Magnachip Semiconductor (MX) 10-Q 10 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Registrant Name	Magnachip Semiconductor Corporation
Entity Central Index Key	0001325702
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock
Trading Symbol	MX
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		46,333,946
Entity File Number	001-34791
Entity Tax Identification Number	83-0406195
Entity Address, Address Line One	c/o MagnaChip Semiconductor S.A. 1
Entity Address, City or Town	Allée Scheffer
Entity Address, Postal Zip Code	L-2520
City Area Code	352
Local Phone Number	45-62-62
Document Quarterly Report	true
Document Transition Report	false
Entity Address, Country	LU

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 290,194	$ 279,940
Accounts receivable, net	52,250	64,390
Inventories, net	29,964	39,039
Other receivables	5,649	4,338
Prepaid expenses	9,136	7,332
Hedge collateral	5,250	5,250
Other current assets (Notes 10 and 18)	2,435	9,321
Total current assets	394,878	409,610
Property, plant and equipment, net	91,014	96,383
Operating lease right-of-use assets	4,592	4,632
Intangible assets, net	2,602	2,727
Long-term prepaid expenses	5,993	4,058
Deferred income taxes	42,906	44,541
Other non-current assets	9,422	9,739
Total assets	551,407	571,690
Current liabilities
Accounts payable	43,357	52,164
Other accounts payable	8,261	2,531
Accrued expenses	17,867	16,241
Accrued income taxes	1,224	12,398
Operating lease liabilities	2,352	2,210
Current portion of long-term borrowings, net		83,479
Other current liabilities (Note 10)	6,558	4,595
Total current liabilities	79,619	173,618
Accrued severance benefits, net	39,070	40,462
Non-current operating lease liabilities	2,240	2,422
Other non-current liabilities	10,131	9,588
Total liabilities	131,060	226,090
Stockholders' equity
Common stock, $0.01 par value, 150,000,000 shares authorized, 55,469,375 shares issued and 46,257,413 outstanding at March 31, 2021 and 44,943,854 shares issued and 35,783,347 outstanding at December 31, 2020	555	450
Additional paid-in capital	250,829	163,010
Retained earnings	279,361	286,834
Treasury stock, 9,211,962 shares at March 31, 2021 and 9,160,507 shares at December 31, 2020, respectively	(109,407)	(108,397)
Accumulated other comprehensive income (loss)	(991)	3,703
Total stockholders' equity	420,347	345,600
Total liabilities and stockholders' equity	$ 551,407	$ 571,690

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
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	55,469,375	44,943,854
Common stock, shares outstanding	46,257,413	35,783,347
Treasury stock, shares	9,211,962	9,160,507

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net sales	$ 123,019	$ 120,473
Cost of sales	88,637	91,343
Gross profit	34,382	29,130
Operating expenses:
Selling, general and administrative expenses	12,634	12,102
Research and development expenses	13,423	10,509
Other charges	10,416	554
Total operating expenses	36,473	23,165
Operating income (loss)	(2,091)	5,965
Interest expense	(1,041)	(5,607)
Foreign currency loss, net	(4,671)	(30,971)
Other income, net	620	838
Loss from continuing operations before income tax expense	(7,183)	(29,775)
Income tax expense	290	1,303
Loss from continuing operations	(7,473)	(31,078)
Income from discontinued operations, net of tax	0	7,329
Net loss	$ (7,473)	$ (23,749)
Basic and diluted loss per common share—
Continuing operations	$ (0.19)	$ (0.89)
Discontinued operations	0	0.21
Total	$ (0.19)	$ (0.68)
Weighted average number of shares – basic and diluted	40,292,838	34,893,157
Fab Three Foundry Services [Member]
Net sales	$ 10,113	$ 9,737
Cost of sales	9,390	9,737
Gross profit	723
Standard products business [Member]
Net sales	112,906	110,736
Cost of sales	79,247	81,606
Gross profit	$ 33,659	$ 29,130

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (7,473)	$ (23,749)
Other comprehensive income (loss)
Foreign currency translation adjustments	(2,058)	22,251
Derivative adjustments
Fair valuation of derivatives	(2,125)	(5,004)
Reclassification adjustment for loss (gain) on derivatives included in net loss	(511)	58
Total other comprehensive income (loss)	(4,694)	17,305
Total comprehensive loss	$ (12,167)	$ (6,444)

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 Income (Loss) [Member]
Balance beginning at Dec. 31, 2019	$ (14,981)		$ 439	$ 152,404	$ (58,131)	$ (107,033)	$ (2,660)
Balance, Shares beginning at Dec. 31, 2019		34,800,312
Stock-based compensation	885			885
Settlement of restricted stock units			3	(3)
Settlement of restricted stock units, Shares		308,364
Acquisition of treasury stock	(616)					(616)
Acquisition of treasury stock, Shares		(53,994)
Other comprehensive income (loss), net	17,305						17,305
Net loss	(23,749)				(23,749)
Balance ending at Mar. 31, 2020	(21,156)		442	153,286	(81,880)	(107,649)	14,645
Balance, Shares ending at Mar. 31, 2020		35,054,682
Balance beginning at Dec. 31, 2020	$ 345,600		450	163,010	286,834	(108,397)	3,703
Balance, Shares beginning at Dec. 31, 2020	35,783,347	35,783,347
Stock-based compensation	$ 1,646			1,646
Exchange of exchangeable senior notes, Shares	83,740,000	10,144,131
Exchange of exchangeable senior notes	$ 83,740		101	83,639
Exercise of stock options	2,538		2	2,536
Exercise of stock options, Shares		175,760
Settlement of restricted stock units			2	(2)
Settlement of restricted stock units, Shares		205,630
Acquisition of treasury stock	(1,010)					(1,010)
Acquisition of treasury stock, Shares		(51,455)
Other comprehensive income (loss), net	(4,694)						(4,694)
Net loss	(7,473)				(7,473)
Balance ending at Mar. 31, 2021	$ 420,347		$ 555	$ 250,829	$ 279,361	$ (109,407)	$ (991)
Balance, Shares ending at Mar. 31, 2021	46,257,413	46,257,413

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (7,473)	$ (23,749)
Adjustments to reconcile net loss to net cash provided by operating activities
Depreciation and amortization	3,448	7,935
Provision for severance benefits	1,771	5,071
Amortization of debt issuance costs and original issue discount	261	598
Loss on foreign currency, net	14,873	38,480
Restructuring and other charges	9,504	2,138
Provision for inventory reserves	1,504	570
Stock-based compensation	1,646	885
Deferred income tax assets	30	23
Others, net	124	107
Changes in operating assets and liabilities
Accounts receivable, net	9,794	(10,430)
Unbilled accounts receivable, net		6,937
Inventories	6,071	(4,863)
Other receivables	(1,438)	1,982
Other current assets	5,427	909
Accounts payable	(7,701)	1,988
Other accounts payable	(2,009)	(1,817)
Accrued expenses	(3,532)	(6,611)
Accrued income taxes	(10,700)	(274)
Other current liabilities	1,087	1,336
Other non-current liabilities	18	1,808
Payment of severance benefits	(1,493)	(2,080)
Others, net	12	125
Net cash provided by operating activities	21,224	21,068
Cash flows from investing activities
Proceeds from settlement of hedge collateral		4,239
Payment of hedge collateral		(7,841)
Purchase of property, plant and equipment	(1,082)	(3,351)
Payment for intellectual property registration	(171)	(229)
Payment of guarantee deposits	(76)
Others, net	(35)	55
Net cash used in investing activities	(1,364)	(7,127)
Cash flows from financing activities
Proceeds from exercise of stock options	2,538
Acquisition of treasury stock	(1,540)	(1,021)
Repayment of financing related to water treatment facility arrangement	(144)	(135)
Repayment of principal portion of finance lease liabilities	(16)	(60)
Net cash provided by (used in) financing activities	838	(1,216)
Effect of exchange rates on cash and cash equivalents	(10,444)	(7,089)
Net increase in cash and cash equivalents	10,254	5,636
Cash and cash equivalents
Beginning of the period	279,940	151,657
End of the period	290,194	157,293
Supplemental cash flow information
Cash paid for interest	2,094	9,522
Cash paid for income taxes	9,633	1,534
Non-cash investing activities
Property, plant and equipment additions in other accounts payable	$ 622	$ 687
Exchange of exchangeable senior notes, Shares	83,740
Acquisition Of Treasury Stock Related To Tax With holding For Share Based Compensation	$ (114)

Business, Basis of Presentation

Business, Basis of Presentation and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
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 On September 1, 2020 (the “Closing Date”), the Company completed the sale of the Company’s Foundry Services Group business and its fabrication facility located in Cheongju, Korea, known as “Fab 4” to Key Foundry Co., Ltd. (the “Buyer”), a Korean corporation, in exchange for a purchase price equal to approximately $350.6 million in cash, pursuant to the terms of a business transfer agreement (the “Business Transfer Agreement”) dated March 31, 2020 by and among the Company and Magnus Semiconductor, LLC, a Korean limited liability company (“Magnus”). The purchase price was paid in a combination of U.S. Dollars in the amount of million. The Buyer is a wholly owned subsidiary of Magnus, which was established by Alchemist Capital Partners Korea Co., Ltd. and Credian Partners, Inc. On April 20, 2020, Magnus assigned, and the Buyer assumed, all rights and obligations of Magnus under the Business Transfer Agreement. This divestiture of the Foundry Services Group business and Fab 4 was made in connection with the Company’s strategic shift of its operational focus to its standard products business. The Foundry Services Group was historically a reportable segment. The Foundry Services Group business was classified as discontinued operations in the Company’s consolidated statements of operations and excluded from both continuing operations and segment results for the three months ended March 31, 2020. Accordingly, the Company has one reportable segment, its standard products business, together with transitional foundry services associated with its fabrication facility located in Gumi, Korea, known as “Fab 3,” that it expects to perform for the Buyer for a period of up to three years from the Closing Date (the “Transitional Fab 3 Foundry Services”). The Company’s standard products business includes its Display Solutions and Power Solutions business lines. The Company’s Display Solutions products provide panel display solutions to major suppliers of large and small rigid and flexible panel displays, and mobile, automotive applications and home appliances. The Company’s Power Solutions products include discrete and integrated circuit solutions for power management in communications, consumer and industrial applications . 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 (“U.S. 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 (“ASC”) 270, “Interim Reporting” and, accordingly, do not include all of the information and note disclosures required by U.S. GAAP for complete financial statements, except for the changes below. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for a full year or for any other periods. The consolidated statement of cash flow for the three months ended March 31, 2020 has not been adjusted to separately disclose the cash flow related to discontinued operations, but the material items in the operating and investing activities of the cash flow relating to discontinued operations for the same period is disclosed in Note 3. Unless otherwise stated, information in these notes to consolidated financial statements relates to the Company’s continuing operations and excludes the discontinued operations. The December 31, 2020 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by U.S. GAAP. The interim consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K Recently Adopted Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, 2019-12”). 2019-12 2019-12 2019-12

Merger Agreement

Merger Agreement	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Merger Agreement	2. Merger Agreement On March 25, 2021, the Company, South Dearborn Limited, an exempted company incorporated in the Cayman Islands with limited liability (“Parent”), formed by an affiliate of Wise Road Capital LTD, and Michigan Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Merger Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”). The Merger Agreement provides that, among other things, Merger Sub will be merged with and into the Company (the “Merger”), with the Company continuing its corporate existence under the General Corporation Law of the State of Delaware (the “DGCL”) as the surviving corporation and becoming a wholly owned subsidiary of Parent. Pursuant to the Merger Agreement, each share of the Company’s common stock, par value per share (the “Common Stock”), issued and outstanding immediately before the effective time of the Merger (the “Effective Time”) (other than (a) shares of Common Stock owned by the Company or any of its wholly owned subsidiaries or by Parent or any of its subsidiaries immediately before the Effective Time (collectively, “Excluded Shares”) and (b) any shares of Common Stock for which the holder thereof (i) has not voted in favor of the Merger or consented to it in writing and (ii) has properly and validly exercised their statutory rights of appraisal in respect of such shares of Common Stock in accordance with Section 262 of the DGCL (collectively, “Dissenting Shares”)) will be cancelled and will cease to exist and will be automatically converted into the right to receive in cash, without interest (the “Merger Consideration”), subject to applicable withholding taxes. Consummation of the Merger is subject to certain customary closing conditions, including (i) approval of the Merger Agreement by our stockholders, (ii) the receipt of certain required or requested governmental approvals, (iii) the absence of any order or law issued, enacted or deemed applicable by certain governmental authorities specified in the Merger Agreement that makes consummation of the Merger illegal and that remains in effect (a “Prohibitive Order”), (iv) the absence of a Company Material Adverse Effect (as defined in the Merger Agreement) and (v) other customary closing conditions, including the accuracy of each party’s representations and warranties, and each party’s compliance with its obligations under the Merger Agreement (subject in the case of this clause (v) to certain materiality qualifiers). The Merger Agreement contains termination rights for each of the Company and Parent, including if (i) the consummation of the Merger does not occur by 11:59 p.m. (New York time) on September 25, 2021 (subject to extension to December 25, 2021 and again to March 25, 2022 at the option of either party if certain regulatory approvals have not been obtained by such date or certain governmental authorities specified in the Merger Agreement have issued, enacted or deemed applicable a Prohibitive Order), (ii) the Requisite Company Vote is not obtained, (iii) any of certain governmental authorities specified in the Merger Agreement issues, enacts or deems applicable after the date of the Merger Agreement a Prohibitive Order that has become final and non-appealable, non-breaching The Merger is expected to close during the second half of 2021, subject to customary closing conditions as discussed above. For the three months ended March 31, 2021, the Company incurred $9,831 thousand of professional fees and certain transaction related expenses incurred in connection with the Merger, which were recognized in other charges in the consolidated statements of operations. The foregoing description of the Merger Agreement is not complete and is qualified in its entirety by reference to the Merger Agreement, which is included as Exhibit 2.1 to this Quarterly Report on Form 10-Q.

Discontinued Operations and Ass

Discontinued Operations and Assets Held for Sale	3 Months Ended
	Mar. 31, 2021
Discontinued Operations and Assets Held for Sale [Abstract]
Discontinued Operations and Assets Held for Sale	3. Discontinued Operations and Assets Held for Sale On September 1, 2020, the Company completed the sale of the Company’s Foundry Services Group business and Fab 4. As a result of the sale of the Foundry Services Group business and Fab 4, the Company recorded a gain of $287,117 thousand and all operations from the Foundry Services Group business and Fab 4 were classified as discontinued operations for the three months ended March 31, 2020. Following the consummation of the sale, and for up to three years, the Company is expected to provide the Transitional Fab 3 Foundry Services at an agreed upon cost plus mark-up. For the periods prior to the Closing Date, revenue from providing the Transitional Fab 3 Foundry Services to the Foundry Services Group is recorded at cost on both of the continuing and discontinued businesses for comparative purposes. Cash inflows to the Company from the Buyer related to providing the Transitional Fab 3 Foundry Services was The following table summarizes the results from discontinued operations, net of tax, for the three months ended March 31, 2020. Three Months Ended March 31, (In thousands of US dollars) Revenues: Net sales – Foundry Services Group $ 86,279 Net sales – transitional Fab 3 foundry services (9,737 ) Total revenues 76,542 Cost of sales: Cost of sales – Foundry Services Group 65,583 Cost of sales – transitional Fab 3 foundry services (9,737 ) Total cost of sales 55,846 Gross profit 20,696 Operating expenses: Selling, general and administrative expenses 5,644 Research and development expenses 7,403 Restructuring and other charges 2,115 Total operating expenses 15,162 Operating income from discontinued operations 5,534 Foreign currency gain, net 2,097 Other income 107 Income from discontinued operations before income tax expense 7,738 Income tax expense 409 Income from discontinued operations, net of tax $ 7,329 For the three months ended March 31, 2020, the Company recorded $2,115 thousand in professional fees incurred in connection with the Foundry Services Group business and Fab 4, and recorded such costs as restructuring and other charges in the above. The following table provides supplemental cash flows information related to discontinued operations: Three Months Ended March 31, (In thousands of US dollars) Significant non-cash Depreciation and amortization $ 5,365 Provision for severance benefits 3,052 Stock-based compensation 123 Investing activities: Capital expenditures $ (1,479 )

Inventories

Inventories	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Inventories	4. Inventories Inventories as of March 31, 2021 and December 31, 2020 consist of the following (in thousands): March 31, December 31, Finished goods $ 4,660 $ 6,425 Semi-finished goods and work-in-process 24,449 30,968 Raw materials 6,400 6,526 Materials in-transit 736 1,021 Less: inventory reserve (6,281 ) (5,901 ) Inventories, net $ 29,964 $ 39,039 Changes in inventory reserve for the three months ended March 31, 2021 and 2020 are as follows (in thousands): Three Months Ended March 31, March 31, Beginning balance $ (5,901 ) $ (5,947 ) Change in reserve Inventory reserve charged to costs of sales (2,164 ) (1,275 ) Sale of previously reserved inventory 634 906 (1,530 ) (369 ) Write off 902 499 Translation adjustments 248 316 Reclassified to assets held for sale — 694 Ending balance $ (6,281 ) $ (4,807 ) 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	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	5. Property, Plant and Equipment Property, plant and equipment a March 31, December 31, Buildings and related structures $ 24,110 $ 24,882 Machinery and equipment 102,365 106,244 Finance lease right-of-use 330 344 Others 39,600 40,116 166,405 171,586 Less: accumulated depreciation (89,948 ) (90,370 ) Land 14,557 15,167 Property, plant and equipment, net $ 91,014 $ 96,383 Aggregate depreciation expenses totaled $3,262 thousand and $2,409 thousand for the three months ended March 31, 2021 and 2020, respectively.

Intangible Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	6. Intangible Assets Intangible assets as of March 31, 2021 and December 31, 2020 are comprised of the following (in thousands): March 31, 2021 Gross Accumulated Net Intellectual property assets $ 9,288 $ (6,686 ) $ 2,602 Intangible assets $ 9,288 $ (6,686 ) $ 2,602 December 31, 2020 Gross Accumulated Net Intellectual property assets $ 9,486 $ (6,759 ) $ 2,727 Intangible assets $ 9,486 $ (6,759 ) $ 2,727 Aggregate amortization expenses for intangible assets totaled $186 thousand and $161 thousand for the three months ended March 31, 2021 and 2020, respectively.

Leases

Leases	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Leases	7. Leases The Company has operating and finance leases for buildings and other assets such as vehicles and office equipment. The Company’s leases have remaining lease terms ranging from 1 year to 5 years. The tables below present financial information related to the Company’s leases. Supplemental balance sheets information related to leases as of March 31, 2021 and December 31, 2020 are as follows (in thousands): Leases Classification March 31, December 31, Assets Operating lease Operating lease right-of-use assets $ 4,592 $ 4,632 Finance lease Property, plant and equipment, net 181 206 Total lease assets $ 4,773 $ 4,838 Liabilities Current Operating Operating lease liabilities $ 2,352 $ 2,210 Finance Other current liabilities 67 68 Non-current Operating Non-current 2,240 2,422 Finance Other non-current 130 153 Total lease liabilities $ 4,789 $ 4,853 The following table presents the weighted average remaining lease term and discount rate: March 31, December 31, Weighted average remaining lease term Operating leases 2.9 years 3.0 years Finance leases 2.8 years 3.0 years Weighted average discount rate Operating leases 5.15 % 5.55 % Finance leases 7.75 % 7.75 % The components of lease cost included in the Company’s consolidated statements of operations, are as follows (in thousands): Three Months March 31, March 31, Operating lease cost $ 680 $ 468 Finance lease cost Amortization of right-of-use 17 16 Interest on lease liabilities 4 5 Total lease cost $ 701 $ 489 The above table does not include an immaterial cost of short-term leases for the three months ended March 31, 2021 and 2020. Other lease information is as follows (in thousands): Three Months March 31, March 31, Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 680 $ 468 Operating cash flows from finance leases 4 5 Financing cash flows from finance leases 16 14 The aggregate future lease payments for operating and finance leases as of March 31, 2021 are as follows (in thousands): Operating Finance Remainder of 2021 $ 1,979 $ 60 2022 1,349 79 2023 663 79 2024 540 — 2025 407 — Total future lease payments 4,938 218 Less: Imputed interest (346 ) (21 ) Present value of future payments $ 4,592 $ 197

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2021
Payables and Accruals [Abstract]
Accrued Expenses	8. Accrued Expenses Accrued expenses as of March 31, 2021 a March 31, December 31, Payroll, benefits and related taxes, excluding severance benefits $ 9,380 $ 10,296 Withholding tax attributable to intercompany interest income 512 28 Interest on senior notes — 1,396 Outside service fees 1,461 755 Restructuring and others 5,925 2,658 Others 589 1,108 Accrued expenses $ 17,867 $ 16,241

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	9. Derivative Financial Instruments The Company’s Korean subsidiary from time to time has entered into zero cost collar 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 the zero cost collar contracts as of March 31, 2021 are as follows (in thousands): Date of transaction Total Month of settlement July 13, 2020 $ 15,000 April 2021 to June 2021 December 15, 2020 $ 30,000 July 2021 to December 2021 December 18, 2020 $ 9,000 April 2021 to June 2021 February 26, 2021 $ 18,000 July 2021 to December 2021 Details of the zero cost collar contracts as of December 31, 2020 are as follows (in thousands): Date of transaction Total Month of settlement July 13, 2020 $ 30,000 January 2021 to December 15, 2020 $ 30,000 July 2021 to December 2021 December 18, 2020 $ 18,000 March 2021 to June 2021 T he zero cost collar 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 fair values of the Company’s outstanding zero cost collar contracts recorded as assets and liabilities as of March 31, 2021 and December 31, 2020 are as follows (in thousands): Derivatives designated as hedging instruments: March 31, December 31, Asset Derivatives: Zero cost collars Other current assets $ 393 $ 2,036 Liability Derivatives: Zero cost collars Other current liabilities $ 1,243 $ 195 Offsetting of derivative assets and liabilities as of March 31, 2021 is as follows (in thousands): As of March 31, 2021 Gross amounts of Gross amounts Net amounts of Gross amounts not offset Net amount Financial Cash collateral Asset Derivatives: Zero cost collars $ 393 $ — $ 393 $ — $ — $ 393 Liability Derivatives: Zero cost collars $ 1,243 $ — $ 1,243 $ — $ — $ 1,243 Offsetting of derivative assets and liabilities as of December 31, 2020 is as follows (in thousands): As of December 31, 2020 Gross amounts of Gross amounts Net amounts of Gross amounts not offset Net amount Financial Cash collateral Asset Derivatives: Zero cost collars $ 2,036 $ — $ 2,036 $ — $ — $ 2,036 Liability Derivatives: Zero cost collars $ 195 $ — $ 195 $ — $ — $ 195 For derivative instruments that are designated and qualify as cash flow hedges, gains or losses on the derivative aside from components excluded from the assessment of effectiveness are 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 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 statements of operations for the three months ended March 31, 2021 and 2020. Net sales of discontinued operations for the three months ended March 31, 2020 are included in the below table (in thousands): Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Loss Location/Amount of Gain (Loss) Location/Amount of Gain (Loss) Three Months Ended Three Months Ended Three Months Ended 2021 2020 2021 2020 2021 2020 Zero cost collars $ (2,125 ) $ (5,004 ) Net sales $ 511 $ (58 ) Other income, net $ (86 ) $ 117 $ (2,125 ) $ (5,004 ) $ 511 $ (58 ) $ (86 ) $ 117 As of March 31, 2021, the amount expected to be reclassified from accumulated other comprehensive loss into loss within the next 12 The Company set aside cash deposits to the counterparties, Nomura Financial Investment (Korea) Co., Ltd. (“NFIK”), Deutsche Bank AG, Seoul Branch (“DB”) and Standard Chartered Bank Korea Limited (“SC”), as required for the zero cost collar contracts. These cash deposits are recorded as hedge collateral on the consolidated balance sheets. Cash deposits as of March 31, 2021 and December 31, 2020 are as follows (in thousands): Counterparties March 31, December 31, NFIK $ 3,250 $ 3,250 DB 1,000 1,000 SC 1,000 1,000 Total $ 5,250 $ 5,250 The Company is required to deposit additional cash collateral with NFIK and DB for any exposure in excess of $500 thousand, and no such cash collateral was required as of March 31, 2021 and December 31, 2020. These zero cost collar contracts may be terminated by the counterparties in a number of circumstances, including if the Company’s credit rating falls below B-/B3 than $ thousand at the end of a fiscal quarter, unless a waiver is obtained.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	10. Fair Value Measurements Fair Value of Financial Instruments As of March 31, 2021, the following table represents the Company’s assets and liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value Fair Value Quoted Prices in Significant Significant Assets: Derivative assets (other current assets) $ 393 $ 393 — $ 393 — Liabilities: Derivative liabilities (other current $ 1,243 $ 1,243 — $ 1,243 — As of December 31, 2020, the following table represents the Company’s assets and liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value Fair Value Quoted Prices in Significant Significant Assets: Derivative assets (other current assets) $ 2,036 $ 2,036 — $ 2,036 — Liabilities: Derivative liabilities (other current liabilities) $ 195 $ 195 — $ 195 — 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 Borrowings December 31, 2020 Carrying Fair (In thousands of U.S. Borrowings: 5.0% Exchangeable Senior Notes due March $ 83,479 $ 145,466 On January 17, 2017, the Company’s wholly owned subsidiary, MagnaChip Semiconductor S.A., closed an offering (the “Exchangeable Notes The Exchangeable Notes matured on March 1, 2021, unless they were earlier repurchased or converted. The Company estimated 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 11, “Borrowings.” Fair Values Measured on a Non-recurring The Company’s non-financial non-recurring

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Long-term Borrowings	11. Borrowings There were no borrowings outstanding as of March 31, 2021. As of December 31, 2020, the following table represents the Company’s borrowings (in thousands): December 31, 2020 5.0% Exchangeable Senior Notes due March 2021 $ 83,740 Less: unamortized discount and debt issuance costs (261 ) Total borrowings, net 83,479 Less: current portion of long-term borrowings, net 83,479 Long-term borrowings, net $ — 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 matured on March 1, 2021, unless they were earlier repurchased or converted. Holders had the right to 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 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 months ended March 31, 2021 and 2020 were $958 thousand and $1,416 thousand, respectively. In February 2019, the Company repurchased a principal amount equal to $920 thousand of the Exchangeable Notes in the open market, resulting in a loss of $63 thousand, which was recorded as loss on early extinguishment of borrowings, net in the consolidated statements of operations for the year ended December 31, 2019. In December 2018, the Company repurchased a principal amount equal to $1,590 thousand of the Exchangeable Notes in the open market, resulting in a loss of $234 thousand, which was recorded as loss on early extinguishment of borrowings, net in the consolidated statements of operations for the year ended December 31, 2018. Prior to the March 1, 2021 maturity of the Exchangeable Notes, holders elected to exchange all outstanding Exchangeable Notes for an aggregate of shares of the Company’s common stock in satisfaction in full of the outstanding obligations under the Exchangeable Notes. Upon conversion, the Company delivered for each $1,000 principal amount of converted Exchangeable Notes a number of shares equal to the exchange rate of 121.1387 shares of common stock per $1,000 principal amount of Exchangeable Notes, which was equivalent to an exchange price of approximately $8.26 per share of common stock. In connection with the exchanges, the fractional shares were paid in cash. Following March 1, 2021, the Company does not have any Exchangeable Notes outstanding.

Accrued Severance Benefits

Accrued Severance Benefits	3 Months Ended
	Mar. 31, 2021
Postemployment Benefits [Abstract]
Accrued Severance Benefits	12. 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 March 31, 2021, 98% of all employees of the Company were eligible for severance benefits. Changes in accrued severance benefits are as follows (in thousands): Three Months Ended March 31, March 31, Beginning balance $ 54,452 $ 53,344 Provisions 1,771 2,019 Severance payments (1,493 ) (1,952 ) Translation adjustments (2,177 ) (2,801 ) 52,553 50,610 Less: Cumulative contributions to severance insurance deposit accounts (13,212 ) (1,557 ) The National Pension Fund (61 ) (75 ) Group severance insurance plan (210 ) (213 ) Accrued severance benefits, net $ 39,070 $ 48,765 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 to certain severance insurance deposit accounts a certain percentage of severance benefits that are accrued for eligible employees for their services from January 1, 2018. 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 these 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 2021 $ 79 2022 261 2023 653 2024 935 2025 2,062 2026 2,364 2027 – 2031 19,921 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 Loss, Net

Foreign Currency Loss, Net	3 Months Ended
	Mar. 31, 2021
Foreign Currency [Abstract]
Foreign Currency Loss, Net	13. Foreign Currency Loss, Net Net foreign currency gain or loss includes non-cash non-cash

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	14 . Income Taxes The Company and its subsidiaries file income tax returns in Korea, Japan, Taiwan, the U.S. and in various other jurisdictions. The Company is subject to income or non-income The loss from continuing operations before income tax expense for the three months ended March 31, 2021 and 2020 w as For the three months ended March 31, 2021, the Company recorded an income tax expense of $290 thousand, primarily attributable to interest on intercompany loan balances, which was offset in part by the tax benefit recognized on the loss for the first quarter of 2021 from the Company’s Korean subsidiary. For the three months ended March 31, 2020, the Company recorded an income tax expense from the continuing operations of $1,303 thousand, primarily attributable to interest on intercompany loan balances. The income tax expense was recorded for the Company’s Korean subsidiary based on the estimated taxable income for the respective period, combined with its ability to utilize net operating loss carryforwards up to 60% in 2020.

Geographic and Other Informatio

Geographic and Other Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Geographic and Segment Information	15. Geographic and Other Information The following sets forth information relating to the single continuing operating segment (in thousands): Three Months Ended March 31, March 31, Revenues Standard products business Display Solutions $ 58,895 $ 77,593 Power Solutions 54,011 33,143 Total standard products business $ 112,906 $ 110,736 Transitional Fab 3 foundry services 10,113 9,737 Total revenues $ 123,019 $ 120,473 Three Months Ended March 31, March 31, Gross Profit Standard products business $ 33,659 $ 29,130 Transitional Fab 3 foundry services 723 — Total gross profit $ 34,382 $ 29,130 The following is a summary of net sales—standard products business (which does not include the Transitional Fab 3 Foundry Services) by geographic region, based on the location to which the products are billed (in thousands): Three Months Ended March 31, March 31, Korea $ 26,434 $ 30,817 Asia Pacific (other than Korea) 83,740 77,542 United States 1,274 709 Europe 1,243 971 Others 215 697 Total $ 112,906 $ 110,736 For the three months ended March 31, 2021 and 2020, of the Company’s net sales – standard products business in Asia Pacific (other than Korea), net sales – standard products business in China and Hong Kong represented % , Net sales from the Company’s top ten largest customers in the standard products business (which does not include the Transitional Fab 3 Foundry Services) accounted for 82% and 90% for the three months ended March 31, 2021 and 2020, respectively. For the three months ended March 31, 2021, the Company had two customers that represented 48.8% and 10.0% of its net sales – standard products business. For the three months ended March 31, 2020, the Company had two customers that represented 52.8% and 15.8% of its net sales – standard products business. As of March 31, 2021 and December 31, 2020, one customer accounted for 33.1% and 45.1% of accounts receivable, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	16. Accumulated Other Comprehensive Income (Loss) Accumulated other comprehensive income (loss) consists o March 31, December 31, Foreign currency translation adjustments $ 11 $ 2,069 Derivative adjustments (1,002 ) 1,634 Total $ (991 ) $ 3,703 Changes in accumulated other comprehensive income (loss) for the three months ended March 31, 2021 and 2020 are as follows (in thousands): Three Months Ended March 31, 2021 Foreign Derivative Total Beginning balance $ 2,069 $ 1,634 $ 3,703 Other comprehensive loss before reclassifications (2,058 ) (2,125 ) (4,183 ) Amounts reclassified from accumulated other comprehensive income — (511 ) (511 ) Net current-period other comprehensive loss (2,058 ) (2,636 ) (4,694 ) Ending balance $ 11 $ (1,002 ) $ (991 ) Three Months Ended March 31, 2020 Foreign Derivative Total Beginning balance $ (4,205 ) $ 1,545 $ (2,660 ) Other comprehensive income (loss) before reclassifications 22,251 (5,004 ) 17,247 Amounts reclassified from accumulated other comprehensive loss — 58 58 Net current-period other comprehensive income (loss) 22,251 (4,946 ) 17,305 Ending balance $ 18,046 $ (3,401 ) $ 14,645

Loss Per Share

Loss Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Loss Per Share	17. Loss Per Share The following table illustrates the computation of basic and diluted loss per common share for the three months ended March 31, 2021 and 2020: Three Months Ended March 31, March 31, (In thousands of US dollars, except share data) Basic and diluted loss per share Loss from continuing operations $ (7,473 ) $ (31,078 ) Income from discontinued operations, net of tax — 7,329 Net loss $ (7,473 ) $ (23,749 ) Weighted average number of shares – basic and diluted 40,292,838 34,893,157 Basic and diluted loss per common share Continuing operations $ (0.19 ) $ (0.89 ) Discontinued operations — 0.21 Total $ (0.19 ) $ (0.68 ) The following outstanding instruments were excluded from the computation of diluted loss per share, as they have an anti-dilutive effect on the calculation: Three Months Ended March 31, March 31, Options 1,471,421 2,163,845 Restricted Stock Units 1,109,572 729,939 For the three months ended March 31, 2021 and 2020, 5,783,919 shares and 10,144,155 shares, respectively, of potential common stock from the assumed conversion of Exchangeable Notes were also excluded from the computation of diluted loss per share as the effect were anti-dilutive for the period.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	18. Commitments and Contingencies Advances to Suppliers The Company, from time to time, may make advances in form of prepayments or deposits to suppliers to procure materials to meet its planned production. The Company recorded advances of $1,150 thousand and $5,500 thousand as other current assets as of March 31, 2021 and December 31, 2020, respectively. COVID-19 In December 2019, a strain of coronavirus causing a disease known as COVID-19 COVID-19 shelter-in-place COVID-19 re-imposition re-implemented COVID-19. The Company experienced some minor disruption in its Power Solutions business from assembly and test subcontractors located in China in the first quarter of 2020 as a result of the COVID-19 sub-contractors COVID-19 COVID-19 The Company continues to closely monitor and evaluate the nature and scope of the impact of the COVID-19 a Merger-related Complaints Since April 22, 2021, nine complaints have been filed seeking to enjoin the Merger, or, if the Merger is consummated, rescind the Merger or recover damages, as well as an award of each plaintiff’s fees and litigation expenses. The lawsuits, each filed as an individual action by a purported stockholder of the Company, are captioned as Schulthess v. Magnachip Semiconductor Corporation, et al. 1:21-cv-03587 Pittman v. Magnachip Semiconductor Corporation, et al. 1:21-cv-02306 Flanagan v. Magnachip Semiconductor Corporation, et al. 1:21-cv-03743 Castelli v. Magnachip Semiconductor Corporation, et al. 1:21-cv-03769 Doolittle v. Magnachip Semiconductor Corporation, et al. 1:21-cv-03801 Thomas v. Magnachip Semiconductor Corporation, et al. 1:21-cv-03860 Finger v. Magnachip Semiconductor Corporation, et al. 1:21-cv-03927 Kent v. Magnachip Semiconductor Corporation, et al Kennedy v. Magnachip Semiconductor Corporation, et al. 14a-9

Business, Basis of Presentati_2

Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
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 On September 1, 2020 (the “Closing Date”), the Company completed the sale of the Company’s Foundry Services Group business and its fabrication facility located in Cheongju, Korea, known as “Fab 4” to Key Foundry Co., Ltd. (the “Buyer”), a Korean corporation, in exchange for a purchase price equal to approximately $350.6 million in cash, pursuant to the terms of a business transfer agreement (the “Business Transfer Agreement”) dated March 31, 2020 by and among the Company and Magnus Semiconductor, LLC, a Korean limited liability company (“Magnus”). The purchase price was paid in a combination of U.S. Dollars in the amount of million. The Buyer is a wholly owned subsidiary of Magnus, which was established by Alchemist Capital Partners Korea Co., Ltd. and Credian Partners, Inc. On April 20, 2020, Magnus assigned, and the Buyer assumed, all rights and obligations of Magnus under the Business Transfer Agreement. This divestiture of the Foundry Services Group business and Fab 4 was made in connection with the Company’s strategic shift of its operational focus to its standard products business. The Foundry Services Group was historically a reportable segment. The Foundry Services Group business was classified as discontinued operations in the Company’s consolidated statements of operations and excluded from both continuing operations and segment results for the three months ended March 31, 2020. Accordingly, the Company has one reportable segment, its standard products business, together with transitional foundry services associated with its fabrication facility located in Gumi, Korea, known as “Fab 3,” that it expects to perform for the Buyer for a period of up to three years from the Closing Date (the “Transitional Fab 3 Foundry Services”). The Company’s standard products business includes its Display Solutions and Power Solutions business lines. The Company’s Display Solutions products provide panel display solutions to major suppliers of large and small rigid and flexible panel displays, and mobile, automotive applications and home appliances. The Company’s Power Solutions products include discrete and integrated circuit solutions for power management in communications, consumer and industrial applications .
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 (“U.S. 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 (“ASC”) 270, “Interim Reporting” and, accordingly, do not include all of the information and note disclosures required by U.S. GAAP for complete financial statements, except for the changes below. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for a full year or for any other periods. The consolidated statement of cash flow for the three months ended March 31, 2020 has not been adjusted to separately disclose the cash flow related to discontinued operations, but the material items in the operating and investing activities of the cash flow relating to discontinued operations for the same period is disclosed in Note 3. Unless otherwise stated, information in these notes to consolidated financial statements relates to the Company’s continuing operations and excludes the discontinued operations. The December 31, 2020 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by U.S. GAAP. The interim consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, 2019-12”). 2019-12 2019-12 2019-12

Discontinued Operations and A_2

Discontinued Operations and Assets Held for Sale (Tables)	3 Months Ended
	Mar. 31, 2021
Discontinued Operations and Assets Held for Sale [Abstract]
Schedule Of Results From Discontinued Operations	The following table summarizes the results from discontinued operations, net of tax, for the three months ended March 31, 2020. Three Months Ended March 31, (In thousands of US dollars) Revenues: Net sales – Foundry Services Group $ 86,279 Net sales – transitional Fab 3 foundry services (9,737 ) Total revenues 76,542 Cost of sales: Cost of sales – Foundry Services Group 65,583 Cost of sales – transitional Fab 3 foundry services (9,737 ) Total cost of sales 55,846 Gross profit 20,696 Operating expenses: Selling, general and administrative expenses 5,644 Research and development expenses 7,403 Restructuring and other charges 2,115 Total operating expenses 15,162 Operating income from discontinued operations 5,534 Foreign currency gain, net 2,097 Other income 107 Income from discontinued operations before income tax expense 7,738 Income tax expense 409 Income from discontinued operations, net of tax $ 7,329
Schedule Of Results From Discontinued Operations Alternative Cash Flow Information	The following table provides supplemental cash flows information related to discontinued operations: Three Months Ended March 31, (In thousands of US dollars) Significant non-cash Depreciation and amortization $ 5,365 Provision for severance benefits 3,052 Stock-based compensation 123 Investing activities: Capital expenditures $ (1,479 )

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories as of March 31, 2021 and December 31, 2020 consist of the following (in thousands): March 31, December 31, Finished goods $ 4,660 $ 6,425 Semi-finished goods and work-in-process 24,449 30,968 Raw materials 6,400 6,526 Materials in-transit 736 1,021 Less: inventory reserve (6,281 ) (5,901 ) Inventories, net $ 29,964 $ 39,039
Changes in Inventory Reserve	Changes in inventory reserve for the three months ended March 31, 2021 and 2020 are as follows (in thousands): Three Months Ended March 31, March 31, Beginning balance $ (5,901 ) $ (5,947 ) Change in reserve Inventory reserve charged to costs of sales (2,164 ) (1,275 ) Sale of previously reserved inventory 634 906 (1,530 ) (369 ) Write off 902 499 Translation adjustments 248 316 Reclassified to assets held for sale — 694 Ending balance $ (6,281 ) $ (4,807 )

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment	Property, plant and equipment a March 31, December 31, Buildings and related structures $ 24,110 $ 24,882 Machinery and equipment 102,365 106,244 Finance lease right-of-use 330 344 Others 39,600 40,116 166,405 171,586 Less: accumulated depreciation (89,948 ) (90,370 ) Land 14,557 15,167 Property, plant and equipment, net $ 91,014 $ 96,383

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	Intangible assets as of March 31, 2021 and December 31, 2020 are comprised of the following (in thousands): March 31, 2021 Gross Accumulated Net Intellectual property assets $ 9,288 $ (6,686 ) $ 2,602 Intangible assets $ 9,288 $ (6,686 ) $ 2,602 December 31, 2020 Gross Accumulated Net Intellectual property assets $ 9,486 $ (6,759 ) $ 2,727 Intangible assets $ 9,486 $ (6,759 ) $ 2,727

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Supplemental Balance Sheet Information Related To Leases [Table Text Block]	Supplemental balance sheets information related to leases as of March 31, 2021 and December 31, 2020 are as follows (in thousands): Leases Classification March 31, December 31, Assets Operating lease Operating lease right-of-use assets $ 4,592 $ 4,632 Finance lease Property, plant and equipment, net 181 206 Total lease assets $ 4,773 $ 4,838 Liabilities Current Operating Operating lease liabilities $ 2,352 $ 2,210 Finance Other current liabilities 67 68 Non-current Operating Non-current 2,240 2,422 Finance Other non-current 130 153 Total lease liabilities $ 4,789 $ 4,853
Lease, Cost [Table Text Block]	The following table presents the weighted average remaining lease term and discount rate: March 31, December 31, Weighted average remaining lease term Operating leases 2.9 years 3.0 years Finance leases 2.8 years 3.0 years Weighted average discount rate Operating leases 5.15 % 5.55 % Finance leases 7.75 % 7.75 %
Other Lease Information [Table Text Block]	The components of lease cost included in the Company’s consolidated statements of operations, are as follows (in thousands): Three Months March 31, March 31, Operating lease cost $ 680 $ 468 Finance lease cost Amortization of right-of-use 17 16 Interest on lease liabilities 4 5 Total lease cost $ 701 $ 489 Other lease information is as follows (in thousands): Three Months March 31, March 31, Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 680 $ 468 Operating cash flows from finance leases 4 5 Financing cash flows from finance leases 16 14
Schedule Of Future Lease Payments [Table Text Block]	The aggregate future lease payments for operating and finance leases as of March 31, 2021 are as follows (in thousands): Operating Finance Remainder of 2021 $ 1,979 $ 60 2022 1,349 79 2023 663 79 2024 540 — 2025 407 — Total future lease payments 4,938 218 Less: Imputed interest (346 ) (21 ) Present value of future payments $ 4,592 $ 197

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2021
Payables and Accruals [Abstract]
Summary of Accrued Expenses	Accrued expenses as of March 31, 2021 a March 31, December 31, Payroll, benefits and related taxes, excluding severance benefits $ 9,380 $ 10,296 Withholding tax attributable to intercompany interest income 512 28 Interest on senior notes — 1,396 Outside service fees 1,461 755 Restructuring and others 5,925 2,658 Others 589 1,108 Accrued expenses $ 17,867 $ 16,241

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Details of Derivative Contracts	Details of the zero cost collar contracts as of March 31, 2021 are as follows (in thousands): Date of transaction Total Month of settlement July 13, 2020 $ 15,000 April 2021 to June 2021 December 15, 2020 $ 30,000 July 2021 to December 2021 December 18, 2020 $ 9,000 April 2021 to June 2021 February 26, 2021 $ 18,000 July 2021 to December 2021 Details of the zero cost collar contracts as of December 31, 2020 are as follows (in thousands): Date of transaction Total Month of settlement July 13, 2020 $ 30,000 January 2021 to December 15, 2020 $ 30,000 July 2021 to December 2021 December 18, 2020 $ 18,000 March 2021 to June 2021 T he zero cost collar 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.
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 contracts recorded as assets and liabilities as of March 31, 2021 and December 31, 2020 are as follows (in thousands): Derivatives designated as hedging instruments: March 31, December 31, Asset Derivatives: Zero cost collars Other current assets $ 393 $ 2,036 Liability Derivatives: Zero cost collars Other current liabilities $ 1,243 $ 195
Offsetting of Derivative Assets and Liabilities	Offsetting of derivative assets and liabilities as of March 31, 2021 is as follows (in thousands): As of March 31, 2021 Gross amounts of Gross amounts Net amounts of Gross amounts not offset Net amount Financial Cash collateral Asset Derivatives: Zero cost collars $ 393 $ — $ 393 $ — $ — $ 393 Liability Derivatives: Zero cost collars $ 1,243 $ — $ 1,243 $ — $ — $ 1,243 Offsetting of derivative assets and liabilities as of December 31, 2020 is as follows (in thousands): As of December 31, 2020 Gross amounts of Gross amounts Net amounts of Gross amounts not offset Net amount Financial Cash collateral Asset Derivatives: Zero cost collars $ 2,036 $ — $ 2,036 $ — $ — $ 2,036 Liability Derivatives: Zero cost collars $ 195 $ — $ 195 $ — $ — $ 195
Impact of Derivative Instruments on Consolidated Statement of Operations	The following table summarizes the impact of derivative instruments on the consolidated statements of operations for the three months ended March 31, 2021 and 2020. Net sales of discontinued operations for the three months ended March 31, 2020 are included in the below table (in thousands): Derivatives in ASC 815 Cash Flow Hedging Relationships Amount of Loss Location/Amount of Gain (Loss) Location/Amount of Gain (Loss) Three Months Ended Three Months Ended Three Months Ended 2021 2020 2021 2020 2021 2020 Zero cost collars $ (2,125 ) $ (5,004 ) Net sales $ 511 $ (58 ) Other income, net $ (86 ) $ 117 $ (2,125 ) $ (5,004 ) $ 511 $ (58 ) $ (86 ) $ 117
Schedule Of Deposit Assets [Table Text Block]	These cash deposits are recorded as hedge collateral on the consolidated balance sheets. Cash deposits as of March 31, 2021 and December 31, 2020 are as follows (in thousands): Counterparties March 31, December 31, NFIK $ 3,250 $ 3,250 DB 1,000 1,000 SC 1,000 1,000 Total $ 5,250 $ 5,250

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	As of March 31, 2021, the following table represents the Company’s assets and liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value Fair Value Quoted Prices in Significant Significant Assets: Derivative assets (other current assets) $ 393 $ 393 — $ 393 — Liabilities: Derivative liabilities (other current $ 1,243 $ 1,243 — $ 1,243 — As of December 31, 2020, the following table represents the Company’s assets and liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands): Carrying Value Fair Value Quoted Prices in Significant Significant Assets: Derivative assets (other current assets) $ 2,036 $ 2,036 — $ 2,036 — Liabilities: Derivative liabilities (other current liabilities) $ 195 $ 195 — $ 195 —
Schedule of Fair Value of Long-term Borrowings	Fair Value of Borrowings December 31, 2020 Carrying Fair (In thousands of U.S. Borrowings: 5.0% Exchangeable Senior Notes due March $ 83,479 $ 145,466

Borrowings (Tables)

Borrowings (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Components of Long-term Borrowings	There were no borrowings outstanding as of March 31, 2021. As of December 31, 2020, the following table represents the Company’s borrowings (in thousands): December 31, 2020 5.0% Exchangeable Senior Notes due March 2021 $ 83,740 Less: unamortized discount and debt issuance costs (261 ) Total borrowings, net 83,479 Less: current portion of long-term borrowings, net 83,479 Long-term borrowings, net $ —

Accrued Severance Benefits (Tab

Accrued Severance Benefits (Tables)	3 Months Ended
	Mar. 31, 2021
Postemployment Benefits [Abstract]
Changes in Accrued Severance Benefits	Changes in accrued severance benefits are as follows (in thousands): Three Months Ended March 31, March 31, Beginning balance $ 54,452 $ 53,344 Provisions 1,771 2,019 Severance payments (1,493 ) (1,952 ) Translation adjustments (2,177 ) (2,801 ) 52,553 50,610 Less: Cumulative contributions to severance insurance deposit accounts (13,212 ) (1,557 ) The National Pension Fund (61 ) (75 ) Group severance insurance plan (210 ) (213 ) Accrued severance benefits, net $ 39,070 $ 48,765
Future Benefits Payments to Employees	The Company is liable to pay the following future benefits to its non-executive Severance benefit Remainder of 2021 $ 79 2022 261 2023 653 2024 935 2025 2,062 2026 2,364 2027 – 2031 19,921

Geographic and Other Informat_2

Geographic and Other Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of Operating Segments	The following sets forth information relating to the single continuing operating segment (in thousands): Three Months Ended March 31, March 31, Revenues Standard products business Display Solutions $ 58,895 $ 77,593 Power Solutions 54,011 33,143 Total standard products business $ 112,906 $ 110,736 Transitional Fab 3 foundry services 10,113 9,737 Total revenues $ 123,019 $ 120,473 Three Months Ended March 31, March 31, Gross Profit Standard products business $ 33,659 $ 29,130 Transitional Fab 3 foundry services 723 — Total gross profit $ 34,382 $ 29,130
Net Sales by Region, Based on Location of Products are Billed	The following is a summary of net sales—standard products business (which does not include the Transitional Fab 3 Foundry Services) by geographic region, based on the location to which the products are billed (in thousands): Three Months Ended March 31, March 31, Korea $ 26,434 $ 30,817 Asia Pacific (other than Korea) 83,740 77,542 United States 1,274 709 Europe 1,243 971 Others 215 697 Total $ 112,906 $ 110,736

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Loss	Accumulated other comprehensive income (loss) consists o March 31, December 31, Foreign currency translation adjustments $ 11 $ 2,069 Derivative adjustments (1,002 ) 1,634 Total $ (991 ) $ 3,703
Changes in Accumulated Other Comprehensive Loss	Changes in accumulated other comprehensive income (loss) for the three months ended March 31, 2021 and 2020 are as follows (in thousands): Three Months Ended March 31, 2021 Foreign Derivative Total Beginning balance $ 2,069 $ 1,634 $ 3,703 Other comprehensive loss before reclassifications (2,058 ) (2,125 ) (4,183 ) Amounts reclassified from accumulated other comprehensive income — (511 ) (511 ) Net current-period other comprehensive loss (2,058 ) (2,636 ) (4,694 ) Ending balance $ 11 $ (1,002 ) $ (991 ) Three Months Ended March 31, 2020 Foreign Derivative Total Beginning balance $ (4,205 ) $ 1,545 $ (2,660 ) Other comprehensive income (loss) before reclassifications 22,251 (5,004 ) 17,247 Amounts reclassified from accumulated other comprehensive loss — 58 58 Net current-period other comprehensive income (loss) 22,251 (4,946 ) 17,305 Ending balance $ 18,046 $ (3,401 ) $ 14,645

Loss Per Share (Tables)

Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Loss Per Common Share	The following table illustrates the computation of basic and diluted loss per common share for the three months ended March 31, 2021 and 2020: Three Months Ended March 31, March 31, (In thousands of US dollars, except share data) Basic and diluted loss per share Loss from continuing operations $ (7,473 ) $ (31,078 ) Income from discontinued operations, net of tax — 7,329 Net loss $ (7,473 ) $ (23,749 ) Weighted average number of shares – basic and diluted 40,292,838 34,893,157 Basic and diluted loss per common share Continuing operations $ (0.19 ) $ (0.89 ) Discontinued operations — 0.21 Total $ (0.19 ) $ (0.68 )
Schedule of Antidilutive Securities Excluded from the Computation of Loss Per Common Share	The following outstanding instruments were excluded from the computation of diluted loss per share, as they have an anti-dilutive effect on the calculation: Three Months Ended March 31, March 31, Options 1,471,421 2,163,845 Restricted Stock Units 1,109,572 729,939

Business, Basis of Presentati_3

Business, Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - Sep. 01, 2020 $ in Millions, ₩ in Billions	USD ($)	KRW (₩)
Foundry Services Group [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Proceeds from Sale of Business	$ 350.6
MX Foundry Services Group [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses	46.5	₩ 360.6
Liabilities Incurred	$ 100

Merger Agreement - Additional I

Merger Agreement - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 25, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Business acquisition, share price	$ 0.01		$ 0.01
South Dearborn Limited [Member]
Business Acquisition [Line Items]
Business acquisition, share price		$ 0.01
Business acquisition, consideration in cash	$ 29
Business acquisition, transaction costs	$ 9,831

Discontinued Operations and A_3

Discontinued Operations and Assets Held for Sale - Schedule Of Results From Discontinued Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Expenses [Abstract]
Income from discontinued operations, net of tax	$ 0	$ 7,329
Discontinued Operations [Member]
Revenues:
Total revenues		76,542
Cost of sales:
Total cost of sales		55,846
Gross profit		20,696
Operating Expenses [Abstract]
Selling, general and administrative expenses		5,644
Research and development expenses		7,403
Restructuring and other charges		2,115
Total operating expenses		15,162
Operating income from discontinued operations		5,534
Foreign currency gain, net		2,097
Other income		107
Income from discontinued operations before income tax expense		7,738
Income tax expense		409
Income from discontinued operations, net of tax		7,329
Foundry Services Group [Member] | Discontinued Operations [Member]
Revenues:
Total revenues		86,279
Cost of sales:
Total cost of sales		65,583
Fab Three Foundry Services [Member] | Discontinued Operations [Member]
Revenues:
Total revenues		(9,737)
Cost of sales:
Total cost of sales		$ (9,737)

Discontinued Operations and A_4

Discontinued Operations and Assets Held for Sale - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
MX Foundry Services Group [Member]
Schedule Of Disposal Group Not Discontinued Operation Income Statement [Line Items]
Gain on sale of foundry services group business			$ 287,117
Foundry Services Group And Fab Four [Member]
Schedule Of Disposal Group Not Discontinued Operation Income Statement [Line Items]
Restructuring and other charges		$ 2,115
Foundry Services Group And Fab Four [Member] | MX Foundry Services Group [Member]
Schedule Of Disposal Group Not Discontinued Operation Income Statement [Line Items]
Accounts receivable from transaction services agreement	$ 13,624

Discontinued Operations and A_5

Discontinued Operations and Assets Held for Sale - Schedule Of Results From Discontinued Operations Alternative Cash Flow Information (Detail) - Foundry Services Group And Fab Three Foundry Services [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Significant non-cash operating activities:
Depreciation and amortization	$ 5,365
Provision for severance benefits	3,052
Stock-based compensation	123
Investing activities:
Capital expenditures	$ (1,479)

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Finished goods	$ 4,660	$ 6,425
Semi-finished goods and work-in-process	24,449	30,968
Raw materials	6,400	6,526
Materials in-transit	736	1,021
Less: inventory reserve	(6,281)	(5,901)	$ (4,807)	$ (5,947)
Inventories, net	$ 29,964	$ 39,039

Inventories - Changes in Invent

Inventories - Changes in Inventory Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Inventory Disclosure [Abstract]
Beginning balance	$ (5,901)	$ (5,947)
Change in reserve
Inventory reserve charged to costs of sales	(2,164)	(1,275)
Sale of previously reserved inventory	634	906
Change in reserve	(1,530)	(369)
Write off	902	499
Translation adjustments	248	316
Reclassified to assets held for sale		694
Ending balance	$ (6,281)	$ (4,807)

Property, Plant and Equipment -

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Depreciation expenses	$ 3,262	$ 2,409

Property, Plant and Equipment_2

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 166,405	$ 171,586
Less: accumulated depreciation	(89,948)	(90,370)
Property, plant and equipment, net	91,014	96,383
Buildings and Related Structures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	24,110	24,882
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	102,365	106,244
Finance Lease Right Of Use Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	330	344
Others [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	39,600	40,116
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 14,557	$ 15,167

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense for intangible assets	$ 186	$ 161

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	$ 9,288	$ 9,486
Accumulated amortization	(6,686)	(6,759)
Intangible asset, Net amount	2,602	2,727
Intellectual Property Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	9,288	9,486
Accumulated amortization	(6,686)	(6,759)
Intangible asset, Net amount	$ 2,602	$ 2,727

Leases - Additional Information

Leases - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021
Maximum [Member]
Lease Agreements Remaining Term of Lease	5 years
Minimum [Member]
Lease Agreements Remaining Term of Lease	1 year

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets
Operating lease	$ 4,592	$ 4,632
Total lease assets	4,773	4,838
Current
Operating	2,352	2,210
Non-current
Operating	2,240	2,422
Total lease liabilities	4,789	4,853
Operating Lease Right Of Use Assets [Member]
Assets
Operating lease	4,592	4,632
Property, Plant and Equipment, Net [Member]
Assets
Finance lease	181	206
Current Operating Lease Liabilities [Member]
Current
Operating	2,352	2,210
Other Current Liabilities [Member]
Current
Finance	67	68
Non Current Operating Lease Liabilities [Member]
Non-current
Operating	2,240	2,422
Other Noncurrent Liabilities [Member]
Non-current
Finance	$ 130	$ 153

Leases - Components of lease co

Leases - Components of lease cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 680	$ 468
Finance lease cost [Abstract]
Amortization of right-of-use assets	17	16
Interest on lease liabilities	4	5
Total lease cost	$ 701	$ 489

Leases - Other lease informatio

Leases - Other lease information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 680	$ 468
Operating cash flows from finance leases	4	5
Financing cash flows from finance leases	$ 16	$ 14
Weighted average remaining lease term
Operating leases	2 years 10 months 24 days		3 years
Finance leases	2 years 9 months 18 days		3 years
Weighted average discount rate
Operating leases	5.15%		5.55%
Finance leases	7.75%		7.75%

Leases - Aggregate future lease

Leases - Aggregate future lease payment (Detail) $ in Thousands	Mar. 31, 2021USD ($)
Leases [Abstract]
Operating Leases, Remainder of 2021	$ 1,979
Operating Leases, 2022	1,349
Operating Leases, 2023	663
Operating Leases, 2024	540
Operating Leases, 2025	407
Operating Leases, Total future lease payments	4,938
Less: Present value adjustment	(346)
Present value of future payments	4,592
Finance Leases [Abstract]
Finance Leases, Remainder of 2021	60
Finance Leases, 2022	79
Finance Leases, 2023	79
Finance Leases, 2024	0
Finance Leases, 2025	0
Finance Leases, Total future lease payments	218
Less: Present value adjustment	(21)
Present value of future payments	$ 197

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Payroll, benefits and related taxes, excluding severance benefits	$ 9,380	$ 10,296
Withholding tax attributable to intercompany interest income	512	28
Interest on senior notes		1,396
Outside service fees	1,461	755
Restructuring and others	5,925	2,658
Others	589	1,108
Accrued expenses	$ 17,867	$ 16,241

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Estimated amount reclassified from accumulated other comprehensive income into income	$ 1,002
Zero Cost Collar and Forward Contracts [Member] | Nomura Financial Investment (Korea) Co., Ltd. [Member]
Derivative [Line Items]
Threshold amount of cash collateral	500	$ 0
Termination provisions for cash and cash equivalents	$ 30,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Details of Derivative Contracts (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Zero Cost Collar One [Member]
Derivative [Line Items]
Date of transaction	Jul. 13, 2020	Jul. 13, 2020
Total notional amount	$ 15,000	$ 30,000
Month of settlement, start	2021-04	2021-01
Month of settlement, end	2021-06	2021-06
Zero Cost Collar Two [Member]
Derivative [Line Items]
Date of transaction	Dec. 15, 2020	Dec. 15, 2020
Total notional amount	$ 30,000	$ 30,000
Month of settlement, start	2021-07	2021-07
Month of settlement, end	2021-12	2021-12
Zero Cost Collar Three [Member]
Derivative [Line Items]
Date of transaction	Dec. 18, 2020	Dec. 18, 2020
Total notional amount	$ 9,000	$ 18,000
Month of settlement, start	2021-04	2021-03
Month of settlement, end	2021-06	2021-06
Zero Cost Collar Four [Member]
Derivative [Line Items]
Date of transaction	Feb. 26, 2021
Total notional amount	$ 18,000
Month of settlement, start	2021-07
Month of settlement, end	2021-12

Derivative Financial Instrume_5

Derivative Financial Instruments - Fair Values of Outstanding Zero Cost Collar and Forward Contracts Recorded as Assets and Liabilities (Detail) - Zero Cost Collars [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Asset Derivatives:
Other current assets	$ 393	$ 2,036
Liability Derivatives:
Other current liabilities	1,243	195
Other Current Assets [Member]
Asset Derivatives:
Other current assets	393	2,036
Other Current Liabilities [Member]
Liability Derivatives:
Other current liabilities	$ 1,243	$ 195

Derivative Financial Instrume_6

Derivative Financial Instruments - Offsetting of Derivative Assets and Liabilities (Details) - Zero Cost Collars [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Asset Derivatives:
Asset Derivatives, Gross amounts of recognized assets/liabilities	$ 393	$ 2,036
Asset Derivatives, Gross amounts offset in the balance sheets	0	0
Asset Derivatives, Net amounts of assets/liabilities presented in the balance sheets	393	2,036
Asset Derivatives, Gross amounts not offset in the balance sheets, Financial instruments	0	0
Asset Derivatives, Gross amounts not offset in the balance sheets, Cash collateral pledged	0	0
Asset Derivatives, Net amount	393	2,036
Liability Derivatives:
Liability Derivatives, Gross amounts of recognized liabilities	1,243	195
Liability Derivatives, Gross amounts offset in the balance sheets	0	0
Liability Derivatives, Net amounts of liabilities presented in the balance sheets	1,243	195
Liability Derivatives, Gross amounts not offset in the balance sheets, Financial instruments	0	0
Liability Derivatives, Gross amounts not offset in the balance sheets, Cash collateral pledged	0	0
Liability Derivatives, Net amount after master netting	$ 1,243	$ 195

Derivative Financial Instrume_7

Derivative Financial Instruments - Impact of Derivative Instruments on Consolidated Statement of Operations (Detail) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Amount of Loss Recognized in AOCI on Derivatives (Effective Portion)	$ (2,125)	$ (5,004)
Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	511	(58)
Amount of Loss Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(86)	117
Zero Cost Collars [Member]
Derivative [Line Items]
Amount of Loss Recognized in AOCI on Derivatives (Effective Portion)	(2,125)	(5,004)
Zero Cost Collars [Member] | Other income, net [Member]
Derivative [Line Items]
Amount of Loss Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(86)	117
Zero Cost Collars [Member] | Net Sales [Member]
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	$ 511	$ (58)

Derivative Financial Instrume_8

Derivative Financial Instruments - Cash deposits (Details) - Zero Cost Collar And Forward Contracts [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deposit Assets [Line Items]
Margin Deposit Assets	$ 5,250	$ 5,250
DB
Deposit Assets [Line Items]
Margin Deposit Assets	1,000	1,000
NFIK
Deposit Assets [Line Items]
Margin Deposit Assets	3,250	3,250
SC
Deposit Assets [Line Items]
Margin Deposit Assets	$ 1,000	$ 1,000

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 17, 2017	Mar. 31, 2021	Dec. 31, 2020	Feb. 28, 2019	Dec. 31, 2018
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
Debt issuance costs paid	$ 5,902	$ 5,902
Principal Repurchase Amount Of Exchangeable Notes				$ 920	$ 1,590
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

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Carrying Value [Member] | Other Current Assets [Member]
Assets:
Derivative assets	$ 393	$ 2,036
Carrying Value [Member] | Other Current Liabilities [Member]
Liabilities:
Derivative liabilities	1,243	195
Estimate of Fair Value Measurement [Member] | Other Current Assets [Member]
Assets:
Derivative assets	393	2,036
Estimate of Fair Value Measurement [Member] | Other Current Liabilities [Member]
Liabilities:
Derivative liabilities	1,243	195
Significant Other Observable Inputs (Level 2) [Member] | Other Current Assets [Member]
Assets:
Derivative assets	393	2,036
Significant Other Observable Inputs (Level 2) [Member] | Other Current Liabilities [Member]
Liabilities:
Derivative liabilities	$ 1,243	$ 195

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Long-term Borrowings:
Carrying amount of senior notes		$ 0
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	$ 83,479
Estimated fair value of senior notes		$ 145,466

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Fair Value of Long-term Borrowings (Parenthetical) (Detail) - 5.0% Exchangeable Senior Notes due March 2021 [Member] - Exchangeable Senior Notes [Member]	Jan. 17, 2017	Mar. 31, 2021	Dec. 31, 2020
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

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - 5.0% Exchangeable Senior Notes due March 2021 [Member] - Exchangeable Senior Notes [Member] - USD ($) $ in Thousands	Mar. 01, 2021	Jan. 17, 2017	Jan. 17, 2017	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Feb. 28, 2019
Debt Instrument [Line Items]
Aggregate principal amount		$ 86,250	$ 86,250
Interest rate		5.00%	5.00%	5.00%				5.00%
Aggregate principal amount of senior notes pricing			5.00%
Conversion of converted notes, shares issued	10,144,131
Debt issuance costs paid		$ 5,902		$ 5,902
Interest expense related to the Exchangeable Notes				$ 958	$ 1,416
Debt Instrument, Repurchased Face Amount							$ 1,590		$ 920
Loss on early extinguishment of long-term borrowings, net						$ 63	$ 234

Borrowings - Components of Long

Borrowings - Components of Long-term Borrowings (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Less: unamortized discount and debt issuance costs	$ (261)
Total borrowings, net	83,479
Less: current portion of long-term borrowings, net	83,479
Long-term borrowings, net	0
Exchangeable Senior Notes [Member] | 5.0% Exchangeable Senior Notes due March 2021 [Member]
Debt Instrument [Line Items]
Long-term borrowings	$ 83,740

Accrued Severance Benefits - Ad

Accrued Severance Benefits - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021
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
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Postemployment Benefits [Abstract]
Beginning balance	$ 54,452	$ 53,344
Provisions	1,771	2,019
Severance payments	(1,493)	(1,952)
Translation adjustments	(2,177)	(2,801)
Ending balance	52,553	50,610
Less: Cumulative contributions to severance insurance deposit accounts	(13,212)	(1,557)
The National Pension Fund	(61)	(75)
Group severance insurance plan	(210)	(213)
Accrued severance benefits, net	$ 39,070	$ 48,765	$ 40,462

Accrued Severance Benefits - Fu

Accrued Severance Benefits - Future Benefits Payments to Employees (Detail) $ in Thousands	Mar. 31, 2021USD ($)
Retirement Benefits [Abstract]
Remainder of 2021	$ 79
2022	261
2023	653
2024	935
2025	2,062
2026	2,364
2027 – 2030	$ 19,921

Foreign Currency Loss, Net - Ad

Foreign Currency Loss, Net - Additional Information (Detail) $ in Thousands	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Foreign Currency Transaction [Abstract]
Exchange rates using first base rate	1,133.5	1,088
Intercompany loan balances	$ 381,800	$ 378,852

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Tax Contingency [Line Items]
Income tax expenses (benefits)	$ 290	$ 1,303
Loss from continuing operations before income tax expense	$ (7,183)	$ (29,775)
Korean Subsidiary [Member]
Income Tax Contingency [Line Items]
The net operating income carry forwards of the taxable income			60.00%

Geographic and Other Informat_3

Geographic and Other Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Customer Concentration Risk [Member] | Net Sales [Member] | Top Ten Customers [Member] | Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	82.00%	90.00%
Customer Concentration Risk [Member] | Net Sales [Member] | Top Customer One [Member] | Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	48.80%	52.80%
Customer Concentration Risk [Member] | Net Sales [Member] | Top Customer Two [Member] | Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	10.00%	15.80%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Top Customer One [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	33.10%	45.10%
Geographic Concentration Risk [Member] | Net Sales [Member] | Asia Pacific Other Than Korea [Member] | Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	57.10%
Geographic Concentration Risk [Member] | Net Sales [Member] | CHINA, HONG KONG | Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage		95.30%
Geographic Concentration Risk [Member] | Net Sales [Member] | VIET NAM | Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	37.40%	1.00%

Geographic and Other Informat_4

Geographic and Other Information - Schedule of Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 123,019	$ 120,473
Total gross profit	34,382	29,130
Standard products business [Member]
Segment Reporting Information [Line Items]
Total revenues	112,906	110,736
Total gross profit	33,659	29,130
Fab Three Foundry Services [Member]
Segment Reporting Information [Line Items]
Total revenues	10,113	9,737
Total gross profit	723
Operating Segments [Member] | Standard products business [Member]
Segment Reporting Information [Line Items]
Total revenues	112,906	110,736
Operating Segments [Member] | Standard products business [Member] | Display Solutions [Member]
Segment Reporting Information [Line Items]
Total revenues	58,895	77,593
Operating Segments [Member] | Standard products business [Member] | Power Solutions [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 54,011	$ 33,143

Geographic and Other Informat_5

Geographic and Other Information - Net Sales by Region, Based on Location of Products are Billed (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 123,019	$ 120,473
Standard products business [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	112,906	110,736
Standard products business [Member] | Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	26,434	30,817
Standard products business [Member] | Asia Pacific (Other Than Korea) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	83,740	77,542
Standard products business [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	1,274	709
Standard products business [Member] | Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	1,243	971
Standard products business [Member] | Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 215	$ 697

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Foreign currency translation adjustments	$ 11	$ 2,069
Derivative adjustments	(1,002)	1,634
Total	$ (991)	$ 3,703

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	$ 345,600	$ (14,981)
Total other comprehensive income (loss)	(4,694)	17,305
Balance ending	420,347	(21,156)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	2,069	(4,205)
Other comprehensive income (loss) before reclassifications	(2,058)	22,251
Total other comprehensive income (loss)	(2,058)	22,251
Balance ending	11	18,046
Derivative Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	1,634	1,545
Other comprehensive income (loss) before reclassifications	(2,125)	(5,004)
Amounts reclassified from accumulated other comprehensive loss	(511)	58
Total other comprehensive income (loss)	(2,636)	(4,946)
Balance ending	(1,002)	(3,401)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	3,703	(2,660)
Other comprehensive income (loss) before reclassifications	(4,183)	17,247
Amounts reclassified from accumulated other comprehensive loss	(511)	58
Total other comprehensive income (loss)	(4,694)	17,305
Balance ending	$ (991)	$ 14,645

Loss Per Share - Additional Inf

Loss Per Share - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Conversion Of Exchangeable Notes	5,783,919	10,144,155

Loss Per Share - Schedule of Co

Loss Per Share - Schedule of Computation of Basic and Diluted Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic and diluted loss per common share—
Loss from continuing operations	$ (7,473)	$ (31,078)
Income from discontinued operations, net of tax	0	7,329
Net loss	$ (7,473)	$ (23,749)
Weighted average number of shares – basic and diluted	40,292,838	34,893,157
Basic and diluted loss per common share
Continuing operations	$ (0.19)	$ (0.89)
Discontinued operations	0	0.21
Total	$ (0.19)	$ (0.68)

Loss Per Share - Schedule of An

Loss Per Share - Schedule of Antidilutive Securities Excluded from the Computation of Loss Per Common Share (Detail) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding units and warrants excluded from computation of diluted loss per share/unit	5,783,919	10,144,155
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	1,471,421	2,163,845
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	1,109,572	729,939

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Current Assets [Member]
Loss Contingencies [Line Items]
Prepayments to suppliers	$ 1,150	$ 5,500