Amkor Technology (AMKR) 10-K 16 Feb 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Feb. 09, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
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
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	AMKR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 3,067
Entity Common Stock, Shares Outstanding		245,892,019
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE: Portions of the registrant’s Proxy Statement relating to its 2024 Annual Meeting of Stockholders, to be filed subsequently, are incorporated by reference into Part III of this Report where indicated.
Entity Central Index Key	0001047127
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Phoenix, Arizona
Auditor Firm ID	238

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Net sales	$ 6,503,065	$ 7,091,585	$ 6,138,329
Cost of sales	5,559,912	5,761,598	4,912,775
Gross profit	943,153	1,329,987	1,225,554
Selling, general and administrative	295,393	283,372	296,084
Research and development	177,473	149,429	166,037
Total operating expenses	472,866	432,801	462,121
Operating income	470,287	897,186	763,433
Interest expense	59,000	58,563	51,508
Other (income) expense, net	(32,554)	(18,309)	(3,141)
Total other expense, net	26,446	40,254	48,367
Income before taxes	443,841	856,932	715,066
Income tax expense	81,710	89,890	69,459
Net income	362,131	767,042	645,607
Net income attributable to noncontrolling interests	(2,318)	(1,219)	(2,612)
Net income attributable to Amkor	$ 359,813	$ 765,823	$ 642,995
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 1.46	$ 3.13	$ 2.64
Diluted (in dollars per share)	$ 1.46	$ 3.11	$ 2.62
Shares used in computing per common share amounts:
Basic (in shares)	245,628	244,676	243,878
Diluted (in shares)	247,176	246,205	245,704

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 362,131	$ 767,042	$ 645,607
Other comprehensive income (loss), net of tax:
Adjustments to net unrealized gains (losses) on available-for-sale debt investments	1,785	(1,225)	(369)
Adjustments to unrealized components of defined benefit pension plans	1,685	8,604	9,834
Foreign currency translation	(3,819)	(10,658)	(16,757)
Total other comprehensive income (loss)	(349)	(3,279)	(7,292)
Comprehensive income	361,782	763,763	638,315
Comprehensive income attributable to noncontrolling interests	(2,318)	(1,219)	(2,612)
Comprehensive income attributable to Amkor	$ 359,464	$ 762,544	$ 635,703

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 1,119,818	$ 959,072
Short-term investments (amortized cost of $474,663 and $283,641, respectively)	474,869	281,964
Accounts receivable, net of allowances of $8,114 and $365, respectively	1,149,493	1,365,504
Inventories	393,128	629,576
Other current assets	58,502	65,123
Total current assets	3,195,810	3,301,239
Property, plant and equipment, net	3,299,445	3,135,614
Operating lease right of use assets	117,006	171,163
Goodwill	20,003	21,517
Restricted cash	799	3,334
Other assets	138,062	188,890
Total assets	6,771,125	6,821,757
Current liabilities:
Short-term borrowings and current portion of long-term debt	131,624	143,813
Trade accounts payable	754,453	899,164
Capital expenditures payable	106,368	146,602
Short-term operating lease liability	33,616	70,991
Accrued expenses	358,414	401,841
Total current liabilities	1,384,475	1,662,411
Long-term debt	1,071,832	1,088,521
Pension and severance obligations	87,133	93,540
Long-term operating lease liabilities	56,837	75,745
Other non-current liabilities	175,813	201,839
Total liabilities	2,776,090	3,122,056
Commitments and contingencies (Note 17)
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, 292,167 and 291,249 shares issued, and 245,888 and 245,091 shares outstanding, respectively	292	291
Additional paid-in capital	2,008,170	1,996,344
Retained earnings	2,159,831	1,874,644
Accumulated other comprehensive income (loss)	16,350	16,699
Treasury stock, at cost, 46,279 and 46,158 shares, respectively	(222,335)	(219,226)
Total Amkor stockholders’ equity	3,962,308	3,668,752
Noncontrolling interests in subsidiaries	32,727	30,949
Total equity	3,995,035	3,699,701
Total liabilities and equity	$ 6,771,125	$ 6,821,757

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Short-term investments, amortized cost	$ 474,663	$ 283,641
Allowance	$ 8,114	$ 365
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock designated Series A, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock designated Series A, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock designated Series A, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	292,167,000	291,249,000
Common stock, shares outstanding (in shares)	245,888,000	245,091,000
Treasury stock, shares (in shares)	46,279,000	46,158,000

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - 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, common stock (in shares) at Dec. 31, 2020			288,923
Balance at beginning of period at Dec. 31, 2020	$ 2,353,959	$ 2,325,699	$ 289	$ 1,953,378	$ 562,502	$ 27,270	$ (217,740)	$ 28,260
Balance at beginning of period, treasury stock (in shares) at Dec. 31, 2020							(46,094)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	645,607	642,995			642,995			2,612
Other comprehensive income (loss)	(7,292)	(7,292)				(7,292)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(57)
Treasury stock acquired through surrender of shares for tax withholding	(1,325)	(1,325)					$ (1,325)
Issuance of stock through share-based compensation plans (in shares)			1,543
Issuance of stock through share-based compensation plans	12,787	12,787	$ 1	12,786
Share-based compensation	10,970	10,970		10,970
Cash dividends declared	(41,558)	(41,558)			(41,558)
Subsidiary dividends to noncontrolling interests	(602)							(602)
Balance at end of period, common stock (in shares) at Dec. 31, 2021			290,466
Balance at end of period at Dec. 31, 2021	2,972,546	2,942,276	$ 290	1,977,134	1,163,939	19,978	$ (219,065)	30,270
Balance at end of period, treasury stock (in shares) at Dec. 31, 2021							(46,151)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	767,042	765,823			765,823			1,219
Other comprehensive income (loss)	(3,279)	(3,279)				(3,279)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(7)
Treasury stock acquired through surrender of shares for tax withholding	(161)	(161)					$ (161)
Issuance of stock through share-based compensation plans (in shares)			783
Issuance of stock through share-based compensation plans	5,649	5,649	$ 1	5,648
Share-based compensation	13,562	13,562		13,562
Cash dividends declared	(55,118)	(55,118)			(55,118)
Subsidiary dividends to noncontrolling interests	$ (540)							(540)
Balance at end of period, common stock (in shares) at Dec. 31, 2022	291,249		291,249
Balance at end of period at Dec. 31, 2022	$ 3,699,701	3,668,752	$ 291	1,996,344	1,874,644	16,699	$ (219,226)	30,949
Balance at end of period, treasury stock (in shares) at Dec. 31, 2022	(46,158)						(46,158)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 362,131	359,813			359,813			2,318
Other comprehensive income (loss)	(349)	(349)				(349)
Treasury stock acquired through surrender of shares for tax withholding (in shares)							(121)
Treasury stock acquired through surrender of shares for tax withholding	(3,109)	(3,109)					$ (3,109)
Issuance of stock through share-based compensation plans (in shares)			918
Issuance of stock through share-based compensation plans	3,550	3,550	$ 1	3,549
Share-based compensation	8,277	8,277		8,277
Cash dividends declared	(74,626)	(74,626)			(74,626)
Subsidiary dividends to noncontrolling interests	$ (540)							(540)
Balance at end of period, common stock (in shares) at Dec. 31, 2023	292,167		292,167
Balance at end of period at Dec. 31, 2023	$ 3,995,035	$ 3,962,308	$ 292	$ 2,008,170	$ 2,159,831	$ 16,350	$ (222,335)	$ 32,727
Balance at end of period, treasury stock (in shares) at Dec. 31, 2023	(46,279)						(46,279)

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Parenthetical) - $ / shares	1 Months Ended	12 Months Ended
	Nov. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.07875	$ 0.30375	$ 0.225	$ 0.17

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 362,131	$ 767,042	$ 645,607
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	631,508	612,702	563,582
Amortization of deferred debt issuance costs and premiums	3,523	3,247	2,508
Deferred income taxes	13,394	(11,623)	10,676
Gain on disposal of fixed assets, net	(2,200)	(2,807)	(1,446)
Share-based compensation	8,277	13,562	10,970
Other, net	16,660	(1,957)	13,752
Changes in assets and liabilities:
Accounts receivable	205,491	(103,990)	(298,854)
Inventories	233,797	(148,137)	(190,555)
Other current assets	2,673	(23,802)	5,335
Other assets	10,875	(34,835)	14,746
Trade accounts payable	(134,618)	86,574	215,646
Accrued expenses	(48,389)	(40,637)	108,283
Pension and severance obligations	(844)	(10,547)	(30,013)
Net operating lease ROU asset	50,650	(14,483)	(14,781)
Operating lease liabilities	(52,543)	1,574	16,293
Other non-current liabilities	(30,365)	6,873	49,546
Net cash provided by operating activities	1,270,020	1,098,756	1,121,295
Cash flows from investing activities:
Payments for property, plant and equipment	(749,467)	(908,294)	(779,779)
Proceeds from sale of property, plant and equipment	8,444	3,148	3,157
Proceeds from foreign exchange forward contracts	44,013	33,578	16,608
Payments for foreign exchange forward contracts	(75,786)	(104,703)	(69,835)
Payments for short-term investments	(657,583)	(438,803)	(414,208)
Proceeds from sale of short-term investments	94,242	33,972	87,273
Proceeds from maturities of short-term investments	379,344	370,924	204,679
Other investing activities	4,883	3,009	8,226
Net cash used in investing activities	(951,910)	(1,007,169)	(943,879)
Cash flows from financing activities:
Proceeds from revolving credit facilities	370,000	80,000	0
Payments of revolving credit facilities	(370,000)	(80,000)	0
Proceeds from short-term debt	20,712	29,711	15,514
Payments of short-term debt	(19,448)	(27,187)	(19,927)
Proceeds from issuance of long-term debt	168,335	366,386	353,587
Payments of long-term debt	(175,427)	(214,290)	(316,635)
Payments for debt issuance costs	(1,385)	(7,297)	(1,294)
Payments of finance lease obligations	(66,398)	(40,673)	(20,373)
Proceeds from issuance of stock through share-based compensation plans	3,562	5,635	12,787
Payments of dividends	(74,686)	(55,116)	(51,213)
Other financing activities	(4,472)	(1,572)	(2,548)
Net cash (used in) provided by financing activities	(149,207)	55,597	(30,102)
Effect of exchange rate fluctuations on cash, cash equivalents and restricted cash	(10,692)	(16,299)	(17,990)
Net increase in cash, cash equivalents and restricted cash	158,211	130,885	129,324
Cash, cash equivalents and restricted cash, beginning of period	962,406	831,521	702,197
Cash, cash equivalents and restricted cash, end of period	1,120,617	962,406	831,521
Cash paid during the period for:
Interest	54,306	54,355	46,932
Income taxes	90,458	97,333	24,011
Non-cash investing and financing activities:
Property, plant and equipment included in capital expenditures payable	104,109	142,160	211,421
Right of use assets acquired through operating lease liabilities	6,270	64,849	63,314
Right of use assets acquired through finance lease liabilities	58,232	58,166	73,894
Dividends declared and unpaid	$ 0	$ 25	$ 58

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Description of Business Amkor is one of the world’s leading providers of outsourced semiconductor packaging and test services. Amkor was a pioneer in the outsourcing of semiconductor packaging and test services, and over the years we have built a leading position by: • Designing and developing innovative packaging and test technologies focused on advanced packaging solutions in high growth markets, including artificial intelligence; • Building expertise in high-volume manufacturing processes and developing a reputation for high quality and solid execution; • Cultivating long-standing relationships with our customers, which include many of the world’s leading semiconductor companies; • Collaborating with customers, foundries, OEMs and equipment and material suppliers; • Focusing on strategic end markets that offer solid growth potential; • Providing a geographically diverse operating base with manufacturing facilities in multiple countries across Asia and in Europe; and • Developing a competitive cost structure through disciplined capital investment. Basis of Presentation Our Consolidated Financial Statements include the accounts of Amkor Technology, Inc. and its subsidiaries. Our Consolidated Financial Statements reflect the elimination of all significant inter-company accounts and transactions. Our investments in variable interest entities in which we are the primary beneficiary are consolidated. We reflect the remaining portion of variable interest entities and foreign subsidiaries that are not wholly owned as noncontrolling interests. The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, income taxes, inventory and long-lived assets. These estimates are based on management’s best knowledge of current events, historical experience, actions that we may undertake in the future and on various other assumptions that are believed to be reasonable under the circumstances. As a result, actual results could differ materially from these estimates and assumptions, including the impact of any deterioration in the global business and economic environment. Certain prior year amounts have been reclassified to conform to current year presentation. Consolidation of Variable Interest Entities We have variable interests in certain Philippine realty corporations in which we have a 40% ownership. We lease land and buildings in the Philippines from these entities and we are the primary beneficiary of these arrangements. As of December 31, 2023, the combined book value of the assets and liabilities associated with these Philippine realty corporations included in our Consolidated Balance Sheet was $17.3 million and $0.1 million, respectively. The impact of consolidating these variable interest entities on our Consolidated Statements of Income was not significant, and other than our lease payments, we have not provided any significant assistance or other financial support to these variable interest entities for the years ended December 31, 2023, 2022 or 2021. The creditors of the Philippine realty corporations have no recourse to our general credit. Foreign Currency Translation The U.S. dollar is the functional currency of our subsidiaries other than our Japan operations. The foreign currency asset and liability amounts at these subsidiaries are remeasured into U.S. dollars at end-of-period exchange rates, except for nonmonetary items which are remeasured at historical rates. Foreign currency income and expenses are remeasured at daily exchange rates, except for expenses related to balance sheet amounts which are remeasured at historical exchange rates. Exchange gains and losses arising from remeasurement of foreign currency-denominated monetary assets and liabilities are included in other (income) expense, net in the period in which they occur. The Japanese yen is the functional currency of our Japan operations. The asset and liability amounts of our Japan operations are translated into U.S. dollars at end-of-period exchange rates. Income and expenses are translated into U.S. dollars at the daily exchange rate. The resulting translation adjustments are reported as a component of accumulated other comprehensive income in the stockholders’ equity section of the balance sheet. Assets and liabilities denominated in a currency other than the functional currency are remeasured into the functional currency prior to translation into U.S. dollars, and the resulting transaction exchange gains or losses are included in other (income) expense, net in the period in which they occur. Risks and Concentrations The semiconductor industry is characterized by rapid technological change, competitive pricing pressures and cyclical market patterns. Our financial results are affected by a wide variety of factors, including general economic conditions worldwide, economic conditions specific to the semiconductor industry, the timely implementation of new package and test technologies, the ability to safeguard patents and intellectual property in a rapidly evolving market and reliance on materials and equipment suppliers. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns at various times. Our profitability and ability to generate cash from operations is principally dependent upon demand for semiconductors, the utilization of our capacity, semiconductor package mix, the average selling price of our services, our ability to manage our capital expenditures and our ability to control our costs including labor, material, overhead and financing costs. A significant portion of our revenues is concentrated with a small group of customers (Note 18). Direct sales to our largest customer accounted for 27.7% of our net sales for the year ended December 31, 2023. The loss of a significant customer, a business combination among customers, a reduction in orders or decrease in price from a significant customer or disruption in any of our significant strategic partnerships or other commercial arrangements could have a material adverse effect on our business, liquidity, results of operations, financial condition and cash flows. Financial instruments, for which we are subject to credit risk, consist principally of accounts receivable and cash, cash equivalents and short-term investments. With respect to accounts receivable, we mitigate our credit risk by selling primarily to well-established companies, performing ongoing credit evaluations and making frequent contact with customers. In addition, we may utilize non-recourse factoring to mitigate credit risk when considered appropriate. We have historically mitigated our credit risk with respect to cash and cash equivalents through diversification of our holdings into various high quality money market funds and bank deposit accounts. Our short-term investments are principally investments in debt securities with maximum duration of twenty-four months and range from AAA to BBB-rated financial instruments. Our short-term investments are primarily in corporate bonds, direct obligations of the U.S. Government or its agencies, asset-backed securities and commercial paper. At December 31, 2023, our cash and cash equivalents were primarily maintained in various U.S. and foreign bank operating and time deposit accounts and invested in various available-for-sale debt investments. See Note 6 for further discussion regarding our available-for-sale debt investments. Contingencies and Litigation We may be subject to certain legal proceedings, lawsuits and other claims, as discussed in Note 17. We accrue for a loss contingency, including legal proceedings, lawsuits, pending claims and other legal matters, when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, we accrue for the amount at the low end of the range. 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. Cash and Cash Equivalents We consider all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Our cash and cash equivalents are primarily maintained in various U.S. and foreign bank operating and time deposit accounts and invested in various available-for-sale debt investments. See Note 6 for further discussion regarding our available-for-sale debt investments. Restricted Cash Restricted cash, non-current, mainly consists of collateral to fulfill utility requirements. Investments Generally, we classify our short-term investments in fixed income securities as available-for-sale debt investments. All of our available-for-sale debt investments as of December 31, 2023 are available to fund current operations and are recorded at fair value (Note 6). 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. 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 in determining if and when a decline in value below the adjusted cost of our available-for-sale debt investments is an impairment. 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 impairment is considered based on condition (iii), the amount representing credit losses will be recognized in earnings and as an allowance for credit losses. The amount relating to all other factors will be recognized in other comprehensive income. Inventories Inventories consist of raw materials and purchased components and are stated at the lower of cost and net realizable value. Cost is principally determined by standard cost or the weighted moving average method, both of which approximate actual cost. We review and set our standard costs as needed, but at a minimum on a quarterly basis. We reduce the carrying value of our inventories for the cost of inventory we estimate is excess and obsolete based on the age of our inventories. When a determination is made that the inventory will not be utilized in production or is not saleable, it is written-off. Other Current Assets Other current assets consist principally of prepaid assets. Property, Plant and Equipment Property, plant and equipment are stated at cost. Depreciation is calculated by the straight-line method over the estimated useful lives of depreciable assets which are as follows: Buildings and improvements 10 to 40 years Machinery and equipment 2 to 7 years Software and computer equipment 3 to 5 years Furniture, fixtures and other equipment 4 to 10 years Cost and accumulated depreciation for property retired or disposed of are removed from the accounts, and any resulting gain or loss is included in earnings. Expenditures for maintenance and repairs are charged to expense as incurred. We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Recoverability of a long-lived asset group to be held and used in operations is measured by a comparison of the carrying amount to the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset group. If such asset group is considered to be impaired, the impairment loss is measured as the amount by which the carrying amount of the asset group exceeds its fair value. Long-lived assets to be disposed of are carried at the lower of cost or fair value less the costs of disposal. Leases We lease certain machinery and equipment, office space, and manufacturing facilities. Leases with an initial term of 12 months or less are not recorded on the balance sheet, and we recognize lease expense for these leases on a straight-line basis over the lease term. We combine lease components (e.g., fixed payments including rent, real estate taxes and insurance costs) with the non-lease components (e.g., common-area maintenance costs) for all asset classes. We use our incremental borrowing rate based on the information available at the lease commencement date to determine the lease liability. Our leases have remaining lease terms ranging from less than one year to 82 years. For purposes of calculating our lease liabilities, our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise those options. Certain leases also include options to purchase the leased property. Total long-term finance lease liabilities Goodwill Goodwill is recorded when the cost of an acquisition exceeds the fair value of the net tangible and identifiable intangible assets acquired. We review goodwill for impairment annually during the fourth quarter of each year and whenever events or changes in circumstances indicate that an impairment may exist. Impairment losses are recorded when the carrying amount of the reporting unit exceeds its fair value. The balance of goodwill in our Consolidated Balance Sheets reflects adjustments for foreign currency translation. Other Assets Other assets consist principally of deferred tax assets, refundable security deposits and advanced payments to vendors. Derivatives We use foreign exchange forward contracts, generally settled monthly, to manage a portion of our exposure to foreign exchange risk. The derivatives are recorded at the fair value either in other current assets or accrued expenses, with the associated gains and losses charged to other (income) expense, net See Note 15 for further discussion about the derivatives. Fair Value Measurements We apply fair value accounting for assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring or nonrecurring basis. We define fair value as the price that would be received from selling an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. See Note 16 for further discussion of fair value measurements. Revenue Recognition We recognize revenue, net of sales, use, value-added and other similar taxes, as a performance obligation is satisfied in an amount reflecting the consideration to which we expect to be entitled. We apply a five-step approach in determining the amount and timing of revenue to be recognized: (1) identifying the contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when the performance obligation is satisfied. Substantially all of our revenue is recognized as services are rendered. Our packaging and test services are our performance obligations to our customers. Our packaging services include wafer bump, probe and assembly. We provide packaging and test services to our customers either individually or as part of a combined offering. In a combined offering, we account for the individual services separately if they are determined to be distinct. We determine a service to be distinct if it is separately identifiable from other services in the combined offering and if a customer can benefit from the unique service on its own or with other resources that are readily available to the customer. The consideration, including variable consideration, is allocated between the distinct services in a combined offering based upon the stand-alone selling prices of the individual services. Our services involve a high degree of specialization which are unique based on the design and purpose of the customer’s wafers. Accordingly, our negotiated pricing reflects the customized nature of our services and represents a customer-specific stand-alone selling price. We recognize revenue as services are rendered, which generally occurs over the course of two to three weeks. Services are generally billed at completion of each individual packaging or test service or in some instances at the completion of all services in a combined offering. We recognize revenue over time as services are rendered because our services create or enhance the customer’s wafer. We utilize an input method (cost incurred plus estimated margin) to determine the amount of revenue to recognize for in-process, but incomplete, customer orders at a reporting date. During the period of providing our services, we generally do not control or take ownership of customers’ wafers, nor do we include the cost of the wafer in our cost calculations. We believe that a cost-based input method is the most appropriate manner to measure how we satisfy our performance obligations to customers because the effort and costs incurred to package and/or test customer wafers are not linear over the duration of these services. Shipping and handling costs are accounted for as a cost to fulfill our performance obligations to customers. Accordingly, we record customer payments of shipping and handling costs as a component of net sales, and the costs incurred for shipping and handling are then charged to cost of sales. Unbilled receivables are revenues that have been recognized for performance obligations that have been satisfied, or partially satisfied, in advance of billing the customer. Revenue may be recognized in advance of billing as our contracts provide us with an unconditional right to consideration for work that is performed. Total unbilled receivables as of December 31, 2023 and 2022 were $260.8 million and $301.7 million, respectively. These amounts are included in accounts receivable, net of allowances in our Consolidated Balance Sheets. At times, the company receives cash payments from customers in advance of the company’s performance. In such cases, we record deferred revenue until the performance obligation is satisfied, which represents a contract liability and is included in accrued expenses and other non-current liabilities in the consolidated balance sheets. These contract liabilities are classified as either current or long-term based on the timing of when the company expects to recognize revenue. Contract liabilities were $135.5 million and $170.6 million as of December 31, 2023 and December 31, 2022, respectively. As of December 31, 2023 and December 31, 2022, the short-term portion of the liability was $71.1 million and $81.5 million, respectively. The remainder of the December 31, 2023 contract liability balance is expected to be recognized in revenue over the next 1-5 years. Revenue recognized during the year that was included in the contract liability balance at the beginning of the period was $66.9 million, $101.2 million, and $29.0 million, for 2023, 2022 and 2021, respectively. Research and Development Costs Research and development expenses include costs attributable to the conduct of research and development programs primarily related to the development of new package designs or technologies and improving the efficiency and capabilities of our existing production processes. Such costs include labor, materials, supplies, depreciation and maintenance of research equipment, services provided by outside contractors and the allocable portions of facility costs such as rent, utilities, insurance, repairs and maintenance, depreciation and general support services. Costs associated with research and development are expensed as incurred. Income Taxes Income taxes are accounted for using the asset and liability method. Under this method, deferred income tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis as well as for net operating loss and tax credit carryforwards. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is provided for those deferred tax assets for which it is more likely than not that the related tax benefits will not be realized. 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 recent results of operations. With the exception of a certain foreign jurisdiction and select U.S. and foreign carryforwards, we consider it more likely than not that we will have sufficient taxable income to allow us to realize these deferred tax assets. However, in the event taxable income falls short of current expectations, we may need to establish a valuation allowance against such deferred tax assets. We recognize in our Consolidated Financial Statements the impact of an income tax position, if that position is more likely than not of being sustained on audit, based on the technical merits of the position. Related interest and penalties are classified as income taxes in the financial statements. See Note 4 for further discussion regarding unrecognized income tax benefits. Recently Issued Standards In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires disclosure of additional income tax information, primarily related to effective tax rate reconciliation and income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. Adoption of this ASU should be applied on a prospective basis, but retrospective application is permitted. We are currently evaluating the impact of this new standard on our financial statements, which is expected to result in enhanced disclosures.

Share-Based Compensation Plans

Share-Based Compensation Plans	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Share-Based Compensation Plans	Share-Based Compensation Plans For the years ended December 31, 2023, 2022 and 2021, we recognized share-based compensation of $8.3 million, $13.6 million and $11.0 million, respectively, primarily in selling, general and administrative expenses. The amount of compensation expense to be recognized is adjusted for an estimated forfeiture rate which is based on historical data. The corresponding deferred income tax benefits are $0.7 million, $1.7 million and $1.4 million for 2023, 2022 and 2021, respectively. Equity Incentive Plans Second Amended and Restated 2007 Equity Incentive Plan. The Second Amended and Restated 2007 Equity Incentive Plan (as amended, the “2007 Plan”) provided for the grant of the following types of incentive awards: (i) stock options; (ii) restricted stock; (iii) restricted stock units; (iv) stock appreciation rights; (v) performance units and performance shares; and (vi) other stock or cash awards. Those eligible for awards included employees, directors and consultants who provide services to Amkor and its subsidiaries. There were originally 17.0 million shares of our common stock reserved for issuance under the 2007 Plan. No awards have been or will be granted under the 2007 Plan after the effective date of the 2021 Plan (as defined below), but all outstanding awards under the 2007 Plan will continue in full force and effect, subject to their original terms. 2021 Equity Incentive Plan. On May 18, 2021, at our 2021 Annual Meeting of Stockholders (the “2021 Annual Meeting”), our stockholders approved the Amkor Technology, Inc. 2021 Equity Incentive Plan (as amended, the “2021 Plan”) to replace the 2007 Plan. The 2021 Plan provides for the grant of the following types of incentive awards: (i) stock options; (ii) restricted stock; (iii) restricted stock units; (iv) stock appreciation rights; (v) performance units and performance shares; and (vi) other stock or cash awards. Those eligible for awards include employees, directors and consultants who provide services to Amkor and its subsidiaries. The number of shares authorized and available for issuance under the 2021 Plan is 23,100,000 shares, reduced for certain awards granted under the 2007 Plan after December 31, 2020, but before May 18, 2021. There were originally 22.8 million shares of our common stock reserved for issuance under the 2021 Plan, and at December 31, 2023, there were 20.6 million shares available for grant under the 2021 Plan. Stock options Stock options are generally granted with an exercise price equal to the market price of the stock at the date of grant. Substantially all of the options granted are exercisable pursuant to a one In order to calculate the fair value of stock options at the date of grant, we use the Black-Scholes option pricing model. Expected volatilities are based on historical performance of our stock. We also use historical data to estimate the timing and amount of option exercises and forfeitures within the valuation model. The expected term of the options is based on evaluations of historical and expected future employee exercise behavior and represents the period of time that options granted are expected to be outstanding. The risk-free interest rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant. The dividend yield is based on the annualized declared quarterly dividend rate divided by our closing stock price at the date of the grant. The following table summarizes our stock option activity for the year ended December 31, 2023: Number of Weighted-Average Weighted-Average Aggregate Outstanding at December 31, 2022 2,376 $ 10.54 Granted — — Exercised (345) 10.31 Forfeited or expired — — Outstanding at December 31, 2023 2,031 $ 10.58 4.98 years $ 46,068 Fully vested at December 31, 2023 and expected to vest thereafter 2,029 $ 10.58 4.98 years $ 46,029 Exercisable at December 31, 2023 1,973 $ 10.51 4.93 years $ 44,903 Total unrecognized compensation expense from stock options was $0.3 million as of December 31, 2023, which is expected to be recognized over a weighted-average period of approximately 0.79 years beginning January 1, 2024. The total intrinsic value of options exercised during fiscal years 2023, 2022, and 2021 was $5.8 million, $8.0 million, and $17.7 million, respectively. Restricted shares Restricted shares granted to our non-employee directors vest on the earlier of the one year anniversary of the grant date or the date of the annual meeting of stockholders immediately following the grant date, subject to the recipient’s continued service as a director of Amkor on the applicable vesting date. Generally, other restricted shares vest ratably over three years, with 8.33% of the shares vesting in equal quarterly installments such that 100% of the shares will become vested on the third anniversary of the award, subject to the recipient’s continued employment with us on the applicable vesting date. In addition, provided that the restricted shares have not been forfeited earlier, under the terms and conditions of the applicable award agreements for certain grants, the restricted shares will vest upon the recipient’s death or disability, or upon a change in control of Amkor. The value of the restricted shares is determined based on the fair market value of the underlying shares on the date of the grant and is recognized ratably over the vesting period. The following table summarizes our restricted share activity for the year ended December 31, 2023: Number of Weighted- average Non-vested at December 31, 2022 109 $ 15.38 Awards granted — — Awards vested (109) 15.38 Awards forfeited — — Non-vested at December 31, 2023 — $ — For the year ended December 31, 2023, the total fair value of our vested restricted shares was $2.9 million, respectively. Restricted stock units From time to time, and pursuant to the 2021 Plan, we grant time-vested restricted stock units (“RSUs”) to our non-employee directors and certain employees and performance-vested restricted stock units (“PSUs”) to certain employees. RSUs generally vest in four equal installments over a four-year period such that 100% of the RSUs will become vested on the fourth anniversary of the award, subject to the recipient’s continued employment with us on the applicable vesting dates. In some circumstances, we have granted RSUs subject to different vesting conditions, including RSUs that vest in full in a single installment. Provided that the RSUs have not been forfeited earlier, they will generally vest upon the recipient’s retirement, death or disability, or upon a change in control of Amkor, in accordance with the terms and conditions of the applicable award agreement. The value of the RSUs is determined based on the fair market value of the underlying shares on the date of the grant, reduced by the present value of dividends or dividend equivalent rights expected to be paid on our common stock prior to vesting, and is recognized ratably over the vesting period. PSUs generally vest in one installment after a two-year period such that any earned PSUs will become vested within 90 days of the second anniversary of the award, subject to the recipient’s continued employment with us on the applicable vesting date. Generally for PSUs, the number of shares of our common stock to be received at vesting will range from 0% to 200% of the target grant amount based on Cumulative Basic EPS (as defined in the applicable award agreement) over a two-year performance measurement period. In some circumstances, we have granted PSUs subject to different vesting conditions, including PSUs that vest in full upon the achievement of performance goals other than Cumulative Basic EPS. Provided the PSUs have not been forfeited earlier, the PSUs will generally vest upon the recipient’s retirement, death or disability, or upon a change of control of Amkor, in accordance with the terms and conditions of the applicable award agreement. The value of the PSUs is initially determined based on the fair market value of the underlying shares on the date of the grant, reduced by the present value of dividends expected to be paid on our common stock prior to vesting, and is recognized over the vesting period. The following table summarizes our RSU and PSU activity: Number of Weighted- average Non-vested at December 31, 2020 — $ — Awards granted 295 22.48 Awards vested — — Awards forfeited (9) 22.58 Non-vested at December 31, 2021 286 22.48 Awards granted 531 22.29 Awards vested (22) 22.23 Awards forfeited (57) 22.63 Non-vested at December 31, 2022 738 22.34 Awards granted 1,049 26.72 Awards vested (464) 22.19 Awards forfeited (16) 25.24 Non-vested at December 31, 2023 1,307 $ 25.87 Total unrecognized compensation expense from RSUs and PSUs was $12.1 million as of December 31, 2023, which is expected to be recognized over a weighted-average period of approximately 1.3 years beginning January 1, 2024. For the years ended December 31, 2023 and 2022, the total fair value of our vested RSUs and PSUs were $11.6 million and $0.5 million, respectively.

Other Income and Expense

Other Income and Expense	12 Months Ended
	Dec. 31, 2023
Other Income and Expenses [Abstract]
Other Income and Expense	Other Income and Expense Other income and expense consists of the following: For the Year Ended December 31, 2023 2022 2021 (In thousands) Interest income $ (48,458) $ (12,762) $ (1,065) Foreign currency (gain) loss, net 18,361 (1,572) 723 Loss on debt retirement — 464 — Other (2,457) (4,439) (2,799) Total other (income) expense, net $ (32,554) $ (18,309) $ (3,141)

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Geographic sources of income (loss) before taxes are as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) United States $ 94,643 $ 81,488 $ 81,994 Foreign 349,198 775,444 633,072 Income before taxes $ 443,841 $ 856,932 $ 715,066 The components of the provision (benefit) for income taxes are as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Current: Federal $ 19,831 $ 40,063 $ 9,649 State 7 150 198 Foreign 48,478 61,300 48,936 68,316 101,513 58,783 Deferred: Federal 8,899 (10,156) 20,478 State 1 1,458 361 Foreign 4,494 (2,925) (10,163) 13,394 (11,623) 10,676 Income tax expense $ 81,710 $ 89,890 $ 69,459 The reconciliation between the U.S. federal statutory income tax rate of 21% and our effective tax rate is as follows: For the Year Ended December 31, 2023 2022 2021 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % Foreign income taxed at different rates (4.2) (12.0) (9.5) Foreign exchange (loss) gain 0.5 2.2 (2.3) Change in valuation allowance 2.9 (2.4) 0.1 Income tax credits generated (7.5) (6.1) (5.1) Foreign earnings and profits 7.0 9.0 5.7 Foreign derived intangible income (1.6) (0.9) (1.1) Settlements and changes in uncertain tax positions (0.5) (0.2) 0.8 Other 0.8 (0.1) 0.1 Income tax expense 18.4 % 10.5 % 9.7 % In 2022, we reversed $17.8 million of valuation allowance recorded against U.S. foreign tax credit carryforwards previously projected to expire unused due to the limitations to utilize the credits under current tax law. Realization of these carryforwards is dependent on generating sufficient taxable income to overcome the foreign tax credit limitation provisions. Although utilization of these carryforwards is not assured, in light of our current earnings and recent estimates of future taxable income, management believes sufficient positive evidence exists to conclude that the respective valuation allowances are no longer needed, resulting in the reversal of these valuation allowances. As a result of certain capital investments, export commitments and employment levels, income from operations in Korea, the Philippines and Singapore was subject to reduced income tax rates and, in some cases, was exempt from income taxes. The most significant tax rate impact is in Singapore where we have been granted a conditional reduced tax rate that expires at the end of 2028. We recognized $18.6 million, $84.5 million and $56.7 million in tax benefits as a result of the conditional reduced tax rates in 2023, 2022 and 2021, respectively. The benefit of the conditional reduced tax rates on diluted earnings per share was approximately $0.08, $0.34 and $0.23 for 2023, 2022 and 2021, respectively. The following is a summary of the components of our deferred tax assets and liabilities: December 31, 2023 2022 (In thousands) Deferred tax assets: Net operating loss carryforwards $ 33,679 $ 49,846 Tax credit carryforwards 88,147 92,368 Property, plant and equipment 21,387 15,328 Deferred interest expense 476 — Accrued liabilities 37,832 39,929 Receivable 30,086 29,178 Unrealized foreign exchange loss 7,205 8,018 Revenue recognition — 1,564 Operating lease liabilities 16,053 26,955 Other 15,219 14,665 Total deferred tax assets 250,084 277,851 Valuation allowance (114,811) (101,869) Total deferred tax assets net of valuation allowance 135,273 175,982 Deferred tax liabilities: Property, plant and equipment 34,206 50,215 Deferred gain 5,739 7,839 Unrealized foreign exchange gain 3,129 5,242 Unbilled receivables 8,995 822 Operating lease right of use assets 16,031 26,241 Other 5,533 7,433 Total deferred tax liabilities 73,633 97,792 Net deferred tax assets $ 61,640 $ 78,190 Recognized as: Other assets $ 73,585 $ 86,616 Other non-current liabilities (11,945) (8,426) Total $ 61,640 $ 78,190 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 recent results of operations. Valuation allowance against deferred tax assets consist of the following: December 31, 2023 2022 (In thousands) Valuation allowance: U.S. $ 44,426 $ 40,610 Foreign 70,385 61,259 Total valuation allowance $ 114,811 $ 101,869 Our net operating loss carryforwards are as follows: December 31, 2023 2022 Expiration (In thousands) U.S. federal net operating loss carryforwards $ 5,611 $ 13,003 2024 U.S. state net operating loss carryforwards 32,612 38,384 2024-2036 Foreign net operating loss carryforwards 196,636 240,740 2027-2031 At December 31, 2023 and 2022, a portion of our remaining U.S. federal net operating loss carryforwards was reserved with a valuation allowance due to ownership change limitations from a prior year acquisition as well as certain state net operating loss carryforwards expected to expire unused. Also, we have a valuation allowance against foreign net operating loss carryforwards that we do not expect to have sufficient taxable income to realize as of December 31, 2023 and 2022. Our tax credit carryforwards are as follows: December 31, 2023 2022 Expiration (In thousands) U.S. Foreign Tax Credits $ 51,512 $ 54,130 2027-2033 U.S. Other Tax Credits 2,559 110 2026-2033 Foreign Tax Credits 34,546 38,128 2024-2033 At December 31, 2023 and 2022, a portion of our U.S. and foreign tax credit carryforwards were reserved with a valuation allowance for the amount expected to expire unused. Distributions of cash to the U.S. as dividends generally will not be subject to U.S. federal income tax. We have not provided foreign withholding taxes or state income taxes on the undistributed earnings of our foreign subsidiaries, over which we have sufficient influence to control the distribution of such earnings and have determined that substantially all such earnings have been reinvested indefinitely. These earnings could become subject to foreign withholding tax if they are remitted as dividends. For the year ended December 31, 2023, we estimate that repatriation of these foreign earnings would generate withholding taxes and state income taxes of approximately $165.9 million. We operate in and file income tax returns in various U.S. and foreign jurisdictions which are subject to examination by tax authorities. We have tax returns that are open to examination in various jurisdictions for tax years 2013-2023. 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 examinations will be favorable. Our unrecognized tax benefits are subject to change as examinations of specific tax years are completed in the respective jurisdictions. In certain circumstances where we elect to appeal the results of an examination, we may be required to make tax assessment payments to proceed with the administrative appeal process. Current examinations include 2019-2022 Korean income tax returns, 2017-2021 Malaysia income tax returns and 2021 Philippine income tax return. A reconciliation of the beginning and ending gross amount of unrecognized tax benefits is as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Balance at January 1 $ 33,253 $ 37,293 $ 32,598 Additions based on tax positions related to the current year — 1,519 9,562 Additions for tax positions of prior years 495 1,909 1,740 Reductions for tax positions of prior years (345) (5,755) (66) Reductions related to settlements with tax authorities — (988) (1,266) Reductions from lapse of statutes of limitations (1,866) (725) (5,275) Balance at December 31 $ 31,537 $ 33,253 $ 37,293 The net decrease in our unrecognized tax benefits was $1.7 million from December 31, 2022 to December 31, 2023. The decrease was primarily related to the lapse of statutes of limitations. At December 31, 2023, all of our gross unrecognized tax benefits would reduce our effective tax rate, if recognized. It is reasonably possible that unrecognized tax benefits related to income attribution will decrease in the next 12 months by up to $0.8 million due to the lapse of statutes of limitations in foreign jurisdictions. The liability related to our unrecognized tax benefits, before interest and penalties, is $23.0 million as of December 31, 2023 and is reported as a component of other non-current liabilities. The unrecognized tax benefits presented in the table above also include positions that have reduced deferred tax assets by $8.5 million. The balance of accrued and unpaid interest and penalties is $4.5 million and $4.9 million as of December 31, 2023 and 2022, respectively, and is included as a component of other non-current liabilities in connection with our unrecognized tax benefits.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2023
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, PSUs, RSUs and unvested restricted shares. The following table summarizes the computations of basic and diluted EPS: For the Year Ended December 31, 2023 2022 2021 (In thousands, except per share data) Net income attributable to Amkor common stockholders $ 359,813 $ 765,823 $ 642,995 Weighted-average number of common shares outstanding — basic 245,628 244,676 243,878 Effect of dilutive securities: Share-based awards 1,548 1,529 1,826 Weighted-average number of common shares outstanding — diluted 247,176 246,205 245,704 Net income attributable to Amkor per common share: Basic $ 1.46 $ 3.13 $ 2.64 Diluted $ 1.46 $ 3.11 $ 2.62 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 Year Ended December 31, 2023 2022 2021 (In thousands) Share-based awards 2 180 112

Investments

Investments	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The following table summarizes our cash equivalents and available-for-sale debt investments: December 31, 2023 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Asset-backed securities $ 138 $ — $ — $ 138 $ — $ 138 Commercial paper 48,063 — — 48,063 — 48,063 Money market funds 60,719 — — 60,719 60,719 — U.S. government bonds 2,996 — — 2,996 2,996 — Total cash equivalents (2) 111,916 — — 111,916 63,715 48,201 Short-term investments Asset-backed securities 65,340 170 (22) 65,488 — 65,488 Certificate of deposits 17,086 — — 17,086 17,086 — Commercial paper 56,273 — — 56,273 — 56,273 Corporate bonds 251,671 432 (299) 251,804 — 251,804 U.S. government agency bonds 13,200 — (9) 13,191 — 13,191 U.S. government bonds 65,881 13 (79) 65,815 65,815 — Total short-term investments 469,451 615 (409) 469,657 82,901 386,756 Total $ 581,367 $ 615 $ (409) $ 581,573 $ 146,616 $ 434,957 December 31, 2022 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Asset-backed securities $ 25 $ — $ — $ 25 $ — $ 25 Commercial paper 69,101 — — 69,101 — 69,101 Money market funds 97,650 — — 97,650 97,650 — Municipal bonds 1,001 — — 1,001 — 1,001 US government bonds 10,767 1 — 10,768 10,768 — US government agency bonds 16,982 3 — 16,985 — 16,985 Total cash equivalents (2) 195,526 4 — 195,530 108,418 87,112 Short-term investments Asset-backed securities 25,677 7 (134) 25,550 — 25,550 Certificate of deposits 17,362 — — 17,362 17,362 — Commercial paper 27,866 — — 27,866 — 27,866 Corporate bonds 198,868 7 (1,529) 197,346 — 197,346 Foreign government bonds 996 — (4) 992 — 992 Mortgage-backed securities 696 — (2) 694 — 694 Municipal bonds 364 — (2) 362 — 362 U.S. government agency bonds 735 — (1) 734 — 734 U.S. government bonds 6,704 1 (20) 6,685 6,685 — Total short-term investments 279,268 15 (1,692) 277,591 24,047 253,544 Total $ 474,794 $ 19 $ (1,692) $ 473,121 $ 132,465 $ 340,656 (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 we do not believe it is more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) During the years ended December 31, 2023, 2022, and 2021 we sold cash equivalent investments for proceeds of $47.0 million, $29.6 million and $12.8 million, respectively, and realized no gain or loss on such sales. The following table summarizes the contractual maturities of our cash equivalents and available-for-sale debt investments as of December 31, 2023: Amortized Cost Fair Value Within 1 year $ 406,551 $ 406,346 After 1 year through 5 years 109,338 109,601 Asset-backed securities 65,478 65,626 Total $ 581,367 $ 581,573 Actual maturities can differ from contractual maturities due to various factors including whether the issuers 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. As of December 31, 2023, the amortized cost and fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $5.2 million. As of December 31, 2022 the amortized cost and fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $4.4 million and $4.3 million, respectively.

Factoring of Accounts Receivabl

Factoring of Accounts Receivable	12 Months Ended
	Dec. 31, 2023
Factoring of Accounts Receivable [Abstract]
Factoring of Accounts Receivable	Factoring of Accounts ReceivableFor certain accounts receivable, we use non-recourse factoring arrangements with third-party financial institutions to manage our working capital and cash flows. Under these arrangements, 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 years ended December 31, 2023 and 2022, we sold accounts receivable totaling $253.9 million and $386.5 million, net of discounts and fees of $1.3 million and $1.1 million, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consist of the following: December 31, 2023 2022 (In thousands) Land $ 212,722 $ 214,763 Buildings and improvements 2,080,589 1,817,135 Machinery and equipment 7,022,614 6,757,652 Finance lease assets 209,506 165,122 Furniture, fixtures and other equipment 22,655 23,240 Software and computer equipment 200,362 240,610 Construction in progress 223,332 152,809 Total property, plant and equipment 9,971,780 9,371,331 Accumulated depreciation and amortization (6,672,335) (6,235,717) Total property, plant and equipment, net $ 3,299,445 $ 3,135,614 The following table summarizes our depreciation expense: For the Year Ended December 31, 2023 2022 2021 (In thousands) Depreciation expense $ 630,941 $ 612,105 $ 562,962 In October 2023, we completed the first phase of construction for our Vietnam Facility and transferred $244.3 million from construction in progress to buildings and improvements.

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	Leases The components of lease expense were as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Operating lease cost $ 70,722 $ 81,410 $ 64,902 Finance lease cost Amortization of leased assets 42,345 24,644 14,196 Interest on lease liabilities 5,521 3,891 2,768 Total finance lease cost 47,866 28,535 16,964 Short-term lease cost 4,788 5,749 6,264 Variable lease cost 6,921 6,592 7,409 Net lease cost $ 130,297 $ 122,286 $ 95,539 Other information related to leases was as follows: For the Year Ended December 31, 2023 2022 2021 Supplemental Cash Flows Information (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 73,774 $ 81,044 $ 64,786 Operating cash flows for finance leases 5,419 3,933 1,745 Financing cash flows for finance leases 66,398 40,673 20,373 Weighted Average Remaining Lease Term (years) Operating leases 6.1 4.2 3.2 Finance leases 3.2 2.3 3.1 Weighted Average Discount Rate Operating leases 5.2 % 4.4 % 3.6 % Finance leases 5.7 % 4.1 % 3.2 % Maturities of lease liabilities were as follows: December 31, 2023 Operating Leases Finance Leases (In thousands) 2024 $ 36,916 $ 62,306 2025 19,869 25,259 2026 12,752 11,436 2027 9,144 3,568 2028 6,017 2,511 Thereafter 20,488 12,913 Total future minimum lease payments 105,186 117,993 Less: Imputed interest (14,733) (12,438) Total $ 90,453 $ 105,555 As of December 31, 2023, we have entered into additional lease agreements that have not yet commenced of approximately $8 million.
Leases	Leases The components of lease expense were as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Operating lease cost $ 70,722 $ 81,410 $ 64,902 Finance lease cost Amortization of leased assets 42,345 24,644 14,196 Interest on lease liabilities 5,521 3,891 2,768 Total finance lease cost 47,866 28,535 16,964 Short-term lease cost 4,788 5,749 6,264 Variable lease cost 6,921 6,592 7,409 Net lease cost $ 130,297 $ 122,286 $ 95,539 Other information related to leases was as follows: For the Year Ended December 31, 2023 2022 2021 Supplemental Cash Flows Information (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 73,774 $ 81,044 $ 64,786 Operating cash flows for finance leases 5,419 3,933 1,745 Financing cash flows for finance leases 66,398 40,673 20,373 Weighted Average Remaining Lease Term (years) Operating leases 6.1 4.2 3.2 Finance leases 3.2 2.3 3.1 Weighted Average Discount Rate Operating leases 5.2 % 4.4 % 3.6 % Finance leases 5.7 % 4.1 % 3.2 % Maturities of lease liabilities were as follows: December 31, 2023 Operating Leases Finance Leases (In thousands) 2024 $ 36,916 $ 62,306 2025 19,869 25,259 2026 12,752 11,436 2027 9,144 3,568 2028 6,017 2,511 Thereafter 20,488 12,913 Total future minimum lease payments 105,186 117,993 Less: Imputed interest (14,733) (12,438) Total $ 90,453 $ 105,555 As of December 31, 2023, we have entered into additional lease agreements that have not yet commenced of approximately $8 million.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following: December 31, 2023 2022 (In thousands) Payroll and benefits $ 115,604 $ 137,445 Deferred revenue and customer advances 71,117 81,459 Short-term finance lease liability 57,761 56,570 Income taxes payable 35,215 50,685 Accrued interest 11,175 10,878 Accrued severance plan obligations (Note 12) 7,906 7,422 Other accrued expenses 59,636 57,382 Total accrued expenses $ 358,414 $ 401,841

Debt

Debt	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt	Debt Short-term borrowings and long-term debt consist of the following: December 31, 2023 2022 (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.: Term loan, fixed rate at 1.85%, due April 2024 (1) — — Term loan, fixed rate at 2.12%, due December 2028 200,000 200,000 Amkor Technology Japan, Inc.: Short-term term loans, variable rate (2) 5,098 4,042 Term loan, fixed rate at 1.30%, due July 2023 — 29,744 Term loan, fixed rate at 1.35%, due December 2024 40,414 86,943 Term loan, fixed rate at 1.20%, due December 2025 30,913 49,878 Term loan, fixed rate at 1.23%, due December 2026 55,729 79,927 Term loan, fixed rate at 1.59%, due December 2027 89,053 119,738 Term loan, fixed rate at 1.80%, due December 2028 (3) 124,078 — Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loans, SOFR plus 0.75%, due March 2024 (4) — 46,000 Term loans, SOFR plus 0.75%, due June 2025 (4) 37,000 39,000 Term loans, SOFR plus 0.75%, due 2025 (4) 57,500 59,500 Term loans, SOFR plus 1.40%, due December 2026 (5) 45,000 — Other: Credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) (6) — — Senior secured revolving credit facility, applicable bank rate plus 1.75%, due March 2027 (Singapore) (7) — — 1,209,785 1,239,772 Less: Unamortized discount and deferred debt costs, net (6,329) (7,438) Less: Short-term borrowings and current portion of long-term debt (131,624) (143,813) Long-term debt $ 1,071,832 $ 1,088,521 (1) In April 2021, we entered into a ₩80 billion term loan agreement with the option to borrow and re-borrow the funds up to six times per year through April 2024. Principal is payable at maturity, and interest is payable monthly. As of December 31, 2023, ₩80.0 billion, or approximately $62 million, was available to be drawn. (2) We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. As of December 31, 2023, $7.7 million was available to be drawn. (3) In December 2023, we borrowed ¥17.5 billion (US$123.3 million) under a new term loan agreement due December 2028, guaranteed by Amkor Technology, Inc. and our subsidiary, ATSH. Principal is due in 20 equal, quarterly installments plus accrued interest, through maturity. (4) In June 2023, Amkor Assembly & Test (Shanghai) Co. Ltd. amended all term loans to replace London Interbank Offered Rate (“LIBOR”) with a Secured Overnight Financing Rate (“SOFR”) plus 0.75% annual base rate. This contractual amendment is treated as a modification with no recognized gain or loss. (5) In December 2023, we entered into a $45.0 million term loan. Principal is payable in semiannual installments of $0.5 million, with the remaining balance due at maturity. Interest is payable quarterly. (6) In March 2022, ATT amended an existing revolving credit facility to reduce the availability from $36.0 million to $15.0 million. As of December 31, 2023, $15.0 million was available for future borrowings under such credit facility. (7) In March 2022, ATSH entered into the 2022 Singapore Revolver, which is guaranteed by Amkor Technology, Inc., ATT and AATT. The maximum borrowing capacity under the 2022 Singapore Revolver is limited to a base amount equal to the lesser of: (1) $600.0 million; or (2) $250.0 million plus a variable amount equal to 37.5% of our consolidated accounts receivable balance. As of December 31, 2023, $600.0 million was available for future borrowings under the 2022 Singapore Revolver. Certain of our foreign debt is collateralized by the land, buildings, equipment and accounts receivable in the respective locations. As of December 31, 2023 the collateralized debt balance was $679.7 million, of which $326.5 million of assets were pledged as collateral. Interest Rates Interest is payable semiannually on our senior notes and quarterly or monthly on our other fixed- and variable-rate debt. Refer to the table above for the interest rates on our fixed-rate debt and to the table below for the interest rates on our variable-rate debt. December 31, 2023 2022 Amkor Technology Japan, Inc: Short-term term loans, variable rate 0.24 % 0.29 % Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loans, SOFR plus 0.75% due March 2024 — 5.83 % Term loans, SOFR plus 0.75% due June 2025 6.07 % 5.55 % Term loans, SOFR plus 0.75%, due 2025 6.07 % 5.48 % Term loans, SOFR plus 1.40%, due December 2026 6.76 % — Compliance with Debt Covenants 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., ATT, AATT and ATSH 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. These restrictions are determined in part by calculations based upon cumulative net income and do not currently have a material impact on our ability to make dividend payments or stock repurchases. We were in compliance with all debt covenants at December 31, 2023 and 2022. Maturities Total Debt (In thousands) Payments due for the year ending December 31, 2024 $ 131,624 2025 222,612 2026 158,655 2027 622,079 2028 74,815 Thereafter — Total debt $ 1,209,785

Pension and Severance Plans

Pension and Severance Plans	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Pension and Severance Plans	Pension and Severance Plans Korean Severance Plan Our subsidiary in Korea maintains an unfunded severance plan that covers certain employees that were employed prior to August 1, 2015. To the extent eligible employees are terminated, our subsidiary in Korea would be required to make lump-sum severance payments on behalf of these eligible employees for service provided prior to August 1, 2015. Factors used to determine severance benefits include employees’ length of service, seniority and rate of pay. The employees’ length of service and seniority are fixed as of July 31, 2015. The employees’ rate of pay is adjusted to the rate of pay at the time of termination. Accrued severance benefits are estimated assuming all eligible employees were to terminate their employment at the balance sheet date. Our contributions to the National Pension Plan of the Republic of Korea are deducted from accrued severance benefit liabilities. On August 1, 2015, our subsidiary in Korea began sponsoring a defined benefit pension plan and a defined contribution plan. Existing employees at that time were given the option of choosing either a defined benefit pension plan or a defined contribution plan for their future benefits and new employees since that date are enrolled in a defined contribution plan. The changes to the balance of our accrued severance plan obligations are as follows: For the Year Ended December 31, 2023 2022 (In thousands) Balance at January 1 $ 56,289 $ 73,345 Provision of severance benefits 1,653 2,119 Severance payments (8,770) (15,295) Foreign currency (gain) loss (1,266) (3,880) Balance at December 31 47,906 56,289 Payments remaining with the National Pension Fund (119) (124) Total accrued severance plan obligations at December 31 47,787 56,165 Less current portion of accrued severance plan obligations (Note 10) 7,906 7,422 Non-current portion of accrued severance plan obligations $ 39,881 $ 48,743 Foreign Defined Benefit Pension Plans Our subsidiaries in Japan, Korea, Malaysia, the Philippines and Taiwan sponsor defined benefit plans (the “Plans”). Charges to expense are based upon actuarial analyses. The following table summarizes the changes to the Plans’ benefit obligations, fair value of the Plans’ assets and the funded status of the Plans at December 31, 2023 and 2022: For the Year Ended December 31, 2023 2022 (In thousands) Change in projected benefit obligation: Projected benefit obligation at January 1 $ 159,760 $ 200,187 Service cost 15,032 20,072 Interest cost 6,202 4,731 Benefits paid (14,056) (8,573) Actuarial (gain) loss 4,150 (24,571) Effects of curtailment (617) 508 Settlement (1,073) (16,914) Foreign exchange (gain) loss (5,117) (15,680) Projected benefit obligation at December 31 164,281 159,760 Change in plan assets: Fair value of plan assets at January 1 127,338 157,012 Actual gain (loss) on plan assets 12,325 (6,528) Employer contributions 7,368 12,946 Settlement (1,073) (16,914) Benefits paid (14,056) (8,573) Foreign exchange gain (loss) (2,706) (10,605) Fair value of plan assets at December 31 129,196 127,338 Funded status of the Plans at December 31 $ (35,085) $ (32,422) December 31, 2023 2022 (In thousands) Amounts recognized in the Consolidated Balance Sheets consist of: Prepaid benefit cost (included in non-current assets) $ 12,039 $ 12,308 Accrued benefit liability (included in pension and severance obligations) (47,124) (44,730) Net amount recognized at year end $ (35,085) $ (32,422) The accumulated benefit obligation as of December 31, 2023 and 2022 was $128.3 million and $125.6 million, respectively. The following table summarizes, by component, the change in accumulated other comprehensive income (loss), net of tax related to our Plans: Prior Service Actuarial Net Gain (Loss) Total (In thousands) Balance at December 31, 2021 $ 602 $ 5,014 $ 5,616 Amortization and settlement gain included in net periodic pension cost — (1,021) (1,021) Net gain (loss) arising during period — 9,625 9,625 Adjustments to unrealized components of defined benefit pension plan included in other comprehensive income (loss) — 8,604 8,604 Balance at December 31, 2022 $ 602 $ 13,618 $ 14,220 Amortization and settlement gain included in net periodic pension cost — (46) (46) Net gain (loss) arising during period — 1,731 1,731 Adjustments to unrealized components of defined benefit pension plan included in other comprehensive income (loss) — 1,685 1,685 Balance at December 31, 2023 $ 602 $ 15,303 $ 15,905 Information for pension plans with benefit obligations in excess of plan assets is as follows: December 31, 2023 2022 (In thousands) Plans with underfunded or non-funded projected benefit obligation: Aggregate projected benefit obligation $ 100,662 $ 96,310 Aggregate fair value of plan assets 53,539 51,581 Plans with underfunded or non-funded accumulated benefit obligation: Aggregate accumulated benefit obligation 60,638 61,764 Aggregate fair value of plan assets 21,304 20,740 The following table summarizes total pension expense: For the Year Ended December 31, 2023 2022 2021 (In thousands) Components of net periodic pension cost and total pension expense: Service cost $ 15,032 $ 20,072 $ 25,908 Interest cost 6,202 4,731 4,900 Expected return on plan assets (5,144) (5,605) (5,600) Recognized actuarial (gain) loss (156) 53 128 Net periodic pension cost 15,934 19,251 25,336 Curtailment (gain) loss (617) — (954) Settlement (gain) loss 132 (1,374) (743) Total pension expense $ 15,449 $ 17,877 $ 23,639 The components of net periodic pension cost other than the service cost component are included in other (income) expense, net The following table summarizes the weighted-average assumptions used in computing the net periodic pension cost and projected benefit obligations: For the Year Ended December 31, 2023 2022 2021 Discount rate for determining net periodic pension cost 4.2 % 2.6 % 2.3 % Discount rate for determining benefit obligations at December 31 3.8 % 4.2 % 2.6 % Rate of compensation increase for determining net periodic pension cost 3.6 % 3.7 % 3.7 % Rate of compensation increase for determining benefit obligations at December 31 3.7 % 3.6 % 3.7 % Expected rate of return on plan assets for determining net periodic 4.1 % 3.8 % 3.7 % The measurement date for determining the Plans’ assets and benefit obligations is December 31, each year. Discount rates are generally derived from yield curves constructed from high-quality corporate or foreign government bonds, for which the timing and amount of cash outflows approximate the estimated payouts. The expected rate of return assumption is based on weighted-average expected returns for each asset class. Expected returns reflect a combination of historical performance analysis and the forward-looking views of the financial markets and include input from our actuaries. We have no control over the direction of our investments in our defined benefit plans in Taiwan as the local Labor Standards Law Fund mandates such contributions into a cash account balance at the Bank of Taiwan. Our defined benefit pension plan in Malaysia is a non-funded plan, and as such, no asset exists related to this plan. Our investment strategies for our defined benefit plans in Japan, Korea and the Philippines are based on long-term, sustained asset growth through low to medium risk investments. The current rate of return assumption targets are based on asset allocation strategies as follows: Allocation Debt Equity Other Japan defined benefit plan 64 % 34 % 2 % Korea defined benefit plan 30 % 20 % 50 % Philippine defined benefit plan 56 % 42 % 2 % The fair value of our pension plan assets, by asset category utilizing the fair value hierarchy as discussed in Note 16, is as follows: December 31, 2023 December 31, 2022 Level 1 Level 2 Total Level 1 Level 2 Total (In thousands) (In thousands) Cash and cash equivalents $ 217 $ — $ 217 $ 1,117 $ — $ 1,117 Equity securities 13,680 — 13,680 13,339 — 13,339 Debt securities Government bonds 3,674 — 3,674 2,982 — 2,982 Corporate bonds 1,130 — 1,130 540 — 540 Treasury notes 11,993 — 11,993 11,561 — 11,561 Mutual and commingled funds Equity funds 29,016 7,807 36,823 23,931 7,157 31,088 Debt funds 12,031 13,163 25,194 11,651 13,409 25,060 Guaranteed investment contracts — 23,189 23,189 — 28,340 28,340 Taiwan retirement fund 12,478 — 12,478 12,845 — 12,845 Other, net — 818 818 (383) 849 466 Total fair value of pension plan assets $ 84,219 $ 44,977 $ 129,196 $ 77,583 $ 49,755 $ 127,338 The Taiwan retirement fund category of our plan assets represents accounts that our subsidiaries in Taiwan have in a government labor retirement fund in the custody of the Bank of Taiwan. The accounts earn a minimum guaranteed rate of return and are invested in a mix of cash, domestic and foreign equity securities and domestic and foreign debt securities. We expect to make contributions of approximately $11 million during 2024. We closely monitor the funded status of the Plans with respect to legislative requirements. We intend to make at least the minimum contribution required by law each year. The estimated future benefit payments related to our foreign defined benefit plans are as follows: Payments (In thousands) 2024 $ 9,369 2025 11,715 2026 12,383 2027 15,185 2028 16,062 2029 to 2033 98,940 Defined Contribution Plans We sponsor defined contribution plans in Korea, Malaysia, Taiwan and the U.S. Total defined contribution expense was $27.0 million, $24.2 million and $21.8 million for 2023, 2022 and 2021, respectively.

Dividends

Dividends	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Dividends	DividendsIn October 2020, our Board of Directors approved the initiation of a regular quarterly cash dividend on our common stock. Each quarter since the adoption of this dividend policy, the Company has declared and paid a quarterly dividend. In November 2023, our Board of Directors approved a quarterly dividend of $0.07875 per share, a 5% increase from the rate set in November 2022.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2023
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following table reflects the changes in accumulated other comprehensive income (loss), net of tax: Unrealized Gain (Losses) on Available-for-Sale Debt Investments (1) Defined Benefit Pension (2) Foreign Currency Translation Total (In thousands) Balance at December 31, 2021 $ (348) $ 5,616 $ 14,710 $ 19,978 Other comprehensive income (loss) before reclassifications (1,243) 9,625 (10,658) (2,276) Amounts reclassified from accumulated other comprehensive income (loss) 18 (1,021) — (1,003) Other comprehensive income (loss) (1,225) 8,604 (10,658) (3,279) Balance at December 31, 2022 $ (1,573) $ 14,220 $ 4,052 $ 16,699 Other comprehensive income (loss) before reclassifications 2,265 1,731 (3,819) 177 Amounts reclassified from accumulated other comprehensive income (loss) (480) (46) — (526) Other comprehensive income (loss) 1,785 1,685 (3,819) (349) Balance at December 31, 2023 $ 212 $ 15,905 $ 233 $ 16,350 (1) Amounts reclassified out of accumulated other comprehensive income (loss) are included as other (income) expense, net (Note 3). (2) 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 (Note 3).

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives We use foreign currency forward contracts to mitigate foreign currency risk of certain assets and monetary liabilities denominated in foreign currencies. We do not enter into such contracts for trading or speculative purposes. These derivative instruments are not designated as hedging instruments. As of December 31, 2023 and 2022, our foreign exchange forward contracts consisted of the following: December 31, 2023 December 31, 2022 Notional Value Fair Value (Level 2) Balance Sheet Location Notional Value Fair Value (Level 2) Balance Sheet Location (In thousands) Japanese yen $ 279,027 $ 2,745 Other current assets $ 330,179 $ 6,284 Other current assets Korean won 59,036 (97) Accrued expenses 65,927 333 Other current assets Philippine peso 6,553 (20) Accrued expenses 3,085 (6) Accrued expenses Singapore dollar 11,506 20 Other current assets — — N/A Taiwan dollar 37,914 89 Other current assets 28,763 (57) Accrued expenses Total forward contracts $ 394,036 $ 2,737 $ 427,954 $ 6,554 For the years ended December 31, 2023, 2022 and 2021, the derivatives resulted in a net loss of $38.6 million, $60.2 million and $58.8 million, respectively, which were partially offset by the foreign currency gains associated with the underlying net assets or liabilities.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
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. For our Level 2 short-term investments, we consider factors such as actual trade data, benchmark yields, broker/dealer quotes, and other similar data obtained from quoted market prices and independent pricing vendors to determine the fair value of these assets and liabilities. 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. 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. 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 our debt: December 31, 2023 December 31, 2022 Fair Carrying Fair Carrying (In thousands) Senior notes (Level 1) $ 531,778 $ 521,839 $ 523,016 $ 521,114 Revolving credit facilities and term loans (Level 2) 666,316 681,617 686,728 711,220 Total financial instruments $ 1,198,094 $ 1,203,456 $ 1,209,744 $ 1,232,334 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	12 Months Ended
	Dec. 31, 2023
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.

Business Segments, Customer Con

Business Segments, Customer Concentrations and Geographic Information	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Business Segments, Customer Concentrations and Geographic Information	Business Segments, Customer Concentrations and Geographic Information We operate as a single operating segment as managed by our Chief Executive Officer, who is considered our chief operating decision maker (“CODM”). The CODM bears the ultimate responsibility for, and is actively engaged in, the allocation of resources and the evaluation of our operating and financial results. We have concluded that we have a single operating segment based on the following: • We are managed under a functionally-based organizational structure with the head of each function reporting directly to the CODM; • We assess performance, including incentive compensation, based on consolidated operating performance and financial results; • Our CODM allocates resources and makes other operating decisions based on specific customer business opportunities and • We have an integrated process for the design, development and manufacturing services we provide to all of our customers. We also have centralized sales and administrative functions. Net sales by product group consist of the following: For the Year Ended December 31, 2023 2022 2021 (In thousands) Advanced Products $ 5,032,859 $ 5,367,589 $ 4,409,207 Mainstream Products 1,470,206 1,723,996 1,729,122 Total net sales $ 6,503,065 $ 7,091,585 $ 6,138,329 (1) Advanced Products include flip chip, memory and wafer-level processing and related test services. (2) Mainstream Products include all other wirebond packaging and related test services. Net sales by end market consist of the following : For the Year Ended December 31, 2023 2022 2021 Communications (smartphones, tablets) 50 % 44 % 41 % Automotive, industrial and other (ADAS, electrification, infotainment, safety) 21 % 20 % 21 % Computing (data center, infrastructure, PC/laptop, storage) 16 % 16 % 16 % Consumer (AR & gaming, connected home, home electronics, wearables) 13 % 20 % 22 % Total net sales 100 % 100 % 100 % Net sales by region based on customer headquarters location consist of the following: For the Year Ended December 31, 2023 2022 2021 (In thousands) Europe, Middle East and Africa $ 1,043,880 $ 1,084,853 $ 1,061,369 Japan 935,620 1,132,121 1,253,717 Asia Pacific (excluding Japan) 704,520 1,017,246 999,591 Total foreign countries 2,684,020 3,234,220 3,314,677 United States 3,819,045 3,857,365 2,823,652 Total net sales $ 6,503,065 $ 7,091,585 $ 6,138,329 In 2023, 2022 and 2021 one customer accounted for 27.7%, 20.6% and 13.7% of total net sales, respectively. In 2022, a second customer accounted for 10.1% of total net sales. Property, plant and equipment, net, based on physical location, consist of the following: December 31, 2023 2022 (In thousands) China $ 385,544 $ 476,945 Japan 143,399 121,842 Korea 1,781,632 1,868,956 Malaysia 51,164 41,978 Philippines 183,430 195,805 Portugal 108,982 82,454 Taiwan 272,428 261,449 Vietnam 365,059 79,630 Other foreign countries 272 583 Total foreign countries 3,291,910 3,129,642 United States 7,535 5,972 Total property, plant and equipment, net $ 3,299,445 $ 3,135,614

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS Balance at Additions (Credited) Charged to Expense Write-offs Balance at (In thousands) Deferred tax asset valuation allowance: Year ended at December 31, 2021 $ 121,310 3,653 (2,606) $ 122,357 Year ended at December 31, 2022 $ 122,357 (17,762) (2,726) $ 101,869 Year ended at December 31, 2023 $ 101,869 15,838 (2,896) $ 114,811

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss) Attributable to Parent	$ 359,813	$ 765,823	$ 642,995

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	12 Months Ended
	Dec. 31, 2023 shares	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Giel Rutten [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On November 8, 2023, Giel Rutten, Amkor’s President and Chief Executive Officer, adopted a “Rule 10b5-1 trading arrangement” as such term is defined in paragraph (a) of Item 408 of Regulation S-K promulgated under the Securities Act, which is intended to satisfy the affirmative defense of Rule 10b5-1(c). Mr. Rutten’s Rule 10b5-1 trading arrangement will terminate on the earliest of: (a) August 30, 2024; (b) the first date on which all trades have been executed or all trading orders relating to such trades have expired; and (c) the date on which Mr. Rutten gives notice to terminate his Rule 10b5-1 trading arrangement. 175,000 shares of our common stock are to be sold under Mr. Rutten’s Rule 10b5-1 trading arrangement.
Name	Giel Rutten
Title	President and Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	November 8, 2023
Arrangement Duration	296 days
Aggregate Available	175,000	175,000

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description Of Business	Description of Business Amkor is one of the world’s leading providers of outsourced semiconductor packaging and test services. Amkor was a pioneer in the outsourcing of semiconductor packaging and test services, and over the years we have built a leading position by: • Designing and developing innovative packaging and test technologies focused on advanced packaging solutions in high growth markets, including artificial intelligence; • Building expertise in high-volume manufacturing processes and developing a reputation for high quality and solid execution; • Cultivating long-standing relationships with our customers, which include many of the world’s leading semiconductor companies; • Collaborating with customers, foundries, OEMs and equipment and material suppliers; • Focusing on strategic end markets that offer solid growth potential; • Providing a geographically diverse operating base with manufacturing facilities in multiple countries across Asia and in Europe; and • Developing a competitive cost structure through disciplined capital investment.
Basis of Presentation	Basis of Presentation Our Consolidated Financial Statements include the accounts of Amkor Technology, Inc. and its subsidiaries. Our Consolidated Financial Statements reflect the elimination of all significant inter-company accounts and transactions. Our investments in variable interest entities in which we are the primary beneficiary are consolidated. We reflect the remaining portion of variable interest entities and foreign subsidiaries that are not wholly owned as noncontrolling interests.
Use of Estimates	The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, income taxes, inventory and long-lived assets. These estimates are based on management’s best knowledge of current events, historical experience, actions that we may undertake in the future and on various other assumptions that are believed to be reasonable under the circumstances. As a result, actual results could differ materially from these estimates and assumptions, including the impact of any deterioration in the global business and economic environment. Certain prior year amounts have been reclassified to conform to current year presentation.
Consolidation of Variable Interest Entities	Consolidation of Variable Interest Entities We have variable interests in certain Philippine realty corporations in which we have a 40% ownership. We lease land and buildings in the Philippines from these entities and we are the primary beneficiary of these arrangements. As of December 31, 2023, the combined book value of the assets and liabilities associated with these Philippine realty corporations included in our Consolidated Balance Sheet was $17.3 million and $0.1 million, respectively. The impact of consolidating these variable interest entities on our Consolidated Statements of Income was not significant, and other than our lease payments, we have not provided any significant assistance or other financial support to these variable interest entities for the years ended December 31, 2023, 2022 or 2021. The creditors of the Philippine realty corporations have no recourse to our general credit.
Foreign Currency Translation	Foreign Currency Translation The U.S. dollar is the functional currency of our subsidiaries other than our Japan operations. The foreign currency asset and liability amounts at these subsidiaries are remeasured into U.S. dollars at end-of-period exchange rates, except for nonmonetary items which are remeasured at historical rates. Foreign currency income and expenses are remeasured at daily exchange rates, except for expenses related to balance sheet amounts which are remeasured at historical exchange rates. Exchange gains and losses arising from remeasurement of foreign currency-denominated monetary assets and liabilities are included in other (income) expense, net in the period in which they occur. The Japanese yen is the functional currency of our Japan operations. The asset and liability amounts of our Japan operations are translated into U.S. dollars at end-of-period exchange rates. Income and expenses are translated into U.S. dollars at the daily exchange rate. The resulting translation adjustments are reported as a component of accumulated other comprehensive income in the stockholders’ equity section of the balance sheet. Assets and liabilities denominated in a currency other than the functional currency are remeasured into the functional currency prior to translation into U.S. dollars, and the resulting transaction exchange gains or losses are included in other (income) expense, net in the period in which they occur.
Risks and Concentrations	Risks and Concentrations The semiconductor industry is characterized by rapid technological change, competitive pricing pressures and cyclical market patterns. Our financial results are affected by a wide variety of factors, including general economic conditions worldwide, economic conditions specific to the semiconductor industry, the timely implementation of new package and test technologies, the ability to safeguard patents and intellectual property in a rapidly evolving market and reliance on materials and equipment suppliers. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns at various times. Our profitability and ability to generate cash from operations is principally dependent upon demand for semiconductors, the utilization of our capacity, semiconductor package mix, the average selling price of our services, our ability to manage our capital expenditures and our ability to control our costs including labor, material, overhead and financing costs. A significant portion of our revenues is concentrated with a small group of customers (Note 18). Direct sales to our largest customer accounted for 27.7% of our net sales for the year ended December 31, 2023. The loss of a significant customer, a business combination among customers, a reduction in orders or decrease in price from a significant customer or disruption in any of our significant strategic partnerships or other commercial arrangements could have a material adverse effect on our business, liquidity, results of operations, financial condition and cash flows. Financial instruments, for which we are subject to credit risk, consist principally of accounts receivable and cash, cash equivalents and short-term investments. With respect to accounts receivable, we mitigate our credit risk by selling primarily to well-established companies, performing ongoing credit evaluations and making frequent contact with customers. In addition, we may utilize non-recourse factoring to mitigate credit risk when considered appropriate. We have historically mitigated our credit risk with respect to cash and cash equivalents through diversification of our holdings into various high quality money market funds and bank deposit accounts. Our short-term investments are principally investments in debt securities with maximum duration of twenty-four months and range from AAA to BBB-rated financial instruments. Our short-term investments are primarily in corporate bonds, direct obligations of the U.S. Government or its agencies, asset-backed securities and commercial paper. At December 31, 2023, our cash and cash equivalents were primarily maintained in various U.S. and foreign bank operating and time deposit accounts and invested in various available-for-sale debt investments. See Note 6 for further discussion regarding our available-for-sale debt investments.
Contingencies and Litigation	Contingencies and Litigation We may be subject to certain legal proceedings, lawsuits and other claims, as discussed in Note 17. We accrue for a loss contingency, including legal proceedings, lawsuits, pending claims and other legal matters, when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, we accrue for the amount at the low end of the range. 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.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Our cash and cash equivalents are primarily maintained in various U.S. and foreign bank operating and time deposit accounts and invested in various available-for-sale debt investments. See Note 6 for further discussion regarding our available-for-sale debt investments.
Restricted Cash	Restricted Cash Restricted cash, non-current, mainly consists of collateral to fulfill utility requirements.
Investments	Investments Generally, we classify our short-term investments in fixed income securities as available-for-sale debt investments. All of our available-for-sale debt investments as of December 31, 2023 are available to fund current operations and are recorded at fair value (Note 6). 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. 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 in determining if and when a decline in value below the adjusted cost of our available-for-sale debt investments is an impairment. 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 impairment is considered based on condition (iii), the amount representing credit losses will be recognized in earnings and as an allowance for credit losses. The amount relating to all other factors will be recognized in other comprehensive income.
Inventories	Inventories Inventories consist of raw materials and purchased components and are stated at the lower of cost and net realizable value. Cost is principally determined by standard cost or the weighted moving average method, both of which approximate actual cost. We review and set our standard costs as needed, but at a minimum on a quarterly basis. We reduce the carrying value of our inventories for the cost of inventory we estimate is excess and obsolete based on the age of our inventories. When a determination is made that the inventory will not be utilized in production or is not saleable, it is written-off.
Other Current Assets	Other Current Assets Other current assets consist principally of prepaid assets.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost. Depreciation is calculated by the straight-line method over the estimated useful lives of depreciable assets which are as follows: Buildings and improvements 10 to 40 years Machinery and equipment 2 to 7 years Software and computer equipment 3 to 5 years Furniture, fixtures and other equipment 4 to 10 years Cost and accumulated depreciation for property retired or disposed of are removed from the accounts, and any resulting gain or loss is included in earnings. Expenditures for maintenance and repairs are charged to expense as incurred. We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Recoverability of a long-lived asset group to be held and used in operations is measured by a comparison of the carrying amount to the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset group. If such asset group is considered to be impaired, the impairment loss is measured as the amount by which the carrying amount of the asset group exceeds its fair value. Long-lived assets to be disposed of are carried at the lower of cost or fair value less the costs of disposal.
Leases	Leases We lease certain machinery and equipment, office space, and manufacturing facilities. Leases with an initial term of 12 months or less are not recorded on the balance sheet, and we recognize lease expense for these leases on a straight-line basis over the lease term. We combine lease components (e.g., fixed payments including rent, real estate taxes and insurance costs) with the non-lease components (e.g., common-area maintenance costs) for all asset classes. We use our incremental borrowing rate based on the information available at the lease commencement date to determine the lease liability. Our leases have remaining lease terms ranging from less than one year to 82 years. For purposes of calculating our lease liabilities, our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise those options. Certain leases also include options to purchase the leased property. Total long-term finance lease liabilities
Goodwill	Goodwill Goodwill is recorded when the cost of an acquisition exceeds the fair value of the net tangible and identifiable intangible assets acquired. We review goodwill for impairment annually during the fourth quarter of each year and whenever events or changes in circumstances indicate that an impairment may exist. Impairment losses are recorded when the carrying amount of the reporting unit exceeds its fair value. The balance of goodwill in our Consolidated Balance Sheets reflects adjustments for foreign currency translation.
Other Assets	Other Assets Other assets consist principally of deferred tax assets, refundable security deposits and advanced payments to vendors.
Derivatives	Derivatives We use foreign exchange forward contracts, generally settled monthly, to manage a portion of our exposure to foreign exchange risk. The derivatives are recorded at the fair value either in other current assets or accrued expenses, with the associated gains and losses charged to other (income) expense, net
Fair Value Measurements	Fair Value Measurements
Revenue Recognition	Revenue Recognition We recognize revenue, net of sales, use, value-added and other similar taxes, as a performance obligation is satisfied in an amount reflecting the consideration to which we expect to be entitled. We apply a five-step approach in determining the amount and timing of revenue to be recognized: (1) identifying the contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when the performance obligation is satisfied. Substantially all of our revenue is recognized as services are rendered. Our packaging and test services are our performance obligations to our customers. Our packaging services include wafer bump, probe and assembly. We provide packaging and test services to our customers either individually or as part of a combined offering. In a combined offering, we account for the individual services separately if they are determined to be distinct. We determine a service to be distinct if it is separately identifiable from other services in the combined offering and if a customer can benefit from the unique service on its own or with other resources that are readily available to the customer. The consideration, including variable consideration, is allocated between the distinct services in a combined offering based upon the stand-alone selling prices of the individual services. Our services involve a high degree of specialization which are unique based on the design and purpose of the customer’s wafers. Accordingly, our negotiated pricing reflects the customized nature of our services and represents a customer-specific stand-alone selling price. We recognize revenue as services are rendered, which generally occurs over the course of two to three weeks. Services are generally billed at completion of each individual packaging or test service or in some instances at the completion of all services in a combined offering. We recognize revenue over time as services are rendered because our services create or enhance the customer’s wafer. We utilize an input method (cost incurred plus estimated margin) to determine the amount of revenue to recognize for in-process, but incomplete, customer orders at a reporting date. During the period of providing our services, we generally do not control or take ownership of customers’ wafers, nor do we include the cost of the wafer in our cost calculations. We believe that a cost-based input method is the most appropriate manner to measure how we satisfy our performance obligations to customers because the effort and costs incurred to package and/or test customer wafers are not linear over the duration of these services. Shipping and handling costs are accounted for as a cost to fulfill our performance obligations to customers. Accordingly, we record customer payments of shipping and handling costs as a component of net sales, and the costs incurred for shipping and handling are then charged to cost of sales. Unbilled receivables are revenues that have been recognized for performance obligations that have been satisfied, or partially satisfied, in advance of billing the customer. Revenue may be recognized in advance of billing as our contracts provide us with an unconditional right to consideration for work that is performed. Total unbilled receivables as of December 31, 2023 and 2022 were $260.8 million and $301.7 million, respectively. These amounts are included in accounts receivable, net of allowances in our Consolidated Balance Sheets. At times, the company receives cash payments from customers in advance of the company’s performance. In such cases, we record deferred revenue until the performance obligation is satisfied, which represents a contract liability and is included in accrued expenses and other non-current liabilities in the consolidated balance sheets. These contract liabilities are classified as either current or long-term based on the timing of when the company expects to recognize revenue. Contract liabilities were $135.5 million and $170.6 million as of December 31, 2023 and December 31, 2022, respectively. As of December 31, 2023 and December 31, 2022, the short-term portion of the liability was $71.1 million and $81.5 million, respectively. The remainder of the December 31, 2023 contract liability balance is expected to be recognized in revenue over the next 1-5 years. Revenue recognized during the year that was included in the contract liability balance at the beginning of the period was $66.9 million, $101.2 million, and $29.0 million, for 2023, 2022 and 2021, respectively.
Research and Development Costs	Research and Development Costs Research and development expenses include costs attributable to the conduct of research and development programs primarily related to the development of new package designs or technologies and improving the efficiency and capabilities of our existing production processes. Such costs include labor, materials, supplies, depreciation and maintenance of research equipment, services provided by outside contractors and the allocable portions of facility costs such as rent, utilities, insurance, repairs and maintenance, depreciation and general support services. Costs associated with research and development are expensed as incurred.
Income Taxes	Income Taxes Income taxes are accounted for using the asset and liability method. Under this method, deferred income tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis as well as for net operating loss and tax credit carryforwards. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is provided for those deferred tax assets for which it is more likely than not that the related tax benefits will not be realized. 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 recent results of operations. With the exception of a certain foreign jurisdiction and select U.S. and foreign carryforwards, we consider it more likely than not that we will have sufficient taxable income to allow us to realize these deferred tax assets. However, in the event taxable income falls short of current expectations, we may need to establish a valuation allowance against such deferred tax assets.
Recently Issued Standards	Recently Issued Standards In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires disclosure of additional income tax information, primarily related to effective tax rate reconciliation and income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. Adoption of this ASU should be applied on a prospective basis, but retrospective application is permitted. We are currently evaluating the impact of this new standard on our financial statements, which is expected to result in enhanced disclosures.

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of property, plant and equipment	Depreciation is calculated by the straight-line method over the estimated useful lives of depreciable assets which are as follows: Buildings and improvements 10 to 40 years Machinery and equipment 2 to 7 years Software and computer equipment 3 to 5 years Furniture, fixtures and other equipment 4 to 10 years Property, plant and equipment consist of the following: December 31, 2023 2022 (In thousands) Land $ 212,722 $ 214,763 Buildings and improvements 2,080,589 1,817,135 Machinery and equipment 7,022,614 6,757,652 Finance lease assets 209,506 165,122 Furniture, fixtures and other equipment 22,655 23,240 Software and computer equipment 200,362 240,610 Construction in progress 223,332 152,809 Total property, plant and equipment 9,971,780 9,371,331 Accumulated depreciation and amortization (6,672,335) (6,235,717) Total property, plant and equipment, net $ 3,299,445 $ 3,135,614 The following table summarizes our depreciation expense: For the Year Ended December 31, 2023 2022 2021 (In thousands) Depreciation expense $ 630,941 $ 612,105 $ 562,962

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of all common stock option activity	The following table summarizes our stock option activity for the year ended December 31, 2023: Number of Weighted-Average Weighted-Average Aggregate Outstanding at December 31, 2022 2,376 $ 10.54 Granted — — Exercised (345) 10.31 Forfeited or expired — — Outstanding at December 31, 2023 2,031 $ 10.58 4.98 years $ 46,068 Fully vested at December 31, 2023 and expected to vest thereafter 2,029 $ 10.58 4.98 years $ 46,029 Exercisable at December 31, 2023 1,973 $ 10.51 4.93 years $ 44,903
Schedule of restricted share activity	The following table summarizes our restricted share activity for the year ended December 31, 2023: Number of Weighted- average Non-vested at December 31, 2022 109 $ 15.38 Awards granted — — Awards vested (109) 15.38 Awards forfeited — — Non-vested at December 31, 2023 — $ — The following table summarizes our RSU and PSU activity: Number of Weighted- average Non-vested at December 31, 2020 — $ — Awards granted 295 22.48 Awards vested — — Awards forfeited (9) 22.58 Non-vested at December 31, 2021 286 22.48 Awards granted 531 22.29 Awards vested (22) 22.23 Awards forfeited (57) 22.63 Non-vested at December 31, 2022 738 22.34 Awards granted 1,049 26.72 Awards vested (464) 22.19 Awards forfeited (16) 25.24 Non-vested at December 31, 2023 1,307 $ 25.87

Other Income and Expense (Table

Other Income and Expense (Tables)	12 Months Ended
	Dec. 31, 2023
Other Income and Expenses [Abstract]
Schedule of other (income) expense	Other income and expense consists of the following: For the Year Ended December 31, 2023 2022 2021 (In thousands) Interest income $ (48,458) $ (12,762) $ (1,065) Foreign currency (gain) loss, net 18,361 (1,572) 723 Loss on debt retirement — 464 — Other (2,457) (4,439) (2,799) Total other (income) expense, net $ (32,554) $ (18,309) $ (3,141)

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of income (loss) before income tax, domestic and foreign	Geographic sources of income (loss) before taxes are as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) United States $ 94,643 $ 81,488 $ 81,994 Foreign 349,198 775,444 633,072 Income before taxes $ 443,841 $ 856,932 $ 715,066
Schedule of components of income tax provision (benefit)	The components of the provision (benefit) for income taxes are as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Current: Federal $ 19,831 $ 40,063 $ 9,649 State 7 150 198 Foreign 48,478 61,300 48,936 68,316 101,513 58,783 Deferred: Federal 8,899 (10,156) 20,478 State 1 1,458 361 Foreign 4,494 (2,925) (10,163) 13,394 (11,623) 10,676 Income tax expense $ 81,710 $ 89,890 $ 69,459
Schedule of effective income tax rate reconciliation	The reconciliation between the U.S. federal statutory income tax rate of 21% and our effective tax rate is as follows: For the Year Ended December 31, 2023 2022 2021 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % Foreign income taxed at different rates (4.2) (12.0) (9.5) Foreign exchange (loss) gain 0.5 2.2 (2.3) Change in valuation allowance 2.9 (2.4) 0.1 Income tax credits generated (7.5) (6.1) (5.1) Foreign earnings and profits 7.0 9.0 5.7 Foreign derived intangible income (1.6) (0.9) (1.1) Settlements and changes in uncertain tax positions (0.5) (0.2) 0.8 Other 0.8 (0.1) 0.1 Income tax expense 18.4 % 10.5 % 9.7 %
Schedule of deferred tax assets and liabilities	The following is a summary of the components of our deferred tax assets and liabilities: December 31, 2023 2022 (In thousands) Deferred tax assets: Net operating loss carryforwards $ 33,679 $ 49,846 Tax credit carryforwards 88,147 92,368 Property, plant and equipment 21,387 15,328 Deferred interest expense 476 — Accrued liabilities 37,832 39,929 Receivable 30,086 29,178 Unrealized foreign exchange loss 7,205 8,018 Revenue recognition — 1,564 Operating lease liabilities 16,053 26,955 Other 15,219 14,665 Total deferred tax assets 250,084 277,851 Valuation allowance (114,811) (101,869) Total deferred tax assets net of valuation allowance 135,273 175,982 Deferred tax liabilities: Property, plant and equipment 34,206 50,215 Deferred gain 5,739 7,839 Unrealized foreign exchange gain 3,129 5,242 Unbilled receivables 8,995 822 Operating lease right of use assets 16,031 26,241 Other 5,533 7,433 Total deferred tax liabilities 73,633 97,792 Net deferred tax assets $ 61,640 $ 78,190 Recognized as: Other assets $ 73,585 $ 86,616 Other non-current liabilities (11,945) (8,426) Total $ 61,640 $ 78,190
Schedule of valuation allowance	Valuation allowance against deferred tax assets consist of the following: December 31, 2023 2022 (In thousands) Valuation allowance: U.S. $ 44,426 $ 40,610 Foreign 70,385 61,259 Total valuation allowance $ 114,811 $ 101,869
Schedule of operating loss carryforwards	Our net operating loss carryforwards are as follows: December 31, 2023 2022 Expiration (In thousands) U.S. federal net operating loss carryforwards $ 5,611 $ 13,003 2024 U.S. state net operating loss carryforwards 32,612 38,384 2024-2036 Foreign net operating loss carryforwards 196,636 240,740 2027-2031
Schedule of tax credit carryforwards	Our tax credit carryforwards are as follows: December 31, 2023 2022 Expiration (In thousands) U.S. Foreign Tax Credits $ 51,512 $ 54,130 2027-2033 U.S. Other Tax Credits 2,559 110 2026-2033 Foreign Tax Credits 34,546 38,128 2024-2033
Schedule of unrecognized tax benefits rollforward	A reconciliation of the beginning and ending gross amount of unrecognized tax benefits is as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Balance at January 1 $ 33,253 $ 37,293 $ 32,598 Additions based on tax positions related to the current year — 1,519 9,562 Additions for tax positions of prior years 495 1,909 1,740 Reductions for tax positions of prior years (345) (5,755) (66) Reductions related to settlements with tax authorities — (988) (1,266) Reductions from lapse of statutes of limitations (1,866) (725) (5,275) Balance at December 31 $ 31,537 $ 33,253 $ 37,293

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Computation of basic and diluted earnings per share	The following table summarizes the computations of basic and diluted EPS: For the Year Ended December 31, 2023 2022 2021 (In thousands, except per share data) Net income attributable to Amkor common stockholders $ 359,813 $ 765,823 $ 642,995 Weighted-average number of common shares outstanding — basic 245,628 244,676 243,878 Effect of dilutive securities: Share-based awards 1,548 1,529 1,826 Weighted-average number of common shares outstanding — diluted 247,176 246,205 245,704 Net income attributable to Amkor per common share: Basic $ 1.46 $ 3.13 $ 2.64 Diluted $ 1.46 $ 3.11 $ 2.62
Schedule of Antidilutive effect of potential shares of common stock that were 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 Year Ended December 31, 2023 2022 2021 (In thousands) Share-based awards 2 180 112

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of debt securities available-for-sale	The following table summarizes our cash equivalents and available-for-sale debt investments: December 31, 2023 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Asset-backed securities $ 138 $ — $ — $ 138 $ — $ 138 Commercial paper 48,063 — — 48,063 — 48,063 Money market funds 60,719 — — 60,719 60,719 — U.S. government bonds 2,996 — — 2,996 2,996 — Total cash equivalents (2) 111,916 — — 111,916 63,715 48,201 Short-term investments Asset-backed securities 65,340 170 (22) 65,488 — 65,488 Certificate of deposits 17,086 — — 17,086 17,086 — Commercial paper 56,273 — — 56,273 — 56,273 Corporate bonds 251,671 432 (299) 251,804 — 251,804 U.S. government agency bonds 13,200 — (9) 13,191 — 13,191 U.S. government bonds 65,881 13 (79) 65,815 65,815 — Total short-term investments 469,451 615 (409) 469,657 82,901 386,756 Total $ 581,367 $ 615 $ (409) $ 581,573 $ 146,616 $ 434,957 December 31, 2022 Fair Value Level Amortized Cost Gross Unrealized Gains Gross Unrealized Losses (1) Total Fair Value Level 1 Level 2 (In thousands) Cash equivalents Asset-backed securities $ 25 $ — $ — $ 25 $ — $ 25 Commercial paper 69,101 — — 69,101 — 69,101 Money market funds 97,650 — — 97,650 97,650 — Municipal bonds 1,001 — — 1,001 — 1,001 US government bonds 10,767 1 — 10,768 10,768 — US government agency bonds 16,982 3 — 16,985 — 16,985 Total cash equivalents (2) 195,526 4 — 195,530 108,418 87,112 Short-term investments Asset-backed securities 25,677 7 (134) 25,550 — 25,550 Certificate of deposits 17,362 — — 17,362 17,362 — Commercial paper 27,866 — — 27,866 — 27,866 Corporate bonds 198,868 7 (1,529) 197,346 — 197,346 Foreign government bonds 996 — (4) 992 — 992 Mortgage-backed securities 696 — (2) 694 — 694 Municipal bonds 364 — (2) 362 — 362 U.S. government agency bonds 735 — (1) 734 — 734 U.S. government bonds 6,704 1 (20) 6,685 6,685 — Total short-term investments 279,268 15 (1,692) 277,591 24,047 253,544 Total $ 474,794 $ 19 $ (1,692) $ 473,121 $ 132,465 $ 340,656 (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 we do not believe it is more likely than not that we will be required to sell these investments before recovery of their amortized cost bases. (2) During the years ended December 31, 2023, 2022, and 2021 we sold cash equivalent investments for proceeds of $47.0 million, $29.6 million and $12.8 million, respectively, and realized no gain or loss on such sales. The following table summarizes the contractual maturities of our cash equivalents and available-for-sale debt investments as of December 31, 2023: Amortized Cost Fair Value Within 1 year $ 406,551 $ 406,346 After 1 year through 5 years 109,338 109,601 Asset-backed securities 65,478 65,626 Total $ 581,367 $ 581,573

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of property, plant and equipment	Depreciation is calculated by the straight-line method over the estimated useful lives of depreciable assets which are as follows: Buildings and improvements 10 to 40 years Machinery and equipment 2 to 7 years Software and computer equipment 3 to 5 years Furniture, fixtures and other equipment 4 to 10 years Property, plant and equipment consist of the following: December 31, 2023 2022 (In thousands) Land $ 212,722 $ 214,763 Buildings and improvements 2,080,589 1,817,135 Machinery and equipment 7,022,614 6,757,652 Finance lease assets 209,506 165,122 Furniture, fixtures and other equipment 22,655 23,240 Software and computer equipment 200,362 240,610 Construction in progress 223,332 152,809 Total property, plant and equipment 9,971,780 9,371,331 Accumulated depreciation and amortization (6,672,335) (6,235,717) Total property, plant and equipment, net $ 3,299,445 $ 3,135,614 The following table summarizes our depreciation expense: For the Year Ended December 31, 2023 2022 2021 (In thousands) Depreciation expense $ 630,941 $ 612,105 $ 562,962

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of components of lease expense	The components of lease expense were as follows: For the Year Ended December 31, 2023 2022 2021 (In thousands) Operating lease cost $ 70,722 $ 81,410 $ 64,902 Finance lease cost Amortization of leased assets 42,345 24,644 14,196 Interest on lease liabilities 5,521 3,891 2,768 Total finance lease cost 47,866 28,535 16,964 Short-term lease cost 4,788 5,749 6,264 Variable lease cost 6,921 6,592 7,409 Net lease cost $ 130,297 $ 122,286 $ 95,539 Other information related to leases was as follows: For the Year Ended December 31, 2023 2022 2021 Supplemental Cash Flows Information (in thousands) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 73,774 $ 81,044 $ 64,786 Operating cash flows for finance leases 5,419 3,933 1,745 Financing cash flows for finance leases 66,398 40,673 20,373 Weighted Average Remaining Lease Term (years) Operating leases 6.1 4.2 3.2 Finance leases 3.2 2.3 3.1 Weighted Average Discount Rate Operating leases 5.2 % 4.4 % 3.6 % Finance leases 5.7 % 4.1 % 3.2 %
Schedule of maturity of operating lease liabilities	Maturities of lease liabilities were as follows: December 31, 2023 Operating Leases Finance Leases (In thousands) 2024 $ 36,916 $ 62,306 2025 19,869 25,259 2026 12,752 11,436 2027 9,144 3,568 2028 6,017 2,511 Thereafter 20,488 12,913 Total future minimum lease payments 105,186 117,993 Less: Imputed interest (14,733) (12,438) Total $ 90,453 $ 105,555
Schedule of maturity of finance lease liabilities	Maturities of lease liabilities were as follows: December 31, 2023 Operating Leases Finance Leases (In thousands) 2024 $ 36,916 $ 62,306 2025 19,869 25,259 2026 12,752 11,436 2027 9,144 3,568 2028 6,017 2,511 Thereafter 20,488 12,913 Total future minimum lease payments 105,186 117,993 Less: Imputed interest (14,733) (12,438) Total $ 90,453 $ 105,555

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of accrued expenses	Accrued expenses consist of the following: December 31, 2023 2022 (In thousands) Payroll and benefits $ 115,604 $ 137,445 Deferred revenue and customer advances 71,117 81,459 Short-term finance lease liability 57,761 56,570 Income taxes payable 35,215 50,685 Accrued interest 11,175 10,878 Accrued severance plan obligations (Note 12) 7,906 7,422 Other accrued expenses 59,636 57,382 Total accrued expenses $ 358,414 $ 401,841

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of short term borrowings and long term debt	Short-term borrowings and long-term debt consist of the following: December 31, 2023 2022 (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.: Term loan, fixed rate at 1.85%, due April 2024 (1) — — Term loan, fixed rate at 2.12%, due December 2028 200,000 200,000 Amkor Technology Japan, Inc.: Short-term term loans, variable rate (2) 5,098 4,042 Term loan, fixed rate at 1.30%, due July 2023 — 29,744 Term loan, fixed rate at 1.35%, due December 2024 40,414 86,943 Term loan, fixed rate at 1.20%, due December 2025 30,913 49,878 Term loan, fixed rate at 1.23%, due December 2026 55,729 79,927 Term loan, fixed rate at 1.59%, due December 2027 89,053 119,738 Term loan, fixed rate at 1.80%, due December 2028 (3) 124,078 — Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loans, SOFR plus 0.75%, due March 2024 (4) — 46,000 Term loans, SOFR plus 0.75%, due June 2025 (4) 37,000 39,000 Term loans, SOFR plus 0.75%, due 2025 (4) 57,500 59,500 Term loans, SOFR plus 1.40%, due December 2026 (5) 45,000 — Other: Credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) (6) — — Senior secured revolving credit facility, applicable bank rate plus 1.75%, due March 2027 (Singapore) (7) — — 1,209,785 1,239,772 Less: Unamortized discount and deferred debt costs, net (6,329) (7,438) Less: Short-term borrowings and current portion of long-term debt (131,624) (143,813) Long-term debt $ 1,071,832 $ 1,088,521 (1) In April 2021, we entered into a ₩80 billion term loan agreement with the option to borrow and re-borrow the funds up to six times per year through April 2024. Principal is payable at maturity, and interest is payable monthly. As of December 31, 2023, ₩80.0 billion, or approximately $62 million, was available to be drawn. (2) We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. As of December 31, 2023, $7.7 million was available to be drawn. (3) In December 2023, we borrowed ¥17.5 billion (US$123.3 million) under a new term loan agreement due December 2028, guaranteed by Amkor Technology, Inc. and our subsidiary, ATSH. Principal is due in 20 equal, quarterly installments plus accrued interest, through maturity. (4) In June 2023, Amkor Assembly & Test (Shanghai) Co. Ltd. amended all term loans to replace London Interbank Offered Rate (“LIBOR”) with a Secured Overnight Financing Rate (“SOFR”) plus 0.75% annual base rate. This contractual amendment is treated as a modification with no recognized gain or loss. (5) In December 2023, we entered into a $45.0 million term loan. Principal is payable in semiannual installments of $0.5 million, with the remaining balance due at maturity. Interest is payable quarterly. (6) In March 2022, ATT amended an existing revolving credit facility to reduce the availability from $36.0 million to $15.0 million. As of December 31, 2023, $15.0 million was available for future borrowings under such credit facility. (7) In March 2022, ATSH entered into the 2022 Singapore Revolver, which is guaranteed by Amkor Technology, Inc., ATT and AATT. The maximum borrowing capacity under the 2022 Singapore Revolver is limited to a base amount equal to the lesser of: (1) $600.0 million; or (2) $250.0 million plus a variable amount equal to 37.5% of our consolidated accounts receivable balance. As of December 31, 2023, $600.0 million was available for future borrowings under the 2022 Singapore Revolver.
Schedule of interest rates	Refer to the table above for the interest rates on our fixed-rate debt and to the table below for the interest rates on our variable-rate debt. December 31, 2023 2022 Amkor Technology Japan, Inc: Short-term term loans, variable rate 0.24 % 0.29 % Amkor Assembly & Test (Shanghai) Co., Ltd.: Term loans, SOFR plus 0.75% due March 2024 — 5.83 % Term loans, SOFR plus 0.75% due June 2025 6.07 % 5.55 % Term loans, SOFR plus 0.75%, due 2025 6.07 % 5.48 % Term loans, SOFR plus 1.40%, due December 2026 6.76 % —
Schedule of maturities of long-term debt	Maturities Total Debt (In thousands) Payments due for the year ending December 31, 2024 $ 131,624 2025 222,612 2026 158,655 2027 622,079 2028 74,815 Thereafter — Total debt $ 1,209,785

Pension and Severance Plans (Ta

Pension and Severance Plans (Tables)	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Schedule of accrued severance obligation	The changes to the balance of our accrued severance plan obligations are as follows: For the Year Ended December 31, 2023 2022 (In thousands) Balance at January 1 $ 56,289 $ 73,345 Provision of severance benefits 1,653 2,119 Severance payments (8,770) (15,295) Foreign currency (gain) loss (1,266) (3,880) Balance at December 31 47,906 56,289 Payments remaining with the National Pension Fund (119) (124) Total accrued severance plan obligations at December 31 47,787 56,165 Less current portion of accrued severance plan obligations (Note 10) 7,906 7,422 Non-current portion of accrued severance plan obligations $ 39,881 $ 48,743
Schedule of changes in projected benefit obligations and fair value of plan assets	The following table summarizes the changes to the Plans’ benefit obligations, fair value of the Plans’ assets and the funded status of the Plans at December 31, 2023 and 2022: For the Year Ended December 31, 2023 2022 (In thousands) Change in projected benefit obligation: Projected benefit obligation at January 1 $ 159,760 $ 200,187 Service cost 15,032 20,072 Interest cost 6,202 4,731 Benefits paid (14,056) (8,573) Actuarial (gain) loss 4,150 (24,571) Effects of curtailment (617) 508 Settlement (1,073) (16,914) Foreign exchange (gain) loss (5,117) (15,680) Projected benefit obligation at December 31 164,281 159,760 Change in plan assets: Fair value of plan assets at January 1 127,338 157,012 Actual gain (loss) on plan assets 12,325 (6,528) Employer contributions 7,368 12,946 Settlement (1,073) (16,914) Benefits paid (14,056) (8,573) Foreign exchange gain (loss) (2,706) (10,605) Fair value of plan assets at December 31 129,196 127,338 Funded status of the Plans at December 31 $ (35,085) $ (32,422)
Schedule of amounts recognized in balance sheet	December 31, 2023 2022 (In thousands) Amounts recognized in the Consolidated Balance Sheets consist of: Prepaid benefit cost (included in non-current assets) $ 12,039 $ 12,308 Accrued benefit liability (included in pension and severance obligations) (47,124) (44,730) Net amount recognized at year end $ (35,085) $ (32,422)
Schedule of amounts recognized in other comprehensive income (loss)	The following table summarizes, by component, the change in accumulated other comprehensive income (loss), net of tax related to our Plans: Prior Service Actuarial Net Gain (Loss) Total (In thousands) Balance at December 31, 2021 $ 602 $ 5,014 $ 5,616 Amortization and settlement gain included in net periodic pension cost — (1,021) (1,021) Net gain (loss) arising during period — 9,625 9,625 Adjustments to unrealized components of defined benefit pension plan included in other comprehensive income (loss) — 8,604 8,604 Balance at December 31, 2022 $ 602 $ 13,618 $ 14,220 Amortization and settlement gain included in net periodic pension cost — (46) (46) Net gain (loss) arising during period — 1,731 1,731 Adjustments to unrealized components of defined benefit pension plan included in other comprehensive income (loss) — 1,685 1,685 Balance at December 31, 2023 $ 602 $ 15,303 $ 15,905
Schedule of benefit obligations in excess of fair value of plan assets	Information for pension plans with benefit obligations in excess of plan assets is as follows: December 31, 2023 2022 (In thousands) Plans with underfunded or non-funded projected benefit obligation: Aggregate projected benefit obligation $ 100,662 $ 96,310 Aggregate fair value of plan assets 53,539 51,581 Plans with underfunded or non-funded accumulated benefit obligation: Aggregate accumulated benefit obligation 60,638 61,764 Aggregate fair value of plan assets 21,304 20,740
Schedule of components of net periodic pension cost	The following table summarizes total pension expense: For the Year Ended December 31, 2023 2022 2021 (In thousands) Components of net periodic pension cost and total pension expense: Service cost $ 15,032 $ 20,072 $ 25,908 Interest cost 6,202 4,731 4,900 Expected return on plan assets (5,144) (5,605) (5,600) Recognized actuarial (gain) loss (156) 53 128 Net periodic pension cost 15,934 19,251 25,336 Curtailment (gain) loss (617) — (954) Settlement (gain) loss 132 (1,374) (743) Total pension expense $ 15,449 $ 17,877 $ 23,639
Schedule of assumptions used	The following table summarizes the weighted-average assumptions used in computing the net periodic pension cost and projected benefit obligations: For the Year Ended December 31, 2023 2022 2021 Discount rate for determining net periodic pension cost 4.2 % 2.6 % 2.3 % Discount rate for determining benefit obligations at December 31 3.8 % 4.2 % 2.6 % Rate of compensation increase for determining net periodic pension cost 3.6 % 3.7 % 3.7 % Rate of compensation increase for determining benefit obligations at December 31 3.7 % 3.6 % 3.7 % Expected rate of return on plan assets for determining net periodic 4.1 % 3.8 % 3.7 %
Schedule of allocation of plan assets	The current rate of return assumption targets are based on asset allocation strategies as follows: Allocation Debt Equity Other Japan defined benefit plan 64 % 34 % 2 % Korea defined benefit plan 30 % 20 % 50 % Philippine defined benefit plan 56 % 42 % 2 % The fair value of our pension plan assets, by asset category utilizing the fair value hierarchy as discussed in Note 16, is as follows: December 31, 2023 December 31, 2022 Level 1 Level 2 Total Level 1 Level 2 Total (In thousands) (In thousands) Cash and cash equivalents $ 217 $ — $ 217 $ 1,117 $ — $ 1,117 Equity securities 13,680 — 13,680 13,339 — 13,339 Debt securities Government bonds 3,674 — 3,674 2,982 — 2,982 Corporate bonds 1,130 — 1,130 540 — 540 Treasury notes 11,993 — 11,993 11,561 — 11,561 Mutual and commingled funds Equity funds 29,016 7,807 36,823 23,931 7,157 31,088 Debt funds 12,031 13,163 25,194 11,651 13,409 25,060 Guaranteed investment contracts — 23,189 23,189 — 28,340 28,340 Taiwan retirement fund 12,478 — 12,478 12,845 — 12,845 Other, net — 818 818 (383) 849 466 Total fair value of pension plan assets $ 84,219 $ 44,977 $ 129,196 $ 77,583 $ 49,755 $ 127,338
Schedule of expected benefit payments	The estimated future benefit payments related to our foreign defined benefit plans are as follows: Payments (In thousands) 2024 $ 9,369 2025 11,715 2026 12,383 2027 15,185 2028 16,062 2029 to 2033 98,940

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2023
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of accumulated other comprehensive income (loss)	The following table reflects the changes in accumulated other comprehensive income (loss), net of tax: Unrealized Gain (Losses) on Available-for-Sale Debt Investments (1) Defined Benefit Pension (2) Foreign Currency Translation Total (In thousands) Balance at December 31, 2021 $ (348) $ 5,616 $ 14,710 $ 19,978 Other comprehensive income (loss) before reclassifications (1,243) 9,625 (10,658) (2,276) Amounts reclassified from accumulated other comprehensive income (loss) 18 (1,021) — (1,003) Other comprehensive income (loss) (1,225) 8,604 (10,658) (3,279) Balance at December 31, 2022 $ (1,573) $ 14,220 $ 4,052 $ 16,699 Other comprehensive income (loss) before reclassifications 2,265 1,731 (3,819) 177 Amounts reclassified from accumulated other comprehensive income (loss) (480) (46) — (526) Other comprehensive income (loss) 1,785 1,685 (3,819) (349) Balance at December 31, 2023 $ 212 $ 15,905 $ 233 $ 16,350 (1) Amounts reclassified out of accumulated other comprehensive income (loss) are included as other (income) expense, net (Note 3). (2) 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 (Note 3).

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of fair value of derivative instruments in statement of financial position	As of December 31, 2023 and 2022, our foreign exchange forward contracts consisted of the following: December 31, 2023 December 31, 2022 Notional Value Fair Value (Level 2) Balance Sheet Location Notional Value Fair Value (Level 2) Balance Sheet Location (In thousands) Japanese yen $ 279,027 $ 2,745 Other current assets $ 330,179 $ 6,284 Other current assets Korean won 59,036 (97) Accrued expenses 65,927 333 Other current assets Philippine peso 6,553 (20) Accrued expenses 3,085 (6) Accrued expenses Singapore dollar 11,506 20 Other current assets — — N/A Taiwan dollar 37,914 89 Other current assets 28,763 (57) Accrued expenses Total forward contracts $ 394,036 $ 2,737 $ 427,954 $ 6,554

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of financial instruments that are not recorded at fair value	The following table presents the fair value of our debt: December 31, 2023 December 31, 2022 Fair Carrying Fair Carrying (In thousands) Senior notes (Level 1) $ 531,778 $ 521,839 $ 523,016 $ 521,114 Revolving credit facilities and term loans (Level 2) 666,316 681,617 686,728 711,220 Total financial instruments $ 1,198,094 $ 1,203,456 $ 1,209,744 $ 1,232,334

Business Segments, Customer C_2

Business Segments, Customer Concentrations and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Schedule of revenue from external customers by products and services	Net sales by product group consist of the following: For the Year Ended December 31, 2023 2022 2021 (In thousands) Advanced Products $ 5,032,859 $ 5,367,589 $ 4,409,207 Mainstream Products 1,470,206 1,723,996 1,729,122 Total net sales $ 6,503,065 $ 7,091,585 $ 6,138,329 (1) Advanced Products include flip chip, memory and wafer-level processing and related test services. (2) Mainstream Products include all other wirebond packaging and related test services. Net sales by end market consist of the following : For the Year Ended December 31, 2023 2022 2021 Communications (smartphones, tablets) 50 % 44 % 41 % Automotive, industrial and other (ADAS, electrification, infotainment, safety) 21 % 20 % 21 % Computing (data center, infrastructure, PC/laptop, storage) 16 % 16 % 16 % Consumer (AR & gaming, connected home, home electronics, wearables) 13 % 20 % 22 % Total net sales 100 % 100 % 100 %
Schedule of net sales by country, and property, plant and equipment by physical location	Net sales by region based on customer headquarters location consist of the following: For the Year Ended December 31, 2023 2022 2021 (In thousands) Europe, Middle East and Africa $ 1,043,880 $ 1,084,853 $ 1,061,369 Japan 935,620 1,132,121 1,253,717 Asia Pacific (excluding Japan) 704,520 1,017,246 999,591 Total foreign countries 2,684,020 3,234,220 3,314,677 United States 3,819,045 3,857,365 2,823,652 Total net sales $ 6,503,065 $ 7,091,585 $ 6,138,329
Schedule of disclosure on geographic areas, long-lived assets in individual foreign countries by country	Property, plant and equipment, net, based on physical location, consist of the following: December 31, 2023 2022 (In thousands) China $ 385,544 $ 476,945 Japan 143,399 121,842 Korea 1,781,632 1,868,956 Malaysia 51,164 41,978 Philippines 183,430 195,805 Portugal 108,982 82,454 Taiwan 272,428 261,449 Vietnam 365,059 79,630 Other foreign countries 272 583 Total foreign countries 3,291,910 3,129,642 United States 7,535 5,972 Total property, plant and equipment, net $ 3,299,445 $ 3,135,614

Description of Business and S_4

Description of Business and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Significant Accounting Policies [Line Items]
Assets	$ 6,771,125	$ 6,821,757
Liabilities	2,776,090	3,122,056
Long term finance lease liabilities	$ 47,800	$ 54,800
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Unbilled receivables	$ 260,800	$ 301,700
Contract with customer, liability	135,500	170,600
Contract with customer, liability, current	71,117	81,459
Contract with customer, liability, revenue recognized	$ 66,900	$ 101,200	$ 29,000
Minimum
Schedule of Significant Accounting Policies [Line Items]
Remaining lease term	1 year
Revenue, expected timing of satisfaction, period	1 year
Maximum
Schedule of Significant Accounting Policies [Line Items]
Remaining lease term	82 years
Revenue, expected timing of satisfaction, period	5 years
Largest Customer | Net sales | Customer Concentration Risk
Schedule of Significant Accounting Policies [Line Items]
Concentration risk (as a percent)	27.70%	20.60%	13.70%
Second Largest Customer | Net sales | Customer Concentration Risk
Schedule of Significant Accounting Policies [Line Items]
Concentration risk (as a percent)		10.10%
Variable Interest Entity, Primary Beneficiary
Schedule of Significant Accounting Policies [Line Items]
Ownership percentage	40%
Assets	$ 17,300
Liabilities	$ 100

Description of Business and S_5

Description of Business and Summary of Significant Accounting Policies (Summary of Property, Plant and Equipment) (Details)	Dec. 31, 2023
Buildings and improvements | Minimum
Summary of Significant Accounting Policies [Line Items]
Useful life	10 years
Buildings and improvements | Maximum
Summary of Significant Accounting Policies [Line Items]
Useful life	40 years
Machinery and equipment | Minimum
Summary of Significant Accounting Policies [Line Items]
Useful life	2 years
Machinery and equipment | Maximum
Summary of Significant Accounting Policies [Line Items]
Useful life	7 years
Software and computer equipment | Minimum
Summary of Significant Accounting Policies [Line Items]
Useful life	3 years
Software and computer equipment | Maximum
Summary of Significant Accounting Policies [Line Items]
Useful life	5 years
Furniture, fixtures and other equipment | Minimum
Summary of Significant Accounting Policies [Line Items]
Useful life	4 years
Furniture, fixtures and other equipment | Maximum
Summary of Significant Accounting Policies [Line Items]
Useful life	10 years

Share-Based Compensation Plan_2

Share-Based Compensation Plans (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) installment shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 18, 2021 shares	Jan. 02, 2008 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 8.3	$ 13.6	$ 11
Deferred income tax benefits for stock options and restricted stock	0.7	1.7	1.4
Total intrinsic value	$ 5.8	8	$ 17.7
Restricted shares vesting (as a percent)	8.33%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
Unrecognized compensation expense	$ 0.3
Weighted-average period	9 months 14 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Total fair value of vested restricted shares	$ 2.9
Restricted Stock [Member] | Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Time-Vested Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Award vesting installments | installment	4
Performance-Vested Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	2 years
Award vesting installments | installment	1
Period of earned awards become vested	90 days
Award performance measurement period	2 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 12.1
Weighted-average period	1 year 3 months 18 days
Total fair value of vested restricted shares	$ 11.6	$ 0.5
Minimum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Minimum | Performance-Vested Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage of target grant amount	0%
Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Maximum | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting (as a percent)	100%
Maximum | Performance-Vested Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage of target grant amount	200%
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares					17,000,000
Two Thousand Twenty-One Equity Incentive Plan Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares				23,100,000
Number of shares reserved for issuance (in shares) | shares				22,800,000
Number of shares available for grant (in shares) | shares	20,600,000

Share-Based Compensation Plan_3

Share-Based Compensation Plans (Stock Options) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Number of Shares
Outstanding beginning balance (in shares) | shares	2,376
Granted (in shares) | shares	0
Exercised (in shares) | shares	(345)
Forfeited or expired (in shares) | shares	0
Outstanding ending balance (in shares) | shares	2,031
Fully vested and expected to vest (in shares) | shares	2,029
Exercisable (in shares) | shares	1,973
Weighted-Average Exercise Price per Share
Outstanding beginning balance (in dollars per share) | $ / shares	$ 10.54
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	10.31
Forfeited or expired (in dollars per share) | $ / shares	0
Outstanding ending balance (in dollars per share) | $ / shares	10.58
Fully vested and expected to vest (in dollars per share) | $ / shares	10.58
Exercisable (in dollars per share) | $ / shares	$ 10.51
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding (years)	4 years 11 months 23 days
Fully vested and expected to vest (years)	4 years 11 months 23 days
Exercisable (years)	4 years 11 months 4 days
Outstanding ending balance (in dollars) | $	$ 46,068
Fully vested and expected to vest (in dollars) | $	46,029
Exercisable (in dollars) | $	$ 44,903

Share-Based Compensation Plan_4

Share-Based Compensation Plans (Restricted Shares and Restricted Stock Units Activity) (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted shares
Number of Shares
Nonvested beginning balance (in shares)	109
Awards granted (in shares)	0
Awards vested (in shares)	(109)
Awards forfeited (in shares)	0
Nonvested ending balance (in shares)	0	109
Weighted- average Grant Date Fair Value
Nonvested beginning balance (in dollars per share)	$ 15.38
Awards granted (in dollars per share)	0
Awards vested (in dollars per share)	15.38
Awards forfeited (in dollars per share)	0
Nonvested ending balance (in dollars per share)	$ 0	$ 15.38
Restricted Stock Units (RSUs)
Number of Shares
Nonvested beginning balance (in shares)	738	286	0
Awards granted (in shares)	1,049	531	295
Awards vested (in shares)	(464)	(22)	0
Awards forfeited (in shares)	(16)	(57)	(9)
Nonvested ending balance (in shares)	1,307	738	286
Weighted- average Grant Date Fair Value
Nonvested beginning balance (in dollars per share)	$ 22.34	$ 22.48	$ 0
Awards granted (in dollars per share)	26.72	22.29	22.48
Awards vested (in dollars per share)	22.19	22.23	0
Awards forfeited (in dollars per share)	25.24	22.63	22.58
Nonvested ending balance (in dollars per share)	$ 25.87	$ 22.34	$ 22.48

Other Income and Expense (Detai

Other Income and Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Income and Expenses [Abstract]
Interest income	$ (48,458)	$ (12,762)	$ (1,065)
Foreign currency (gain) loss, net	18,361	(1,572)	723
Loss on debt retirement	0	464	0
Other	(2,457)	(4,439)	(2,799)
Total other (income) expense, net	$ (32,554)	$ (18,309)	$ (3,141)

Income Taxes (Income Before Inc

Income Taxes (Income Before Income Tax, Domestic and Foreign) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Geographic sources of income (loss) before income taxes
United States	$ 94,643	$ 81,488	$ 81,994
Foreign	349,198	775,444	633,072
Income before taxes	$ 443,841	$ 856,932	$ 715,066

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 19,831	$ 40,063	$ 9,649
State	7	150	198
Foreign	48,478	61,300	48,936
Current income tax expense (benefit)	68,316	101,513	58,783
Deferred:
Federal	8,899	(10,156)	20,478
State	1	1,458	361
Foreign	4,494	(2,925)	(10,163)
Deferred income tax expense (benefit)	13,394	(11,623)	10,676
Income tax expense	$ 81,710	$ 89,890	$ 69,459

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Effective Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. federal statutory income tax rate	21%	21%	21%
Foreign income taxed at different rates	(4.20%)	(12.00%)	(9.50%)
Foreign exchange (loss) gain	0.50%	2.20%	(2.30%)
Change in valuation allowance	2.90%	(2.40%)	0.10%
Income tax credits generated	(7.50%)	(6.10%)	(5.10%)
Foreign earnings and profits	7%	9%	5.70%
Foreign derived intangible income	(1.60%)	(0.90%)	(1.10%)
Settlements and changes in uncertain tax positions	(0.50%)	(0.20%)	0.80%
Other	0.80%	(0.10%)	0.10%
Income tax expense	18.40%	10.50%	9.70%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Valuation allowance reversed		$ 17.8
Tax benefit from income tax holiday	$ 18.6	$ 84.5	$ 56.7
Benefit from income tax holiday on diluted earnings per share (in dollars per share)	$ 0.08	$ 0.34	$ 0.23
Repatriation of earnings estimated tax impact	$ 165.9
Unrecognized tax benefits, period decrease	1.7
Reductions from lapse of statutes of limitations	0.8
Liability for uncertain tax positions	23
Unrecognized tax benefits, reduction of deferred tax assets	8.5
Accrued and unpaid interest and penalties	$ 4.5	$ 4.9

Income Taxes (Components of Def

Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 33,679	$ 49,846
Tax credit carryforwards	88,147	92,368
Property, plant and equipment	21,387	15,328
Deferred interest expense	476	0
Accrued liabilities	37,832	39,929
Receivable	30,086	29,178
Unrealized foreign exchange loss	7,205	8,018
Revenue recognition	0	1,564
Operating lease liabilities	16,053	26,955
Other	15,219	14,665
Total deferred tax assets	250,084	277,851
Valuation allowance	(114,811)	(101,869)
Total deferred tax assets net of valuation allowance	135,273	175,982
Property, plant and equipment	34,206	50,215
Deferred gain	5,739	7,839
Unrealized foreign exchange gain	3,129	5,242
Unbilled receivables	8,995	822
Operating lease right of use assets	16,031	26,241
Other	5,533	7,433
Total deferred tax liabilities	73,633	97,792
Other assets	73,585	86,616
Other non-current liabilities	(11,945)	(8,426)
Net deferred tax assets	$ 61,640	$ 78,190

Income Taxes (Valuation Allowan

Income Taxes (Valuation Allowance) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Valuation Allowance [Line Items]
Total valuation allowance	$ 114,811	$ 101,869
United States
Valuation Allowance [Line Items]
Total valuation allowance	44,426	40,610
Foreign
Valuation Allowance [Line Items]
Total valuation allowance	$ 70,385	$ 61,259

Income Taxes (Net Operating Los

Income Taxes (Net Operating Loss Carryforwards) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
U.S. federal net operating loss carryforwards
Loss Carryforwards and other details [Abstract]
Operating loss carryforwards	$ 5,611	$ 13,003
U.S. state net operating loss carryforwards
Loss Carryforwards and other details [Abstract]
Operating loss carryforwards	32,612	38,384
Foreign net operating loss carryforwards
Loss Carryforwards and other details [Abstract]
Operating loss carryforwards	$ 196,636	$ 240,740

Income Taxes (Tax Credit Carryf

Income Taxes (Tax Credit Carryforwards) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
U.S. Federal | U.S. Foreign Tax Credits
Tax Credit Carryforward [Line Items]
Foreign Tax Credits	$ 51,512	$ 54,130
U.S. Federal | U.S. Other Tax Credits
Tax Credit Carryforward [Line Items]
Foreign Tax Credits	2,559	110
Foreign
Tax Credit Carryforward [Line Items]
Foreign Tax Credits	$ 34,546	$ 38,128

Income Taxes (Unrecognized Tax

Income Taxes (Unrecognized Tax Benefits - Rollforward and Discussion) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, beginning of period	$ 33,253	$ 37,293	$ 32,598
Additions based on tax positions related to the current year	0	1,519	9,562
Additions for tax positions of prior years	495	1,909	1,740
Reductions for tax positions of prior years	(345)	(5,755)	(66)
Reductions related to settlements with tax authorities	0	(988)	(1,266)
Reductions from lapse of statutes of limitations	(1,866)	(725)	(5,275)
Balance, end of period	$ 31,537	$ 33,253	$ 37,293

Earnings Per Share (Calculation

Earnings Per Share (Calculation of EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net income attributable to Amkor common stockholders, basic	$ 359,813	$ 765,823	$ 642,995
Net income attributable to Amkor common stockholders, diluted	$ 359,813	$ 765,823	$ 642,995
Weighted-average number of common shares outstanding — basic (in shares)	245,628	244,676	243,878
Effect of dilutive securities:
Share-based awards (in shares)	1,548	1,529	1,826
Weighted-average number of common shares outstanding — diluted (in shares)	247,176	246,205	245,704
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 1.46	$ 3.13	$ 2.64
Diluted (in dollars per share)	$ 1.46	$ 3.11	$ 2.62

Earnings Per Share (Potential S

Earnings Per Share (Potential Shares of Common Stock Excluded from Diluted EPS (Details) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Share-based awards (in shares)	2	180	112

Investments (Summary of Cash Eq

Investments (Summary of Cash Equivalents, and Short term Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	$ 581,367
Short-term investments, fair value	581,573
Total, amortized cost	581,367	$ 474,794
Total, gross unrealized gains	615	19
Total, gross unrealized losses	(409)	(1,692)
Total, fair value	581,573	473,121
Proceeds from sale of cash equivalent investments	47,000	29,600	$ 12,800
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	469,451	279,268
Short-term investments, gross unrealized gains	615	15
Short-term investments, gross unrealized losses	(409)	(1,692)
Short-term investments, fair value	469,657	277,591
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	65,340	25,677
Short-term investments, gross unrealized gains	170	7
Short-term investments, gross unrealized losses	(22)	(134)
Short-term investments, fair value	65,488	25,550
Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	17,086	17,362
Short-term investments, gross unrealized gains	0	0
Short-term investments, gross unrealized losses	0	0
Short-term investments, fair value	17,086	17,362
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	56,273	27,866
Short-term investments, gross unrealized gains	0	0
Short-term investments, gross unrealized losses	0	0
Short-term investments, fair value	56,273	27,866
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	251,671	198,868
Short-term investments, gross unrealized gains	432	7
Short-term investments, gross unrealized losses	(299)	(1,529)
Short-term investments, fair value	251,804	197,346
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost		996
Short-term investments, gross unrealized gains		0
Short-term investments, gross unrealized losses		(4)
Short-term investments, fair value		992
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost		696
Short-term investments, gross unrealized gains		0
Short-term investments, gross unrealized losses		(2)
Short-term investments, fair value		694
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost		364
Short-term investments, gross unrealized gains		0
Short-term investments, gross unrealized losses		(2)
Short-term investments, fair value		362
U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	13,200	735
Short-term investments, gross unrealized gains	0	0
Short-term investments, gross unrealized losses	(9)	(1)
Short-term investments, fair value	13,191	734
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, amortized cost	65,881	6,704
Short-term investments, gross unrealized gains	13	1
Short-term investments, gross unrealized losses	(79)	(20)
Short-term investments, fair value	65,815	6,685
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost	111,916	195,526
Cash equivalents, gross unrealized gains	0	4
Cash equivalents, gross unrealized losses	0	0
Cash equivalent, fair value	111,916	195,530
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost	138	25
Cash equivalents, gross unrealized gains	0	0
Cash equivalents, gross unrealized losses	0	0
Cash equivalent, fair value	138	25
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost	48,063	69,101
Cash equivalents, gross unrealized gains	0	0
Cash equivalents, gross unrealized losses	0	0
Cash equivalent, fair value	48,063	69,101
Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost	60,719	97,650
Cash equivalents, gross unrealized gains	0	0
Cash equivalents, gross unrealized losses	0	0
Cash equivalent, fair value	60,719	97,650
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost		1,001
Cash equivalents, gross unrealized gains		0
Cash equivalents, gross unrealized losses		0
Cash equivalent, fair value		1,001
U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost	2,996	10,767
Cash equivalents, gross unrealized gains	0	1
Cash equivalents, gross unrealized losses	0	0
Cash equivalent, fair value	2,996	10,768
U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalents, amortized cost		16,982
Cash equivalents, gross unrealized gains		3
Cash equivalents, gross unrealized losses		0
Cash equivalent, fair value		16,985
Level 1
Debt Securities, Available-for-sale [Line Items]
Total, fair value	146,616	132,465
Level 1 | Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	82,901	24,047
Level 1 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	0	0
Level 1 | Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	17,086	17,362
Level 1 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	0	0
Level 1 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	0	0
Level 1 | Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value		0
Level 1 | Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value		0
Level 1 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value		0
Level 1 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	0	0
Level 1 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	65,815	6,685
Level 1 | Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	63,715	108,418
Level 1 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	0	0
Level 1 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	0	0
Level 1 | Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	60,719	97,650
Level 1 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value		0
Level 1 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	2,996	10,768
Level 1 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value		0
Level 2
Debt Securities, Available-for-sale [Line Items]
Total, fair value	434,957	340,656
Level 2 | Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	386,756	253,544
Level 2 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	65,488	25,550
Level 2 | Certificate of deposits
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	0	0
Level 2 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	56,273	27,866
Level 2 | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	251,804	197,346
Level 2 | Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value		992
Level 2 | Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value		694
Level 2 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value		362
Level 2 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	13,191	734
Level 2 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Short-term investments, fair value	0	0
Level 2 | Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	48,201	87,112
Level 2 | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	138	25
Level 2 | Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	48,063	69,101
Level 2 | Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	0	0
Level 2 | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value		1,001
Level 2 | U.S. government bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value	$ 0	0
Level 2 | U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Cash equivalent, fair value		$ 16,985

Investments (Contractual Maturi

Investments (Contractual Maturities of Cash Equivalents and Available-for-Sale Debt Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Within 1 year, Amortized Cost	$ 406,551
After 1 year through 5 years, Amortized Cost	109,338
Short-term investments, amortized cost	581,367
Within 1 year, Fair Value	406,346
After 1 year through 5 years, Fair Value	109,601
Short-term investments, fair value	581,573
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Asset-backed securities, Amortized Cost	65,478
Short-term investments, amortized cost	65,340	$ 25,677
Asset-backed securities, Fair Value	65,626
Short-term investments, fair value	$ 65,488	$ 25,550

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost of held-to-maturity securities	$ 5.2	$ 4.4
Level 1
Debt and Equity Securities, FV-NI [Line Items]
Fair market value of held-to-maturity securities		$ 4.3

Factoring of Accounts Receiva_2

Factoring of Accounts Receivable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Total Factored
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 253.9	$ 386.5
Factoring Fees
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 1.3	$ 1.1

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Finance lease assets	$ 209,506	$ 165,122
Total property, plant and equipment	9,971,780	9,371,331
Accumulated depreciation and amortization	(6,672,335)	(6,235,717)
Total property, plant and equipment, net	3,299,445	3,135,614
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	212,722	214,763
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	2,080,589	1,817,135
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	7,022,614	6,757,652
Furniture, fixtures and other equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	22,655	23,240
Software and computer equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	200,362	240,610
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 223,332	$ 152,809

Property, Plant and Equipment_3

Property, Plant and Equipment (Summary of Depreciation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 630,941	$ 612,105	$ 562,962

Property, Plant and Equipment_4

Property, Plant and Equipment (Narrative) (Details) - Vietnam $ in Millions	1 Months Ended
	Oct. 31, 2023 USD ($)
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, transferred amount	$ (244.3)
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, transferred amount	$ 244.3

Leases (Components of Lease Exp

Leases (Components of Lease Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease cost	$ 70,722	$ 81,410	$ 64,902
Amortization of leased assets	42,345	24,644	14,196
Interest on lease liabilities	5,521	3,891	2,768
Total finance lease cost	47,866	28,535	16,964
Short-term lease cost	4,788	5,749	6,264
Variable lease cost	6,921	6,592	7,409
Net lease cost	130,297	122,286	95,539
Operating cash flows for operating leases	73,774	81,044	64,786
Operating cash flows for finance leases	5,419	3,933	1,745
Financing cash flows for finance leases	$ 66,398	$ 40,673	$ 20,373
Weighted average remaining lease term, Operating leases	6 years 1 month 6 days	4 years 2 months 12 days	3 years 2 months 12 days
Weighted average remaining lease term, Finance leases	3 years 2 months 12 days	2 years 3 months 18 days	3 years 1 month 6 days
Weighted average discount rate, Operating leases	5.20%	4.40%	3.60%
Weighted average discount rate, Finance leases	5.70%	4.10%	3.20%

Leases (Future Minimum Lease Pa

Leases (Future Minimum Lease Payments) (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Operating Leases
2024	$ 36,916
2025	19,869
2026	12,752
2027	9,144
2028	6,017
Thereafter	20,488
Total future minimum lease payments	105,186
Less: Imputed interest	(14,733)
Total	90,453
Finance Leases
2024	62,306
2025	25,259
2026	11,436
2027	3,568
2028	2,511
Thereafter	12,913
Total future minimum lease payments	117,993
Less: Imputed interest	(12,438)
Total	$ 105,555

Leases (Narrative) (Details)

Leases (Narrative) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Leases [Abstract]
Amount of leases not yet commenced	$ 8

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Payroll and benefits	$ 115,604	$ 137,445
Deferred revenue and customer advances	71,117	81,459
Short-term finance lease liability	$ 57,761	$ 56,570
Finance lease, liability, current, statement of financial position	Total accrued expenses	Total accrued expenses
Income taxes payable	$ 35,215	$ 50,685
Accrued interest	11,175	10,878
Accrued severance plan obligations (Note 12)	7,906	7,422
Other accrued expenses	59,636	57,382
Total accrued expenses	$ 358,414	$ 401,841

Debt (Long Term Debt) (Details)

Debt (Long Term Debt) (Details) $ in Thousands, ¥ in Billions	1 Months Ended		12 Months Ended
	Dec. 31, 2023 USD ($) installment	Dec. 31, 2023 JPY (¥) installment	Dec. 31, 2023 USD ($)	Dec. 31, 2023 KRW (₩)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Apr. 30, 2021 KRW (₩) borrowing
Debt Instrument [Line Items]
Total debt	$ 1,209,785		$ 1,209,785		$ 1,239,772
Less: Unamortized discount and deferred debt costs, net	(6,329)		(6,329)		(7,438)
Less: Short-term borrowings and current portion of long-term debt	(131,624)		(131,624)		(143,813)
Long-term debt	$ 1,071,832		$ 1,071,832		1,088,521
6.625% Senior notes, due September 2027 | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percent)	6.625%		6.625%	6.625%
Total debt	$ 525,000		$ 525,000		525,000
Term Loan fixed rate at 1.85% due April 2024 | Subsidiary Term Loans | Korea
Debt Instrument [Line Items]
Interest rate (as a percent)	1.85%		1.85%	1.85%
Total debt	$ 0		$ 0		0
Amount of debt agreement | ₩								₩ 80,000,000,000
Number of annual borrowings | borrowing								6
Amount of unused borrowing capacity	$ 62,000		$ 62,000	₩ 80,000,000,000
Term loan, fixed rate at 2.12%, due December 2028 | Subsidiary Term Loans | Korea
Debt Instrument [Line Items]
Interest rate (as a percent)	2.12%		2.12%	2.12%
Total debt	$ 200,000		$ 200,000		200,000
Short-term term loans, variable rate | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Total debt	5,098		5,098		4,042
Amount of unused borrowing capacity	$ 7,700		$ 7,700
Term loan, fixed rate at 1.30%, due July 2023 | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Interest rate (as a percent)	1.30%		1.30%	1.30%
Total debt	$ 0		$ 0		29,744
Term loan, fixed rate at 1.35%, due December 2024 | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Interest rate (as a percent)	1.35%		1.35%	1.35%
Total debt	$ 40,414		$ 40,414		86,943
Term loan, fixed rate at 1.20%, due December 2025 | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Interest rate (as a percent)	1.20%		1.20%	1.20%
Total debt	$ 30,913		$ 30,913		49,878
Term loan, fixed rate at 1.23%, due December 2026 | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Interest rate (as a percent)	1.23%		1.23%	1.23%
Total debt	$ 55,729		$ 55,729		79,927
Term loan, fixed rate at 1.59%, due December 2027 | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Interest rate (as a percent)	1.59%		1.59%	1.59%
Total debt	$ 89,053		$ 89,053		119,738
Term loan, fixed rate at 1.80%, due December 2028 | Subsidiary Term Loans | Japan
Debt Instrument [Line Items]
Interest rate (as a percent)	1.80%		1.80%	1.80%
Total debt	$ 124,078		$ 124,078		0
Proceeds from issuance of long-term debt	$ 123,300	¥ 17.5
Number of quarterly installments | installment	20	20
Term Loan, SOFR Plus 0.75% Due March 2024 | Subsidiary Term Loans | China
Debt Instrument [Line Items]
Total debt	$ 0		$ 0		46,000
Term Loan, SOFR Plus 0.75% Due March 2024 | Subsidiary Term Loans | China | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)			0.75%
Term Loan, SOFR Plus 0.75% Due June 2025 | Subsidiary Term Loans | China
Debt Instrument [Line Items]
Total debt	37,000		$ 37,000		39,000
Term Loan, SOFR Plus 0.75% Due June 2025 | Subsidiary Term Loans | China | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)			0.75%
Term Loan, SOFR Plus 0.75% Due 2025 | Subsidiary Term Loans | China
Debt Instrument [Line Items]
Total debt	57,500		$ 57,500		59,500
Term Loan, SOFR Plus 0.75% Due 2025 | Subsidiary Term Loans | China | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)			0.75%
Term Loans, SOFR Plus 1.40%, Due December 2026 | Subsidiary Term Loans | China
Debt Instrument [Line Items]
Total debt	45,000		$ 45,000		0
Periodic principal payment	500
Term Loans, SOFR Plus 1.40%, Due December 2026 | Subsidiary Term Loans | China | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)			1.40%
Credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) | Line of Credit | Taiwan | Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	0		$ 0		0
Amount of unused borrowing capacity	$ 15,000		$ 15,000
Credit facility, borrowing capacity						$ 15,000	$ 36,000
Senior secured revolving credit facility, applicable bank rate plus 1.75%, due March 2027 (Singapore) | Line of Credit | Singapore | Revolving Credit Facility
Debt Instrument [Line Items]
Interest rate (as a percent)	1.75%		1.75%	1.75%
Total debt	$ 0		$ 0		$ 0
Credit facility, borrowing capacity						600,000
Credit facility, base amount						$ 250,000
Credit facility percentage of variable borrowings						37.50%
Remaining borrowing capacity	$ 600,000		$ 600,000

Debt (Narrative) (Details)

Debt (Narrative) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Collateralized debt	$ 679.7
Asset Pledged as Collateral
Debt Instrument [Line Items]
Collateralized debt	$ 326.5

Debt (Interest Rates) (Details)

Debt (Interest Rates) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Japan | Short-term term loans, variable rate | Subsidiary Term Loans
Debt Instrument [Line Items]
Interest rate at end of period (as a percent)	0.24%	0.29%
China | Term Loan, SOFR Plus 0.75% Due March 2024 | Subsidiary Term Loans
Debt Instrument [Line Items]
Interest rate at end of period (as a percent)	0%	5.83%
China | Term Loan, SOFR Plus 0.75% Due March 2024 | Subsidiary Term Loans | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)	0.75%
China | Term Loan, SOFR Plus 0.75% Due June 2025 | Subsidiary Term Loans
Debt Instrument [Line Items]
Interest rate at end of period (as a percent)	6.07%	5.55%
China | Term Loan, SOFR Plus 0.75% Due June 2025 | Subsidiary Term Loans | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)	0.75%
China | Term Loan, SOFR Plus 0.75% Due 2025 | Subsidiary Term Loans
Debt Instrument [Line Items]
Interest rate at end of period (as a percent)	6.07%	5.48%
China | Term Loan, SOFR Plus 0.75% Due 2025 | Subsidiary Term Loans | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)	0.75%
China | Term Loans, SOFR Plus 1.40%, Due December 2026 | Subsidiary Term Loans
Debt Instrument [Line Items]
Interest rate at end of period (as a percent)	6.76%	0%
China | Term Loans, SOFR Plus 1.40%, Due December 2026 | Subsidiary Term Loans | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Interest rate spread (as a percent)	1.40%

Debt (Maturities) (Details)

Debt (Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2024	$ 131,624
2025	222,612
2026	158,655
2027	622,079
2028	74,815
Thereafter	0
Total debt	$ 1,209,785	$ 1,239,772

Pension and Severance Plans (Ko

Pension and Severance Plans (Korean Severance Plan) (Details) - Korean Severance Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred Compensation Liability, Current and Noncurrent [Roll Forward]
Balance at beginning of the year	$ 56,289	$ 73,345
Provision of severance benefits	1,653	2,119
Severance payments	(8,770)	(15,295)
Foreign currency (gain) loss	(1,266)	(3,880)
Balance at the end of year	47,906	56,289
Payments remaining with the National Pension Fund	(119)	(124)
Total accrued severance plan obligations at December 31	47,787	56,165
Less current portion of accrued severance plan obligations (Note 10)	7,906	7,422
Non-current portion of accrued severance plan obligations	$ 39,881	$ 48,743

Pension and Severance Plans (De

Pension and Severance Plans (Defined Benefit Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in projected benefit obligation:
Projected benefit obligation at January 1	$ 159,760	$ 200,187
Service cost	15,032	20,072	$ 25,908
Interest cost	6,202	4,731	4,900
Benefits paid	(14,056)	(8,573)
Actuarial (gain) loss	4,150	(24,571)
Effects of curtailment	(617)	508
Settlement	(1,073)	(16,914)
Foreign exchange (gain) loss	(5,117)	(15,680)
Projected benefit obligation at December 31	164,281	159,760	200,187
Change in plan assets:
Fair value of plan assets at January 1	127,338	157,012
Actual gain (loss) on plan assets	12,325	(6,528)
Employer contributions	7,368	12,946
Settlement	(1,073)	(16,914)
Benefits paid	(14,056)	(8,573)
Foreign exchange gain (loss)	(2,706)	(10,605)
Fair value of plan assets at December 31	129,196	127,338	$ 157,012
Funded status of the Plans at December 31	$ (35,085)	$ (32,422)

Pension and Severance Plans (_2

Pension and Severance Plans (Defined Benefit Plans - Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Prepaid benefit cost (included in non-current assets)	$ 12,039	$ 12,308
Accrued benefit liability (included in pension and severance obligations)	(47,124)	(44,730)
Net amount recognized at year end	$ (35,085)	$ (32,422)

Pension and Severance Plans (Na

Pension and Severance Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Accumulated benefit obligation	$ 128.3	$ 125.6
Expected contributions in next fiscal year	11
Cost recognized	$ 27	$ 24.2	$ 21.8
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Immediate Recognition of Actuarial Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)

Pension and Severance Plans (Im

Pension and Severance Plans (Impact on Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 3,699,701	$ 2,972,546	$ 2,353,959
Amortization and settlement gain included in net periodic pension cost	(526)	(1,003)
Net gain (loss) arising during period	177	(2,276)
Total other comprehensive income (loss)	(349)	(3,279)	(7,292)
Balance at end of period	3,995,035	3,699,701	2,972,546
Prior Service Cost
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	602	602
Amortization and settlement gain included in net periodic pension cost	0	0
Net gain (loss) arising during period	0	0
Total other comprehensive income (loss)	0	0
Balance at end of period	602	602	602
Actuarial Net Gain (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	13,618	5,014
Amortization and settlement gain included in net periodic pension cost	(46)	(1,021)
Net gain (loss) arising during period	1,731	9,625
Total other comprehensive income (loss)	1,685	8,604
Balance at end of period	15,303	13,618	5,014
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	14,220	5,616
Amortization and settlement gain included in net periodic pension cost	(46)	(1,021)
Net gain (loss) arising during period	1,731	9,625
Total other comprehensive income (loss)	1,685	8,604
Balance at end of period	$ 15,905	$ 14,220	$ 5,616

Pension and Severance Plans (Be

Pension and Severance Plans (Benefit Obligations in Excess of Fair Value of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Plans with underfunded or non-funded projected benefit obligation:
Aggregate projected benefit obligation	$ 100,662	$ 96,310
Aggregate fair value of plan assets	53,539	51,581
Plans with underfunded or non-funded accumulated benefit obligation:
Aggregate accumulated benefit obligation	60,638	61,764
Aggregate fair value of plan assets	$ 21,304	$ 20,740

Pension and Severance Plans (Ch

Pension and Severance Plans (Changes and Components) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Service cost	$ 15,032	$ 20,072	$ 25,908
Interest cost	6,202	4,731	4,900
Expected return on plan assets	(5,144)	(5,605)	(5,600)
Recognized actuarial (gain) loss	(156)	53	128
Net periodic pension cost	15,934	19,251	25,336
Curtailment (gain) loss	(617)	0	(954)
Settlement (gain) loss	132	(1,374)	(743)
Total pension expense	$ 15,449	$ 17,877	$ 23,639

Pension and Severance Plans (Su

Pension and Severance Plans (Summarizes The Weighted-average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Discount rate for determining net periodic pension cost (as a percent)	4.20%	2.60%	2.30%
Discount rate for determining benefit obligations at December 31 (as a percent)	3.80%	4.20%	2.60%
Rate of compensation increase for determining net periodic pension cost (as a percent)	3.60%	3.70%	3.70%
Rate of compensation increase for determining benefit obligations at December 31 (as a percent)	3.70%	3.60%	3.70%
Expected rate of return on plan assets for determining net periodic pension cost (as a percent)	4.10%	3.80%	3.70%

Pension and Severance Plans (_3

Pension and Severance Plans (Defined Benefit Plans - Allocation of plan assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 129,196	$ 127,338	$ 157,012
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	84,219	77,583
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44,977	49,755
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	217	1,117
Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	217	1,117
Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,680	13,339
Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,680	13,339
Equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,674	2,982
Government bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,674	2,982
Government bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,130	540
Corporate bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,130	540
Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Treasury notes
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,993	11,561
Treasury notes | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,993	11,561
Treasury notes | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36,823	31,088
Equity funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,016	23,931
Equity funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,807	7,157
Debt funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25,194	25,060
Debt funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,031	11,651
Debt funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,163	13,409
Guaranteed investment contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23,189	28,340
Guaranteed investment contracts | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Guaranteed investment contracts | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23,189	28,340
Taiwan retirement fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,478	12,845
Taiwan retirement fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,478	12,845
Taiwan retirement fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other, net
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	818	466
Other, net | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	(383)
Other, net | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 818	$ 849
Japan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	64%
Japan | Other, net
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	2%
Japan | Equity funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	34%
Korea | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	30%
Korea | Other, net
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	50%
Korea | Equity funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	20%
Philippines | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	56%
Philippines | Other, net
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	2%
Philippines | Equity funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	42%

Pension and Severance Plans (_4

Pension and Severance Plans (Defined Benefit Plans - Expected Future Contributions and Other Disclosures) (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2024	$ 9,369
2025	11,715
2026	12,383
2027	15,185
2028	16,062
2029 to 2033	$ 98,940

Dividends (Details)

Dividends (Details) - $ / shares	1 Months Ended	12 Months Ended
	Nov. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity [Abstract]
Dividends per share, declared (in dollars per share)	$ 0.07875	$ 0.30375	$ 0.225	$ 0.17
Increase of quarterly dividends, percentage	5%

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 3,699,701	$ 2,972,546	$ 2,353,959
Other comprehensive income (loss) before reclassifications	177	(2,276)
Amounts reclassified from accumulated other comprehensive income (loss)	(526)	(1,003)
Total other comprehensive income (loss)	(349)	(3,279)	(7,292)
Balance at end of period	3,995,035	3,699,701	2,972,546
Unrealized Gain (Losses) on Available-for-Sale Debt Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(1,573)	(348)
Other comprehensive income (loss) before reclassifications	2,265	(1,243)
Amounts reclassified from accumulated other comprehensive income (loss)	(480)	18
Total other comprehensive income (loss)	1,785	(1,225)
Balance at end of period	212	(1,573)	(348)
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	14,220	5,616
Other comprehensive income (loss) before reclassifications	1,731	9,625
Amounts reclassified from accumulated other comprehensive income (loss)	(46)	(1,021)
Total other comprehensive income (loss)	1,685	8,604
Balance at end of period	15,905	14,220	5,616
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	4,052	14,710
Other comprehensive income (loss) before reclassifications	(3,819)	(10,658)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	(3,819)	(10,658)
Balance at end of period	233	4,052	14,710
AOCI, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	16,699	19,978	27,270
Total other comprehensive income (loss)	(349)	(3,279)	(7,292)
Balance at end of period	$ 16,350	$ 16,699	$ 19,978

Derivatives (Fair Value Of Deri

Derivatives (Fair Value Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets, Current	Other Assets, Current
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities, Current	Accrued Liabilities, Current
Foreign Exchange Forward
Derivatives, Fair Value [Line Items]
Notional Value	$ 394,036	$ 427,954
Foreign Exchange Forward | Level 2
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	2,737	6,554
Foreign Exchange Forward | Japanese yen
Derivatives, Fair Value [Line Items]
Notional Value	279,027	330,179
Foreign Exchange Forward | Japanese yen | Level 2
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	2,745	6,284
Foreign Exchange Forward | Korean won
Derivatives, Fair Value [Line Items]
Notional Value	59,036	65,927
Foreign Exchange Forward | Korean won | Level 2
Derivatives, Fair Value [Line Items]
Derivative assets, fair value		333
Derivative liabilities, fair value	(97)
Foreign Exchange Forward | Philippine peso
Derivatives, Fair Value [Line Items]
Notional Value	6,553	3,085
Foreign Exchange Forward | Philippine peso | Level 2
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	(20)	(6)
Foreign Exchange Forward | Singapore dollar
Derivatives, Fair Value [Line Items]
Notional Value	11,506
Foreign Exchange Forward | Singapore dollar | Level 2
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	20
Foreign Exchange Forward | Taiwan dollar
Derivatives, Fair Value [Line Items]
Notional Value	37,914	28,763
Foreign Exchange Forward | Taiwan dollar | Level 2
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	$ 89
Derivative liabilities, fair value		$ (57)

Derivatives (Narrative) (Detail

Derivatives (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net Loss on derivative	$ 38.6	$ 60.2	$ 58.8

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial instruments	$ 1,198,094	$ 1,209,744
Fair Value | Senior notes (Level 1) | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial instruments	531,778	523,016
Fair Value | Revolving credit facilities and term loans (Level 2) | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial instruments	666,316	686,728
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial instruments	1,203,456	1,232,334
Carrying Value | Senior notes (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial instruments	521,839	521,114
Carrying Value | Revolving credit facilities and term loans (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial instruments	$ 681,617	$ 711,220

Business Segments, Customer C_3

Business Segments, Customer Concentrations and Geographic Information (Net Sales by Product Group) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net sales	$ 6,503,065	$ 7,091,585	$ 6,138,329
Net sales | Product Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)	100%	100%	100%
Advanced Products
Segment Reporting Information [Line Items]
Net sales	$ 5,032,859	$ 5,367,589	$ 4,409,207
Mainstream Products
Segment Reporting Information [Line Items]
Net sales	$ 1,470,206	$ 1,723,996	$ 1,729,122
Communications (smartphones, tablets) | Net sales | Product Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)	50%	44%	41%
Automotive, industrial and other (ADAS, electrification, infotainment, safety) | Net sales | Product Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)	21%	20%	21%
Computing (data center, infrastructure, PC/laptop, storage) | Net sales | Product Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)	16%	16%	16%
Consumer (AR & gaming, connected home, home electronics, wearables) | Net sales | Product Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)	13%	20%	22%

Business Segments, Customer C_4

Business Segments, Customer Concentrations and Geographic Information (Net Sales by Region) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net sales	$ 6,503,065	$ 7,091,585	$ 6,138,329
Europe, Middle East and Africa
Segment Reporting Information [Line Items]
Net sales	1,043,880	1,084,853	1,061,369
Japan
Segment Reporting Information [Line Items]
Net sales	935,620	1,132,121	1,253,717
Asia Pacific (excluding Japan)
Segment Reporting Information [Line Items]
Net sales	704,520	1,017,246	999,591
Total foreign countries
Segment Reporting Information [Line Items]
Net sales	2,684,020	3,234,220	3,314,677
United States
Segment Reporting Information [Line Items]
Net sales	$ 3,819,045	$ 3,857,365	$ 2,823,652

Business Segments, Customer C_5

Business Segments, Customer Concentrations and Geographic Information (Narrative) (Details) - segment	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Number of operating segments	1
Largest Customer | Net sales | Customer Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)	27.70%	20.60%	13.70%
Second Largest Customer | Net sales | Customer Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk (as a percent)		10.10%

Business Segments, Customer C_6

Business Segments, Customer Concentrations and Geographic Information (Property, Plant and Equipment, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 3,299,445	$ 3,135,614
China
Segment Reporting Information [Line Items]
Property, plant and equipment, net	385,544	476,945
Japan
Segment Reporting Information [Line Items]
Property, plant and equipment, net	143,399	121,842
Korea
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,781,632	1,868,956
Malaysia
Segment Reporting Information [Line Items]
Property, plant and equipment, net	51,164	41,978
Philippines
Segment Reporting Information [Line Items]
Property, plant and equipment, net	183,430	195,805
Portugal
Segment Reporting Information [Line Items]
Property, plant and equipment, net	108,982	82,454
Taiwan
Segment Reporting Information [Line Items]
Property, plant and equipment, net	272,428	261,449
Vietnam
Segment Reporting Information [Line Items]
Property, plant and equipment, net	365,059	79,630
Other foreign countries
Segment Reporting Information [Line Items]
Property, plant and equipment, net	272	583
Total foreign countries
Segment Reporting Information [Line Items]
Property, plant and equipment, net	3,291,910	3,129,642
United States
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 7,535	$ 5,972

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 101,869	$ 122,357	$ 121,310
Additions (Credited) Charged to Expense	15,838	(17,762)	3,653
Write-offs	(2,896)	(2,726)	(2,606)
Balance at End of Period	$ 114,811	$ 101,869	$ 122,357