0001193125-21-156213 | 10-Q | XBRL Viewer | Magnachip Semiconductor Corp

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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

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

f the following as of March 31, 2021 and December 31, 2020, respectively (in thousands):


	March 31, 2021			December 31, 2020
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 currency translation adjustments			Derivative adjustments			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 currency translation adjustments			Derivative adjustments			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

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

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

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

Income Taxes	3 Months Ended
Income Taxes	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 tax examinations by tax authorities of these jurisdictions for all open tax years. The loss from continuing operations before income tax expense for the three months ended March 31, 2021 and 2020 w as $7,183 thousand and $29,775 thousand, respectively. 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.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

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%

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, 2021		March 31, 2020
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, 2021		March 31, 2020
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, 2021		March 31, 2020
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

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 March 31, 2021		Fair Value Measurement March 31, 2021		Quoted Prices in Active Markets for Identical Asset / Liability (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Derivative assets (other current assets)	$	393	$	393		—	$	393		—
Liabilities:
Derivative liabilities (other current liabilities)	$	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 December 31, 2020		Fair Value Measurement December 31, 2020		Quoted Prices in Active Markets for Identical Asset / Liability (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
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 Value		Fair Value
	(In thousands of U.S. dollars)
Borrowings:
5.0% Exchangeable Senior Notes due March 2021 (Level 2)	$	83,479	$	145,466

On January 17, 2017, the Company’s wholly owned subsidiary, MagnaChip Semiconductor S.A., closed an offering (the “Exchangeable Notes

Offering”) of 5.0% Exchangeable Senior Notes due March 1, 2021 (the “Exchangeable Notes”), of $86,250 thousand, which represents the principal amount, excluding $5,902 thousand of debt issuance costs. In December 2018 and February 2019, MagnaChip Semiconductor S.A. repurchased a principal amount equal to $1,590 thousand and $920 thousand, respectively, of the Exchangeable Notes in the open market.

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

Basis

The Company’s

non-financial

assets, such as property, plant and equipment, and intangible assets are recorded at fair value upon acquisition and are remeasured at fair value only if an impairment charge is recognized. As of March 31, 2021 and 2020 the Company did not have any assets or liabilities measured at fair value on a

non-recurring

basis.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

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	$	—

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
-Paragraph 1
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 505
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-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

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, 2021		December 31, 2020
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 operating lease liabilities		2,240		2,422
Finance	Other non-current liabilities		130		153

Total lease liabilities		$	4,789	$	4,853

The following table presents the weighted average remaining lease term and discount rate:


	March 31, 2021			December 31, 2020
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 Ended
	March 31, 2021		March 31, 2020
Operating lease cost	$	680	$	468
Finance lease cost
Amortization of right-of-use assets		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 Ended
	March 31, 2021		March 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

The aggregate future lease payments for operating and finance leases as of March 31, 2021 are as follows (in thousands):


	Operating Leases			Finance Leases
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

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]		3 Months Ended	12 Months Ended
	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. 01, 2021	Mar. 01, 2021	Mar. 01, 2021

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

s of March 31, 2021 and December 31, 2020 are comprised of the following (in thousands):


	March 31, 2021			December 31, 2020
Buildings and related structures	$	24,110		$	24,882
Machinery and equipment		102,365			106,244
Finance lease right-of-use assets		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

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)

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, 2021			December 31, 2020
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, 2021			March 31, 2020
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

and raw materials. Write off of this reserve is recognized only when the related inventory has been disposed or scrapped.

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, 2021		December 31, 2020
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 operating lease liabilities		2,240		2,422
Finance	Other non-current liabilities		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, 2021			December 31, 2020
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 Ended
	March 31, 2021		March 31, 2020
Operating lease cost	$	680	$	468
Finance lease cost
Amortization of right-of-use assets		17		16
Interest on lease liabilities		4		5

Total lease cost	$	701	$	489

Other lease information is as follows (in thousands):


	Three Months Ended
	March 31, 2021		March 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

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 Leases			Finance Leases
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

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 March 31, 2021		Fair Value Measurement March 31, 2021		Quoted Prices in Active Markets for Identical Asset / Liability (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Derivative assets (other current assets)	$	393	$	393		—	$	393		—
Liabilities:
Derivative liabilities (other current liabilities)	$	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 December 31, 2020		Fair Value Measurement December 31, 2020		Quoted Prices in Active Markets for Identical Asset / Liability (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
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 Value		Fair Value
	(In thousands of U.S. dollars)
Borrowings:
5.0% Exchangeable Senior Notes due March 2021 (Level 2)	$	83,479	$	145,466

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

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, 2020
	(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, 2020
	(In thousands of US dollars)
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	)

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

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

$13,624 thousand for the three months ended March 31, 2021.

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, 2020
	(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, 2020
	(In thousands of US dollars)
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	)

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%

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

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, 2021		March 31, 2020
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, 2021		March 31, 2020
Gross Profit
Standard products business	$	33,659	$	29,130
Transitional Fab 3 foundry services		723		—

Total gross profit	$	34,382	$	29,130


	Three Months Ended
	March 31, 2021		March 31, 2020
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

57.1% and 95.3

respectively, and net sales—standard products business in Vietnam represented 37.4% and 1.0%, respectively.

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.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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

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

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

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

f the following as of March 31, 2021 and December 31, 2020, respectively (in thousands):


	March 31, 2021			December 31, 2020
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 currency translation adjustments			Derivative adjustments			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 currency translation adjustments			Derivative adjustments			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

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

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, 2021			March 31, 2020
	(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, 2021		March 31, 2020
Options		1,471,421		2,163,845
Restricted Stock Units		1,109,572		729,939

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 notional amount		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 notional amount		Month of settlement
July 13, 2020	$	30,000	January 2021 to June 2021
December 15, 2020	$	30,000	July 2021 to December 2021
December 18, 2020	$	18,000	March 2021 to June 2021

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, 2021		December 31, 2020
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 recognized assets/liabilities		Gross amounts offset in the balance sheets		Net amounts of assets/liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets				Net amount
As of March 31, 2021	Gross amounts of recognized assets/liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged		Net amount
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 recognized assets/liabilities		Gross amounts offset in the balance sheets		Net amounts of assets/liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets				Net amount
As of December 31, 2020	Gross amounts of recognized assets/liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged		Net amount
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 Recognized in AOCI on Derivatives						Location/Amount of Gain (Loss) Reclassified from AOCI Into Statement of Operations							Location/Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives
	Three Months Ended March 31,								Three Months Ended March 31,							Three Months Ended March 31,
	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, 2021		December 31, 2020
NFIK	$	3,250	$	3,250
DB		1,000		1,000
SC		1,000		1,000

Total	$	5,250	$	5,250

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

+ References

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+ Details

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 - Aggregate future lease payment (Detail) $ in Thousands	Mar. 31, 2021 USD ($)
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

Foreign Currency Loss, Net	3 Months Ended
Foreign Currency Loss, Net	Mar. 31, 2021
Foreign Currency [Abstract]
Foreign Currency Loss, Net	13. Foreign Currency Loss, Net Net foreign currency gain or loss includes non-cash translation gain or loss associated with intercompany balances. A substantial portion of the Company’s net foreign currency gain or loss is non-cash translation gain or loss associated with intercompany long-term loans to the Company’s Korean subsidiary. The loans are denominated in U.S. dollars and are affected by changes in the exchange rate between the Korean won and the U.S. dollar. As of March 31, 2021 and December 31, 2020, the outstanding intercompany loan balances including accrued interest between the Korean subsidiary and the Dutch subsidiary were $381,800 thousand and $378,852 thousand, respectively. The Korean won to U.S. dollar exchange rates were 1,133.5:1 and 1,088.0:1 using the first base rate as of March 31, 2021 and December 31, 2020, respectively, as quoted by the KEB Hana Bank.

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)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

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)

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

Cover Page - shares	3 Months Ended
Cover Page - shares	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

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

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 amount		Accumulated amortization			Net amount
Intellectual property assets	$	9,288	$	(6,686	)	$	2,602

Intangible assets	$	9,288	$	(6,686	)	$	2,602


	December 31, 2020
	Gross amount		Accumulated amortization			Net amount
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.

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

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

+ References + Details

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 amount		Accumulated amortization			Net amount
Intellectual property assets	$	9,288	$	(6,686	)	$	2,602

Intangible assets	$	9,288	$	(6,686	)	$	2,602


	December 31, 2020
	Gross amount		Accumulated amortization			Net amount
Intellectual property assets	$	9,486	$	(6,759	)	$	2,727

Intangible assets	$	9,486	$	(6,759	)	$	2,727

Borrowings - Additional Information (Detail) - 5.0% Exchangeable Senior Notes due March 2021 [Member] - Exchangeable Senior Notes [Member] - USD ($) $ in Thousands				3 Months Ended		12 Months Ended
	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

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

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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+ Details

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

- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
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-Subparagraph (b)
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
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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 notional amount		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 notional amount		Month of settlement
July 13, 2020	$	30,000	January 2021 to June 2021
December 15, 2020	$	30,000	July 2021 to December 2021
December 18, 2020	$	18,000	March 2021 to June 2021

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, 2021		December 31, 2020
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 recognized assets/liabilities		Gross amounts offset in the balance sheets		Net amounts of assets/liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets				Net amount
As of March 31, 2021	Gross amounts of recognized assets/liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged		Net amount
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 recognized assets/liabilities		Gross amounts offset in the balance sheets		Net amounts of assets/liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets				Net amount
As of December 31, 2020	Gross amounts of recognized assets/liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged		Net amount
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.


Derivatives in ASC 815 Cash Flow Hedging Relationships	Amount of Loss Recognized in AOCI on Derivatives						Location/Amount of Gain (Loss) Reclassified from AOCI Into Statement of Operations							Location/Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives
	Three Months Ended March 31,								Three Months Ended March 31,							Three Months Ended March 31,
	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

months is $1,002 thousand.

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, 2021		December 31, 2020
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

or if the Company’s total cash and cash equivalents is less

than $

30,000

thousand at the end of a fiscal quarter, unless a waiver is obtained.

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

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)

- Definition

Amount after tax of income (loss) from continuing operations including portion attributable to the noncontrolling interest.

+ References

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+ Details

- Definition

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(12))
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-URI http://asc.fasb.org/extlink&oid=109227538&loc=d3e44648-109337

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

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)

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 memory and Radio Frequency (“RF”) applications. 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 $46.5 million and Korean Won in the amount of approximately KRW 360.6 billion. In addition to the purchase price, the Buyer assumed all severance liabilities relating to the transferred employees, which had a value of approximately $100 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 for the fiscal year ended December 31, 2020.
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, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes” (“ASU 2019-12”). ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The Company adopted ASU 2019-12 as of January 1, 2021, and the adoption of ASU 2019-12 did not have a material impact on the Company’s consolidated financial statements.

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%

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, 2021			March 31, 2020
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

employees upon their normal retirement age (in thousands):


	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

employees’ current salary rates and the number of service years that will be accumulated upon their retirement dates. These amounts do not include amounts that might be paid to

non-executive

employees that will cease working with the Company before their normal retirement ages.

Korea’s mandatory retirement age is 60 under the Employment Promotion for the Aged Act.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	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 Pandemic In December 2019, a strain of coronavirus causing a disease known as COVID-19 surfaced in Wuhan, China, resulting in significant disruptions among Chinese manufacturing and other facilities and travel throughout China. In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. Governmental authorities throughout the world have implemented numerous containment measures, including travel bans and restrictions, quarantines, shelter-in-place orders, and business restrictions and shutdowns, resulting in rapidly changing market and economic conditions. Although some of these restrictions and other containment measures have since been lifted or scaled back, ongoing surges of COVID-19 have in some cases resulted in the re-imposition of certain restrictions and containment measures, and may continue to lead to other restrictions being re-implemented in the foreseeable future in response to efforts to reduce the rapid spread of 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 pandemic. To date, its external Display Solutions business contractors and sub-contractors have not been materially impacted by the COVID-19 pandemic. The Company is, however, unable to accurately predict the full impact that the COVID-19 pandemic will have on its future results of operations due to numerous uncertainties, including the severity and duration of the outbreak, the efficacy of ongoing global vaccination efforts, potential future recurrences of the outbreak, the spread of disease variants that may be resistant to the existing vaccines, further containment actions that may be taken by governmental authorities, the impact to the businesses of its customers and suppliers, and other factors. The Company continues to closely monitor and evaluate the nature and scope of the impact of the COVID-19 pandemic to its business, consolidated results of operations, and financial condition, and may take further a ctions altering its business operations and managing its costs and liquidity that the Company deems necessary or appropriate to respond to this fast moving and uncertain global health crisis and the resulting global economic consequences. 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. , Case No. 1:21-cv-03587 (S.D.N.Y.) (the “Schulthess Complaint”), Pittman v. Magnachip Semiconductor Corporation, et al. , Case No. 1:21-cv-02306 (E.D.N.Y.), Flanagan v. Magnachip Semiconductor Corporation, et al. , Case No. 1:21-cv-03743 (S.D.N.Y.), Castelli v. Magnachip Semiconductor Corporation, et al. , Case No. 1:21-cv-03769 (S.D.N.Y.) (the “Castelli Complaint”), Doolittle v. Magnachip Semiconductor Corporation, et al. , Case No. 1:21-cv-03801 (S.D.N.Y.), Thomas v. Magnachip Semiconductor Corporation, et al. , Case No. 1:21-cv-03860 (S.D.N.Y.), Finger v. Magnachip Semiconductor Corporation, et al. , Case No. 1:21-cv-03927 (S.D.N.Y.), Kent v. Magnachip Semiconductor Corporation, et al ., Case No. 1:21-cv-00657 (D. Del.), and Kennedy v. Magnachip Semiconductor Corporation, et al. , Case No. 2:21-cv-02110 (E.D. Pa.). Each complaint alleges that the preliminary proxy statement filed by the Company with the Securities and Exchange Commission (“SEC”) on April 19, 2021 is false and/or misleading and asserts claims for violations of Section 14(a) and 20(a) of the Securities Exchange Act of 1934, as amended, and SEC Rule 14a-9 against the Company and certain current or former members of the Company’s Board of Directors. The Schulthess and Castelli Complaints also allege breaches of fiduciary duties by certain current or former members of the Company’s Board of Directors. The Schulthess Complaint further alleges that the Company aided and abetted purported breaches of fiduciary duties by certain current or former members of the Company’s Board of Directors. The Company believes the disclosures in the preliminary proxy statement comply fully with all applicable law and that the lawsuits are entirely without merit. Additional lawsuits arising out of or relating to the Merger Agreement or the Merger may be filed in the future. At this time, the Company is unable to reasonably estimate any possible loss, or range of reasonable possible losses, with respect to the complaints described above.

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

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

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

Foreign Currency Loss, Net - Additional Information (Detail) $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Foreign Currency Transaction [Abstract]
Exchange rates using first base rate	1,133.5	1,088.0
Intercompany loan balances	$ 381,800	$ 378,852

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)

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

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	$ 29.00
Business acquisition, transaction costs	$ 9,831

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

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

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

s of March 31, 2021 and December 31, 2020 are comprised of the following (in thousands):


	March 31, 2021			December 31, 2020
Buildings and related structures	$	24,110		$	24,882
Machinery and equipment		102,365			106,244
Finance lease right-of-use assets		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.

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 memory and Radio Frequency (“RF”) applications. 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 $46.5 million and Korean Won in the amount of approximately KRW 360.6 billion. In addition to the purchase price, the Buyer assumed all severance liabilities relating to the transferred employees, which had a value of approximately $100 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 for the fiscal year ended December 31, 2020. Recently Adopted Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes” (“ASU 2019-12”). ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The Company adopted ASU 2019-12 as of January 1, 2021, and the adoption of ASU 2019-12 did not have a material impact on the Company’s consolidated financial statements.

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

Accrued Expenses

3 Months Ended

Mar. 31, 2021

Payables and Accruals [Abstract]

Accrued Expenses

8. Accrued Expenses

Accrued expenses as of March 31, 2021

nd December 31, 2020 are comprised of the following (in thousands):


	March 31, 2021		December 31, 2020
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

Merger Agreement	3 Months Ended
Merger Agreement	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 $0.01 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 $29.00 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, or (iv) the other party has breached the Merger Agreement, which breach would give rise to a failure, or has materially contributed to the failure, of certain conditions to the non-breaching party’s obligations to close (subject to a cure period). Additionally, each of the Company and Parent may terminate the Merger Agreement in certain other circumstances. 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.

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

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	$ 100.0

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

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

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	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. 01, 2021	Mar. 01, 2021	Mar. 01, 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

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, 2021			December 31, 2020
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, 2021			March 31, 2020
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	)

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, 2021			March 31, 2020
	(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, 2021		March 31, 2020
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.

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 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

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, 2020 USD ($)
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)

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

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References + Details

Borrowings - Components of Long-term Borrowings (Detail) $ in Thousands	Dec. 31, 2020 USD ($)
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

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

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

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

10,144,131

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 Expenses (Tables)

3 Months Ended

Mar. 31, 2021

Payables and Accruals [Abstract]

Summary of Accrued Expenses

Accrued expenses as of March 31, 2021

nd December 31, 2020 are comprised of the following (in thousands):


	March 31, 2021		December 31, 2020
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

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, 2021			March 31, 2020
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

employees upon their normal retirement age (in thousands):


	Severance benefit
Remainder of 2021	$	79
2022		261
2023		653
2024		935
2025		2,062
2026		2,364
2027 – 2031		19,921