Magnachip Semiconductor (MX) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	MX
Entity Registrant Name	MAGNACHIP SEMICONDUCTOR Corp
Entity Central Index Key	1,325,702
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		34,621,962

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 133,482	$ 128,575
Accounts receivable, net	103,221	92,026
Unbilled accounts receivable	35,837
Inventories, net	71,532	73,073
Other receivables	7,510	4,292
Prepaid expenses	15,481	9,250
Hedge collateral (Note 7)	6,970	7,600
Other current assets (Notes 7 and 18)	10,711	15,444
Total current assets	384,744	330,260
Property, plant and equipment, net	200,393	205,903
Intangible assets, net	3,995	4,061
Long-term prepaid expenses	17,744	12,791
Other non-current assets	5,830	5,774
Total assets	612,706	558,789
Current liabilities
Accounts payable	81,570	65,940
Other accounts payable	16,445	10,261
Accrued expenses	45,641	51,746
Deferred revenue	11,682	8,335
Other current liabilities (Note 7)	4,772	1,860
Total current liabilities	160,110	138,142
Long-term borrowings, net	305,039	303,416
Accrued severance benefits, net	148,148	148,905
Other non-current liabilities (Note 4)	16,861	7,963
Total liabilities	630,158	598,426
Commitments and contingencies (Note 18)
Stockholders' equity
Common stock, $0.01 par value, 150,000,000 shares authorized, 42,994,105 shares issued and 34,600,464 outstanding at September 30, 2018 and 42,563,808 shares issued and 34,189,599 outstanding at December 31, 2017	430	426
Additional paid-in capital	141,261	136,259
Accumulated deficit	(33,925)	(40,889)
Treasury stock, 8,393,641 shares at September 30, 2018 and 8,374,209 shares at December 31, 2017	(102,518)	(102,319)
Accumulated other comprehensive loss	(22,700)	(33,114)
Total stockholders' deficit	(17,452)	(39,637)
Total liabilities and stockholders' equity	$ 612,706	$ 558,789

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	42,994,105	42,563,808
Common stock, shares outstanding	34,600,464	34,189,599
Treasury stock, shares	8,393,641	8,374,209

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 206,000	$ 176,697	$ 571,504	$ 505,092
Cost of sales	150,251	126,387	417,320	366,550
Gross profit	55,749	50,310	154,184	138,542
Operating expenses
Selling, general and administrative expenses	18,566	17,266	55,123	58,144
Research and development expenses	18,918	17,554	59,503	52,440
Restructuring and other gain				(17,010)
Early termination charges				13,369
Total operating expenses	37,484	34,820	114,626	106,943
Operating income	18,265	15,490	39,558	31,599
Interest expense	(5,587)	(5,485)	(16,539)	(16,099)
Foreign currency gain (loss), net	6,002	(3,662)	(20,129)	26,219
Other income (expense), net	150	198	(291)	1,892
Income before income taxes	18,830	6,541	2,599	43,611
Income tax expenses	1,608	937	4,119	2,328
Net income (loss)	$ 17,222	$ 5,604	$ (1,520)	$ 41,283
Earnings (loss) per common share-
Basic	$ 0.50	$ 0.16	$ (0.04)	$ 1.22
Diluted	$ 0.41	$ 0.15	$ (0.04)	$ 1.02
Weighted average number of shares-
Basic	34,573,377	34,103,029	34,416,887	33,907,581
Diluted	46,021,610	45,542,418	34,416,887	44,438,871

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 17,222	$ 5,604	$ (1,520)	$ 41,283
Other comprehensive income (loss)
Foreign currency translation adjustments	(3,827)	2,692	15,806	(23,270)
Derivative adjustments
Fair valuation of derivatives	1,046	(193)	(891)	716
Reclassification adjustment for loss (gain) on derivatives included in net income (loss)	140	(42)	(4,501)	(1,347)
Net current-period other comprehensive income (loss)	(2,641)	2,457	10,414	(23,901)
Total comprehensive income	$ 14,581	$ 8,061	$ 8,894	$ 17,382

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Outstanding [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Balance, beginning at Dec. 31, 2016	$ (72,114)		$ 416	$ 130,189	$ (125,825)	$ (90,918)	$ 14,024
Balance, Shares beginning at Dec. 31, 2016		35,048,338
Stock-based compensation	1,614			1,614
Exercise of stock options	3,391		5	3,386
Exercise of stock options, Shares		487,873
Settlement of restricted stock units			4	(4)
Settlement of restricted stock units, Shares		397,522
Acquisition of treasury stock	$ (11,401)					(11,401)
Acquisition of treasury stock, Shares	(1,795,444)	(1,795,444)
Other comprehensive income, net	$ (23,901)						(23,901)
Net income (loss)	41,283				41,283
Balance, ending at Sep. 30, 2017	(61,128)		425	135,185	(84,542)	(102,319)	(9,877)
Balance, Shares ending at Sep. 30, 2017		34,138,289
Balance, beginning at Jun. 30, 2017							(12,334)
Other comprehensive income, net	2,457						2,457
Net income (loss)	5,604
Balance, ending at Sep. 30, 2017	(61,128)		425	135,185	(84,542)	(102,319)	(9,877)
Balance, Shares ending at Sep. 30, 2017		34,138,289
Balance, beginning at Dec. 31, 2017	(39,637)		426	136,259	(40,889)	(102,319)	(33,114)
Impact of adopting the new revenue standard at Dec. 31, 2017	8,484				8,484
Balance as adjusted, beginning at Dec. 31, 2017	$ (31,153)		426	136,259	(32,405)	(102,319)	(33,114)
Balance, Shares beginning at Dec. 31, 2017	34,189,599	34,189,599
Stock-based compensation	$ 3,893			3,893
Exercise of stock options	1,113		2	1,111
Exercise of stock options, Shares		159,841
Settlement of restricted stock units			2	(2)
Settlement of restricted stock units, Shares		270,456
Acquisition of treasury stock	(199)					(199)
Acquisition of treasury stock, Shares		(19,432)
Other comprehensive income, net	10,414						10,414
Net income (loss)	(1,520)				(1,520)
Balance, ending at Sep. 30, 2018	$ (17,452)		430	141,261	(33,925)	(102,518)	(22,700)
Balance, Shares ending at Sep. 30, 2018	34,600,464	34,600,464
Balance, beginning at Jun. 30, 2018							(20,059)
Other comprehensive income, net	$ (2,641)						(2,641)
Net income (loss)	17,222
Balance, ending at Sep. 30, 2018	$ (17,452)		$ 430	$ 141,261	$ (33,925)	$ (102,518)	$ (22,700)
Balance, Shares ending at Sep. 30, 2018	34,600,464	34,600,464

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net income (loss)	$ (1,520)	$ 41,283
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities
Depreciation and amortization	23,883	20,689
Provision for severance benefits	14,686	15,354
Amortization of debt issuance costs and original issue discount	1,623	1,464
Loss (gain) on foreign currency, net	26,931	(30,615)
Restructuring and other gain		(17,010)
Stock-based compensation	3,893	1,614
Other	(964)	459
Changes in operating assets and liabilities
Accounts receivable, net	(14,282)	(20,241)
Unbilled accounts receivable	1,187
Inventories, net	(30,296)	3,281
Other receivables	(2,669)	3,541
Other current assets	2,514	2,897
Accounts payable	17,414	178
Other accounts payable	(8,811)	(8,378)
Accrued expenses	(5,370)	(16,459)
Deferred revenue	3,560	(2,243)
Other current liabilities	1,533	(822)
Other non-current liabilities	1,035	283
Payment of severance benefits	(9,004)	(19,578)
Other	(329)	(11)
Net cash provided by (used in) operating activities	25,014	(24,314)
Cash flows from investing activities
Proceeds from settlement of hedge collateral	11,290	8,556
Payment of hedge collateral	(10,965)	(14,839)
Proceeds from disposal of plant, property and equipment	1,685	1,128
Purchase of plant, property and equipment	(18,875)	(19,269)
Payment for property related to water treatment facility arrangement	(4,283)
Payment for intellectual property registration	(776)	(977)
Collection of guarantee deposits	794	1,426
Payment of guarantee deposits	(89)	(41)
Other	(38)	24
Net cash used in investing activities	(21,257)	(23,992)
Cash flows from financing activities
Proceeds from issuance of senior notes		86,250
Payment of debt issuance costs		(5,902)
Proceeds from exercise of stock options	1,113	3,391
Acquisition of treasury stock	(199)	(11,401)
Proceeds from property related to water treatment facility arrangement	4,283
Repayment of financing related to water treatment facility arrangement	(73)
Net cash provided by financing activities	5,124	72,338
Effect of exchange rates on cash, cash equivalents and restricted cash	(3,974)	2,787
Net increase in cash, cash equivalents and restricted cash	4,907	26,819
Cash, cash equivalents and restricted cash
Beginning of the period	128,575	101,606
End of the period	133,482	128,425
Supplemental cash flow information
Cash paid for interest	19,219	17,590
Cash paid for income taxes	812	830
Non-cash investing and financing activities
Property, plant and equipment additions in other accounts payable	$ 4,668	$ 2,092

Business, Basis of Presentation

Business, Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Business, Basis of Presentation and Significant Accounting Policies	1. Business, Basis of Presentation and Significant Accounting Policies Business MagnaChip Semiconductor Corporation (together with its subsidiaries, the “Company”) is a designer and manufacturer of analog and mixed-signal semiconductor platform solutions for communications, Internet of Things (“IoT”) applications, consumer, industrial and automotive applications. The Company provides technology platforms for analog, mixed signal, power, high voltage, non-volatile Basis of Presentation The accompanying unaudited interim consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America (“US GAAP”). These interim consolidated financial statements include normal recurring adjustments and the elimination of all intercompany accounts and transactions which are, in the opinion of management, necessary to provide a fair statement of the Company’s financial condition and results of operations for the periods presented. These interim consolidated financial statements are presented in accordance with Accounting Standards Codification 270, “Interim Reporting” The December 31, 2017 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by US GAAP. Upon the adoption of Accounting Standards Update No. 2014-09, 2014-09”) Revenue Recognition The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. Revenue is measured based on a consideration specified in a contract with a customer in exchange for such product or service. The Foundry Services Group of the Company manufactures products based on customers’ specific product designs. The Company recognizes revenue over time for those foundry products without alternative use where the Company has an enforceable right to payment for the related foundry services completed to date. The revenue recognized over time is in proportion of wafer manufacturing costs incurred relative to total estimated costs at completion to measure the Company’s performance to date. However, in certain circumstances, the Company may not have an enforceable right to payment for performed foundry services pursuant to a customer contract or an individual purchase order. In this situation, the Company recognizes revenue when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement. The Standards Products Group of the Company sells products manufactured based on the Company’s design. The Standard Products Group’s products are either standardized with an alternative use or the Company does not have an enforceable right to payment for the related manufacturing services completed to date. For those products, revenue is recognized when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement. A portion of the Company’s sales are made through distributors for which the Company applies the same revenue recognition guidance as described above. The Company defers recognition of revenue when it receives cash from certain customers and distributors for the sale of products prior to obtaining an enforceable right to payment for performance completed to date or control of the product being transferred to the customer. In accordance with revenue recognition guidance, any tax assessed by a governmental authority that is both imposed on and concurrent with a specific revenue-producing transaction, and that is collected by the Company from a customer, is excluded from revenue and presented in the statement of operations on a net basis. The Company provides a warranty, under which customers can return defective products. The Company estimates the costs related to those defective product returns and records them as a component of cost of sales. In addition, the Company offers sales returns (other than those that relate to defective products under warranty), cash discounts for early payments, volume rebates and certain allowances to its customers, including distributors. The Company records reserves for those returns, discounts and allowances as a deduction from sales, based on historical experience and other quantitative and qualitative factors. Substantially all of the Company’s contracts are one year or less in duration. The standard payment terms with customers is generally thirty to sixty days from the time of shipment, product delivery at the customer’s location or customer acceptance, depending on the terms of the related arrangement. Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2018-13 “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement” (“ASU 2018-13”). ASU 2018-13 amends existing fair value measurement disclosure requirements by adding, changing, or removing certain disclosures. ASU 2018-13 In February 2018, the FASB issued Accounting Standards Update No. 2018-02 2018-02”). 2018-02 2018-02 In August 2017, the FASB issued Accounting Standards Update No. 2017-12, 2017-12”). 2017-12 2017-12 2017-12 In July 2017, the FASB issued Accounting Standards Update No. 2017-11, (“ASU 2017-11”), 2017-11 2017-11 In February 2016, the FASB issued Accounting Standards Update No. 2016-02, 2016-02”) 2016-02 right-of-use 2016-02 2018-01, 2018-01”). 2018-01 2016-02 2018-10, 2018-10”). 2018-10 2018-11, 2018-11”). 2018-11 2016-02. 2016-02, 2018-01, 2018-11 The Company has not yet completed its assessment. As the Company continues its assessment, it is in the process of identifying and preparing to implement appropriate changes to accounting policies, business processes and internal controls to support the new lease standard and related disclosure requirements. As permitted under ASU 2018-11, Recently Adopted Accounting Pronouncements In May 2017, the FASB issued Accounting Standards Update No. 2017-09, 2017-09”). 2017-09 ASU 2017-09 2017-09 In November 2016, the FASB issued ASU 2016-18, 2016-18”). 2016-18 2016-18 6-inch 2016-18, In August 2016, the FASB issued Accounting Standards Update No. 2016-15, 2016-15”). 2016-15 2016-15 2016-15 In May 2014, the FASB issued ASU 2014-09. 2014-09 2014-09 2016-08, 2016-10, ASU 2016-12, 2016-20, 2016-08, 2016-10, 2016-12 2016-20 2014-09 Prior to the adoption of the new revenue standard effective on January 1, 2018, the Company had historically recognized revenue when risk and reward of ownership pass to the customer either upon shipment, upon product delivery at the customer’s location or upon customer acceptance, depending on the terms of the related arrangement. After the adoption of the new revenue standard effective on January 1, 2018, the Company recognizes revenue over time for those foundry products without alternative use where the Company has an enforceable right to payment for the related foundry services completed to date. As the Company adopted the new revenue standard using the modified retrospective method, it recognized the cumulative effect of initially applying the new revenue standard as an adjustment to the Company’s equity as of January 1, 2018, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for such periods. The cumulative-effect adjustments increased unbilled accounts receivable by $38,307 thousand and decreased inventories, net by $29,823 thousand, resulting in a net increase of $8,484 thousand in the Company’s beginning equity as of January 1, 2018. There was no net income tax impact from those cumulative-effect adjustments due to full allowance on deferred tax assets. Of the recorded unbilled accounts receivable of $38,307 thousand as of January 1, 2018, $871 thousand and $35,909 thousand were billed to customers upon shipment, upon product delivery or upon customer acceptance, depending on the terms of the related arrangement, during the three and nine months ended September 30, 2018, respectively. Of the recorded deferred revenue of $8,335 thousand as of December 31, 2017, $2,256 thousand and $3,478 thousand were recognized as revenue during the three and nine months ended September 30, 2018, respectively. The impacts of adopting the new revenue standard on the Company’s consolidated financial statements for the nine months ended September 30, 2018 are as follows (in thousands): As of September 30, 2018 As Reported Adjustments Amounts Without Adoption of Topic 606 (In thousands of US dollars, except share data) Assets Current assets Unbilled accounts receivable $ 35,837 $ 35,837 $ — Inventories, net 71,532 (27,675 ) 99,207 Total current assets 384,744 8,162 376,582 Total assets 612,706 8,162 604,544 Liabilities and Stockholders’ Equity Stockholders’ equity Accumulated deficit (33,925 ) 8,505 (42,430 ) Accumulated other comprehensive loss (22,700 ) (343 ) (22,357 ) Total stockholders’ deficit (17,452 ) 8,162 (25,614 ) Total liabilities and stockholders’ deficit $ 612,706 $ 8,162 $ 604,544 Unbilled accounts receivable represents the Company’s contractual right to consideration for manufacturing work performed on a customer contract or an individual purchase order basis, which has not been invoiced to the customer. Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 As Reported As Adjusted Amounts Without Adoption of Topic 606 As Reported As Adjusted Amounts Without Adoption of Topic 606 (In thousands of US dollars, except share data) Net sales $ 206,000 $ (299 ) $ 206,299 $ 571,504 $ (1,186 ) $ 572,690 Cost of sales 150,251 803 149,448 417,320 (1,207 ) 418,527 Gross profit 55,749 (1,102 ) 56,851 154,184 21 154,163 Operating income 18,265 (1,102 ) 19,367 39,558 21 39,537 Income before income tax expenses 18,830 (1,102 ) 19,932 2,599 21 2,578 Net income (loss) $ 17,222 $ (1,102 ) $ 18,324 $ (1,520 ) $ 21 $ (1,541 ) Earnings (loss) per common share— Basic $ 0.50 $ (0.03 ) $ 0.53 $ (0.04 ) $ — $ (0.04 ) Diluted $ 0.41 $ (0.02 ) $ 0.43 $ (0.04 ) $ — $ (0.04 )

Sales of Accounts Receivable an

Sales of Accounts Receivable and Receivable Discount Program	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Sales of Accounts Receivable and Receivable Discount Program	2. Sales of Accounts Receivable and Receivable Discount Program The Company has entered into an agreement to sell selected trade accounts receivable to a financial institution from time to time since March 2012. After the sale, the Company does not retain any interest in the receivables and the applicable financial institution collects these accounts receivable directly from the customer. The proceeds from the sales of these accounts receivable totaled $17,156 thousand and $16,180 thousand for the nine months ended September 30, 2018 and 2017, respectively, and these sales resulted in pre-tax The Company uses receivable discount programs with certain customers. These discount arrangements allow the Company to accelerate collection of customers’ receivables.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Inventories	3. Inventories Inventories as of September 30, 2018 and December 31, 2017 consist of the following (in thousands): September 30, 2018 December 31, 2017 Finished goods $ 11,799 $ 13,737 Semi-finished goods and work-in-process 42,322 53,148 Raw materials 17,469 12,445 Materials in-transit 3,792 134 Less: inventory reserve (3,850 ) (6,391 ) Inventories, net $ 71,532 $ 73,073 Changes in inventory reserve for the three and nine months ended September 30, 2018 and 2017 are as follows (in thousands): Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 Beginning balance $ (4,699 ) $ (6,391 ) $ (5,297 ) $ (7,177 ) Change in reserve Inventory reserve charged to costs of sales (980 ) (2,837 ) (2,084 ) (3,479 ) Sale of previously reserved inventory 1,208 1,681 816 3,380 228 (1,156 ) (1,268 ) (99 ) Write off 656 3,497 433 1,584 Translation adjustments (35 ) 200 43 (397 ) Ending balance $ (3,850 ) $ (3,850 ) $ (6,089 ) $ (6,089 ) Inventory reserve represents the Company’s best estimate in value lost due to excessive inventory level, physical deterioration, obsolescence, changes in price levels, or other causes based on individual facts and circumstances. Inventory reserve relates to inventory items including finished goods, semi-finished goods, work-in-process

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	4. Property, Plant and Equipment Property, plant and equipment as of September 30, 2018 and December 31, 2017 are comprised of the following (in thousands): September 30, 2018 December 31, 2017 Buildings and related structures $ 70,840 $ 69,958 Machinery and equipment 313,611 308,713 Others 45,571 42,497 430,022 421,168 Less: accumulated depreciation (245,122 ) (231,356 ) Land 15,493 16,091 Property, plant and equipment, net $ 200,393 $ 205,903 Aggregate depreciation expenses totaled $23,272 thousand and $20,224 thousand for the nine months ended September 30, 2018 and 2017, respectively. As of June 29, 2018, the Company’s Korean subsidiary entered into an arrangement whereby it acquired a water treatment facility to support its fab in Gumi, Korea from SK Hynix for $4,172 thousand, and sold it for $4,172 thousand to a third party management company that the Company has engaged to run the facility for a 10-year non-current

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	5. Intangible Assets Intangible assets as of September 30, 2018 and December 31, 2017 are comprised of the following (in thousands): September 30, 2018 Gross amount Accumulated amortization Net amount Technology $ 19,444 $ (19,444 ) $ — Customer relationships 27,926 (27,926 ) — Intellectual property assets 11,448 (7,453 ) 3,995 Intangible assets, net $ 58,818 $ (54,823 ) $ 3,995 December 31, 2017 Gross amount Accumulated amortization Net amount Technology $ 20,194 $ (20,194 ) $ — Customer relationships 29,002 (29,002 ) — Intellectual property assets 11,319 (7,258 ) 4,061 Intangible assets, net $ 60,515 $ (56,454 ) $ 4,061 Aggregate amortization expenses for intangible assets totaled $611 thousand and $465 thousand for the nine months ended September 30, 2018 and 2017, respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses as of September 30, 2018 and December 31, 2017 are comprised of the following (in thousands): September 30, 2018 December 31, 2017 Payroll, benefits and related taxes, excluding severance benefits $ 19,237 $ 16,724 Withholding tax attributable to intercompany interest income 20,062 18,138 Interest on senior notes 3,463 8,268 Outside service fees 1,272 1,942 Others 1,607 6,674 Accrued expenses $ 45,641 $ 51,746

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	7. Derivative Financial Instruments The Company’s Korean subsidiary from time to time has entered into zero cost collar and forward contracts to hedge the risk of changes in the functional-currency-equivalent cash flows attributable to currency rate changes on U.S. dollar denominated revenues. Details of derivative contracts as of September 30, 2018 are as follows (in thousands): Date of transaction Type of derivative Total notional amount Month of settlement June 18, 2018 Zero cost collar $ 15,000 October 2018 to December 2018 June 18, 2018 Forward $ 30,000 October 2018 to December 2018 June 27, 2018 Zero cost collar $ 27,000 October 2018 to June 2019 June 27, 2018 Forward $ 48,000 October 2018 to June 2019 Details of derivative contracts as of December 31, 2017 are as follows (in thousands): Date of transaction Type of derivative Total notional amount Month of settlement June 22, 2017 Zero cost collar $ 20,000 January 2018 to February 2018 September 28, 2017 Zero cost collar $ 54,000 January 2018 to June 2018 September 28, 2017 Forward $ 36,000 January 2018 to June 2018 The zero cost collar and forward contracts qualify as cash flow hedges under ASC 815, “Derivatives and Hedging,” since at both the inception of the contracts and on an ongoing basis, the hedging relationship was and is expected to be highly effective in achieving offsetting cash flows attributable to the hedged risk during the term of the contracts. The Company is utilizing the “hypothetical derivative” method to measure the effectiveness by comparing the changes in value of the actual derivative versus the change in fair value of the “hypothetical derivative.” The fair values of the Company’s outstanding zero cost collar and forward contracts recorded as assets and liabilities as of September 30, 2018 and December 31, 2017 are as follows (in thousands): Derivatives designated as hedging instruments: September 30, 2018 December 31, 2017 Asset Derivatives: Zero cost collars Other current assets $ — $ 2,827 Forward Other current assets $ — $ 2,352 Liability Derivatives: Zero cost collars Other current liabilities $ 257 $ — Forward Other current liabilities $ 1,174 $ — Offsetting of derivative liabilities as of September 30, 2018 is as follows (in thousands): As of September 30, 2018 Gross amounts of recognized liabilities Gross amounts offset in the balance sheets Net amounts of liabilities presented in the balance sheets Gross amounts not offset in the balance sheets Net amount Financial instruments Cash collateral pledged Liability Derivatives: Zero cost collars $ 257 $ — $ 257 $ — $ (340 ) $ (83 ) Forward $ 1,174 $ — $ 1,174 $ — $ (1,330 ) $ (156 ) Offsetting of derivative assets as of December 31, 2017 is as follows (in thousands): As of December 31, 2017 Gross amounts of recognized assets Gross amounts offset in the balance sheets Net amounts of assets presented in the balance sheets Gross amounts not offset in the balance sheets Net amount Financial instruments Cash collateral pledged Asset Derivatives: Zero cost collars $ 2,827 $ — $ 2,827 $ — $ — $ 2,827 Forward $ 2,352 $ — $ 2,352 $ — $ — $ 2,352 For derivative instruments that are designated and qualify as cash flow hedges, the effective portion of the gain or loss on the derivative is reported as a component of accumulated other comprehensive income (“AOCI”) and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative, representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness, are recognized in current earnings. The following table summarizes the impact of derivative instruments on the consolidated statement of operations for the three months ended September 30, 2018 and 2017 (in thousands): Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion) Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion) Location of Gain (Loss) Recognized in Statement of Operations on Derivative (Ineffective Portion) Amount of Gain Statement of Operations on Derivatives (Ineffective Portion) Three Months Ended September 30, Three Months Ended September 30, Three Months Ended September 30, 2018 2017 2018 2017 2018 2017 Zero cost collars $ 386 $ (217 ) Net sales $ — $ — Other income (expenses), net $ 18 $ (142 ) Forwards $ 660 $ 24 Net sales $ (140 ) $ 42 Other income (expenses), net $ (536 ) $ (228 ) Total $ 1,046 $ (193 ) $ (140 ) $ 42 $ (518 ) $ (370 ) The following table summarizes the impact of derivative instruments on the consolidated statement of operations for the nine months ended September 30, 2018 and 2017 (in thousands): Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain Reclassified from AOCI into Statement of Operations (Effective Portion) Amount of Gain Reclassified from AOCI into Statement of Operations (Effective Portion) Location of Gain (Loss) Recognized in Statement of Operations on Derivative (Ineffective Portion) Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion) Nine Months Ended September 30, Nine Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 2018 2017 Zero cost collars $ (756 ) $ 666 Net sales $ 2,191 $ 1,305 Other income (expenses), net $ (300 ) $ 127 Forwards $ (136 ) $ 50 Net sales $ 2,310 $ 42 Other income (expenses), net $ (1,926 ) $ (327 ) Total $ (892 ) $ 716 $ 4,501 $ 1,347 $ (2,226 ) $ (200 ) As of September 30, 2018, the amount expected to be reclassified from accumulated other comprehensive loss into loss within the next twelve months is $94 thousand. The Company set aside $5,300 thousand and $7,600 thousand of cash deposits to the counterparty, Nomura Financial Investment (Korea) Co., Ltd. (“NFIK”) as required for the zero cost collar and forward contracts outstanding as of September 30, 2018 and December 31, 2017, respectively. These cash deposits are recorded as hedge collateral on the consolidated balance sheets. The Company is required to deposit additional cash collateral with NFIK for any exposure in excess of $500 thousand and $1,670 thousand of additional cash collateral were required as of September 30, 2018 and recorded as hedge collateral on the consolidated balance sheets. These outstanding zero cost collar and forward contracts are subject to termination if the sum of qualified and unrestricted cash and cash equivalents held by the Company is less than $30,000 thousand on the last day of a fiscal quarter.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. Fair Value Measurements Fair Value of Financial Instruments As of September 30, 2018, the following table represents the Company’s liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value September 30, 2018 Fair Value Measurement September 30, 2018 Quoted Prices in Active Markets for Identical Asset (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Liabilities: Derivative liabilities (other current liabilities) $ 1,431 $ 1,431 — $ 1,431 — As of December 31, 2017, the following table represents the Company’s assets measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value December 31, 2017 Fair Value Measurement December 31, 2017 Quoted Prices in Active Markets for Identical Asset (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Derivative assets (other current assets) $ 5,179 $ 5,179 — $ 5,179 — Items not reflected in the table above include cash equivalents, accounts receivable, other receivables, accounts payable, and other accounts payable, fair value of which approximate carrying values due to the short-term nature of these instruments. The fair value of assets and liabilities whose carrying value approximates fair value is determined using Level 2 inputs. Fair Value of Long-term Borrowings September 30, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value (In thousands of US dollars) Long-term Borrowings: 5.0% Exchangeable Senior Notes due March 2021 (Level 2) $ 82,593 $ 129,778 $ 81,576 $ 127,617 6.625% Senior Notes due July 2021 (Level 2) $ 222,446 $ 222,244 $ 221,840 $ 224,719 On January 17, 2017, the Company’s wholly-owned subsidiary, MagnaChip Semiconductor S.A., closed an offering (the “Exchangeable Notes Offering”) of 5.0% Exchangeable Senior Notes due March 1, 2021 (the “Exchangeable Notes”) of $86,250 thousand, which represents the principal amount, excluding $5,902 thousand of debt issuance costs. The Company estimates the fair value of the Exchangeable Notes using the market approach, which utilizes quoted market prices that fall under Level 2. For further description of the Exchangeable Notes, see Note 9, “Long-term Borrowings”. On July 18, 2013, the Company issued 6.625% senior notes due July 15, 2021 (the “2021 Notes”) of $225.0 million, which represents the principal amount, excluding $1.1 million of original issue discount and $5.0 million of debt issuance costs. The Company estimates the fair value of the 2021 Notes using the market approach, which utilizes quoted market prices that fall under Level 2. For further description of the 2021 Notes, see Note 9, “Long-term Borrowings”. Fair Values Measured on a Non-recurring The Company’s non-financial non-recurring

Long-Term Borrowings

Long-Term Borrowings	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Long-Term Borrowings	9. Long-Term Borrowings Long-term borrowings as of September 30, 2018 and December 31, 2017 are as follows (in thousands): September 30, 2018 December 31, 2017 5.0% Exchangeable Senior Notes due March 2021 $ 86,250 $ 86,250 6.625% Senior Notes due July 2021 $ 225,000 $ 225,000 Less: unamortized discount and debt issuance costs (6,211 ) (7,834 ) Long-term borrowings, net of unamortized discount and debt issuance costs $ 305,039 $ 303,416 5.0% Exchangeable Senior Notes On January 17, 2017, MagnaChip Semiconductor S.A. closed the Exchangeable Notes Offering of $86,250 thousand aggregate principal amount of 5.0% Exchangeable Notes. Interest on the Exchangeable Notes accrues at a rate of 5.0% per annum, payable semi-annually on March 1 and September 1 of each year, beginning on March 1, 2017. The Exchangeable Notes will mature on March 1, 2021, unless earlier repurchased or converted. Holders may convert their notes at their option at any time prior to the close of business on the business day immediately preceding the stated maturity date. The Company used a portion of the net proceeds from the issuance to repurchase 1,795,444 shares of common stock under its stock repurchase program at an aggregate cost of $11,401 thousand. Upon conversion, the Company will deliver for each $1,000 principal amount of converted notes a number of shares equally to the exchange rate, which will initially be 121.1387 shares of common stock per $1 thousand principal amount of Exchangeable Notes, equivalent to an initial exchange price of approximately $8.26 per share of common stock. The exchange rate will be subject to adjustment in some circumstances, but will not be adjusted for any accrued and unpaid interest. In addition, if a “make-whole fundamental change” (as defined in the Exchangeable Notes indenture (the “Exchangeable Notes Indenture”)) occurs prior to the stated maturity date, the Company will increase the exchange rate for a holder who elects to convert its notes in connection with such make-whole fundamental change in certain circumstances. MagnaChip Semiconductor S.A. may also, under certain circumstances, be required to pay additional amounts to holders of Exchangeable Notes if withholding or deduction is required in a relevant tax jurisdiction. If the Company undergoes a fundamental change, subject to certain conditions, holders may require the Company to repurchase for cash all or part of their notes at a purchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change purchase date. In addition, upon certain events of default described in the Exchangeable Notes Indenture, the trustee or holders of at least 25% principal amount of the Exchangeable Notes may declare 100% of the then outstanding Exchangeable Notes due and payable in full, together with all accrued and unpaid interest thereon. Payment of principal on the Exchangeable Notes may also accelerate and become automatically due and payable upon certain events of default involving bankruptcy or insolvency proceedings involving the Company, MagnaChip Semiconductor S.A. and their significant subsidiaries. The Exchangeable Notes are not redeemable at the option of MagnaChip Semiconductor S.A. prior to the maturity date. The Exchangeable Notes Indenture contains covenants that limit the ability of the Company, MagnaChip Semiconductor S.A. and the Company’s other restricted subsidiaries to: (i) declare or pay any dividend or make any payment or distribution on account of or purchase or redeem the Company’s capital stock or equity interests of the restricted subsidiaries; (ii) make any principal payment on, or redeem or repurchase, prior to any scheduled repayment or maturity, any subordinated indebtedness; (iii) make certain investments; (iv) incur additional indebtedness and issue certain types of capital stock; (v) create or incur any lien (except for permitted liens) that secures obligations under any indebtedness; (vi) merge with or into or sell all or substantially all of the Company’s assets to other companies; (vii) enter into certain types of transactions with affiliates; (viii) guarantee the payment of any indebtedness; and (ix) designate unrestricted subsidiaries. These covenants are subject to a number of exceptions and qualifications. Certain of these restrictive covenants will terminate if the Exchangeable Notes are rated investment grade at any time. The Company incurred debt issuance costs of $5,902 thousand related to the issuance of the Exchangeable Notes. The debt issuance costs are recorded as a direct deduction from the long-term borrowings in the consolidated balance sheets and amortized to interest expense using the effective interest method over the term of the Exchangeable Notes. Interest expense related to the Exchangeable Notes for the three and nine months ended September 30, 2018 were $1,422 thousand and $4,251 thousand, respectively. Interest expense related to the Exchangeable Notes for the three and nine months ended September 30, 2017 were $1,400 thousand and $3,942 thousand, respectively. 6.625% Senior Notes On July 18, 2013, the Company issued a $225,000,000 aggregate principal amount of the 2021 Notes at a price of 99.5%. Interest on the 2021 Notes accrues at a rate of 6.625% per annum, payable semi-annually on January 15 and July 15 of each year, beginning on January 15, 2014. The Company may on any one or more occasions redeem all or a part of the 2021 Notes, at a redemption price equal to 101.656% and 100% of the principal amount of the notes redeemed on or after July 15, 2018 and 2019, respectively, plus accrued and unpaid interest and special interest, if any, on the notes redeemed, to the applicable date of redemption. The Indenture relating to the 2021 Notes contains covenants that limit the ability of the Company and its restricted subsidiaries to: (i) declare or pay any dividend or make any payment or distribution on account of or purchase or redeem the Company’s capital stock or equity interests of the restricted subsidiaries; (ii) make any principal payment on, or redeem or repurchase, prior to any scheduled repayment or maturity, any subordinated indebtedness; (iii) make certain investments; (iv) incur additional indebtedness and issue certain types of capital stock; (v) create or incur any lien (except for permitted liens) that secures obligations under any indebtedness; (vi) merge with or into or sell all or substantially all of the Company’s assets to other companies; (vii) enter into certain types of transactions with affiliates; (viii) guarantee the payment of any indebtedness; (ix) enter into sale-leaseback transactions; (x) enter into agreements that would restrict the ability of the restricted subsidiaries to make distributions with respect to their equity to the Company or other restricted subsidiaries, to make loans to the Company or other restricted subsidiaries or to transfer assets to the Company or other restricted subsidiaries; and (xi) designate unrestricted subsidiaries. These covenants are subject to a number of exceptions and qualifications. Certain of these restrictive covenants will terminate if the 2021 Notes are rated investment grade at any time. The Company incurred original issue discount of $1,125 thousand and debt issuance costs of $5,039 thousand related to the issuance of the 2021 Notes. The original issue discount and the debt issuance costs are recorded as a direct deduction from the long-term borrowings in the consolidated balance sheets and amortized to interest expense using the effective interest method over the term of the 2021 Notes. Interest expenses related to the 2021 Notes for the three and nine months ended September 30, 2018 were $3,933 thousand and $11,785 thousand, respectively. Interest expenses related to the 2021 Notes for the three and nine months ended September 30, 2017 were $3,918 thousand and $11,744 thousand, respectively.

Accrued Severance Benefits

Accrued Severance Benefits	9 Months Ended
	Sep. 30, 2018
Postemployment Benefits [Abstract]
Accrued Severance Benefits	10. Accrued Severance Benefits The majority of accrued severance benefits are for employees in the Company’s Korean subsidiary. Pursuant to the Employee Retirement Benefit Security Act of Korea, eligible employees and executive officers with one or more years of service are entitled to severance benefits upon the termination of their employment based on their length of service and rate of pay. As of September 30, 2018, 98% of employees of the Company were eligible for severance benefits. Changes in accrued severance benefits are as follows (in thousands): Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 Beginning balance $ 146,375 $ 149,795 $ 130,894 $ 130,144 Provisions 5,521 14,686 4,578 15,354 Severance payments (3,250 ) (9,004 ) (1,496 ) (19,578 ) Translation adjustments 1,194 (5,637 ) (852 ) 7,204 149,840 149,840 133,124 133,124 Less: Cumulative contributions to severance insurance deposit accounts (858 ) (858 ) — — The National Pension Fund (236 ) (236 ) (243 ) (243 ) Group severance insurance plan (598 ) (598 ) (593 ) (593 ) Accrued severance benefits, net $ 148,148 $ 148,148 $ 132,288 $ 132,288 The severance benefits funded through the Company’s National Pension Fund and group severance insurance plan will be used exclusively for payment of severance benefits to eligible employees. These amounts have been deducted from the accrued severance benefit balance. Beginning in July 2018, the Company contributes a certain percentage of severance benefits, accrued for eligible employees for their services from January 1, 2018, to certain severance insurance deposit accounts. These accounts consist of time deposits and other guaranteed principal and interest, and are maintained at insurance companies, banks or security companies for the benefit of employees. The Company deducts the contributions made to certain severance insurance deposit accounts from its accrued severance benefits. The Company is liable to pay the following future benefits to its non-executive Severance benefit Remainder of 2018 $ — 2019 598 2020 1,092 2021 1,569 2022 1,343 2023 1,836 2024 – 2028 27,152 The above amounts were determined based on the non-executive non-executive Korea’s mandatory retirement age is 60 under the Employment Promotion for the Aged Act.

Foreign Currency Gain (Loss), N

Foreign Currency Gain (Loss), Net	9 Months Ended
	Sep. 30, 2018
Foreign Currency [Abstract]
Foreign Currency Gain (Loss), Net	11. Foreign Currency Gain (Loss), Net Net foreign currency gain or loss includes non-cash non-cash

Restructuring and other gain

Restructuring and other gain	9 Months Ended
	Sep. 30, 2018
Restructuring and Related Activities [Abstract]
Restructuring and other gain	12. Restructuring and other gain As of December 21, 2016, the Company entered into a purchase and sale agreement to sell a building located in Cheongju, South Korea. The building has historically been used to house the Company’s six-inch “6-inch In March 2017, the Company sold its sensor product business, which was included in and reported as part of Display Solutions line of its Standard Products Group, to a third party for proceeds of $1,295 thousand, in an effort to improve our overall profitability. The Company recorded $375 thousand net gain from this sale after deducting the book values of certain assets transferred to the buyer.

Early Termination Charges

Early Termination Charges	9 Months Ended
	Sep. 30, 2018
Restructuring and Related Activities [Abstract]
Early Termination Charges	13. Early Termination Charges As of February 22, 2017, the Company’s Board of Directors approved the implementation of a new headcount reduction plan (the “Headcount Reduction Plan”). As of June 30, 2017, 352 employees elected to resign from the Company during the period in which the Headcount Reduction Plan was offered. The total cash cost of approximately $31 million has been fully paid. The Company recorded in its consolidated statement of operations $11,107 thousand and $2,262 thousand in termination related charges as early termination charges for the three months ended March 31, 2017 and June 30, 2017, respectively. The remaining total estimated cost relates to statutory severance benefits, which are required by law and have already been fully accrued in the Company’s financial statements.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	14 . Income Taxes The Company files income tax returns in the U.S., Korea, Japan, Taiwan and various other jurisdictions. The Company is subject to income- or non-income-based Income tax expenses recorded for three and nine months ended September 30, 2018 were $1,608 thousand and was $4,119, respectively. Income tax expenses recorded for three and nine months ended September 30, 2017 were $937 thousand and was $2,328, respectively. The amounts recorded during 2018 included income tax expense for the Korean subsidiary, which is estimated to generate taxable income for the fiscal year ending December 31, 2018, combined with its ability to utilize net operating loss carryforwards up to 70% of taxable income for the year. On December 22, 2017, H.R. 1, originally known as the Tax Cuts and Jobs Act, was enacted in the U.S (the “Tax Reform Act”). The Tax Reform Act reduces the U.S. federal statutory rate to 21.0% from 35.0% effective January 1, 2018. The key provisions contained in the Tax Reform Act are mandatory deemed repatriation tax, global intangible low tax income and foreign derived intangible income provisions. The Company does not expect that the global intangible low tax income and foreign derived intangible income provisions will have any material impact to its income tax expense. The Company is currently reviewing the provision relating to the mandatory deemed repatriation tax and will complete its assessment before the measurement period ending in December 2018.

Geographic and Segment Informat

Geographic and Segment Information	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Geographic and Segment Information	15. Geographic and Segment Information The Company has two operating segments: Foundry Services Group and Standard Products Group. The Company’s chief operating decision maker is its Chief Executive Officer who allocates resources and assesses performance of the business and other activities based on gross profit. In January 2018, as part of the Company’s ongoing portfolio optimization effort to realign business processes and streamline the Company’s organizational structure, the Company transferred a portion of its non-OLED non-OLED The following sets forth information relating to the operating segment (in thousands): Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 As Adjusted September 30, 2018 September 30, 2017 As Adjusted Net Sales Foundry Services Group $ 83,862 $ 89,004 $ 242,198 $ 260,095 Standard Products Group Display Solutions 77,578 48,636 205,986 135,233 Power Solutions 44,458 39,001 123,153 109,595 Total Standard Products Group 122,036 87,637 329,139 244,828 All other 102 56 167 169 Total net sales $ 206,000 $ 176,697 $ 571,504 $ 505,092 Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 As Adjusted September 30, 2018 September 30, 2017 As Adjusted Gross Profit Foundry Services Group $ 20,443 $ 26,344 $ 63,292 $ 74,326 Standard Products Group 35,204 23,910 90,874 64,047 All other 102 56 18 169 Total gross profit $ 55,749 $ 50,310 $ 154,184 $ 138,542 Upon the adoption of the new revenue standard, the Company’s revenue for Foundry Services Group is disaggregated depending on the timing of revenue recognition (in thousands): Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Revenue recognized at the time of shipment or delivery Revenue recognized over time Total Revenue recognized at the time of shipment or delivery Revenue recognized over time Total Net Sales Foundry Services Group $ 26,257 $ 57,605 $ 83,862 $ 52,024 $ 190,174 $ 242,198 The following is a summary of net sales by geographic region, based on the location to which the products are billed (in thousands): Three Months Ended September 30, 2018 September 30, 2017 Korea $ 91,570 $ 74,327 Asia Pacific (other than Korea) 93,475 83,221 U.S.A. 5,831 8,399 Europe 14,444 10,492 Others 680 258 Total $ 206,000 $ 176,697 Nine Months Ended September 30, 2018 September 30, 2017 Korea $ 204,319 $ 207,389 Asia Pacific (other than Korea) 302,906 239,209 U.S.A. 29,242 28,721 Europe 33,041 29,070 Others 1,996 703 Total $ 571,504 $ 505,092 For the three months ended September 30, 2018 and 2017, of the Company’s net sales in Asia Pacific (other than Korea), net sales in Greater China (China, Hong Kong and Macau) represented 64.1% and 47.9%, respectively, and net sales in Taiwan represented 29.7% and 40.7%, respectively. For the nine months ended September 30, 2018 and 2017, of the Company’s net sales in Asia Pacific (other than Korea), net sales in Greater China (China, Hong Kong and Macau) represented 67.6% and 49.5%, respectively, and net sales in Taiwan represented 25.8% and 35.1%, respectively. Net sales from the Company’s top ten largest customers accounted for 65% and 58% for the three months ended September 30, 2018 and 2017, respectively, and 62% and 59% for the nine months ended September 30, 2018 and 2017, respectively. For the three months ended September 30, 2018, the Company had two customers that represented 18.8% and 17.6% of its net sales, respectively, and for the nine months ended September 30, 2018, the Company had two customers that represented 21.6% and 13.0% of its net sales, respectively. For the three months ended September 30, 2017, the Company had one customer that represented 16.9% of its net sales, and for the nine months ended September 30, 2017, the Company had one customer that represented 15.6% of its net sales. 97% of the Company’s property, plant and equipment are located in Korea as of September 30, 2018.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Loss	16. Accumulated Other Comprehensive Loss Accumulated other comprehensive loss consists of the following as of September 30, 2018 and December 31, 2017, respectively (in thousands): September 30, 2018 December 31, 2017 Foreign currency translation adjustments $ (22,607 ) $ (38,413 ) Derivative adjustments (93 ) 5,299 Total $ (22,700 ) $ (33,114 ) Changes in accumulated other comprehensive loss for the three months ended September 30, 2018 and 2017 are as follows (in thousands): Three Months Ended September 30, 2018 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ (18,780 ) $ (1,279 ) $ (20,059 ) Other comprehensive income (loss) before reclassifications (3,827 ) 1,046 (2,781 ) Amounts reclassified from accumulated other comprehensive loss — 140 140 Net current-period other comprehensive income (loss) (3,827 ) 1,186 (2,641 ) Ending balance $ (22,607 ) $ (93 ) $ (22,700 ) Three Months Ended September 30, 2017 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ (11,502 ) $ (832 ) $ (12,334 ) Other comprehensive income (loss) before reclassifications 2,692 (193 ) 2,499 Amounts reclassified from accumulated other comprehensive income — (42 ) (42 ) Net current-period other comprehensive income (loss) 2,692 (235 ) 2,457 Ending balance $ (8,810 ) $ (1,067 ) $ (9,877 ) Changes in accumulated other comprehensive loss for the nine months ended September 30, 2018 and 2017 are as follows (in thousands): Nine Months Ended September 30, 2018 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ (38,413 ) $ 5,299 $ (33,114 ) Other comprehensive income (loss) before reclassifications 15,806 (891 ) 14,915 Amounts reclassified from accumulated other comprehensive income — (4,501 ) (4,501 ) Net current-period other comprehensive income (loss) 15,806 (5,392 ) 10,414 Ending balance $ (22,607 ) $ (93 ) $ (22,700 ) Nine Months Ended September 30, 2017 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ 14,460 $ (436 ) $ 14,024 Other comprehensive income (loss) before reclassifications (23,270 ) 716 (22,554 ) Amounts reclassified from accumulated other comprehensive income — (1,347 ) (1,347 ) Net current-period other comprehensive loss (23,270 ) (631 ) (23,901 ) Ending balance $ (8,810 ) $ (1,067 ) $ (9,877 ) There was no income tax impact related to changes in accumulated other comprehensive loss for the nine months ended September 30, 2018 and 2017 due to net operating loss carry-forwards available to offset taxable income and full allowance for deferred tax assets.

Earnings (Loss) per Share

Earnings (Loss) per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings (Loss) per Share	17. Earnings (Loss) per Share The following table illustrates the computation of basic and diluted earnings (loss) per common share for the three and nine months ended September 30, 2018 and 2017: Three Months Ended September 30, 2018 September 30, 2017 (In thousands of US dollars, except share data) Basic Earnings per Share Net income $ 17,222 $ 5,604 Basic weighted average common stock outstanding 34,573,377 34,103,029 Basic earnings per share $ 0.50 $ 0.16 Diluted Earnings per Share Net income $ 17,222 $ 5,604 Add back: Interest expense on Exchangeable Notes 1,422 1,400 Net income allocated to common stockholders $ 18,644 $ 7,004 Basic weighted average common stock outstanding 34,573,377 34,103,029 Net effect of dilutive equity awards 1,000,020 991,176 Net effect of assumed conversion of 5.0% Exchangeable Notes to common stock 10,448,213 10,448,213 Diluted weighted average common stock outstanding 46,021,610 45,542,418 Diluted earnings per share $ 0.41 $ 0.15 Nine Months Ended September 30, 2018 September 30, 2017 (In thousands of US dollars, except share data) Basic Earnings (Loss) per Share Net income (loss) $ (1,520 ) $ 41,283 Basic weighted average common stock outstanding 34,416,887 33,907,581 Basic earnings (loss) per share $ (0.04 ) $ 1.22 Diluted Earnings (Loss) per Share Net income (loss) $ (1,520 ) $ 41,283 Add back: Interest expense on Exchangeable Notes — 3,942 Net income allocated to common stockholders $ (1,520 ) $ 45,225 Basic weighted average common stock outstanding 34,416,887 33,907,581 Net effect of dilutive equity awards — 695,427 Net effect of assumed conversion of 5.0% Exchangeable Notes to common stock — 9,835,863 Diluted weighted average common stock outstanding 34,416,887 44,438,871 Diluted earnings (loss) per share $ (0.04 ) $ 1.02 The following outstanding instruments were excluded from the computation of diluted earnings (loss) per share, as they have an anti-dilutive effect on the calculation: Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Options 723,117 809,417 2,684,558 860,572 Restricted Stock Units — — 581,759 — For the nine months ended September 30, 2018, 10,448,213 of potential common stock from the assumed conversion of Exchangeable Notes was excluded from the computation of diluted loss per share as the effect was anti-dilutive for the period.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	18. Commitments and Contingencies Long-term Purchase Agreements and Advances to Suppliers The Company purchases raw materials from a variety of vendors. During the normal course of business, in order to manage manufacturing lead times and help assure adequacy supply, the Company from time to time may enter into multi-year purchase agreements, which specify future quantities and pricing of materials to be supplied by the vendors. The Company reviews the terms of the long-term supply agreements and assesses the need for any accrual for estimated losses, such as lower of cost or net realizable value that will not be recovered by future sales prices. No such accrual was required as of September 30, 2018 and December 31, 2017, respectively. The Company, from time to time, may make prepayments to suppliers to procure materials to meet its planned production. The Company recorded prepayments of $8,667 thousand and $7,404 thousand as other current assets as of September 30, 2018 and December 31, 2017, respectively. SEC Enforcement Staff Review In March 2014, the Company voluntarily reported to the Securities and Exchange Commission, or the SEC, that the Company’s Audit Committee had determined that the Company incorrectly recognized revenue on certain transactions and as a result would restate its financial statements, and that the Audit Committee had commenced an independent investigation. Over the course of 2014 and the first two quarters of 2015, the Company voluntarily produced documents to the SEC regarding the various accounting issues identified during the independent investigation, and whether the Company’s hiring of an accountant from the Company’s independent registered public accounting firm impacted that accounting firm’s independence. On July 22, 2014, the Staff of the SEC’s Division of Enforcement obtained a Formal Order of Investigation. On March 12, 2015, the SEC issued a subpoena for documents to the Company in connection with its investigation. On May 1, 2017, the SEC announced that it had reached a final settlement with the Company, resolving the SEC’s investigation. In connection therewith, the Company has consented, without admitting or denying the SEC’s findings, to the entry of an administrative order by the SEC directing that the Company cease and desist from committing or causing any violations of certain provisions of the federal securities laws and related SEC regulations. The SEC’s administrative order was entered on May 1, 2017. The SEC imposed a monetary penalty of $3,000 thousand on the Company. In the first quarter ended March 31, 2017, the Company established a reserve in that amount for the potential settlement of this matter. The reserved monetary penalty of $3,000 thousand was paid to the SEC during the second quarter of 2017. The Company also agreed to an undertaking to cooperate fully with the SEC in any and all investigations, litigations or other proceedings relating to or arising from the matters described in the SEC’s order. In connection with the settlement, the SEC considered remedial acts promptly undertaken by the Company and its cooperation with the SEC staff during the course of the investigation. Among other things, as previously disclosed in the Company’s filings with the SEC, the Audit Committee of the Company self-investigated and self-reported the accounting errors, selected new management and implemented various additional controls designed to prevent similar errors going forward. Securities Class Action Complaints On March 12, 2014, a purported class action was filed against the Company and certain of the Company’s now-former 3:15-cv-01797) now-former 10b-5 On December 10, 2015, the Company and certain of its current and former officers and directors entered into a Memorandum of Understanding with the plaintiffs’ representatives to memorialize an agreement in principle to settle the consolidated securities class action lawsuit, Thomas, et al. v. MagnaChip Semiconductor Corp. et al., Civil Action No. 3:14-CV-01160-JST, out-of-pocket On April 13, 2016, the plaintiffs filed a renewed motion for preliminary approval of the settlement. On July 18, 2016, the court granted plaintiffs’ renewed motion for preliminary approval of the settlement. On October 17, 2016, plaintiffs filed their motions for final approval of the settlement and plan of allocation of the settlement and for an award of attorneys’ fees, reimbursement of litigation expenses, and reimbursement of the costs and expenses of Lead Plaintiff Keith Thomas. On December 1, 2016, following a hearing on November 21, 2016 and an order dated November 21, 2016, the court entered a supplemental order and final judgment (the “Judgment”) granting final approval of the settlement. The Judgment was not appealed within the applicable appeals period (on or before January 3, 2017). The settlement therefore became effective after the expiration of the appeals period. The settlement was fully funded by insurance proceeds. The Company recorded the $23,500 thousand of the settlement obligation for the Class Action Litigation as accrued expenses in the consolidated balance sheets as of December 31, 2015 and as selling, general and administrative expenses in the consolidated statements of operations for the year ended December 31, 2015. The Company recorded $29,571 thousand of the proceeds from the insurers as other receivables in the consolidated balance sheets as of December 31, 2015 and as a deduction of the selling, general and administrative expenses in the consolidated statements of operations for the year ended December 31, 2015. The proceeds from the insurers of $29,571 thousand were deposited into the Company’s escrow account during the first quarter of 2016 and the Company reclassified the $29,571 thousand deposits recorded in other receivables into restricted cash. During the third quarter of 2016, the Company disbursed the aggregate settlement payment of $23,500 thousand after the court granted plaintiffs’ renewed motion for preliminary approval of the settlement in July 2016. Upon the settlement payment, $6,114 thousand of the insurance proceeds remained in the Company’s escrow account. For subsequent treatment of the escrow amount, see “Shareholder Derivative Complaints” below. Shareholder Derivative Complaints A shareholder derivative action, styled Hemmingson et al. v. Elkins et al. No. 1-15-cv-278614, now-former now-former On June 1, 2015, a shareholder derivative action was filed in the Superior Court of the State of California, Santa Clara County styled Bushansky v. Norby, et al. No. 1-15-CV-281284 On January 22, 2016, the Company and the plaintiffs in the Hemmingson Bushansky On February 22, 2016, the plaintiffs filed an unopposed motion for preliminary approval of the proposed derivative settlement. On June 10, 2016, the court granted plaintiffs’ motion for preliminary approval of the proposed settlement. On October 18, 2016, after a hearing held on October 14, 2016, the court entered its order and final judgment (the “Shareholder Derivative Judgment”) granting final approval of the proposed settlement and awarding plaintiffs’ counsel $750 thousand for attorneys’ fees and litigation expenses. The Shareholder Derivative Judgment was not appealed within the applicable appeals period (on or before December 19, 2016). The settlement therefore became effective after the expiration of the appeals period and $2,258 thousand ($2,250 thousand plus applicable interest) was paid to the Company from the escrow account, previously recorded as restricted cash, in December 2016. The remaining restricted cash related to insurance proceeds of $3,078 thousand was also released in December 2016.

Business, Basis of Presentati_2

Business, Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Business	Business MagnaChip Semiconductor Corporation (together with its subsidiaries, the “Company”) is a designer and manufacturer of analog and mixed-signal semiconductor platform solutions for communications, Internet of Things (“IoT”) applications, consumer, industrial and automotive applications. The Company provides technology platforms for analog, mixed signal, power, high voltage, non-volatile
Basis of Presentation	Basis of Presentation The accompanying unaudited interim consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America (“US GAAP”). These interim consolidated financial statements include normal recurring adjustments and the elimination of all intercompany accounts and transactions which are, in the opinion of management, necessary to provide a fair statement of the Company’s financial condition and results of operations for the periods presented. These interim consolidated financial statements are presented in accordance with Accounting Standards Codification 270, “Interim Reporting” The December 31, 2017 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by US GAAP. Upon the adoption of Accounting Standards Update No. 2014-09, 2014-09”)
Revenue Recognition	Revenue Recognition The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. Revenue is measured based on a consideration specified in a contract with a customer in exchange for such product or service. The Foundry Services Group of the Company manufactures products based on customers’ specific product designs. The Company recognizes revenue over time for those foundry products without alternative use where the Company has an enforceable right to payment for the related foundry services completed to date. The revenue recognized over time is in proportion of wafer manufacturing costs incurred relative to total estimated costs at completion to measure the Company’s performance to date. However, in certain circumstances, the Company may not have an enforceable right to payment for performed foundry services pursuant to a customer contract or an individual purchase order. In this situation, the Company recognizes revenue when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement. The Standards Products Group of the Company sells products manufactured based on the Company’s design. The Standard Products Group’s products are either standardized with an alternative use or the Company does not have an enforceable right to payment for the related manufacturing services completed to date. For those products, revenue is recognized when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement. A portion of the Company’s sales are made through distributors for which the Company applies the same revenue recognition guidance as described above. The Company defers recognition of revenue when it receives cash from certain customers and distributors for the sale of products prior to obtaining an enforceable right to payment for performance completed to date or control of the product being transferred to the customer. In accordance with revenue recognition guidance, any tax assessed by a governmental authority that is both imposed on and concurrent with a specific revenue-producing transaction, and that is collected by the Company from a customer, is excluded from revenue and presented in the statement of operations on a net basis. The Company provides a warranty, under which customers can return defective products. The Company estimates the costs related to those defective product returns and records them as a component of cost of sales. In addition, the Company offers sales returns (other than those that relate to defective products under warranty), cash discounts for early payments, volume rebates and certain allowances to its customers, including distributors. The Company records reserves for those returns, discounts and allowances as a deduction from sales, based on historical experience and other quantitative and qualitative factors. Substantially all of the Company’s contracts are one year or less in duration. The standard payment terms with customers is generally thirty to sixty days from the time of shipment, product delivery at the customer’s location or customer acceptance, depending on the terms of the related arrangement.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2018-13 “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement” (“ASU 2018-13”). ASU 2018-13 amends existing fair value measurement disclosure requirements by adding, changing, or removing certain disclosures. ASU 2018-13 In February 2018, the FASB issued Accounting Standards Update No. 2018-02 2018-02”). 2018-02 2018-02 In August 2017, the FASB issued Accounting Standards Update No. 2017-12, 2017-12”). 2017-12 2017-12 2017-12 In July 2017, the FASB issued Accounting Standards Update No. 2017-11, (“ASU 2017-11”), 2017-11 2017-11 In February 2016, the FASB issued Accounting Standards Update No. 2016-02, 2016-02”) 2016-02 right-of-use 2016-02 2018-01, 2018-01”). 2018-01 2016-02 2018-10, 2018-10”). 2018-10 2018-11, 2018-11”). 2018-11 2016-02. 2016-02, 2018-01, 2018-11 The Company has not yet completed its assessment. As the Company continues its assessment, it is in the process of identifying and preparing to implement appropriate changes to accounting policies, business processes and internal controls to support the new lease standard and related disclosure requirements. As permitted under ASU 2018-11,
Recently Adopted Accounting Pronouncements - Compensation-Stock Compensation	In May 2017, the FASB issued Accounting Standards Update No. 2017-09, 2017-09”). 2017-09 ASU 2017-09 2017-09
Recently Adopted Accounting Pronouncements - Restricted Cash	In November 2016, the FASB issued ASU 2016-18, 2016-18”). 2016-18 2016-18 6-inch 2016-18,
Recently Adopted Accounting Pronouncements - Classification of Certain Cash Receipts and Cash Payments	In August 2016, the FASB issued Accounting Standards Update No. 2016-15, 2016-15”). 2016-15 2016-15 2016-15
Recently Adopted Accounting Pronouncements - Revenue from Contracts with Customers	In May 2014, the FASB issued ASU 2014-09. 2014-09 2014-09 2016-08, 2016-10, ASU 2016-12, 2016-20, 2016-08, 2016-10, 2016-12 2016-20 2014-09 Prior to the adoption of the new revenue standard effective on January 1, 2018, the Company had historically recognized revenue when risk and reward of ownership pass to the customer either upon shipment, upon product delivery at the customer’s location or upon customer acceptance, depending on the terms of the related arrangement. After the adoption of the new revenue standard effective on January 1, 2018, the Company recognizes revenue over time for those foundry products without alternative use where the Company has an enforceable right to payment for the related foundry services completed to date. As the Company adopted the new revenue standard using the modified retrospective method, it recognized the cumulative effect of initially applying the new revenue standard as an adjustment to the Company’s equity as of January 1, 2018, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for such periods. The cumulative-effect adjustments increased unbilled accounts receivable by $38,307 thousand and decreased inventories, net by $29,823 thousand, resulting in a net increase of $8,484 thousand in the Company’s beginning equity as of January 1, 2018. There was no net income tax impact from those cumulative-effect adjustments due to full allowance on deferred tax assets. Of the recorded unbilled accounts receivable of $38,307 thousand as of January 1, 2018, $871 thousand and $35,909 thousand were billed to customers upon shipment, upon product delivery or upon customer acceptance, depending on the terms of the related arrangement, during the three and nine months ended September 30, 2018, respectively. Of the recorded deferred revenue of $8,335 thousand as of December 31, 2017, $2,256 thousand and $3,478 thousand were recognized as revenue during the three and nine months ended September 30, 2018, respectively.

Business, Basis of Presentati_3

Business, Basis of Presentation and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Standards Update 2014-09 [Member]
Impacts of Adopting New Revenue Standard on Company's Consolidated Financial Statements	The impacts of adopting the new revenue standard on the Company’s consolidated financial statements for the nine months ended September 30, 2018 are as follows (in thousands): As of September 30, 2018 As Reported Adjustments Amounts Without Adoption of Topic 606 (In thousands of US dollars, except share data) Assets Current assets Unbilled accounts receivable $ 35,837 $ 35,837 $ — Inventories, net 71,532 (27,675 ) 99,207 Total current assets 384,744 8,162 376,582 Total assets 612,706 8,162 604,544 Liabilities and Stockholders’ Equity Stockholders’ equity Accumulated deficit (33,925 ) 8,505 (42,430 ) Accumulated other comprehensive loss (22,700 ) (343 ) (22,357 ) Total stockholders’ deficit (17,452 ) 8,162 (25,614 ) Total liabilities and stockholders’ deficit $ 612,706 $ 8,162 $ 604,544 Unbilled accounts receivable represents the Company’s contractual right to consideration for manufacturing work performed on a customer contract or an individual purchase order basis, which has not been invoiced to the customer. Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 As Reported As Adjusted Amounts Without Adoption of Topic 606 As Reported As Adjusted Amounts Without Adoption of Topic 606 (In thousands of US dollars, except share data) Net sales $ 206,000 $ (299 ) $ 206,299 $ 571,504 $ (1,186 ) $ 572,690 Cost of sales 150,251 803 149,448 417,320 (1,207 ) 418,527 Gross profit 55,749 (1,102 ) 56,851 154,184 21 154,163 Operating income 18,265 (1,102 ) 19,367 39,558 21 39,537 Income before income tax expenses 18,830 (1,102 ) 19,932 2,599 21 2,578 Net income (loss) $ 17,222 $ (1,102 ) $ 18,324 $ (1,520 ) $ 21 $ (1,541 ) Earnings (loss) per common share— Basic $ 0.50 $ (0.03 ) $ 0.53 $ (0.04 ) $ — $ (0.04 ) Diluted $ 0.41 $ (0.02 ) $ 0.43 $ (0.04 ) $ — $ (0.04 )

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories as of September 30, 2018 and December 31, 2017 consist of the following (in thousands): September 30, 2018 December 31, 2017 Finished goods $ 11,799 $ 13,737 Semi-finished goods and work-in-process 42,322 53,148 Raw materials 17,469 12,445 Materials in-transit 3,792 134 Less: inventory reserve (3,850 ) (6,391 ) Inventories, net $ 71,532 $ 73,073
Changes in Inventory Reserve	Changes in inventory reserve for the three and nine months ended September 30, 2018 and 2017 are as follows (in thousands): Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 Beginning balance $ (4,699 ) $ (6,391 ) $ (5,297 ) $ (7,177 ) Change in reserve Inventory reserve charged to costs of sales (980 ) (2,837 ) (2,084 ) (3,479 ) Sale of previously reserved inventory 1,208 1,681 816 3,380 228 (1,156 ) (1,268 ) (99 ) Write off 656 3,497 433 1,584 Translation adjustments (35 ) 200 43 (397 ) Ending balance $ (3,850 ) $ (3,850 ) $ (6,089 ) $ (6,089 )

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment	Property, plant and equipment as of September 30, 2018 and December 31, 2017 are comprised of the following (in thousands): September 30, 2018 December 31, 2017 Buildings and related structures $ 70,840 $ 69,958 Machinery and equipment 313,611 308,713 Others 45,571 42,497 430,022 421,168 Less: accumulated depreciation (245,122 ) (231,356 ) Land 15,493 16,091 Property, plant and equipment, net $ 200,393 $ 205,903

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	Intangible assets as of September 30, 2018 and December 31, 2017 are comprised of the following (in thousands): September 30, 2018 Gross amount Accumulated amortization Net amount Technology $ 19,444 $ (19,444 ) $ — Customer relationships 27,926 (27,926 ) — Intellectual property assets 11,448 (7,453 ) 3,995 Intangible assets, net $ 58,818 $ (54,823 ) $ 3,995 December 31, 2017 Gross amount Accumulated amortization Net amount Technology $ 20,194 $ (20,194 ) $ — Customer relationships 29,002 (29,002 ) — Intellectual property assets 11,319 (7,258 ) 4,061 Intangible assets, net $ 60,515 $ (56,454 ) $ 4,061

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Summary of Accrued Expenses	Accrued expenses as of September 30, 2018 and December 31, 2017 are comprised of the following (in thousands): September 30, 2018 December 31, 2017 Payroll, benefits and related taxes, excluding severance benefits $ 19,237 $ 16,724 Withholding tax attributable to intercompany interest income 20,062 18,138 Interest on senior notes 3,463 8,268 Outside service fees 1,272 1,942 Others 1,607 6,674 Accrued expenses $ 45,641 $ 51,746

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Details of Derivative Contracts	Details of derivative contracts as of September 30, 2018 are as follows (in thousands): Date of transaction Type of derivative Total notional amount Month of settlement June 18, 2018 Zero cost collar $ 15,000 October 2018 to December 2018 June 18, 2018 Forward $ 30,000 October 2018 to December 2018 June 27, 2018 Zero cost collar $ 27,000 October 2018 to June 2019 June 27, 2018 Forward $ 48,000 October 2018 to June 2019 Details of derivative contracts as of December 31, 2017 are as follows (in thousands): Date of transaction Type of derivative Total notional amount Month of settlement June 22, 2017 Zero cost collar $ 20,000 January 2018 to February 2018 September 28, 2017 Zero cost collar $ 54,000 January 2018 to June 2018 September 28, 2017 Forward $ 36,000 January 2018 to June 2018
Fair Values of Outstanding Zero Cost Collar and Forward Contracts Recorded as Assets and Liabilities	The fair values of the Company’s outstanding zero cost collar and forward contracts recorded as assets and liabilities as of September 30, 2018 and December 31, 2017 are as follows (in thousands): Derivatives designated as hedging instruments: September 30, 2018 December 31, 2017 Asset Derivatives: Zero cost collars Other current assets $ — $ 2,827 Forward Other current assets $ — $ 2,352 Liability Derivatives: Zero cost collars Other current liabilities $ 257 $ — Forward Other current liabilities $ 1,174 $ —
Offsetting of Derivative Liabilities	Offsetting of derivative liabilities as of September 30, 2018 is as follows (in thousands): As of September 30, 2018 Gross amounts of recognized liabilities Gross amounts offset in the balance sheets Net amounts of liabilities presented in the balance sheets Gross amounts not offset in the balance sheets Net amount Financial instruments Cash collateral pledged Liability Derivatives: Zero cost collars $ 257 $ — $ 257 $ — $ (340 ) $ (83 ) Forward $ 1,174 $ — $ 1,174 $ — $ (1,330 ) $ (156 )
Offsetting of Derivative Assets	Offsetting of derivative assets as of December 31, 2017 is as follows (in thousands): As of December 31, 2017 Gross amounts of recognized assets Gross amounts offset in the balance sheets Net amounts of assets presented in the balance sheets Gross amounts not offset in the balance sheets Net amount Financial instruments Cash collateral pledged Asset Derivatives: Zero cost collars $ 2,827 $ — $ 2,827 $ — $ — $ 2,827 Forward $ 2,352 $ — $ 2,352 $ — $ — $ 2,352
Impact of Derivative Instruments on Consolidated Statement of Operations	The following table summarizes the impact of derivative instruments on the consolidated statement of operations for the three months ended September 30, 2018 and 2017 (in thousands): Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion) Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion) Location of Gain (Loss) Recognized in Statement of Operations on Derivative (Ineffective Portion) Amount of Gain Statement of Operations on Derivatives (Ineffective Portion) Three Months Ended September 30, Three Months Ended September 30, Three Months Ended September 30, 2018 2017 2018 2017 2018 2017 Zero cost collars $ 386 $ (217 ) Net sales $ — $ — Other income (expenses), net $ 18 $ (142 ) Forwards $ 660 $ 24 Net sales $ (140 ) $ 42 Other income (expenses), net $ (536 ) $ (228 ) Total $ 1,046 $ (193 ) $ (140 ) $ 42 $ (518 ) $ (370 ) The following table summarizes the impact of derivative instruments on the consolidated statement of operations for the nine months ended September 30, 2018 and 2017 (in thousands): Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion) Location of Gain Reclassified from AOCI into Statement of Operations (Effective Portion) Amount of Gain Reclassified from AOCI into Statement of Operations (Effective Portion) Location of Gain (Loss) Recognized in Statement of Operations on Derivative (Ineffective Portion) Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion) Nine Months Ended September 30, Nine Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 2018 2017 Zero cost collars $ (756 ) $ 666 Net sales $ 2,191 $ 1,305 Other income (expenses), net $ (300 ) $ 127 Forwards $ (136 ) $ 50 Net sales $ 2,310 $ 42 Other income (expenses), net $ (1,926 ) $ (327 ) Total $ (892 ) $ 716 $ 4,501 $ 1,347 $ (2,226 ) $ (200 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Financial Assets Measured at Fair Value on Recurring Basis	As of September 30, 2018, the following table represents the Company’s liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value September 30, 2018 Fair Value Measurement September 30, 2018 Quoted Prices in Active Markets for Identical Asset (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Liabilities: Derivative liabilities (other current liabilities) $ 1,431 $ 1,431 — $ 1,431 — As of December 31, 2017, the following table represents the Company’s assets measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value December 31, 2017 Fair Value Measurement December 31, 2017 Quoted Prices in Active Markets for Identical Asset (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Derivative assets (other current assets) $ 5,179 $ 5,179 — $ 5,179 —
Schedule of Fair Value of Long-term Borrowings	Fair Value of Long-term Borrowings September 30, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value (In thousands of US dollars) Long-term Borrowings: 5.0% Exchangeable Senior Notes due March 2021 (Level 2) $ 82,593 $ 129,778 $ 81,576 $ 127,617 6.625% Senior Notes due July 2021 (Level 2) $ 222,446 $ 222,244 $ 221,840 $ 224,719

Long-Term Borrowings (Tables)

Long-Term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Components of Long-term Borrowings	Long-term borrowings as of September 30, 2018 and December 31, 2017 are as follows (in thousands): September 30, 2018 December 31, 2017 5.0% Exchangeable Senior Notes due March 2021 $ 86,250 $ 86,250 6.625% Senior Notes due July 2021 $ 225,000 $ 225,000 Less: unamortized discount and debt issuance costs (6,211 ) (7,834 ) Long-term borrowings, net of unamortized discount and debt issuance costs $ 305,039 $ 303,416

Accrued Severance Benefits (Tab

Accrued Severance Benefits (Tables)	9 Months Ended
	Sep. 30, 2018
Postemployment Benefits [Abstract]
Changes in Accrued Severance Benefits	Changes in accrued severance benefits are as follows (in thousands): Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 Beginning balance $ 146,375 $ 149,795 $ 130,894 $ 130,144 Provisions 5,521 14,686 4,578 15,354 Severance payments (3,250 ) (9,004 ) (1,496 ) (19,578 ) Translation adjustments 1,194 (5,637 ) (852 ) 7,204 149,840 149,840 133,124 133,124 Less: Cumulative contributions to severance insurance deposit accounts (858 ) (858 ) — — The National Pension Fund (236 ) (236 ) (243 ) (243 ) Group severance insurance plan (598 ) (598 ) (593 ) (593 ) Accrued severance benefits, net $ 148,148 $ 148,148 $ 132,288 $ 132,288
Future Benefits Payments to Employees	The Company is liable to pay the following future benefits to its non-executive Severance benefit Remainder of 2018 $ — 2019 598 2020 1,092 2021 1,569 2022 1,343 2023 1,836 2024 – 2028 27,152

Geographic and Segment Inform_2

Geographic and Segment Information (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Operating Segments	The following sets forth information relating to the operating segment (in thousands): Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 As Adjusted September 30, 2018 September 30, 2017 As Adjusted Net Sales Foundry Services Group $ 83,862 $ 89,004 $ 242,198 $ 260,095 Standard Products Group Display Solutions 77,578 48,636 205,986 135,233 Power Solutions 44,458 39,001 123,153 109,595 Total Standard Products Group 122,036 87,637 329,139 244,828 All other 102 56 167 169 Total net sales $ 206,000 $ 176,697 $ 571,504 $ 505,092 Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 As Adjusted September 30, 2018 September 30, 2017 As Adjusted Gross Profit Foundry Services Group $ 20,443 $ 26,344 $ 63,292 $ 74,326 Standard Products Group 35,204 23,910 90,874 64,047 All other 102 56 18 169 Total gross profit $ 55,749 $ 50,310 $ 154,184 $ 138,542
Summary of Revenue Disaggregated Depending on Timing of Revenue Recognition	Upon the adoption of the new revenue standard, the Company’s revenue for Foundry Services Group is disaggregated depending on the timing of revenue recognition (in thousands): Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Revenue recognized at the time of shipment or delivery Revenue recognized over time Total Revenue recognized at the time of shipment or delivery Revenue recognized over time Total Net Sales Foundry Services Group $ 26,257 $ 57,605 $ 83,862 $ 52,024 $ 190,174 $ 242,198
Net Sales by Region, Based on Location of Products are Billed	The following is a summary of net sales by geographic region, based on the location to which the products are billed (in thousands): Three Months Ended September 30, 2018 September 30, 2017 Korea $ 91,570 $ 74,327 Asia Pacific (other than Korea) 93,475 83,221 U.S.A. 5,831 8,399 Europe 14,444 10,492 Others 680 258 Total $ 206,000 $ 176,697 Nine Months Ended September 30, 2018 September 30, 2017 Korea $ 204,319 $ 207,389 Asia Pacific (other than Korea) 302,906 239,209 U.S.A. 29,242 28,721 Europe 33,041 29,070 Others 1,996 703 Total $ 571,504 $ 505,092

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	Accumulated other comprehensive loss consists of the following as of September 30, 2018 and December 31, 2017, respectively (in thousands): September 30, 2018 December 31, 2017 Foreign currency translation adjustments $ (22,607 ) $ (38,413 ) Derivative adjustments (93 ) 5,299 Total $ (22,700 ) $ (33,114 )
Changes in Accumulated Other Comprehensive Loss	Changes in accumulated other comprehensive loss for the three months ended September 30, 2018 and 2017 are as follows (in thousands): Three Months Ended September 30, 2018 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ (18,780 ) $ (1,279 ) $ (20,059 ) Other comprehensive income (loss) before reclassifications (3,827 ) 1,046 (2,781 ) Amounts reclassified from accumulated other comprehensive loss — 140 140 Net current-period other comprehensive income (loss) (3,827 ) 1,186 (2,641 ) Ending balance $ (22,607 ) $ (93 ) $ (22,700 ) Three Months Ended September 30, 2017 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ (11,502 ) $ (832 ) $ (12,334 ) Other comprehensive income (loss) before reclassifications 2,692 (193 ) 2,499 Amounts reclassified from accumulated other comprehensive income — (42 ) (42 ) Net current-period other comprehensive income (loss) 2,692 (235 ) 2,457 Ending balance $ (8,810 ) $ (1,067 ) $ (9,877 ) Changes in accumulated other comprehensive loss for the nine months ended September 30, 2018 and 2017 are as follows (in thousands): Nine Months Ended September 30, 2018 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ (38,413 ) $ 5,299 $ (33,114 ) Other comprehensive income (loss) before reclassifications 15,806 (891 ) 14,915 Amounts reclassified from accumulated other comprehensive income — (4,501 ) (4,501 ) Net current-period other comprehensive income (loss) 15,806 (5,392 ) 10,414 Ending balance $ (22,607 ) $ (93 ) $ (22,700 ) Nine Months Ended September 30, 2017 Foreign currency translation adjustments Derivative adjustments Total Beginning balance $ 14,460 $ (436 ) $ 14,024 Other comprehensive income (loss) before reclassifications (23,270 ) 716 (22,554 ) Amounts reclassified from accumulated other comprehensive income — (1,347 ) (1,347 ) Net current-period other comprehensive loss (23,270 ) (631 ) (23,901 ) Ending balance $ (8,810 ) $ (1,067 ) $ (9,877 )

Earnings (Loss) per Share (Tabl

Earnings (Loss) per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings Per Common Share	The following table illustrates the computation of basic and diluted earnings (loss) per common share for the three and nine months ended September 30, 2018 and 2017: Three Months Ended September 30, 2018 September 30, 2017 (In thousands of US dollars, except share data) Basic Earnings per Share Net income $ 17,222 $ 5,604 Basic weighted average common stock outstanding 34,573,377 34,103,029 Basic earnings per share $ 0.50 $ 0.16 Diluted Earnings per Share Net income $ 17,222 $ 5,604 Add back: Interest expense on Exchangeable Notes 1,422 1,400 Net income allocated to common stockholders $ 18,644 $ 7,004 Basic weighted average common stock outstanding 34,573,377 34,103,029 Net effect of dilutive equity awards 1,000,020 991,176 Net effect of assumed conversion of 5.0% Exchangeable Notes to common stock 10,448,213 10,448,213 Diluted weighted average common stock outstanding 46,021,610 45,542,418 Diluted earnings per share $ 0.41 $ 0.15 Nine Months Ended September 30, 2018 September 30, 2017 (In thousands of US dollars, except share data) Basic Earnings (Loss) per Share Net income (loss) $ (1,520 ) $ 41,283 Basic weighted average common stock outstanding 34,416,887 33,907,581 Basic earnings (loss) per share $ (0.04 ) $ 1.22 Diluted Earnings (Loss) per Share Net income (loss) $ (1,520 ) $ 41,283 Add back: Interest expense on Exchangeable Notes — 3,942 Net income allocated to common stockholders $ (1,520 ) $ 45,225 Basic weighted average common stock outstanding 34,416,887 33,907,581 Net effect of dilutive equity awards — 695,427 Net effect of assumed conversion of 5.0% Exchangeable Notes to common stock — 9,835,863 Diluted weighted average common stock outstanding 34,416,887 44,438,871 Diluted earnings (loss) per share $ (0.04 ) $ 1.02
Schedule of Antidilutive Securities Excluded from the Computation of Earnings Per Common Share	The following outstanding instruments were excluded from the computation of diluted earnings (loss) per share, as they have an anti-dilutive effect on the calculation: Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Options 723,117 809,417 2,684,558 860,572 Restricted Stock Units — — 581,759 —

Business, Basis of Presentati_4

Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)SegmentsBusiness_Lines	Sep. 30, 2017USD ($)	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | Segments		2
Payment terms, description		The standard payment terms with customers is generally thirty to sixty days from the time of shipment, product delivery at the customer’s location or customer acceptance, depending on the terms of the related arrangement.
Contract duration, description		Substantially all of the Company’s contracts are one year or less in duration.
Restricted cash, cash and cash equivalents	$ 133,482	$ 133,482	$ 128,425		$ 128,575	$ 101,606
Restricted cash						18,251
Net cash (used in) provided by operating activities		25,014	(24,314)
Net cash (used in) provided by investing activities		(21,257)	(23,992)
Effect of exchange rates on cash, cash equivalents and restricted cash		4,907	26,819
Unbilled accounts receivable	35,837	35,837		$ 38,307
Inventories, net	(71,532)	(71,532)			(73,073)
Total stockholders' equity (deficit)	(17,452)	(17,452)	(61,128)		(39,637)	$ (72,114)
Amounts billed to customers	871	35,909
Deferred revenue	11,682	11,682			$ 8,335
Deferred revenue recognized	2,256	$ 3,478
Minimum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Payment terms		30 days
Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Payment terms		60 days
Contract duration		1 year
ASU 2016-18 [Member] | Restatement Adjustment [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Restricted cash, cash and cash equivalents			18,251
Net cash (used in) provided by operating activities			(1,809)
Net cash (used in) provided by investing activities			(17,625)
Effect of exchange rates on cash, cash equivalents and restricted cash			$ 1,183
Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Unbilled accounts receivable	35,837	$ 35,837		38,307
Inventories, net	27,675	27,675		29,823
Total stockholders' equity (deficit)	$ 8,162	$ 8,162		$ 8,484
Standard Products Group [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of business lines | Business_Lines		2

Business, Basis of Presentati_5

Business, Basis of Presentation and Significant Accounting Policies - Summary of Consolidated Statement of Balance Sheet Line Items, which Reflect Adoption of New Revenue Recognition Guidance (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current assets
Unbilled accounts receivable	$ 35,837	$ 38,307
Inventories, net	71,532		$ 73,073
Total current assets	384,744		330,260
Total assets	612,706		558,789
Stockholders' equity
Accumulated deficit	(33,925)		(40,889)
Accumulated other comprehensive loss	(22,700)		(33,114)
Total stockholders' deficit	(17,452)		(39,637)	$ (61,128)	$ (72,114)
Total liabilities and stockholders' deficit	612,706		$ 558,789
Adjustments [Member] | Accounting Standards Update 2014-09 [Member]
Current assets
Unbilled accounts receivable	35,837	38,307
Inventories, net	(27,675)	(29,823)
Total current assets	8,162
Total assets	8,162
Stockholders' equity
Accumulated deficit	8,505
Accumulated other comprehensive loss	(343)
Total stockholders' deficit	8,162	$ 8,484
Total liabilities and stockholders' deficit	8,162
Amounts Without Adoption of the New Revenue Standard [Member] | Accounting Standards Update 2014-09 [Member]
Current assets
Inventories, net	99,207
Total current assets	376,582
Total assets	604,544
Stockholders' equity
Accumulated deficit	(42,430)
Accumulated other comprehensive loss	(22,357)
Total stockholders' deficit	(25,614)
Total liabilities and stockholders' deficit	$ 604,544

Business, Basis of Presentati_6

Business, Basis of Presentation and Significant Accounting Policies - Summary of Consolidated Statement of Operations Line Items, which Reflect Adoption of New Revenue Recognition Guidance (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	$ 206,000	$ 176,697	$ 571,504	$ 505,092
Cost of sales	150,251	126,387	417,320	366,550
Gross profit	55,749	50,310	154,184	138,542
Operating income	18,265	15,490	39,558	31,599
Income before income tax expenses	18,830	6,541	2,599	43,611
Net income (loss)	$ 17,222	$ 5,604	$ (1,520)	$ 41,283
Earnings (loss) per common share-
Basic	$ 0.50	$ 0.16	$ (0.04)	$ 1.22
Diluted	$ 0.41	$ 0.15	$ (0.04)	$ 1.02
Adjustments [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	$ (299)		$ (1,186)
Cost of sales	803		(1,207)
Gross profit	(1,102)		21
Operating income	(1,102)		21
Income before income tax expenses	(1,102)		21
Net income (loss)	$ (1,102)		21
Earnings (loss) per common share-
Basic	$ (0.03)
Diluted	$ (0.02)
Amounts Without Adoption of the New Revenue Standard [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	$ 206,299		572,690
Cost of sales	149,448		418,527
Gross profit	56,851		154,163
Operating income	19,367		39,537
Income before income tax expenses	19,932		2,578
Net income (loss)	$ 18,324		$ (1,541)
Earnings (loss) per common share-
Basic	$ 0.53		$ (0.04)
Diluted	$ 0.43		$ (0.04)

Sales of Accounts Receivable _2

Sales of Accounts Receivable and Receivable Discount Program - Additional Information (Detail) - Trade Accounts Receivable [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of accounts receivable	$ 17,156	$ 16,180
Selling, General and Administrative Expenses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pre-tax losses on accounts receivable	$ 35	$ 47

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Finished goods	$ 11,799		$ 13,737
Semi-finished goods and work-in-process	42,322		53,148
Raw materials	17,469		12,445
Materials in-transit	3,792		134
Less: inventory reserve	(3,850)	$ (4,699)	(6,391)	$ (6,089)	$ (5,297)	$ (7,177)
Inventories, net	$ 71,532		$ 73,073

Inventories - Changes in Invent

Inventories - Changes in Inventory Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Inventory Disclosure [Abstract]
Beginning balance	$ (4,699)	$ (5,297)	$ (6,391)	$ (7,177)
Inventory reserve charged to costs of sales	(980)	(2,084)	(2,837)	(3,479)
Sale of previously reserved inventory	1,208	816	1,681	3,380
Change in reserve	228	(1,268)	(1,156)	(99)
Write off	656	433	3,497	1,584
Translation adjustments	(35)	43	200	(397)
Ending balance	$ (3,850)	$ (6,089)	$ (3,850)	$ (6,089)

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 430,022	$ 421,168
Less: accumulated depreciation	(245,122)	(231,356)
Property, plant and equipment, net	200,393	205,903
Buildings and Related Structures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	70,840	69,958
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	313,611	308,713
Others [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	45,571	42,497
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 15,493	$ 16,091

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 29, 2018	Sep. 30, 2018	Sep. 30, 2017
Property, Plant and Equipment [Line Items]
Depreciation expenses		$ 23,272	$ 20,224
Water Treatment Facilities [Member]
Property, Plant and Equipment [Line Items]
Business acquisition, assets acquired and liabilities assumed, net	$ 4,172
Net proceeds from sale leaseback facility, financing activities	$ 4,172
Sale leaseback facility, financing activities, term	10 years
Business acquisition, other current liabilities	$ 553
Business acquisition, other non-current liabilities	$ 3,619

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	$ 58,818	$ 60,515
Accumulated amortization	(54,823)	(56,454)
Intangible asset, Net amount	3,995	4,061
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	19,444	20,194
Accumulated amortization	(19,444)	(20,194)
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	27,926	29,002
Accumulated amortization	(27,926)	(29,002)
Intellectual Property Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	11,448	11,319
Accumulated amortization	(7,453)	(7,258)
Intangible asset, Net amount	$ 3,995	$ 4,061

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense for intangible assets	$ 611	$ 465

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Payroll, benefits and related taxes, excluding severance benefits	$ 19,237	$ 16,724
Withholding tax attributable to intercompany interest income	20,062	18,138
Interest on senior notes	3,463	8,268
Outside service fees	1,272	1,942
Others	1,607	6,674
Accrued expenses	$ 45,641	$ 51,746

Derivative Financial Instrume_3

Derivative Financial Instruments - Details of Derivative Contracts (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Zero Cost Collar One [Member]
Derivative [Line Items]
Date of transaction	Jun. 18, 2018	Jun. 22, 2017
Type of derivative	Zero cost collar	Zero cost collar
Total notional amount	$ 15,000,000	$ 20,000,000
Month of settlement, start	2018-10	2018-01
Month of settlement, end	2018-12	2018-02
Zero Cost Collar Two [Member]
Derivative [Line Items]
Date of transaction	Jun. 27, 2018	Sep. 28, 2017
Type of derivative	Zero cost collar	Zero cost collar
Total notional amount	$ 27,000,000	$ 54,000,000
Month of settlement, start	2018-10	2018-01
Month of settlement, end	2019-06	2018-06
Forward [Member]
Derivative [Line Items]
Date of transaction	Jun. 18, 2018	Sep. 28, 2017
Type of derivative	Forward	Forward
Total notional amount	$ 30,000,000	$ 36,000,000
Month of settlement, start	2018-10	2018-01
Month of settlement, end	2018-12	2018-06
Forward One [Member]
Derivative [Line Items]
Date of transaction	Jun. 27, 2018
Type of derivative	Forward
Total notional amount	$ 48,000,000
Month of settlement, start	2018-10
Month of settlement, end	2019-06

Derivative Financial Instrume_4

Derivative Financial Instruments - Fair Values of Outstanding Zero Cost Collar and Forward Contracts Recorded as Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Zero Cost Collars [Member]
Asset Derivatives:
Derivatives designated as hedging instruments, Asset		$ 2,827
Liability Derivatives:
Other current liabilities	$ 257
Forward [Member]
Asset Derivatives:
Derivatives designated as hedging instruments, Asset		2,352
Liability Derivatives:
Other current liabilities	1,174
Other Current Assets [Member] | Zero Cost Collars [Member]
Asset Derivatives:
Derivatives designated as hedging instruments, Asset		2,827
Other Current Assets [Member] | Forward [Member]
Asset Derivatives:
Derivatives designated as hedging instruments, Asset		$ 2,352
Other Current Liabilities [Member] | Zero Cost Collars [Member]
Liability Derivatives:
Other current liabilities	257
Other Current Liabilities [Member] | Forward [Member]
Liability Derivatives:
Other current liabilities	$ 1,174

Derivative Financial Instrume_5

Derivative Financial Instruments - Offsetting of Derivative Liabilities and Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Zero Cost Collars [Member]
Derivative [Line Items]
Liability Derivatives, Gross amounts of recognized liabilities	$ 257
Liability Derivatives, Gross amounts offset in the balance sheets	0
Liability Derivatives, Net amounts of liabilities presented in the balance sheets	257
Liability Derivatives, Gross amounts not offset in the balance sheets, Financial instruments	0
Liability Derivatives, Gross amounts not offset in the balance sheets, Cash collateral pledged	(340)
Liability Derivatives, Net amount after master netting	(83)
Asset Derivatives, Gross amounts of recognized assets		$ 2,827
Asset Derivatives, Gross amounts offset in the balance sheets		0
Asset Derivatives, Net amounts of assets presented in the balance sheets		2,827
Asset Derivatives, Gross amounts not offset in the balance sheets, Financial instruments		0
Asset Derivatives, Gross amounts not offset in the balance sheets, Cash collateral pledged		0
Asset Derivatives, Net amount		2,827
Forward [Member]
Derivative [Line Items]
Liability Derivatives, Gross amounts of recognized liabilities	1,174
Liability Derivatives, Gross amounts offset in the balance sheets	0
Liability Derivatives, Net amounts of liabilities presented in the balance sheets	1,174
Liability Derivatives, Gross amounts not offset in the balance sheets, Financial instruments	0
Liability Derivatives, Gross amounts not offset in the balance sheets, Cash collateral pledged	(1,330)
Liability Derivatives, Net amount after master netting	$ (156)
Asset Derivatives, Gross amounts of recognized assets		2,352
Asset Derivatives, Gross amounts offset in the balance sheets		0
Asset Derivatives, Net amounts of assets presented in the balance sheets		2,352
Asset Derivatives, Gross amounts not offset in the balance sheets, Financial instruments		0
Asset Derivatives, Gross amounts not offset in the balance sheets, Cash collateral pledged		0
Asset Derivatives, Net amount		$ 2,352

Derivative Financial Instrume_6

Derivative Financial Instruments - Impact of Derivative Instruments on Consolidated Statement of Operations (Detail) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ 1,046	$ (193)
Other Income (Expenses) - Others [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)			$ (892)	$ 716
Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(518)	(370)	(2,226)	(200)
Net Sales [Member]
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	(140)	42	4,501	1,347
Zero Cost Collars [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	386	(217)
Zero Cost Collars [Member] | Other Income (Expenses) - Others [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)			(756)	666
Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	18	(142)	(300)	127
Zero Cost Collars [Member] | Net Sales [Member]
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion)			2,191	1,305
Forward [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	660	24
Forward [Member] | Other Income (Expenses) - Others [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)			(136)	50
Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(536)	(228)	(1,926)	(327)
Forward [Member] | Net Sales [Member]
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	$ (140)	$ 42	$ 2,310	$ 42

Derivative Financial Instrume_7

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Estimated amount reclassified from accumulated other comprehensive income into income, period	12 months
Estimated amount reclassified from accumulated other comprehensive income into income	$ 94,000
Zero Cost Collar and Forward Contracts [Member] | Nomura Financial Investment (Korea) Co., Ltd. [Member]
Derivative [Line Items]
Deposit with counterparty	5,300,000	$ 7,600,000
Threshold amount of cash collateral	500,000
Cash collateral for credit exposure in derivatives	1,670,000
Termination provisions for cash and cash equivalents	$ 30,000,000

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Carrying Value [Member] | Other Current Assets [Member]
Assets:
Derivative assets		$ 5,179
Carrying Value [Member] | Other Current Liabilities [Member]
Liabilities:
Derivative liabilities	$ 1,431
Estimate of Fair Value Measurement [Member] | Other Current Assets [Member]
Assets:
Derivative assets		5,179
Estimate of Fair Value Measurement [Member] | Other Current Liabilities [Member]
Liabilities:
Derivative liabilities	1,431
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Assets [Member]
Assets:
Derivative assets		$ 5,179
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Other Current Liabilities [Member]
Liabilities:
Derivative liabilities	$ 1,431

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Long-term Borrowings:
Carrying amount of senior notes	$ 305,039	$ 303,416
5.0% Exchangeable Senior Notes due March 2021 [Member] | Exchangeable Senior Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]
Long-term Borrowings:
Carrying amount of senior notes	82,593	81,576
Estimated fair value of senior notes	129,778	127,617
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member] | Significant Other Observable Inputs (Level 2) [Member]
Long-term Borrowings:
Carrying amount of senior notes	222,446	221,840
Estimated fair value of senior notes	$ 222,244	$ 224,719

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Fair Value of Long-term Borrowings (Parenthetical) (Detail)	Jan. 17, 2017	Jul. 18, 2013	Sep. 30, 2018	Dec. 31, 2017
5.0% Exchangeable Senior Notes due March 2021 [Member] | Exchangeable Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.00%		5.00%	5.00%
Due date	Mar. 1, 2021		Mar. 1, 2021	Mar. 1, 2021
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate		6.625%	6.625%	6.625%
Due date		Jul. 15, 2021	Jul. 15, 2021	Jul. 15, 2021

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Jan. 17, 2017	Jul. 18, 2013	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt issuance costs paid				$ 5,902,000
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate		6.625%	6.625%		6.625%
Due date		Jul. 15, 2021	Jul. 15, 2021		Jul. 15, 2021
Aggregate principal amount		$ 225,000,000
Debt issuance costs paid		5,039,000
Original debt issue discount		$ 1,125,000
5.0% Exchangeable Senior Notes due March 2021 [Member] | Exchangeable Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	5.00%		5.00%		5.00%
Due date	Mar. 1, 2021		Mar. 1, 2021		Mar. 1, 2021
Aggregate principal amount	$ 86,250,000
Debt issuance costs paid	$ 5,902,000		$ 5,902,000
Other Asset Class [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value on non-recurring basis			0	0
Liabilities fair value on non-recurring basis			$ 0	$ 0

Long-term Borrowings - Componen

Long-term Borrowings - Components of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Less: unamortized discount and debt issuance costs	$ (6,211)	$ (7,834)
Long-term borrowings, net of unamortized discount and debt issuance costs	305,039	303,416
Exchangeable Senior Notes [Member] | 5.0% Exchangeable Senior Notes due March 2021 [Member]
Debt Instrument [Line Items]
Long-term borrowings	86,250	86,250
Senior Notes [Member] | 6.625% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term borrowings	$ 225,000	$ 225,000

Long-term Borrowings - Compon_2

Long-term Borrowings - Components of Long-term Borrowings (Parenthetical) (Detail)	Jan. 17, 2017	Jul. 18, 2013	Sep. 30, 2018	Dec. 31, 2017
5.0% Exchangeable Senior Notes due March 2021 [Member] | Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate	5.00%		5.00%	5.00%
Due date	Mar. 1, 2021		Mar. 1, 2021	Mar. 1, 2021
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate		6.625%	6.625%	6.625%
Due date		Jul. 15, 2021	Jul. 15, 2021	Jul. 15, 2021

Long-Term Borrowings - Addition

Long-Term Borrowings - Additional Information (Detail) - USD ($)	Jan. 17, 2017	Jul. 18, 2013	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Repurchase of common stock, shares						1,795,444
Repurchase of common stock					$ 199,000	$ 11,401,000
Debt issuance costs paid						5,902,000
Interest expense related to the Exchangeable Notes			$ 1,422,000	$ 1,400,000		3,942,000
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount		$ 225,000,000
Interest rate		6.625%	6.625%		6.625%		6.625%
Due date		Jul. 15, 2021			Jul. 15, 2021		Jul. 15, 2021
Aggregate principal amount of senior notes pricing		99.50%
Debt issuance costs paid		$ 5,039,000
Interest expense related to the Exchangeable Notes			$ 3,933,000	3,918,000	$ 11,785,000	11,744,000
Original debt issue discount		$ 1,125,000
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member] | 2017 [Member]
Debt Instrument [Line Items]
Redemption price plus accrued, unpaid interest and special interest to the date of redemption					101.656%
6.625% Senior Notes Due 2021 [Member] | Senior Notes [Member] | 2018 [Member]
Debt Instrument [Line Items]
Redemption price plus accrued, unpaid interest and special interest to the date of redemption					100.00%
5.0% Exchangeable Senior Notes due March 2021 [Member] | Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 86,250,000
Interest rate	5.00%		5.00%		5.00%		5.00%
Due date	Mar. 1, 2021				Mar. 1, 2021		Mar. 1, 2021
Aggregate principal amount of senior notes pricing	5.00%
Convertible notes principal amount denomination value					$ 1,000
Conversion of converted notes, shares issued					121.1387
Exchange price			$ 8.26		$ 8.26
Redemption price plus accrued, unpaid interest and special interest to the date of redemption					100.00%
Minimum required percentage of holders to declare repurchase of notes					25.00%
Percentage of notes to repurchased on declaration by minimum required holders					100.00%
Debt issuance costs paid	$ 5,902,000				$ 5,902,000
Interest expense related to the Exchangeable Notes			$ 1,422,000	$ 1,400,000	$ 4,251,000	$ 3,942,000

Accrued Severance Benefits - Ad

Accrued Severance Benefits - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018
Percentage of employees eligible for severance benefits	98.00%
Korea [Member] | Maximum [Member]
Retirement age of employees	60 years

Accrued Severance Benefits - Ch

Accrued Severance Benefits - Changes in Accrued Severance Benefits (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Postemployment Benefits [Abstract]
Beginning balance	$ 146,375	$ 130,894	$ 149,795	$ 130,144
Provisions	5,521	4,578	14,686	15,354
Severance payments	(3,250)	(1,496)	(9,004)	(19,578)
Translation adjustments	1,194	(852)	(5,637)	7,204
Ending balance	149,840	133,124	149,840	133,124
Less: Cumulative contributions to severance insurance deposit accounts	(858)		(858)
The National Pension Fund	(236)	(243)	(236)	(243)
Group severance insurance plan	(598)	(593)	(598)	(593)
Accrued severance benefits, net	$ 148,148	$ 132,288	$ 148,148	$ 132,288	$ 148,905

Accrued Severance Benefits - Fu

Accrued Severance Benefits - Future Benefits Payments to Employees (Detail) $ in Thousands	Sep. 30, 2018USD ($)
Retirement Benefits [Abstract]
Remainder of 2018	$ 0
2,019	598
2,020	1,092
2,021	1,569
2,022	1,343
2,023	1,836
2024 - 2028	$ 27,152

Foreign Currency Gain, (Loss),

Foreign Currency Gain, (Loss), Net - Additional Information (Detail) $ in Thousands	Sep. 30, 2018USD ($)₩ / $	Dec. 31, 2017USD ($)₩ / $
Foreign Currency Transaction [Abstract]
Exchange rates using first base rate | ₩ / $	1,112.7	1,071.4
Intercompany loan balances | $	$ 680,442	$ 677,267

Restructuring and Other Gain -

Restructuring and Other Gain - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restricted cash		$ 18,251
Gain on sale of machinery and building as part of restructuring				$ 17,010
Sensor Business [Member]
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of business	$ 1,295
Net gain on sale of business	$ 375
Korea [Member] | Buildings [Member]
Restructuring Cost and Reserve [Line Items]
Gross proceeds from sale of building		18,204
Value-added tax, for sale of the building		1,655
Restricted cash		18,204
Deposits received		$ 16,549
Decrease in restricted cash due to release			$ 18,204
Korea [Member] | Buildings [Member] | Restructuring Gain [Member]
Restructuring Cost and Reserve [Line Items]
Gain on sale of machinery and building as part of restructuring			$ 16,635

Early Termination Charges - Add

Early Termination Charges - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)Employee_Position	Mar. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Restructuring Cost and Reserve [Line Items]
Early termination charges			$ 13,369
Headcount Reduction Plan [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments				$ 31,000
Early termination charges	$ 2,262	$ 11,107
Number of employees elected to resign | Employee_Position	352

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expenses (benefits)	$ 1,608	$ 937	$ 4,119	$ 2,328
Net operating loss carryforward, utilization limitation	70.00%		70.00%
Statutory income tax rate			21.00%		35.00%

Geographic and Segment Inform_3

Geographic and Segment Information - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)Customer	Sep. 30, 2017USD ($)Customer	Sep. 30, 2018USD ($)CustomerSegments	Sep. 30, 2017USD ($)Customer
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | Segments			2
Total net sales	$ 206,000	$ 176,697	$ 571,504	$ 505,092
Total gross profit	55,749	50,310	154,184	138,542
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	91,570	74,327	204,319	207,389
Operating Segments [Member] | Standard Products Group [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	122,036	87,637	329,139	244,828
Total gross profit	$ 35,204	23,910	$ 90,874	64,047
Operating Segments [Member] | Restatement Adjustment [Member] | Standard Products Group [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales		8,600		20,635
Total gross profit		$ 1,970		$ 4,432
Geographic Concentration Risk [Member] | Property, Plant and Equipment [Member] | Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage			97.00%
Geographic Concentration Risk [Member] | Net Sales [Member] | China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	64.10%	47.90%	67.60%	49.50%
Geographic Concentration Risk [Member] | Net Sales [Member] | Taiwan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	29.70%	40.70%	25.80%	35.10%
Customer Concentration Risk [Member] | Net Sales [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of customers greater than ten percent threshold | Customer	2	1	2	1
Customer Concentration Risk [Member] | Net Sales [Member] | Top Ten Customers [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	65.00%	58.00%	62.00%	59.00%
Number of customers | Customer	10	10	10	10
Customer Concentration Risk [Member] | Net Sales [Member] | Top Customer One [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	18.80%	16.90%	21.60%	15.60%
Customer Concentration Risk [Member] | Net Sales [Member] | Top Customer Two [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	17.60%		13.00%

Geographic and Segment Inform_4

Geographic and Segment Information - Schedule of Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total net sales	$ 206,000	$ 176,697	$ 571,504	$ 505,092
Total gross profit	55,749	50,310	154,184	138,542
Operating Segments [Member] | Foundry Services Group [Member]
Segment Reporting Information [Line Items]
Total net sales	83,862	89,004	242,198	260,095
Total gross profit	20,443	26,344	63,292	74,326
Operating Segments [Member] | Standard Products Group [Member]
Segment Reporting Information [Line Items]
Total net sales	122,036	87,637	329,139	244,828
Total gross profit	35,204	23,910	90,874	64,047
Operating Segments [Member] | Standard Products Group [Member] | Display Solutions [Member]
Segment Reporting Information [Line Items]
Total net sales	77,578	48,636	205,986	135,233
Operating Segments [Member] | Standard Products Group [Member] | Power Solutions [Member]
Segment Reporting Information [Line Items]
Total net sales	44,458	39,001	123,153	109,595
All Other [Member]
Segment Reporting Information [Line Items]
Total net sales	102	56	167	169
Total gross profit	$ 102	$ 56	$ 18	$ 169

Geographic and Segment Inform_5

Geographic and Segment Information - Summary of Revenue Disaggregated Depending on Timing of Revenue Recognition (Detail) - Foundry Services Group [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total	$ 83,862	$ 242,198
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total	26,257	52,024
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total	$ 57,605	$ 190,174

Geographic and Segment Inform_6

Geographic and Segment Information - Net Sales by Region, Based on Location of Products are Billed (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	$ 206,000	$ 176,697	$ 571,504	$ 505,092
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	91,570	74,327	204,319	207,389
Asia Pacific (Other Than Korea) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	93,475	83,221	302,906	239,209
U.S.A. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	5,831	8,399	29,242	28,721
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	14,444	10,492	33,041	29,070
Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	$ 680	$ 258	$ 1,996	$ 703

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Foreign currency translation adjustments	$ (22,607)	$ (38,413)
Derivative adjustments	(93)	5,299
Total	$ (22,700)	$ (33,114)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning			$ (39,637)	$ (72,114)
Net current-period other comprehensive income (loss)	$ (2,641)	$ 2,457	10,414	(23,901)
Balance, ending	(17,452)	(61,128)	(17,452)	(61,128)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	(18,780)	(11,502)	(38,413)	14,460
Other comprehensive income (loss) before reclassifications	(3,827)	2,692	15,806	(23,270)
Net current-period other comprehensive income (loss)	(3,827)	2,692	15,806	(23,270)
Balance, ending	(22,607)	(8,810)	(22,607)	(8,810)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	(1,279)	(832)	5,299	(436)
Other comprehensive income (loss) before reclassifications	1,046	(193)	(891)	716
Amounts reclassified from accumulated other comprehensive income	140	(42)	(4,501)	(1,347)
Net current-period other comprehensive income (loss)	1,186	(235)	(5,392)	(631)
Balance, ending	(93)	(1,067)	(93)	(1,067)
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	(20,059)	(12,334)	(33,114)	14,024
Other comprehensive income (loss) before reclassifications	(2,781)	2,499	14,915	(22,554)
Amounts reclassified from accumulated other comprehensive income	140	(42)	(4,501)	(1,347)
Net current-period other comprehensive income (loss)	(2,641)	2,457	10,414	(23,901)
Balance, ending	$ (22,700)	$ (9,877)	$ (22,700)	$ (9,877)

Accumulated Other Comprehensi_5

Accumulated Other Comprehensive Income (Loss) - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Income tax related to accumulated other comprehensive income (loss)	$ 0	$ 0

Earnings (Loss) per Share - Sch

Earnings (Loss) per Share - Schedule of Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income (loss)	$ 17,222	$ 5,604	$ (1,520)	$ 41,283
Basic weighted average common stock outstanding	34,573,377	34,103,029	34,416,887	33,907,581
Basic earnings (loss) per share	$ 0.50	$ 0.16	$ (0.04)	$ 1.22
Diluted Earnings (Loss) per Share
Net income (loss)	$ 17,222	$ 5,604	$ (1,520)	$ 41,283
Add back: Interest expense on Exchangeable Notes	1,422	1,400		3,942
Net income allocated to common stockholders	$ 18,644	$ 7,004	$ (1,520)	$ 45,225
Basic weighted average common stock outstanding	34,573,377	34,103,029	34,416,887	33,907,581
Net effect of dilutive equity awards	1,000,020	991,176		695,427
Net effect of assumed conversion of 5.0% Exchangeable Notes to common stock	10,448,213	10,448,213		9,835,863
Diluted weighted average common stock outstanding	46,021,610	45,542,418	34,416,887	44,438,871
Diluted earnings (loss) per share	$ 0.41	$ 0.15	$ (0.04)	$ 1.02

Earnings (Loss) per Share - S_2

Earnings (Loss) per Share - Schedule of Computation of Basic and Diluted Earnings Per Common Share (Parenthetical) (Detail)	Sep. 30, 2018	Dec. 31, 2017	Jan. 17, 2017
5.0% Exchangeable Senior Notes due March 2021 [Member] | Exchangeable Senior Notes [Member]
Earnings Per Share [Line Items]
Conversion of exchangeable notes to common stock rate	5.00%	5.00%	5.00%

Earnings per (Loss) Share - Sch

Earnings per (Loss) Share - Schedule of Antidilutive Securities Excluded from the Computation of Earnings Per Common Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding units and warrants excluded from computation of diluted loss per share/unit	723,117	809,417	2,684,558	860,572
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding units and warrants excluded from computation of diluted loss per share/unit			581,759

Earnings (Loss) per Share - Add

Earnings (Loss) per Share - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018shares
Common Stock [Member] | Exchangeable Notes [Member]
Class of Stock [Line Items]
Conversion of exchangeable notes excluded from computation of diluted earnings per share	10,448,213

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	Oct. 18, 2016	Feb. 05, 2016	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2015
Loss Contingencies [Line Items]
Restricted cash							$ 18,251
Other Current Assets [Member]
Loss Contingencies [Line Items]
Prepayments to suppliers								$ 8,667	$ 7,404
Shareholder Derivative Actions [Member]
Loss Contingencies [Line Items]
Attorneys' fee and litigation expenses	$ 750
Settlement charge paid							2,258
Proceeds from insurance settlement						$ 3,000
Insurance proceeds in restricted cash reclassified from other receivables							(3,078)
Settlement charge paid, portion excluding interest							$ 2,250
Securities Class Action Complaints [Member]
Loss Contingencies [Line Items]
Damages sought		$ 23,500
Proceeds from insurance settlement						29,571
Insurance proceeds in restricted cash reclassified from other receivables						$ 29,571
Disbursements of accrued claims and settlements					$ 23,500
Restricted cash					$ 6,114
Securities Class Action Complaints [Member] | Accrued Expense [Member]
Loss Contingencies [Line Items]
Accrued claim settlement										$ 23,500
Securities Class Action Complaints [Member] | Other Receivables [Member]
Loss Contingencies [Line Items]
Insurance receivable										$ 29,571
Securities and Exchange Commission Actions [Member]
Loss Contingencies [Line Items]
Attorneys' fee and litigation expenses				$ 3,000
Settlement charge paid			$ 3,000