuan Investment Co., Ltd. issued new shares, which were not subscribed proportionally by the Group. As a result, the Company’s percentage of ownership decreased from 33.33% to 32.21 %. The decrease of net equity on this associate in the amount of $6,645 has been deducted from gain on disposal of investment. The interest previously recognized as other comprehensive income and loss in the amount of $10,425 has been reclassified to investment disposal gains in the second quarter of 2017. C. In order to develop new generation substrates and increase substrate supply sources, the Company acquired the shares in Interconnect Tech Pte. Ltd.. As of September 30, 2015, the carrying amount of investment in Interconnect was $0 and unrecognized share of loss was $133,583 due to the sustained losses of Interconnect. In October 2015, Interconnect sold major assets and liabilities to a newly established company, AAPM, in exchange for cash and 39% interests in AAPM. Concurrently, another third party shareholder contributed cash to acquire 61% interests in AAPM. As a result, the Company evaluated the recoverable amounts of investment in Interconnect using the fair value less cost of disposal model, and reversed the previous impairment charges in “other gains and losses” amounted to $134,992 in 2015 (Note 26). The recoverable amount was determined by referencing to AAPM’s per share price issued to the third party shareholder; therefore, it is considered a Level 2 non-recurring fair value measurement. The Company also recognized previously unrecognized share of loss in Interconnect amounted to $133,583 in 2015. Interconnect subsequently reduced its capital in December 2015. The 39% interests in AAPM were distributed to the Company as capital return. Accordingly, the Company derecognized the investment in Interconnect and recognized a disposal gain of $139,567 in 2015. However, due to the continued losses of AAPM, the carrying amount of investment on AAPM has been written down to $0 as of March 31, 2017. Since the Company did not subscribe on AAPM’s new shares issued in May 2017, the Company’s percentage of ownership on AAPM has been reduced from 39% to13.7%. In addition, because the Company has no longer served as AAPM’s board of director, the Company lost significant influence over AAPM. Due to AAPM’s fair value cannot be reliably measured by the Company and there is no quoted price in an active market, the Company reclassified the investment on AAPM to available-for-sale financial assets and recognized a disposal loss of $1,464 in the second quarter of 2017. D. Set out below are the aggregate carrying value and aggregate amount of the Company’s share of operating results of individually immaterial associates. For the years ended December 31, 2015 2016 2017 NT$ NT$ NT$ Net (loss) income (183,708 ) 3,221 74,035 Other comprehensive income (loss) 1,304 (112,797 ) 380,631 Total comprehensive income (loss) (182,404 ) (109,576 ) 454,666

Financial Instruments by Catego

Financial Instruments by Category	12 Months Ended
	Dec. 31, 2017
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Financial Instruments by Category	12. Financial Instruments by Category As of December 31, 2016 2017 NT$ NT$ Financial Assets Loans and receivables Cash and cash equivalents 24,476,270 24,444,083 Notes receivable 23,591 15,879 Accounts receivable 17,354,883 16,861,111 Other receivables 581,630 492,081 Time deposit pledged as collateral (shown as other current assets-other) 357,400 392,100 Refundable deposit (shown as other non-current assets-other) 501,924 666,936 Available-for-sale financial assets, current 178,176 — Available-for-sale financial assets, non-current 3,615,658 4,135,207 47,089,532 47,007,397 Financial Liabilities Financial liabilities at amortised cost Short-term loans 2,741,250 3,422,400 Accounts payable 8,194,647 7,456,974 Other payables 11,896,517 10,082,704 Receipts under custody (shown as other current liabilities-other) 76,231 74,149 Deposit received (shown as other current liabilities-other and other non-current liabilities) 38,907 60,499 Convertible bonds (including the current portion) 12,712,651 12,015,229 Long-term loans (including the current portion) 18,340,747 15,840,000 Long-term payable (shown as other non-current liabilities) 63,215 5,052 Financial liability at fair value through profit or loss 773,908 809,640 54,838,073 49,766,647

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
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Property, Plant and Equipment	13. Property, Plant and Equipment A. Carrying amount by category: As of December 31, 2016 2017 NT$ NT$ Land 2,903,192 2,903,192 Buildings 19,939,679 21,859,531 Machinery and equipment 32,145,342 30,536,886 Other equipment 4,674,862 4,691,122 Construction in progress and equipment awaiting for inspection 5,717,334 2,407,334 65,380,409 62,398,065 B. Movement from period beginning to period end (a) From January 1, 2015 to December 31, 2015 i. Cost Balance at Additions Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ Land 2,903,192 — — — — 2,903,192 Buildings 22,789,352 1,423,338 — 6,798,051 (57,827 ) 30,952,914 Machinery and equipment 71,922,606 7,675,210 (7,055,018 ) 2,074,177 (232,752 ) 74,384,223 Other equipment 7,629,873 1,192,144 (629,015 ) 737,087 (29,765 ) 8,900,324 Construction in progress and equipment awaiting for inspection 10,018,645 3,719,296 — (9,609,315 ) (19,084 ) 4,109,542 115,263,668 14,009,988 (7,684,033 ) — (339,428 ) 121,250,195 ii. Accumulated depreciation and impairment Balance at Depreciation Impairment Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ NT$ Buildings 9,636,672 1,665,873 — — — (13,561 ) 11,288,984 Machinery and equipment 38,233,303 10,086,128 46,198 (6,977,590 ) 966 (135,539 ) 41,253,466 Other equipment 3,873,022 1,151,771 18,798 (623,394 ) (966 ) (17,094 ) 4,402,137 51,742,997 12,903,772 64,996 (7,600,984 ) — (166,194 ) 56,944,587 (b) From January 1, 2016 to December 31, 2016 i. Cost Balance at Additions Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ Land 2,903,192 — — — — 2,903,192 Buildings 30,952,914 1,445,512 (83,778 ) 428,540 (220,178 ) 32,523,010 Machinery and equipment 74,384,223 7,815,011 (7,204,489 ) 1,542,650 (962,141 ) 75,575,254 Other equipment 8,900,324 1,283,475 (713,787 ) 342,751 (120,433 ) 9,692,330 Construction in progress and equipment awaiting for inspection 4,109,542 4,703,546 (420 ) (2,984,597 ) (110,737 ) 5,717,334 121,250,195 15,247,544 (8,002,474 ) (670,656 ) (1,413,489 ) 126,411,120 ii. Accumulated depreciation and impairment Balance at Depreciation Impairment Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ NT$ Buildings 11,288,984 1,715,407 — (83,778 ) (278,570 ) (58,712 ) 12,583,331 Machinery and equipment 41,253,466 9,849,149 72,655 (7,155,398 ) 3,407 (593,367 ) 43,429,912 Other equipment 4,402,137 1,341,274 18,592 (663,349 ) (9,450 ) (71,736 ) 5,017,468 56,944,587 12,905,830 91,247 (7,902,525 ) (284,613 ) (723,815 ) 61,030,711 (c) From January 1, 2017 to December 31, 2017 i. Cost Balance at Additions Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ Land 2,903,192 — — — — 2,903,192 Buildings 32,523,010 1,376,617 — 2,422,828 (51,686 ) 36,270,769 Machinery and equipment 75,575,254 6,938,086 (3,217,594 ) 2,562,020 (198,414 ) 81,659,352 Other equipment 9,692,330 1,236,677 (464,434 ) 475,464 (28,143 ) 10,911,894 Construction in progress and equipment awaiting for inspection 5,717,334 2,186,703 — (5,460,312 ) (36,391 ) 2,407,334 126,411,120 11,738,083 (3,682,028 ) — (314,634 ) 134,152,541 ii. Accumulated depreciation and impairment Balance at Depreciation Impairment Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ NT$ Buildings 12,583,331 1,841,411 — — — (13,504 ) 14,411,238 Machinery and equipment 43,429,912 10,936,614 78,468 (3,179,598 ) (8,178 ) (134,752 ) 51,122,466 Other equipment 5,017,468 1,637,955 9,763 (434,993 ) 8,178 (17,599 ) 6,220,772 61,030,711 14,415,980 88,231 (3,614,591 ) — (165,855 ) 71,754,476 C. There is no interest capitalized for the years ended December 31, 2015, 2016 and 2017. D. For idle equipment, the Group adopted fair value less cost of disposal method to measure their recoverable amount and recognized impairment loss of $64,996, $91,247 and $88,231 for the years ended December 31, 2015, 2016 and 2017, respectively. The recoverable amount of major impaired property, plant and equipment is determined based on the recent quoted prices of assets with similar age and obsolescence that provided by the vendors in secondary market. The recent quoted prices of assets are a level 2 input in terms of IFRS 13 because the secondary market is not very active. E. In 2016, the Company reclassified the plant held for sale as non-current assets held for sale with cost of $670,656 and accumulated depreciation of $284,613.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
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Intangible Assets	14. Intangible Assets A. Carrying amount by category: As of December 31, 2016 2017 NT$ NT$ License Fee 31,460 18,443 Software 144,402 100,825 175,862 119,268 B. Movement from period beginning to period end (a) From January 1, 2015 to December 31, 2015 i. Cost Item Balance at January 1 Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 608,138 — (495,890 ) — 112,248 Software 174,858 112,692 (84,826 ) (410) 202,314 782,996 112,692 (580,716 ) (410) 314,562 ii. Accumulated amortization Item Balance at January 1 Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 433,876 120,693 (495,890 ) — 58,679 Software 99,950 48,111 (84,826 ) (126) 63,109 533,826 168,804 (580,716 ) (126) 121,788 (b) From January 1, 2016 to December 31, 2016 i. Cost Item Balance at Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 112,248 — (4,354 ) — 107,894 Software 202,314 71,011 (32,320 ) (1,818 ) 239,187 314,562 71,011 (36,674 ) (1,818 ) 347,081 ii. Accumulated amortization Item Balance at Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 58,679 22,109 (4,354 ) — 76,434 Software 63,109 64,616 (32,320 ) (620 ) 94,785 121,788 86,725 (36,674 ) (620 ) 171,219 (c) From January 1, 2017 to December 31, 2017 i. Cost Item Balance at January 1 Additions Disposals Exchange net Balance at NT$ NT$ NT$ NT$ NT$ License Fee 107,894 — (75,094 ) — 32,800 Software 239,187 29,237 (23,689 ) (427) 244,308 347,081 29,237 (98,783 ) (427) 277,108 ii. Accumulated amortization Item Balance at January 1 Additions Disposals Exchange net Balance at NT$ NT$ NT$ NT$ NT$ License Fee 76,434 13,017 (75,094 ) — 14,357 Software 94,785 72,531 (23,689 ) (144) 143,483 171,219 85,548 (98,783 ) (144) 157,840 For the years ended December 31, 2015, 2016 and 2017, amortizations of $14,208, $24,539 and $26,100 are included in “operating cost”, and amortizations of $154,596, $62,186 and $59,448 are included in “operating expense” in the statement of comprehensive income.

Financial Liabilities at Fair V

Financial Liabilities at Fair Value Through Profit or Loss	12 Months Ended
	Dec. 31, 2017
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Financial Liabilities at Fair Value Through Profit or Loss	15. Financial Liabilities at Fair Value Through Profit or Loss As of December 31, 2016 and 2017, the detail of financial liabilities at fair value through profit or loss is as follow: As of December 31, 2016 2017 NT$ NT$ Conversion option, redemption option and put option of convertible bonds upon initial recognition(Note 17) 774,319 774,319 Valuation adjustments (411 ) 35,321 773,908 809,640 For the years ended December 31, 2015, 2016 and 2017, the Company recognized net losses of $703,368, gains of $1,025,012 and losses of $35,732 on financial liabilities at fair value through profit or loss, respectively.

Other Payables

Other Payables	12 Months Ended
	Dec. 31, 2017
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Other Payables	16. Other Payables As of December 31, 2016 2017 NT$ NT$ Payables for equipment 3,486,635 2,234,142 Payables for employees’ compensations 3,880,980 3,476,527 Others 4,528,902 4,372,035 11,896,517 10,082,704 Others represent individually insignificant items such as supplies, maintenance charges, professional service fees and etc., which are presented on an aggregate basis.

Convertible Bonds

Convertible Bonds	12 Months Ended
	Dec. 31, 2017
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Convertible Bonds	17. Convertible Bonds As of December 31, 2016 and 2017, the detail of convertible bonds is as follow: As of December 31, 2016 2017 NT$ NT$ Unsecured overseas convertible bonds 13,580,212 12,533,316 Less: Discounts on bonds payable (867,561 ) (518,087 ) Current portion (12,712,651 ) — — 12,015,229 In October 2014, the Company issued the fourth unsecured overseas convertible bonds (the “Bonds”) in US$400,000 thousand. The Bonds are zero coupon bonds with a maturity of 5 years and with par value of US$250 thousand or in any integral multiples thereof. Key terms and conditions of the Bonds are as follows: A. Each holder of the Bonds has the right to convert at any time starting from the day immediately following 40 days after the issue date to 10 days prior to the maturity date, except during legal lock-up period, into newly issued listed common shares or American Depository shares (“ADSs”) at the conversion price NT$53.1038 dollars, determined on the basis of a fixed exchange rate of US$1 to NT$30.392 (in dollars). The conversion price was adjusted to $44.1443 dollars as of December 31, 2017. B. Unless previously redeemed, repurchased and cancelled, or converted, the Bonds will be redeemed by the Company on the maturity date at an amount equal to 105.11% of the principals, with repayment made in US dollars. C. 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) at 103.04% of the principal amount on the third anniversary of the issuance date or (2) at principal amount plus 1% interest compounded semiannually (“Early Redemption Amount”) in the event of a change in control or delisting. D. The Company may redeem the Bonds in whole or in part, from 3 years after the issuance date, at a price equal to the Early Redemption Amount, provided that the closing price of the Company’s common shares on the Taiwan Stock Exchange, converted into US dollars at the prevailing exchange rate, on 20 trading days within a period of 30 consecutive trading days, is at least 130% of the Early Redemption Amount divided by the conversion ratio. The Company may, in whole but not in part, redeem all of the Bonds at the Early Redemption Amount in the event that more than 90% of the Bonds have been previously redeemed, converted, or repurchased or cancelled, or in the event of changes in the R.O.C.’s tax rules which result in significant unfavorable tax consequences to the Company. E. The Bonds contained a debt host contract, recognized as convertible bonds, and the Bonds Options were aggregately recognized as financial liabilities at fair value through profit or loss. The effective interest rate of the debt host contract was 2.407% and the aggregate fair value of the Bonds Options was $774,319 on initial recognition. F. For the years ended December 31, 2015, 2016 and 2017, the interest expenses on corporate bonds payable were $300,672, $306,423 and $289,671, respectively. G. On February 12, 2018, the Company convened an extraordinary general meeting to resolve the Joint Share Exchange Agreement, Supplemental Agreement to Joint Share Exchange Agreement and the transaction completed by the Joint Share Exchange Agreement with Advanced Semiconductor Engineering, Inc. On the same day, the Board of Directors resolved April 30, 2018 as the effective date of the Share Exchange Transactions and the delisting date of the Company’s shares. As a result of the event described above, a Delisting Event and a Change of Control Event of the Indenture will occur on April 30, 2018, and the Delisting Repurchase Date to be April 13, 2018. Therefore, the Bond holder shall have the right to request the Company repurchase the Bond in the amount indicated in Note 17C above when the application period from February 14 to April 3, 2018.

Loans

Loans	12 Months Ended
	Dec. 31, 2017
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Loans	18. Loans A. Short-term Loans As of December 31, 2016 2017 NT$ NT$ Credit loans 2,741,250 3,422,400 Interest rates 1.3250% ~ 1.6440% 1.6764% ~ 2.5112% B. Long-term Loans Loan period and repayment method As of December 31, 2016 2017 NT$ NT$ Syndicated bank loans: 2012.8.10-2017.8.10 Including US$33,333 thousand in December 31, 2016. Repayables in 6 semi-annually installments starting from February, 2015 2,162,333 — Other bank loans: 2013.12.31-2016.12.31 /Extended to 2019.12.30, and increased by $1,000,000 on 2017.01.19. Repayables in 3 semi-annually installments starting from December 28, 2018 1,500,000 2,500,000 2014.8.11-2018.12.13 Repayables in 5 semi-annually installments starting from December 13, 2016 680,000 340,000 2014.8.11-2018.12.10 Repayables in 6 semi-annually installments starting from June 13, 2016 1,000,000 500,000 2014.8.11-2019.8.11 Repayables in 6 semi-annually installments starting from February 10, 2017 1,500,000 1,000,000 2015.7.1-2020.7.1 Repayables in 6 semi-annually installments starting from January 2, 2018 1,500,000 1,500,000 2015.11.13-2020.11.13 Repayables in 6 semi-annually installments starting from May 11, 2018 1,000,000 1,000,000 2016.07.19-2021.01.10 Repayables in 6 semi-annually installments starting from July 10, 2018 3,000,000 3,000,000 2016.07.19-2021.07.19 Repayables in 6 semi-annually installments starting from January 18, 2019 4,000,000 4,000,000 2016.12.30-2021.12.30 Repayables in 6 semi-annually installments starting from June 28, 2019 2,000,000 2,000,000 Less: Arrangement fee of syndicated loans (1,586 ) — Current portion (3,500,747 ) (3,173,333 ) 14,840,000 12,666,667 Interest rate 1.1287%-2.3890% 1.1358%-2.3890% (1) In order to fulfill the requirements of operational and capital expenditures, the Company entered into syndicated loan agreements with eleven financial institutions, including Mega International Commercial Bank, the management bank, in August 2012. All long-term loans are with credit periods of five years and are floating interest rate loans. (2) Pursuant to the loan agreement, the Company should maintain, on a semi-annual and annual consolidated basis, certain debt covenants, such as current ratio, liability to tangible net worth ratio as well as the ratio of interest coverage. Up to December 31, 2017, the Company has been in compliance with all the debt covenants.

Post-employment Benefit

Post-employment Benefit	12 Months Ended
	Dec. 31, 2017
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Post-employment Benefit	19. Post-employment Benefit A. Defined Benefit Plan In accordance with the Labor Standards Law, the Company has a funded defined benefit pension plan covering all eligible employees prior to the enforcement of the Labor Pension Act (“the Act”), which becomes effective on July 1, 2005, and those employees who choose to stay with the pension mechanism under the Labor Standards Law after the enforcement of the Act. Pension benefits are generally based on service years and six-month average wages and salaries before retirement of the employee. Two units are earned per year for the first 15 years of service and one unit is earned for each additional year of service with a maximum of 45 units. Under the funding policy of the plan, the Company contributes monthly an amount equal to 2% of the employees’ monthly salaries and wages to the pension fund, which is administered by the Labor Pension Fund Supervisory Committee (the Committee) and deposited in the names of the Committees in the Bank of Taiwan. Also, the Company would assess the balance in the aforementioned labor pension reserve account by the end of December 31, every year. If the account balance is not enough to pay the pension calculated by the aforementioned method, to the labors expected to be qualified for retirement next year, the Company will make contribution for the deficit by next March. The Company established pension plans for executive officers and recognized $63,007 and $596 net of pension costs for the years ended December 31, 2016 and 2017 respectively. As of December 31, 2016 and 2017, the net defined benefit obligations of executive officers were $64,929 and $62,222, respectively. (1) Except for the pension plans for executive officers, the amounts arising from the defined benefit obligation recognized on the balance sheets are as follows: As of December 31, 2016 2017 NT$ NT$ Present value of defined benefit obligations 2,550,824 2,513,060 Fair value of plan assets (1,177,592 ) (1,159,337 ) Net defined benefit liability 1,373,232 1,353,723 (2) Movements in net defined benefit liabilities are as follows: (a) For the year ended December 31, 2015 Present value of Fair value of Net defined NT$ NT$ NT$ Balance at January 1 2,225,935 (1,192,196 ) 1,033,739 Current service cost 20,475 — 20,475 Interest expense (income) 49,670 (26,976 ) 22,694 70,145 (26,976 ) 43,169 Remeasurements: Experience adjustments 10,493 — 10,493 Changes in demographic assumptions 18,021 — 18,021 Changes in financial assumptions 145,514 — 145,514 Return of plan assets(excluding amount included in net interest expense) — 5,814 5,814 174,028 5,814 179,842 Pension fund contribution — (49,440 ) (49,440 ) Paid Pension (77,827 ) 77,827 — Balance at December 31 2,392,281 (1,184,971 ) 1,207,310 (b) For the year ended December 31, 2016 Present value of Fair value of Net defined NT$ NT$ NT$ Balance at January 1 2,392,281 (1,184,971 ) 1,207,310 Current service cost 19,165 — 19,165 Interest expense (income) 41,441 (20,754 ) 20,687 60,606 (20,754 ) 39,852 Remeasurements: Experience adjustments 19,709 — 19,709 Changes in financial assumptions 149,878 — 149,878 Return of plan assets(excluding amount included in net interest expense) — 6,297 6,297 169,587 6,297 175,884 Pension fund contribution — (49,814 ) (49,814 ) Paid Pension (71,650 ) 71,650 — Balance at December 31 2,550,824 (1,177,592 ) 1,373,232 (c) For the year ended December 31, 2017 Present value of Fair value of Net defined NT$ NT$ NT$ Balance at January 1 2,550,824 (1,177,592 ) 1,373,232 Current service cost 17,171 — 17,171 Interest expense (income) 37,817 (17,601 ) 20,216 54,988 (17,601 ) 37,387 Remeasurements: Experience adjustments (13,625 ) — (13,625 ) Return of plan assets(excluding amount included in net interest expense) — 6,281 6,281 (13,625 ) 6,281 (7,344 ) Pension fund contribution — (49,552 ) (49,552 ) Paid Pension (79,127 ) 79,127 — Balance at December 31 2,513,060 (1,159,337 ) 1,353,723 (3) Under the Labor Standards Law, the rate of return on assets shall not be less than the average interest rate on a two-year time deposit published by the local banks and the government is responsible for any shortfall in the event that the rate of return is less than the required rate of return. The plan assets are held in a commingled fund which is operated and managed by the government’s designated authorities; as such, the Company does not have any right to intervene in the investments of the Funds. The constitution of fair value of plan assets as of December 31, 2016 and 2017 is as follows: As of December 31, 2016 2017 NT$ NT$ Cash 268,962 270,473 Equity instruments 580,435 574,452 Debt instruments 328,195 314,412 1,177,592 1,159,337 (4) Principal actuarial assumptions for the reporting period are as follows: As of December 31, 2016 2017 Discount rate 1.50 % 1.50 % Future salary increases 2.25 % 2.25 % (5) For the years ended December 31, 2016 and 2017, if the aforementioned discount rate and future salary increase rate are 0.5% higher (lower) than management’s estimates, the impact on the carrying amounts of defined benefit obligations is as follows: Impact on defined benefit obligations As of December 31, 2016 0.5% increase in 0.5% decrease in NT$ NT$ Discount rate (150,030 ) 163,143 Future salary increase rate 161,138 (149,723 ) Impact on defined benefit obligations As of December 31, 2017 0.5% increase in 0.5% decrease in NT$ NT$ Discount rate (139,783 ) 151,499 Future salary increase rate 149,644 (139,499 ) The above sensitivity analyses are based on a change in an assumption while holding all other assumptions constant. In practice, this is unlikely to occur, and changes in some of the assumptions may be correlated. When calculating the sensitivity of the defined benefit obligations to significant actuarial assumptions, the same method has been applied as when calculating the net defined benefit liability recognized in the balance sheet. (6) The Company expects to pay $50,667 as contribution to the pension plan in 2018. (7) As of December 31, 2017, the weighted average duration of the defined benefit plan is 11.6 years. Expected maturity analysis of undiscounted defined benefit obligations was as follows: NT$ Within 1 year 65,895 1-2 year(s) 73,658 2-3 years 87,648 Over 3 years 2,876,889 3,104,090 B. Defined Contribution Plans (1) In accordance with the Labor Pension Act (“LPA”), effective July 1, 2005, the Company has established a defined contribution pension plan covering all regular employees with R.O.C. nationality. The Company makes monthly contributions to the employees’ individual pension accounts on a basis no less than 6% of each employee’s monthly salary or wage. The principal and accumulated gains or losses from an employee’s personal pension account may be claimed on a monthly basis or on lump sum. (2) SUI has established a 401(K) pension plan (“the Plan”) covering substantially all employees. The Plan provides voluntary salary reduction contributions by eligible participants in accordance with Section 401(K) of the U.S. Internal Revenue Code, as well as discretionary matching contributions determined annually by its Board of Directors to employees’ individual pension accounts. (3) In accordance with the regulatory requirements in Suzhou and Quanzhou, PRC, Siliconware Technology (Suzhou) Limited and Siliconware Electronics (Fujian) Co., Limited contribute monthly an amount equal to certain percentage of employees’ monthly salaries and wages to the Bureau of Social Insurance. Other than the monthly contributions, Siliconware Technology (Suzhou) Limited and Siliconware Electronics (Fujian) Co., Limited have no further obligations. (4) The expenses recognized for the Group’s defined contribution pension plans are $533,905, $552,706 and $731,170 for the years ended December 31, 2015, 2016 and 2017, respectively.

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2017
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Capital Stock	20. Capital Stock A. As of December 31, 2016 and 2017, the authorized capital of the Company was $36,000,000 and the paid-in-capital was $31,163,611 with par value of NT$10 (in dollars) per share. B. The Company issued $1,500,000 American Depositary Shares (“ADSs”), represented by 30,000,000 units of ADSs. Each ADS represents five shares of common stock of the Company with an offering price of US$8.49 (in dollars) per ADS. As of December 31, 2016 and 2017, the outstanding ADSs amounted to 37,783,392 units and 35,557,636 units, respectively. Major terms and conditions of the ADSs are summarized as follows: (1) Voting Rights ADS holders will have no rights to vote directly in stockholders’ meetings with respect to the Deposited Shares. The Depositary shall provide voting instruction to the Chairman of the Company and vote on behalf of the Deposited shares evidenced by ADSs. If the Depositary receives voting instructions from holders of at least 51% of the outstanding ADSs to vote in the same direction on a resolution, the Depositary will vote in the manner as instructed. (2) Distribution of Dividends ADS holders are deemed to have the same rights as holders of common shares with respect to the distribution of dividends.

Capital Reserve

Capital Reserve	12 Months Ended
	Dec. 31, 2017
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Capital Reserve	21. Capital Reserve A. Pursuant to the Company Law of the R.O.C., the capital reserve arising from paid-in capital in excess of par on the issuance of stocks, from donation shall be exclusively used to cover accumulated deficits or transferred to capital proportionally either in issuing common stock or in returning cash. Other capital reserves shall be exclusively used to cover accumulated deficits. The amount of capital reserve used to increase capital is limited to 10% of the common stock each year when the Company has no accumulated deficits. The capital reserve can only be used to cover accumulated deficits when the legal reserve is insufficient to cover the deficits. B. According to the Company Law of the R.O.C., capital reserve is allowed to be transferred to share capital in the following year after the registration of capitalization is approved by the government authority. C. Distribution from capital reserve of $3,116,361 (NT$ 1.0 dollar per share) had been resolved at the stockholders’ meeting on May 16, 2016 and resolved in the Board of Director’s meeting that July 1, 2016 as the ex-dividend date.

Retained Earnings

Retained Earnings	12 Months Ended
	Dec. 31, 2017
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Retained Earnings	22. Retained Earnings A. According to the Company’s Articles of Incorporation, current year’s earnings before tax, if any, shall be distributed in the following order: (1) Payment of taxes and dues; (2) Completing the deficit and losses; (3) Set aside 10% for statutory surplus reserve, unless the statutory surplus reserve has reached the total capital; (4) Set aside or reverse special reserves; (5) Any further remaining amount shall be added to the unallocated surplus from the prior year as shareholder dividend and bonus. The Board of Directors shall draft a proposal to distribute the surplus, which shall be approved at a shareholders’ meeting. B. Dividends may be distributed by way of cash dividend and stock dividend. Distribution shall be made preferably by way of cash dividend while cash dividend shall be more than 50% of total dividends to be distributed. The amount is subject to the resolution adopted by the Board of Directors and approved at the Shareholders’ Meeting. Dividend distribution to the Company’s shareholders is recognized as liability in the Company’s financial statements in the period in which the dividends are approved. C. Legal reserve can only be used to offset deficits or increase capital in issuing common stock or in distributing cash. The amount of legal reserve that may be used to increase capital shall be limited to the portion of the reserve balance exceeding 25% of the capital stock. D. In accordance with the R.O.C. Securities and Future Bureau (SFB) regulations, in addition to legal reserve, the Company should set aside a special reserve from the debit balance on other equity items at the balance sheet date before distributing earnings. When debit balance on other equity items is reversed subsequently, the reserved amount could be included in the distributable earnings. E. The Taiwan imputation tax system requires that any undistributed current earnings of a company derived on or after January 1, 1998 to be subject to an additional 10% corporate income tax if the earnings are not distributed in the following year. As of December 31, 2016 and 2017, the undistributed earnings derived on or after the implementation of the imputation tax system were $10,252,276 and $10,698,848, respectively. F. As of December 31, 2016 and 2017, the balances of shareholders’ imputation tax credit account of the Company were $482,903 and $873,827, respectively. The rate of shareholders’ imputation tax credit to undistributed earnings for the 2016 earnings distribution was 10.50%. Effective from 2018, the Integrated Income Tax System will be cancelled under the amendment of Income Tax Law passed in February 2018. Therefore, the Company does not need to calculate the rate of shareholders’ imputation tax credit to undistributed earnings for the earnings distribution as of December 31, 2017. However, the rate is subject to changes based on the balance of shareholders’ imputation tax credit account, the undistributed earnings, and other tax credit amount in accordance with the R.O.C. tax law at the dividend distribution date. Effective from January 1, 2015, the creditable ratio for individual shareholders residing in the R.O.C. will be half of the original creditable ratio according to the revised Article 66-6 of the Income Tax Law. G. The appropriations of 2015 and 2016 earnings have been approved at the Shareholders’ meeting on May 16, 2016 and June 28, 2017, respectively. The appropriations and dividends per share were as follows: For the Years Ended December 31, 2015 2016 Amount Dividends Amount Dividends NT$ NT$ Provision of Legal reserve 876,226 993,316 Cash dividends 8,725,811 2.80 5,453,632 1.75 H. As of March 22, 2018, the Company’s Board of Directors has not approved the earnings distribution for 2017. I. Since the 2018 Shareholders’ meeting has yet to be held, there is uncertainty on the 2017 earnings distribution. In accordance with IAS 12, the Group accrued additional 10% tax on undistributed earnings in full. Income tax effect on dividend distribution is reversed and adjusted to tax expenses and related income tax payables in the following year when shareholders resolve the earnings distribution plan. As of December 31, 2017, the additional 10% tax payable of $629,353 was recognized in “Other non-current liabilities” on the balance sheet. Potential income tax consequence on dividend distribution adjusts based on the approved earnings distribution by the shareholders’ meeting.

Other Equity Items

Other Equity Items	12 Months Ended
	Dec. 31, 2017
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Other Equity Items	23. Other Equity Items Unrealized Gain on Valuation of Available-for- Exchange Difference on Remeasurements of NT$ NT$ NT$ As of January 1, 2015 3,670,115 720,253 23,339 Changes in fair value of financial instruments - pretax (2,406,287 ) — — - tax 19,610 — — Recognition of changes in fair value of financial instruments in profit or loss - pretax 1,856,442 — — Differences in translation - equity method investments - pretax — (223,940 ) — - tax — (40 ) — Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method - pretax — (3,965 ) — - tax — 674 — Remeasurements of post-employment benefit obligations - pretax — — (179,842 ) - tax — — 30,572 As of December 31, 2015 3,139,880 492,982 (125,931 ) Unrealized Gain on Valuation of Available-for- Exchange Difference on Remeasurements of NT$ NT$ NT$ As of January 1, 2016 3,139,880 492,982 (125,931 ) Changes in fair value of financial instruments - pretax (1,229,348 ) — — - tax 242,555 — — Recognition of changes in fair value of financial instruments in profit or loss - pretax (239,757 ) — — - tax 19,804 — — Share of other comprehensive income of associates - pretax (121,957 ) — — - tax 10,981 — — Differences in translation - equity method investments - pretax — (908,801 ) — - tax — 570 — Remeasurements of post-employment benefit obligations - pretax — — (177,806 ) - tax — — 30,227 As of December 31, 2016 1,822,158 (415,249 ) (273,510 ) Unrealized Gain on Valuation of Available-for- Exchange Difference on Remeasurements of NT$ NT$ NT$ As of January 1, 2017 1,822,158 (415,249 ) (273,510 ) Changes in fair value of financial instruments - pretax 519,549 — — - tax (63,395 ) — — Recognition of changes in fair value of financial instruments in profit or loss - pretax (54,374 ) — — - tax 13,734 — — Share of other comprehensive income of associates - pretax 418,944 — — - tax (37,721 ) — — Differences in translation - equity method investments - pretax — (227,787 ) — - tax — 111 — Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method - pretax — 1,464 — - tax — (305 ) — Remeasurements of post-employment benefit obligations - pretax — — 10,647 - tax — — (1,810 ) As of December 31, 2017 2,618,895 (641,766 ) (264,673 )

Expenses by Nature

Expenses by Nature	12 Months Ended
	Dec. 31, 2017
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Expenses by Nature	24. Expenses by Nature For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Employee benefit expenses Salaries and bonuses 15,339,459 16,155,821 15,041,087 Post employment benefits 577,074 655,565 769,153 Directors’ remuneration 112,801 127,111 91,750 Others 2,026,237 2,190,194 2,607,597 18,055,571 19,128,691 18,509,587 Depreciation and amortization expenses 13,513,985 13,291,190 14,625,299 A. In accordance with the Company’s Articles of Incorporation, after covering accumulated losses, 10% of the annual profit shall be set aside as employees’ compensation. Additionally, 1% or less of the annual profit shall be set aside as directors’ remuneration. Employees’ compensation is payable, in the form of cash or shares, to the payroll employees of the Company or its domestic or foreign subsidiaries over which the Company has 50% or more of voting power, who work substantially during the fiscal year in which the annual profit is generated. B. For the years ended December 31, 2015, 2016 and 2017, employee compensation was accrued at 10% in the amounts of $1,128,007, $1,271,115 and $917,496, respectively; directors’ remuneration was accrued at 1% in the amounts of $112,801, $127,111 and $91,750, respectively. Both are paid/ payable in the form of cash. In 2015, 2016 and 2017, the employees’ compensation and directors’ remuneration were estimated and accrued based on the annual profits for the years ended December 31, 2015, 2016 and 2017.

Other Income and Expenses

Other Income and Expenses	12 Months Ended
	Dec. 31, 2017
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Other Income and Expenses	25. Other Income and Expenses For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Loss on damages and claims (374,613 ) (298,778 ) (120,744 ) Gains on disposal of property, plant and equipment and other assets 31,293 32,615 150,579 Gains on disposal of non-current assets held for sales — — 19,402 Impairment loss on property, plant and equipment (64,996 ) (91,247 ) (88,231 ) Others 152,499 240,404 166,040 (255,817 ) (117,006 ) 127,046

Other Gains and Losses, Net

Other Gains and Losses, Net	12 Months Ended
	Dec. 31, 2017
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Other Gains and Losses, Net	26. Other Gains and Losses, Net For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Foreign exchange gain (loss)—net (77,439 ) (104,365 ) 39,976 Gains on reversal of impairment loss of non-financial assets (Note 11(C)) 134,992 — — 57,553 (104,365 ) 39,976

Income Tax

Income Tax	12 Months Ended
	Dec. 31, 2017
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Income Tax	27. Income Tax A. Income taxes recognized in profit or loss for the years ended December 31, 2015, 2016 and 2017 are as follows: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Current income tax expense Recognition for the current period 1,741,385 1,356,232 1,188,463 Provision of additional 10% tax on undistributed earnings 906,273 904,395 982,843 Reversal of additional 10% tax on undistributed earnings due to dividend distribution (1,056,043 ) (788,603 ) (904,395 ) Income tax adjustments for prior years (39,435 ) (6,336 ) (6,759 ) 1,552,180 1,465,688 1,260,152 Deferred income tax expense Temporary differences (186,121 ) 401,511 265,427 Income tax expense recognized in profit or loss 1,366,059 1,867,199 1,525,579 B. The tax on the Group’s profit before tax differs from the theoretical amount that would arise using the weighted average tax rate applicable to profits of the consolidated entities as follows: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Income tax expense calculated at the statutory tax rates applicable to respective countries 2,057,890 2,300,048 1,783,328 Expense disallowed (deductible income) by tax regulation 319,835 113,971 (13,203 ) Tax exempt income by tax regulation (736,103 ) (572,372 ) (389,163 ) Temporary difference not recognized as deferred income tax liabilities (179,130 ) (156,588 ) (135,960 ) Change in assessment of realization of deferred income tax assets (1,071 ) — — Effect from Alternative Minimum Tax 88,944 72,684 32,688 Provision of additional 10% tax on undistributed earnings 906,273 904,395 982,843 Adjustment: over provision from prior years (1,090,579 ) (794,939 ) (911,703 ) Deferred tax effect of earnings of subsidiaries — — 176,749 Income tax expense recognized in profit or loss 1,366,059 1,867,199 1,525,579 The weighted average statutory tax rates applicable to respective countries for the years ended December 31, 2015, 2016 and 2017 were 19.83%, 19.70% and 20.50%, respectively. Adjustment for over provision from prior years mainly relates to the reversal of additional 10% income tax effect on dividend distribution. Refer to Note 22(I) for more information. C. Income taxes recognized in other comprehensive income for the years ended December 31, 2015, 2016 and 2017 are as follows: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Unrealized gain/loss on available-for-sale financial assets 19,610 262,359 (49,661 ) Share of other comprehensive income of associates — 10,981 (37,721 ) Exchange difference on translation of foreign financial statements 634 570 (194 ) Remeasurements of post-employment benefit obligation 30,572 30,227 (1,810 ) 50,816 304,137 (89,386 ) D. Changes in deferred income tax assets and liabilities for the years ended December 31, 2015, 2016 and 2017 are as follows: For the Year Ended December 31, 2015 January 1 Profit or Other Effect of December 31 NT$ NT$ NT$ NT$ NT$ Deferred income tax assets Temporary differences Unrealized sales allowance 47,722 (43,330 ) — (40 ) 4,352 Convertible bonds 95,623 125,131 — — 220,754 Post-employment benefit obligations 165,371 (2,254 ) 30,572 — 193,689 Unrealized losses on financial liabilities at fair value through profit or loss 54,610 119,572 — — 174,182 Others 332,786 (13,352 ) 634 (991 ) 319,077 696,112 185,767 31,206 (1,031 ) 912,054 Deferred income tax liabilities Temporary differences Unrealized gains on available-for-sale financial assets (282,648 ) — 19,610 — (263,038 ) Unrealized gains on property, plant and equipment (13,567 ) (14,828 ) — 697 (27,698 ) Others (60,003 ) 15,182 — 972 (43,849 ) (356,218 ) 354 19,610 1,669 (334,585 ) Net deferred income tax assets 339,894 186,121 50,816 638 577,469 For the Year Ended December 31, 2016 January 1 Profit or Other Effect of December 31 NT$ NT$ NT$ NT$ NT$ Deferred income tax assets Temporary differences Unrealized sales allowance 4,352 (1,807 ) — (151 ) 2,394 Convertible bonds 220,754 11,828 — — 232,582 Post-employment benefit obligations 193,689 19,610 30,227 — 243,526 Unrealized losses on financial liabilities at fair value through profit or loss 174,182 (174,182 ) — — — Others 319,077 (43,697 ) 570 (1,740 ) 274,210 912,054 (188,248 ) 30,797 (1,891 ) 752,712 Deferred income tax liabilities Temporary differences Unrealized gains on available-for-sale financial assets (263,038 ) (139,835 ) 262,359 — (140,514 ) Unrealized gains on property, plant and equipment (27,698 ) (39,646 ) — 4,828 (62,516 ) Others (43,849 ) (33,782 ) 10,981 5,320 (61,330 ) (334,585 ) (213,263 ) 273,340 10,148 (264,360 ) Net deferred income tax assets 577,469 (401,511 ) 304,137 8,257 488,352 For the Year Ended December 31, 2017 January 1 Profit or Other Effect of December 31 NT$ NT$ NT$ NT$ NT$ Deferred income tax assets Temporary differences Convertible bonds 232,582 (120,794 ) — — 111,788 Post-employment benefit obligations 243,526 (12,559 ) (1,810 ) — 229,157 Unrealized losses on inventories 50,380 19,594 — (231 ) 69,743 Provisions 70,678 (29,175 ) — — 41,503 Compensated absences payable 69,876 3,469 — (36 ) 73,309 Others 85,670 30,536 (26,935 ) (38 ) 89,233 752,712 (108,929 ) (28,745 ) (305 ) 614,733 Deferred income tax liabilities Temporary differences Gains from investment for using equity method — (176,749 ) — — (176,749 ) Unrealized gains on available-for-sale financial assets (140,514 ) (21,291 ) (49,660 ) — (211,465 ) Unrealized gains on property, plant and equipment (62,516 ) 1,864 — 1,219 (59,433 ) Others (61,330 ) 39,678 (10,981 ) 697 (31,936 ) (264,360 ) (156,498 ) (60,641 ) 1,916 (479,583 ) Net deferred income tax assets 488,352 (265,427 ) (89,386 ) 1,611 135,150 E. Unrecognized deferred income tax liabilities relating to the taxable temporary differences for investments in foreign subsidiaries are: As of December 31, 2016 2017 NT$ NT$ Investment in foreign subsidiaries 6,693,787 7,266,412 F. The Company has met the requirement of “Incentives for Emerging Important Strategic Industries in Manufacturing and Technology Services” for its capitalization plans in 2007 and is exempted from income tax for revenues arising from the assembly and testing of certain integrated circuit products for a five-year period from 2015. The Company selected 2015 as the starting periods of the five-year income tax exemptions will expire in December 2019. As a result of the above tax holiday, the net income was higher by $488,100 ($0.16 dollars per share), $354,353 ($0.11 dollars per share) for the years ended December 31, 2016 and 2017, respectively. G. The income tax returns of the Company have been assessed and approved by the Tax Authority through 2015. H. According to the amended Enterprise Income Tax Law of the Peoples’ Republic of China, the tax rate adopted in subsidiary, Siliconware Technology (Suzhou) Limited and Siliconware Electronics (Fujian) Co., Limited is 25%.

Earnings Per Share (EPS)

Earnings Per Share (EPS)	12 Months Ended
	Dec. 31, 2017
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Earnings Per Share (EPS)	28. Earnings Per Share (EPS) For the year ended December 31, 2015 Income after tax Weighted average Earnings per share NT$ (in thousands) NT$ Basic earnings per share Net income 9,011,463 3,116,361 2.89 Dilutive effect of employee compensation — 33,769 Diluted earnings per share 9,011,463 3,150,130 2.86 For the year ended December 31, 2016 Income after tax Weighted average Earnings per share NT$ (in thousands) NT$ Basic earnings per share Net income 9,806,937 3,116,361 3.15 Dilutive effect of employee compensation — 28,643 Dilutive effect of convertible bonds (779,928 ) 265,677 Diluted earnings per share 9,027,009 3,410,681 2.65 For the year ended December 31, 2017 Income after tax Weighted average Earnings per share NT$ (in thousands) NT$ Basic earnings per share Net income 7,171,534 3,116,361 2.30 Dilutive effect of employee compensation — 22,122 Dilutive effect of convertible bonds (549,203 ) 275,388 Diluted earnings per share 6,622,331 3,413,871 1.94 A. Basic earnings per share is calculated by dividing the profit attributable to equity holders of the Company by the weighted average number of ordinary shares in issue during the period excluding ordinary shares held as treasury stocks. B. Diluted earnings per share is calculated by adjusting the weighted average ordinary shares oustanding to assume conversion of all dilutive potential ordinary shares. The convertible bonds were not included in the calculation of diluted earnings per share for the years ended December 31, 2015 because they were antidilutive. C. As employees’ compensation could be distributed in the form of stock, the diluted EPS computation shall include those estimated shares that would be increased from employees’ stock bonus issuance in the weighted-average number of common shares outstanding during the reporting year, which taking into account the dilutive effects of stock bonus on potential common shares; whereas, basic EPS shall be calculated based on the weighted-average number of common shares outstanding during the reporting year that include the shares of employees’ stock bonus for the appropriation of prior year earnings, which have already been resolved at the stockholders’ meeting held in the reporting year.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2017
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Supplemental Cash Flow Information	29. Supplemental Cash Flow Information A. Investment activities with partial cash payments For the years ended December 31, 2015 2016 2017 NT$ NT$ NT$ Purchase of property, plant and equipment 14,009,988 15,247,544 11,738,083 (Decrease)/ increase in prepayment for equipment (4,798 ) 21,754 (32,435 ) Decrease/ (increase) in equipment payable, net (838,740 ) 89,820 1,252,493 (Increase)/ decrease in notes payable of construction 699,900 — — Effect of foreign currency exchange (10,919 ) (63,997 ) (25,486 ) Cash payment for acquisition of property, plant, and equipment 13,855,431 15,295,121 12,932,655 B. Reconciliation of liabilities arising from financing activities: Non-Cash Charges As of January 1, 2017 Cash flows Foreign Fair Value Amortization Amortization As of December 31, 2017 NT$ NT$ NT$ NT$ NT$ NT$ NT$ Long-term loans (include the current portion) 18,340,747 (2,413,112 ) (89,221 ) — — 1,586 15,840,000 Short-term loans 2,741,250 912,080 (230,930 ) — — — 3,422,400 Convertible bonds (include the current portion) 12,712,651 — (987,093 ) — 289,671 — 12,015,229 Refundable deposits 38,907 21,749 (157 ) — — — 60,499 Total liabilities from financing activities 33,833,555 (1,479,283 ) (1,307,401 ) — 289,671 1,586 31,338,128 Financial liability at fair value through profit or loss 773,908 — — 35,732 — — 809,640 C. Non-cash investing activities: (1) As mentioned in Note 10(C), as a result of the merger between ChipMOS Technologies Inc., and ChipMOS Technologies (Bermuda) Ltd., shareholders of ChipMOS Technologies (Bermuda) Ltd. received US$3.71 dollars in cash and 0.9355 share of American Depository Shares (“ADS”) in exchange for each share in ChipMOS Technologies (Bermuda) Ltd. Each ADS represents 20 new common shares issued by ChipMOS Technologies Inc. For the year ended NT$ Available-for-sale financial assets, non-current - ADS of ChipMOS Technologies Inc. 655,066 Available-for-sale financial assets, non-current - ChipMOS Technologies (Bermuda) Ltd. : Decrease in available-for-sale financial assets, non-current (748,540 ) Other income (51,923 ) Increase in other receivables 145,397 — (2) As mentioned in Note 11(C), Interconnect made a capital reduction in December 2015. The 39% interests in AAPM were distributed to the Company as capital return. For the year ended NT$ Acquisition of investments accounted for using the equity method-AAPM 137,011 Disposal of Associate-Interconnect: Decrease in difference on translation (Show as other equity item) 3,291 Decrease in deferred tax liabilities 674 Decrease in investments accounted for using the equity method (1,409 ) Gains on disposal of investments (139,567 ) —

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2017
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Operating Leases	30. Operating Leases The Company leases several parcels of land from the Science Park Administration with expiration dates between December 2023 and December 2034. The Company can renew the leases upon expiration. The Company also entered into lease agreements for its buildings and certain machinery and equipment. Besides, Siliconware Technology (Suzhou) Limited entered into lease agreements for its land use right and certain machinery and equipment. Siliconware Electronics (Fujian) Co., Limited also entered into lease agreements for its land use right. For the years ended December 31, 2015, 2016 and 2017, the Group recognized rental expense amounted to $490,132, $662,839 and $730,047, respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
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Related Party Transactions	31. Related Party Transactions Inter-company transactions and balance on transactions between group companies are eliminated when preparing this consolidated financial statement and are not disclosed in this footnote. The transactions between the Group and other related parties are as follows: A. Disposal of Financial Assets For the year ended December 31, 2016 Financial Statement Account Shares Marketable Securities Type and Name Disposal of Gain on NT$ NT$ Associates Available-for-sale financial 57,810 Hsieh Yong Capital Co., Ltd. (Stock) 376,943 206,943 There is no such transaction in 2017. B. On June 30, 2016, the Company’s Board of Directors has adopted resolution to approve the entering into and execution of a “joint share exchange agreement” (the “Agreement”) with Advanced Semiconductor Engineering, Inc. ( the “ASE”) and agrees to establish a new holding company (the “HoldCo”). The collaboration between the parties will result in synergies that can create a competitive advantages and opportunities for the future development and sustained growth of the semiconductor industry by enhancing efficiency and economies of scale as well deeply strengthening research and development and innovation capabilities, thereby providing customers with higher quality, more efficient, and well-rounded packaging and testing services. The Agreement will be conducted (1) at an exchange ratio of one ASE common share for 0.5 HoldCo common share, and (2) at NT$55 dollars in cash for each of SPIL’s common shares (after earning distribution in 2016, has been adjusted to NT$51.2 dollars), with ASE and SPIL becoming wholly-owned subsidiaries of HoldCo. C. The closing of the transaction will be subject to the necessary approvals by relevant domestic and foreign competent authorities. On November 16, 2016, the Taiwan Fair Committee has decided not to prohibit the merger transactions between the ASE and SPIL, and on May 15, 2017, the Company received an official confirmation letter from the US Federal Trade Commission (FTC) stating that the non-public investigation procedure has been closed. On November 24, 2017, the Anti-Monopoly Bureau under the Ministry of Commerce of the PRC (“MOFCOM”) approved the proposed combination on the following four conditions, among others: 1. HoldCo should maintain the legal personality of ASE and SPIL as independent competitors for a period of 24 months (“Restriction Period”). 2. During the Restriction Period, HoldCo will only exercise limited shareholder rights. Such limitation includes: other than the right to obtain dividend related and financial information from ASE and SPIL, HoldCo should temporarily cease to exercise its other shareholder’s rights. 3. During the Restriction Period, ASE and SPIL each covenants to provide services to customers on a non-discriminatory basis, and set service price and related transactional terms according to AML, reasonable commercial consideration and normal business operation. 4. During the Restriction Period, ASE and SPIL each convents to not limit the customers’ choice of alternative suppliers of semiconductor packaging and testing businesses, and will cooperate with customers for requests related to switching such suppliers, under the circumstance that the customers obey the laws and regulations, and do not involves tort and breaking contracts. All the conditions above are subject to further revisions in the official notice that may be published by MOFCOM from time to time. An extraordinary general meeting has been convened on February 12, 2018 and approved the HoldCo to acquire all issued shares of both companies. The issued shares of the Company and ASE shall be delisted on the share exchange record date after all procedures of the Share Exchange Transactions are completed then the HoldCo’s share shall be listed in Taiwan and United States Stock Market Exchange. The Company and ASE will maintain their respective existence, name and the independent operation and business model of their current and future business. The establishment of HoldCo will be completed by the end of April 2018. This timeline, however, is subject to the review progress of competent authorities. D. The long stop date of the Agreement (the “Long Stop Date”), which means the expiration of the Agreement, was set at 18 months after the execution date of the Agreement (i.e., December 31, 2017). On December 14, 2017, the Company and ASE entered into a Supplemental Agreement to Joint Share Exchange Agreement to amend the definition of Long Stop Date as October 31, 2018 or a later date otherwise agreed in writing by the Company and ASE. E. Personnel compensations to Directors and Managements For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Short-term employee benefits 370,943 443,802 313,922 Post-employment benefits 2,866 65,217 2,991 373,809 509,019 316,913

Assets Pledged as Collateral

Assets Pledged as Collateral	12 Months Ended
	Dec. 31, 2017
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Assets Pledged as Collateral	32. Assets Pledged as Collateral The following assets have been pledged as collateral against certain obligations of the Company: As of December 31, Assets 2016 2017 Subject of collateral NT$ NT$ Time deposits (shown as other current assets - other) 357,400 392,100 Guarantees for customs duties and land leased from Science Park Administration

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
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Commitments and Contingencies	33. Commitments and Contingencies A. According to the Agreement between the Company and ASE , if any of the events described below occurs during the period from the Execution Date until the Share Exchange Record Date, except the prior written consent of ASE, the Company shall not, nor induce the Company’s subsidiaries to conduct the followings: (1) Issue any equity-linked securities (except for any share(s) newly issued as a result of the exercise of conversion rights by holders of the Company’s Foreign Convertible Bonds). (2) Except for the repurchase of shares from the shareholders exercising appraisal rights in connection with this Transaction in accordance with laws and regulations and Article 13 hereof or redemption of the Company’s Foreign Convertible Bonds as contractually agreed, directly or indirectly repurchase, individually or through any third party, its issued and outstanding shares or equity-linked securities, decrease capital, resolve for dissolution, or file for restructuring, settlement or bankruptcy. (3) Except subject to affirmative court judgments, arbitration awards or approvals, orders, administrative decisions or approved conditions/burdens or other requirements imposed by competent authorities (including, but not limited to, the Taiwan Stock Exchange, the Taiwan Fair Trade Commission, the United States Federal Trade Commission, the SEC, and the Antitrust Law Enforcement Authorities of Relevant Countries and Regions), none of the Company or any of its directors, managers, employees, agents or representatives may offer, agree, enter into or sign with any third party any contract, agreement or other arrangements in respect of any following matter: (a) any transaction that may involve a spin-off, a purchase or a sale of shares of non-financial investment nature, or any other transaction of similar nature; (b) a lease of all businesses or an entrustment, a joint operation, or an assumption of the entire business or assets from others (except for an assumption of the entire business or assets from others in an aggregated transaction amount less than NT$0.5 billion); or (c) any merger and acquisition without issuing HoldCo’s shares, any sale of all or material assets or businesses of 100% owned subsidiaries, any disposal of interest in material assets or businesses of 100% owned subsidiaries, or exclusive licensing of all or material patents or technologies of 100% owned subsidiaries, provided. However, if the Company receives a Superior Proposal from a third party the conditions of which are more favorable than those of this Transaction that cannot complete the Share Exchange under this Agreement due to its acceptance of a Superior Proposal as set forth above, the Company shall pay to ASE the amount of NT$17 billion as a termination fee for the Transaction. B. For the needs of future operation expansion, the Group entered into several significant agreements amounting to $1,454,580, of which $144,908 remained unpaid as of December 31, 2017. C. Future minimum lease payments under the non-cancellable operating leases are as follows: As of December 31, 2017 NT$ Within 1 year 143,573 1-5 year(s) 298,888 Over 5 years 657,830 1,100,291

Significant Event After the Rep

Significant Event After the Reporting Period	12 Months Ended
	Dec. 31, 2017
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Significant Event After the Reporting Period	34. Significant Event After the Reporting Period A. The Company convened an extraordinary general meeting on February 12, 2018 to resolve the Joint Share Exchange Agreement, Supplemental Agreement to Joint Share Exchange Agreement and the transaction completed by the Joint Share Exchange Agreement with Advanced Semiconductor Engineering, Inc. On the same day, the Board of Directors resolved April 30, 2018 as the effective date of the Share Exchange Transactions and the delisting date of the Company’s shares. B. In order to participate in the prime period of growth for the mainland China semiconductor market, the Company forms a strategic alliance to expand the China market, and will use the proceeds of disposal on the investment of Taiwan headquarter. On November 24, 2017 SPIL (Cayman) Holding Limited, a subsidiary of SPIL, entered into an agreement with Tsinghua Unigroup Ltd. to dispose 30% shares of Siliconware Technology (Suzhou) Ltd. to Tsinghua Unigroup Ltd. The transaction was completed in February 2018 with total transaction amount of $4,675,542 (RMB 1,026,000 thousand). Since the transaction did not cease the control over Siliconware Technology (Suzhou) Ltd., the above transaction was accounted as an equity transaction. C. Under the amendment Income Tax Law passed in February 2018, effective from 2018, the corporate income tax rate has been adjusted from 17% to 20% and the undistributed earnings rate has been adjusted from 10% to 5%. There is no significant impact on the 2017 consolidated financial statements.

Financial Risk Management

Financial Risk Management	12 Months Ended
	Dec. 31, 2017
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Financial Risk Management	35. Financial Risk Management The Group’s activities expose it to a variety of financial risk: market risk (including currency risk, price risk, and interest rate risk), credit risk and liquidity risk. The Group’s overall risk management program focuses on the unpredictability of financial markets and seeks to minimize potential adverse effects on the Group’s financial performance. A. Market risk (1) Currency risk The Group operates internationally and is exposed to foreign exchange risk arising from various currency exposures, primarily with respect to the USD and the JPY. Foreign exchange risk arises from future commercial transactions, recognized assets and liabilities and net investments in foreign operations. The Group implements the policy of natural hedging and monitors the foreign exchange rate fluctuation closely to manage the risk. The Group’s exposure to foreign exchange risk is as follows: As of December 31, 2016 (Foreign currencies: functional currencies) Sensitivity analysis Foreign Exchange Movement Impact to (NT$) Financial assets Monetary assets USD:NTD 800,272 32.200 1 % 257,688 USD:RMB 17,786 6.9370 1 % 5,727 Nonmonetary assets USD:NTD 21,951 32.200 N/A N/A Investments accounted for using the equity method USD:NTD 559 32.250 N/A N/A Financial Liabilities Monetary liabilities USD:NTD 596,659 32.300 1 % 192,721 USD:RMB 113,280 6.9370 1 % 36,589 JPY:NTD 3,838,753 0.2776 1 % 10,656 JPY:RMB 596,668 0.0596 1 % 1,656 As of December 31, 2017 (Foreign currencies: functional currencies) Sensitivity analysis Foreign Exchange Movement Impact to (NT$) Financial assets Monetary assets USD:NTD 588,521 29.710 1 % 174,850 USD:RMB 43,141 6.5342 1 % 12,817 Financial Liabilities Monetary liabilities USD:NTD 550,842 29.810 1 % 164,206 USD:RMB 158,166 6.5342 1 % 47,149 JPY:NTD 2,912,882 0.2662 1 % 7,754 JPY:RMB 1,013,068 0.0579 1 % 2,697 Note: Currency risk does not arise from financial instruments that are nonmonetary items and thus are not subject to sensitivity analysis. (2) Price risk Pursuant to strategic investments objective, the Group exposed to equity securities price risk in public market because of investments held by the Group are classified as available-for-sale financial assets. To manage the market price risk, the Group monitors the future development of the investees and the market trend. Most investees of the Company are in electronic industry, of which ChipMOS Technologies Inc. is traded publicly in the market. ChipMOS Technologies Inc.’s shares are listed on Taiwan Stock Exchange and the ADS of ChipMOS Technologies Inc. are listed on NASDAQ. For other equity investees that are not traded in public market, the Group implements suitable techniques to perform the assessments. As of December 31, 2016 and 2017, if the market price had increased/decreased by 10% with all other variables held constant, other comprehensive income would have increased/decreased by $352,579 and $413,521, respectively. (3) Interest rate risk The Group’s interest rate risk arises from cash, interest bearing time deposits, and borrowings. Mostly, residual cash will be held as deposit. For the fixed rate of time deposits, the change of interest rate will have no impact on future cash flow. As of December 31, 2016 and 2017, the Group held financial assets with cash flow interest rate risk of $6,092 and $0, respectively, and financial liabilities with cash flow interest rate risk of $21,083,583 and $19,262,400, respectively. For the years ended December 31, 2016 and 2017, if the interest rate had been increased/ decreased by 10 points (0.1%), income before income tax for the period would have been decreased by $21,077 and increased by $19,262 lower / higher, respectively. B. Credit risk The Group’s credit risk mainly arises from cash and cash equivalents (deposits with banks or financial institutions), accounts and notes receivable, refundable deposits and etc. (1) For risks from banks and financial institutions, the Group periodically assesses their credit ratings based on information provided by external independent rating institutes. Furthermore, to minimize the credit risk, the Group allocates deposits based on each bank’s rating results. After the assessment, most of banks and financial institutions the Group transacts with are with minimum rating of “A”, which represents low credit default risks. (2) For risks from accounts and notes receivable, the Group assesses customers’ credit quality through internal risk assessment, taking into account of their current financial conditions and past transaction experiences. After the assessment, management does not expect significant losses from non-performance by these counterparties. (3) Aging analysis of accounts receivables that were past due is as follows: As of December 31, 2016 Total Impaired Unimpaired NT$ NT$ NT$ 1-90 days 933,715 — 933,715 91-180 days 54,947 — 54,947 Over 180 days 5,401 1,695 3,706 994,063 1,695 992,368 As of December 31, 2017 Total Impaired Unimpaired NT$ NT$ NT$ 1-90 days 1,322,342 — 1,322,342 91-180 days 15,165 10,238 4,927 Over 180 days 3,561 1,695 1,866 1,341,068 11,933 1,329,135 Note: As of December 31, 2016 and 2017, no impairment loss incurred on accounts receivables that are not past due. (4) As of December 31, 2016 and 2017, the Group’s ten largest customers accounted for 65% and 67% of accounts receivables, respectively. The Group considers the concentration of credit risk for the remaining accounts receivable is immaterial. C. Liquidity risk The objective of liquidity risk management is to ensure the Group has sufficient liquidity to fund its business needs, and to maintain adequate cash, banking facilities to repay the borrowings. By considering its debt financing plans, covenant compliance, compliance with internal balance sheet ratio targets, and other important factors, the finance department of the Company monitors the Group cash requirements and forecasts its future cash flow. The table below summarizes the maturity profile of the Group’s financial liabilities based on contractual terms (including principals and interests payments), which is presented on an undiscounted basis: As of December 31, 2016 Less than 1 year 1-2 years 2-3 years Over 3 years Total NT$ NT$ NT$ NT$ NT$ Short-term Loans 2,761,041 — — — 2,761,041 Accounts Payable 8,194,647 — — — 8,194,647 Other Payables 11,896,517 — — — 11,896,517 Other Current Liabilities-Others 106,859 — — — 106,859 Convertible Bonds (include the current portion) 13,312,768 — — — 13,312,768 Long-term Loans (include the current portion) 3,714,850 2,851,419 5,959,549 6,402,421 18,928,239 Other Non-Current Liabilities — 63,215 — 8,279 71,494 39,986,682 2,914,634 5,959,549 6,410,700 55,271,565 As of December 31, 2017 Less than 1 1-2 years 2-3 years Over 3 Total NT$ NT$ NT$ NT$ NT$ Short-term Loans 3,454,355 — — — 3,454,355 Accounts Payable 7,456,974 — — — 7,456,974 Other Payables 10,082,704 — — — 10,082,704 Other Current Liabilities-Others 133,212 — — — 133,212 Convertible Bonds (include the current portion) — 12,533,316 — — 12,533,316 Long-term Loans (include the current portion) 3,363,170 6,462,779 3,889,463 2,513,314 16,228,726 Other Non-Current Liabilities — 5,052 208 1,228 6,488 24,490,415 19,001,147 3,889,671 2,514,542 49,895,775

Capital Risk Management

Capital Risk Management	12 Months Ended
	Dec. 31, 2017
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Capital Risk Management	36. Capital Risk Management A. The capital includes common share, capital reserve, legal reserve, and other equity items. The Group’s objectives in managing capital are to maintain sufficient capital to expand production capacity and equipment, and ensure the Group has sufficient and necessary financial resources to deal with operating capital demand, capital expenditure, research and development expenditure, dividend expenditure, loan repayment, and other operating demand. B. Except for those mentioned in Note 18, the Company does not have to follow any restrictions of outside capital.

Fair Value Information on Finan

Fair Value Information on Financial Instruments	12 Months Ended
	Dec. 31, 2017
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Fair Value Information on Financial Instruments	37. Fair Value Information on Financial Instruments A. Fair value of financial instruments not carried at fair value Except for convertible bonds which are measured at amortized cost, the management considers that the carrying amounts of financial assets and financial liabilities recognized in the consolidated financial statements approximate to their fair values. The fair value of the Group’s short-term financial instruments including cash and cash equivalents, receivables, time deposits, short-term loans, current portion of long-term loans, payables, receipts under custody and deposits received approximated their carrying amount due to their maturities within one year. The Group’s non-current financial instruments including non-interest bearing refundable deposits, receipts under custody, bank loans carried at floating interest rates and long-term payables. The fair value of these financial instruments are approximated to its carrying amount due to the impact of discounting is not significant, or because the floating interest rates reset periodically to reflect the market conditions and the Group’s credit rating. As of December 31, 2016 and 2017, the book value and fair value of the convertible bonds (include the current portion) are as follow: Carrying Amount Fair Value (Level 3) NT$ NT$ December 31, 2016 12,712,651 12,841,188 December 31, 2017 12,015,229 12,007,468 The fair value was determined using discounted cash flow analysis with the applicable yield curve for the duration and recent transaction prices. B. The table below analyses financial instruments carried at fair value by valuation method. The different levels have been defined as follows: Level 1: Quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2: Inputs other than quoted prices included within level 1 that are observable for the asset or liability, either directly or indirectly. Level 3: Inputs for the asset or liability that are not based on observable market data. C. The Company’s financial instruments measured at fair value are as follows: Recurring basis As of December 31, 2016 Level 1 Level 2 Level 3 NT$ NT$ NT$ Available-for-sale financial assets 3,615,658 178,176 — Financial liability at fair value through profit or loss — — 773,908 As of December 31, 2017 Level 1 Level 2 Level 3 NT$ NT$ NT$ Available-for-sale financial assets 4,135,207 — — Financial liability at fair value through profit or loss — — 809,640 Non-recurring basis None. (1) The fair value of financial instruments traded in active markets is based on quoted market price at the balance sheet date. For financial instruments with fair value not traded in active markets, the Company uses valuation techniques, which maximize the use of observable market data where it is available and relies as little as possible on entity specific estimates. The valuation technique currently used for unlisted available-for-sale securities is the market approach. The valuation is based on the benchmark companies’ stock prices and other specific indexes. If all significant inputs required to fair value an instrument are observable, the instrument is included in level 2. If one or more of the significant inputs is not based on observable market data, the instrument is included in Level 3. Specific valuation techniques used to value financial instruments include: A. Quoted market prices or dealer quotes for similar instruments; B. Other techniques, such as discounted cash flow analysis, are used to determine fair value for the remaining financial instruments. (2) There were no transfers between Level 1 and 2 for the years ended December 31, 2016 and 2017. (3) The fair value measurements for the Company’s derivative instruments are carried out on the basis of a binomial model, with measurement on a quarterly basis. In the course of the valuation process, the required market data are collected and the non-observable parameters are examined and updated as required on the basis of internally available current information. In particular, the premises of the enterprise value of the Company’s derivative instruments, as well as any significant changes in the input parameters and their respective effects on the value of the option, are reported to management on a quarterly basis. (4) Parameters with a significant influence on the measurement of the option are the value of the Company’s derivative instruments as determined with the use of a discounted cash flow method and the expected volatility of that value. The approach for volatility estimation was changed to a direct analysis of the historical volatility. The higher the volatility, the fair value of the Company’s derivative instrument will be higher. The volatility as of December 31, 2016 and 2017 is 26.83% and 9.72%, respectively. (5) Reconciliation of Level 3 fair value measurements of financial liabilities 2015 2016 2017 NT$ NT$ NT$ As of January 1 1,095,552 1,798,920 773,908 Losses (Gains) recognized in profit or loss 703,368 (1,025,012 ) 35,732 As of December 31 1,798,920 773,908 809,640 The total gains or losses for the years ended December 31, 2015, 2016 and 2017 included loss of $703,368, gain of $1,025,012 and loss of $35,732, respectively, relating to the financial liabilities at fair value on Level 3 fair value measurement and held at balance sheet date. (6) The Company has carefully assessed the valuation models and assumptions used to measure fair value. However, using different valuation models or assumptions may result in difference in fair value measurement. For financial assets and liabilities categorized within Level 3, a 10% increase in the value of stock market price would lead to a decrease in income before tax by $662,796 and $1,172,129 for the years ended December 31, 2016 and 2017, respectively. On the other hand, a 10% decrease in the value of the stock market price would increase income before tax by $549,100 and $808,447 for the years ended December 31, 2016 and 2017, respectively. A 5% increase in the expected volatility of the value of the derivative instrument would lead to a decrease in income before tax by $258,400 and $184,822 for the years ended December 31, 2016 and 2017, respectively. A 5% decrease in the expected volatility of the value of derivative instrument would increase income before tax by $276,488 and $106,124, for the years ended December 31, 2016 and 2017, respectively.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
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Segment Information	38. Segment Information The Group’s packaging and testing services are provided in Taiwan and China. The chief operating decision maker determines the group’s performance based on the geographic perspective. The nature of services, production process, type of customers and service delivery model at these two geographical locations are similar. While the chief operating decision maker receives separate reports for each location, these two operating segments have been aggregated into one reportable segment as they have similar long-term average gross margins and have similar economic characteristics. As a result, the Group discloses a single reporting segment. The Group uses the income from operations as the measurement for segment profit and the basis of performance assessment which is consistent with the basis of preparation of the financial statements. A. Breakdown of the revenue from different products and services: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Packaging 72,752,428 74,315,486 70,851,943 Testing 9,551,025 10,227,996 11,983,667 Others 536,469 568,431 718,775 82,839,922 85,111,913 83,554,385 B. Operations in different geographic areas: Revenues are summarized by the areas where our customers’ group headquarters locate. In prior years, this information was summarized based on the location of customers’ regional headquarters. Non-current assets, including equity method investment, property, plant and equipment, refundable deposits, and other assets, but not including financial instruments and deferred income tax assets, are categorized by their locations. For the Years Ended December 31, 2015 2016 2017 Revenues Noncurrent Assets Revenues Noncurrent Assets Revenues Noncurrent Assets NT$ NT$ NT$ NT$ NT$ NT$ United States 30,076,050 1,553 33,624,139 1,728 32,018,540 1,739 China 21,318,660 8,068,694 22,724,680 9,014,191 24,778,540 11,803,140 Taiwan 18,106,693 59,606,745 19,683,484 59,371,230 15,494,157 54,572,997 Europe 8,470,707 — 6,794,827 — 8,315,142 — Others 4,867,812 122,748 2,284,783 18,019 2,948,006 — 82,839,922 67,799,740 85,111,913 68,405,168 83,554,385 66,377,876 C. Major Customers: In 2015, 2016 and 2017, operating revenues of $15,096,281, $15,979,382 and $17,091,540 were from customer A, respectively, and the operating revenues of $10,053,063, $11,794,072 and $8,405,084 were from customer B, respectively.

Valuation and Qualifying Accoun

Valuation and Qualifying Account	12 Months Ended
	Dec. 31, 2017
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Valuation and Qualifying Account	39. Valuation and Qualifying Account Description Balance at Additions Deductions Exchange Balance NT$ NT$ NT$ NT$ NT$ For the year ended 2015 Allowance for doubtful accounts 1,695 — — — 1,695 Allowance for sales discounts 275,705 152,224 413,668 (205 ) 14,056 Allowance for loss on obsolescence and decline in market value of inventory 143,348 20,480 — (772 ) 163,056 Allowance for loss on idle assets 93,361 64,996 45,220 (580 ) 112,557 For the year ended 2016 Allowance for doubtful accounts 1,695 — — — 1,695 Allowance for sales discounts 14,056 — 11,050 — 3,006 Allowance for loss on obsolescence and decline in market value of inventory 163,056 112,374 — (3,978 ) 271,452 Allowance for loss on idle assets 112,557 91,247 76,822 (1,623 ) 125,359 For the year ended 2017 Allowance for doubtful accounts 1,695 11,911 1,673 — 11,933 Allowance for sales discounts 3,006 — 3,006 — — Allowance for loss on obsolescence and decline in market value of inventory 271,452 69,869 — (935 ) 340,386 Allowance for loss on idle assets 125,359 88,231 97,961 (489 ) 115,140

Summary of Significant Accoun45

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
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Basis of Preparation	(1) Basis of Preparation A. Compliance with IFRS The consolidated financial statements have been prepared in accordance with International Financial Reporting Standards and the interpretations of the IFRS interpretations committee (“IFRIC”). The accompanying consolidated financial statements are prepared in conformity with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). B. Historical cost convention The consolidated financial statements have been prepared on a historical cost basis, except for the following: • available-for-sale financial assets, financial assets and liabilities (including derivative instruments)—measured at fair value • defined benefit pension plans - net amount of pension fund assets less present value of defined benefit obligation measured at fair value. The preparation requires the use of certain critical accounting estimates and also requires management to exercise its judgement in the process of applying the accounting policies. The areas involving a higher degree of judgement or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are disclosed in Note 5.
Principles of Consolidation	(2) Principles of Consolidation Pursuant to IFRS 10, “Consolidated financial statements”, subsidiaries are those entities controlled by the Company or its subsidiaries. The Company controls an entity when the Company is exposed to, or has right to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Company. They are deconsolidated from the date that control ceases. Inter-company transactions, balances and unrealized gains on transactions between group companies are eliminated. Unrealized losses are also eliminated. Accounting policies of subsidiaries have been changed where necessary to ensure consistency with the policies adopted by the Group. Consolidated subsidiaries: % of ownership held by the named Name of investor Name of subsidiaries Main operating activities 2016 2017 The Company SPIL (B.V.I.) Holding Limited Investment activities 100 % 100 % The Company Siliconware Investment Co., Ltd. Investment activities 100 % 100 % SPIL (B.V.I.) Holding Limited Siliconware USA, Inc. (SUI) Communications and relationship maintenance with companies headquartered in North America 100 % 100 % SPIL (B.V.I.) Holding Limited SPIL (Cayman) Holding Limited Investment activities 100 % 100 % SPIL (Cayman) Holding Limited Siliconware Technology (Suzhou) Limited Assembly and testing services 100 % 100 % SPIL (Cayman) Holding Limited Siliconware Electronics (Fujian) Co., Limited (1) Assembly and testing services — 100 % (1) Siliconware Electronics (Fujian) Co., Limited was established in July 2017 and mainly engaged in assembly and testing service for memory and logic devices with initial capital of US$45,000 thousands.
Segment Reporting	(3) Segment Reporting Operating segments are reported in a manner consistent with the internal reporting provided to the chief operating decision maker. The chief operating decision maker assesses performance and allocates resources based on the economic environment. All of the Company’s segments have similar economic characteristics and meet the criteria of aggreggation. As a result, the Company discloses a single reporting segment by aggregating all the operating segments.
Foreign Currency Translation	(4) Foreign Currency Translation A. Convenience Translation into US Dollars The Group maintains its accounting records and prepares its financial statements in New Taiwan (“NT”) dollars. The United States (“US”) dollar amounts disclosed in the 2017 financial statements are presented solely for the convenience of the reader and were translated at the rate of NT$29.64 (in dollars) to US$1.00 (in dollars), which was the noon buying rate as certified for customs purposes by the Federal Reserve Bank of New York on December 29, 2017 as the last quoted rate at the balance sheet date. Such translation amounts are unaudited and should not be construed that the NT dollar amounts represent, or have been, or could be, converted into US dollars at that or any other rate. B. Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in New Taiwan Dollar (“NTD”), which is the presentation currency of the Group and the functional currency of the Company. C. Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions where items are re-measured. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies are recognized as other gains and losses in the statement of comprehensive income. D. Translation differences on non-monetary financial assets and liabilities such as equities held at fair value through profit or loss are recognized in profit or loss as part of the fair value gain or loss. Translation differences on non-monetary financial assets, such as equities classified as available-for-sale, are included in other comprehensive income. However, non-monetary assets and liabilities denominated in foreign currencies that are not measured at fair value are translated using the historical exchange rates at the dates of the initial transactions. E. The results and financial position of the Group entities that have a functional currency different from the presentation currency are translated into the presentation currency. Assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet, income and expenses for each statement of comprehensive income are translated at average exchange rates (unless this average is not a reasonable approximation of the cumulative effect of the rates prevailing on the transaction dates, in which case income and expenses are translated at the rate on the dates of the transactions), and all resulting exchange differences are recognized in other comprehensive income. Those differences would be recorded as gain or loss of disposal of investments in statement of comprehensive income if disposed.
Classification of Current and Noncurrent Assets / Liabilities	(5) Classification of Current and Noncurrent Assets / Liabilities A. Assets that meet one of the following criteria are classified as current assets; otherwise they are classified as noncurrent assets: (a) Assets arising from operating activities that are expected to be realized or consumed, or are intended to be sold within the normal operation cycle; (b) Assets held mainly for trading purposes; (c) Assets expected to be realized within twelve months from the balance sheet date; (d) Cash or cash equivalents, excluding restricted cash and cash equivalents and those that are to be exchanged or used to pay off liabilities more than twelve months after the balance sheet date. B. Liabilities that meet one of the following criteria are classified as current liabilities; otherwise they are classified as noncurrent liabilities: (a) Liabilities arising from operating activities that are expected to be paid off within the normal operating cycle; (b) Liabilities arising mainly from trading activities; (c) Liabilities that are to be paid off within twelve months from the balance sheet date; (d) Liabilities for which the repayment date cannot be extended unconditionally to more than twelve months after the balance sheet date.
Cash and Cash Equivalents	(6) Cash and Cash Equivalents Cash and cash equivalents include cash on hand, deposits held at call with banks, time deposits that meet operating short-term cash commitments and that are readily convertible to known amounts of cash and are subject to an insignificant risk of changes in value, and other short-term highly liquid investments.
Accounts Receivable	(7) Accounts Receivable Accounts receivable is recognized initially at fair value and subsequently measured at amortized cost using the effective interest method, less provision for impairment. Accounts receivable expected to be collected over one year is recorded at present value by using predetermined interest rate whereas those expected to be collected within one year are not reported at present value due to the fact that the difference between the maturity value and the fair value discounted by implicit interest rate is immaterial and the frequency of transactions is high.
Inventories	(8) Inventories Inventories are recorded at cost when acquired under a perpetual inventory system. Cost is determined using the weighted-average method. The cost of work in process comprises raw materials, direct labor, other direct costs and related production overheads based on normal operting capacity. As of the balance sheet date, inventories are stated at the lower of cost or net realizable value by item, except where it may be appropriate to similar groups or related items. Net realizable value is the estimated selling price in the ordinary course of business less all estimated costs of completion and necessary selling expenses. In the service agreements with and/or purchase orders from customers, the Group and the customer both agree what materials are to be provided by the customer and what materials are to be provided by the Group. Materials provided by the customers are considered consigned materials. According to the service agreement and/or purchase order, title (ownership) of the consigned materials belongs to the customers. The Group does not take title to these consigned materials. The Group does not have any rights or obligations with respect to the consigned materials other than keeping them in good care while under the Group’s custody, and therefore the risk does not transfer to the Group. In addition, the customers are informed of the status and locations of integrated circuits being assembled and/or tested by the Group which provides further evidence that the customers are taking control or monitoring those consigned materials. As such, the Group does not book the consigned materials into its inventory account.
Non-current Assets Held for Sale	(9) Non-current Assets Held for Sale Non-current assets are classified as held for sale if their carrying amount will be recovered principally through a sale transaction rather than through continuing use. This condition is regarded as met only when the sale is highly probable and the non-current asset held for sale is available for immediate sale in its present condition. To meet the criteria for the sale being highly probable, the appropriate level of management must be committed to the sale, which should be expected to qualify for recognition as a completed sale within one year from the date of classification. Non-current assets classified as held for sale are measured at the lower of their previous carrying amount and fair value less costs to sell. Recognition of depreciation would cease.
Financial Assets	(10) Financial Assets A. Classification The classification depends on the nature and purpose of acquiring the financial assets and the classification is determined at the time of initial recognition. (a) Loans and receivables Loans and receivables are non-derivative financial assets with fixed or determinable payments that are not quoted in an active market. (b) Available-for-sale financial assets Available-for-sale financial assets are non-derivative financial assets that are either designated in this category or not classified in any of the other categories. Except for those that are expected to be disposed more than one year after the end of the reporting period, which are classified as non-current assets, otherwise, they are classified as current assets. B. Recognition and Measurement (a) Regular purchases and sales of financial assets are recognized on the trade date (the date on which the Group commits to purchase or sell the asset). Financial assets carried at fair value through profit or loss are initially recognized at fair value, and transaction costs are expensed in the statement of comprehensive income. Other financial assets not carried at fair value through profit or losses are initially recognized at fair value plus transaction costs. Financial assets are derecognized when the rights to receive cash flows from the investments have expired or have been transferred and the Group has transferred substantially all risks and rewards of ownership. (b) Financial assets at fair value through profit or loss and available-for-sale financial assets are subsequently carried at fair value. Gains or losses arising from changes in the fair value of the “financial assets at fair value through profit or loss” category are presented in the statement of comprehensive income within “other gains and losses” in the period in which they arise. Changes in the fair value of securities classified as available-for-sale are recognized in other comprehensive income. Dividend income from these two assets is recognized in the statement of comprehensive income when the Group’s right to receive payments is established. (c) Loans and receivables are subsequently carried at amortized cost using the effective interest method. The interest arising subsequently is recognized in “interest income” in the statement of comprehensive income. (d) When securities classified as available-for-sale are sold or impaired, the accumulated fair value adjustments recognized in equity are included in the statement of comprehensive income as “gains and losses from investment securities” and “impairment losses”, respectively. C. Offsetting financial instruments Financial assets and liabilities are offset and the net amount reported in the balance sheet when there is a legally enforceable right to offset the recognized amounts and there is an intention to settle on a net basis or realize the asset and settle the liability simultaneously. The legally enforceable right must not be contingent on future events and must be enforceable in the normal course of business and in the event of default, insolvency or bankruptcy of the company or the counterparty.
Impairment of Financial Assets	(11) Impairment of Financial Assets A. Loans and receivables (a) The Group assesses at the end of each reporting period whether there is objective evidence that a financial asset or group of financial assets is impaired. A financial asset or a group of financial asset is impaired and impairment losses are incurred only if: i. There is objective evidence of impairment as a result of one or more events that occurred after initial recognition of the asset (a “loss event”), and ii. That loss event has an impact on the estimated future cash flows of the financial asset or group of financial assets that can be reliably estimated. Evidence of impairment includes: i. The debtor or the issuer is experiencing significant financial difficulty; ii. Default or delinquency in interest or principal payment; iii. Concessions made to the insolvent debtor by creditors owing to economic or legal considerations; iv. The probability that the debtor or debtors will enter bankruptcy or other financial reorganization; v. The disappearance of an active market for that financial asset because of financial difficulties; vi. Where observable data indicates that there is a measurable decrease in the estimated future cash flow, such as: • The repayment condition of the debtor to the Group of assets deteriorated • Changes in areas or economic conditions that correlate with defaults (b) The Group first assesses whether objective evidence of impairment exists individually for financial assets that are individually significant, and individually or collectively for financial assets that are not individually significant. If the Group determines that no objective evidence of impairment exists for an individually assessed financial asset, whether significant or not, it includes the asset in a group of financial assets with similar credit risk characteristics and collectively assesses them for impairment. For these assets, the amount of the loss is measured as the difference between the assets’ carrying amount and the present value of estimated future cash flows (excluding future credit losses that have not been incurred) discounted at the financial asset’s original effective interest rate. The carrying amount of the asset is reduced through the allowance account and the amount of the loss is recognized in the consolidated statement of comprehensive income. In a subsequent period, if the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized (such as an improvement in the debtor’s credit rating), the reversal of the previously recognized impairment loss is recognized in the consolidated statement of comprehensive income. B. Available-for-sale assets The Group assesses at the end of each reporting period whether there is objective evidence that a financial asset or a group of financial assets is impaired. In the case of equity investments classified as available-for-sale, any significant unfavorable change that takes place in the technical, market, economic, or legal environments where the issuer operates indicates the possibility that the investment cost of the equity instrument may not be recovered and a significant or prolonged decline in the fair value of the security below its cost are evidences that the assets are impaired. If any such evidence exists for available-for-sale financial assets, the cumulative loss—measured as the difference between the acquisition cost and the current fair value, less any impairment loss on that financial asset previously recognized in profit or loss is removed from equity and recognized in profit or loss. Impairment losses recognized in the consolidated statement of comprehensive income on equity instruments are not reversed through the consolidated statement of comprehensive income in a subsequent period.
Equity Method Investments	(12) Equity Method Investments Investment in associate A. Associates, which are accounted for using the equity method of accounting, are all entities over which the Group has significant influence, which means the power to participate in the financial and operating policy decisions of the investees, but not control or joint control, generally accompanying a shareholding of between 20% and 50% of the voting rights. Under the equity method, the investment is initially recognized at cost, and the carrying amount is increased or decreased to recognize the investor’s share of the profit or loss of the investee after the date of acquisition. The Group’s investment in associates includes goodwill identified on acquisition. B. The Group’s share of post-acquisition profit or loss is recognized in the statement of comprehensive income, and its share of post-acquisition movements in other comprehensive income is recognized in other comprehensive income with a corresponding adjustment to the carrying amount of the investment. When the Group’s share of losses in an associate equals or exceeds its interest in the associate, including any other unsecured receivables, the Group does not recognize further losses, unless it has incurred legal or constructive obligations or made payments on behalf of the associate. C. If the ownership interest in an associate is reduced but significant influence is retained, only a proportionate share of the amounts previously recognized in other comprehensive income is reclassified to profit or loss where appropriate. Dilution gains and losses arising in investments in associates are recognized in the statement of comprehensive income. D. Profits and losses resulting from upstream and downstream transactions between the Group and its associates are recognized in the Group’s financial statements only to the extent of unrelated investor’s interests in the associates. Unrealized losses are eliminated unless the transaction provides evidence of an impairment of the asset transferred. Material accounting policy differences between associates and the Group were properly assessed and changed where necessary to ensure consistency with those adopted by the Group. E. The Group determines at each reporting date whether there is any objective evidence that the investment in the associate is impaired. If this is the case, the Group calculates the amount of impairment as the difference between the recoverable amount of the associate and its carrying value and recognizes the amount in the statement of comprehensive income.
Property, Plant and Equipment	(13) Property, Plant and Equipment A. Property, plant and equipment are stated at historical cost less accumulated depreciation and impairments. The acquisition costs include the purchase price, any costs directly attributable to bringing the asset to the location and condition necessary for it to be capable of operating, and the obligations to dismantle and remove the items and restore the site on which they are located. The subsequent costs will only be recognized under the conditions that future economic benefits associated with the item will flow to the Group and the item cost can be measured reliably. The carrying amount of the replaced part is derecognized. Day-to-day servicing costs and repairment expenditures are recognized as expenses as incurred. B. The Group capitalizes borrowing costs that are directly attributable to the acquisition, construction or production of a qualifying asset as part of the cost of that asset. The capitalized borrowing costs will be depreciated through the residual useful lives of related items. Borrowing costs which do not qualify for capitalization are recognized in profit or loss. C. If material part of replacing items of property, plant and equipment has different useful life from the main asset, it should be recognized and depreciated separately. Land is not depreciated. Depreciation on other assets is calculated using the straight-line method to allocate their cost to their residual values over their estimated useful lives. The estimated useful lives of property, plant and equipment are as follows: Property, plant and equipment Estimated useful lives Buildings - Main buildings 20-55 years - Construction and improvements 3-15 years Machinery and equipment 5-6 years Other equipment 2-6 years D. The assets’ residual values and useful lives are reviewed, and adjusted if appropriate, at the end of each fiscal year. Gains and losses on disposals are determined by comparing the proceeds with the carrying amount and are recognized within “Other income and expenses” in the statement of comprehensive income.
Intangible Assets	(14) Intangible Assets Intangible assets are the expenditures of license fees and computer software. License fees are capitalized at historical cost. Acquired computer software is capitalized on the basis of the costs incurred to acquire and bring to use the specific software. Both license fees and computer software are intangible assets with limited useful lives. They are subsequently measured at cost less accumulated amortization and impairment. Computer software is amortized over three years whereas license fees are amortized over their economic lives or the contract years using straight-line method or based on portions of sales. Subsequent measurements are measured using costs less accumulated amortization.
Impairment of Non-financial Assets	(15) Impairment of Non-financial Assets A. Intangible assets with definite useful life and other assets are tested for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. For the purposes of assessing impairment, assets are grouped at the lowest levels for which there are largely independent cash flows (cash-generating units). The recoverable amount is the higher of an asset’s fair value, defined as the price that would be received to dispose an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, less costs to dispose, or it’s value in use. The value in use is the present value of the future cash flows expected to be derived from an asset or cash-generating unit. B. An impairment loss recognized in prior periods for an asset shall be reversed if there has been a change in the estimates used to determine the asset’s recoverable amount since the last impairment loss was recognized. The carrying amount of the asset shall be reversed to its recoverable amount. The increased carrying amount of an asset attributable to a reversal of an impairment loss shall not exceed the carrying amount that would have been determined had no impairment loss been recognized for the asset in prior years.
Accounts Payable	(16) Accounts Payable Accounts payable are obligations to pay for goods or services that have been acquired in the ordinary course of business from suppliers. Accounts payable are recognized initially at fair value and subsequently measured at amortized cost using the effective interest method. Accounts payable of which payment due is within one year or less are not discounted while their fair value are close to the value in maturity and they are transacted actively.
Financial liabilities at fair value through profit or loss	(17) Financial liabilities at fair value through profit or loss A. Financial liability is classified in fair value through profit or loss while it is held for trading or identified at fair value through profit or loss on initial recognition. A financial liability is held for trading if it is acquired or incurred principally for the purpose of selling or repurchasing it in the near term, or if it is a derivative that is neither classified as a financial guarantee contract nor designated and effective as a hedging instrument. A financial liability is designated as at fair value through profit or loss upon initial recognition if: i. Such designation eliminates or significantly reduces a measurement or recognition in consistency that would otherwise arise; or ii. The financial liability forms part of a group of financial assets or financial liabilities or both, which is managed and its performance is evaluated on a fair value basis, in accordance with the Group’s documented risk management or investment strategy, and information about the grouping is provided internally on that basis; or iii. It forms part of a contract containing one or more embedded derivatives, and IAS 39 permits the entire combined contract to be designated as at fair value through profit or loss. B. Financial liabilities at fair value through profit or loss are stated at fair value upon initial recognition, and the related transaction cost are expensed immediately. In subsequent measurement, the Group measures fair value fluctuation in current profit or loss.
Convertible Bonds	(18) Convertible Bonds Convertible bonds issued by the Company contain liability, conversion option, redemption option and put option (collectively the “Bonds Options”) components. The Company assesses if the economic characteristics and risks of the redemption option and put embedded in the convertible bonds are closely related to the economic characteristics and risk of the host contract before separating the equity component. For the embedded derivative that is not closely related to the host contract, it is classified as a liability component and subsequently measured at fair value through profit or loss unless it qualifies as an equity component. The equity component is assigned the residual amount after deducting from the fair value of the instrument as a whole the amount separately determined for the liability component. Its carrying amount is not remeasured in the subsequent accounting periods. If the convertible bond issued does not have an equity component, it is accounted for as a hybrid instrument in accordance with the requirements under IAS 39. The conversion option 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 Company’s own equity instruments is classified as a conversion option derivative. At the date of offering, the Bonds Options components are classified as a derivative liability and subsequently measured at fair value through profit and loss. The liability component excluding the Bonds Options is measured at amortized cost using the effective interest method. Transaction costs that relate to the offering of the convertible bonds are allocated to the liability and the Bonds Options components in proportion to their relative fair values. Transaction costs relating to the Bonds Options are recognized immediately in profit or loss. Transaction costs relating to the liability component are included in the carrying amount of the liability component and amortized using the effective interest method. If the convertible bondholders exercise their conversion right before maturity, the Company shall adjust the carrying amount of the liability components. The adjusted carrying amounts of the liability components at conversion are credited to capital stock and capital reserve. In addition, the liability components of convertible bonds is classified as a current liability if within 12 months the bondholders may exercise the put right. After the put right expires, the liability component of the convertible bonds should be reclassified as a non-current liability if it meets the definition of a non-current liability in all other respects.
Borrowings	(19) Borrowings Borrowings are recognized initially at fair value, net of transaction costs incurred, and subsequently carried at amortized cost. Any difference between the proceeds, net of transaction costs, and the redemption value is recognized in the statement of comprehensive income over the period of the borrowings using the effective interest method. Fees paid on the establishment of loan facilities are recognized as transaction costs of the loan to the extent that it is probable that some or all of the facility will be drawn down. In this case, the fee is deferred until the draw-down occurs. To the extent there is no evidence that it is probable that some or all of the facility will be drawn down, the fee is capitalized as a prepayment for liquidity services and amortized over the period of the facility to which it relates.
Derecognition of financial liabilities	(20) Derecognition of financial liabilities A. The Group derecognizes a financial liability from its balance sheet when the obligation specified in the contract is discharged, cancelled or expired. B. The Group derecognizes an original financial liability and recognizes a new financial liability if the terms of an existing financial liability have substantial modifications and such modifications make significant differences (10%) to the original terms. The difference between the carrying amount of the financial liability derecognized and the consideration paid is recognized in profit or loss.
Income Tax	(21) Income Tax A. The tax expense for the period comprises current and deferred income tax. Tax is recognized in the income statement, except to the extent that it relates to items recognized in other comprehensive income or directly in equity. In this case, the tax is also recognized in other comprehensive income or directly in equity, respectively. B. The current income tax is calculated on the basis of the tax law enacted or substantively enacted at the balance sheet date in the countries where the Group operates and generates taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in which applicable tax regulation is subject to interpretation. It establishes provisions where appropriate on the basis of amounts expected to be paid to the tax authorities. C. Additional 10% undistributed earnings tax is estimated and recognized during the period when income is earned. D. Deferred income tax is recognized, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated financial statements. However, deferred income tax liabilities are not recognized if they arise from the initial recognition of goodwill; deferred income tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred income tax is determined using tax rates that have been enacted or substantively enacted by the balance sheet date and are expected to apply when the related deferred income tax asset is realized or the deferred income tax liability is settled. E. Deferred income tax liabilities are not recognized for temporary differences between the carrying amount and tax bases of investments in subsidiaries, associates and joint arrangements where the Company is able to control the timing of the reversal of the temporary differences and it is probable that the differences will not reverse in the foreseeable future. F. Deferred income tax assets and liabilties are offset when there is a legally enforceable right to offset current tax assets against current tax liabilities and when the deferred income tax assets and liabilities relate to income taxes levied by the same taxation authority on either the same taxable entity or different taxable entities where there is an intention to settle the balance on a net basis. G. Deferred income tax assets are recognized only if it is probable that future taxable profit will be available to utilize those temporary differences and losses. The investment tax credits relating to the acquisition cost of qualifying equipment or technology, qualifying research and development expenditure, qualifying personnel training expenditure and qualifying investments in significant technology companies are recognized as income tax adjustments in the period the tax credits arise.
Employee Benefits	(22) Employee Benefits A. Pensions (a) For defined contribution plans, the Group pays contributions to a publicly or privately administered pension fund. The contributions are recognized as employee benefit expenses when they are due. The Group has no legal or constructive obligations to pay further contributions if the fund does not hold sufficient assets to pay all employees the benefits. (b) For defined benefit plan, the liability recognized in the balance sheet is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The defined benefit obligation is calculated annually using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of government bonds that are denominated in the currency in which the benefits will be paid and that have terms to maturity approximating to the terms of the related pension obligation. The net interest cost is calculated by applying the discount rate to the net balance of the defined benefit obligation and the fair value of plan assets. This cost is included in employee benefit expense in the statement of profit or loss. Remeasurement gains and losses arising from experience adjustments and changes in actuarial assumptions are recognized in the period in which they occur, directly in other comprehensive income. They are included in other equity in the statement of changes in equity and in the balance sheet. Past-service costs are recognized immediately in profit or loss. Changes in the present value of the defined benefit obligation resulting from plan amendments or curtailments are recognized immediately in profit or loss as past service costs. B. Employees’ and directors’ remuneration The Group recognizes related expenses and liabilities when the Group has legal or constructive obligation and could reasonably estimate such amount. Any difference between estimated amount and distributed amount resolved in the Board of Directors in the subsequent year shall be adjusted in the profit or loss of the following year.
Provision	(23) Provision A. Provisions are recognized when the Group has a present legal or constructive obligation as a result of past events, it is probable that an outflow of resources will be required to settle the obligation, and the amount has been reliably estimated. Provisions are not recognized for future operating losses. Damages and claims on customers’ consigned materials that arise from the course of packaging and/or testing services are recognized as a provision. Related expenditure that is reimbursed under an arrangement with a third party (e.g., a supplier warranty agreement) is presented net under “Other income and expenses”. B. Provisions are measured at the present value of the expenditures expected to be required to settle the obligation using a pre-tax rate that reflects current market assessments of the time value of money and the risks specific to the obligation. The increase in the provision due to passage of time is recognized as interest expense. C. A contingent liability is a possible obligation that arises from past events and whose existence will be confrimed only by the occurrence or non-occurrence of one or more uncertain future events not wholly within the control of the entity. A present obligation that arises from past events but is not recognized because either that it is not probable that an outflow of resources embodying economic benefits will be required to settle the obligation or that the amount of the obligation cannot be measured with sufficient reliability.
Revenue Recognition	(24) Revenue Recognition The Group provides assembly, testing, and turnkey services for integrated circuits. The Group recognizes revenue when: A. the amount of revenue can be measured reliably; B. it is probable that the economic benefits associated with the transaction will flow to the entity; C. the stage of completion of the transaction at the end of the reporting period can be measured reliably; D. the costs incurred for the transaction and the cost to complete the transaction can be measured reliably. Services provided by the Group include wafer bumping, wafer sort, IC packaging and final testing. Actual services and fees of the Group may vary by customers and are pre-agreed before provision of services. The Group regards each of the captioned services as a separate stage. Fees for each stage of services are negotiated independently and the fee for a specific stage is the then market price for that stage. Revenue is recognized when each stage of services has been completed. Each stage is performed as a whole and may not be separated or proportioned. The sales discount allowance is estimated by historical experiences and recorded as a deduction to the revenue.
Lease	(25) Lease Leases in which a significant portion of the risks and rewards of ownership are retained by the lessor are classified as operating leases. Payments made under operating leases (net of incentives received from the lessor) are charged to the statement of comprehensive income on a straight-line basis over the period of the lease.

The Adoption of New and Amend46

The Adoption of New and Amended Standards and Interpretations (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Adoption of New and Amended Standards and Interpretations	Affected Items of Consolidated Balance Sheet As of Effect of As of Remark Financial assets at fair value through profit or loss, non-current $ — $ 4,135,207 $ 4,135,207 (A) Available-for-sale financial assets, non-current 4,135,207 (4,135,207 ) — (A) Contract assets - current — 1,766,801 1,766,801 (C)(a)(b) Accounts receivable, net 16,861,111 (909,849 ) 15,951,262 (B), (C)(a) Other receivables 492,081 (1,204 ) 490,877 (B) Inventories 6,123,682 (717,551 ) 5,406,131 (C)(b) Deferred income tax assets 614,733 1,805 616,538 (E) Total affected assets $ 28,226,814 $ 140,002 $ 28,366,816 Contract liabilities - current $ — $ 12,128 $ 12,128 (C)(c) Other current liabilities - other 485,482 (12,128 ) 473,354 (C)(c), (D) Deferred income tax liabilities 479,583 27,196 506,779 (E) Total affected liabilities 965,065 27,196 992,261 Unappropriated earnings 10,062,036 2,457,578 12,519,614 (A),(B),(C)(b),(E) Accumulated other comprehensive income 1,712,456 (2,344,772 ) (632,316 ) (A) Total affected equity 11,774,492 112,806 11,887,298 Total affected liabilities and equity $ 12,739,557 $ 140,002 $ 12,879,559 Explanation: (A) When adopting IFRS 9, the Group expects to reclassify available-for-sale financial assets of $4,135,207 to financial assets at fair value through profit or loss, and increase retained earnings and decrease accumulated other comprehensive income in the amounts of $2,344,772 and $2,344,772, respectively. (B) In line with the regulations of IFRS 9 on provision for impairment, accounts receivable and other receivables will be reduced by $8,370 and $1,204, respectively, and retained earnings will be decreased by $9,574. (C) Presentation of contract assets and contract liabilities When adopting IFRS 15, the Group expects to change the presentation of certain accounts in the balance sheet as follows: (a) Under IFRS 15, the services which have been rendered but not yet billed will be recognized as contract assets, but were previously presented as part of accounts receivable in the balance sheet. As of January 1, 2018, the balance of contract asset is $901,479. (b) Under IFRS 15, the services which have been processed before completion will be recognized as contract assets over time. As of January 1, 2018, the contract assets and retained earnings will be increased by $865,322 and $147,771, respectively, and the related work-in-process inventories to satisfy the performance obligation over time will be decreased by $717,551. (c) Under IFRS 15, the Group’s obligation to transfer services to a customer for which the Group has received consideration from customer are recognized as contract liabilities, but were previously presented as advance sales receipts in the balance sheet. As of January 1, 2018, the balance of contract liabilities will be $12,128. (D) Under IFRS 15, current provisions (shown as other liabilities - current are reclassified as refund liabilities (shown as other liabilities - current), but were previously presented as current provisions (shown as other liabilities - current) in the balance sheet. As of January 1, 2018, the balance is $316,391. (E) Recognition of deferred income tax assets and liabilities. When initially adopting IFRS 9 and IFRS 15, the Group will recognize deferred income tax assets and liabilities for the temporary differences resulted from the adjustments. Accordingly, deferred income tax assets and deferred income tax liabilities will be increased by $1,805 and $27,196 and retained earnings will be decreased by $25,391, respectively, on January 1, 2018.

Summary of Significant Accoun47

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Consolidated Subsidiaries	Consolidated subsidiaries: % of ownership held by the named Name of investor Name of subsidiaries Main operating activities 2016 2017 The Company SPIL (B.V.I.) Holding Limited Investment activities 100 % 100 % The Company Siliconware Investment Co., Ltd. Investment activities 100 % 100 % SPIL (B.V.I.) Holding Limited Siliconware USA, Inc. (SUI) Communications and relationship maintenance with companies headquartered in North America 100 % 100 % SPIL (B.V.I.) Holding Limited SPIL (Cayman) Holding Limited Investment activities 100 % 100 % SPIL (Cayman) Holding Limited Siliconware Technology (Suzhou) Limited Assembly and testing services 100 % 100 % SPIL (Cayman) Holding Limited Siliconware Electronics (Fujian) Co., Limited (1) Assembly and testing services — 100 % (1) Siliconware Electronics (Fujian) Co., Limited was established in July 2017 and mainly engaged in assembly and testing service for memory and logic devices with initial capital of US$45,000 thousands.
Summary of Estimated Usefull Lives of Property Plant and Equipment	C. If material part of replacing items of property, plant and equipment has different useful life from the main asset, it should be recognized and depreciated separately. Land is not depreciated. Depreciation on other assets is calculated using the straight-line method to allocate their cost to their residual values over their estimated useful lives. The estimated useful lives of property, plant and equipment are as follows: Property, plant and equipment Estimated useful lives Buildings - Main buildings 20-55 years - Construction and improvements 3-15 years Machinery and equipment 5-6 years Other equipment 2-6 years

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	As of December 31, 2016 2017 NT$ NT$ Cash on hand and petty cash 1,072 1,340 Savings accounts and checking accounts 3,876,568 5,754,845 Time deposits 20,598,630 18,687,898 24,476,270 24,444,083

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Accounts Receivable Net	As of December 31, 2016 2017 NT$ NT$ Accounts receivable 17,359,584 16,873,044 Less: Allowance for sales discounts (3,006 ) — Allowance for doubtful accounts (1,695 ) (11,933 ) 17,354,883 16,861,111
Summary of Movements of Allowance for Doubtful Accounts	Movements on the Group’s allowance for doubtful accounts are as follows: For the years ended December 31, 2016 2017 NT$ NT$ Balance as of January 1 1,695 1,695 Allowance for doubtful accounts — 11,911 Write-offs — (1,673 ) Balance as of December 31 1,695 11,933

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Inventory	As of December 31, 2016 2017 NT$ NT$ Raw materials and supplies 5,885,054 5,406,131 Work in process 613,778 717,551 6,498,832 6,123,682
Summary of Inventory Amounts Recognized in Profit or Loss	Amounts recognized in profit or loss are as follows: For the years ended December 31, 2015 2016 2017 NT$ NT$ NT$ Expense / loss incurred related to inventories : Cost of goods sold 61,196,890 65,744,357 66,696,160 Decline in market value and loss on obsolescence 20,320 54,853 69,848 Others 13,412 (37,019 ) (25,718 ) 61,230,622 65,762,191 66,740,290

Non-current Assets Held for S51

Non-current Assets Held for Sales (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Non-current Assets Held for Sales	As of December 31, 2016 2017 NT$ NT$ Plant held for sale 387,503 —

Available-for-sale Financial 52

Available-for-sale Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Available-for-sale Financial Assets	As of December 31, 2016 2017 Current Item: NT$ NT$ Fund 178,176 — Non-current Items: Common Stock 3,087,019 4,135,207 Depositary Shares 528,639 — 3,615,658 4,135,207

Investments Accounted for Usi53

Investments Accounted for Using Equity Method (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Significant Investments in Associates	Carrying Amount Percentage of ownership interest Associates Nation of Registration December 31, 2016 December 31, 2017 December 31, 2016 December 31, NT$ NT$ Individually immaterial: Yann Yuan Investment Co., Ltd. Taiwan, R.O.C. 2,383,512 2,897,644 33.33% 32.21% ASM Advanced Packaging Materials Pte. Ltd. (AAPM) Singapore 18,019 — 39.00% — 2,401,531 2,897,644
Summary of the Analysis of Other Comprehensive Income by Item	D. Set out below are the aggregate carrying value and aggregate amount of the Company’s share of operating results of individually immaterial associates. For the years ended December 31, 2015 2016 2017 NT$ NT$ NT$ Net (loss) income (183,708 ) 3,221 74,035 Other comprehensive income (loss) 1,304 (112,797 ) 380,631 Total comprehensive income (loss) (182,404 ) (109,576 ) 454,666

Financial Instruments by Cate54

Financial Instruments by Category (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Financial Instruments by Category	As of December 31, 2016 2017 NT$ NT$ Financial Assets Loans and receivables Cash and cash equivalents 24,476,270 24,444,083 Notes receivable 23,591 15,879 Accounts receivable 17,354,883 16,861,111 Other receivables 581,630 492,081 Time deposit pledged as collateral (shown as other current assets-other) 357,400 392,100 Refundable deposit (shown as other non-current assets-other) 501,924 666,936 Available-for-sale financial assets, current 178,176 — Available-for-sale financial assets, non-current 3,615,658 4,135,207 47,089,532 47,007,397 Financial Liabilities Financial liabilities at amortised cost Short-term loans 2,741,250 3,422,400 Accounts payable 8,194,647 7,456,974 Other payables 11,896,517 10,082,704 Receipts under custody (shown as other current liabilities-other) 76,231 74,149 Deposit received (shown as other current liabilities-other and other non-current liabilities) 38,907 60,499 Convertible bonds (including the current portion) 12,712,651 12,015,229 Long-term loans (including the current portion) 18,340,747 15,840,000 Long-term payable (shown as other non-current liabilities) 63,215 5,052 Financial liability at fair value through profit or loss 773,908 809,640 54,838,073 49,766,647

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Property, Plant and Equipment	A. Carrying amount by category: As of December 31, 2016 2017 NT$ NT$ Land 2,903,192 2,903,192 Buildings 19,939,679 21,859,531 Machinery and equipment 32,145,342 30,536,886 Other equipment 4,674,862 4,691,122 Construction in progress and equipment awaiting for inspection 5,717,334 2,407,334 65,380,409 62,398,065 B. Movement from period beginning to period end (a) From January 1, 2015 to December 31, 2015 i. Cost Balance at Additions Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ Land 2,903,192 — — — — 2,903,192 Buildings 22,789,352 1,423,338 — 6,798,051 (57,827 ) 30,952,914 Machinery and equipment 71,922,606 7,675,210 (7,055,018 ) 2,074,177 (232,752 ) 74,384,223 Other equipment 7,629,873 1,192,144 (629,015 ) 737,087 (29,765 ) 8,900,324 Construction in progress and equipment awaiting for inspection 10,018,645 3,719,296 — (9,609,315 ) (19,084 ) 4,109,542 115,263,668 14,009,988 (7,684,033 ) — (339,428 ) 121,250,195 ii. Accumulated depreciation and impairment Balance at Depreciation Impairment Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ NT$ Buildings 9,636,672 1,665,873 — — — (13,561 ) 11,288,984 Machinery and equipment 38,233,303 10,086,128 46,198 (6,977,590 ) 966 (135,539 ) 41,253,466 Other equipment 3,873,022 1,151,771 18,798 (623,394 ) (966 ) (17,094 ) 4,402,137 51,742,997 12,903,772 64,996 (7,600,984 ) — (166,194 ) 56,944,587 (b) From January 1, 2016 to December 31, 2016 i. Cost Balance at Additions Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ Land 2,903,192 — — — — 2,903,192 Buildings 30,952,914 1,445,512 (83,778 ) 428,540 (220,178 ) 32,523,010 Machinery and equipment 74,384,223 7,815,011 (7,204,489 ) 1,542,650 (962,141 ) 75,575,254 Other equipment 8,900,324 1,283,475 (713,787 ) 342,751 (120,433 ) 9,692,330 Construction in progress and equipment awaiting for inspection 4,109,542 4,703,546 (420 ) (2,984,597 ) (110,737 ) 5,717,334 121,250,195 15,247,544 (8,002,474 ) (670,656 ) (1,413,489 ) 126,411,120 ii. Accumulated depreciation and impairment Balance at Depreciation Impairment Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ NT$ Buildings 11,288,984 1,715,407 — (83,778 ) (278,570 ) (58,712 ) 12,583,331 Machinery and equipment 41,253,466 9,849,149 72,655 (7,155,398 ) 3,407 (593,367 ) 43,429,912 Other equipment 4,402,137 1,341,274 18,592 (663,349 ) (9,450 ) (71,736 ) 5,017,468 56,944,587 12,905,830 91,247 (7,902,525 ) (284,613 ) (723,815 ) 61,030,711 (c) From January 1, 2017 to December 31, 2017 i. Cost Balance at Additions Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ Land 2,903,192 — — — — 2,903,192 Buildings 32,523,010 1,376,617 — 2,422,828 (51,686 ) 36,270,769 Machinery and equipment 75,575,254 6,938,086 (3,217,594 ) 2,562,020 (198,414 ) 81,659,352 Other equipment 9,692,330 1,236,677 (464,434 ) 475,464 (28,143 ) 10,911,894 Construction in progress and equipment awaiting for inspection 5,717,334 2,186,703 — (5,460,312 ) (36,391 ) 2,407,334 126,411,120 11,738,083 (3,682,028 ) — (314,634 ) 134,152,541 ii. Accumulated depreciation and impairment Balance at Depreciation Impairment Disposals Transfers Exchange Balance at NT$ NT$ NT$ NT$ NT$ NT$ NT$ Buildings 12,583,331 1,841,411 — — — (13,504 ) 14,411,238 Machinery and equipment 43,429,912 10,936,614 78,468 (3,179,598 ) (8,178 ) (134,752 ) 51,122,466 Other equipment 5,017,468 1,637,955 9,763 (434,993 ) 8,178 (17,599 ) 6,220,772 61,030,711 14,415,980 88,231 (3,614,591 ) — (165,855 ) 71,754,476

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Intangible Assets	As of December 31, 2016 2017 NT$ NT$ License Fee 31,460 18,443 Software 144,402 100,825 175,862 119,268 B. Movement from period beginning to period end (a) From January 1, 2015 to December 31, 2015 i. Cost Item Balance at January 1 Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 608,138 — (495,890 ) — 112,248 Software 174,858 112,692 (84,826 ) (410) 202,314 782,996 112,692 (580,716 ) (410) 314,562 ii. Accumulated amortization Item Balance at January 1 Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 433,876 120,693 (495,890 ) — 58,679 Software 99,950 48,111 (84,826 ) (126) 63,109 533,826 168,804 (580,716 ) (126) 121,788 (b) From January 1, 2016 to December 31, 2016 i. Cost Item Balance at Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 112,248 — (4,354 ) — 107,894 Software 202,314 71,011 (32,320 ) (1,818 ) 239,187 314,562 71,011 (36,674 ) (1,818 ) 347,081 ii. Accumulated amortization Item Balance at Additions Disposals Exchange Balance at NT$ NT$ NT$ NT$ NT$ License Fee 58,679 22,109 (4,354 ) — 76,434 Software 63,109 64,616 (32,320 ) (620 ) 94,785 121,788 86,725 (36,674 ) (620 ) 171,219 (c) From January 1, 2017 to December 31, 2017 i. Cost Item Balance at January 1 Additions Disposals Exchange net Balance at NT$ NT$ NT$ NT$ NT$ License Fee 107,894 — (75,094 ) — 32,800 Software 239,187 29,237 (23,689 ) (427) 244,308 347,081 29,237 (98,783 ) (427) 277,108 ii. Accumulated amortization Item Balance at January 1 Additions Disposals Exchange net Balance at NT$ NT$ NT$ NT$ NT$ License Fee 76,434 13,017 (75,094 ) — 14,357 Software 94,785 72,531 (23,689 ) (144) 143,483 171,219 85,548 (98,783 ) (144) 157,840

Financial Liabilities at Fair57

Financial Liabilities at Fair Value Through Profit or Loss (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Financial Liabilities at Fair Value through Profit or Loss	As of December 31, 2016 and 2017, the detail of financial liabilities at fair value through profit or loss is as follow: As of December 31, 2016 2017 NT$ NT$ Conversion option, redemption option and put option of convertible bonds upon initial recognition(Note 17) 774,319 774,319 Valuation adjustments (411 ) 35,321 773,908 809,640

Other Payables (Tables)

Other Payables (Tables)	12 Months Ended
	Dec. 31, 2017
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Schedule of Other Paybles	As of December 31, 2016 2017 NT$ NT$ Payables for equipment 3,486,635 2,234,142 Payables for employees’ compensations 3,880,980 3,476,527 Others 4,528,902 4,372,035 11,896,517 10,082,704

Convertible Bonds (Tables)

Convertible Bonds (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of convertible bonds	As of December 31, 2016 and 2017, the detail of convertible bonds is as follow: As of December 31, 2016 2017 NT$ NT$ Unsecured overseas convertible bonds 13,580,212 12,533,316 Less: Discounts on bonds payable (867,561 ) (518,087 ) Current portion (12,712,651 ) — — 12,015,229

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Short-term Loans	As of December 31, 2016 2017 NT$ NT$ Credit loans 2,741,250 3,422,400 Interest rates 1.3250% ~ 1.6440% 1.6764% ~ 2.5112%
Summary of Long-term Loans	B. Long-term Loans Loan period and repayment method As of December 31, 2016 2017 NT$ NT$ Syndicated bank loans: 2012.8.10-2017.8.10 Including US$33,333 thousand in December 31, 2016. Repayables in 6 semi-annually installments starting from February, 2015 2,162,333 — Other bank loans: 2013.12.31-2016.12.31 /Extended to 2019.12.30, and increased by $1,000,000 on 2017.01.19. Repayables in 3 semi-annually installments starting from December 28, 2018 1,500,000 2,500,000 2014.8.11-2018.12.13 Repayables in 5 semi-annually installments starting from December 13, 2016 680,000 340,000 2014.8.11-2018.12.10 Repayables in 6 semi-annually installments starting from June 13, 2016 1,000,000 500,000 2014.8.11-2019.8.11 Repayables in 6 semi-annually installments starting from February 10, 2017 1,500,000 1,000,000 2015.7.1-2020.7.1 Repayables in 6 semi-annually installments starting from January 2, 2018 1,500,000 1,500,000 2015.11.13-2020.11.13 Repayables in 6 semi-annually installments starting from May 11, 2018 1,000,000 1,000,000 2016.07.19-2021.01.10 Repayables in 6 semi-annually installments starting from July 10, 2018 3,000,000 3,000,000 2016.07.19-2021.07.19 Repayables in 6 semi-annually installments starting from January 18, 2019 4,000,000 4,000,000 2016.12.30-2021.12.30 Repayables in 6 semi-annually installments starting from June 28, 2019 2,000,000 2,000,000 Less: Arrangement fee of syndicated loans (1,586 ) — Current portion (3,500,747 ) (3,173,333 ) 14,840,000 12,666,667 Interest rate 1.1287%-2.3890% 1.1358%-2.3890% (1) In order to fulfill the requirements of operational and capital expenditures, the Company entered into syndicated loan agreements with eleven financial institutions, including Mega International Commercial Bank, the management bank, in August 2012. All long-term loans are with credit periods of five years and are floating interest rate loans. (2) Pursuant to the loan agreement, the Company should maintain, on a semi-annual and annual consolidated basis, certain debt covenants, such as current ratio, liability to tangible net worth ratio as well as the ratio of interest coverage. Up to December 31, 2017, the Company has been in compliance with all the debt covenants.

Post-employment Benefit (Tables

Post-employment Benefit (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Amounts Arising from the Defined Benefit Obligation Recognized	(1) Except for the pension plans for executive officers, the amounts arising from the defined benefit obligation recognized on the balance sheets are as follows: As of December 31, 2016 2017 NT$ NT$ Present value of defined benefit obligations 2,550,824 2,513,060 Fair value of plan assets (1,177,592 ) (1,159,337 ) Net defined benefit liability 1,373,232 1,353,723
Summary of Movements in Net Defined Benefit Liabilities	(2) Movements in net defined benefit liabilities are as follows: (a) For the year ended December 31, 2015 Present value of Fair value of Net defined NT$ NT$ NT$ Balance at January 1 2,225,935 (1,192,196 ) 1,033,739 Current service cost 20,475 — 20,475 Interest expense (income) 49,670 (26,976 ) 22,694 70,145 (26,976 ) 43,169 Remeasurements: Experience adjustments 10,493 — 10,493 Changes in demographic assumptions 18,021 — 18,021 Changes in financial assumptions 145,514 — 145,514 Return of plan assets(excluding amount included in net interest expense) — 5,814 5,814 174,028 5,814 179,842 Pension fund contribution — (49,440 ) (49,440 ) Paid Pension (77,827 ) 77,827 — Balance at December 31 2,392,281 (1,184,971 ) 1,207,310 (b) For the year ended December 31, 2016 Present value of Fair value of Net defined NT$ NT$ NT$ Balance at January 1 2,392,281 (1,184,971 ) 1,207,310 Current service cost 19,165 — 19,165 Interest expense (income) 41,441 (20,754 ) 20,687 60,606 (20,754 ) 39,852 Remeasurements: Experience adjustments 19,709 — 19,709 Changes in financial assumptions 149,878 — 149,878 Return of plan assets(excluding amount included in net interest expense) — 6,297 6,297 169,587 6,297 175,884 Pension fund contribution — (49,814 ) (49,814 ) Paid Pension (71,650 ) 71,650 — Balance at December 31 2,550,824 (1,177,592 ) 1,373,232 (c) For the year ended December 31, 2017 Present value of Fair value of Net defined NT$ NT$ NT$ Balance at January 1 2,550,824 (1,177,592 ) 1,373,232 Current service cost 17,171 — 17,171 Interest expense (income) 37,817 (17,601 ) 20,216 54,988 (17,601 ) 37,387 Remeasurements: Experience adjustments (13,625 ) — (13,625 ) Return of plan assets(excluding amount included in net interest expense) — 6,281 6,281 (13,625 ) 6,281 (7,344 ) Pension fund contribution — (49,552 ) (49,552 ) Paid Pension (79,127 ) 79,127 — Balance at December 31 2,513,060 (1,159,337 ) 1,353,723
Summary of Constitution of Fair Value Of Plan Assets	(3) Under the Labor Standards Law, the rate of return on assets shall not be less than the average interest rate on a two-year time deposit published by the local banks and the government is responsible for any shortfall in the event that the rate of return is less than the required rate of return. The plan assets are held in a commingled fund which is operated and managed by the government’s designated authorities; as such, the Company does not have any right to intervene in the investments of the Funds. The constitution of fair value of plan assets as of December 31, 2016 and 2017 is as follows: As of December 31, 2016 2017 NT$ NT$ Cash 268,962 270,473 Equity instruments 580,435 574,452 Debt instruments 328,195 314,412 1,177,592 1,159,337
Summary of Principal Actuarial Assumptions	(4) Principal actuarial assumptions for the reporting period are as follows: As of December 31, 2016 2017 Discount rate 1.50 % 1.50 % Future salary increases 2.25 % 2.25 %
Summary of Defined Benefit Obligation	(5) For the years ended December 31, 2016 and 2017, if the aforementioned discount rate and future salary increase rate are 0.5% higher (lower) than management’s estimates, the impact on the carrying amounts of defined benefit obligations is as follows: Impact on defined benefit obligations As of December 31, 2016 0.5% increase in 0.5% decrease in NT$ NT$ Discount rate (150,030 ) 163,143 Future salary increase rate 161,138 (149,723 ) Impact on defined benefit obligations As of December 31, 2017 0.5% increase in 0.5% decrease in NT$ NT$ Discount rate (139,783 ) 151,499 Future salary increase rate 149,644 (139,499 )
Summary of Expected Maturity Analysis of Undiscounted Defined Benefit Obligation	(7) As of December 31, 2017, the weighted average duration of the defined benefit plan is 11.6 years. Expected maturity analysis of undiscounted defined benefit obligations was as follows: NT$ Within 1 year 65,895 1-2 year(s) 73,658 2-3 years 87,648 Over 3 years 2,876,889 3,104,090

Retained Earnings (Tables)

Retained Earnings (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Distributions	G. The appropriations of 2015 and 2016 earnings have been approved at the Shareholders’ meeting on May 16, 2016 and June 28, 2017, respectively. The appropriations and dividends per share were as follows: For the Years Ended December 31, 2015 2016 Amount Dividends Amount Dividends NT$ NT$ Provision of Legal reserve 876,226 993,316 Cash dividends 8,725,811 2.80 5,453,632 1.75

Other Equity Items (Tables)

Other Equity Items (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Other Equity Items	Unrealized Gain on Valuation of Available-for- Exchange Difference on Remeasurements of NT$ NT$ NT$ As of January 1, 2015 3,670,115 720,253 23,339 Changes in fair value of financial instruments - pretax (2,406,287 ) — — - tax 19,610 — — Recognition of changes in fair value of financial instruments in profit or loss - pretax 1,856,442 — — Differences in translation - equity method investments - pretax — (223,940 ) — - tax — (40 ) — Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method - pretax — (3,965 ) — - tax — 674 — Remeasurements of post-employment benefit obligations - pretax — — (179,842 ) - tax — — 30,572 As of December 31, 2015 3,139,880 492,982 (125,931 ) Unrealized Gain on Valuation of Available-for- Exchange Difference on Remeasurements of NT$ NT$ NT$ As of January 1, 2016 3,139,880 492,982 (125,931 ) Changes in fair value of financial instruments - pretax (1,229,348 ) — — - tax 242,555 — — Recognition of changes in fair value of financial instruments in profit or loss - pretax (239,757 ) — — - tax 19,804 — — Share of other comprehensive income of associates - pretax (121,957 ) — — - tax 10,981 — — Differences in translation - equity method investments - pretax — (908,801 ) — - tax — 570 — Remeasurements of post-employment benefit obligations - pretax — — (177,806 ) - tax — — 30,227 As of December 31, 2016 1,822,158 (415,249 ) (273,510 ) Unrealized Gain on Valuation of Available-for- Exchange Difference on Remeasurements of NT$ NT$ NT$ As of January 1, 2017 1,822,158 (415,249 ) (273,510 ) Changes in fair value of financial instruments - pretax 519,549 — — - tax (63,395 ) — — Recognition of changes in fair value of financial instruments in profit or loss - pretax (54,374 ) — — - tax 13,734 — — Share of other comprehensive income of associates - pretax 418,944 — — - tax (37,721 ) — — Differences in translation - equity method investments - pretax — (227,787 ) — - tax — 111 — Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method - pretax — 1,464 — - tax — (305 ) — Remeasurements of post-employment benefit obligations - pretax — — 10,647 - tax — — (1,810 ) As of December 31, 2017 2,618,895 (641,766 ) (264,673 )

Expenses by Nature (Tables)

Expenses by Nature (Tables)	12 Months Ended
	Dec. 31, 2017
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Summary of Employee Benefit Expenses	For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Employee benefit expenses Salaries and bonuses 15,339,459 16,155,821 15,041,087 Post employment benefits 577,074 655,565 769,153 Directors’ remuneration 112,801 127,111 91,750 Others 2,026,237 2,190,194 2,607,597 18,055,571 19,128,691 18,509,587 Depreciation and amortization expenses 13,513,985 13,291,190 14,625,299

Other Income and Expenses (Tabl

Other Income and Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Income and Expenses	For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Loss on damages and claims (374,613 ) (298,778 ) (120,744 ) Gains on disposal of property, plant and equipment and other assets 31,293 32,615 150,579 Gains on disposal of non-current assets held for sales — — 19,402 Impairment loss on property, plant and equipment (64,996 ) (91,247 ) (88,231 ) Others 152,499 240,404 166,040 (255,817 ) (117,006 ) 127,046

Other Gains and Losses, Net (Ta

Other Gains and Losses, Net (Tables)	12 Months Ended
	Dec. 31, 2017
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Schedule of Other Gains And Losses Net	For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Foreign exchange gain (loss)—net (77,439 ) (104,365 ) 39,976 Gains on reversal of impairment loss of non-financial assets (Note 11(C)) 134,992 — — 57,553 (104,365 ) 39,976

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2017
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Income Taxes Recognized in Profit or Loss	A. Income taxes recognized in profit or loss for the years ended December 31, 2015, 2016 and 2017 are as follows: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Current income tax expense Recognition for the current period 1,741,385 1,356,232 1,188,463 Provision of additional 10% tax on undistributed earnings 906,273 904,395 982,843 Reversal of additional 10% tax on undistributed earnings due to dividend distribution (1,056,043 ) (788,603 ) (904,395 ) Income tax adjustments for prior years (39,435 ) (6,336 ) (6,759 ) 1,552,180 1,465,688 1,260,152 Deferred income tax expense Temporary differences (186,121 ) 401,511 265,427 Income tax expense recognized in profit or loss 1,366,059 1,867,199 1,525,579
Profit Before Tax Differs from the Theoretical Amount that Would Arise using the Weighted Average Tax Rate	B. The tax on the Group’s profit before tax differs from the theoretical amount that would arise using the weighted average tax rate applicable to profits of the consolidated entities as follows: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Income tax expense calculated at the statutory tax rates applicable to respective countries 2,057,890 2,300,048 1,783,328 Expense disallowed (deductible income) by tax regulation 319,835 113,971 (13,203 ) Tax exempt income by tax regulation (736,103 ) (572,372 ) (389,163 ) Temporary difference not recognized as deferred income tax liabilities (179,130 ) (156,588 ) (135,960 ) Change in assessment of realization of deferred income tax assets (1,071 ) — — Effect from Alternative Minimum Tax 88,944 72,684 32,688 Provision of additional 10% tax on undistributed earnings 906,273 904,395 982,843 Adjustment: over provision from prior years (1,090,579 ) (794,939 ) (911,703 ) Deferred tax effect of earnings of subsidiaries — — 176,749 Income tax expense recognized in profit or loss 1,366,059 1,867,199 1,525,579
Income Taxes Recognized in Other Comprehensive Income	C. Income taxes recognized in other comprehensive income for the years ended December 31, 2015, 2016 and 2017 are as follows: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Unrealized gain/loss on available-for-sale financial assets 19,610 262,359 (49,661 ) Share of other comprehensive income of associates — 10,981 (37,721 ) Exchange difference on translation of foreign financial statements 634 570 (194 ) Remeasurements of post-employment benefit obligation 30,572 30,227 (1,810 ) 50,816 304,137 (89,386 )
Changes in deferred income tax assets and liabilities	D. Changes in deferred income tax assets and liabilities for the years ended December 31, 2015, 2016 and 2017 are as follows: For the Year Ended December 31, 2015 January 1 Profit or Other Effect of December 31 NT$ NT$ NT$ NT$ NT$ Deferred income tax assets Temporary differences Unrealized sales allowance 47,722 (43,330 ) — (40 ) 4,352 Convertible bonds 95,623 125,131 — — 220,754 Post-employment benefit obligations 165,371 (2,254 ) 30,572 — 193,689 Unrealized losses on financial liabilities at fair value through profit or loss 54,610 119,572 — — 174,182 Others 332,786 (13,352 ) 634 (991 ) 319,077 696,112 185,767 31,206 (1,031 ) 912,054 Deferred income tax liabilities Temporary differences Unrealized gains on available-for-sale financial assets (282,648 ) — 19,610 — (263,038 ) Unrealized gains on property, plant and equipment (13,567 ) (14,828 ) — 697 (27,698 ) Others (60,003 ) 15,182 — 972 (43,849 ) (356,218 ) 354 19,610 1,669 (334,585 ) Net deferred income tax assets 339,894 186,121 50,816 638 577,469 For the Year Ended December 31, 2016 January 1 Profit or Other Effect of December 31 NT$ NT$ NT$ NT$ NT$ Deferred income tax assets Temporary differences Unrealized sales allowance 4,352 (1,807 ) — (151 ) 2,394 Convertible bonds 220,754 11,828 — — 232,582 Post-employment benefit obligations 193,689 19,610 30,227 — 243,526 Unrealized losses on financial liabilities at fair value through profit or loss 174,182 (174,182 ) — — — Others 319,077 (43,697 ) 570 (1,740 ) 274,210 912,054 (188,248 ) 30,797 (1,891 ) 752,712 Deferred income tax liabilities Temporary differences Unrealized gains on available-for-sale financial assets (263,038 ) (139,835 ) 262,359 — (140,514 ) Unrealized gains on property, plant and equipment (27,698 ) (39,646 ) — 4,828 (62,516 ) Others (43,849 ) (33,782 ) 10,981 5,320 (61,330 ) (334,585 ) (213,263 ) 273,340 10,148 (264,360 ) Net deferred income tax assets 577,469 (401,511 ) 304,137 8,257 488,352 For the Year Ended December 31, 2017 January 1 Profit or Other Effect of December 31 NT$ NT$ NT$ NT$ NT$ Deferred income tax assets Temporary differences Convertible bonds 232,582 (120,794 ) — — 111,788 Post-employment benefit obligations 243,526 (12,559 ) (1,810 ) — 229,157 Unrealized losses on inventories 50,380 19,594 — (231 ) 69,743 Provisions 70,678 (29,175 ) — — 41,503 Compensated absences payable 69,876 3,469 — (36 ) 73,309 Others 85,670 30,536 (26,935 ) (38 ) 89,233 752,712 (108,929 ) (28,745 ) (305 ) 614,733 Deferred income tax liabilities Temporary differences Gains from investment for using equity method — (176,749 ) — — (176,749 ) Unrealized gains on available-for-sale financial assets (140,514 ) (21,291 ) (49,660 ) — (211,465 ) Unrealized gains on property, plant and equipment (62,516 ) 1,864 — 1,219 (59,433 ) Others (61,330 ) 39,678 (10,981 ) 697 (31,936 ) (264,360 ) (156,498 ) (60,641 ) 1,916 (479,583 ) Net deferred income tax assets 488,352 (265,427 ) (89,386 ) 1,611 135,150
Unrecognized Deferred Income Tax Liabilities Relating to Taxable Temporary Differences for Investments in Foreign Subsidiaries	E. Unrecognized deferred income tax liabilities relating to the taxable temporary differences for investments in foreign subsidiaries are: As of December 31, 2016 2017 NT$ NT$ Investment in foreign subsidiaries 6,693,787 7,266,412

Earnings Per Share (EPS) (Table

Earnings Per Share (EPS) (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Schedule of Earnings Per Share	For the year ended December 31, 2015 Income after tax Weighted average Earnings per share NT$ (in thousands) NT$ Basic earnings per share Net income 9,011,463 3,116,361 2.89 Dilutive effect of employee compensation — 33,769 Diluted earnings per share 9,011,463 3,150,130 2.86 For the year ended December 31, 2016 Income after tax Weighted average Earnings per share NT$ (in thousands) NT$ Basic earnings per share Net income 9,806,937 3,116,361 3.15 Dilutive effect of employee compensation — 28,643 Dilutive effect of convertible bonds (779,928 ) 265,677 Diluted earnings per share 9,027,009 3,410,681 2.65 For the year ended December 31, 2017 Income after tax Weighted average Earnings per share NT$ (in thousands) NT$ Basic earnings per share Net income 7,171,534 3,116,361 2.30 Dilutive effect of employee compensation — 22,122 Dilutive effect of convertible bonds (549,203 ) 275,388 Diluted earnings per share 6,622,331 3,413,871 1.94

Supplemental Cash Flow Inform69

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Investment Activities	A. Investment activities with partial cash payments For the years ended December 31, 2015 2016 2017 NT$ NT$ NT$ Purchase of property, plant and equipment 14,009,988 15,247,544 11,738,083 (Decrease)/ increase in prepayment for equipment (4,798 ) 21,754 (32,435 ) Decrease/ (increase) in equipment payable, net (838,740 ) 89,820 1,252,493 (Increase)/ decrease in notes payable of construction 699,900 — — Effect of foreign currency exchange (10,919 ) (63,997 ) (25,486 ) Cash payment for acquisition of property, plant, and equipment 13,855,431 15,295,121 12,932,655
Summary of Reconcilation of Liablities from Financing Activities	B. Reconciliation of liabilities arising from financing activities: Non-Cash Charges As of January 1, 2017 Cash flows Foreign Fair Value Amortization Amortization As of December 31, 2017 NT$ NT$ NT$ NT$ NT$ NT$ NT$ Long-term loans (include the current portion) 18,340,747 (2,413,112 ) (89,221 ) — — 1,586 15,840,000 Short-term loans 2,741,250 912,080 (230,930 ) — — — 3,422,400 Convertible bonds (include the current portion) 12,712,651 — (987,093 ) — 289,671 — 12,015,229 Refundable deposits 38,907 21,749 (157 ) — — — 60,499 Total liabilities from financing activities 33,833,555 (1,479,283 ) (1,307,401 ) — 289,671 1,586 31,338,128 Financial liability at fair value through profit or loss 773,908 — — 35,732 — — 809,640
Summary of Non-Cash Investment Activities	C. Non-cash investing activities: (1) As mentioned in Note 10(C), as a result of the merger between ChipMOS Technologies Inc., and ChipMOS Technologies (Bermuda) Ltd., shareholders of ChipMOS Technologies (Bermuda) Ltd. received US$3.71 dollars in cash and 0.9355 share of American Depository Shares (“ADS”) in exchange for each share in ChipMOS Technologies (Bermuda) Ltd. Each ADS represents 20 new common shares issued by ChipMOS Technologies Inc. For the year ended NT$ Available-for-sale financial assets, non-current - ADS of ChipMOS Technologies Inc. 655,066 Available-for-sale financial assets, non-current - ChipMOS Technologies (Bermuda) Ltd. : Decrease in available-for-sale financial assets, non-current (748,540 ) Other income (51,923 ) Increase in other receivables 145,397 —
Summary of Capital Return	(2) As mentioned in Note 11(C), Interconnect made a capital reduction in December 2015. The 39% interests in AAPM were distributed to the Company as capital return. For the year ended NT$ Acquisition of investments accounted for using the equity method-AAPM 137,011 Disposal of Associate-Interconnect: Decrease in difference on translation (Show as other equity item) 3,291 Decrease in deferred tax liabilities 674 Decrease in investments accounted for using the equity method (1,409 ) Gains on disposal of investments (139,567 ) —

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Schedule of Transactions Between Company and Other Related Parties	The transactions between the Group and other related parties are as follows: A. Disposal of Financial Assets For the year ended December 31, 2016 Financial Statement Account Shares Marketable Securities Type and Name Disposal of Gain on NT$ NT$ Associates Available-for-sale financial 57,810 Hsieh Yong Capital Co., Ltd. (Stock) 376,943 206,943
Schedule of Personnel Compensations to Directors, Supervisors, and Managements	E. Personnel compensations to Directors and Managements For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Short-term employee benefits 370,943 443,802 313,922 Post-employment benefits 2,866 65,217 2,991 373,809 509,019 316,913

Assets Pledged as Collateral (T

Assets Pledged as Collateral (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Assets Pledged as Collateral	The following assets have been pledged as collateral against certain obligations of the Company: As of December 31, Assets 2016 2017 Subject of collateral NT$ NT$ Time deposits (shown as other current assets - other) 357,400 392,100 Guarantees for customs duties and land leased from Science Park Administration

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Future Minimum Lease Payments Under Non-cancellable Operating Leases	C. Future minimum lease payments under the non-cancellable operating leases are as follows: As of December 31, 2017 NT$ Within 1 year 143,573 1-5 year(s) 298,888 Over 5 years 657,830 1,100,291

Financial Risk Management (Tabl

Financial Risk Management (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Exposure to Foreign Exchange Risks	The Group’s exposure to foreign exchange risk is as follows: As of December 31, 2016 (Foreign currencies: functional currencies) Sensitivity analysis Foreign Exchange Movement Impact to (NT$) Financial assets Monetary assets USD:NTD 800,272 32.200 1 % 257,688 USD:RMB 17,786 6.9370 1 % 5,727 Nonmonetary assets USD:NTD 21,951 32.200 N/A N/A Investments accounted for using the equity method USD:NTD 559 32.250 N/A N/A Financial Liabilities Monetary liabilities USD:NTD 596,659 32.300 1 % 192,721 USD:RMB 113,280 6.9370 1 % 36,589 JPY:NTD 3,838,753 0.2776 1 % 10,656 JPY:RMB 596,668 0.0596 1 % 1,656 As of December 31, 2017 (Foreign currencies: functional currencies) Sensitivity analysis Foreign Exchange Movement Impact to (NT$) Financial assets Monetary assets USD:NTD 588,521 29.710 1 % 174,850 USD:RMB 43,141 6.5342 1 % 12,817 Financial Liabilities Monetary liabilities USD:NTD 550,842 29.810 1 % 164,206 USD:RMB 158,166 6.5342 1 % 47,149 JPY:NTD 2,912,882 0.2662 1 % 7,754 JPY:RMB 1,013,068 0.0579 1 % 2,697 Note: Currency risk does not arise from financial instruments that are nonmonetary items and thus are not subject to sensitivity analysis.
Summary of Aging Analysis of Accounts Receivable	(3) Aging analysis of accounts receivables that were past due is as follows: As of December 31, 2016 Total Impaired Unimpaired NT$ NT$ NT$ 1-90 days 933,715 — 933,715 91-180 days 54,947 — 54,947 Over 180 days 5,401 1,695 3,706 994,063 1,695 992,368 As of December 31, 2017 Total Impaired Unimpaired NT$ NT$ NT$ 1-90 days 1,322,342 — 1,322,342 91-180 days 15,165 10,238 4,927 Over 180 days 3,561 1,695 1,866 1,341,068 11,933 1,329,135 Note: As of December 31, 2016 and 2017, no impairment loss incurred on accounts receivables that are not past due.
Summary of Maturity of Financial Liabilities	The table below summarizes the maturity profile of the Group’s financial liabilities based on contractual terms (including principals and interests payments), which is presented on an undiscounted basis: As of December 31, 2016 Less than 1 year 1-2 years 2-3 years Over 3 years Total NT$ NT$ NT$ NT$ NT$ Short-term Loans 2,761,041 — — — 2,761,041 Accounts Payable 8,194,647 — — — 8,194,647 Other Payables 11,896,517 — — — 11,896,517 Other Current Liabilities-Others 106,859 — — — 106,859 Convertible Bonds (include the current portion) 13,312,768 — — — 13,312,768 Long-term Loans (include the current portion) 3,714,850 2,851,419 5,959,549 6,402,421 18,928,239 Other Non-Current Liabilities — 63,215 — 8,279 71,494 39,986,682 2,914,634 5,959,549 6,410,700 55,271,565 As of December 31, 2017 Less than 1 1-2 years 2-3 years Over 3 Total NT$ NT$ NT$ NT$ NT$ Short-term Loans 3,454,355 — — — 3,454,355 Accounts Payable 7,456,974 — — — 7,456,974 Other Payables 10,082,704 — — — 10,082,704 Other Current Liabilities-Others 133,212 — — — 133,212 Convertible Bonds (include the current portion) — 12,533,316 — — 12,533,316 Long-term Loans (include the current portion) 3,363,170 6,462,779 3,889,463 2,513,314 16,228,726 Other Non-Current Liabilities — 5,052 208 1,228 6,488 24,490,415 19,001,147 3,889,671 2,514,542 49,895,775

Fair Value Information on Fin74

Fair Value Information on Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Convertible Bonds	As of December 31, 2016 and 2017, the book value and fair value of the convertible bonds (include the current portion) are as follow: Carrying Amount Fair Value (Level 3) NT$ NT$ December 31, 2016 12,712,651 12,841,188 December 31, 2017 12,015,229 12,007,468
Summary of Financial Instruments Measured at Fair Value	C. The Company’s financial instruments measured at fair value are as follows: Recurring basis As of December 31, 2016 Level 1 Level 2 Level 3 NT$ NT$ NT$ Available-for-sale financial assets 3,615,658 178,176 — Financial liability at fair value through profit or loss — — 773,908 As of December 31, 2017 Level 1 Level 2 Level 3 NT$ NT$ NT$ Available-for-sale financial assets 4,135,207 — — Financial liability at fair value through profit or loss — — 809,640
Summary of Reconciliation of Level 3 Fair Value Measurements of Financial Liabilities	(5) Reconciliation of Level 3 fair value measurements of financial liabilities 2015 2016 2017 NT$ NT$ NT$ As of January 1 1,095,552 1,798,920 773,908 Losses (Gains) recognized in profit or loss 703,368 (1,025,012 ) 35,732 As of December 31 1,798,920 773,908 809,640

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Summary of Breakdown of Revenue From Different Products and Services	A. Breakdown of the revenue from different products and services: For the Years Ended December 31, 2015 2016 2017 NT$ NT$ NT$ Packaging 72,752,428 74,315,486 70,851,943 Testing 9,551,025 10,227,996 11,983,667 Others 536,469 568,431 718,775 82,839,922 85,111,913 83,554,385
Summary of Operations in Different Geographic Areas	Operations in different geographic areas: For the Years Ended December 31, 2015 2016 2017 Revenues Noncurrent Assets Revenues Noncurrent Assets Revenues Noncurrent Assets NT$ NT$ NT$ NT$ NT$ NT$ United States 30,076,050 1,553 33,624,139 1,728 32,018,540 1,739 China 21,318,660 8,068,694 22,724,680 9,014,191 24,778,540 11,803,140 Taiwan 18,106,693 59,606,745 19,683,484 59,371,230 15,494,157 54,572,997 Europe 8,470,707 — 6,794,827 — 8,315,142 — Others 4,867,812 122,748 2,284,783 18,019 2,948,006 — 82,839,922 67,799,740 85,111,913 68,405,168 83,554,385 66,377,876

Valuation and Qualifying Acco76

Valuation and Qualifying Account (Tables)	12 Months Ended
	Dec. 31, 2017
Text block1 [abstract]
Valuation and Qualifying Account	Description Balance at Additions Deductions Exchange Balance NT$ NT$ NT$ NT$ NT$ For the year ended 2015 Allowance for doubtful accounts 1,695 — — — 1,695 Allowance for sales discounts 275,705 152,224 413,668 (205 ) 14,056 Allowance for loss on obsolescence and decline in market value of inventory 143,348 20,480 — (772 ) 163,056 Allowance for loss on idle assets 93,361 64,996 45,220 (580 ) 112,557 For the year ended 2016 Allowance for doubtful accounts 1,695 — — — 1,695 Allowance for sales discounts 14,056 — 11,050 — 3,006 Allowance for loss on obsolescence and decline in market value of inventory 163,056 112,374 — (3,978 ) 271,452 Allowance for loss on idle assets 112,557 91,247 76,822 (1,623 ) 125,359 For the year ended 2017 Allowance for doubtful accounts 1,695 11,911 1,673 — 11,933 Allowance for sales discounts 3,006 — 3,006 — — Allowance for loss on obsolescence and decline in market value of inventory 271,452 69,869 — (935 ) 340,386 Allowance for loss on idle assets 125,359 88,231 97,961 (489 ) 115,140

The Adoption of New and Amend77

The Adoption of New and Amended Standards and Interpretations - Summary of Adoption of New and Amended Standards and Interpretations (Detail) $ in Thousands, $ in Thousands	Jan. 01, 2018TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Available-for-sale financial assets, non-current		$ 139,515	$ 4,135,207	$ 3,615,658
Accounts receivable, net		568,863	16,861,111	17,354,883
Other receivables		16,602	492,081	581,630
Inventories		206,602	6,123,682	6,498,832
Deferred income tax assets		20,740	614,733	752,712
TOTAL ASSETS		4,076,448	120,825,916	123,727,307
Other current liabilities - other		16,379	485,482	615,497
Deferred income tax liabilities		16,180	479,583	264,360
Total Liabilities		1,801,885	53,407,881	58,606,849
Unappropriated earnings		339,475	10,062,036	9,337,450
Accumulated other comprehensive income		57,775	1,712,456	1,133,399
Total Shareholders' Equity		2,274,563	67,418,035	65,120,458	$ 69,529,225	$ 70,773,742
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY		$ 4,076,448	120,825,916	$ 123,727,307
Previously stated [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Available-for-sale financial assets, non-current			4,135,207
Accounts receivable, net			16,861,111
Other receivables			492,081
Inventories			6,123,682
Deferred income tax assets			614,733
TOTAL ASSETS			28,226,814
Other current liabilities - other			485,482
Deferred income tax liabilities			479,583
Total Liabilities			965,065
Unappropriated earnings			10,062,036
Accumulated other comprehensive income			1,712,456
Total Shareholders' Equity			11,774,492
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY			12,739,557
Effect of adoption of new standards [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss, non-current			4,135,207
Available-for-sale financial assets, non-current			(4,135,207)
Contract assets - current			1,766,801
Accounts receivable, net			(909,849)
Other receivables			(1,204)
Inventories			(717,551)
Deferred income tax assets			1,805
TOTAL ASSETS			140,002
Contract liabilities - current			12,128
Other current liabilities - other			(12,128)
Deferred income tax liabilities			27,196
Total Liabilities			27,196
Unappropriated earnings			2,457,578
Accumulated other comprehensive income			(2,344,772)
Total Shareholders' Equity			112,806
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY			$ 140,002
Increase (decrease) due to changes in accounting policy [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss, non-current	$ 4,135,207
Contract assets - current	1,766,801
Accounts receivable, net	15,951,262
Other receivables	490,877
Inventories	5,406,131
Deferred income tax assets	616,538
TOTAL ASSETS	28,366,816
Contract liabilities - current	12,128
Other current liabilities - other	473,354
Deferred income tax liabilities	506,779
Total Liabilities	992,261
Unappropriated earnings	12,519,614
Accumulated other comprehensive income	(632,316)
Total Shareholders' Equity	11,887,298
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 12,879,559

The Adoption of New and Amend78

The Adoption of New and Amended Standards and Interpretations - Summary of Adoption of New and Amended Standards and Interpretations (Parenthetical) (Detail) $ in Thousands, $ in Thousands	Jan. 01, 2018TWD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Available-for-sale financial assets, non-current			$ 139,515	$ 4,135,207	$ 3,615,658
Increase (decrease) accumulated other comprehensive income			339,475	10,062,036	9,337,450
Accounts receivable			568,863	16,861,111	17,354,883
Other receivables			16,602	492,081	581,630
Other current liabilities - other			16,379	485,482	615,497
Deferred income tax assets			20,740	614,733	752,712
Deferred income tax liabilities			$ 16,180	479,583	$ 264,360
Effect of adoption of new standards [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss, non-current				4,135,207
Available-for-sale financial assets, non-current				(4,135,207)
Increase (decrease) accumulated other comprehensive income				2,457,578
Accounts receivable				(909,849)
Other receivables				(1,204)
Increase (decrease) in retained earnings		$ 25,391
Contract asset				1,766,801
Contract liabilities - current				12,128
Other current liabilities - other				(12,128)
Deferred income tax assets				1,805
Deferred income tax liabilities				27,196
Increase (decrease) due to changes in accounting policy required by IFRS 9 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Financial assets at fair value through profit or loss, non-current				4,135,207
Available-for-sale financial assets, non-current				(4,135,207)
Increase (decrease) accumulated other comprehensive income				2,344,772
Increase (decrease) in other equity interest		(2,344,772)
Accounts receivable				(8,370)
Other receivables				$ (1,204)
Increase (decrease) in retained earnings		$ (9,574)
Increase (decrease) due to changes in accounting policy required by IFRS15 [member]
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Increase (decrease) in retained earnings	$ 147,771
Contract asset	901,479
Increase (decrease) in contract assets	865,322
Increase (decrease) in work-in-process inventories	(717,551)
Contract liabilities - current	12,128
Other current liabilities - other	$ 316,391

Summary of Significant Accoun79

Summary of Significant Accounting Policies - Summary of Consolidated Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
SPIL (B.V.I.) Holding Limited [member]
Disclosure of subsidiaries [line items]
Name of investor	The Company
Main operating activities	Investment activities
% of ownership held by the named investors	100.00%	100.00%
Siliconware Investment Co., Ltd [member]
Disclosure of subsidiaries [line items]
Name of investor	The Company
Main operating activities	Investment activities
% of ownership held by the named investors	100.00%	100.00%
Siliconware USA, Inc. [member]
Disclosure of subsidiaries [line items]
Name of investor	SPIL (B.V.I.) Holding Limited
Main operating activities	Communications and relationship maintenance with companies headquartered in North America
% of ownership held by the named investors	100.00%	100.00%
SPIL (Cayman) Holding Limited [member]
Disclosure of subsidiaries [line items]
Name of investor	SPIL (B.V.I.) Holding Limited
Main operating activities	Investment activities
% of ownership held by the named investors	100.00%	100.00%
Siliconware Technology (Suzhou) Limited [member]
Disclosure of subsidiaries [line items]
Name of investor	SPIL (Cayman) Holding Limited
Main operating activities	Assembly and testing services
% of ownership held by the named investors	100.00%	100.00%
Siliconware Electronics (Fujian) Co., Limited [member]
Disclosure of subsidiaries [line items]
Name of investor	SPIL (Cayman) Holding Limited
Main operating activities	Assembly and testing services
% of ownership held by the named investors	100.00%	0.00%

Summary of Significant Accoun80

Summary of Significant Accounting Policies - Summary of Consolidated Subsidiaries (Parenthetical) (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of subsidiaries [line items]
Initial capital amount	$ 1,051,404	$ 31,163,611	$ 31,163,611
Siliconware Electronics (Fujian) Co., Limited [member]
Disclosure of subsidiaries [line items]
Initial capital amount	$ 45,000

Summary of Significant Accoun81

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure of significant accounting policies [line items]
Foreign currency exchange rate, per US$	29.64
Tax estimated and recognized as percentage of undistributed earnings when income is earned	10.00%
Software [member]
Disclosure of significant accounting policies [line items]
Useful lives of intangible assets	3 years

Summary of Significant Accoun82

Summary of Significant Accounting Policies - Summary of Estimated Useful Lives of Property Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	20 years
Buildings [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	55 years
Construction and Improvements [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	3 years
Construction and Improvements [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	15 years
Machinery and equipment [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	5 years
Machinery and equipment [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	6 years
Other equipment [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	2 years
Other equipment [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	6 years

Cash and Cash Equivalents - Sum

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Subclassifications of assets, liabilities and equities [abstract]
Cash on hand and petty cash		$ 1,340		$ 1,072
Savings accounts and checking accounts		5,754,845		3,876,568
Time deposits		18,687,898		20,598,630
Cash and cash equivalents	$ 824,699	$ 24,444,083	$ 825,785	$ 24,476,270	$ 25,191,374	$ 30,154,713

Accounts Receivable, Net - Summ

Accounts Receivable, Net - Summary of Accounts Receivable Net (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of financial assets [line items]
Accounts receivable	$ 568,863	$ 16,861,111	$ 17,354,883
Gross carrying amount [member]
Disclosure of financial assets [line items]
Accounts receivable		16,873,044	17,359,584
Allowance for sale discounts [member]
Disclosure of financial assets [line items]
Accounts receivable		0	(3,006)
Allowance for doubtful accounts [member]
Disclosure of financial assets [line items]
Accounts receivable		$ (11,933)	$ (1,695)	$ (1,695)

Accounts Receivable, Net - Su85

Accounts Receivable, Net - Summary of Movements of Allowance for Doubtful Accounts (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets [line items]
Balance as of January 1		$ (17,354,883)
Balance at January 1 and December 31	$ (568,863)	(16,861,111)	$ (17,354,883)
Allowance for doubtful accounts [member]
Disclosure of financial assets [line items]
Balance as of January 1		1,695	1,695
Allowance for doubtful accounts		11,911	0
Write-offs		(1,673)	0
Balance at January 1 and December 31		$ 11,933	$ 1,695

Inventories - Summary of Invent

Inventories - Summary of Inventory (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Classes of current inventories [abstract]
Raw materials and supplies		$ 5,406,131	$ 5,885,054
Work in process		717,551	613,778
Inventories	$ 206,602	$ 6,123,682	$ 6,498,832

Inventories - Summary of Inve87

Inventories - Summary of Inventory Amounts Recognized in Profit or Loss (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Classes of current inventories [abstract]
Cost of goods sold		$ 66,696,160	$ 65,744,357	$ 61,196,890
Decline in market value and loss on obsolescence		69,848	54,853	20,320
Others		(25,718)	(37,019)	13,412
Amounts recognized in profit or loss	$ 2,251,697	$ 66,740,290	$ 65,762,191	$ 61,230,622

Non-current Assets Held for S88

Non-current Assets Held for Sales - Summary of Non-current Assets Held for Sales (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Subclassifications of assets, liabilities and equities [abstract]
Plant held for sale	$ 0	$ 0	$ 387,503

Non-current Assets Held for S89

Non-current Assets Held for Sales - Additional Information (Detail) $ in Thousands, $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2017TWD ($)	Mar. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Subclassifications of assets, liabilities and equities [abstract]
Consideration on transfer completed	$ 412,000
Gains on disposal of non-current assets held for sales		$ 19,402	$ 655	$ 19,402	$ 0	$ 0

Available-for-sale Financial 90

Available-for-sale Financial Assets - Summary of Available-for-sale Financial Assets (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets [line items]
Available-for-sale financial assets, current	$ 0	$ 0	$ 178,176
Available-for-sale financial assets, non-current	$ 139,515	4,135,207	3,615,658
Common Stock [member]
Disclosure of financial assets [line items]
Available-for-sale financial assets, non-current		4,135,207	3,087,019
Fund [member]
Disclosure of financial assets [line items]
Available-for-sale financial assets, current		0	178,176
Depositary Shares [member]
Disclosure of financial assets [line items]
Available-for-sale financial assets, non-current		$ 0	$ 528,639

Available-for-sale Financial 91

Available-for-sale Financial Assets - Additional Information (Detail) $ / shares in Units, $ in Thousands, $ in Thousands	Oct. 31, 2016TWD ($)shares	Oct. 31, 2016$ / sharesshares	Feb. 29, 2016TWD ($)	Mar. 31, 2017TWD ($)	Sep. 30, 2016TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of financial assets [line items]
Gains on disposal of investments			$ 10,256	$ 53,053	$ 206,943	$ 1,868	$ 55,369	$ 217,199	$ 127,291
Impairment loss due to decline in stock price						0	0	0	1,856,442
Premium from the merger						$ 0	$ 0	$ 51,923	$ 0
ChipMOS Technologies Inc., [member]
Disclosure of financial assets [line items]
Cash to be received for each share exchanged as per merger agreement | $ / shares		$ 3.71
Number of shares received for each share as per merger agreement	0.9355	0.9355
Number of common shares to be issued for each American Depository Shares(ADS)	20	20
Premium from the merger | $	$ 51,923

Investments Accounted for Usi92

Investments Accounted for Using Equity Method - Summary of Significant Investments in Associates (Detail) $ in Thousands, $ in Thousands	1 Months Ended	5 Months Ended	7 Months Ended	12 Months Ended
	Jun. 30, 2017	May 31, 2017	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of associates [line items]
Carrying Amount			$ 97,761	$ 97,761	$ 2,401,531	$ 2,897,644
Yann Yuan Investment Co., Ltd [member]
Disclosure of associates [line items]
Registration				Taiwan, R.O.C.
Carrying Amount					$ 2,383,512	$ 2,897,644	$ 2,400,000
% of ownership interest	32.21%			32.21%	33.33%
ASM Advanced Packaging Materials Pte. Ltd. [member]
Disclosure of associates [line items]
Registration				Singapore
Carrying Amount					$ 18,019
% of ownership interest		39.00%	13.70%		39.00%

Investments Accounted for Usi93

Investments Accounted for Using Equity Method - Additional Information (Detail) $ in Thousands, $ in Thousands	1 Months Ended			3 Months Ended			5 Months Ended	7 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2017TWD ($)shares	Feb. 29, 2016TWD ($)	Oct. 31, 2015TWD ($)	Jun. 30, 2017TWD ($)shares	Mar. 31, 2017TWD ($)	Sep. 30, 2016TWD ($)	May 31, 2017	Dec. 31, 2017USD ($)	Sep. 30, 2015TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)shares	Dec. 31, 2015TWD ($)	Dec. 31, 2017TWD ($)
Disclosure of associates [line items]
Gains on disposal of investments		$ 10,256			$ 53,053	$ 206,943				$ 1,868	$ 55,369	$ 217,199	$ 127,291
Investment accounted for using equity method								$ 97,761		97,761		2,401,531		$ 2,897,644
Gains on reversal of impairment loss of non-financial assets										$ 0	$ 0	$ 0	134,992
Yann Yuan Investment Co., Ltd [member]
Disclosure of associates [line items]
Percentage of ownership	32.21%									32.21%	32.21%	33.33%
Decrease of net equity on associate	$ 6,645			$ 6,645
Interest previously recognized as other comprehensive gains and losses reclassified to investment disposal gains	$ 10,425
Investment accounted for using equity method												$ 2,383,512	2,400,000	$ 2,897,644
Shares of SPIL's common stock held by associate | shares	45,900,000			45,900,000								45,900,000
ASM Advanced Packaging Materials Pte. Ltd. [member]
Disclosure of associates [line items]
Percentage of ownership							39.00%	13.70%				39.00%
Investment accounted for using equity method												$ 18,019
Carrying amount of investment					$ 0								$ 137,011
Interest distributed as capital return			39.00%										39.00%
Recognized disposal loss				$ 1,464
ACSIP Technology Corp [member]
Disclosure of associates [line items]
Gains on disposal of investments													$ 1,059
Interconnect [member]
Disclosure of associates [line items]
Carrying amount of investment									$ 0
Unrecognized share of loss due to sustained losses									$ 133,583
Gains on reversal of impairment loss of non-financial assets			$ 134,992
Recognized share of loss due to sustained losses			(133,583)
Gains on disposal of investments			$ 139,567										$ 139,567
Interconnect [member] | ASM Advanced Packaging Materials Pte. Ltd. [member]
Disclosure of associates [line items]
Proportion of ownership interest acquired			39.00%
Third Party Shareholder [Member] | ASM Advanced Packaging Materials Pte. Ltd. [member]
Disclosure of associates [line items]
Proportion of ownership interest acquired			61.00%

Investments Accounted for Usi94

Investments Accounted for Using Equity Method - Summary of the Analysis of Other Comprehensive Income by Item (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of associates [line items]
Net (loss) income	$ 2,498	$ 74,035	$ 3,221	$ (183,708)
Aggregated individually immaterial associates [member]
Disclosure of associates [line items]
Net (loss) income		74,035	3,221	(183,708)
Other comprehensive income (loss)		380,631	(112,797)	1,304
Total comprehensive income (loss)		$ 454,666	$ (109,576)	$ (182,404)

Financial Instruments by Cate95

Financial Instruments by Category - Summary of Financial Instruments by Category (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2014TWD ($)
Financial Assets
Cash and cash equivalents	$ 824,699	$ 24,444,083	$ 825,785	$ 24,476,270	$ 25,191,374	$ 30,154,713
Notes receivable	536	15,879		23,591
Accounts receivable	568,863	16,861,111		17,354,883
Other receivables	16,602	492,081		581,630
Time deposit pledged as collateral (shown as other current assets-other)		392,100		357,400
Refundable deposit (shown as other non-current assets-other)		666,936		501,924
Available-for-sale financial assets, current	0	0		178,176
Available-for-sale financial assets, non-current	139,515	4,135,207		3,615,658
Financial assets		47,007,397		47,089,532
Financial Liabilities
Short-term loans	115,466	3,422,400		2,741,250
Accounts payable	251,585	7,456,974		8,194,647
Other payables	340,172	10,082,704		11,896,517
Receipts under custody (shown as other current liabilities-other)		74,149		76,231
Deposit received (shown as other current liabilities-other and other non-current liabilities)		60,499		38,907
Convertible bonds (including the current portion)		12,015,229		12,712,651
Long-term loans (including the current portion)		15,840,000		18,340,747
Long-term payable (shown as other non-current liabilities)		5,052		63,215
Financial liability at fair value through profit or loss	$ 27,316	809,640		773,908
Financial liabilities		$ 49,766,647		$ 54,838,073

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		$ 65,380,409
Depreciation expense	$ 486,369	14,415,980	$ 12,905,830	$ 12,903,772
Impairment losses	2,977	88,231	91,247	64,996
Ending balance	$ 2,105,198	62,398,065	65,380,409
Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		126,411,120	121,250,195	115,263,668
Additions		11,738,083	15,247,544	14,009,988
Disposals		(3,682,028)	(8,002,474)	(7,684,033)
Transfers		0	(670,656)	0
Exchange differences, net		(314,634)	(1,413,489)	(339,428)
Ending balance		134,152,541	126,411,120	121,250,195
Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		61,030,711	56,944,587	51,742,997
Depreciation expense		14,415,980	12,905,830	12,903,772
Impairment losses		88,231	91,247	64,996
Disposals		(3,614,591)	(7,902,525)	(7,600,984)
Transfers		0	(284,613)	0
Exchange differences, net		(165,855)	(723,815)	(166,194)
Ending balance		71,754,476	61,030,711	56,944,587
Land [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		2,903,192
Ending balance		2,903,192	2,903,192
Land [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		2,903,192	2,903,192	2,903,192
Additions		0	0	0
Disposals		0	0	0
Transfers		0	0	0
Exchange differences, net		0	0	0
Ending balance		2,903,192	2,903,192	2,903,192
Buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		19,939,679
Ending balance		21,859,531	19,939,679
Buildings [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		32,523,010	30,952,914	22,789,352
Additions		1,376,617	1,445,512	1,423,338
Disposals		0	(83,778)	0
Transfers		2,422,828	428,540	6,798,051
Exchange differences, net		(51,686)	(220,178)	(57,827)
Ending balance		36,270,769	32,523,010	30,952,914
Buildings [member] | Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		12,583,331	11,288,984	9,636,672
Depreciation expense		1,841,411	1,715,407	1,665,873
Impairment losses		0	0	0
Disposals		0	(83,778)	0
Transfers		0	(278,570)	0
Exchange differences, net		(13,504)	(58,712)	(13,561)
Ending balance		14,411,238	12,583,331	11,288,984
Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		32,145,342
Ending balance		30,536,886	32,145,342
Machinery and equipment [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		75,575,254	74,384,223	71,922,606
Additions		6,938,086	7,815,011	7,675,210
Disposals		(3,217,594)	(7,204,489)	(7,055,018)
Transfers		2,562,020	1,542,650	2,074,177
Exchange differences, net		(198,414)	(962,141)	(232,752)
Ending balance		81,659,352	75,575,254	74,384,223
Machinery and equipment [member] | Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		43,429,912	41,253,466	38,233,303
Depreciation expense		10,936,614	9,849,149	10,086,128
Impairment losses		78,468	72,655	46,198
Disposals		(3,179,598)	(7,155,398)	(6,977,590)
Transfers		(8,178)	3,407	966
Exchange differences, net		(134,752)	(593,367)	(135,539)
Ending balance		51,122,466	43,429,912	41,253,466
Other equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		4,674,862
Ending balance		4,691,122	4,674,862
Other equipment [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		9,692,330	8,900,324	7,629,873
Additions		1,236,677	1,283,475	1,192,144
Disposals		(464,434)	(713,787)	(629,015)
Transfers		475,464	342,751	737,087
Exchange differences, net		(28,143)	(120,433)	(29,765)
Ending balance		10,911,894	9,692,330	8,900,324
Other equipment [member] | Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		5,017,468	4,402,137	3,873,022
Depreciation expense		1,637,955	1,341,274	1,151,771
Impairment losses		9,763	18,592	18,798
Disposals		(434,993)	(663,349)	(623,394)
Transfers		8,178	(9,450)	(966)
Exchange differences, net		(17,599)	(71,736)	(17,094)
Ending balance		6,220,772	5,017,468	4,402,137
Construction in progress and equipment awaiting for inspection [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		5,717,334
Ending balance		2,407,334	5,717,334
Construction in progress and equipment awaiting for inspection [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		5,717,334	4,109,542	10,018,645
Additions		2,186,703	4,703,546	3,719,296
Disposals		0	(420)	0
Transfers		(5,460,312)	(2,984,597)	(9,609,315)
Exchange differences, net		(36,391)	(110,737)	(19,084)
Ending balance		$ 2,407,334	$ 5,717,334	$ 4,109,542

Property, Plant and Equipment97

Property, Plant and Equipment - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about financial instruments [line items]
Interest capitalized		$ 0	$ 0	$ 0
Recognized impairment loss	$ 2,977	88,231	91,247	64,996
Gross carrying amount [member]
Disclosure of detailed information about financial instruments [line items]
Reclassified the plant held for sale as non-current assets held for sale			670,656
Accumulated depreciation and impairment [member]
Disclosure of detailed information about financial instruments [line items]
Recognized impairment loss		$ 88,231	91,247	$ 64,996
Reclassified the plant held for sale as non-current assets held for sale			$ 284,613

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about intangible assets [line items]
Beginning balance		$ 175,862
Ending balance	$ 4,024	119,268	$ 175,862
License fee [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		31,460
Ending balance		18,443	31,460
Software [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		144,402
Ending balance		100,825	144,402
Accumulated amortization [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		171,219	121,788	$ 533,826
Additions		85,548	86,725	168,804
Disposals		(98,783)	(36,674)	(580,716)
Exchange differences, net		(144)	(620)	(126)
Ending balance		157,840	171,219	121,788
Accumulated amortization [member] | License fee [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		76,434	58,679	433,876
Additions		13,017	22,109	120,693
Disposals		(75,094)	(4,354)	(495,890)
Exchange differences, net		0	0	0
Ending balance		14,357	76,434	58,679
Accumulated amortization [member] | Software [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		94,785	63,109	99,950
Additions		72,531	64,616	48,111
Disposals		(23,689)	(32,320)	(84,826)
Exchange differences, net		(144)	(620)	(126)
Ending balance		143,483	94,785	63,109
Gross carrying amount [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		347,081	314,562	782,996
Additions		29,237	71,011	112,692
Disposals		(98,783)	(36,674)	(580,716)
Exchange differences, net		(427)	(1,818)	(410)
Ending balance		277,108	347,081	314,562
Gross carrying amount [member] | License fee [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		107,894	112,248	608,138
Additions		0	0	0
Disposals		(75,094)	(4,354)	(495,890)
Exchange differences, net		0	0	0
Ending balance		32,800	107,894	112,248
Gross carrying amount [member] | Software [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		239,187	202,314	174,858
Additions		29,237	71,011	112,692
Disposals		(23,689)	(32,320)	(84,826)
Exchange differences, net		(427)	(1,818)	(410)
Ending balance		$ 244,308	$ 239,187	$ 202,314

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating costs [member]
Disclosure of detailed information about intangible assets [line items]
Amortization of intangible assets	$ 26,100	$ 24,539	$ 14,208
Operating expenses [member]
Disclosure of detailed information about intangible assets [line items]
Amortization of intangible assets	$ 59,448	$ 62,186	$ 154,596

Financial Liabilities at Fai100

Financial Liabilities at Fair Value Through Profit or Loss - Summary of Financial Liabilities at Fair Value through Profit or Loss (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Designated financial liabilities at fair value through profit or loss [abstract]
Conversion option, redemption option and put option of convertible bonds upon initial recognition		$ 774,319	$ 774,319
Valuation adjustments		35,321	(411)
Financial liabilities at fair value through profit or loss	$ 27,316	$ 809,640	$ 773,908

Financial Liabilities at Fai101

Financial Liabilities at Fair Value Through Profit or Loss - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Designated financial liabilities at fair value through profit or loss [abstract]
Gains (losses) on financial liabilities at fair value through profit or loss	$ (1,206)	$ (35,732)	$ 1,025,012	$ (703,368)

Other Payables - Schedule of Ot

Other Payables - Schedule of Other Payables (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Subclassifications of assets, liabilities and equities [abstract]
Payables for equipment		$ 2,234,142	$ 3,486,635
Payables for employees' compensations		3,476,527	3,880,980
Others		4,372,035	4,528,902
Other payables	$ 340,172	$ 10,082,704	$ 11,896,517

Convertible Bonds - Summary of

Convertible Bonds - Summary of Convertible Bonds (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Convertible bonds		$ 12,015,229	$ 12,712,651
Current portion	$ 0	0	(12,712,651)
Total convertible bonds	$ 405,372	12,015,229	0
Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Convertible bonds		12,533,316	13,580,212
Discounts on bonds payable [member]
Disclosure of detailed information about borrowings [line items]
Convertible bonds		$ (518,087)	$ (867,561)

Convertible Bonds - Additional

Convertible Bonds - Additional Information (Detail) $ / shares in Units, $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2014USD ($)$ / $$ / shares	Dec. 31, 2017TWD ($)	Dec. 31, 2017TWD ($)$ / shares	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Oct. 31, 2014TWD ($)$ / $
Disclosure of detailed information about borrowings [line items]
Unsecured overseas convertible bonds issued		$ 12,015,229	$ 12,015,229	$ 12,712,651
Foreign exchange rate		29.64	29.64
Unsecured overseas convertible bonds [member]
Disclosure of detailed information about borrowings [line items]
Unsecured overseas convertible bonds issued	$ 400,000,000
Unsecured overseas convertible bonds maturity	5 years
Coupon interest rate	0.00%
Unsecured overseas convertible bonds par value	$ 250,000
Unsecured overseas convertible bonds conversions price | (per share)	$ 53.1038		$ 44.1443
Foreign exchange rate | $ / $	30.392					30.392
Bond redemption percentage at maturity		105.11%
Description of principal amount repurchase by holder		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) at 103.04% of the principal amount on the third anniversary of the issuance date or (2) at principal amount plus 1% interest compounded semiannually ("Early Redemption Amount") in the event of a change in control or delisting.
Description of terms and conditions of bond redemptions		The Company may redeem the Bonds in whole or in part, from 3 years after the issuance date, at a price equal to the Early Redemption Amount, provided that the closing price of the Company's common shares on the Taiwan Stock Exchange, converted into US dollars at the prevailing exchange rate, on 20 trading days within a period of 30 consecutive trading days, is at least 130% of the Early Redemption Amount divided by the conversion ratio. The Company may, in whole but not in part, redeem all of the Bonds at the Early Redemption Amount in the event that more than 90% of the Bonds have been previously redeemed, converted, or repurchased or cancelled, or in the event of changes in the R.O.C.’s tax rules which result in significant unfavorable tax consequences to the Company.
Aggregate fair value of bond options						$ 774,319
Effective interest rate of debt host contract	2.407%					2.407%
Interest expenses on corporate bonds payable		$ 289,671		$ 306,423	$ 300,672
Unsecured overseas convertible bonds [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Minimum vesting period of bonds		3 years

Loans - Summary of Short-term L

Loans - Summary of Short-term Loans (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Credit loans	$ 115,466	$ 3,422,400	$ 2,741,250
Short-term Loans [Member]
Disclosure of detailed information about borrowings [line items]
Credit loans		$ 3,422,400	$ 2,741,250
Bottom of range [member] | Short-term Loans [Member]
Disclosure of detailed information about borrowings [line items]
Interest rates	1.6764%	1.6764%	1.325%
Top of range [member] | Short-term Loans [Member]
Disclosure of detailed information about borrowings [line items]
Interest rates	2.5112%	2.5112%	1.644%

Loans - Summary of Long-term Lo

Loans - Summary of Long-term Loans (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 15,840,000		$ 18,340,747
Current portion	$ (107,062)	(3,173,333)		(3,500,747)
Long-term loans	$ 427,350	$ 12,666,667		$ 14,840,000
Long-term loans [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Interest rate	1.1358%	1.1358%	1.1287%	1.1287%
Long-term loans [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Interest rate	2.389%	2.389%	2.389%	2.389%
Gross carrying amount [member] | Syndicated bank loans 2012.08.10 - 2017.08.10 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans			$ 33,333	$ 2,162,333
Gross carrying amount [member] | Other bank loans 2013.12.31 - 2016.12.31 Extended to 2019.12.30, Repayables in 3 semi-annually installments starting from December 28, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 2,500,000		1,500,000
Gross carrying amount [member] | Other bank loans 2014.08.11 - 2018.12.13 Repayables in 5 Semi-annually Installments Starting from December 13, 2016 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		340,000		680,000
Gross carrying amount [member] | Other bank loans 2014.08.11 - 2018.12.10 Repayables in 6 Semi-annually Installments Starting from June 13, 2016 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		500,000		1,000,000
Gross carrying amount [member] | Other bank loans 2014.08.11 - 2019.08.11 Repayables in 6 Semi-annually Installments Starting from February 10, 2017 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		1,000,000		1,500,000
Gross carrying amount [member] | Other bank loans 2015.07.01 - 2020.07.01 Repayables in 6 Semi-annually Installments Starting from January 2, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		1,500,000		1,500,000
Gross carrying amount [member] | Other bank loans 2015.11.13 - 2020.11.13 Repayables in 6 Semi-annually Installments Starting from May 11, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		1,000,000		1,000,000
Gross carrying amount [member] | Other bank loans 2016.07.19 - 2021.01.10 Repayables in 6 Semi-annually Installments Starting from July 10, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		3,000,000		3,000,000
Gross carrying amount [member] | Other bank loans 2016.07.19 - 2021.07.19 Repayables in 6 Semi-annually Installments Starting from January 18, 2019 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		4,000,000		4,000,000
Gross carrying amount [member] | Other bank loans 2016.12.30 - 2021.12.30 Repayables in 6 Semi-annually Installments Starting from June 28, 2019 [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 2,000,000		2,000,000
Arrangement fee of syndicated loans [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans				$ (1,586)

Loans - Summary of Long-term107

Loans - Summary of Long-term Loans (Parenthetical) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 15,840,000				$ 18,340,747
Increase in loan on 2017.01.19	$ 33,738	$ 1,000,000	$ 9,000,000	$ 2,500,000
Syndicated bank loans 2012.08.10 - 2017.08.10 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from February 2015	Repayables in 6 semi-annually installments starting from February 2015
Syndicated bank loans 2012.08.10 - 2017.08.10 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Aug. 10, 2012	Aug. 10, 2012
Syndicated bank loans 2012.08.10 - 2017.08.10 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Aug. 10, 2017	Aug. 10, 2017
Syndicated bank loans 2012.08.10 - 2017.08.10 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans					$ 33,333	2,162,333
Other bank loans 2013.12.31 - 2016.12.31 Extended to 2019.12.30, Repayables in 3 semi-annually installments starting from December 28, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Extended to 2019.12.30, and increased by $1,000,000 on 2017.01.19. Repayables in 3 semi-annually installments starting from December 28, 2018	Extended to 2019.12.30, and increased by $1,000,000 on 2017.01.19. Repayables in 3 semi-annually installments starting from December 28, 2018
Increase in loan on 2017.01.19		$ 1,000,000
Other bank loans 2013.12.31 - 2016.12.31 Extended to 2019.12.30, Repayables in 3 semi-annually installments starting from December 28, 2018 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Dec. 31, 2013	Dec. 31, 2013
Other bank loans 2013.12.31 - 2016.12.31 Extended to 2019.12.30, Repayables in 3 semi-annually installments starting from December 28, 2018 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Dec. 31, 2016	Dec. 31, 2016
Other bank loans 2013.12.31 - 2016.12.31 Extended to 2019.12.30, Repayables in 3 semi-annually installments starting from December 28, 2018 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 2,500,000				1,500,000
Other bank loans 2014.08.11 - 2018.12.13 Repayables in 5 Semi-annually Installments Starting from December 13, 2016 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 5 semi-annually installments starting from December 13, 2016	Repayables in 5 semi-annually installments starting from December 13, 2016
Other bank loans 2014.08.11 - 2018.12.13 Repayables in 5 Semi-annually Installments Starting from December 13, 2016 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Aug. 11, 2014	Aug. 11, 2014
Other bank loans 2014.08.11 - 2018.12.13 Repayables in 5 Semi-annually Installments Starting from December 13, 2016 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Dec. 13, 2018	Dec. 13, 2018
Other bank loans 2014.08.11 - 2018.12.13 Repayables in 5 Semi-annually Installments Starting from December 13, 2016 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 340,000				680,000
Other bank loans 2014.08.11 - 2018.12.10 Repayables in 6 Semi-annually Installments Starting from June 13, 2016 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from June 13, 2016	Repayables in 6 semi-annually installments starting from June 13, 2016
Other bank loans 2014.08.11 - 2018.12.10 Repayables in 6 Semi-annually Installments Starting from June 13, 2016 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Aug. 11, 2014	Aug. 11, 2014
Other bank loans 2014.08.11 - 2018.12.10 Repayables in 6 Semi-annually Installments Starting from June 13, 2016 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Dec. 10, 2018	Dec. 10, 2018
Other bank loans 2014.08.11 - 2018.12.10 Repayables in 6 Semi-annually Installments Starting from June 13, 2016 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 500,000				1,000,000
Other bank loans 2014.08.11 - 2019.08.11 Repayables in 6 Semi-annually Installments Starting from February 10, 2017 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installmentsstarting from February 10, 2017	Repayables in 6 semi-annually installmentsstarting from February 10, 2017
Other bank loans 2014.08.11 - 2019.08.11 Repayables in 6 Semi-annually Installments Starting from February 10, 2017 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Aug. 11, 2014	Aug. 11, 2014
Other bank loans 2014.08.11 - 2019.08.11 Repayables in 6 Semi-annually Installments Starting from February 10, 2017 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Aug. 11, 2019	Aug. 11, 2019
Other bank loans 2014.08.11 - 2019.08.11 Repayables in 6 Semi-annually Installments Starting from February 10, 2017 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 1,000,000				1,500,000
Other bank loans 2015.07.01 - 2020.07.01 Repayables in 6 Semi-annually Installments Starting from January 2, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from January 2, 2018	Repayables in 6 semi-annually installments starting from January 2, 2018
Other bank loans 2015.07.01 - 2020.07.01 Repayables in 6 Semi-annually Installments Starting from January 2, 2018 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Jul. 1, 2015	Jul. 1, 2015
Other bank loans 2015.07.01 - 2020.07.01 Repayables in 6 Semi-annually Installments Starting from January 2, 2018 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Jul. 1, 2020	Jul. 1, 2020
Other bank loans 2015.07.01 - 2020.07.01 Repayables in 6 Semi-annually Installments Starting from January 2, 2018 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 1,500,000				1,500,000
Other bank loans 2015.11.13 - 2020.11.13 Repayables in 6 Semi-annually Installments Starting from May 11, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from May 11, 2018	Repayables in 6 semi-annually installments starting from May 11, 2018
Other bank loans 2015.11.13 - 2020.11.13 Repayables in 6 Semi-annually Installments Starting from May 11, 2018 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Nov. 13, 2015	Nov. 13, 2015
Other bank loans 2015.11.13 - 2020.11.13 Repayables in 6 Semi-annually Installments Starting from May 11, 2018 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Nov. 13, 2020	Nov. 13, 2020
Other bank loans 2015.11.13 - 2020.11.13 Repayables in 6 Semi-annually Installments Starting from May 11, 2018 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 1,000,000				1,000,000
Other bank loans 2016.07.19 - 2021.01.10 Repayables in 6 Semi-annually Installments Starting from July 10, 2018 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from July 10, 2018	Repayables in 6 semi-annually installments starting from July 10, 2018
Other bank loans 2016.07.19 - 2021.01.10 Repayables in 6 Semi-annually Installments Starting from July 10, 2018 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Jul. 19, 2016	Jul. 19, 2016
Other bank loans 2016.07.19 - 2021.01.10 Repayables in 6 Semi-annually Installments Starting from July 10, 2018 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Jan. 10, 2021	Jan. 10, 2021
Other bank loans 2016.07.19 - 2021.01.10 Repayables in 6 Semi-annually Installments Starting from July 10, 2018 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 3,000,000				3,000,000
Other bank loans 2016.07.19 - 2021.07.19 Repayables in 6 Semi-annually Installments Starting from January 18, 2019 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from January 18, 2018	Repayables in 6 semi-annually installments starting from January 18, 2018
Other bank loans 2016.07.19 - 2021.07.19 Repayables in 6 Semi-annually Installments Starting from January 18, 2019 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Jul. 19, 2016	Jul. 19, 2016
Other bank loans 2016.07.19 - 2021.07.19 Repayables in 6 Semi-annually Installments Starting from January 18, 2019 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Jul. 19, 2021	Jul. 19, 2021
Other bank loans 2016.07.19 - 2021.07.19 Repayables in 6 Semi-annually Installments Starting from January 18, 2019 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 4,000,000				4,000,000
Other bank loans 2016.12.30 - 2021.12.30 Repayables in 6 Semi-annually Installments Starting from June 28, 2019 [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowing period	Repayables in 6 semi-annually installments starting from June 28, 2019	Repayables in 6 semi-annually installments starting from June 28, 2019
Other bank loans 2016.12.30 - 2021.12.30 Repayables in 6 Semi-annually Installments Starting from June 28, 2019 [member] | Bottom of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Dec. 30, 2016	Dec. 30, 2016
Other bank loans 2016.12.30 - 2021.12.30 Repayables in 6 Semi-annually Installments Starting from June 28, 2019 [member] | Top of range [member]
Disclosure of detailed information about borrowings [line items]
Long term borrowings maturity date	Dec. 30, 2021	Dec. 30, 2021
Other bank loans 2016.12.30 - 2021.12.30 Repayables in 6 Semi-annually Installments Starting from June 28, 2019 [member] | Gross carrying amount [member]
Disclosure of detailed information about borrowings [line items]
Long-term Loans		$ 2,000,000				$ 2,000,000

Post-employment Benefit - Addit

Post-employment Benefit - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)yr	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of defined benefit plans [line items]
Percentage of employer contribution to pension fund	2.00%
Estimate of contributions expected to be paid to the pension plan in 2018	$ 50,667
Weighted average duration of defined benefit plan | yr	11.6
Percentage contribution to the employees' individual pension accounts	6.00%
Defined contribution pension plan expenses	$ 731,170	$ 552,706	$ 533,905
Discount rate [member]
Disclosure of defined benefit plans [line items]
Potential increase in principal actuarial assumptions	0.50%	0.50%
Potential decrease in principal actuarial assumptions	0.50%	0.50%
Future salary increase [member]
Disclosure of defined benefit plans [line items]
Potential increase in principal actuarial assumptions	0.50%	0.50%
Potential decrease in principal actuarial assumptions	0.50%	0.50%
Defined benefit plans to executive officer [member]
Disclosure of defined benefit plans [line items]
Pension plan cost of executive officers	$ 596	$ 63,007
Net defined benefit obligations of executive officers	$ 62,222	$ 64,929

Post-employment Benefit - Summa

Post-employment Benefit - Summary of Amounts Arising from the Defined Benefit Obligation Recognized (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of defined benefit plans [abstract]
Present value of defined benefit obligations	$ 2,513,060	$ 2,550,824
Fair value of plan assets	(1,159,337)	(1,177,592)
Net defined benefit liability	$ 1,353,723	$ 1,373,232	$ 1,207,310	$ 1,033,739

Post-employment Benefit - Su110

Post-employment Benefit - Summary of Movements in Net Defined Benefit Liabilities (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [line items]
Beginning balance	$ 1,373,232	$ 1,207,310	$ 1,033,739
Current service cost	17,171	19,165	20,475
Interest expense (income)	20,216	20,687	22,694
Subtotal	37,387	39,852	43,169
Remeasurements:
Experience adjustments	(13,625)	19,709	10,493
Changes in demographic assumptions			18,021
Changes in financial assumptions		149,878	145,514
Return of plan assets (excluding amount included in net interest expense)	6,281	6,297	5,814
Remeasurements	(7,344)	175,884	179,842
Pension fund contribution	(49,552)	(49,814)	(49,440)
Ending balance	1,353,723	1,373,232	1,207,310
Present value of defined benefit obligations [member]
Disclosure of defined benefit plans [line items]
Beginning balance	2,550,824	2,392,281	2,225,935
Current service cost	17,171	19,165	20,475
Interest expense (income)	37,817	41,441	49,670
Subtotal	54,988	60,606	70,145
Remeasurements:
Experience adjustments	(13,625)	19,709	10,493
Changes in demographic assumptions			18,021
Changes in financial assumptions		149,878	145,514
Remeasurements	(13,625)	169,587	174,028
Paid Pension	(79,127)	(71,650)	(77,827)
Ending balance	2,513,060	2,550,824	2,392,281
Fair value of plan assets [member]
Disclosure of defined benefit plans [line items]
Beginning balance	(1,177,592)	(1,184,971)	(1,192,196)
Interest expense (income)	(17,601)	(20,754)	(26,976)
Subtotal	(17,601)	(20,754)	(26,976)
Remeasurements:
Changes in demographic assumptions			0
Changes in financial assumptions		0	0
Return of plan assets (excluding amount included in net interest expense)	6,281	6,297	5,814
Remeasurements	6,281	6,297	5,814
Pension fund contribution	(49,552)	(49,814)	(49,440)
Paid Pension	79,127	71,650	77,827
Ending balance	$ (1,159,337)	$ (1,177,592)	$ (1,184,971)

Post-employment Benefit - Su111

Post-employment Benefit - Summary of Constitution of Fair Value of Plan Assets (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [abstract]
Cash	$ 270,473	$ 268,962
Equity instruments	574,452	580,435
Debt instruments	314,412	328,195
Plan assets at fair value	$ 1,159,337	$ 1,177,592

Post-employment Benefit - Su112

Post-employment Benefit - Summary of Principal Actuarial Assumptions (Detail)	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [abstract]
Discount rate	1.50%	1.50%
Future salary increases	2.25%	2.25%

Post-employment Benefit - Su113

Post-employment Benefit - Summary of Defined Benefit Obligation (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Discount rate [member]
Disclosure of defined benefit plans [line items]
0.5% increase in assumption	$ (139,783)	$ (150,030)
0.5% decrease in assumption	151,499	163,143
Future salary increase [member]
Disclosure of defined benefit plans [line items]
0.5% increase in assumption	149,644	161,138
0.5% decrease in assumption	$ (139,499)	$ (149,723)

Post-employment Benefit - Su114

Post-employment Benefit - Summary of Expected Maturity Analysis of Undiscounted Defined Benefit Obligation (Detail) $ in Thousands	Dec. 31, 2017TWD ($)
Disclosure of defined benefit plans [line items]
Expected maturity analysis of undiscounted defined benefit obligation	$ 3,104,090
Within 1 year [member]
Disclosure of defined benefit plans [line items]
Expected maturity analysis of undiscounted defined benefit obligation	65,895
1- 2 year(s) [member]
Disclosure of defined benefit plans [line items]
Expected maturity analysis of undiscounted defined benefit obligation	73,658
2-3 years [member]
Disclosure of defined benefit plans [line items]
Expected maturity analysis of undiscounted defined benefit obligation	87,648
Over 3 years [member]
Disclosure of defined benefit plans [line items]
Expected maturity analysis of undiscounted defined benefit obligation	$ 2,876,889

Capital Stock - Additional Info

Capital Stock - Additional Information (Detail) $ / shares in Units, $ / shares in Units, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2017TWD ($)$ / sharesshares	Dec. 31, 2016TWD ($)$ / sharesshares
Disclosure of classes of share capital [Line Items]
Authorized capital | $			$ 36,000,000	$ 36,000,000
Paid-in-capital		$ 1,051,404	$ 31,163,611	$ 31,163,611
Par value per share | $ / shares			$ 10	$ 10
Percentage of American Depository shares as common stock outstanding to vote		51.00%	51.00%
Depositary Shares [member]
Disclosure of classes of share capital [Line Items]
Number of shares issued, value | $	$ 1,500,000
Number of shares issued		30,000,000	30,000,000
Number of shares of common stock represented by each ADSs		5	5
Offering price per share | $ / shares		$ 8.49
Number of shares outstanding		35,557,636	35,557,636	37,783,392

Capital Reserve - Additional In

Capital Reserve - Additional Information (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Equity [abstract]
Percentage of capital reserve used to increase the capital limit	10.00%
Distribution of capital reserve		$ 3,116,361
Distribution of capital reserve, per share		$ 1

Retained Earnings - Additional

Retained Earnings - Additional Information (Details) (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Percentage of statutory surplus reserve	10.00%
Reserve balance exceeding percentage of capital stock	25.00%
Percentage of additional corporate income tax on undistributed earnings	10.00%
Undistributed earnings	$ 10,698,848	$ 10,252,276
Shareholders imputation tax credit	$ 873,827	$ 482,903
Percentage of shareholders imputation tax credit	0.00%	10.50%
Accrued additional percentage of tax on undistributed earnings	10.00%
Undistributed earnings tax percentage	10.00%
Noncurrent portion of tax payable	$ 629,353
Bottom of range [member]
Percentage of cash dividend distribution	50.00%

Retained Earnings - Summary of

Retained Earnings - Summary of Distributions (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Equity [abstract]
Provision of Legal reserve	$ 993,316	$ 876,226
Cash dividends	$ 5,453,632	$ 8,725,811
Cash dividends, per share	$ 1.75	$ 2.80

Other Equity Items - Summary of

Other Equity Items - Summary of Other Equity Items (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Beginning balance		$ 65,120,458	$ 69,529,225	$ 70,773,742
Changes in fair value of financial instruments
Changes in fair value of financial instruments, pretax	$ 15,694	465,175	(1,469,105)	(549,845)
Change in fair value of financial instruments, tax		(49,661)	262,359	19,610
Share of other comprehensive income of associates
Share of other comprehensive income of associates, pretax	14,135	418,944	(121,957)	0
Differences in translation - equity method investments
Differences in translation- equity method investments, pretax	(7,636)	(226,323)	(908,801)	(227,905)
Differences in translation- equity method investments, tax		(194)	570	634
Remeasurements of post-employment benefit obligations
Remeasurements of post-employment benefit obligations, pretax	359	10,647	(177,806)	(179,842)
Remeasurements of post-employment benefit obligations, tax		(1,810)	30,227	30,572
Ending balance	$ 2,274,563	67,418,035	65,120,458	69,529,225
Other comprehensive income, unrealized gain on valuation of available-for-sale financial assets [member]
Beginning balance		1,822,158	3,139,880	3,670,115
Changes in fair value of financial instruments
Changes in fair value of financial instruments, pretax		519,549	(1,229,348)	(2,406,287)
Change in fair value of financial instruments, tax		(63,395)	242,555	19,610
Recognition of changes in fair value of financial instruments in profit or loss
Recognition of changes in fair value of financial instruments in profit or loss, pretax		(54,374)	(239,757)	1,856,442
Recognition of changes in fair value of financial instruments in profit or loss, tax		13,734	19,804	0
Share of other comprehensive income of associates
Share of other comprehensive income of associates, pretax		418,944	(121,957)	0
Share of other comprehensive income of associates, tax		(37,721)	10,981	0
Remeasurements of post-employment benefit obligations
Ending balance		2,618,895	1,822,158	3,139,880
Other comprehensive income, exchange difference on translation of foreign financial statements [member]
Beginning balance		(415,249)	492,982	720,253
Differences in translation - equity method investments
Differences in translation- equity method investments, pretax		(227,787)	(908,801)	(223,940)
Differences in translation- equity method investments, tax		111	570	(40)
Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method
Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method, pretax		1,464	0	(3,965)
Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method, tax		(305)	0	674
Remeasurements of post-employment benefit obligations
Ending balance		(641,766)	(415,249)	492,982
Other comprehensive income, remeasurements of post-employment benefit obligations [member]
Beginning balance		(273,510)	(125,931)	23,339
Changes in fair value of financial instruments
Changes in fair value of financial instruments, pretax		0	0	0
Change in fair value of financial instruments, tax		0	0	0
Recognition of changes in fair value of financial instruments in profit or loss
Recognition of changes in fair value of financial instruments in profit or loss, pretax		0	0	0
Recognition of changes in fair value of financial instruments in profit or loss, tax		0	0	0
Share of other comprehensive income of associates
Share of other comprehensive income of associates, pretax		0	0	0
Share of other comprehensive income of associates, tax		0	0	0
Differences in translation - equity method investments
Differences in translation- equity method investments, pretax		0	0	0
Differences in translation- equity method investments, tax		0	0	0
Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method
Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method, pretax		0	0	0
Other comprehensive income/losses reclassified to profit or loss upon disposal of investments accounted for using the equity method, tax		0	0	0
Remeasurements of post-employment benefit obligations
Remeasurements of post-employment benefit obligations, pretax		10,647	(177,806)	(179,842)
Remeasurements of post-employment benefit obligations, tax		(1,810)	30,227	30,572
Ending balance		$ (264,673)	$ (273,510)	$ (125,931)

Expenses by Nature - Summary of

Expenses by Nature - Summary of Employee Benefit Expenses (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee benefit expenses
Salaries and bonuses	$ 15,041,087	$ 16,155,821	$ 15,339,459
Post employment benefits	769,153	655,565	577,074
Directors' remuneration	91,750	127,111	112,801
Others	2,607,597	2,190,194	2,026,237
Employee benefit expenses	18,509,587	19,128,691	18,055,571
Depreciation and amortization expenses	$ 14,625,299	$ 13,291,190	$ 13,513,985

Expenses by Nature - Additional

Expenses by Nature - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expenses by nature [abstract]
Annual profit shared as employee compensation	10.00%
Annual profit shared as director's remuneration	1.00%
Accrued employee compensation (bonus)	$ 917,496	$ 1,271,115	$ 1,128,007
Accrued directors' remuneration	$ 91,750	$ 127,111	$ 112,801

Other Income and Expenses - Sum

Other Income and Expenses - Summary of Other Income and Expenses (Detail) $ in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Material income and expense [abstract]
Loss on damages and claims			$ (120,744)	$ (298,778)	$ (374,613)
Gains on disposal of property, plant and equipment and other assets		$ 5,080	150,579	32,615	31,293
Gains on disposal of non-current assets held for sales	$ 19,402	655	19,402	0	0
Impairment loss on property, plant and equipment		(2,977)	(88,231)	(91,247)	(64,996)
Others			166,040	240,404	152,499
Other income and expense		$ 4,286	$ 127,046	$ (117,006)	$ (255,817)

Other Gains and Losses, Net - S

Other Gains and Losses, Net - Schedule of Other Gains And Losses Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Material income and expense [abstract]
Foreign exchange gain (loss)-net		$ 39,976	$ (104,365)	$ (77,439)
Gains on reversal of impairment loss of non-financial assets	$ 0	0	0	134,992
Other gains and losses, net	$ 1,349	$ 39,976	$ (104,365)	$ 57,553

Income Tax - Income Taxes Recog

Income Tax - Income Taxes Recognized in Profit or Loss (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Current income tax expense
Recognition for the current period		$ 1,188,463	$ 1,356,232	$ 1,741,385
Provision of additional 10% tax on undistributed earnings		982,843	904,395	906,273
Reversal of additional 10% tax on undistributed earnings due to dividend distribution		(904,395)	(788,603)	(1,056,043)
Income tax adjustments for prior years		(6,759)	(6,336)	(39,435)
Current income tax expense		1,260,152	1,465,688	1,552,180
Deferred income tax expense
Temporary differences		265,427	401,511	(186,121)
Income tax expense recognized in profit or loss	$ 51,470	$ 1,525,579	$ 1,867,199	$ 1,366,059

Income Tax - Income Taxes Re125

Income Tax - Income Taxes Recognized in Profit or Loss (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Major components of tax expense (income) [abstract]
Current income tax rate on undistributed earnings	10.00%	10.00%	10.00%
Current income tax rate on reversal of undistributed earnings	10.00%	10.00%	10.00%

Income Tax - Profit Before Tax

Income Tax - Profit Before Tax Differs from the Theoretical Amount that Would Arise using the Weighted Average Tax Rate (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Reconciliation of accounting profit multiplied by applicable tax rates [abstract]
Income tax expense calculated at the statutory tax rates applicable to respective countries		$ 1,783,328	$ 2,300,048	$ 2,057,890
Expense disallowed (deductible income) by tax regulation		(13,203)	113,971	319,835
Tax exempt income by tax regulation		(389,163)	(572,372)	(736,103)
Temporary difference not recognized as deferred income tax liabilities		(135,960)	(156,588)	(179,130)
Change in assessment of realization of deferred income tax assets		0	0	(1,071)
Effect from Alternative Minimum Tax		32,688	72,684	88,944
Provision of additional 10% tax on undistributed earnings		982,843	904,395	906,273
Adjustment: over provision from prior years		(911,703)	(794,939)	(1,090,579)
Deferred tax effect of earnings of subsidiaries		176,749	0	0
Income tax expense recognized in profit or loss	$ 51,470	$ 1,525,579	$ 1,867,199	$ 1,366,059

Income Tax - Profit Before T127

Income Tax - Profit Before Tax Differs from the Theoretical Amount that Would Arise using the Weighted Average Tax Rate (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of accounting profit multiplied by applicable tax rates [abstract]
Taxes provided for repatriated undistributed earnings percentage	10.00%	10.00%	10.00%

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of income tax [line items]
Weighted average statutory tax rates	20.50%	19.70%	19.83%
Percentage of income tax effect on dividend distribution for prior year provisions	10.00%
Change in net income as a result of tax holiday	$ 354,353	$ 488,100
Change in net income per share as a result of tax holiday	$ 0.11	$ 0.16
Applicable tax rate	17.00%
China [member]
Disclosure of income tax [line items]
Applicable tax rate	25.00%

Income Tax - Income Taxes Re129

Income Tax - Income Taxes Recognized In Other Comprehensive Income (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income tax relating to components of other comprehensive income [abstract]
Change in fair value of financial instruments, tax	$ (49,661)	$ 262,359	$ 19,610
Share of other comprehensive income of associates	(37,721)	10,981	0
Exchange difference on translation of foreign financial statements	(194)	570	634
Remeasurements of post-employment benefit obligation	(1,810)	30,227	30,572
Total	$ (89,386)	$ 304,137	$ 50,816

Income Tax - Changes in Deferre

Income Tax - Changes in Deferred Income Tax Assets and Liabilities (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of income tax [line items]
Beginning balance	$ 488,352	$ 577,469	$ 339,894
Profit or Loss	(265,427)	(401,511)	186,121
Other Comprehensive Income	(89,386)	304,137	50,816
Effect of Foreign Currency Exchange Differences	1,611	8,257	638
Ending balance	135,150	488,352	577,469
Deferred Income Tax Assets [Member]
Disclosure of income tax [line items]
Beginning balance	752,712	912,054	696,112
Profit or Loss	(108,929)	(188,248)	185,767
Other Comprehensive Income	(28,745)	30,797	31,206
Effect of Foreign Currency Exchange Differences	(305)	(1,891)	(1,031)
Ending balance	614,733	752,712	912,054
Deferred Income Tax Assets [Member] | Deferred tax assets convertible bonds [member]
Disclosure of income tax [line items]
Beginning balance	232,582	220,754	95,623
Profit or Loss	(120,794)	11,828	125,131
Ending balance	111,788	232,582	220,754
Deferred Income Tax Assets [Member] | Post employment benefit obligations [member]
Disclosure of income tax [line items]
Beginning balance	243,526	193,689	165,371
Profit or Loss	(12,559)	19,610	(2,254)
Other Comprehensive Income	(1,810)	30,227	30,572
Ending balance	229,157	243,526	193,689
Deferred Income Tax Assets [Member] | Unrealized losses on inventories [member]
Disclosure of income tax [line items]
Beginning balance	50,380
Profit or Loss	19,594
Effect of Foreign Currency Exchange Differences	(231)
Ending balance	69,743	50,380
Deferred Income Tax Assets [Member] | Provisions [member]
Disclosure of income tax [line items]
Beginning balance	70,678
Profit or Loss	(29,175)
Ending balance	41,503	70,678
Deferred Income Tax Assets [Member] | Compensated absences payable [member]
Disclosure of income tax [line items]
Beginning balance	69,876
Profit or Loss	3,469
Effect of Foreign Currency Exchange Differences	(36)
Ending balance	73,309	69,876
Deferred Income Tax Assets [Member] | Other temporary differences [member]
Disclosure of income tax [line items]
Beginning balance	274,210	319,077	332,786
Profit or Loss		(43,697)	(13,352)
Other Comprehensive Income		570	634
Effect of Foreign Currency Exchange Differences		(1,740)	(991)
Ending balance		274,210	319,077
Deferred Income Tax Assets [Member] | Other temporary differences [member] | After certain reclassifications [member]
Disclosure of income tax [line items]
Beginning balance	85,670
Profit or Loss	30,536
Other Comprehensive Income	(26,935)
Effect of Foreign Currency Exchange Differences	(38)
Ending balance	89,233	85,670
Deferred Income Tax Assets [Member] | Unrealized sales allowance [member]
Disclosure of income tax [line items]
Beginning balance	2,394	4,352	47,722
Profit or Loss		(1,807)	(43,330)
Effect of Foreign Currency Exchange Differences		(151)	(40)
Ending balance		2,394	4,352
Deferred Income Tax Assets [Member] | Unrealized losses on financial liabilities at fair value through profit or loss [member]
Disclosure of income tax [line items]
Beginning balance	0	174,182	54,610
Profit or Loss		(174,182)	119,572
Other Comprehensive Income		0	0
Effect of Foreign Currency Exchange Differences		0	0
Ending balance		0	174,182
Deferred income tax liabilities [Member]
Disclosure of income tax [line items]
Beginning balance	(264,360)	(334,585)	(356,218)
Profit or Loss	(156,498)	(213,263)	354
Other Comprehensive Income	(60,641)	273,340	19,610
Effect of Foreign Currency Exchange Differences	1,916	10,148	1,669
Ending balance	(479,583)	(264,360)	(334,585)
Deferred income tax liabilities [Member] | Other temporary differences [member]
Disclosure of income tax [line items]
Beginning balance	(61,330)	(43,849)	(60,003)
Profit or Loss	39,678	(33,782)	15,182
Other Comprehensive Income	(10,981)	10,981	0
Effect of Foreign Currency Exchange Differences	697	5,320	972
Ending balance	(31,936)	(61,330)	(43,849)
Deferred income tax liabilities [Member] | Gains from investment for using equity method [member]
Disclosure of income tax [line items]
Beginning balance	0
Profit or Loss	(176,749)
Other Comprehensive Income	0
Effect of Foreign Currency Exchange Differences	0
Ending balance	(176,749)	0
Deferred income tax liabilities [Member] | Unrealized gain on available-for-sale financial assets [member]
Disclosure of income tax [line items]
Beginning balance	(140,514)	(263,038)	(282,648)
Profit or Loss	(21,291)	(139,835)	0
Other Comprehensive Income	(49,660)	262,359	19,610
Ending balance	(211,465)	(140,514)	(263,038)
Deferred income tax liabilities [Member] | Unrealized gain on property, plant and equipment [member]
Disclosure of income tax [line items]
Beginning balance	(62,516)	(27,698)	(13,567)
Profit or Loss	1,864	(39,646)	(14,828)
Effect of Foreign Currency Exchange Differences	1,219	4,828	697
Ending balance	$ (59,433)	$ (62,516)	$ (27,698)

Income Tax - Unrecognized Defer

Income Tax - Unrecognized Deferred Income Tax Liabilities Relating to Taxable Temporary Differences for Investments in Foreign Subsidiaries (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [abstract]
Investment in foreign subsidiaries	$ 7,266,412	$ 6,693,787

Earnings Per Share (EPS) - Sche

Earnings Per Share (EPS) - Schedule of Earnings Per Share (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)$ / sharesshares	Dec. 31, 2017$ / shares	Dec. 31, 2016TWD ($)$ / sharesshares	Dec. 31, 2015TWD ($)$ / sharesshares
Income after tax
Net income | $	$ 7,171,534		$ 9,806,937	$ 9,011,463
Dilutive effect of convertible bonds | $	(549,203)		(779,928)
Diluted earnings per share | $	$ 6,622,331		$ 9,027,009	$ 9,011,463
Weighted average outstanding common stock
Net income	3,116,361		3,116,361	3,116,361
Dilutive effect of employee compensation	22,122		28,643	33,769
Dilutive effect of convertible bonds	275,388		265,677
Diluted earnings per share	3,413,871		3,410,681	3,150,130
Earnings per share
Net income | (per share)	$ 2.30	$ 0.08	$ 3.15	$ 2.89
Diluted earnings per share | (per share)	$ 1.94	$ 0.07	$ 2.65	$ 2.86

Supplemental Cash Flow Infor133

Supplemental Cash Flow Information - Summary of Investing Activities (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Non Cash Transactions [abstract]
Purchase of property, plant and equipment		$ 11,738,083	$ 15,247,544	$ 14,009,988
(Decrease)/ increase in prepayment for equipment		(32,435)	21,754	(4,798)
Decrease/ (increase) in equipment payable, net		1,252,493	89,820	(838,740)
(Increase)/ decrease in notes payable of construction		0	0	699,900
Effect of foreign currency exchange		(25,486)	(63,997)	(10,919)
Cash payment for acquisition of property, plant, and equipment	$ 436,324	$ 12,932,655	$ 15,295,121	$ 13,855,431

Supplemental Cash Flow Infor134

Supplemental Cash Flow Information - Summary of Reconciliation of Liabilities Arising from Financing Activities (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	$ 33,833,555
Cash flows	(1,479,283)
Foreign exchange movement	(1,307,401)
Fair Value Changes	0
Amortization of discount	289,671
Amortization of syndicated loans fee	1,586
Ending balance	31,338,128
Unrealized losses on financial liabilities at fair value through profit or loss [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	773,908
Cash flows	0
Foreign exchange movement	0
Fair Value Changes	35,732
Amortization of discount	0
Amortization of syndicated loans fee	0
Ending balance	809,640
Long-term loans (include the current portion) [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	18,340,747
Cash flows	(2,413,112)
Foreign exchange movement	(89,221)
Fair Value Changes	0
Amortization of discount	0
Amortization of syndicated loans fee	1,586
Ending balance	15,840,000
Short-term loans [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	2,741,250
Cash flows	912,080
Foreign exchange movement	(230,930)
Fair Value Changes	0
Amortization of discount	0
Amortization of syndicated loans fee	0
Ending balance	3,422,400
Convertible bonds (Include the current portion) [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	12,712,651
Cash flows	0
Foreign exchange movement	(987,093)
Fair Value Changes	0
Amortization of discount	289,671
Amortization of syndicated loans fee	0
Ending balance	12,015,229
Refundable deposits [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	38,907
Cash flows	21,749
Foreign exchange movement	(157)
Fair Value Changes	0
Amortization of discount	0
Amortization of syndicated loans fee	0
Ending balance	$ 60,499

Supplemental Cash Flow Infor135

Supplemental Cash Flow Information - Additional Information (Detail) - $ / shares	Oct. 31, 2016	Oct. 31, 2015	Dec. 31, 2015
ASM Advanced Packaging Materials Pte. Ltd. [member]
Disclosure of non cash investing activities [line items]
Interest distributed as capital return		39.00%	39.00%
ChipMOS Technologies Inc., [member]
Disclosure of non cash investing activities [line items]
Cash received for each share in merger agreement	$ 3.71
Number of ADS received for each share in merger agreement	0.9355
Number of common shares for each ADS	20

Supplemental Cash Flow Infor136

Supplemental Cash Flow Information - Summary of Non-Cash Investment Activities (Detail) $ in Thousands, $ in Thousands	Oct. 31, 2016TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)	Dec. 31, 2017TWD ($)
Disclosure of non cash investing activities [line items]
Available- for-sale financial assets, non-current		$ 139,515		$ 3,615,658		$ 4,135,207
Other income		$ 0	$ 0	(51,923)	$ 0
ChipMOS Technologies Inc., [member]
Disclosure of non cash investing activities [line items]
Available- for-sale financial assets, non-current				655,066
Other income	$ (51,923)
ChipMOS Technologies (Bermuda) Ltd. [member]
Disclosure of non cash investing activities [line items]
Decrease in available-for-sale financial assets, non-current				(748,540)
Other income				(51,923)
Increase in other receivables				$ 145,397

Supplemental Cash Flow Infor137

Supplemental Cash Flow Information - Summary of Capital Return (Detail) - TWD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2017	Sep. 30, 2015
Disclosure of non cash investing activities [line items]
Decrease in difference on translation (Show as other equity item)		$ 25,486	$ 63,997	$ 10,919
ASM Advanced Packaging Materials Pte. Ltd. [member]
Disclosure of non cash investing activities [line items]
Acquisition of investments accounted for using the equity method-AAPM				137,011	$ 0
Capital return				0
Interconnect [member]
Disclosure of non cash investing activities [line items]
Acquisition of investments accounted for using the equity method-AAPM						$ 0
Decrease in difference on translation (Show as other equity item)				3,291
Decrease in deferred tax liabilities				674
Decrease in investments accounted for using the equity method				(1,409)
Gains on disposal of investments	$ (139,567)			$ (139,567)

Operating Leases - Additional I

Operating Leases - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of finance lease and operating lease by lessee [abstract]
Rental expense	$ 730,047	$ 662,839	$ 490,132

Related Party Transactions - Sc

Related Party Transactions - Schedule of Transactions Between Company and Other Related Parties (Detail) shares in Thousands, $ in Thousands, $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 29, 2016TWD ($)	Mar. 31, 2017TWD ($)	Sep. 30, 2016TWD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)shares	Dec. 31, 2015TWD ($)	Dec. 31, 2017TWD ($)
Disclosure of transactions between related parties [line items]
Available-for-sale financial assets, non-current				$ 139,515		$ 3,615,658		$ 4,135,207
Gains on disposal of investments	$ 10,256	$ 53,053	$ 206,943	$ 1,868	$ 55,369	$ 217,199	$ 127,291
Associates [member]
Disclosure of transactions between related parties [line items]
Shares | shares						57,810
Available-for-sale financial assets, non-current						$ 376,943
Gains on disposal of investments						$ 206,943

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - Joint share exchange agreement [member] - $ / shares	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Disclosure of transactions between related parties [line items]
Adjusted exchange price per share			$ 51.2
Agreement term		18 months
Advanced Semiconductor Engineering, Inc. [member]
Disclosure of transactions between related parties [line items]
Exchange price for common share	$ 55
Common share exchange ratio	$ 0.5
Restriction period		24 months

Related Party Transactions -141

Related Party Transactions - Schedule of Personnel Compensations to Directors, Supervisors, and Managements (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of transactions between related parties [abstract]
Short-term employee benefits	$ 313,922	$ 443,802	$ 370,943
Post-employment benefits	2,991	65,217	2,866
Personnel compensations	$ 316,913	$ 509,019	$ 373,809

Assets Pledged as Collateral -

Assets Pledged as Collateral - Summary of Assets Pledged as Collateral (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure assets pledged as collateral [abstract]
Time deposits (shown as other current assets- other)	$ 392,100	$ 357,400
Subject of collateral	Guarantees for customs duties and land leased from Science Park Administration

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - 12 months ended Dec. 31, 2017 $ in Thousands, $ in Billions	TWD ($)	USD ($)	TWD ($)
Commitments and contingencies [line items]
Business acquisition		100.00%	100.00%
Business acquisition disposal		100.00%	100.00%
Exclusive licensing of all or material patents or technologies		100.00%	100.00%
Termination fee	$ 17
Significant agreements, amount		$ 1,454,580
Significant agreements, unpaid		$ 144,908
Top of range [member]
Commitments and contingencies [line items]
Assumption of aggregated transaction amount of the entire business or assets from others excluded			$ 0.5

Commitments and Contingencie144

Commitments and Contingencies - Summary of Future Minimum Lease Payments Under Non-cancellable Operating Leases (Detail) $ in Thousands	Dec. 31, 2017TWD ($)
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments	$ 1,100,291
Within 1 year [member]
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments	143,573
1- 5 year(s) [member]
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments	298,888
Over 5 years [member]
Disclosure of finance lease and operating lease by lessee [line items]
Future minimum lease payments	$ 657,830

Significant Event After the 145

Significant Event After the Reporting Period - Additional Information (Detail) ¥ in Thousands, $ in Thousands	1 Months Ended			12 Months Ended
	Feb. 28, 2018TWD ($)	Feb. 28, 2018CNY (¥)	Mar. 31, 2017TWD ($)	Dec. 31, 2018	Dec. 31, 2017
Disclosure of events after reporting period [line items]
Proceeds from ownership interest disposed			$ 412,000
Corporate income tax rate					17.00%
Undistributed earnings rate					10.00%
Disposal of major subsidiary [member] | SPIL (Cayman) Holding Limited [member] | Siliconware Technology (Suzhou) Limited [member]
Disclosure of events after reporting period [line items]
Percentage of ownership disposed in subsidiary	30.00%	30.00%
Proceeds from ownership interest disposed	$ 4,675,542	¥ 1,026,000
Changes in tax rates or tax laws enacted or announced [member]
Disclosure of events after reporting period [line items]
Corporate income tax rate				20.00%
Undistributed earnings rate				5.00%

Financial Risk Management - Sum

Financial Risk Management - Summary of Exposure to Foreign Exchange Risks (Detail) ¥ in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2017JPY (¥)	Dec. 31, 2016USD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2016JPY (¥)
Disclosure of detailed information about financial instruments [line items]
Investments accounted for using the equity method	$ 97,761	$ 2,897,644			$ 2,401,531
Exchange rates	29.64	29.64	29.64
Financial assets		$ 47,007,397			47,089,532
Financial liabilities		$ 49,766,647			$ 54,838,073
Monetary assets [member] | USD:NTD [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates	29.7100	29.7100	29.7100	32.2000	32.2000	32.2000
Sensitivity analysis, Movement	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Sensitivity analysis, Impact to profit and loss before tax		$ 174,850			$ 257,688
Financial assets	$ 588,521			$ 800,272
Monetary assets [member] | USD:RMB [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates	6.5342	6.5342	6.5342	6.9370	6.9370	6.9370
Sensitivity analysis, Movement	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Sensitivity analysis, Impact to profit and loss before tax		$ 12,817			$ 5,727
Financial assets	$ 43,141			$ 17,786
Nonmonetary assets [member] | USD:NTD [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates				32.2000	32.2000	32.2000
Financial assets				$ 21,951
Gains from investment for using equity method [member] | USD:NTD [member]
Disclosure of detailed information about financial instruments [line items]
Investments accounted for using the equity method				$ 559
Exchange rates				32.2500	32.2500	32.2500
Monetary liabilities [member] | USD:NTD [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates	29.8100	29.8100	29.8100	32.3000	32.3000	32.3000
Sensitivity analysis, Movement	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Sensitivity analysis, Impact to profit and loss before tax		$ 164,206			$ 192,721
Financial liabilities	$ 550,842			$ 596,659
Monetary liabilities [member] | USD:RMB [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates	6.5342	6.5342	6.5342	6.9370	6.9370	6.9370
Sensitivity analysis, Movement	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Sensitivity analysis, Impact to profit and loss before tax		$ 47,149			$ 36,589
Financial liabilities	$ 158,166			$ 113,280
Monetary liabilities [member] | JPY:NTD [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates	0.2662	0.2662	0.2662	0.2776	0.2776	0.2776
Sensitivity analysis, Movement	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Sensitivity analysis, Impact to profit and loss before tax		$ 7,754			$ 10,656
Financial liabilities | ¥			¥ 2,912,882			¥ 3,838,753
Monetary liabilities [member] | JPY:RMB [member]
Disclosure of detailed information about financial instruments [line items]
Exchange rates	0.0579	0.0579	0.0579	0.0596	0.0596	0.0596
Sensitivity analysis, Movement	1.00%	1.00%	1.00%	1.00%	1.00%	1.00%
Sensitivity analysis, Impact to profit and loss before tax		$ 2,697			$ 1,656
Financial liabilities | ¥			¥ 1,013,068			¥ 596,668

Financial Risk Management - Add

Financial Risk Management - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017TWD ($)Customers	Dec. 31, 2016TWD ($)Customers
Disclosure of detailed information about financial instruments [line items]
Financial assets	$ 47,007,397	$ 47,089,532
Financial liabilities	$ 49,766,647	$ 54,838,073
Price risk [member]
Disclosure of detailed information about financial instruments [line items]
Percentage of increase/decrease in risk	10.00%	10.00%
Effect of increase/decrease in risk on income before tax/other comprehensive income	$ 413,521	$ 352,579
Interest rate risk [member]
Disclosure of detailed information about financial instruments [line items]
Percentage of increase/decrease in risk	0.10%	0.10%
Effect of increase/decrease in risk on income before tax/other comprehensive income	$ 19,262	$ 21,077
Financial assets	0	6,092
Financial liabilities	$ 19,262,400	$ 21,083,583
Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Number of largest customers | Customers	10	10
Percentage of accounts receivable	67.00%	65.00%

Financial Risk Management - 148

Financial Risk Management - Summary of Aging Analysis of Accounts Receivable (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net	$ 568,863	$ 16,861,111	$ 17,354,883
Financial assets past due [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		1,341,068	994,063
Financial assets past due [member] | 1- 90 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		1,322,342	933,715
Financial assets past due [member] | 91- 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		15,165	54,947
Financial assets past due [member] | Over 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		3,561	5,401
Financial assets impaired [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		11,933	1,695
Financial assets impaired [member] | 1- 90 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		0	0
Financial assets impaired [member] | 91- 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		10,238	0
Financial assets impaired [member] | Over 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		1,695	1,695
Financial assets past due but not impaired [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		1,329,135	992,368
Financial assets past due but not impaired [member] | 1- 90 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		1,322,342	933,715
Financial assets past due but not impaired [member] | 91- 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		4,927	54,947
Financial assets past due but not impaired [member] | Over 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Accounts receivables, net		$ 1,866	$ 3,706

Financial Risk Management - 149

Financial Risk Management - Summary of Aging Analysis of Accounts Receivable (Parenthetical) (Detail) - TWD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial assets that are either past due or impaired [abstract]
Impairment loss on accounts receivable	$ 0	$ 0

Financial Risk Management - 150

Financial Risk Management - Summary of Financial Liabilities (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Short-term Loans	$ 3,454,355	$ 2,761,041
Accounts Payable	7,456,974	8,194,647
Other Payables	10,082,704	11,896,517
Other Current Liabilities - Others	133,212	106,859
Convertible Bonds (include the current portion)	12,533,316	13,312,768
Long-term Loans (include the current portion)	16,228,726	18,928,239
Other Non-Current Liabilities	6,488	71,494
Financial liabilities	49,895,775	55,271,565
Within 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Short-term Loans	3,454,355	2,761,041
Accounts Payable	7,456,974	8,194,647
Other Payables	10,082,704	11,896,517
Other Current Liabilities - Others	133,212	106,859
Convertible Bonds (include the current portion)	0	13,312,768
Long-term Loans (include the current portion)	3,363,170	3,714,850
Other Non-Current Liabilities	0	0
Financial liabilities	24,490,415	39,986,682
1- 2 year(s) [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Short-term Loans	0	0
Accounts Payable	0	0
Other Payables	0	0
Other Current Liabilities - Others	0	0
Convertible Bonds (include the current portion)	12,533,316	0
Long-term Loans (include the current portion)	6,462,779	2,851,419
Other Non-Current Liabilities	5,052	63,215
Financial liabilities	19,001,147	2,914,634
2-3 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Short-term Loans	0	0
Accounts Payable	0	0
Other Payables	0	0
Other Current Liabilities - Others	0	0
Convertible Bonds (include the current portion)	0	0
Long-term Loans (include the current portion)	3,889,463	5,959,549
Other Non-Current Liabilities	208	0
Financial liabilities	3,889,671	5,959,549
Over 3 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Short-term Loans	0	0
Accounts Payable	0	0
Other Payables	0	0
Other Current Liabilities - Others	0	0
Convertible Bonds (include the current portion)	0	0
Long-term Loans (include the current portion)	2,513,314	6,402,421
Other Non-Current Liabilities	1,228	8,279
Financial liabilities	$ 2,514,542	$ 6,410,700

Fair Value Information on Fi151

Fair Value Information on Financial Instruments - Summary of Convertible Bonds (Detail) - TWD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about financial instruments [line items]
Convertible bonds	$ 12,015,229	$ 12,712,651
At fair value [member] | Level 3 [member]
Disclosure of detailed information about financial instruments [line items]
Convertible bonds	$ 12,007,468	$ 12,841,188

Fair Value Information on Fi152

Fair Value Information on Financial Instruments - Summary of Financial Instruments Measured at Fair Value (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)
Disclosure of detailed information about financial instruments [line items]
Financial liability at fair value through profit or loss, current	$ 27,316	$ 809,640	$ 773,908
Recurring fair value measurement [member] | Level 1 [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets		4,135,207	3,615,658
Recurring fair value measurement [member] | Level 2 [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets		0	178,176
Recurring fair value measurement [member] | Level 3 [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets		0	0
Financial liability at fair value through profit or loss, current		$ 809,640	$ 773,908

Fair Value Information on Fi153

Fair Value Information on Financial Instruments - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about financial instruments [line items]
Losses/ (Gains) on financial liabilities at fair value through profit or loss	$ 1,206	$ 35,732	$ (1,025,012)	$ 703,368
Level 3 [member]
Disclosure of detailed information about financial instruments [line items]
Increase in the value of stock market price	10.00%	10.00%	10.00%
Decrease in income before tax as a effect of increase in market price		$ 1,172,129	$ 662,796
Decrease in the value of stock market price	10.00%	10.00%	10.00%
Increase in income before tax as a effect of decrease in market price		$ 808,447	$ 549,100
Increase in the expected volatility	5.00%	5.00%	5.00%
Decrease in income before tax as a effect of Increase in expected volatility		$ 184,822	$ 258,400
Decrease in the expected volatility	5.00%	5.00%	5.00%
Increase in income before tax as a effect of decrease in expected volatility		$ 106,124	$ 276,488
Non-recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [line items]
Volatility	9.72%	9.72%	26.83%
Non-recurring fair value measurement [member] | Level 3 [member]
Disclosure of detailed information about financial instruments [line items]
Losses/ (Gains) on financial liabilities at fair value through profit or loss		$ 35,732	$ (1,025,012)	$ 703,368

Fair Value Information on Fi154

Fair Value Information on Financial Instruments - Summary of Reconciliation of Level 3 Fair Value Measurements of Financial Liabilities (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of detailed information about financial instruments [line items]
Beginning balance		$ 54,838,073
Losses/ (Gains) on financial liabilities at fair value through profit or loss	$ 1,206	35,732	$ (1,025,012)	$ 703,368
Ending balance		49,766,647	54,838,073
Non-recurring fair value measurement [member] | Level 3 [member]
Disclosure of detailed information about financial instruments [line items]
Beginning balance		773,908	1,798,920	1,095,552
Losses/ (Gains) on financial liabilities at fair value through profit or loss		35,732	(1,025,012)	703,368
Ending balance		$ 809,640	$ 773,908	$ 1,798,920

Segment Information - Additiona

Segment Information - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Segment	Dec. 31, 2017TWD ($)Segment	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of major customers [line items]
Operating segment | Segment	2	2
Reportable segment | Segment	1	1
Operating Revenues	$ 2,818,974	$ 83,554,385	$ 85,111,913	$ 82,839,922
Customer A [member]
Disclosure of major customers [line items]
Operating Revenues | $		17,091,540	15,979,382	15,096,281
Customer B [member]
Disclosure of major customers [line items]
Operating Revenues | $		$ 8,405,084	$ 11,794,072	$ 10,053,063

Segment Information - Summary o

Segment Information - Summary of Breakdown of Revenue From Different Products and Services (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of products and services [line items]
Revenue	$ 2,818,974	$ 83,554,385	$ 85,111,913	$ 82,839,922
Packaging [member]
Disclosure of products and services [line items]
Revenue		70,851,943	74,315,486	72,752,428
Testing [member]
Disclosure of products and services [line items]
Revenue		11,983,667	10,227,996	9,551,025
Other [member]
Disclosure of products and services [line items]
Revenue		$ 718,775	$ 568,431	$ 536,469

Segment Information - Summar157

Segment Information - Summary of Operations in Different Geographic Areas (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2017TWD ($)	Dec. 31, 2016TWD ($)	Dec. 31, 2015TWD ($)
Disclosure of products and services [line items]
Revenues	$ 2,818,974	$ 83,554,385	$ 85,111,913	$ 82,839,922
Noncurrent Assets		66,377,876	68,405,168	67,799,740
United States [member]
Disclosure of products and services [line items]
Revenues		32,018,540	33,624,139	30,076,050
Noncurrent Assets		1,739	1,728	1,553
China [member]
Disclosure of products and services [line items]
Revenues		24,778,540	22,724,680	21,318,660
Noncurrent Assets		11,803,140	9,014,191	8,068,694
Taiwan [member]
Disclosure of products and services [line items]
Revenues		15,494,157	19,683,484	18,106,693
Noncurrent Assets		54,572,997	59,371,230	59,606,745
Europe [member]
Disclosure of products and services [line items]
Revenues		8,315,142	6,794,827	8,470,707
Other Countries [member]
Disclosure of products and services [line items]
Revenues		2,948,006	2,284,783	4,867,812
Noncurrent Assets		$ 0	$ 18,019	$ 122,748

Valuation and Qualifying Acc158

Valuation and Qualifying Account - Valuation and Qualifying Account (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts [member]
Valuation and qualifying accounts disclosure [line items]
Balance at beginning of period	$ 1,695	$ 1,695	$ 1,695
Additions Charged to Expense	11,911	0	0
Deductions Write-offs	1,673	0	0
Exchange difference on translation of foreign financial statement	0	0	0
Balance at end of period	11,933	1,695	1,695
Allowance for sale discounts [member]
Valuation and qualifying accounts disclosure [line items]
Balance at beginning of period	3,006	14,056	275,705
Additions Charged to Expense	0	0	152,224
Deductions Write-offs	3,006	11,050	413,668
Exchange difference on translation of foreign financial statement	0	0	(205)
Balance at end of period	0	3,006	14,056
Allowance for loss on obsolescence and decline in market value of inventory [member]
Valuation and qualifying accounts disclosure [line items]
Balance at beginning of period	271,452	163,056	143,348
Additions Charged to Expense	69,869	112,374	20,480
Deductions Write-offs	0	0	0
Exchange difference on translation of foreign financial statement	(935)	(3,978)	(772)
Balance at end of period	340,386	271,452	163,056
Allowance for loss on idle assets [member]
Valuation and qualifying accounts disclosure [line items]
Balance at beginning of period	125,359	112,557	93,361
Additions Charged to Expense	88,231	91,247	64,996
Deductions Write-offs	97,961	76,822	45,220
Exchange difference on translation of foreign financial statement	(489)	(1,623)	(580)
Balance at end of period	$ 115,140	$ 125,359	$ 112,557