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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Registrant Name	MAGNACHIP SEMICONDUCTOR Corp
Trading Symbol	MX
Entity Central Index Key	0001325702
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		34,224,247

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 105,812	$ 132,438
Accounts receivable, net	92,056	80,003
Unbilled accounts receivable	27,885	38,181
Inventories, net	80,794	71,611
Other receivables	8,035	3,702
Prepaid expenses	13,781	11,133
Hedge collateral (Note 8)	3,560	5,810
Other current assets (Note 17)	7,293	9,867
Total current assets	339,216	352,745
Property, plant and equipment, net (Notes 4 and 6)	201,738	202,171
Operating lease right-of-use assets	13,046
Intangible assets, net	3,900	3,953
Long-term prepaid expenses	13,028	15,598
Other non-current assets	9,038	8,729
Total assets	579,966	583,196
Current liabilities
Accounts payable	76,031	55,631
Other accounts payable	18,884	15,168
Accrued expenses	43,481	46,250
Deferred revenue	6,907	6,477
Other current liabilities (Notes 6 and 8)	4,531	9,133
Total current liabilities	149,834	132,659
Long-term borrowings, net	303,016	303,577
Non-current operating lease liabilities	10,975
Accrued severance benefits, net	144,502	146,031
Other non-current liabilities (Note 6)	17,950	18,239
Total liabilities	626,277	600,506
Commitments and contingencies (Note 17)
Stockholders' equity
Common stock, $0.01 par value, 150,000,000 shares authorized, 43,230,535 shares issued and 34,223,502 outstanding at March 31, 2019 and 43,054,458 shares issued and 34,441,232 outstanding at December 31, 2018	433	431
Additional paid-in capital	143,315	142,600
Accumulated deficit	(70,430)	(36,305)
Treasury stock, 9,007,033 shares at March 31, 2019 and 8,613,226 shares at December 31, 2018, respectively	(106,511)	(103,926)
Accumulated other comprehensive loss	(13,118)	(20,110)
Total stockholders' deficit	(46,311)	(17,310)
Total liabilities and stockholders' equity	$ 579,966	$ 583,196

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
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	43,230,535	43,054,458
Common stock, shares outstanding	34,223,502	34,441,232
Treasury stock, shares	9,007,033	8,613,226

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 157,380	$ 165,819
Cost of sales	134,679	121,238
Gross profit	22,701	44,581
Operating expenses
Selling, general and administrative expenses	18,070	17,622
Research and development expenses	20,018	19,580
Restructuring and other charges	2,894
Total operating expenses	40,982	37,202
Operating income (loss)	(18,281)	7,379
Interest expense	(5,637)	(5,463)
Foreign currency gain (loss), net	(9,997)	1,318
Loss on early extinguishment of long-term borrowings, net	(42)
Other income, net	673	519
Income (loss) before income taxes	(33,284)	3,753
Income tax expenses	841	990
Net income (loss)	$ (34,125)	$ 2,763
Earnings (loss) per common share—
Basic	$ (1.00)	$ 0.08
Diluted	$ (1.00)	$ 0.08
Weighted average number of shares—
Basic	34,194,878	34,253,111
Diluted	34,194,878	35,154,693

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME / (LOSS) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (34,125)	$ 2,763
Other comprehensive income (loss)
Foreign currency translation adjustments	7,304	(483)
Derivative adjustments
Fair valuation of derivatives	(499)	(67)
Reclassification adjustment for loss (gain) on derivatives included in net income (loss)	187	(2,606)
Total other comprehensive income (loss)	6,992	(3,156)
Total comprehensive loss	$ (27,133)	$ (393)

- Definition

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

+ References + Details

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock Outstanding [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Balance beginning at Dec. 31, 2017	$ (39,637)		$ 426	$ 136,259	$ (40,889)	$ (102,319)	$ (33,114)
Impact of adopting the new revenue standard at Mar. 31, 2018	8,484				8,484
Balance as adjusted, beginning at Dec. 31, 2017	(31,153)		426	136,259	(32,405)	(102,319)	(33,114)
Balance, Shares beginning at Dec. 31, 2017		34,189,599
Stock-based compensation	1,469			1,469
Exercise of stock options	143		1	142
Exercise of stock options, Shares		21,894
Settlement of restricted stock units			1	(1)
Settlement of restricted stock units, Shares		163,466
Other comprehensive income (loss), net	(3,156)						(3,156)
Net income (loss)	2,763				2,763
Balance ending at Mar. 31, 2018	(29,934)		428	137,869	(29,642)	(102,319)	(36,270)
Balance, Shares ending at Mar. 31, 2018		34,374,959
Balance beginning at Dec. 31, 2018	$ (17,310)		431	142,600	(36,305)	(103,926)	(20,110)
Balance, Shares beginning at Dec. 31, 2018	34,441,232	34,441,232
Stock-based compensation	$ 669			669
Exercise of stock options	48		0	48
Exercise of stock options, Shares		8,624
Settlement of restricted stock units			2	(2)
Settlement of restricted stock units, Shares		167,453
Acquisition of treasury stock	(2,585)					(2,585)
Acquisition of treasury stock, Shares		(393,807)
Other comprehensive income (loss), net	6,992						6,992
Net income (loss)	(34,125)				(34,125)
Balance ending at Mar. 31, 2019	$ (46,311)		$ 433	$ 143,315	$ (70,430)	$ (106,511)	$ (13,118)
Balance, Shares ending at Mar. 31, 2019	34,223,502	34,223,502

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net income (loss)	$ (34,125)	$ 2,763
Adjustments to reconcile net income (loss) to net cash used in operating activities
Depreciation and amortization	8,303	7,958
Provision for severance benefits	3,117	4,512
Amortization of debt issuance costs and original issue discount	571	532
Loss (gain) on foreign currency, net	11,720	(1,682)
Restructuring and other charges	2,894
Stock-based compensation	669	1,469
Loss on early extinguishment of long-term borrowings, net	42
Other	96	(337)
Changes in operating assets and liabilities
Accounts receivable, net	(12,844)	3,115
Unbilled accounts receivable	9,726	(639)
Inventories, net	(10,585)	(13,150)
Other receivables	(4,205)	(3,746)
Other current assets	1,836	(1,071)
Accounts payable	20,874	3,168
Other accounts payable	2,725	(2,759)
Accrued expenses	(5,365)	(7,129)
Deferred revenue	555	4,809
Other current liabilities	(6,848)	(570)
Other non-current liabilities	1,085	618
Payment of severance benefits	(2,263)	(2,247)
Other	347	465
Net cash used in operating activities	(11,675)	(3,921)
Cash flows from investing activities
Proceeds from settlement of hedge collateral	2,242	4,863
Purchase of plant, property and equipment	(11,207)	(7,329)
Payment for intellectual property registration	(232)	(409)
Collection of guarantee deposits	298	14
Payment of guarantee deposits	(892)
Other	(10)	(36)
Net cash used in investing activities	(9,801)	(2,897)
Cash flows from financing activities
Repurchase of long-term borrowings	(1,175)
Proceeds from exercise of stock options	48	142
Acquisition of treasury stock	(2,353)
Repayment of financing related to water treatment facility arrangement	(143)
Repayment of principal portion of finance lease liabilities	(59)
Net cash provided by (used in) financing activities	(3,682)	142
Effect of exchange rates on cash, cash equivalents and restricted cash	(1,468)	1,237
Net decrease in cash, cash equivalents and restricted cash	(26,626)	(5,439)
Cash, cash equivalents and restricted cash
Beginning of the period	132,438	128,575
End of the period	105,812	123,136
Supplemental cash flow information
Cash paid for interest	9,549	9,609
Cash paid for income taxes	1,556	6
Non-cash investing and financing activities
Property, plant and equipment additions in other accounts payable	2,643	$ 1,202
Acquisition Of Treasury Stock Related To Tax With holding For Share Based Compensation	$ (232)

Business, Basis of Presentation and Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Business, Basis of Presentation and Summary of 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. The Company’s business is comprised of two operating segments: Foundry Services Group and Standard Products Group. The Company’s Foundry Services Group provides specialty analog and mixed-signal foundry services mainly for fabless and Integrated Device Manufacturer (“IDM”) semiconductor companies that primarily serve communications, IoT, consumer, industrial and automotive applications. The Company’s Standard Products Group is comprised of two business lines: Display Solutions and Power Solutions. 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 (“US GAAP”). These interim consolidated financial statements include normal recurring adjustments and the elimination of all intercompany accounts and transactions which are, in the opinion of management, necessary to provide a fair statement of the Company’s financial condition and results of operations for the periods presented. These interim consolidated financial statements are presented in accordance with Accounting Standards Codification 270,

“Interim

Reporting”

and, accordingly, do not include all of the information and note disclosures required by US GAAP for complete financial statements, except for the changes below. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results to be expected for a full year or for any other periods.

The December 31, 2018 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by US GAAP.

Upon the adoption of Accounting Standards Update No. 2016-02, “Leases (Topic 842)” (“ASU 2016-02”) effective on January 1, 2019 (the “new lease standard”), the Company has updated its accounting policy for leases as detailed below.

Leases

The Company determines if an arrangement is a lease at inception of a contract considering whether the arrangement conveys the right to control the use of an identified asset over the period of use. Control of an underlying asset is conveyed if the Company has the right to direct the use of, and to obtain substantially all of the economic benefits from the use of, the identified asset. The Company accounts for lease transactions as either an operating or a finance lease, depending on the terms of the underlying lease arrangement. Assets related to operating leases are recorded on the balance sheet as operating lease right-of-use assets; the related liabilities are recorded as other current liabilities for the current portion and other non-current operating lease liabilities for the non-current portion. Finance lease right-of-use assets are included in property and equipment, net and the related lease liabilities are included in other current liabilities and other non-current liabilities on the consolidated balance sheets.

Right-of-use assets represent the Company’s right to use an underlying asset during the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Right-of-use assets and liabilities are recognized based on the present value of the future minimum lease payments over the lease term. As most of the Company’s leases do not provide a readily determinable implicit rate, the Company estimates its incremental borrowing rates in determining the present value of future payments based on the lease term of each lease and market information available at commencement date. Fixed lease expenses for operating leases and depreciation expenses for finance leases are recognized on a straight-line basis over the respective lease term.

An extension or contraction of a lease term is considered if the related option to extend or early terminate the lease is reasonably certain to be exercised by the Company. Operating lease right-of-use assets may also include any advance lease payments made and exclude lease incentives and initial direct costs incurred. The Company has lease agreements with lease and non-lease components, which are generally accounted for separately. For certain equipment leases, lease and non-lease components are accounted for as a single lease component.

Variable lease payment amounts that cannot be determined at the commencement of the lease such as increases in lease payments based on changes in index rates are not included in the right-of-use assets or liabilities. These variable lease payments are expensed as incurred.

The Company does not recognize operating lease right-of-use assets and operating lease liabilities that arise from short-term leases but rather recognizes fixed lease payments in the statements of operations on a straight-line basis and variable payments in the period in which the related obligations incur.

Revenue Recognition

The Company recognizes revenue when it satisfies the performance obligation of transferring control over a product or service to a customer. Revenue is measured based on the consideration specified in a contract with a customer, which consideration is paid in exchange for a product or service.

The Foundry Services Group of the Company manufactures products, which we refer to as foundry products, based on customers’ specific product designs. The Company recognizes revenue over time for foundry products that do not have an alternative use when the Company has an enforceable right to payment. Revenue recognized over time is in proportion of wafer manufacturing costs incurred relative to total estimated costs for completion. However, in certain circumstances, pursuant to a customer contract or an individual purchase order, the Company may not have an enforceable right to payment for services performed at a given time. In this situation, the Company recognizes revenue at the time when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement.

The Standards Products Group of the Company sells products manufactured based on the Company’s design. The Standard Products Group’s products are either standardized with an alternative use or the Company does not have an enforceable right to payment for the related manufacturing services completed to date. For those products, revenue is recognized when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement.

A portion of the Company’s sales are made through distributors for which the Company applies the same revenue recognition guidance described above. The Company defers the recognition of revenue when a distributor receives consideration from the customers prior to the

fulfillment of performance obligations.

These amounts are classified as deferred revenue on the consolidated balance sheets. Of the recorded deferred revenue of $6,477 thousand as of December 31, 2018, $1,436 thousand were recognized as revenue during the three months ended March 31, 2019 and of the recorded deferred revenue of $

8,335

thousand as of December 31, 2017, $1,086 thousand was recognized as revenue during the three months ended March 31, 2018, respectively.

In accordance with revenue recognition guidance, any tax assessed by a governmental authority that is both imposed on and concurrent with a specific revenue-producing transaction, and that is collected by the Company from a customer, is excluded from revenue and presented in the statement of operations on a net basis.

The Company provides

warranties

under which customers can return defective products. The Company also provides allowances for additional products that may have to be provided free of charge to compensate customers for not meeting previously agreed upon yield criteria, which the Company refers to as the low yield compensation reserve. The Company estimates the costs related to warranty claims, repair or replacements and low yield compensation reserves, and records them as components of cost of sales.

In addition, the Company offers sales returns (other than those that relate to defective products under warranty), cash discounts for early payments, volume discounts and certain allowances to the Company’s customers, including the Company’s distributors. The Company records reserves for those returns, discounts and allowances as a deduction from sales, based on historical experience and other quantitative and qualitative factors.

Substantially all of the Company’s contracts are one year or less in duration.

The standard payment terms with customers are generally thirty to sixty days from the time of shipment, product delivery to the customer’s location or customer acceptance, depending on the terms of the related arrangement.

Unbilled accounts receivable represents the Company’s contractual right to consideration for manufacturing work performed on a customer contract or an individual purchase order, which has not been invoiced to the customer. Of the recorded unbilled accounts receivable of $38,181 thousand as of December 31, 2018, $22,470 thousand were billed to customers upon shipment, upon product delivery or upon customer acceptance, depending on the terms of the related arrangement, during the three months ended March 31, 2019.

Recent Accounting Pronouncements

In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2018-13 “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement” (“ASU 2018-13”). ASU 2018-13 amends existing fair value measurement disclosure requirements by adding, changing, or removing certain disclosures. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted for any eliminated or modified disclosures. The Company does not expect that the adoption will have an impact on the Company’s consolidated financial statements.

Recently Adopted Accounting Pronouncements

In February 2018, the FASB issued Accounting Standards Update No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220) Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income which allows for a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Act. The Company adopted ASU 2018-02 in the first quarter of 2019, and the adoption did not impact the Company’s consolidated financial statements and related disclosures.

In August 2017, the FASB issued Accounting Standards Update No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” (“ASU 2017-12”). ASU 2017-12 provides new guidance about income statement classification and eliminates the requirement to separately measure and report hedge ineffectiveness. The entire change in fair value for qualifying hedge instruments included in the effectiveness will be recorded in other comprehensive income (OCI) and amounts deferred in OCI will be reclassified to earnings in the same income statement line item in which the earnings effect of the hedged item is reported. The Company adopted ASU 2017-12 in the first quarter of 2019, and the adoption of ASU 2017-12 did not have a material impact to the Company’s consolidated financial statements.

In July 2017, the FASB issued Accounting Standards Update No. 2017-11, “Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815)” (“ASU 2017-11”), which addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. Current accounting guidance creates cost and complexity for entities that issue financial instruments (such as warrants and convertible instruments) with down round features that require fair value measurement of the entire instrument or conversion option. The Company adopted ASU 2017-11 in the first quarter of 2019, and the adoption did not impact the Company’s consolidated financial statements.

In February 2016, the FASB issued Accounting Standards Update No. 2016-02, “Leases (Topic 842)” (“ASU 2016-02”) in order to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under US GAAP. ASU 2016-02 requires that a lessee recognize a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term on the balance sheet. The FASB issued Accounting Standards Update No 2018-01, “Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842” (“ASU 2018-01”). ASU 2018-01 permits an entity to elect an optional transition practical expedient not to evaluate land easements that exist or expired before the entity’s adoption of ASU 2016-02 and that were not accounted for as leases under previous lease guidance. In July 2018, the FASB issued Accounting Standards Update No 2018-10, “Codification Improvements to Topic 842 Leases” (“ASU 2018-10”). ASU 2018-10 provides narrow amendments to clarify how to apply certain aspects of the new lease standard. In July 2018, the FASB also issued Accounting Standards Update No 2018-11, “Leases (Topic 842) Targeted Improvements” (“ASU 2018-11”). ASU 2018-11 allows an entity to recognize a cumulative-effect adjustment to the opening balance of retained earnings upon adoption of ASU 2016-02 (the “modified retrospective transition method”). In December 2018, the FASB issued Accounting Standards Update No 2018-20, “Leases (Topic 842) Narrow Scope Improvements for Lessors” (“ASU 2018-20”). ASU 2018-20 provides certain amendments that affect narrow aspects of the guidance issued in ASU 2016-02. In March 2019, the FASB issued Accounting Standards Update No 2019-01 “Codification Improvements” (“ASU 2019-01”) .The effective date and transition requirements for ASU 2016-02, ASU 2018-01, ASU 2018-10, ASU 2018-11, ASU 2018-20 and ASU 2019-01 are the same.

The Company adopted the new lease standard as of January 1, 2019, using the modified retrospective transition method, which requires a cumulative effect adjustment, if any, to the Company’s beginning equity to be recognized on the date of adoption. There was no cumulative effect adjustment recorded on January 1, 2019. Accordingly, all periods prior to January 1, 2019 were presented in accordance with the previous ASC Topic 840, Leases, and no retrospective adjustments were made to the comparative periods presented. The impact from the adoption was the balance sheet recognition of ROU assets and lease liabilities for operating and finance leases as a lessee, which resulted in an increase of $16,387 thousand in the total assets and liabilities of the Company’s consolidated balance sheets as of January 1, 2019. In addition, the adoption did not materially impact the Company’s consolidated statements of operations or cash flows for the three months ended March 31, 2019. For further information regarding these impacts, see Note 6 “Leases.”

Sales of Accounts Receivable and Receivable Discount Program

3 Months Ended

Mar. 31, 2019

Receivables [Abstract]

Sales of Accounts Receivable and Receivable Discount Program

2. Sales of Accounts Receivable and Receivable Discount Program

The Company has entered into an agreement to sell selected trade accounts receivable to a financial institution from time to time since March 2012. After the sale, the Company does not retain any interest in the receivables and the applicable financial institution collects these accounts receivable directly from the customer. The proceeds from the sales of these accounts receivable totaled $7,989 thousand and $3,662 thousand for the three months ended March 31, 2019 and 2018, respectively, and these sales resulted in pre-tax losses of $25 thousand and $2 thousand for the three months ended March 31, 2019 and 2018, respectively, which are included in selling, general and administrative expenses in the consolidated statements of operations. Net proceeds of this accounts receivable sale program are recognized in the consolidated statements of cash flows as part of operating cash flows.

The Company uses receivable discount programs with certain customers. These discount arrangements allow the Company to accelerate collection of customers’ receivables.

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventories

3 Months Ended

Mar. 31, 2019

Inventory Disclosure [Abstract]

Inventories

3. Inventories

Inventories as of March 31, 2019 and December 31, 2018 consist of the following (in thousands):

	March 31, 2019			December 31, 2018
Finished goods	$	17,519		$	14,334
Semi-finished goods and work-in-process		49,191			39,135
Raw materials		22,145			21,150
Materials in-transit		690			1,890
Less: inventory reserve		(8,751	)		(4,898	)
Inventories, net	$	80,794		$	71,611

Changes in inventory reserve for the three months ended March 31, 2019 and 2018 are as follows (in thousands):

	Three Months Ended
	March 31, 2019			March 31, 2018
Beginning balance	$	(4,898	)	$	(6,391	)
Change in reserve
Inventory reserve charged to costs of sales		(5,174	)		(1,620	)
Sale of previously reserved inventory		474			831
		(4,700	)		(789	)
Write off		664			2,530
Translation adjustments		183			(21	)
Ending balance	$	(8,751	)	$	(4,671	)

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.

Property, Plant and Equipment

3 Months Ended

Mar. 31, 2019

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

4. Property, Plant and Equipment

Property, plant and equipment as of March 31, 2019 and December 31, 2018 are comprised of the following (in thousands):

	March 31, 2019			December 31, 2018
Buildings and related structures	$	69,539		$	70,665
Machinery and equipment		322,352			323,325
Finance lease right-of-use assets		2,500			—
Others		47,794			44,724
		442,185			438,714
Less: accumulated depreciation		(255,599	)		(251,962	)
Land		15,152			15,419
Property, plant and equipment, net	$	201,738		$	202,171

Aggregate depreciation expenses totaled $8,087 thousand and $7,757 thousand for the three months ended March 31, 2019 and 2018, respectively.

As of June 29, 2018, the Company’s Korean subsidiary entered into an arrangement whereby it acquired a water treatment facility to support its fab in Gumi, Korea from SK Hynix for $4,172 thousand, and sold it for $4,172 thousand to a third party management company that the Company has engaged to run the facility for a

-year term. This arrangement is accounted for as a financing due to the Company’s Korean subsidiary’s continuing involvement with the facility. As a result, on an acquisition date, the Company recorded the water treatment facility of $4,172 thousand as property, plant and equipment, net, which is depreciated over its estimated useful life. The Company also recorded the related liabilities of $553 thousand as other current liabilities and $3,619 thousand as other non-current liabilities, which relates to the financing and service portion of the arrangement and is amortized using the effective interest method over the contract period.

Intangible Assets

3 Months Ended

Mar. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

5. Intangible Assets

Intangible assets as of March 31, 2019 and December 31, 2018 are comprised of the following (in thousands):

	March 31, 2019
	Gross amount		Accumulated amortization			Net amount
Technology	$	19,015	$	(19,015	)	$	—
Customer relationships		27,310		(27,310	)		—
Intellectual property assets		11,601		(7,701	)		3,900
Intangible assets, net	$	57,926	$	(54,026	)	$	3,900

	December 31, 2018
	Gross amount		Accumulated amortization			Net amount
Technology	$	19,350	$	(19,350	)	$	—
Customer relationships		27,791		(27,791	)		—
Intellectual property assets		11,571		(7,618	)		3,953
Intangible assets, net	$	58,712	$	(54,759	)	$	3,953

Aggregate amortization expenses for intangible assets totaled $216 thousand and $201 thousand for the three months ended March 31, 2019 and 2018, respectively.

Leases

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Leases

6. Leases

The Company has operating and finance leases for land, buildings and other assets such as vehicles and office equipment. The Company’s leases have remaining lease terms

ranging from

1 year to 15 years. For certain leases, the Company has options to extend the lease term for additional periods ranging from 1 year to 10 years.

The Company used hindsight for determining the remaining lease term and assessing the likelihood of whether these renewal options are reasonably certain to be exercised by the Company.

The Company’s land lease payment is subject to a biennial adjustment (based on change of the Consumer Price Index), the impact of which is treated as a variable lease payment.

The Company adopted the new lease accounting standard as of January 1, 2019 using the modified retrospective transition method. The tables below present financial information related to the Company’s leases as of, and for the three months ended, March 31, 2019.

Supplemental balance sheet information related to leases is as follows (in thousands):

Leases	Classification	As of March 31, 2019
Assets
Operating lease	Operating lease right-of-use assets	$	13,046
Finance lease	Property, plant and equipment, net		2,422
Total leased assets		$	15,468
Liabilities
Current
Operating	Other current liabilities	$	2,072
Finance	Other current liabilities		242
Non-current
Operating	Non-current operating lease liabilities		10,975
Finance	Other non-current liabilities		2,199
Total lease liabilities		$	15,488

The components of lease cost included in the Company’s consolidated statements of operations, are as follows (in thousands):

	Three Months Ended
	March 31, 2019
Operating lease cost	$	828
Finance lease cost
Amortization of right-of-use assets		78
Interest on lease liabilities		47
Total lease cost	$	953

The above table does not include an immaterial cost of short-term leases and there was no variable lease payment during the three months ended March 31, 2019

Other lease information is as follows (in thousands):

	Three Months Ended
	March 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$	828
Operating cash flows from finance leases		47
Financing cash flows from finance leases		59
Weighted average remaining lease term
Operating leases		12.3 years
Finance leases		10.8 years
Weighted average discount rate
Operating leases		7.93	%
Finance leases		7.94	%

The aggregate future lease payments for operating and finance leases as of March 31, 2019 are as follows (in thousands):

	Operating Leases			Finance Leases
2019	$	2,289		$	316
2020		2,705			421
2021		1,346			421
2022		1,113			421
2023		1,107			421
Thereafter		11,913			1,639
Total future lease payments		20,473			3,639
Less: Present value adjustment		(7,426	)		(1,198	)
Present value of future payments	$	13,047		$	2,441

As of December 31, 2018, the minimum aggregate rental payments due under non-cancelable operating lease contracts are as follows (in thousands):


2019	$	4,319
2020		3,569
2021		1,570
2022		1,319
2023		1,309
2024 and thereafter		13,978

	$	26,064

Accrued Expenses

3 Months Ended

Mar. 31, 2019

Payables and Accruals [Abstract]

Accrued Expenses

Accrued expenses as of March 31, 2019 and December 31, 2018 are comprised of the following (in thousands):

	March 31, 2019		December 31, 2018
Payroll, benefits and related taxes, excluding severance benefits	$	15,782	$	14,548
Withholding tax attributable to intercompany interest income		21,030		20,879
Interest on senior notes		3,444		8,226
Outside service fees		1,064		935
Others		2,161		1,662
Accrued expenses	$	43,481	$	46,250

Derivative Financial Instruments

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

8. Derivative Financial Instruments

The Company’s Korean subsidiary from time to time has entered into zero cost collar and forward contracts to hedge the risk of changes in the functional-currency-equivalent cash flows attributable to currency rate changes on U.S. dollar denominated revenues.

Details of derivative contracts as of March 31, 2019 are as follows (in thousands):

Date of transaction	Type of derivative	Total notional amount		Month of settlement
June 27, 2018	Zero cost collar	$	9,000	April 2019 to June 2019
June 27, 2018	Forward	$	18,000	April 2019 to June 2019

Details of derivative contracts as of December 31, 2018 are as follows (in thousands):

Date of transaction	Type of derivative	Total notional amount		Month of settlement
June 27, 2018	Zero cost collar	$	18,000	January 2019 to June 2019
June 27, 2018	Forward	$	36,000	January 2019 to June 2019

The zero cost collar and forward contracts qualify as cash flow hedges under ASC 815, “Derivatives and Hedging,” since at both the inception of the contracts and on an ongoing basis, the hedging relationship was and is expected to be highly effective in achieving offsetting cash flows attributable to the hedged risk during the term of the contracts.

The fair values of the Company’s outstanding zero cost collar and forward contracts recorded as assets and liabilities as of March 31, 2019 and December 31, 2018 are as follows (in thousands):

Derivatives designated as hedging instruments:		March 31, 2019		December 31, 2018
Liability Derivatives:
Zero cost collars	Other current liabilities	$	67	$	117
Forward	Other current liabilities	$	654	$	607

Offsetting of derivative liabilities as of March 31, 2019 is as follows (in thousands):

As of March 31, 2019	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets		Net amounts of liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets					Net amount
As of March 31, 2019	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged			Net amount
Liability Derivatives:
Zero cost collars	$	67	$	—	$	67	$	—	$	(50	)	$	17
Forward	$	654	$	—	$	654	$	—	$	(210	)	$	444

Offsetting of derivative liabilities as of December 31, 2018 is as follows (in thousands):

As of December 31, 2018	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets		Net amounts of liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets
As of December 31, 2018	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged			Net amount
Liability Derivatives:
Zero cost collars	$	117	$	—	$	117	$	—	$	(360	)	$	(243	)
Forward	$	607	$	—	$	607	$	—	$	(1,450	)	$	(843	)

For derivative instruments that are designated and qualify as cash flow hedges, gains or losses on the derivative aside from components excluded from the assessment of effectiveness, are reported as a component of accumulated other comprehensive income (“AOCI”) and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative, representing hedge components excluded from the assessment of effectiveness, are recognized in current earnings.

The following table summarizes the impact of derivative instruments on the consolidated statement of operations for the three months ended March 31, 2019 and 2018 (in thousands):

Derivatives in ASC 815 Cash Flow Hedging Relationships	Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)						Location /Amount of Gain (Loss) Reclassified from AOCI Into Statement of Operations (Effective Portion) (1)						Location /Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion) (1)
	Three Months Ended March 31,							Three Months Ended March 31,						Three Months Ended March 31,
	2019			2018				2019			2018			2019			2018
Zero cost collars	$	34		$	(132	)	Net sales	$	—		$	1,326	Other income, net	$	—		$	(71	)
Forwards	$	(533	)	$	65		Net sales	$	(89	)	$	1,280	Other income, net	$	(56	)	$	22
Forwards—excluded time value (1)	$	—		$	—		Net sales	$	(98	)	$	—	Other income, net	$	—		$	(27	)
	$	(499	)	$	(67	)		$	(187	)	$	2,606		$	(56	)	$	(76	)
							Total Revenue	$	157,380		$	165,819

(1)

The FASB issued the new guidance about hedging activities (ASU

2017

12)

, which provides new rule about income statement classification and eliminates the requirement to separately measure and report hedge ineffectiveness. In addition, under the same guidance, excluded time value for forward contracts is presented in earnings in the same income statement line item that is used to present the earnings effect of the hedged item. The Company adopted the new guidance in the first quarter of

2019

and the comparative prior period amounts were not restated and continued to be reported under the accounting standards in effect for such period.

As of March 31, 2019, the amount expected to be reclassified from accumulated other comprehensive loss into loss within the next twelve months is $361 thousand.

The Company set aside $3,300 thousand and $4,000 thousand in cash deposits to the counterparty, Nomura Financial Investment (Korea) Co., Ltd. (“NFIK”) as required for the zero cost collar and forward contracts outstanding as of March 31, 2019 and December 31, 2018, respectively. These cash deposits are recorded as hedge collateral on the consolidated balance sheets.

The Company is required to deposit additional cash collateral with NFIK for any exposure in excess of $500 thousand, and $260 thousand and $1,810 thousand of additional cash collateral were required and recorded as hedge collateral on the consolidated balance sheets as of March 31, 2019 and December 31, 2018, respectively. These outstanding zero cost collar and forward contracts are subject to termination if the sum of qualified and unrestricted cash and cash equivalents held by the Company is less than $30,000 thousand on the last day of a fiscal quarter.

Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

9. Fair Value Measurements

Fair Value of Financial Instruments

As of March 31, 2019, the following table represents the Company’s liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands):

	Carrying Value March 31, 2019		Fair Value Measurement March 31, 2019		Quoted Prices in Active Markets for Identical Asset (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Liabilities:
Derivative liabilities (other current liabilities)	$	721	$	721		—	$	721		—

As of December 31, 2018, the following table represents the Company’s liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands):

	Carrying Value December 31, 2018		Fair Value Measurement December 31, 2018		Quoted Prices in Active Markets for Identical Asset (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Liabilities:
Derivative liabilities (other current liabilities)	$	724	$	724		—	$	724		—

Items not reflected in the table above include cash equivalents, accounts receivable, other receivables, accounts payable, and other accounts payable, fair value of which approximate carrying values due to the short-term nature of these instruments. The fair value of assets and liabilities whose carrying value approximates fair value is determined using Level 2 inputs.

Fair Value of Long-term Borrowings

	March 31, 2019				December 31, 2018
	Carrying Value		Fair Value		Carrying Value		Fair Value
	(In thousands of US dollars)
Long-term Borrowings:
5.0% Exchangeable Senior Notes due March 2021 (Level 2)	$	80,889	$	97,666	$	81,418	$	86,835
6.625% Senior Notes due July 2021 (Level 2)	$	222,126	$	213,038	$	222,159	$	202,046

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, 202

1 (the “Exchangeable Notes”) of $86,250 thousand, which represents the principal amount, excluding $5,902 thousand of debt issuance costs. In December 2018 and In 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 Company estimates the fair value of the Exchangeable Notes using the market approach, which utilizes quoted market prices that fall under Level 2. For further description of the Exchangeable Notes, see Note 10, “Long-term Borrowings.”

On July 18, 2013, the Company issued 6.625% senior notes due July 15, 2021 (the “2021 Notes”) of $225.0 million, which represents the principal amount, excluding $1.1 million of original issue discount and $5.0 million of debt issuance costs. In December 2018 and In January 2019, the Company repurchased a principal amount equal to $500 thousand and $250 thousand,

respectively,

of the 2021 Notes in the open market. The Company estimates the fair value of the 2021 Notes using the market approach, which utilizes quoted market prices that fall under Level 2. For further description of the 2021 Notes, see Note 10, “Long-term 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, 2019 and 2018, 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

Long-term Borrowings

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Long-term Borrowings

10. Long-Term Borrowings

Long-term borrowings as of March 31, 2019 and December 31, 2018 are as follows (in thousands):

	March 31, 2019			December 31, 2018
5.0% Exchangeable Senior Notes due March 2021	$	83,740		$	84,660
6.625% Senior Notes due July 2021	$	224,250		$	224,500
Less: unamortized discount and debt issuance costs		(4,974	)		(5,583	)
Long-term borrowings, net of unamortized discount and debt issuance costs	$	303,016		$	303,577

5.0% Exchangeable Senior Notes

On January 17, 2017, MagnaChip Semiconductor S.A. closed the Exchangeable Notes Offering of $86,250 thousand aggregate principal amount of 5.0% Exchangeable Notes. Interest on the Exchangeable Notes accrues at a rate of 5.0% per annum, payable semi-annually on March 1 and September 1 of each year, beginning on March 1, 2017. The Exchangeable Notes will mature on March 1, 2021, unless earlier repurchased or converted. Holders may convert their notes at their option at any time prior to the close of business on the business day immediately preceding the stated maturity date.

The Company used a portion of the net proceeds from the issuance to repurchase 1,795,444 shares of common stock under its stock repurchase program at an aggregate cost of $11,401 thousand.

Upon conversion, the Company will deliver for each $1,000 principal amount of converted notes a number of shares equally to the exchange rate, which will initially be 121.1387 shares of common stock per $1,000 principal amount of Exchangeable Notes, equivalent to an initial exchange price of approximately $8.26 per share of common stock. The exchange rate will be subject to adjustment in some circumstances, but will not be adjusted for any accrued and unpaid interest. In addition, if a “make-whole fundamental change” (as defined in the Exchangeable Notes indenture (the “Exchangeable Notes Indenture”)) occurs prior to the stated maturity date, the Company will increase the exchange rate for a holder who elects to convert its notes in connection with such make-whole fundamental change in certain circumstances. MagnaChip Semiconductor S.A. may also, under certain circumstances, be required to pay additional amounts to holders of Exchangeable Notes if withholding or deduction is required in a relevant tax jurisdiction.

If the Company undergoes a fundamental change, subject to certain conditions, holders may require the Company to repurchase for cash all or part of their notes at a purchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change purchase date. In addition, upon certain events of default described in the Exchangeable Notes Indenture, the trustee or holders of at least 25% principal amount of the Exchangeable Notes may declare 100% of the then outstanding Exchangeable Notes due and payable in full, together with all accrued and unpaid interest thereon. Payment of principal on the Exchangeable Notes may also accelerate and become automatically due and payable upon certain events of default involving bankruptcy or insolvency proceedings involving the Company, MagnaChip Semiconductor S.A. and their significant subsidiaries. The Exchangeable Notes are not redeemable at the option of MagnaChip Semiconductor S.A. prior to the maturity date.

The Exchangeable Notes Indenture contains covenants that limit the ability of the Company, MagnaChip Semiconductor S.A. and the Company’s other restricted subsidiaries to: (i) declare or pay any dividend or make any payment or distribution on account of or purchase or redeem the Company’s capital stock or equity interests of the restricted subsidiaries; (ii) make any principal payment on, or redeem or repurchase, prior to any scheduled repayment or maturity, any subordinated indebtedness; (iii) make certain investments; (iv) incur additional indebtedness and issue certain types of capital stock; (v) create or incur any lien (except for permitted liens) that secures obligations under any indebtedness; (vi) merge with or into or sell all or substantially all of the Company’s assets to other companies; (vii) enter into certain types of transactions with affiliates; (viii) guarantee the payment of any indebtedness; and (ix) designate unrestricted subsidiaries.

These covenants are subject to a number of exceptions and qualifications. Certain of these restrictive covenants will terminate if the Exchangeable Notes are rated investment grade at any time.

The Company incurred debt issuance costs of $5,902 thousand related to the issuance of the Exchangeable Notes. The debt issuance costs are recorded as a direct deduction from the long-term borrowings in the consolidated balance sheets and amortized to interest expense using the effective interest method over the term of the Exchangeable Notes. Interest expense related to the Exchangeable Notes for the three months ended March 31, 2019 and 2018 was $1,408 thousand and $1,411 thousand, respectively.

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 long-term borrowings, net in the consolidated statements of operations for the year ended December 31, 2018. 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 long-term borrowings, net in the consolidated statements of operations for the three months ended March 31, 2019.

6.625% Senior Notes

On July 18, 2013, the Company issued a $225,000,000 aggregate principal amount of the 2021 Notes at a price of 99.5%. Interest on the 2021 Notes accrues at a rate of 6.625% per annum, payable semi-annually on January 15 and July 15 of each year, beginning on January 15, 2014.

The Company can optionally redeem all or a part of the 2021 Notes according to the following schedule: on or after July 15, 2017, the Company may on any one or more occasions redeem all or a part of the 2021 Notes, at a redemption price equal to 101.656% and 100% of the principal amount of the notes redeemed on or after July 15, 2018 and 2019, respectively, plus accrued and unpaid interest and special interest, if any, on the notes redeemed, to the applicable date of redemption.

The Indenture relating to the 2021 Notes contains covenants that limit the ability of the Company and its restricted subsidiaries to: (i) declare or pay any dividend or make any payment or distribution on account of or purchase or redeem the Company’s capital stock or equity interests of the restricted subsidiaries; (ii) make any principal payment on, or redeem or repurchase, prior to any scheduled repayment or maturity, any subordinated indebtedness; (iii) make certain investments; (iv) incur additional indebtedness and issue certain types of capital stock; (v) create or incur any lien (except for permitted liens) that secures obligations under any indebtedness; (vi) merge with or into or sell all or substantially all of the Company’s assets to other companies; (vii) enter into certain types of transactions with affiliates; (viii) guarantee the payment of any indebtedness; (ix) enter into sale-leaseback transactions; (x) enter into agreements that would restrict the ability of the restricted subsidiaries to make distributions with respect to their equity to the Company or other restricted subsidiaries, to make loans to the Company or other restricted subsidiaries or to transfer assets to the Company or other restricted subsidiaries; and (xi) designate unrestricted subsidiaries.

These covenants are subject to a number of exceptions and qualifications. Certain of these restrictive covenants will terminate if the 2021 Notes are rated investment grade at any time.

The Company incurred original issue discount of $1,125 thousand and debt issuance costs of $5,039 thousand related to the issuance of the 2021 Notes. The original issue discount and the debt issuance costs are recorded as a direct deduction from the long-term borrowings in the consolidated balance sheets and amortized to interest expense using the effective interest method over the term of the 2021 Notes. Interest expenses related to the 2021 Notes for the three months ended March 31, 2019 and 2018 were $3,930 thousand and $3,926 thousand, respectively.

In December 2018, the Company repurchased a principal amount equal to $500 thousand of the 2021 Notes in the open market, resulting in a net gain of $28 thousand, which was recorded as loss on early extinguishment of long-term borrowings, net in the consolidated statements of operations for the year ended December 31, 2018. In January 2019, the Company repurchased a principal amount equal to $250 thousand of the 2021 Notes in the open market, resulting in a net gain of $21 thousand, which was recorded as loss on early extinguishment of long-term borrowings, net in the consolidated statements of operations for the three months ended March 31, 2019.

Accrued Severance Benefits

3 Months Ended

Mar. 31, 2019

Postemployment Benefits [Abstract]

Accrued Severance Benefits

11. 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, 2019, 98% of employees of the Company were eligible for severance benefits.

Changes in accrued severance benefits are as follows (in thousands):

	Three Months Ended
	March 31, 2019			March 31, 2018
Beginning balance	$	149,408		$	149,795
Provisions		3,117			4,512
Severance payments		(2,263	)		(2,247	)
Translation adjustments		(2,589	)		719
		147,673			152,779
Less: Cumulative contributions to severance insurance deposit accounts		(2,358	)		—
The National Pension Fund		(227	)		(255	)
Group severance insurance plan		(586	)		(635	)
Accrued severance benefits, net	$	144,502		$	151,889

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 has contributed a certain percentage of severance benefits, accrued for eligible employees for their services from January 1, 2018, to certain severance insurance deposit accounts. These accounts consist of time deposits and other guaranteed principal and interest, and are maintained at insurance companies, banks or security companies for the benefit of employees. The Company deducts the contributions made to 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 2019	$	578
2020		1,057
2021		1,522
2022		1,298
2023		1,743
2024		2,633
2025 – 2029		35,076

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.

Foreign Currency Gain (Loss), Net

3 Months Ended

Mar. 31, 2019

Foreign Currency [Abstract]

Foreign Currency Gain (Loss), Net

12. Foreign Currency Gain (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 our 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, 2019 and December 31, 2018, the outstanding intercompany loan balances including accrued interest between the Korean subsidiary and the Dutch subsidiary were $665,858 thousand and $666,597 thousand, respectively. The Korean won to U.S. dollar exchange rates were 1,137.8:1, 1,118.1:1 using the first base rate as of March 31, 2019 and December 31, 2018, respectively, as quoted by the KEB Hana Bank.

Income Taxes

3 Months Ended

Mar. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

The Company files income tax returns in the U.S., Korea, Japan, Taiwan and various other jurisdictions. The Company is subject to income- or non-income-based tax examinations by tax authorities of the U.S., Korea and multiple other foreign jurisdictions, where applicable, for all open tax years.

Income tax expenses recorded for three months ended March 31, 2019 and 2018 were $841 thousand and $

990

thousand, respectively, primarily attributable to interest on intercompany loan balances. The Company’s Korean subsidiary is the primary operating subsidiary of the Company. For the three months ended March 31, 2019, no income tax expense for the Korean subsidiary was recorded due to net operating loss carry-forwards available to offset taxable income and full allowance for deferred tax assets.

On December 22, 2017, H.R. 1, originally known as the Tax Cuts and Jobs Act, was enacted in the U.S. (the “Tax Reform Act”). The Tax Reform Act reduces the U.S. federal statutory rate to

21.0% from 35.0% effective January 1, 2018. The Tax Reform

Act

contains several key provisions, including global intangible low tax income and foreign derived intangible income provisions. For the year ended December 31, 2018, the Company analyzed the mandatory deemed repatriation tax and concluded that the Company has no tax liability on previously untaxed accumulated earnings and profits of its foreign subsidiaries. The Company also reviewed the other components of the Tax Reform

Act

and, based on its evaluation, no significant impact on the Company’s consolidated financial statements for the three months ended March 31, 2019.

Geographic and Segment Information

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Geographic and Segment Information

14. Geographic and Segment Information

The Company has two operating segments: its Foundry Services Group and Standard Products Group. The Company’s chief operating decision maker is its Chief Executive Officer, who allocates resources and assesses performance of the business and other activities based on gross profit.

The following sets forth information relating to the operating segment (in thousands):

	Three Months Ended
	March 31, 2019		March 31, 2018
Net Sales
Foundry Services Group	$	57,075	$	77,429
Standard Products Group
Display Solutions		58,230		49,696
Power Solutions		42,030		38,667
Total Standard Products Group	$	100,260	$	88,363
All other		45		27
Total net sales	$	157,380	$	165,819

	Three Months Ended
	March 31, 2019		March 31, 2018
Gross Profit
Foundry Services Group	$	3,637	$	20,664
Standard Products Group		19,020		24,039
All other		44		(122	)
Total gross profit	$	22,701	$	44,581

The Company’s revenue for Foundry Services Group is disaggregated depending on the timing of revenue recognition (in thousands):

	Three Months Ended March 31, 2019						Three Months Ended March 31, 2018
	Revenue recognized at the time of shipment or delivery		Revenue recognized over time		Total		Revenue recognized at the time of shipment or delivery		Revenue recognized over time		Total
Net Sales
Foundry Services Group	$	28,111	$	28,964	$	57,075	$	2,797	$	74,632	$	77,429

The following is a summary of net sales by geographic region, based on the location to which the products are billed (in thousands):

	Three Months Ended
	March 31, 2019		March 31, 2018
Korea	$	57,005	$	54,689
Asia Pacific (other than Korea)		84,164		89,706
U.S.A.		6,364		9,818
Europe		9,423		10,978
Others		424		628
Total	$	157,380	$	165,819

For the three months ended March 31, 2019 and 2018, of the Company’s net sales in Asia Pacific (other than Korea), net sales in Greater China (China, Hong Kong and Macau) represented 75.6% and 67.6%, respectively, and net sales in Taiwan represented 20.3% and 24.5%, respectively.

Net sales from the Company’s top ten largest customers accounted for 68% and 59% for the three months ended March 31, 2019 and 2018, respectively.

For the three months ended March 31, 2019, the Company had one customer that represented 28.7% of its net sales. For the three months ended March 31, 2018, the Company had two customers that represented 17.9% and 10.4% of its net sales.

98% of the Company’s property, plant and equipment are located in Korea as of March 31, 2019.

Accumulated Other Comprehensive Loss

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Accumulated Other Comprehensive Loss

15. Accumulated Other Comprehensive Loss

Accumulated other comprehensive loss consists of the following as of March 31, 2019 and December 31, 2018, respectively (in thousands):

	March 31, 2019			December 31, 2018
Foreign currency translation adjustments	$	(12,757	)	$	(20,061	)
Derivative adjustments		(361	)		(49	)
Total	$	(13,118	)	$	(20,110	)

Changes in accumulated other comprehensive loss for the three months ended March 31, 2019 and 2018 are as follows (in thousands):

Three Months Ended March 31, 2019	Foreign currency translation adjustments			Derivative adjustments			Total
Beginning balance	$	(20,061	)	$	(49	)	$	(20,110	)
Other comprehensive income (loss) before reclassifications		7,304			(499	)		6,805
Amounts reclassified from accumulated other comprehensive loss		—			187			187
Net current-period other comprehensive income (loss)		7,304			(312	)		6,992
Ending balance	$	(12,757	)	$	(361	)	$	(13,118	)

Three Months Ended March 31, 2018	Foreign currency translation adjustments			Derivative adjustments			Total
Beginning balance	$	(38,413	)	$	5,299		$	(33,114	)
Other comprehensive loss before reclassifications		(483	)		(67	)		(550	)
Amounts reclassified from accumulated other comprehensive income		—			(2,606	)		(2,606	)
Net current-period other comprehensive loss		(483	)		(2,673	)		(3,156	)
Ending balance	$	(38,896	)	$	2,626		$	(36,270	)

There was no income tax impact related to changes in accumulated other comprehensive loss for the three months ended March 31, 2019 and 2018 due to net operating loss carry-forwards available to offset taxable income and full allowance for deferred tax assets.

Earnings (Loss) per Share

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Earnings (Loss) per Share

16. Earnings (Loss) per Share

The following table illustrates the computation of basic and diluted earnings (loss) per common share for the three months ended March 31, 2019 and 2018:

	Three Months Ended
	March 31, 2019			March 31, 2018
	(In thousands of US dollars, except share data)
Basic Earnings (Loss) per Share
Net income (loss)	$	(34,125	)	$	2,763
Basic weighted average common stock outstanding		34,194,878			34,253,111
Basic earnings (loss) per share	$	(1.00	)	$	0.08
Diluted Earnings (Loss) per Share
Net income (loss)	$	(34,125	)	$	2,763
Basic weighted average common stock outstanding		34,194,878			34,253,111
Net effect of dilutive equity awards		—			901,582
Diluted weighted average common stock outstanding		34,194,878			35,154,693
Diluted earnings (loss) per share	$	(1.00	)	$	0.08

The following outstanding instruments were excluded from the computation of diluted earnings (loss) per share, as they have an anti-dilutive effect on the calculation:

	Three Months Ended
	March 31, 2019		March 31, 2018
Options		2,632,300		810,572
Restricted Stock Units		508,943		—

For the three months ended March 31, 2019 and 2018, 10,182,542 and 10,448,213,

respectively,

of potential common stock from the assumed conversion of Exchangeable Notes were excluded from the computation of diluted loss per share as the effect was anti-dilutive for the periods.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

17. Commitments and Contingencies

Long-term Purchase Agreements and Advances to Suppliers

The Company purchases raw materials from a variety of vendors. During the normal course of business, in order to manage manufacturing lead times and help assure adequacy supply, the Company from time to time may enter into multi-year purchase agreements, which specify future quantities and pricing of materials to be supplied by the vendors. The Company reviews the terms of the long-term supply agreements and assesses the need for any accrual for estimated losses, such as lower of cost or net realizable value that will not be recovered by future sales prices. No such accrual was required as of March 31, 2019 and December 31, 2018, respectively.

The Company, from time to time, may make prepayments to suppliers to procure materials to meet its planned production. The Company recorded prepayments of $

5,782

thousand and $

8,132

thousand as other current assets as of March 31, 2019 and December 31, 2018, respectively.

Subsequent Events

3 Months Ended

Mar. 31, 2019

Subsequent Events [Abstract]

Subsequent Events

18. Subsequent Events

Derivative contracts

In April 2019, the Company and NFIK entered into derivative contracts of zero cost collars for the period from July 2019 to December 2019. The total notional amounts are $60,000 thousand. In connection with these contracts, the Company paid $1,100 thousand of cash deposits to NFIK.

In April 2019, the Company and Deutsche Bank AG, Seoul Branch (“DB”) entered into derivative contracts of zero cost collars and forward for the period from April 2019 to December 2019. The total notional amounts for the zero cost collars and forward contracts were $30,000 thousand and $30,000 thousand, respectively. In connection with these contracts, the Company paid $4,600 thousand of cash deposits to DB.

Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Business

Basis of Presentation

“Interim

Reporting”

The December 31, 2018 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by US GAAP.

Leases

Revenue Recognition

fulfillment of performance obligations.

8,335

thousand as of December 31, 2017, $1,086 thousand was recognized as revenue during the three months ended March 31, 2018, respectively.

The Company provides

warranties

Substantially all of the Company’s contracts are one year or less in duration.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Inventories (Tables)

3 Months Ended

Mar. 31, 2019

Inventory Disclosure [Abstract]

Summary of Inventories

Inventories as of March 31, 2019 and December 31, 2018 consist of the following (in thousands):

	March 31, 2019			December 31, 2018
Finished goods	$	17,519		$	14,334
Semi-finished goods and work-in-process		49,191			39,135
Raw materials		22,145			21,150
Materials in-transit		690			1,890
Less: inventory reserve		(8,751	)		(4,898	)
Inventories, net	$	80,794		$	71,611

Changes in Inventory Reserve

Changes in inventory reserve for the three months ended March 31, 2019 and 2018 are as follows (in thousands):

	Three Months Ended
	March 31, 2019			March 31, 2018
Beginning balance	$	(4,898	)	$	(6,391	)
Change in reserve
Inventory reserve charged to costs of sales		(5,174	)		(1,620	)
Sale of previously reserved inventory		474			831
		(4,700	)		(789	)
Write off		664			2,530
Translation adjustments		183			(21	)
Ending balance	$	(8,751	)	$	(4,671	)

Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2019

Property, Plant and Equipment [Abstract]

Summary of Property, Plant and Equipment

Property, plant and equipment as of March 31, 2019 and December 31, 2018 are comprised of the following (in thousands):

	March 31, 2019			December 31, 2018
Buildings and related structures	$	69,539		$	70,665
Machinery and equipment		322,352			323,325
Finance lease right-of-use assets		2,500			—
Others		47,794			44,724
		442,185			438,714
Less: accumulated depreciation		(255,599	)		(251,962	)
Land		15,152			15,419
Property, plant and equipment, net	$	201,738		$	202,171

Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Summary of Intangible Assets

Intangible assets as of March 31, 2019 and December 31, 2018 are comprised of the following (in thousands):

	March 31, 2019
	Gross amount		Accumulated amortization			Net amount
Technology	$	19,015	$	(19,015	)	$	—
Customer relationships		27,310		(27,310	)		—
Intellectual property assets		11,601		(7,701	)		3,900
Intangible assets, net	$	57,926	$	(54,026	)	$	3,900

	December 31, 2018
	Gross amount		Accumulated amortization			Net amount
Technology	$	19,350	$	(19,350	)	$	—
Customer relationships		27,791		(27,791	)		—
Intellectual property assets		11,571		(7,618	)		3,953
Intangible assets, net	$	58,712	$	(54,759	)	$	3,953

Leases (Tables)

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Supplemental Balance Sheet Information Related To Leases [Table Text Block]

Supplemental balance sheet information related to leases is as follows (in thousands):

Leases	Classification	As of March 31, 2019
Assets
Operating lease	Operating lease right-of-use assets	$	13,046
Finance lease	Property, plant and equipment, net		2,422
Total leased assets		$	15,468
Liabilities
Current
Operating	Other current liabilities	$	2,072
Finance	Other current liabilities		242
Non-current
Operating	Non-current operating lease liabilities		10,975
Finance	Other non-current liabilities		2,199
Total lease liabilities		$	15,488

Lease, Cost [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, 2019
Operating lease cost	$	828
Finance lease cost
Amortization of right-of-use assets		78
Interest on lease liabilities		47
Total lease cost	$	953

Other Lease Information [Table Text Block]

Other lease information is as follows (in thousands):

	Three Months Ended
	March 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$	828
Operating cash flows from finance leases		47
Financing cash flows from finance leases		59
Weighted average remaining lease term
Operating leases		12.3 years
Finance leases		10.8 years
Weighted average discount rate
Operating leases		7.93	%
Finance leases		7.94	%

Schedule Of Future Minimum Lease Payments [Table Text Block]

The aggregate future lease payments for operating and finance leases as of March 31, 2019 are as follows (in thousands):

	Operating Leases			Finance Leases
2019	$	2,289		$	316
2020		2,705			421
2021		1,346			421
2022		1,113			421
2023		1,107			421
Thereafter		11,913			1,639
Total future lease payments		20,473			3,639
Less: Present value adjustment		(7,426	)		(1,198	)
Present value of future payments	$	13,047		$	2,441

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

As of December 31, 2018, the minimum aggregate rental payments due under non-cancelable operating lease contracts are as follows (in thousands):


2019	$	4,319
2020		3,569
2021		1,570
2022		1,319
2023		1,309
2024 and thereafter		13,978

	$	26,064

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2019

Payables and Accruals [Abstract]

Summary of Accrued Expenses

Accrued expenses as of March 31, 2019 and December 31, 2018 are comprised of the following (in thousands):

	March 31, 2019		December 31, 2018
Payroll, benefits and related taxes, excluding severance benefits	$	15,782	$	14,548
Withholding tax attributable to intercompany interest income		21,030		20,879
Interest on senior notes		3,444		8,226
Outside service fees		1,064		935
Others		2,161		1,662
Accrued expenses	$	43,481	$	46,250

Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Details of Derivative Contracts

Details of derivative contracts as of March 31, 2019 are as follows (in thousands):

Date of transaction	Type of derivative	Total notional amount		Month of settlement
June 27, 2018	Zero cost collar	$	9,000	April 2019 to June 2019
June 27, 2018	Forward	$	18,000	April 2019 to June 2019

Details of derivative contracts as of December 31, 2018 are as follows (in thousands):

Date of transaction	Type of derivative	Total notional amount		Month of settlement
June 27, 2018	Zero cost collar	$	18,000	January 2019 to June 2019
June 27, 2018	Forward	$	36,000	January 2019 to June 2019

Fair Values of Outstanding Zero Cost Collar and Forward Contracts Recorded as Assets and Liabilities

The fair values of the Company’s outstanding zero cost collar and forward contracts recorded as assets and liabilities as of March 31, 2019 and December 31, 2018 are as follows (in thousands):

Derivatives designated as hedging instruments:		March 31, 2019		December 31, 2018
Liability Derivatives:
Zero cost collars	Other current liabilities	$	67	$	117
Forward	Other current liabilities	$	654	$	607

Offsetting of Derivative Liabilities

Offsetting of derivative liabilities as of March 31, 2019 is as follows (in thousands):

As of March 31, 2019	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets		Net amounts of liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets					Net amount
As of March 31, 2019	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged			Net amount
Liability Derivatives:
Zero cost collars	$	67	$	—	$	67	$	—	$	(50	)	$	17
Forward	$	654	$	—	$	654	$	—	$	(210	)	$	444

Offsetting of derivative liabilities as of December 31, 2018 is as follows (in thousands):

As of December 31, 2018	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets		Net amounts of liabilities presented in the balance sheets		Gross amounts not offset in the balance sheets
As of December 31, 2018	Gross amounts of recognized liabilities		Gross amounts offset in the balance sheets				Financial instruments		Cash collateral pledged			Net amount
Liability Derivatives:
Zero cost collars	$	117	$	—	$	117	$	—	$	(360	)	$	(243	)
Forward	$	607	$	—	$	607	$	—	$	(1,450	)	$	(843	)

Impact of Derivative Instruments on Consolidated Statement of Operations

The following table summarizes the impact of derivative instruments on the consolidated statement of operations for the three months ended March 31, 2019 and 2018 (in thousands):

Derivatives in ASC 815 Cash Flow Hedging Relationships	Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)						Location /Amount of Gain (Loss) Reclassified from AOCI Into Statement of Operations (Effective Portion) (1)						Location /Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion) (1)
	Three Months Ended March 31,							Three Months Ended March 31,						Three Months Ended March 31,
	2019			2018				2019			2018			2019			2018
Zero cost collars	$	34		$	(132	)	Net sales	$	—		$	1,326	Other income, net	$	—		$	(71	)
Forwards	$	(533	)	$	65		Net sales	$	(89	)	$	1,280	Other income, net	$	(56	)	$	22
Forwards—excluded time value (1)	$	—		$	—		Net sales	$	(98	)	$	—	Other income, net	$	—		$	(27	)
	$	(499	)	$	(67	)		$	(187	)	$	2,606		$	(56	)	$	(76	)
							Total Revenue	$	157,380		$	165,819

(1)

The FASB issued the new guidance about hedging activities (ASU

2017

12)

2019

and the comparative prior period amounts were not restated and continued to be reported under the accounting standards in effect for such period.

- 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.

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+ Details

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

As of March 31, 2019, the following table represents the Company’s liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands):

	Carrying Value March 31, 2019		Fair Value Measurement March 31, 2019		Quoted Prices in Active Markets for Identical Asset (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Liabilities:
Derivative liabilities (other current liabilities)	$	721	$	721		—	$	721		—

As of December 31, 2018, the following table represents the Company’s liabilities measured at fair value on a recurring basis and the basis for that measurement (in thousands):

	Carrying Value December 31, 2018		Fair Value Measurement December 31, 2018		Quoted Prices in Active Markets for Identical Asset (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Liabilities:
Derivative liabilities (other current liabilities)	$	724	$	724		—	$	724		—

Schedule of Fair Value of Long-term Borrowings

Fair Value of Long-term Borrowings

	March 31, 2019				December 31, 2018
	Carrying Value		Fair Value		Carrying Value		Fair Value
	(In thousands of US dollars)
Long-term Borrowings:
5.0% Exchangeable Senior Notes due March 2021 (Level 2)	$	80,889	$	97,666	$	81,418	$	86,835
6.625% Senior Notes due July 2021 (Level 2)	$	222,126	$	213,038	$	222,159	$	202,046

- 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

Long-term Borrowings (Tables)

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Components of Long-term Borrowings

Long-term borrowings as of March 31, 2019 and December 31, 2018 are as follows (in thousands):

	March 31, 2019			December 31, 2018
5.0% Exchangeable Senior Notes due March 2021	$	83,740		$	84,660
6.625% Senior Notes due July 2021	$	224,250		$	224,500
Less: unamortized discount and debt issuance costs		(4,974	)		(5,583	)
Long-term borrowings, net of unamortized discount and debt issuance costs	$	303,016		$	303,577

- 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

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+ Details

Accrued Severance Benefits (Tables)

3 Months Ended

Mar. 31, 2019

Postemployment Benefits [Abstract]

Changes in Accrued Severance Benefits

Changes in accrued severance benefits are as follows (in thousands):

	Three Months Ended
	March 31, 2019			March 31, 2018
Beginning balance	$	149,408		$	149,795
Provisions		3,117			4,512
Severance payments		(2,263	)		(2,247	)
Translation adjustments		(2,589	)		719
		147,673			152,779
Less: Cumulative contributions to severance insurance deposit accounts		(2,358	)		—
The National Pension Fund		(227	)		(255	)
Group severance insurance plan		(586	)		(635	)
Accrued severance benefits, net	$	144,502		$	151,889

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 2019	$	578
2020		1,057
2021		1,522
2022		1,298
2023		1,743
2024		2,633
2025 – 2029		35,076

Geographic and Segment Information (Tables)

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Schedule of Operating Segments

The following sets forth information relating to the operating segment (in thousands):

	Three Months Ended
	March 31, 2019		March 31, 2018
Net Sales
Foundry Services Group	$	57,075	$	77,429
Standard Products Group
Display Solutions		58,230		49,696
Power Solutions		42,030		38,667
Total Standard Products Group	$	100,260	$	88,363
All other		45		27
Total net sales	$	157,380	$	165,819

	Three Months Ended
	March 31, 2019		March 31, 2018
Gross Profit
Foundry Services Group	$	3,637	$	20,664
Standard Products Group		19,020		24,039
All other		44		(122	)
Total gross profit	$	22,701	$	44,581

Disaggregation Of Revenue Recognition

The Company’s revenue for Foundry Services Group is disaggregated depending on the timing of revenue recognition (in thousands):

	Three Months Ended March 31, 2019						Three Months Ended March 31, 2018
	Revenue recognized at the time of shipment or delivery		Revenue recognized over time		Total		Revenue recognized at the time of shipment or delivery		Revenue recognized over time		Total
Net Sales
Foundry Services Group	$	28,111	$	28,964	$	57,075	$	2,797	$	74,632	$	77,429

Net Sales by Region, Based on Location of Products are Billed

The following is a summary of net sales by geographic region, based on the location to which the products are billed (in thousands):

	Three Months Ended
	March 31, 2019		March 31, 2018
Korea	$	57,005	$	54,689
Asia Pacific (other than Korea)		84,164		89,706
U.S.A.		6,364		9,818
Europe		9,423		10,978
Others		424		628
Total	$	157,380	$	165,819

Accumulated Other Comprehensive Loss (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Loss

Accumulated other comprehensive loss consists of the following as of March 31, 2019 and December 31, 2018, respectively (in thousands):

	March 31, 2019			December 31, 2018
Foreign currency translation adjustments	$	(12,757	)	$	(20,061	)
Derivative adjustments		(361	)		(49	)
Total	$	(13,118	)	$	(20,110	)

Changes in Accumulated Other Comprehensive Loss

Changes in accumulated other comprehensive loss for the three months ended March 31, 2019 and 2018 are as follows (in thousands):

Three Months Ended March 31, 2019	Foreign currency translation adjustments			Derivative adjustments			Total
Beginning balance	$	(20,061	)	$	(49	)	$	(20,110	)
Other comprehensive income (loss) before reclassifications		7,304			(499	)		6,805
Amounts reclassified from accumulated other comprehensive loss		—			187			187
Net current-period other comprehensive income (loss)		7,304			(312	)		6,992
Ending balance	$	(12,757	)	$	(361	)	$	(13,118	)

Three Months Ended March 31, 2018	Foreign currency translation adjustments			Derivative adjustments			Total
Beginning balance	$	(38,413	)	$	5,299		$	(33,114	)
Other comprehensive loss before reclassifications		(483	)		(67	)		(550	)
Amounts reclassified from accumulated other comprehensive income		—			(2,606	)		(2,606	)
Net current-period other comprehensive loss		(483	)		(2,673	)		(3,156	)
Ending balance	$	(38,896	)	$	2,626		$	(36,270	)

Earnings (Loss) per Share (Tables)

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Earnings (Loss) Per Common Share

The following table illustrates the computation of basic and diluted earnings (loss) per common share for the three months ended March 31, 2019 and 2018:

	Three Months Ended
	March 31, 2019			March 31, 2018
	(In thousands of US dollars, except share data)
Basic Earnings (Loss) per Share
Net income (loss)	$	(34,125	)	$	2,763
Basic weighted average common stock outstanding		34,194,878			34,253,111
Basic earnings (loss) per share	$	(1.00	)	$	0.08
Diluted Earnings (Loss) per Share
Net income (loss)	$	(34,125	)	$	2,763
Basic weighted average common stock outstanding		34,194,878			34,253,111
Net effect of dilutive equity awards		—			901,582
Diluted weighted average common stock outstanding		34,194,878			35,154,693
Diluted earnings (loss) per share	$	(1.00	)	$	0.08

Schedule of Antidilutive Securities Excluded from the Computation of Loss Per Common Share

The following outstanding instruments were excluded from the computation of diluted earnings (loss) per share, as they have an anti-dilutive effect on the calculation:

	Three Months Ended
	March 31, 2019		March 31, 2018
Options		2,632,300		810,572
Restricted Stock Units		508,943		—

Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) Segments BusinessLines	Mar. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segments	2
'Adjustment to increase the assets and liabilities		$ 8,484
Unbilled accounts receivable	$ 27,885			$ 38,181
Payment terms	The standard payment terms with customers are generally thirty to sixty days from the time of shipment, product delivery to the customer's location or customer acceptance, depending on the terms of the related arrangement.
Contract duration, description	Substantially all of the Company’s contracts are one year or less in duration.
Amounts billed to customers	$ 22,470
Deferred revenue	6,907			$ 6,477	$ 8,335
Deferred revenue recognized	$ 1,436	$ 1,086
Adjustments for New Accounting Pronouncement [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
'Adjustment to increase the assets and liabilities			$ 16,387
Minimum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Payment terms	30 days
Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Payment terms	60 days
Contract duration	1 year
Standard Products Group [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of business lines \| BusinessLines	2

Sales of Accounts Receivable and Receivable Discount Program - Additional Information (Detail) - Trade Accounts Receivable [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of accounts receivable	$ 7,989	$ 3,662
Selling, General and Administrative Expenses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pre-tax losses on accounts receivable	$ 25	$ 2

Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished goods	$ 17,519	$ 14,334
Semi-finished goods and work-in-process	49,191	39,135
Raw materials	22,145	21,150
Materials in-transit	690	1,890
Less: inventory reserve	(8,751)	(4,898)	$ (4,671)	$ (6,391)
Inventories, net	$ 80,794	$ 71,611

Inventories - Changes in Inventory Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Inventory Disclosure [Abstract]
Beginning balance	$ (4,898)	$ (6,391)
Change in reserve
Inventory reserve charged to costs of sales	(5,174)	(1,620)
Sale of previously reserved inventory	474	831
Change in reserve	(4,700)	(789)
Write off	664	2,530
Translation adjustments	183	(21)
Ending balance	$ (8,751)	$ (4,671)

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Jun. 29, 2018	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expenses		$ 8,087	$ 7,757
Water Treatment Facilities [Member]
Property, Plant and Equipment [Line Items]
Business acquisition, assets acquired and liabilities assumed, net	$ 4,172
Net proceeds from sale leaseback facility, financing activities	$ 4,172
Sale leaseback facility, financing activities, term	10 years
Business acquisition, other current liabilities	$ 553
Business acquisition, other non-current liabilities	$ 3,619

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 442,185	$ 438,714
Less: accumulated depreciation	(255,599)	(251,962)
Property, plant and equipment, net	201,738	202,171
Buildings and Related Structures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	69,539	70,665
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	322,352	323,325
Others [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	47,794	44,724
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	15,152	$ 15,419
Finance Lease Right Of Use Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,500

Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense for intangible assets	$ 216	$ 201

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	$ 57,926	$ 58,712
Accumulated amortization	(54,026)	(54,759)
Intangible asset, Net amount	3,900	3,953
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	19,015	19,350
Accumulated amortization	(19,015)	(19,350)
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	27,310	27,791
Accumulated amortization	(27,310)	(27,791)
Intellectual Property Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, Gross amount	11,601	11,571
Accumulated amortization	(7,701)	(7,618)
Intangible asset, Net amount	$ 3,900	$ 3,953

Leases - Additional Information (Detail)	3 Months Ended
Leases - Additional Information (Detail)	Mar. 31, 2019
Maximum [Member]
Lease Agreements Remaining Term of Lease	15 years
Lessee Lease Option To Extend	10 years
Minimum [Member]
Lease Agreements Remaining Term of Lease	1 year
Lessee Lease Option To Extend	1 year

Leases - Supplemental Balance Sheet (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Assets
Operating lease	$ 13,046
Total leased assets	15,468
Non-current
Operating	10,975
Total lease liabilities	15,488
Operating Lease Right Of Use Assets [Member]
Assets
Operating lease	13,046
Property, Plant and Equipment, Net [Member]
Assets
Finance lease	2,422
Other Current Liabilities [Member]
Current
Operating	2,072
Finance	242
Non CurrentOperating Lease Liabilities [Member]
Non-current
Operating	10,975
Other Noncurrent Liabilities [Member]
Non-current
Finance	$ 2,199

Leases - Components of lease cost (Detail) $ in Thousands	3 Months Ended
Leases - Components of lease cost (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 828
Finance lease cost [Abstract]
Amortization of right-of-use assets	78
Interest on lease liabilities	47
Total lease cost	$ 953

Leases - Other lease information (Detail) $ in Thousands	3 Months Ended
Leases - Other lease information (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Cash Paid For Amounts Included In Measurement Of Lease Liabilities [Abstract]
Operating cash flows from operating leases	$ 828
Operating cash flows from finance leases	47
Financing cash flows from finance leases	$ 59
Weighted Average Remaining Lease Term [Abstract]
Operating leases	12 years 3 months 18 days
Finance leases	10 years 9 months 18 days
Weighted Average Discount Rate [Abstract]
Operating leases	7.93%
Finance leases	7.94%

Leases - Aggregate future lease payment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating Leases, 2019	$ 2,289
Operating Leases, 2020	2,705	$ 3,569
Operating Leases, 2021	1,346	1,570
Operating Leases, 2022	1,113	1,319
Operating Leases, 2023	1,107	1,309
Operating Leases, Thereafter	11,913	13,978
Operating Leases, Total future lease payments	20,473	$ 26,064
Less: Present value adjustment	(7,426)
Present value of future payments	13,047
Finance Leases [Abstract]
Finance Leases, 2019	316
Finance Leases, 2020	421
Finance Leases, 2021	421
Finance Leases, 2022	421
Finance Leases, 2023	421
Finance Leases, Thereafter	1,639
Finance Leases, Total future lease payments	3,639
Less: Present value adjustment	(1,198)
Present value of future payments	$ 2,441

Leases - Minimum aggregate rental payments due (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
2019		$ 4,319
2020	$ 2,705	3,569
2021	1,346	1,570
2022	1,113	1,319
2023	1,107	1,309
2024 and thereafter	11,913	13,978
Operating Leases, Total future lease payments	$ 20,473	$ 26,064

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Payroll, benefits and related taxes, excluding severance benefits	$ 15,782	$ 14,548
Withholding tax attributable to intercompany interest income	21,030	20,879
Interest on senior notes	3,444	8,226
Outside service fees	1,064	935
Others	2,161	1,662
Accrued expenses	$ 43,481	$ 46,250

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Estimated amount reclassified from accumulated other comprehensive income into income, period	12 months
Estimated amount reclassified from accumulated other comprehensive income into income	$ 361
Zero Cost Collar and Forward Contracts [Member] \| Nomura Financial Investment (Korea) Co., Ltd. [Member]
Derivative [Line Items]
Deposit with counterparty	3,300	$ 4,000
Threshold amount of cash collateral	500
Cash collateral for credit exposure in derivatives	260	$ 1,810
Termination provisions for cash and cash equivalents	$ 30,000

Derivative Financial Instruments - Details of Derivative Contracts (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Zero Cost Collar One [Member]
Derivative [Line Items]
Date of transaction	Jun. 27, 2018	Jun. 27, 2018
Type of derivative	Zero cost collar	Zero cost collar
Total notional amount	$ 9,000	$ 18,000
Month of settlement, start	2019-04	2019-01
Month of settlement, end	2019-06	2019-06
Forward [Member]
Derivative [Line Items]
Date of transaction	Jun. 27, 2018	Jun. 27, 2018
Type of derivative	Forward	Forward
Total notional amount	$ 18,000	$ 36,000
Month of settlement, start	2019-04	2019-01
Month of settlement, end	2019-06	2019-06

Derivative Financial Instruments - Fair Values of Outstanding Zero Cost Collar and Forward Contracts Recorded as Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Zero Cost Collars [Member]
Liability Derivatives:
Other current liabilities	$ 67	$ 117
Forward [Member]
Liability Derivatives:
Other current liabilities	654	607
Other Current Liabilities [Member] \| Zero Cost Collars [Member]
Liability Derivatives:
Other current liabilities	67	117
Other Current Liabilities [Member] \| Forward [Member]
Liability Derivatives:
Other current liabilities	$ 654	$ 607

Derivative Financial Instruments - Offsetting of Derivative Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Zero Cost Collars [Member]
Derivative [Line Items]
Liability Derivatives, Gross amounts of recognized liabilities	$ 67	$ 117
Liability Derivatives, Gross amounts offset in the balance sheets	0	0
Liability Derivatives, Net amounts of liabilities presented in the balance sheets	67	117
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	(50)	(360)
Liability Derivatives, Net amount after master netting	17	(243)
Foreign Exchange Forward [Member]
Derivative [Line Items]
Liability Derivatives, Gross amounts of recognized liabilities	654	607
Liability Derivatives, Gross amounts offset in the balance sheets	0	0
Liability Derivatives, Net amounts of liabilities presented in the balance sheets	654	607
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	(210)	(1,450)
Liability Derivatives, Net amount after master netting	$ 444	$ (843)

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, 2019	Mar. 31, 2018
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ (499)	$ (67)
Total Revenue	157,380	165,819
Other Income, Net [Member]
Derivative [Line Items]
Amount of Gain (loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(56)	(76)
Net Sales [Member]
Derivative [Line Items]
Amount of Gain (loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	(187)	2,606
Zero Cost Collars [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	34	(132)
Zero Cost Collars [Member] \| Other Income, Net [Member]
Derivative [Line Items]
Amount of Gain (loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	0	(71)
Zero Cost Collars [Member] \| Net Sales [Member]
Derivative [Line Items]
Amount of Gain (loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	0	1,326
Forward [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	(533)	65
Forward [Member] \| Other Income, Net [Member]
Derivative [Line Items]
Amount of Gain (loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(56)	22
Forward [Member] \| Net Sales [Member]
Derivative [Line Items]
Amount of Gain (loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	(89)	1,280
Forwards - excluded time value [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	0	0
Forwards - excluded time value [Member] \| Other Income, Net [Member]
Derivative [Line Items]
Amount of Gain (loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	0	(27)
Forwards - excluded time value [Member] \| Net Sales [Member]
Derivative [Line Items]
Amount of Gain (loss) Reclassified from AOCI into Statement of Operations (Effective Portion)	$ (98)	$ 0

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended	12 Months Ended
	Jan. 17, 2017	Jul. 18, 2013	Mar. 31, 2019	Dec. 31, 2018	Feb. 28, 2019	Jan. 31, 2019
6.625% Senior Notes Due 2021 [Member] \| Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate		6.625%	6.625%	6.625%
Due date		Jul. 15, 2021	Jul. 01, 2021	Jul. 01, 2021
Aggregate principal amount		$ 225,000
Debt issuance costs paid		5,000
Original debt issue discount		$ 1,100
Principal Repurchase Amount Of Exchangeable Notes				$ 500		$ 250
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				$ 1,590	$ 920
Other Asset Class [Member] \| Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value on non-recurring basis			0	0
Liabilities fair value on non-recurring basis			$ 0	$ 0

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - Other Current Liabilities [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Carrying Value [Member]
Liabilities:
Derivative liabilities	$ 721	$ 724
Estimate of Fair Value Measurement [Member]
Liabilities:
Derivative liabilities	721	724
Significant Other Observable Inputs (Level 2) [Member]
Liabilities:
Derivative liabilities	$ 721	$ 724

Fair Value Measurements - Schedule of Fair Value of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Long-term Borrowings:
Carrying amount of senior notes	$ 303,016	$ 303,577
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	80,889	81,418
Estimated fair value of senior notes	97,666	86,835
6.625% Senior Notes Due 2021 [Member] \| Senior Notes [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Long-term Borrowings:
Carrying amount of senior notes	222,126	222,159
Estimated fair value of senior notes	$ 213,038	$ 202,046

Fair Value Measurements - Schedule of Fair Value of Long-term Borrowings (Parenthetical) (Detail)			3 Months Ended	12 Months Ended
	Jan. 17, 2017	Jul. 18, 2013	Mar. 31, 2019	Dec. 31, 2018
5.0% Exchangeable Senior Notes due March 2021 [Member] \| Exchangeable Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.00%		5.00%	5.00%
Due date	Mar. 01, 2021		Mar. 01, 2021	Mar. 01, 2021
6.625% Senior Notes Due 2021 [Member] \| Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate		6.625%	6.625%	6.625%
Due date		Jul. 15, 2021	Jul. 01, 2021	Jul. 01, 2021

Long-Term Borrowings - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 17, 2017	Jan. 17, 2017	Jul. 18, 2013	Feb. 28, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2019
Debt Instrument [Line Items]
Repurchase of common stock, shares								1,795,444
Repurchase of common stock					$ 2,585			$ 11,401
Loss on early extinguishment of long-term borrowings, net					$ (42)
6.625% Senior Notes Due 2021 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount			$ 225,000
Interest rate			6.625%		6.625%		6.625%
Due date			Jul. 15, 2021		Jul. 01, 2021		Jul. 01, 2021
Aggregate principal amount of senior notes pricing			99.50%
Debt issuance costs paid			$ 5,000
Interest expense related to the Exchangeable Notes					$ 3,930	$ 3,926
Original debt issue discount			$ 1,100
Debt Instrument, Repurchased Face Amount							$ 500		$ 250
Loss on early extinguishment of long-term borrowings, net							$ 28
6.625% Senior Notes Due 2021 [Member] \| Senior Notes [Member] \| 2018 [Member]
Debt Instrument [Line Items]
Redemption price plus accrued, unpaid interest and special interest to the date of redemption							101.656%
6.625% Senior Notes Due 2021 [Member] \| Senior Notes [Member] \| 2019 [Member]
Debt Instrument [Line Items]
Redemption price plus accrued, unpaid interest and special interest to the date of redemption							100.00%
5.0% Exchangeable Senior Notes due March 2021 [Member] \| Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 86,250	$ 86,250
Interest rate	5.00%	5.00%			5.00%		5.00%
Due date		Mar. 01, 2021			Mar. 01, 2021		Mar. 01, 2021
Aggregate principal amount of senior notes pricing	5.00%
Convertible notes principal amount denomination value					$ 1,000
Conversion of converted notes, shares issued					121.1387
Exchange price					$ 8.26
Redemption price plus accrued, unpaid interest and special interest to the date of redemption					100.00%
Minimum required percentage of holders to declare repurchase of notes					25.00%
Percentage of notes to repurchased on declaration by minimum required holders					100.00%
Debt issuance costs paid		$ 5,902			$ 5,902
Interest expense related to the Exchangeable Notes					$ 1,408		$ 1,411
Debt Instrument, Repurchased Face Amount				$ 920			1,590
Loss on early extinguishment of long-term borrowings, net				$ 63			$ 234

Long-term Borrowings - Components of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Less: unamortized discount and debt issuance costs	$ (4,974)	$ (5,583)
Long-term borrowings, net of unamortized discount and debt issuance costs	303,016	303,577
Exchangeable Senior Notes [Member] \| 5.0% Exchangeable Senior Notes due March 2021 [Member]
Debt Instrument [Line Items]
Long-term borrowings	83,740	84,660
Senior Notes [Member] \| 6.625% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term borrowings	$ 224,250	$ 224,500

Long-term Borrowings - Components of Long-term Borrowings (Parenthetical) (Detail)			3 Months Ended	12 Months Ended
	Jan. 17, 2017	Jul. 18, 2013	Mar. 31, 2019	Dec. 31, 2018
5.0% Exchangeable Senior Notes due March 2021 [Member] \| Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate	5.00%		5.00%	5.00%
Due date	Mar. 01, 2021		Mar. 01, 2021	Mar. 01, 2021
6.625% Senior Notes Due July 2021 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Interest rate		6.625%	6.625%	6.625%
Due date		Jul. 15, 2021	Jul. 01, 2021	Jul. 01, 2021

Accrued Severance Benefits - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019
Percentage of employees eligible for severance benefits	98.00%
Korea [Member] \| Maximum [Member]
Retirement age of employees	60 days

Accrued Severance Benefits - Changes in Accrued Severance Benefits (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Postemployment Benefits [Abstract]
Beginning balance	$ 149,408	$ 149,795
Provisions	3,117	4,512
Severance payments	(2,263)	(2,247)
Translation adjustments	(2,589)	719
Ending balance	147,673	152,779
Less: Cumulative contributions to severance insurance deposit accounts	(2,358)	0
The National Pension Fund	(227)	(255)
Group severance insurance plan	(586)	(635)
Accrued severance benefits, net	$ 144,502	$ 151,889	$ 146,031

Accrued Severance Benefits - Future Benefits Payments to Employees (Detail) $ in Thousands	Mar. 31, 2019 USD ($)
Retirement Benefits [Abstract]
Remainder of 2019	$ 578
2020	1,057
2021	1,522
2022	1,298
2023	1,743
2024	2,633
2025 - 2029	$ 35,076

Foreign Currency Gain (Loss), Net - Additional Information (Detail) $ in Thousands	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Foreign Currency Transaction [Abstract]
Exchange rates using first base rate	1,137.8	1,118.1
Intercompany loan balances	$ 665,858	$ 666,597

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Income tax expenses (benefits)	$ 841	$ 990
Statutory income tax rate	21.00%		35.00%
Korean Subsidiary [Member]
Income Tax Contingency [Line Items]
Income tax expenses (benefits)	$ 0

Geographic and Segment Information - Additional Information (Detail) - Segments	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments \| Segments	2
Customer Concentration Risk [Member] \| Net Sales [Member] \| Top Ten Customers [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	68.00%	59.00%
Customer Concentration Risk [Member] \| Net Sales [Member] \| Top Customer One [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	28.70%	17.90%
Customer Concentration Risk [Member] \| Net Sales [Member] \| Top Customer Two [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage		10.40%
Geographic Concentration Risk [Member] \| Net Sales [Member] \| Asia Pacific Other Than Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	75.60%
Geographic Concentration Risk [Member] \| Net Sales [Member] \| Taiwan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	20.30%	24.50%
Geographic Concentration Risk [Member] \| Net Sales [Member] \| CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage		67.60%
Geographic Concentration Risk [Member] \| Property, Plant and Equipment [Member] \| Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	98.00%

Geographic and Segment Information - Schedule of Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total net sales	$ 157,380	$ 165,819
Total gross profit	22,701	44,581
Foundry Services Group [Member]
Segment Reporting Information [Line Items]
Total net sales	57,075	77,429
Operating Segments [Member] \| Foundry Services Group [Member]
Segment Reporting Information [Line Items]
Total net sales	57,075	77,429
Total gross profit	3,637	20,664
Operating Segments [Member] \| Standard Products Group [Member]
Segment Reporting Information [Line Items]
Total net sales	100,260	88,363
Total gross profit	19,020	24,039
Operating Segments [Member] \| Standard Products Group [Member] \| Display Solutions [Member]
Segment Reporting Information [Line Items]
Total net sales	58,230	49,696
Operating Segments [Member] \| Standard Products Group [Member] \| Power Solutions [Member]
Segment Reporting Information [Line Items]
Total net sales	42,030	38,667
All Other [Member]
Segment Reporting Information [Line Items]
Total net sales	45	27
Total gross profit	$ 44	$ (122)

Geographic and Segment Information - Summary of Revenue Disaggregated Depending on Timing of Revenue Recognition (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Foundry Services Group	$ 157,380	$ 165,819
Foundry Services Group [Member]
Disaggregation of Revenue [Line Items]
Foundry Services Group	57,075	77,429
Revenue Recognized At The Time Of Shipment Or Delivery [Member] \| Foundry Services Group [Member]
Disaggregation of Revenue [Line Items]
Foundry Services Group	28,111	2,797
Revenue Recognized Over Time [Member] \| Foundry Services Group [Member]
Disaggregation of Revenue [Line Items]
Foundry Services Group	$ 28,964	$ 74,632

Geographic and Segment Information - Net Sales by Region, Based on Location of Products are Billed (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	$ 157,380	$ 165,819
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	57,005	54,689
Asia Pacific (Other Than Korea) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	84,164	89,706
U.S.A. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	6,364	9,818
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	9,423	10,978
Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales	$ 424	$ 628

Accumulated Other Comprehensive Loss - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Income tax related to accumulated other comprehensive loss	$ 0	$ 0

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Foreign currency translation adjustments	$ (12,757)	$ (20,061)
Derivative adjustments	(361)	(49)
Total	$ (13,118)	$ (20,110)

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Income Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	$ (17,310)	$ (39,637)
Total other comprehensive income (loss)	6,992	(3,156)
Balance ending	(46,311)	(29,934)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	(20,061)	(38,413)
Other comprehensive income (loss) before reclassifications	7,304	(483)
Total other comprehensive income (loss)	7,304	(483)
Balance ending	(12,757)	(38,896)
Derivative Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	(49)	5,299
Other comprehensive income (loss) before reclassifications	(499)	(67)
Amounts reclassified from accumulated other comprehensive loss	187	(2,606)
Total other comprehensive income (loss)	(312)	(2,673)
Balance ending	(361)	2,626
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning	(20,110)	(33,114)
Other comprehensive income (loss) before reclassifications	6,805	(550)
Amounts reclassified from accumulated other comprehensive loss	187	(2,606)
Total other comprehensive income (loss)	6,992	(3,156)
Balance ending	$ (13,118)	$ (36,270)

Earnings (Loss) per Share - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Conversion Of Exchangeable Notes	10,182,542	10,448,213

Earnings (Loss) per Share - Schedule of Computation of Basic and Diluted Earnings (Loss) Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income (loss)	$ (34,125)	$ 2,763
Basic weighted average common stock outstanding	34,194,878	34,253,111
Basic earnings (loss) per share	$ (1.00)	$ 0.08
Diluted Earnings per Share
Net income (loss)	$ (34,125)	$ 2,763
Basic weighted average common stock outstanding	34,194,878	34,253,111
Net effect of dilutive equity awards		901,582
Diluted weighted average common stock outstanding	34,194,878	35,154,693
Diluted earnings (loss) per share	$ (1.00)	$ 0.08

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

- Definition

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

+ References + Details

Earnings (Loss) per Share - Schedule of Antidilutive Securities Excluded from the Computation of Loss Per Common Share (Detail) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding units and warrants excluded from computation of diluted loss per share/unit	10,182,542	10,448,213
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	2,632,300	810,572
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding units and warrants excluded from computation of diluted loss per share/unit	508,943

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Other Current Assets [Member]
Loss Contingencies [Line Items]
Prepayments to suppliers	$ 5,782	$ 8,132

Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] $ in Thousands	Apr. 01, 2019 USD ($)
Nomura Financial Investment Co Ltd [Member]
Derivative, Notional Amount	$ 60,000
Margin Deposit Assets	1,100
Deutsche Bank AG, Seoul Branch [Member]
Derivative, Notional Amount	60,000
Margin Deposit Assets	$ 4,600