Amkor Technology (AMKR) 10-Q 30 Apr 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 24, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	000-29472
Entity Registrant Name	AMKOR TECHNOLOGY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-1722724
Entity Address, Address Line One	2045 East Innovation Circle
Entity Address, City or Town	Tempe
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85284
City Area Code	480
Local Phone Number	821-5000
Entity Filer Category	Large Accelerated Filer
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	AMKR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		241,149,312
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001047127

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 1,152,616	$ 894,964
Cost of sales	963,708	774,203
Gross profit	188,908	120,761
Selling, general and administrative	72,582	71,587
Research and development	32,253	35,754
Total operating expenses	104,835	107,341
Operating income	84,073	13,420
Interest expense	17,045	19,273
Other (income) expense, net	(2,315)	(4,565)
Total other expense, net	14,730	14,708
Income (loss) before taxes	69,343	(1,288)
Income tax expense	4,846	21,380
Net income (loss)	64,497	(22,668)
Net income attributable to non-controlling interests	(608)	(211)
Net income (loss) attributable to Amkor	$ 63,889	$ (22,879)
Net income (loss) attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.27	$ (0.10)
Diluted (in dollars per share)	$ 0.26	$ (0.10)
Shares used in computing per common share amounts:
Basic (in shares)	240,919	239,414
Diluted (in shares)	241,333	239,414

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 64,497	$ (22,668)
Other comprehensive income (loss), net of tax:
Adjustments to net unrealized gains (losses) on available-for-sale debt investments	108	0
Adjustments to unrealized components of defined benefit pension plans	11	(132)
Foreign currency translation	475	(2,224)
Total other comprehensive income (loss)	594	(2,356)
Comprehensive income (loss)	65,091	(25,024)
Comprehensive income attributable to non-controlling interests	(608)	(211)
Comprehensive income (loss) attributable to Amkor	$ 64,483	$ (25,235)

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 941,447	$ 894,948
Restricted cash	610	610
Short-term investments (amortized cost of $58,139 in 2020)	58,263	6,348
Accounts receivable, net of allowances	880,629	850,753
Inventories	238,201	220,602
Other current assets	34,553	28,272
Total current assets	2,153,703	2,001,533
Property, plant and equipment, net	2,367,746	2,404,850
Operating lease right of use assets	147,985	148,549
Goodwill	26,235	25,976
Restricted cash	3,267	2,974
Other assets	112,701	111,733
Total assets	4,811,637	4,695,615
Current liabilities:
Short-term borrowings and current portion of long-term debt	141,521	144,479
Trade accounts payable	562,633	571,054
Capital expenditures payable	107,131	77,044
Accrued expenses	236,464	267,226
Total current liabilities	1,047,749	1,059,803
Long-term debt	1,371,501	1,305,755
Pension and severance obligations	178,084	176,971
Long-term operating lease liabilities	89,733	91,107
Other non-current liabilities	65,945	71,740
Total liabilities	2,753,012	2,705,376
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized, designated Series A, none issued	0	0
Common stock, $0.001 par value, 500,000 shares authorized; 287,093 and 286,877 shares issued; and 241,016 and 240,805 shares outstanding in 2020 and 2019, respectively	287	287
Additional paid-in capital	1,931,088	1,927,739
Retained earnings	297,966	234,077
Accumulated other comprehensive income (loss)	19,709	19,115
Treasury stock, at cost, 46,077 and 46,072 shares, in 2020 and 2019, respectively	(217,533)	(217,479)
Total Amkor stockholders’ equity	2,031,517	1,963,739
Non-controlling interests in subsidiaries	27,108	26,500
Total equity	2,058,625	1,990,239
Total liabilities and equity	$ 4,811,637	$ 4,695,615

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Short term investments amortized cost	$ 58,139
Stockholders’ equity:
Preferred stock designated Series A, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock designated Series A, shares authorized	10,000,000	10,000,000
Preferred stock designated Series A, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	287,093,000	286,877,000
Common stock, shares outstanding	241,016,000	240,805,000
Treasury stock, shares	46,077,000	46,072,000

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Total Amkor Stockholders' Equity	Common Stock	Additional Paid- In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest in Subsidiaries
Balance at beginning of period, shares at Dec. 31, 2018			285,352
Balance at beginning of period, shares at Dec. 31, 2018							(45,967)
Balance at beginning of period at Dec. 31, 2018	$ 1,855,900	$ 1,830,540	$ 285	$ 1,909,425	$ 113,189	$ 23,812	$ (216,171)	$ 25,360
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(22,668)	(22,879)			(22,879)			211
Other comprehensive income (loss)	(2,356)	(2,356)				(2,356)
Treasury stock acquired through surrender of shares for tax withholding, shares							(5)
Treasury stock acquired through surrender of shares for tax withholding	(48)	(48)					$ (48)
Issuance of stock through share-based compensation plans, shares			78
Issuance of stock through share-based compensation plans	286	286	$ 0	286
Share-based compensation	1,468	1,468		1,468
Balance at end of period, shares at Mar. 31, 2019			285,430
Balance at end of period, shares at Mar. 31, 2019							(45,972)
Balance at end of period at Mar. 31, 2019	$ 1,832,582	1,807,011	$ 285	1,911,179	90,310	21,456	$ (216,219)	25,571
Balance at beginning of period, shares at Dec. 31, 2019	286,877		286,877
Balance at beginning of period, shares at Dec. 31, 2019	(46,072)						(46,072)
Balance at beginning of period at Dec. 31, 2019	$ 1,990,239	1,963,739	$ 287	1,927,739	234,077	19,115	$ (217,479)	26,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	64,497	63,889			63,889			608
Other comprehensive income (loss)	594	594				594
Treasury stock acquired through surrender of shares for tax withholding, shares							(5)
Treasury stock acquired through surrender of shares for tax withholding	(54)	(54)					$ (54)
Issuance of stock through share-based compensation plans, shares			216
Issuance of stock through share-based compensation plans	1,519	1,519		1,519
Share-based compensation	$ 1,830	1,830		1,830
Balance at end of period, shares at Mar. 31, 2020	287,093		287,093
Balance at end of period, shares at Mar. 31, 2020	(46,077)						(46,077)
Balance at end of period at Mar. 31, 2020	$ 2,058,625	$ 2,031,517	$ 287	$ 1,931,088	$ 297,966	$ 19,709	$ (217,533)	$ 27,108

Condensed Consolidated Statemen

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 64,497	$ (22,668)
Depreciation and amortization	123,657	135,835
Other operating activities and non-cash items	8,287	15,928
Changes in assets and liabilities	(99,852)	(77,038)
Net cash provided by operating activities	96,589	52,057
Cash flows from investing activities:
Payments for property, plant and equipment	(55,888)	(203,216)
Proceeds from sale of property, plant and equipment	1,887	180
Proceeds from insurance recovery for property, plant and equipment	0	1,538
Payments for short-term investments	(55,754)	0
Other investing activities	5,163	(569)
Net cash used in investing activities	(104,592)	(202,067)
Cash flows from financing activities:
Proceeds from revolving credit facilities	201,000	0
Proceeds from short-term debt	14,086	29,781
Payments of short-term debt	(9,409)	(10,588)
Proceeds from issuance of long-term debt	24,000	572,375
Payments of long-term debt	(172,336)	(63,636)
Payments of finance lease obligations	(2,355)	(1,376)
Other financing activities	109	(2,848)
Net cash provided by financing activities	55,095	523,708
Effect of exchange rate fluctuations on cash, cash equivalents and restricted cash	(300)	(829)
Net increase in cash, cash equivalents and restricted cash	46,792	372,869
Cash, cash equivalents and restricted cash, beginning of period	898,532	688,051
Cash, cash equivalents and restricted cash, end of period	945,324	1,060,920
Non-cash investing and financing activities:
Property, plant and equipment included in capital expenditures payable	$ 107,344	$ 124,547

Interim Financial Statements

Interim Financial Statements	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interim Financial Statements	Interim Financial Statements Basis of Presentation. The Consolidated Financial Statements and related disclosures as of March 31, 2020 , and for the three months ended March 31, 2020 and 2019 , are unaudited, pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The December 31, 2019 Consolidated Balance Sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. In our opinion, these financial statements include all adjustments (consisting only of normal recurring adjustments) necessary for the fair statement of the results for the interim periods. These financial statements should be read in conjunction with the financial statements included in our Annual Report for the year ended December 31, 2019 , filed on Form 10-K with the SEC on February 19, 2020. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results to be expected for the full year. Unless the context otherwise requires, all references to “Amkor,” “we,” “us,” “our” or the “company” are to Amkor Technology, Inc. and our subsidiaries. Certain prior year amounts have been reclassified to conform to current year presentation. Use of Estimates. The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments, including the impact of Covid-19 and any worsening of the global business and economic environment. Goodwill. The balance of goodwill in our Consolidated Balance Sheets reflects adjustments for foreign currency translation. Unbilled Receivables . Total unbilled receivables as of March 31, 2020 and December 31, 2019 were $131.3 million and $125.4 million , respectively.

Net Sales by Product Group and

Net Sales by Product Group and End Market	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Net Sales by Product Group and End Market	Net Sales by Product Group and End Market Net sales by product group consist of the following: For the Three Months Ended March 31, 2020 2019 (In thousands) Advanced products (1) $ 705,158 $ 422,446 Mainstream products (2) 447,458 472,518 Total net sales $ 1,152,616 $ 894,964 (1) Advanced products include flip chip and wafer-level processing and related test services. (2) Mainstream products include wirebond packaging and related test services. Net sales by end market consist of the following : For the Three Months Ended March 31, 2020 2019 Communications (handheld devices, smartphones, tablets) 38 % 38 % Consumer (connected home, set-top boxes, televisions, visual imaging, wearables) 24 % 14 % Automotive, industrial and other (driver assist, infotainment, performance, safety) 23 % 28 % Computing (datacenter, infrastructure, PC/laptop, storage) 15 % 20 % Total net sales 100 % 100 %

Other Income and Expense

Other Income and Expense	3 Months Ended
	Mar. 31, 2020
Other Income and Expenses [Abstract]
Other Income and Expense	Other Income and Expense Other income and expense consists of the following: For the Three Months Ended March 31, 2020 2019 (In thousands) Interest income $ (2,258 ) $ (2,064 ) Foreign currency (gain) loss, net (229 ) (2,013 ) Loss on debt retirement 428 — Other (256 ) (488 ) Other (income) expense, net $ (2,315 ) $ (4,565 )

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense of $4.8 million for the three months ended March 31, 2020 reflects income taxes, foreign withholding taxes and minimum taxes. ASC 740 generally requires we provide for income taxes during interim periods based on the estimated annual effective tax rate (“AETR”) for the full year. For the three months ended March 31, 2020, we have excluded a jurisdiction from the AETR calculation and used a discrete method to calculate the income tax provision for that jurisdiction. We believe inclusion of this jurisdiction in the AETR calculation is impractical at this time given that normal deviations in the projected pre-tax net income (loss) would result in a disproportionate and unreliable annual effective tax rate under the AETR method. We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and results of recent operations. We maintain a valuation allowance on certain U.S. and foreign deferred tax assets. Such valuation allowances are released as the related tax benefits are realized or when sufficient evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized. Unrecognized tax benefits represent reserves for potential tax deficiencies or reductions in tax benefits that could result from federal, state or foreign tax audits. Gross unrecognized tax benefits decreased from $26.2 million at December 31, 2019 to $23.1 million as of March 31, 2020 , primarily due to the lapse of statutes of limitations in foreign jurisdictions. All of our unrecognized tax benefits would reduce our effective tax rate if recognized. Our unrecognized tax benefits are subject to change for effective settlement of examinations, changes in the recognition threshold of tax positions, the expiration of statutes of limitations and other factors. We have tax returns that are open to examination in various jurisdictions for tax years 2012-2019. The open years contain matters that could be subject to differing interpretations of applicable tax laws and regulations related to the amount and/or timing of income, deductions and tax credits. There can be no assurance that the outcome of the examinations will be favorable.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income attributable to Amkor common stockholders by the weighted-average number of common shares outstanding during the period. The weighted-average number of common shares outstanding is reduced for treasury stock. Diluted EPS is computed based on the weighted-average number of common shares outstanding plus the effect of dilutive potential common shares outstanding during the period. Dilutive potential common shares include outstanding stock options and unvested restricted shares. The following table summarizes the computation of basic and diluted EPS: For the Three Months Ended March 31, 2020 2019 (In thousands, except per share data) Net income (loss) attributable to Amkor common stockholders $ 63,889 $ (22,879 ) Weighted-average number of common shares outstanding - basic 240,919 239,414 Effect of dilutive securities: Stock options and restricted share awards 414 — Weighted-average number of common shares outstanding - diluted 241,333 239,414 Net income (loss) attributable to Amkor per common share: Basic $ 0.27 $ (0.10 ) Diluted 0.26 (0.10 ) The following table summarizes the potential shares of common stock that were excluded from diluted EPS because the effect of including these potential shares was anti-dilutive: For the Three Months Ended March 31, 2020 2019 (In thousands) Stock options and restricted share awards 4,321 7,123

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Changes in accumulated other comprehensive income (loss), net of tax, consist of the following: Unrealized Gains (Losses) on Available-for-Sale Debt Investments Defined Benefit Pension (1) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2019 $ — $ (4,820 ) $ 23,935 $ 19,115 Other comprehensive income (loss) before reclassifications 108 — 475 583 Amounts reclassified from accumulated other comprehensive income (loss) — 11 — 11 Other comprehensive income (loss) 108 11 475 594 Accumulated other comprehensive income (loss) at March 31, 2020 $ 108 $ (4,809 ) $ 24,410 $ 19,709 Defined Benefit Pension (1) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2018 $ 2,659 $ 21,153 $ 23,812 Other comprehensive income (loss) before reclassifications — (2,224 ) $ (2,224 ) Amounts reclassified from accumulated other comprehensive income (loss) (132 ) — $ (132 ) Other comprehensive income (loss) (132 ) (2,224 ) (2,356 ) Accumulated other comprehensive income (loss) at March 31, 2019 $ 2,527 $ 18,929 $ 21,456 (1) Amounts reclassified out of accumulated other comprehensive income (loss) are included as a component of net periodic pension cost ( Note 12 ) or other (income) expense, net.

Investments

Investments	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Investments	Investments We classify our short-term investments in fixed income securities as available-for-sale debt investments, except for one foreign government security classified as held-to-maturity. The held-to-maturity debt security matured in the first quarter ended March 31, 2020 . All of our available-for-sale debt investments as of March 31, 2020 will be available to fund current operations and are recorded at fair value ( Note 13 ). Unrealized gains and losses on our available-for-sale debt investments are included as a separate component of accumulated other comprehensive income (loss), net of tax. Realized gains and losses on our available-for-sale debt investments and declines in value judged to be an impairment are included in other (income) expense, net. The cost of short-term investments matured or sold is based on the average cost method. In determining if and when a decline in value below the adjusted cost of our available-for-sale debt investments is an impairment, we evaluate on an ongoing basis the market conditions, trends of earnings, financial condition, credit ratings, any underlying collateral and other key measures for our short-term investments. An impairment is considered if (i) we have the intent to sell the security, (ii) it is more likely than not that we will be required to sell the security before recovery of the entire amortized cost basis or (iii) we do not expect to recover the entire amortized cost basis of the security. If impairment is considered on condition (i) or (ii) above, the entire difference between the amortized cost and the fair value of the debt security is recognized in earnings. If an impairment is considered based on condition (iii), the amount representing credit losses will be recognized in earnings and as an allowance for credit losses, and the amount relating to all other factors will be recognized in other comprehensive income. The following table summarizes our cash equivalents and available-for-sale debt investments: March 31, 2020 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents $ 351,965 $ 16 $ (11 ) $ 351,970 $ 314,676 $ 37,294 Short-term investments: Asset-backed securities 6,064 19 (5 ) 6,078 — 6,078 Commercial paper 1,986 — — 1,986 — 1,986 Corporate bonds 25,297 111 (42 ) 25,366 — 25,366 Municipal bonds 2,762 7 — 2,769 — 2,769 U.S. government agency bonds 7,482 12 (1 ) 7,493 — 7,493 U.S. government bonds 13,991 23 — 14,014 14,014 — Variable rate demand notes 557 — — 557 — 557 Total (2) (3) $ 410,104 $ 188 $ (59 ) $ 410,233 $ 328,690 $ 81,543 (1) All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) We have available-for-sale debt investments of $ 6.1 million with contractual maturities from 1 year to 5 years . Expected maturities can differ from contractual maturities because the issuers may have the right to call or prepay obligations without call or prepayment penalties, and we view our available-for-sale debt investments as available for current operations. (3) In April 2020, we increased our available-for-sale debt investments by $130.0 million . The following table summarizes our debt investments as of December 31, 2019: December 31, 2019 (In thousands) Cash equivalent money market funds (Level 1) (1) $ 384,474 Short-term investment government bond (Level 2) (2) 6,348 (1) The cash equivalent money market funds (Level 1) at December 31, 2019 have been corrected to include $286.7 million of cash equivalents that were excluded in previously reported amounts. There was no change to total cash and cash equivalents reported on our consolidated balance sheet. We determined this was immaterial to the prior period but have presented the balance as revised for comparability. (2) The fair market value of the security is $6.3 million

Factoring of Accounts Receivabl

Factoring of Accounts Receivable	3 Months Ended
	Mar. 31, 2020
Factoring of Accounts Receivable [Abstract]
Factoring of Accounts Receivable	Factoring of Accounts Receivable For certain accounts receivable, we use non-recourse factoring arrangements with third-party financial institutions to manage our working capital and cash flows. Under this program, we sell receivables to a financial institution for cash at a discount to the face amount. As part of the factoring arrangements, we perform certain collection and administrative functions for the receivables sold. For the three months ended March 31, 2020 and 2019, we sold receivables totaling $170.5 million and $155.7 million , net of discounts and fees of $1.0 million and $1.2 million , respectively.

Property, Plant and Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant And Equipment	Property, Plant and Equipment Property, plant and equipment consist of the following: March 31, December 31, 2019 (In thousands) Land $ 220,076 $ 219,785 Buildings and improvements 1,575,352 1,571,653 Machinery and equipment 5,335,424 5,303,729 Finance lease assets 34,401 34,158 Software and computer equipment 222,459 220,264 Furniture, fixtures and other equipment 19,844 19,740 Construction in progress 24,618 12,593 Total property, plant and equipment 7,432,174 7,381,922 Accumulated depreciation and amortization (5,064,428 ) (4,977,072 ) Total property, plant and equipment, net $ 2,367,746 $ 2,404,850 The following table summarizes our depreciation expense: For the Three Months Ended March 31, 2020 2019 (In thousands) Depreciation expense $ 123,501 $ 135,493

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2020
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following: March 31, December 31, (In thousands) Payroll and benefits $ 90,561 $ 115,693 Short-term operating lease liabilities 42,082 40,972 Income taxes payable 18,587 11,661 Deferred revenue and customer advances 13,881 16,177 Accrued severance plan obligations 11,192 13,408 Short-term finance lease liabilities 9,168 9,121 Accrued interest 3,629 11,638 Other accrued expenses 47,364 48,556 Total accrued expenses $ 236,464 $ 267,226

Debt

Debt	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Debt	Debt Following is a summary of short-term borrowings and long-term debt: March 31, December 31, (In thousands) Debt of Amkor Technology, Inc.: Senior notes: 6.625% Senior notes, due September 2027 $ 525,000 $ 525,000 Debt of subsidiaries: Amkor Technology Korea, Inc. (8): $30 million revolving credit facility, LIBOR plus the applicable bank rate (1) 15,000 — Term loan, fund floating rate plus 1.60%, due June 2020 (2) — 24,000 Term loan, applicable bank rate plus 2.03%, due July 2022 40,000 40,000 Term loan, applicable bank rate plus 2.03%, due September 2022 (3) 60,000 60,000 Term loan, LIBOR plus 2.56%, due December 2023 (4) 80,000 200,000 Term loan, applicable bank rate plus 1.98%, due December 2028 (2) 90,000 66,000 Amkor Technology Japan, Inc.: Short-term term loans, variable rate (5) 12,005 7,071 Term loan, fixed rate at 0.86%, due June 2022 20,923 23,018 Term loan, fixed rate at 0.60%, due July 2022 4,649 5,064 Term loan, fixed rate at 1.30%, due July 2023 169,239 179,541 Term loan, fixed rate at 1.35%, due December 2024 (4) 251,767 262,407 Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loan, LIBOR plus 1.60%, due March 2022 29,000 29,000 Term loan, LIBOR Plus 1.40%, due March 2022 19,250 19,250 Other: $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) (6) 150,000 — Revolving credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) (7) 56,000 20,000 1,522,833 1,460,351 Less: Unamortized discount and deferred debt costs, net (9,811 ) (10,117 ) Less: Short-term borrowings and current portion of long-term debt (141,521 ) (144,479 ) Long-term debt $ 1,371,501 $ 1,305,755 (1) In October 2019, we renewed our revolving credit facility agreement with availability of $30.0 million . Interest is payable monthly in arrears ( 2.97% as of March 31, 2020 ). In March 2020, we borrowed $15.0 million with the principal due in September 2020. As of March 31, 2020 , $15.0 million was available to be drawn. In April 2020, we borrowed the remaining $15.0 million with the principal due in October 2020. (2) In May 2015, we entered into a term loan agreement pursuant to which we may borrow up to $150.0 million for capital expenditures. Principal is payable at maturity in June 2020. Interest is payable quarterly in arrears, at a fund floating rate plus 1.60% . During the three months ended March 31, 2020 , we repaid the full $24.0 million outstanding on this term loan using the proceeds from our term loan due December 2028. (3) In July 2019, we entered into a $140.0 million term loan due September 2022. Principal is payable at maturity and interest is payable quarterly in arrears ( 3.59% as of March 31, 2020 ). As of March 31, 2020 , $80.0 million was available to be drawn. In April 2020, we borrowed an additional $40.0 million . (4) In January 2020, we used proceeds from our term loan due December 2024 to repay $120.0 million of our term loan due December 2023. (5) We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. Interest as of March 31, 2020 is at TIBOR plus 0.10% to 0.20% (weighted average of 0.21% as of March 31, 2020 ). As of March 31, 2020 , $6.5 million was available to be drawn. (6) In July 2018, our subsidiary, Amkor Technology Singapore Holding Pte, Ltd., entered into a $250.0 million senior secured revolving credit facility, which is guaranteed by Amkor Technology, Inc. The availability for our revolving credit facility is based on the amount of eligible accounts receivable. Principal is payable at maturity. Interest is payable monthly at LIBOR plus 1.25% to 1.75% ( 2.85% as of March 31, 2020 ). As of March 31, 2020 , $100.0 million was available to be drawn. (7) In December 2019, we entered into a $56.0 million revolving credit facility. Interest is payable monthly at TAIFX plus the applicable bank rate ( 3.41% as of March 31, 2020 ). In December 2019, we borrowed $20.0 million with the principal payable at maturity of the facility in December 2024. In the first quarter of 2020, we borrowed the remaining $36.0 million . In April 2020, we repaid $36.0 million of the revolving credit facility and immediately borrowed $36.0 million under the same agreement at a lower interest rate, with the principal payable in December 2024, based on incurring a certain level of qualified eligible transactions. (8) In April 2020, we entered into a term loan agreement pursuant to which we may borrow up to KRW ₩150.0 billion (approximately US $123 million ). Principal is payable at maturity and the variable interest is payable monthly. We immediately borrowed $123.0 million at an interest rate of 2.87% . Certain of our foreign debt is collateralized by the land, buildings, equipment and accounts receivable in the respective locations. The carrying value of all collateral exceeds the carrying amount of the collateralized debt. The debt of Amkor Technology, Inc. is structurally subordinated in right of payment to all existing and future debt and other liabilities of our subsidiaries. From time to time, Amkor Technology, Inc. and Amkor Technology Singapore Holding Pte, Ltd. guarantee certain debt of our subsidiaries. The agreements governing our indebtedness contain affirmative and negative covenants which restrict our ability to pay dividends and could restrict our operations. We have never paid a dividend to our stockholders, and we do not have any present plans for doing so. We were in compliance with all debt covenants at March 31, 2020 .

Pension Plans

Pension Plans	3 Months Ended
	Mar. 31, 2020
Retirement Benefits [Abstract]
Pension Plans	Pension Plans Foreign Defined Benefit Pension Plans Our subsidiaries in Japan, Korea, Malaysia, the Philippines and Taiwan sponsor defined benefit pension plans. Charges to expense are based upon actuarial analyses. The components of net periodic pension cost for these defined benefit pension plans are as follows: For the Three Months Ended March 31, 2020 2019 (In thousands) Service cost $ 7,536 $ 7,977 Interest cost 1,247 1,324 Expected return on plan assets (1,374 ) (1,618 ) Recognized actuarial gain 14 (94 ) Net periodic pension cost $ 7,423 $ 7,589 The components of net periodic pension cost other than the service cost component are included in other (income) expense, net in our Consolidated Statements of Income. Defined Contribution Pension Plans We sponsor defined contribution pension plans in Korea, Malaysia, Taiwan and the U.S. The following table summarizes our defined contribution expense: For the Three Months Ended March 31, 2020 2019 (In thousands) Defined contribution expense $ 4,816 $ 4,405

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The accounting framework for determining fair value includes a hierarchy for ranking the quality and reliability of the information used to measure fair value, which enables the reader of the financial statements to assess the inputs used to develop those measurements. The fair value hierarchy consists of three tiers as follows: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, model-based valuation techniques for which all significant assumptions are observable in the market or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data. The fair values of cash, accounts receivable, trade accounts payable, capital expenditures payable, and certain other current assets and accrued expenses approximate carrying values because of their short-term nature. The carrying value of certain other non-current assets and liabilities approximates fair value. Our assets and liabilities recorded at fair value on a recurring basis include restricted cash money market funds and short-term investments, including investments classified as cash equivalents. We also review goodwill for impairment annually during the fourth quarter of each year. Cash equivalent money market funds and restricted cash money market funds are invested in U.S. money market funds and various U.S. and foreign bank operating and time deposit accounts, which are due on demand or carry a maturity date of less than three months when purchased. No restrictions have been imposed on us regarding withdrawal of balances with respect to our cash equivalents as a result of liquidity or other credit market issues affecting the money market funds we invest in or the counterparty financial institutions holding our deposits. Short-term investments, including money market funds ( Note 7 ), are valued as follows: • Level 1: using quoted market prices in active markets for identical assets. • Level 2: using quoted market prices for similar instruments or non-binding market prices that are corroborated by observable market data. We use inputs such as actual trade data, benchmark yields, broker/dealer quotes, and other similar data, which are obtained from quoted market prices, and independent pricing vendors to determine the fair value of these assets and liabilities. Our derivative financial instruments are valued using quoted market prices for similar assets. Counterparties to these derivative contracts are highly rated financial institutions. We also measure certain assets and liabilities, including property, plant and equipment and goodwill, at fair value on a nonrecurring basis. We measure the fair value of our debt for disclosure purposes. The following table presents the fair value of financial instruments that are not recorded at fair value on a recurring basis: March 31, 2020 December 31, 2019 Fair Value Carrying Value Fair Value Carrying Value (In thousands) Senior notes (Level 1) $ 488,701 $ 519,355 $ 576,875 $ 519,211 Revolving credit facilities and term loans (Level 2) 980,901 993,667 940,756 931,023 Total debt $ 1,469,602 $ 1,513,022 $ 1,517,631 $ 1,450,234 The estimated fair value of our senior notes is based primarily on quoted market prices reported on or near the respective balance sheet dates. The estimated fair value of our revolving credit facilities and term loans is calculated using a discounted cash flow analysis, which utilizes market-based assumptions including forward interest rates adjusted for credit risk.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We generally warrant that our services will be performed in a professional and workmanlike manner and in compliance with our customers’ specifications. We accrue costs for known warranty issues. Historically, our warranty costs have been immaterial. Legal Proceedings We are involved in claims and legal proceedings and may become involved in other legal matters arising in the ordinary course of our business. We evaluate these claims and legal matters on a case-by-case basis to make a determination as to the impact, if any, on our business, liquidity, results of operations, financial condition or cash flows. Although the outcome of these matters is uncertain, we believe that the ultimate outcome of these claims and proceedings, individually and in the aggregate, will not have a material adverse impact to us. Our evaluation of the potential impact of these claims and legal proceedings on our business, liquidity, results of operations, financial condition or cash flows could change in the future. In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Restructuring and Other Exit Ac

Restructuring and Other Exit Activities	3 Months Ended
	Mar. 31, 2020
Restructuring and Related Activities [Abstract]
Restructuring and Other Exit Activities	Restructuring and Other Exit Activities As part of our ongoing efforts to improve our manufacturing operations and manage costs, we regularly evaluate our staffing levels and facility requirements compared to business needs. The following table summarizes our exit activities associated with these efforts. “Charges” represents the initial charge related to the exit activity. “Cash Payments” consists of the utilization of “Charges.” “Non-cash Amounts” consists of translation adjustments. Japan Consolidation Activities During the three months ended March 31, 2020 , we recorded restructuring charges of $1.9 million associated with our Japan footprint consolidation efforts. We recorded these charges to selling, general and administrative expenses within the Consolidated Statements of Income. All amounts accrued at March 31, 2020 are classified as current liabilities. We expect to complete our restructuring actions in the first half of fiscal 2021. Facility Costs (1) Employee Other Exit Costs (2) Total (In thousands) Accrual at December 31, 2019 $ 2,196 $ 271 $ 174 $ 2,641 Charges 1,310 30 579 1,919 Cash Payments (2,482 ) (300 ) (660 ) (3,442 ) Non-cash Amounts (12 ) (1 ) (2 ) (15 ) Accrual at March 31, 2020 $ 1,012 $ — $ 91 $ 1,103 Total cumulative charges incurred to date $ 5,809 $ 2,740 $ 1,325 $ 9,874 Estimated additional charges to be incurred $ 11,000 $ 5,000 $ 3,000 $ 19,000 (1) Facility costs primarily consist of equipment relocation costs directly resulting from the restructuring actions. (2) Other exit costs primarily consist of employee relocation and training costs directly resulting from the restructuring actions.

Interim Financial Statements (P

Interim Financial Statements (Policies)	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation. The Consolidated Financial Statements and related disclosures as of March 31, 2020 , and for the three months ended March 31, 2020 and 2019 , are unaudited, pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The December 31, 2019 Consolidated Balance Sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. In our opinion, these financial statements include all adjustments (consisting only of normal recurring adjustments) necessary for the fair statement of the results for the interim periods. These financial statements should be read in conjunction with the financial statements included in our Annual Report for the year ended December 31, 2019 , filed on Form 10-K with the SEC on February 19, 2020. The results of operations for the three months ended March 31, 2020
Reclassifications	Certain prior year amounts have been reclassified to conform to current year presentation.
Use of Estimates	Use of Estimates. The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments, including the impact of Covid-19 and any worsening of the global business and economic environment.
Goodwill	Goodwill.
Income Taxes	We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and results of recent operations. We maintain a valuation allowance on certain U.S. and foreign deferred tax assets. Such valuation allowances are released as the related tax benefits are realized or when sufficient evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized.
Commitments and Contingencies	In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Net Sales by Product Group an_2

Net Sales by Product Group and End Market (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Net sales by product group and end market	Net sales by product group consist of the following: For the Three Months Ended March 31, 2020 2019 (In thousands) Advanced products (1) $ 705,158 $ 422,446 Mainstream products (2) 447,458 472,518 Total net sales $ 1,152,616 $ 894,964 (1) Advanced products include flip chip and wafer-level processing and related test services. (2) Mainstream products include wirebond packaging and related test services. Net sales by end market consist of the following : For the Three Months Ended March 31, 2020 2019 Communications (handheld devices, smartphones, tablets) 38 % 38 % Consumer (connected home, set-top boxes, televisions, visual imaging, wearables) 24 % 14 % Automotive, industrial and other (driver assist, infotainment, performance, safety) 23 % 28 % Computing (datacenter, infrastructure, PC/laptop, storage) 15 % 20 % Total net sales 100 % 100 %

Other Income and Expense (Table

Other Income and Expense (Tables)	3 Months Ended
	Mar. 31, 2020
Other Income and Expenses [Abstract]
Schedule of other income and expense	Other income and expense consists of the following: For the Three Months Ended March 31, 2020 2019 (In thousands) Interest income $ (2,258 ) $ (2,064 ) Foreign currency (gain) loss, net (229 ) (2,013 ) Loss on debt retirement 428 — Other (256 ) (488 ) Other (income) expense, net $ (2,315 ) $ (4,565 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per share	The following table summarizes the computation of basic and diluted EPS: For the Three Months Ended March 31, 2020 2019 (In thousands, except per share data) Net income (loss) attributable to Amkor common stockholders $ 63,889 $ (22,879 ) Weighted-average number of common shares outstanding - basic 240,919 239,414 Effect of dilutive securities: Stock options and restricted share awards 414 — Weighted-average number of common shares outstanding - diluted 241,333 239,414 Net income (loss) attributable to Amkor per common share: Basic $ 0.27 $ (0.10 ) Diluted 0.26 (0.10 )
Summary of potential shares of common stock excluded from diluted earnings per share	The following table summarizes the potential shares of common stock that were excluded from diluted EPS because the effect of including these potential shares was anti-dilutive: For the Three Months Ended March 31, 2020 2019 (In thousands) Stock options and restricted share awards 4,321 7,123

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Changes in accumulated other comprehensive income (loss), net of tax	Changes in accumulated other comprehensive income (loss), net of tax, consist of the following: Unrealized Gains (Losses) on Available-for-Sale Debt Investments Defined Benefit Pension (1) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2019 $ — $ (4,820 ) $ 23,935 $ 19,115 Other comprehensive income (loss) before reclassifications 108 — 475 583 Amounts reclassified from accumulated other comprehensive income (loss) — 11 — 11 Other comprehensive income (loss) 108 11 475 594 Accumulated other comprehensive income (loss) at March 31, 2020 $ 108 $ (4,809 ) $ 24,410 $ 19,709 Defined Benefit Pension (1) Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2018 $ 2,659 $ 21,153 $ 23,812 Other comprehensive income (loss) before reclassifications — (2,224 ) $ (2,224 ) Amounts reclassified from accumulated other comprehensive income (loss) (132 ) — $ (132 ) Other comprehensive income (loss) (132 ) (2,224 ) (2,356 ) Accumulated other comprehensive income (loss) at March 31, 2019 $ 2,527 $ 18,929 $ 21,456 (1) Amounts reclassified out of accumulated other comprehensive income (loss) are included as a component of net periodic pension cost ( Note 12 ) or other (income) expense, net.

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Summary of Cash Equivalents and Available-for-Sale Debt Investments	The following table summarizes our cash equivalents and available-for-sale debt investments: March 31, 2020 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents $ 351,965 $ 16 $ (11 ) $ 351,970 $ 314,676 $ 37,294 Short-term investments: Asset-backed securities 6,064 19 (5 ) 6,078 — 6,078 Commercial paper 1,986 — — 1,986 — 1,986 Corporate bonds 25,297 111 (42 ) 25,366 — 25,366 Municipal bonds 2,762 7 — 2,769 — 2,769 U.S. government agency bonds 7,482 12 (1 ) 7,493 — 7,493 U.S. government bonds 13,991 23 — 14,014 14,014 — Variable rate demand notes 557 — — 557 — 557 Total (2) (3) $ 410,104 $ 188 $ (59 ) $ 410,233 $ 328,690 $ 81,543 (1) All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) We have available-for-sale debt investments of $ 6.1 million with contractual maturities from 1 year to 5 years . Expected maturities can differ from contractual maturities because the issuers may have the right to call or prepay obligations without call or prepayment penalties, and we view our available-for-sale debt investments as available for current operations. (3) In April 2020, we increased our available-for-sale debt investments by $130.0 million
Summary of Debt Securities Available-for-sale	The following table summarizes our cash equivalents and available-for-sale debt investments: March 31, 2020 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents $ 351,965 $ 16 $ (11 ) $ 351,970 $ 314,676 $ 37,294 Short-term investments: Asset-backed securities 6,064 19 (5 ) 6,078 — 6,078 Commercial paper 1,986 — — 1,986 — 1,986 Corporate bonds 25,297 111 (42 ) 25,366 — 25,366 Municipal bonds 2,762 7 — 2,769 — 2,769 U.S. government agency bonds 7,482 12 (1 ) 7,493 — 7,493 U.S. government bonds 13,991 23 — 14,014 14,014 — Variable rate demand notes 557 — — 557 — 557 Total (2) (3) $ 410,104 $ 188 $ (59 ) $ 410,233 $ 328,690 $ 81,543 (1) All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) We have available-for-sale debt investments of $ 6.1 million with contractual maturities from 1 year to 5 years . Expected maturities can differ from contractual maturities because the issuers may have the right to call or prepay obligations without call or prepayment penalties, and we view our available-for-sale debt investments as available for current operations. (3) In April 2020, we increased our available-for-sale debt investments by $130.0 million
Schedule of Cash and Cash Equivalents	The following table summarizes our cash equivalents and available-for-sale debt investments: March 31, 2020 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents $ 351,965 $ 16 $ (11 ) $ 351,970 $ 314,676 $ 37,294 Short-term investments: Asset-backed securities 6,064 19 (5 ) 6,078 — 6,078 Commercial paper 1,986 — — 1,986 — 1,986 Corporate bonds 25,297 111 (42 ) 25,366 — 25,366 Municipal bonds 2,762 7 — 2,769 — 2,769 U.S. government agency bonds 7,482 12 (1 ) 7,493 — 7,493 U.S. government bonds 13,991 23 — 14,014 14,014 — Variable rate demand notes 557 — — 557 — 557 Total (2) (3) $ 410,104 $ 188 $ (59 ) $ 410,233 $ 328,690 $ 81,543 (1) All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and it is not more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) We have available-for-sale debt investments of $ 6.1 million with contractual maturities from 1 year to 5 years . Expected maturities can differ from contractual maturities because the issuers may have the right to call or prepay obligations without call or prepayment penalties, and we view our available-for-sale debt investments as available for current operations. (3) In April 2020, we increased our available-for-sale debt investments by $130.0 million
Valuation of money market funds	The following table summarizes our debt investments as of December 31, 2019: December 31, 2019 (In thousands) Cash equivalent money market funds (Level 1) (1) $ 384,474 Short-term investment government bond (Level 2) (2) 6,348 (1) The cash equivalent money market funds (Level 1) at December 31, 2019 have been corrected to include $286.7 million of cash equivalents that were excluded in previously reported amounts. There was no change to total cash and cash equivalents reported on our consolidated balance sheet. We determined this was immaterial to the prior period but have presented the balance as revised for comparability. (2) The fair market value of the security is $6.3 million

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Summary of property, plant and equipment and depreciation expense	Property, plant and equipment consist of the following: March 31, December 31, 2019 (In thousands) Land $ 220,076 $ 219,785 Buildings and improvements 1,575,352 1,571,653 Machinery and equipment 5,335,424 5,303,729 Finance lease assets 34,401 34,158 Software and computer equipment 222,459 220,264 Furniture, fixtures and other equipment 19,844 19,740 Construction in progress 24,618 12,593 Total property, plant and equipment 7,432,174 7,381,922 Accumulated depreciation and amortization (5,064,428 ) (4,977,072 ) Total property, plant and equipment, net $ 2,367,746 $ 2,404,850 The following table summarizes our depreciation expense: For the Three Months Ended March 31, 2020 2019 (In thousands) Depreciation expense $ 123,501 $ 135,493

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Payables and Accruals [Abstract]
Summary of accrued expenses	Accrued expenses consist of the following: March 31, December 31, (In thousands) Payroll and benefits $ 90,561 $ 115,693 Short-term operating lease liabilities 42,082 40,972 Income taxes payable 18,587 11,661 Deferred revenue and customer advances 13,881 16,177 Accrued severance plan obligations 11,192 13,408 Short-term finance lease liabilities 9,168 9,121 Accrued interest 3,629 11,638 Other accrued expenses 47,364 48,556 Total accrued expenses $ 236,464 $ 267,226

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Summary of short-term borrowings and long-term debt	Following is a summary of short-term borrowings and long-term debt: March 31, December 31, (In thousands) Debt of Amkor Technology, Inc.: Senior notes: 6.625% Senior notes, due September 2027 $ 525,000 $ 525,000 Debt of subsidiaries: Amkor Technology Korea, Inc. (8): $30 million revolving credit facility, LIBOR plus the applicable bank rate (1) 15,000 — Term loan, fund floating rate plus 1.60%, due June 2020 (2) — 24,000 Term loan, applicable bank rate plus 2.03%, due July 2022 40,000 40,000 Term loan, applicable bank rate plus 2.03%, due September 2022 (3) 60,000 60,000 Term loan, LIBOR plus 2.56%, due December 2023 (4) 80,000 200,000 Term loan, applicable bank rate plus 1.98%, due December 2028 (2) 90,000 66,000 Amkor Technology Japan, Inc.: Short-term term loans, variable rate (5) 12,005 7,071 Term loan, fixed rate at 0.86%, due June 2022 20,923 23,018 Term loan, fixed rate at 0.60%, due July 2022 4,649 5,064 Term loan, fixed rate at 1.30%, due July 2023 169,239 179,541 Term loan, fixed rate at 1.35%, due December 2024 (4) 251,767 262,407 Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loan, LIBOR plus 1.60%, due March 2022 29,000 29,000 Term loan, LIBOR Plus 1.40%, due March 2022 19,250 19,250 Other: $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) (6) 150,000 — Revolving credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) (7) 56,000 20,000 1,522,833 1,460,351 Less: Unamortized discount and deferred debt costs, net (9,811 ) (10,117 ) Less: Short-term borrowings and current portion of long-term debt (141,521 ) (144,479 ) Long-term debt $ 1,371,501 $ 1,305,755 (1) In October 2019, we renewed our revolving credit facility agreement with availability of $30.0 million . Interest is payable monthly in arrears ( 2.97% as of March 31, 2020 ). In March 2020, we borrowed $15.0 million with the principal due in September 2020. As of March 31, 2020 , $15.0 million was available to be drawn. In April 2020, we borrowed the remaining $15.0 million with the principal due in October 2020. (2) In May 2015, we entered into a term loan agreement pursuant to which we may borrow up to $150.0 million for capital expenditures. Principal is payable at maturity in June 2020. Interest is payable quarterly in arrears, at a fund floating rate plus 1.60% . During the three months ended March 31, 2020 , we repaid the full $24.0 million outstanding on this term loan using the proceeds from our term loan due December 2028. (3) In July 2019, we entered into a $140.0 million term loan due September 2022. Principal is payable at maturity and interest is payable quarterly in arrears ( 3.59% as of March 31, 2020 ). As of March 31, 2020 , $80.0 million was available to be drawn. In April 2020, we borrowed an additional $40.0 million . (4) In January 2020, we used proceeds from our term loan due December 2024 to repay $120.0 million of our term loan due December 2023. (5) We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. Interest as of March 31, 2020 is at TIBOR plus 0.10% to 0.20% (weighted average of 0.21% as of March 31, 2020 ). As of March 31, 2020 , $6.5 million was available to be drawn. (6) In July 2018, our subsidiary, Amkor Technology Singapore Holding Pte, Ltd., entered into a $250.0 million senior secured revolving credit facility, which is guaranteed by Amkor Technology, Inc. The availability for our revolving credit facility is based on the amount of eligible accounts receivable. Principal is payable at maturity. Interest is payable monthly at LIBOR plus 1.25% to 1.75% ( 2.85% as of March 31, 2020 ). As of March 31, 2020 , $100.0 million was available to be drawn. (7) In December 2019, we entered into a $56.0 million revolving credit facility. Interest is payable monthly at TAIFX plus the applicable bank rate ( 3.41% as of March 31, 2020 ). In December 2019, we borrowed $20.0 million with the principal payable at maturity of the facility in December 2024. In the first quarter of 2020, we borrowed the remaining $36.0 million . In April 2020, we repaid $36.0 million of the revolving credit facility and immediately borrowed $36.0 million under the same agreement at a lower interest rate, with the principal payable in December 2024, based on incurring a certain level of qualified eligible transactions. (8) In April 2020, we entered into a term loan agreement pursuant to which we may borrow up to KRW ₩150.0 billion (approximately US $123 million ). Principal is payable at maturity and the variable interest is payable monthly. We immediately borrowed $123.0 million at an interest rate of 2.87%

Pension Plans (Tables)

Pension Plans (Tables)	3 Months Ended
	Mar. 31, 2020
Retirement Benefits [Abstract]
Components of net periodic pension cost	The components of net periodic pension cost for these defined benefit pension plans are as follows: For the Three Months Ended March 31, 2020 2019 (In thousands) Service cost $ 7,536 $ 7,977 Interest cost 1,247 1,324 Expected return on plan assets (1,374 ) (1,618 ) Recognized actuarial gain 14 (94 ) Net periodic pension cost $ 7,423 $ 7,589
Summary of defined contribution expense	The following table summarizes our defined contribution expense: For the Three Months Ended March 31, 2020 2019 (In thousands) Defined contribution expense $ 4,816 $ 4,405

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair value of financial instruments that are not recorded at fair value on recurring basis	The following table presents the fair value of financial instruments that are not recorded at fair value on a recurring basis: March 31, 2020 December 31, 2019 Fair Value Carrying Value Fair Value Carrying Value (In thousands) Senior notes (Level 1) $ 488,701 $ 519,355 $ 576,875 $ 519,211 Revolving credit facilities and term loans (Level 2) 980,901 993,667 940,756 931,023 Total debt $ 1,469,602 $ 1,513,022 $ 1,517,631 $ 1,450,234

Restructuring and Other Exit _2

Restructuring and Other Exit Activities (Tables)	3 Months Ended
	Mar. 31, 2020
Restructuring and Related Activities [Abstract]
Summary of Exit Activities	Facility Costs (1) Employee Other Exit Costs (2) Total (In thousands) Accrual at December 31, 2019 $ 2,196 $ 271 $ 174 $ 2,641 Charges 1,310 30 579 1,919 Cash Payments (2,482 ) (300 ) (660 ) (3,442 ) Non-cash Amounts (12 ) (1 ) (2 ) (15 ) Accrual at March 31, 2020 $ 1,012 $ — $ 91 $ 1,103 Total cumulative charges incurred to date $ 5,809 $ 2,740 $ 1,325 $ 9,874 Estimated additional charges to be incurred $ 11,000 $ 5,000 $ 3,000 $ 19,000 (1) Facility costs primarily consist of equipment relocation costs directly resulting from the restructuring actions. (2) Other exit costs primarily consist of employee relocation and training costs directly resulting from the restructuring actions.

Interim Financial Statements (D

Interim Financial Statements (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Unbilled receivables	$ 131.3	$ 125.4

Net Sales by Product Group an_3

Net Sales by Product Group and End Market - Product Group (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Net sales by product group	$ 1,152,616	$ 894,964
Advanced products
Disaggregation of Revenue [Line Items]
Net sales by product group	705,158	422,446
Mainstream products
Disaggregation of Revenue [Line Items]
Net sales by product group	$ 447,458	$ 472,518

Net Sales by Product Group an_4

Net Sales by Product Group and End Market - End Market (Details)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total net sales	100.00%	100.00%
Revenue from Contract with Customer | End Market | Communications (handheld devices, smartphones, tablets)
Disaggregation of Revenue [Line Items]
Total net sales	38.00%	38.00%
Revenue from Contract with Customer | End Market | Consumer (connected home, set-top boxes, televisions, visual imaging, wearables)
Disaggregation of Revenue [Line Items]
Total net sales	24.00%	14.00%
Revenue from Contract with Customer | End Market | Automotive, industrial and other (driver assist, infotainment, performance, safety)
Disaggregation of Revenue [Line Items]
Total net sales	23.00%	28.00%
Revenue from Contract with Customer | End Market | Computing (datacenter, infrastructure, PC/laptop, storage)
Disaggregation of Revenue [Line Items]
Total net sales	15.00%	20.00%

Other Income and Expense (Detai

Other Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Income and Expenses [Abstract]
Interest income	$ (2,258)	$ (2,064)
Foreign currency (gain) loss, net	(229)	(2,013)
Loss on debt retirement	428	0
Other	(256)	(488)
Other (income) expense, net	$ (2,315)	$ (4,565)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax expense	$ 4,846	$ 21,380
Gross unrecognized tax benefits	$ 23,100		$ 26,200

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income (loss) attributable to Amkor common stockholders	$ 63,889	$ (22,879)
Weighted-average number of common shares outstanding - basic	240,919	239,414
Effect of dilutive securities:
Stock options and restricted share awards (in shares)	414	0
Weighted-average number of common shares outstanding - diluted	241,333	239,414
Net income (loss) attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.27	$ (0.10)
Diluted (in dollars per share)	$ 0.26	$ (0.10)

Earnings Per Share - Potential

Earnings Per Share - Potential Shares of Common Stock Excluded from Diluted EPS (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stock options and restricted share awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options and restricted share awards	4,321	7,123

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,990,239	$ 1,855,900
Other comprehensive income (loss) before reclassifications	583	(2,224)
Amounts reclassified from accumulated other comprehensive income (loss)	11	(132)
Total other comprehensive income (loss)	594	(2,356)
Balance at end of period	2,058,625	1,832,582
Unrealized Gains (Losses) on Short-term Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	0
Other comprehensive income (loss) before reclassifications	108
Amounts reclassified from accumulated other comprehensive income (loss)	0
Total other comprehensive income (loss)	108
Balance at end of period	108
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(4,820)	2,659
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	11	(132)
Total other comprehensive income (loss)	11	(132)
Balance at end of period	(4,809)	2,527
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	23,935	21,153
Other comprehensive income (loss) before reclassifications	475	(2,224)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	475	(2,224)
Balance at end of period	24,410	18,929
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	19,115	23,812
Total other comprehensive income (loss)	594	(2,356)
Balance at end of period	$ 19,709	$ 21,456

Investments - Summary of Short

Investments - Summary of Short term Investments (Details) - USD ($) $ in Thousands	1 Months Ended
	Apr. 30, 2020	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		$ 410,104
Gross Unrealized Gains		188
Gross Unrealized Losses		(59)
Total Fair Value		410,233
Available-for-sale investments		6,100
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		6,064
Gross Unrealized Gains		19
Gross Unrealized Losses		(5)
Total Fair Value		6,078
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		2,762
Gross Unrealized Gains		7
Gross Unrealized Losses		0
Total Fair Value		2,769
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,986
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Total Fair Value		1,986
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		25,297
Gross Unrealized Gains		111
Gross Unrealized Losses		(42)
Total Fair Value		25,366
U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		7,482
Gross Unrealized Gains		12
Gross Unrealized Losses		(1)
Total Fair Value		7,493
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		13,991
Gross Unrealized Gains		23
Gross Unrealized Losses		0
Total Fair Value		14,014
Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		557
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Total Fair Value		557
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		351,965
Gross Unrealized Gains		16
Gross Unrealized Losses		(11)
Total Fair Value		351,970
Level 1
Debt Securities, Available-for-sale [Line Items]
Cash equivalents		314,676
Total		328,690
Level 1 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 1 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 1 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 1 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 1 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 1 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		14,014
Level 1 | Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 2
Debt Securities, Available-for-sale [Line Items]
Cash equivalents		37,294
Total		81,543
Level 2 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		6,078
Level 2 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		2,769
Level 2 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		1,986
Level 2 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		25,366
Level 2 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		7,493
Level 2 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		0
Level 2 | Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Total Fair Value		$ 557
Subsequent Event
Debt Securities, Available-for-sale [Line Items]
Increase in available-for-sale debt investments	$ 130,000

Investments - Valuation of Mone

Investments - Valuation of Money Market Funds (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt and Equity Securities, FV-NI [Line Items]
Short-term investment government bond	$ 410,233
Level 1
Debt and Equity Securities, FV-NI [Line Items]
Cash equivalent money market funds	314,676
Level 2
Debt and Equity Securities, FV-NI [Line Items]
Cash equivalent money market funds	37,294
U.S. government bonds
Debt and Equity Securities, FV-NI [Line Items]
Short-term investment government bond	14,014
U.S. government bonds | Level 1
Debt and Equity Securities, FV-NI [Line Items]
Short-term investment government bond	14,014
U.S. government bonds | Level 2
Debt and Equity Securities, FV-NI [Line Items]
Short-term investment government bond	$ 0
U.S. government bonds | Fair Value, Recurring
Debt and Equity Securities, FV-NI [Line Items]
Short-term investment government bond		$ 6,300
U.S. government bonds | Fair Value, Recurring | Level 2
Debt and Equity Securities, FV-NI [Line Items]
Short-term investment government bond		6,348
Money Market Funds | Fair Value, Recurring | Level 1
Debt and Equity Securities, FV-NI [Line Items]
Cash equivalent money market funds		384,474
Money Market Funds | Fair Value, Recurring | Level 1 | Revision of Prior Period, Adjustment
Debt and Equity Securities, FV-NI [Line Items]
Cash equivalent money market funds		$ 286,700

Factoring of Accounts Receiva_2

Factoring of Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Total Factored
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 170.5	$ 155.7
Discounts and Fees
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 1	$ 1.2

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Finance lease assets	$ 34,401	$ 34,158
Total property, plant and equipment	7,432,174	7,381,922
Accumulated depreciation and amortization	(5,064,428)	(4,977,072)
Total property, plant and equipment, net	2,367,746	2,404,850
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	220,076	219,785
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,575,352	1,571,653
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,335,424	5,303,729
Software and computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	222,459	220,264
Furniture, fixtures and other equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	19,844	19,740
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 24,618	$ 12,593

Property, Plant and Equipment_2

Property, Plant and Equipment - Summary of Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 123,501	$ 135,493

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Payroll and benefits	$ 90,561	$ 115,693
Short-term operating lease liabilities	42,082	40,972
Income taxes payable	18,587	11,661
Deferred revenue and customer advances	13,881	16,177
Accrued severance plan obligations	11,192	13,408
Short-term finance lease liabilities	9,168	9,121
Accrued interest	3,629	11,638
Other accrued expenses	47,364	48,556
Total accrued expenses	$ 236,464	$ 267,226

Debt (Details)

Debt (Details) ₩ in Billions	1 Months Ended						3 Months Ended
	Apr. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Jan. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jul. 31, 2018USD ($)	May 31, 2015USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Apr. 30, 2020KRW (₩)	Oct. 31, 2019USD ($)	Jul. 31, 2019USD ($)
Debt Instrument [Line Items]
Long-term Debt		$ 1,522,833,000		$ 1,460,351,000			$ 1,522,833,000
Less: Unamortized discount and deferred debt costs, net		(9,811,000)		(10,117,000)			(9,811,000)
Less: Short-term borrowings and current portion of long-term debt		(141,521,000)		(144,479,000)			(141,521,000)
Long-term debt		1,371,501,000		1,305,755,000			1,371,501,000
Proceeds from revolving credit facilities							201,000,000	$ 0
Payments of long-term debt							$ 172,336,000	$ 63,636,000
Term loan, LIBOR plus 1.60%, due March 2022 | China | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							1.60%
Term Loan, LIBOR plus 1.40% due March 2022 | China | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							1.40%
Senior Notes | 6.625% Senior notes, due September 2027
Debt Instrument [Line Items]
Debt		$ 525,000,000		525,000,000			$ 525,000,000
Stated interest rate (as a percent)		6.625%					6.625%
Line of Credit | Revolving Credit Facility | Korea
Debt Instrument [Line Items]
Debt		$ 15,000,000		0			$ 15,000,000
Credit facility, borrowing capacity		$ 30,000,000					$ 30,000,000			$ 30,000,000
Interest rate at period end (as a percent)		2.97%					2.97%
Proceeds from revolving credit facilities		$ 15,000,000
Unused borrowing capacity		$ 15,000,000					$ 15,000,000
Line of Credit | Revolving Credit Facility | Korea | Subsequent Event
Debt Instrument [Line Items]
Proceeds from revolving credit facilities	$ 15,000,000
Line of Credit | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, borrowing capacity					$ 250,000,000
Interest rate at period end (as a percent)		2.85%					2.85%
Remaining borrowing capacity		$ 100,000,000					$ 100,000,000
Line of Credit | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					1.25%
Line of Credit | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					1.75%
Line of Credit | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | Singapore
Debt Instrument [Line Items]
Debt		150,000,000		0			150,000,000
Credit facility, borrowing capacity		250,000,000					$ 250,000,000
Line of Credit | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | Singapore | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							1.25%
Line of Credit | $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) | Revolving Credit Facility | Singapore | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							1.75%
Line of Credit | Revolving credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) | Revolving Credit Facility | Taiwan
Debt Instrument [Line Items]
Debt		$ 56,000,000		20,000,000			$ 56,000,000
Credit facility, borrowing capacity				56,000,000
Interest rate at period end (as a percent)		3.41%					3.41%
Proceeds from revolving credit facilities				20,000,000			$ 36,000,000
Line of Credit | Revolving credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) | Revolving Credit Facility | Taiwan | Subsequent Event
Debt Instrument [Line Items]
Proceeds from revolving credit facilities	36,000,000
Repayments of revolving credit facilities	36,000,000
Subsidiary Term Loans | Term loan, fund floating rate plus 1.60%, due June 2020 | Korea
Debt Instrument [Line Items]
Debt		$ 0		24,000,000			0
Face amount of debt						$ 150,000,000
Payments of long-term debt							$ 24,000,000
Subsidiary Term Loans | Term loan, fund floating rate plus 1.60%, due June 2020 | Korea | Fund Floating Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)						1.60%	1.60%
Subsidiary Term Loans | Term loan, applicable bank rate plus 2.03%, due July 2022 | Korea
Debt Instrument [Line Items]
Debt		40,000,000		40,000,000			$ 40,000,000
Subsidiary Term Loans | Term loan, applicable bank rate plus 2.03%, due July 2022 | Korea | Applicable Bank Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							2.03%
Subsidiary Term Loans | Term loan, applicable bank rate plus 2.03%, due September 2022 | Korea
Debt Instrument [Line Items]
Debt		$ 60,000,000		60,000,000			$ 60,000,000
Interest rate at period end (as a percent)		3.59%					3.59%
Unused borrowing capacity		$ 80,000,000					$ 80,000,000
Face amount of debt											$ 140,000,000
Subsidiary Term Loans | Term loan, applicable bank rate plus 2.03%, due September 2022 | Korea | Subsequent Event
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt	$ 40,000,000
Subsidiary Term Loans | Term loan, applicable bank rate plus 2.03%, due September 2022 | Korea | Applicable Bank Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							2.03%
Subsidiary Term Loans | Term loan, LIBOR plus 2.56%, due December 2023 | Korea
Debt Instrument [Line Items]
Debt		80,000,000		200,000,000			$ 80,000,000
Subsidiary Term Loans | Term loan, LIBOR plus 2.56%, due December 2023 | Korea | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							2.56%
Subsidiary Term Loans | Term loan, LIBOR plus 2.56%, due December 2023 | Japan
Debt Instrument [Line Items]
Payments of long-term debt			$ 120,000,000
Subsidiary Term Loans | Term loan, applicable bank rate plus 1.98%, due December 2028 | Korea
Debt Instrument [Line Items]
Debt		90,000,000		66,000,000			$ 90,000,000
Subsidiary Term Loans | Term loan, applicable bank rate plus 1.98%, due December 2028 | Korea | Applicable Bank Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							1.98%
Subsidiary Term Loans | Short-term term loans, variable rate | Japan
Debt Instrument [Line Items]
Debt		12,005,000		7,071,000			$ 12,005,000
Unused borrowing capacity		$ 6,500,000					$ 6,500,000
Subsidiary Term Loans | Short-term term loans, variable rate | Japan | Weighted Average
Debt Instrument [Line Items]
Weighted average interest rate (as a percent)		0.21%					0.21%
Subsidiary Term Loans | Short-term term loans, variable rate | Japan | TIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							0.10%
Subsidiary Term Loans | Short-term term loans, variable rate | Japan | TIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)							0.20%
Subsidiary Term Loans | Term loan, fixed rate at 0.86%, due June 2022 | Japan
Debt Instrument [Line Items]
Debt		$ 20,923,000		23,018,000			$ 20,923,000
Stated interest rate (as a percent)		0.86%					0.86%
Subsidiary Term Loans | Term loan, fixed rate at 0.60%, due July 2022 | Japan
Debt Instrument [Line Items]
Debt		$ 4,649,000		5,064,000			$ 4,649,000
Stated interest rate (as a percent)		0.60%					0.60%
Subsidiary Term Loans | Term loan, fixed rate at 1.30%, due July 2023 | Japan
Debt Instrument [Line Items]
Debt		$ 169,239,000		179,541,000			$ 169,239,000
Stated interest rate (as a percent)		1.30%					1.30%
Subsidiary Term Loans | Term loan, fixed rate at 1.35%, due December 2024 | Japan
Debt Instrument [Line Items]
Debt		$ 251,767,000		262,407,000			$ 251,767,000
Stated interest rate (as a percent)		1.35%					1.35%
Proceeds from issuance of long-term debt			$ 120,000,000
Subsidiary Term Loans | Term loan, LIBOR plus 1.60%, due March 2022 | China
Debt Instrument [Line Items]
Debt		$ 29,000,000		29,000,000			$ 29,000,000
Subsidiary Term Loans | Term Loan, LIBOR plus 1.40% due March 2022 | China
Debt Instrument [Line Items]
Debt		$ 19,250,000		$ 19,250,000			$ 19,250,000
Subsidiary Term Loans | Term loan, entered in April 2020 | Korea | Subsequent Event
Debt Instrument [Line Items]
Interest rate at period end (as a percent)	2.87%								2.87%
Face amount of debt	$ 123,000,000								₩ 150
Proceeds from issuance of long-term debt	$ 123,000,000

Pension Plans - Components of N

Pension Plans - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Retirement Benefits [Abstract]
Service cost	$ 7,536	$ 7,977
Interest cost	1,247	1,324
Expected return on plan assets	(1,374)	(1,618)
Recognized actuarial gain	14	(94)
Net periodic pension cost	$ 7,423	$ 7,589

Pension Plans - Summary of Defi

Pension Plans - Summary of Defined Contribution Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Retirement Benefits [Abstract]
Defined contribution expense	$ 4,816	$ 4,405

Fair Value Measurements - Instr

Fair Value Measurements - Instruments Not Recorded on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 1,469,602	$ 1,517,631
Fair Value | Senior notes | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	488,701	576,875
Fair Value | Revolving credit facilities and term loans | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	980,901	940,756
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	1,513,022	1,450,234
Carrying Value | Senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	519,355	519,211
Carrying Value | Revolving credit facilities and term loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 993,667	$ 931,023

Restructuring and Other Exit _3

Restructuring and Other Exit Activities - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Restructuring Cost and Reserve [Line Items]
Charges	$ 1,919
Japan Consolidation Activities
Restructuring Cost and Reserve [Line Items]
Charges	$ 1,900

Restructuring and Other Exit _4

Restructuring and Other Exit Activities - Exit Activities (Details)	3 Months Ended
	Mar. 31, 2020USD ($)
Restructuring Reserve [Roll Forward]
Accrual, beginning balance	$ 2,641,000
Charges	1,919,000
Cash Payments	(3,442,000)
Non-cash Amounts	(15,000)
Accrual, ending balance	1,103,000
Total cumulative charges incurred to date	9,874,000
Estimated additional charges to be incurred	19,000,000
Facility and Other Exit Costs
Restructuring Reserve [Roll Forward]
Accrual, beginning balance	2,196,000
Charges	1,310,000
Cash Payments	(2,482,000)
Non-cash Amounts	(12,000)
Accrual, ending balance	1,012,000
Total cumulative charges incurred to date	5,809,000
Estimated additional charges to be incurred	11,000,000
Employee Separation Costs
Restructuring Reserve [Roll Forward]
Accrual, beginning balance	271,000
Charges	30,000
Cash Payments	(300,000)
Non-cash Amounts	(1,000)
Accrual, ending balance	0
Total cumulative charges incurred to date	2,740,000
Estimated additional charges to be incurred	5,000,000
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Accrual, beginning balance	174,000
Charges	579,000
Cash Payments	(660,000)
Non-cash Amounts	(2,000)
Accrual, ending balance	91,000
Total cumulative charges incurred to date	1,325,000
Estimated additional charges to be incurred	$ 3,000,000