$AMKR
AMKOR TECHNOLOGY, INC. Stock $amkr

$amkr Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000104712721000010 Filed on February 19, 2021

Income Statement

Concept	2020 Q4	2019 Q4	2019 Q3
Revenue	$1.371B	$1.178B	$1.084B
YoY Change	16.34%	8.99%	-5.27%
Cost Of Revenue	$1.084B	$955.5M	$901.7M
YoY Change	13.45%	6.3%	-4.43%
Gross Profit	$278.5M	$223.0M	$182.2M
YoY Change	24.9%	22.27%	-9.2%
Gross Profit Margin	20.31%	18.92%	16.81%
Selling, General & Admin	$78.20M	$75.10M	$70.46M
YoY Change	4.13%	8.21%	-0.01%
% of Gross Profit	28.08%	33.68%	38.66%
Research & Development	$41.10M	$32.80M	$32.93M
YoY Change	25.3%	-12.77%	-12.29%
% of Gross Profit	14.76%	14.71%	18.07%
Depreciation & Amortization	$132.7M	$126.2M	$128.8M
YoY Change	5.15%	-11.62%	-10.11%
% of Gross Profit	47.65%	56.6%	70.7%
Operating Expenses	$119.4M	$107.9M	$103.4M
YoY Change	10.66%	0.84%	-4.28%
Operating Profit	$159.2M	$118.4M	$78.86M
YoY Change	34.46%	57.05%	-14.94%
Interest Expense	-$17.50M	-$18.50M	$16.99M
YoY Change	-5.41%	-4.15%	-14.07%
% of Operating Profit	-10.99%	-15.63%	21.54%
Other Income/Expense, Net	$100.0K	$700.0K	-$15.23M
YoY Change	-85.71%	-65.0%	-27.78%
Pretax Income	$139.6M	$100.6M	$63.63M
YoY Change	38.77%	74.35%	-11.16%
Income Tax	$12.68M	$764.0K	$9.141M
% Of Pretax Income	9.08%	0.76%	14.37%
Net Earnings	$126.7M	$99.15M	$54.07M
YoY Change	27.76%	250.4%	-4.57%
Net Earnings / Revenue	9.24%	8.41%	4.99%
Basic Earnings Per Share	$0.52	$0.41	$0.23
Diluted Earnings Per Share	$0.52	$0.41	$0.23
COMMON SHARES
Basic Shares Outstanding	242.4M shares	239.8M shares	239.6M shares
Diluted Shares Outstanding			239.9M shares

Balance Sheet

Concept	2020 Q4	2019 Q4	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$831.8M	$894.9M	$598.8M
YoY Change	-7.05%	31.29%	9.33%
Cash & Equivalents	$698.0M	$894.9M	$598.8M
Short-Term Investments	$133.8M
Other Short-Term Assets	$40.22M	$28.27M	$41.89M
YoY Change	42.25%	-11.66%	18.92%
Inventory	$297.3M	$220.6M	$216.7M
Prepaid Expenses
Receivables	$962.6M	$850.8M	$803.1M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$2.133B	$2.002B	$1.663B
YoY Change	6.56%	19.77%	3.21%
LONG-TERM ASSETS
Property, Plant & Equipment	$2.566B	$2.405B	$2.466B
YoY Change	6.7%	-9.27%	-9.14%
Goodwill	$27.33M	$25.98M	$26.10M
YoY Change	5.19%	1.0%	5.2%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets	$145.6M	$111.7M	$106.4M
YoY Change	30.34%	-22.5%	-24.76%
Total Long-Term Assets	$2.889B	$2.694B	$2.743B
YoY Change	7.25%	-4.61%	-4.9%
TOTAL ASSETS
Total Short-Term Assets	$2.133B	$2.002B	$1.663B
Total Long-Term Assets	$2.889B	$2.694B	$2.743B
Total Assets	$5.022B	$4.696B	$4.406B
YoY Change	6.96%	4.45%	-1.99%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$636.4M	$571.1M	$477.9M
YoY Change	11.45%	7.67%	-12.93%
Accrued Expenses	$299.5M	$267.2M	$253.9M
YoY Change	12.06%	3.49%	-6.34%
Deferred Revenue	$30.27M	$16.18M
YoY Change	87.11%	-3.34%
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$149.0M	$144.5M	$103.0M
YoY Change	3.13%	26.1%	5.48%
Total Short-Term Liabilities	$1.316B	$1.060B	$992.3M
YoY Change	24.17%	-8.51%	-15.29%
LONG-TERM LIABILITIES
Long-Term Debt	$1.005B	$1.306B	$1.195B
YoY Change	-23.01%	7.23%	-5.76%
Other Long-Term Liabilities	$103.0M	$71.74M	$67.43M
YoY Change	43.57%	-9.27%	23.94%
Total Long-Term Liabilities	$1.108B	$1.377B	$1.262B
YoY Change	-19.54%	6.22%	-4.53%
TOTAL LIABILITIES
Total Short-Term Liabilities	$1.316B	$1.060B	$992.3M
Total Long-Term Liabilities	$1.108B	$1.377B	$1.262B
Total Liabilities	$2.668B	$2.705B	$2.518B
YoY Change	-1.37%	2.49%	-5.81%
SHAREHOLDERS EQUITY
Retained Earnings	$562.5M	$234.1M	$134.9M
YoY Change	140.31%	106.8%	58.94%
Common Stock	$289.0K	$287.0K	$286.0K
YoY Change	0.7%	0.7%	0.35%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$217.7M	$217.5M	$216.3M
YoY Change	0.12%	0.61%	0.08%
Treasury Stock Shares	46.09M shares	46.07M shares	45.98M shares
Shareholders Equity	$2.326B	$1.964B	$1.862B
YoY Change
Total Liabilities & Shareholders Equity	$5.022B	$4.696B	$4.406B
YoY Change	6.96%	4.45%	-1.99%

Cashflow Statement

Concept	2020 Q4	2019 Q4	2019 Q3
OPERATING ACTIVITIES
Net Income	$126.7M	$99.15M	$54.07M
YoY Change	27.76%	250.4%	-4.57%
Depreciation, Depletion And Amortization	$132.7M	$126.2M	$128.8M
YoY Change	5.15%	-11.62%	-10.11%
Cash From Operating Activities	$336.0M	$280.6M	$114.4M
YoY Change	19.74%	18.8%	-48.19%
INVESTING ACTIVITIES
Capital Expenditures	-$277.5M	-$143.9M	-$54.80M
YoY Change	92.84%	108.25%	-38.01%
Acquisitions
YoY Change
Other Investing Activities	$250.1M	$200.0K	-$2.900M
YoY Change	124950.0%	-95.92%	-293.33%
Cash From Investing Activities	-$27.40M	-$143.7M	-$57.80M
YoY Change	-80.93%	124.18%	-33.56%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-180.5M	158.0M	-9.500M
YoY Change	-214.24%	-483.5%	-124.3%
NET CHANGE
Cash From Operating Activities	336.0M	280.6M	114.4M
Cash From Investing Activities	-27.40M	-143.7M	-57.80M
Cash From Financing Activities	-180.5M	158.0M	-9.500M
Net Change In Cash	128.1M	294.9M	47.10M
YoY Change	-56.56%	125.29%	-72.76%
FREE CASH FLOW
Cash From Operating Activities	$336.0M	$280.6M	$114.4M
Capital Expenditures	-$277.5M	-$143.9M	-$54.80M
Free Cash Flow	$613.5M	$424.5M	$169.2M
YoY Change	44.52%	39.04%	-45.28%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0001047127
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2020	dei	Document Annual Report DocumentAnnualReport	true
CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020Q4	us-gaap	Operating Lease Liability Current Statement Of Financial Position Extensible List OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList	us-gaap:AccruedLiabilitiesCurrent
CY2019Q4	us-gaap	Operating Lease Liability Current Statement Of Financial Position Extensible List OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList	us-gaap:AccruedLiabilitiesCurrent
CY2020	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	1	segment
CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Period End Date DocumentPeriodEndDate	2020-12-31
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Entity File Number EntityFileNumber	000-29472
CY2020	dei	Entity Registrant Name EntityRegistrantName	Amkor Technology, Inc.
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	23-1722724
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	2045 East Innovation Circle
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Tempe
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	AZ
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	85284
CY2020	dei	City Area Code CityAreaCode	480
CY2020	dei	Local Phone Number LocalPhoneNumber	821-5000
CY2020	dei	Security12b Title Security12bTitle	Common Stock, $0.001 par value
CY2020	dei	Trading Symbol TradingSymbol	AMKR
CY2020	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2020	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2020	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2020	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2020	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2020	dei	Entity Small Business EntitySmallBusiness	false
CY2020	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2018	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	295239000	USD
CY2020	us-gaap	Research And Development Expense ResearchAndDevelopmentExpense	140727000	USD
CY2020	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2020	dei	Entity Shell Company EntityShellCompany	false
CY2020Q2	dei	Entity Public Float EntityPublicFloat	1222000000	USD
CY2021Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	243341709	shares
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5050589000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4052650000	USD
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CY2020	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	4149775000	USD
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CY2020	us-gaap	Gross Profit GrossProfit	900814000	USD
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CY2018	us-gaap	Gross Profit GrossProfit	710565000	USD
CY2020	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	302842000	USD
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CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	46183000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	37182000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	56250000	USD
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CY2018	us-gaap	Profit Loss ProfitLoss	129565000	USD
CY2020	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	2361000	USD
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CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	239725000	shares
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CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	242248000	shares
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CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	346293000	USD
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CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	128385000	USD
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CY2019Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	267226000	USD
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CY2019Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	91107000	USD
CY2020Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	102996000	USD
CY2019Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	71740000	USD
CY2020Q4	us-gaap	Liabilities Liabilities	2668352000	USD
CY2019Q4	us-gaap	Liabilities Liabilities	2705376000	USD
CY2020Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2019Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2019Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.001
CY2020Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.001
CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2019Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2019Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2019Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.001
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.001
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	288923000	shares
CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	286877000	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	242829000	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	240805000	shares
CY2020Q4	us-gaap	Common Stock Value CommonStockValue	289000	USD
CY2019Q4	us-gaap	Common Stock Value CommonStockValue	287000	USD
CY2020Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1953378000	USD
CY2019Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	1927739000	USD
CY2020Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	562502000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	234077000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	27270000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	19115000	USD
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	46094000	shares
CY2019Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	46072000	shares
CY2020Q4	us-gaap	Treasury Stock Value TreasuryStockValue	217740000	USD
CY2019Q4	us-gaap	Treasury Stock Value TreasuryStockValue	217479000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	2325699000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	1963739000	USD
CY2020Q4	us-gaap	Minority Interest MinorityInterest	28260000	USD
CY2019Q4	us-gaap	Minority Interest MinorityInterest	26500000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2353959000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1990239000	USD
CY2020Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5022311000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	4695615000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1719709000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	129565000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	1293000	USD
CY2018	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	189000	USD
CY2018	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	1050000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	5018000	USD
CY2018	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	546000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1855900000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	122628000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-4697000	USD
CY2019	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	1308000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	11405000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6911000	USD
CY2019	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	600000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	1990239000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	340499000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	8155000	USD
CY2020	us-gaap	Adjustments Related To Tax Withholding For Share Based Compensation AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	261000	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	17611000	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	8030000	USD
CY2020	us-gaap	Dividends Cash DividendsCash	9713000	USD
CY2020	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	601000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2353959000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	340499000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	122628000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	129565000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	510396000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	524177000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	571961000	USD
CY2020	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1979000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1640000	USD
CY2018	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1120000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3143000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	25931000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-13110000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-3042000	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-8536000	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1512000	USD
CY2020	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	2821000	USD
CY2019	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	4477000	USD
CY2018	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-5310000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	8030000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	6911000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	5018000	USD
CY2020	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	779000	USD
CY2019	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-4394000	USD
CY2018	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-2558000	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	106693000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	124140000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-80571000	USD
CY2020	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	75499000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-10208000	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	16310000	USD
CY2020	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	12348000	USD
CY2019	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	2369000	USD
CY2018	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	-4329000	USD
CY2020	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	22614000	USD
CY2019	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	-2253000	USD
CY2018	us-gaap	Increase Decrease In Other Noncurrent Assets IncreaseDecreaseInOtherNoncurrentAssets	-1986000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	48786000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	38670000	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-43490000	USD
CY2020	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	69151000	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-33297000	USD
CY2018	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-78136000	USD
CY2020	us-gaap	Increase Decrease In Pension And Postretirement Obligations IncreaseDecreaseInPensionAndPostretirementObligations	-21535000	USD
CY2019	us-gaap	Increase Decrease In Pension And Postretirement Obligations IncreaseDecreaseInPensionAndPostretirementObligations	-12216000	USD
CY2018	us-gaap	Increase Decrease In Pension And Postretirement Obligations IncreaseDecreaseInPensionAndPostretirementObligations	-4653000	USD
CY2020	amkr	Increase Decreasein Operating Lease Rightofuse Assets Net IncreaseDecreaseinOperatingLeaseRightofuseAssetsNet	-871000	USD
CY2019	amkr	Increase Decreasein Operating Lease Rightofuse Assets Net IncreaseDecreaseinOperatingLeaseRightofuseAssetsNet	127743000	USD
CY2020	amkr	Increase Decreasein Operating Lease Liabilities IncreaseDecreaseinOperatingLeaseLiabilities	2537000	USD
CY2019	amkr	Increase Decreasein Operating Lease Liabilities IncreaseDecreaseinOperatingLeaseLiabilities	131967000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	23888000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-9223000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	15179000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	770033000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	563850000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	663410000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	553021000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	472433000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	547122000	USD
CY2020	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	3819000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	10117000	USD
CY2018	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	2841000	USD
CY2020	us-gaap	Proceeds From Insurance Settlement Investing Activities ProceedsFromInsuranceSettlementInvestingActivities	0	USD
CY2019	us-gaap	Proceeds From Insurance Settlement Investing Activities ProceedsFromInsuranceSettlementInvestingActivities	1538000	USD
CY2018	us-gaap	Proceeds From Insurance Settlement Investing Activities ProceedsFromInsuranceSettlementInvestingActivities	1371000	USD
CY2020	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	535368000	USD
CY2018	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	0	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	159015000	USD
CY2019	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	5935000	USD
CY2018	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	6477000	USD
CY2020	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	247081000	USD
CY2019	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	0	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	6469000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	4829000	USD
CY2020	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	49226000	USD
CY2019	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	13550000	USD
CY2018	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	6754000	USD
CY2020	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	14031000	USD
CY2019	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	15593000	USD
CY2018	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	5864000	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-4574000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	202000	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-6285000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-638705000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-462489000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-537383000	USD
CY2020	us-gaap	Proceeds From Long Term Lines Of Credit ProceedsFromLongTermLinesOfCredit	312000000	USD
CY2019	us-gaap	Proceeds From Long Term Lines Of Credit ProceedsFromLongTermLinesOfCredit	272700000	USD
CY2018	us-gaap	Proceeds From Long Term Lines Of Credit ProceedsFromLongTermLinesOfCredit	0	USD
CY2020	us-gaap	Repayments Of Long Term Lines Of Credit RepaymentsOfLongTermLinesOfCredit	332000000	USD
CY2019	us-gaap	Repayments Of Long Term Lines Of Credit RepaymentsOfLongTermLinesOfCredit	272700000	USD
CY2018	us-gaap	Repayments Of Long Term Lines Of Credit RepaymentsOfLongTermLinesOfCredit	75000000	USD
CY2020	us-gaap	Proceeds From Short Term Debt ProceedsFromShortTermDebt	86769000	USD
CY2019	us-gaap	Proceeds From Short Term Debt ProceedsFromShortTermDebt	51434000	USD
CY2018	us-gaap	Proceeds From Short Term Debt ProceedsFromShortTermDebt	23341000	USD
CY2020	us-gaap	Repayments Of Short Term Debt RepaymentsOfShortTermDebt	87353000	USD
CY2019	us-gaap	Repayments Of Short Term Debt RepaymentsOfShortTermDebt	52635000	USD
CY2018	us-gaap	Repayments Of Short Term Debt RepaymentsOfShortTermDebt	46631000	USD
CY2020	us-gaap	Proceeds From Issuance Of Other Long Term Debt ProceedsFromIssuanceOfOtherLongTermDebt	331033000	USD
CY2019	us-gaap	Proceeds From Issuance Of Other Long Term Debt ProceedsFromIssuanceOfOtherLongTermDebt	975575000	USD
CY2018	us-gaap	Proceeds From Issuance Of Other Long Term Debt ProceedsFromIssuanceOfOtherLongTermDebt	596226000	USD
CY2020	us-gaap	Repayments Of Other Long Term Debt RepaymentsOfOtherLongTermDebt	648514000	USD
CY2019	us-gaap	Repayments Of Other Long Term Debt RepaymentsOfOtherLongTermDebt	862927000	USD
CY2018	us-gaap	Repayments Of Other Long Term Debt RepaymentsOfOtherLongTermDebt	535738000	USD
CY2020	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	1644000	USD
CY2019	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	7027000	USD
CY2018	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	3796000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	9851000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	6574000	USD
CY2018	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	3930000	USD
CY2020	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	17611000	USD
CY2019	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	11405000	USD
CY2018	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	1050000	USD
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1770000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1001000	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	3855000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-333719000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	108250000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-40623000	USD
CY2020	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	6056000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	870000	USD
CY2018	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-204000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-196335000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	210481000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	85200000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	898532000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	688051000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	602851000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	702197000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	898532000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	688051000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	61295000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	65992000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	77575000	USD
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	43404000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	44495000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	63080000	USD
CY2020	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	181376000	USD
CY2019	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	77250000	USD
CY2018	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	256070000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	41672000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	60963000	USD
CY2018	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	0	USD
CY2020	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	10517000	USD
CY2019	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	10835000	USD
CY2018	us-gaap	Capital Lease Obligations Incurred CapitalLeaseObligationsIncurred	17163000	USD
CY2020Q4	us-gaap	Dividends Payable Current DividendsPayableCurrent	9713000	USD
CY2020	us-gaap	Nature Of Operations NatureOfOperations	<div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Description of Business</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Amkor is one of the world’s leading providers of outsourced semiconductor packaging and test services. Amkor pioneered the outsourcing of semiconductor packaging and test services through a predecessor corporation in 1968, and over the years we have built a leading position by:</span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Designing and developing innovative packaging and test technologies;</span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Offering a broad portfolio of cost-effective solutions and services;</span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Focusing on strategic end markets that offer solid growth potential;</span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Cultivating long-standing relationships with our customers, which include many of the world’s leading semiconductor companies; </span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Collaborating with customers, original equipment manufacturers (“OEMs”) and equipment and material suppliers;</span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Developing a competitive cost structure with disciplined capital investment; </span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Building expertise in high-volume manufacturing processes and developing a reputation for high quality and solid execution; and</span></div><div style="margin-top:9pt;padding-left:36pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">•</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%;padding-left:14.5pt">Providing a geographically diverse operating base, with research and development, engineering support and production capabilities at various facilities in China, Japan, Korea, Malaysia, the Philippines, Portugal and Taiwan.</span></div>
CY2020	us-gaap	Use Of Estimates UseOfEstimates	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 acquisitions, revenue recognition, income taxes, inventory, long lived assets and contingencies. 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 Covid-19 and any deterioration in the global business and economic environment. Certain prior year amounts have been reclassified to conform to current year presentation.
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.43
CY2020Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	146800000	USD
CY2019Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	125400000	USD
CY2020Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	51600000	USD
CY2019Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	17500000	USD
CY2020Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	30300000	USD
CY2019Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	16200000	USD
CY2020	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	14100000	USD
CY2019	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	16400000	USD
CY2018	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	13700000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	8000000.0	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	6900000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	5000000.0	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1300000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1300000	USD
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	1000000.0	USD
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	5845000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	9.11
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	805000	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	12.85
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	1882000	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	9.26
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	402000	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	9.56
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	4366000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	9.70
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P7Y5M19D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	23391000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber	4245000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice	9.66
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1	P7Y5M4D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue	22877000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	2197000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	8.92
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P6Y4M28D
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	13407000	USD
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P5Y7M6D
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y
CY2018	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P6Y
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.003
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.025
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.027
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.52
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.42
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.3
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	5.79
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	4.06
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	4.17
CY2020	amkr	Restricted Shares Vesting Percentage RestrictedSharesVestingPercentage	0.0833
CY2020	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	5449000	USD
CY2019	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	6655000	USD
CY2018	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	4133000	USD
CY2020	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-9608000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-1944000	USD
CY2018	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-1451000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-3042000	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-8536000	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-1512000	USD
CY2020	amkr	Other Nonoperating Income Expense Net OtherNonoperatingIncomeExpenseNet	806000	USD
CY2019	amkr	Other Nonoperating Income Expense Net OtherNonoperatingIncomeExpenseNet	2052000	USD
CY2018	amkr	Other Nonoperating Income Expense Net OtherNonoperatingIncomeExpenseNet	5447000	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-6395000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-1773000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	6617000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	38719000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	1138000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	5535000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	347963000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	158672000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	180280000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	386682000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	159810000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	185815000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	4608000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-179000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	22003000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	134000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	3000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	39000	USD
CY2020	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	38298000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	11427000	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	47318000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	43040000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	11251000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	69360000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-7877000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1832000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	5468000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-535000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	299000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	2993000	USD
CY2020	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	11555000	USD
CY2019	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	23800000	USD
CY2018	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-21571000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3143000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	25931000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-13110000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	46183000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	37182000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	56250000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	81203000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	33560000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	39021000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	346000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	293000	USD
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	1677000	USD
CY2020	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	-27988000	USD
CY2019	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	-10600000	USD
CY2018	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	6340000	USD
CY2020	amkr	Income Tax Reconciliation Foreign Exchange Gain Loss IncomeTaxReconciliationForeignExchangeGainLoss	6710000	USD
CY2019	amkr	Income Tax Reconciliation Foreign Exchange Gain Loss IncomeTaxReconciliationForeignExchangeGainLoss	84000	USD
CY2018	amkr	Income Tax Reconciliation Foreign Exchange Gain Loss IncomeTaxReconciliationForeignExchangeGainLoss	-3797000	USD
CY2020	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-15624000	USD
CY2019	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	18374000	USD
CY2018	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-12662000	USD
CY2020	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	-2575000	USD
CY2019	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	-3190000	USD
CY2018	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	1898000	USD
CY2020	amkr	Effective Income Tax Rate Reconciliation Tax Cutsand Jobs Actof2017 Incomplete Accounting Provisional Income Tax Expense Benefit EffectiveIncomeTaxRateReconciliationTaxCutsandJobsActof2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit	0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Unrealized Currency Losses DeferredTaxAssetsUnrealizedCurrencyLosses	5603000	USD
CY2019	amkr	Effective Income Tax Rate Reconciliation Tax Cutsand Jobs Actof2017 Incomplete Accounting Provisional Income Tax Expense Benefit EffectiveIncomeTaxRateReconciliationTaxCutsandJobsActof2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit	0	USD
CY2018	amkr	Effective Income Tax Rate Reconciliation Tax Cutsand Jobs Actof2017 Incomplete Accounting Provisional Income Tax Expense Benefit EffectiveIncomeTaxRateReconciliationTaxCutsandJobsActof2017IncompleteAccountingProvisionalIncomeTaxExpenseBenefit	22284000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	21525000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	9006000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	18106000	USD
CY2020	us-gaap	Income Tax Reconciliation Repatriation Of Foreign Earnings IncomeTaxReconciliationRepatriationOfForeignEarnings	23853000	USD
CY2019	us-gaap	Income Tax Reconciliation Repatriation Of Foreign Earnings IncomeTaxReconciliationRepatriationOfForeignEarnings	3360000	USD
CY2018	us-gaap	Income Tax Reconciliation Repatriation Of Foreign Earnings IncomeTaxReconciliationRepatriationOfForeignEarnings	387000	USD
CY2020	amkr	Effective Income Tax Rate Reconciliation Foreign Derived Intangible Income EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome	6339000	USD
CY2019	amkr	Effective Income Tax Rate Reconciliation Foreign Derived Intangible Income EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome	3195000	USD
CY2018	amkr	Effective Income Tax Rate Reconciliation Foreign Derived Intangible Income EffectiveIncomeTaxRateReconciliationForeignDerivedIntangibleIncome	0	USD
CY2020	amkr	Effective Income Tax Rate Reconciliation Expirationof Net Operating Losses EffectiveIncomeTaxRateReconciliationExpirationofNetOperatingLosses	144000	USD
CY2019	amkr	Effective Income Tax Rate Reconciliation Expirationof Net Operating Losses EffectiveIncomeTaxRateReconciliationExpirationofNetOperatingLosses	3084000	USD
CY2018	amkr	Effective Income Tax Rate Reconciliation Expirationof Net Operating Losses EffectiveIncomeTaxRateReconciliationExpirationofNetOperatingLosses	19462000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	6801000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	3256000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	-1230000	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	1177000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	1162000	USD
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	976000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	46183000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	37182000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	56250000	USD
CY2020	us-gaap	Income Tax Holiday Aggregate Dollar Amount IncomeTaxHolidayAggregateDollarAmount	27600000	USD
CY2019	us-gaap	Income Tax Holiday Aggregate Dollar Amount IncomeTaxHolidayAggregateDollarAmount	14700000	USD
CY2018	us-gaap	Income Tax Holiday Aggregate Dollar Amount IncomeTaxHolidayAggregateDollarAmount	1900000	USD
CY2020	amkr	Income Tax Holiday Tax Benefit Diluted Earnings Per Share IncomeTaxHolidayTaxBenefitDilutedEarningsPerShare	0.11
CY2019	amkr	Income Tax Holiday Tax Benefit Diluted Earnings Per Share IncomeTaxHolidayTaxBenefitDilutedEarningsPerShare	0.06
CY2018	amkr	Income Tax Holiday Tax Benefit Diluted Earnings Per Share IncomeTaxHolidayTaxBenefitDilutedEarningsPerShare	0.01
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	24791000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	25905000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	93056000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards DeferredTaxAssetsTaxCreditCarryforwards	98158000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Unrealized Currency Losses DeferredTaxAssetsUnrealizedCurrencyLosses	2750000	USD
CY2020Q4	amkr	Deferred Tax Assets Operating Lease Liabilities DeferredTaxAssetsOperatingLeaseLiabilities	20343000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	25342000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	27199000	USD
CY2020Q4	amkr	Deferred Tax Assets Tax Deferred Expense Reservesand Accruals Interest Expense DeferredTaxAssetsTaxDeferredExpenseReservesandAccrualsInterestExpense	10306000	USD
CY2019Q4	amkr	Deferred Tax Assets Tax Deferred Expense Reservesand Accruals Interest Expense DeferredTaxAssetsTaxDeferredExpenseReservesandAccrualsInterestExpense	12361000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	57586000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	61812000	USD
CY2020Q4	amkr	Deferred Tax Assets Other Deferred Liabilities DeferredTaxAssetsOtherDeferredLiabilities	33295000	USD
CY2019Q4	amkr	Deferred Tax Assets Other Deferred Liabilities DeferredTaxAssetsOtherDeferredLiabilities	30558000	USD
CY2019Q4	amkr	Deferred Tax Assets Operating Lease Liabilities DeferredTaxAssetsOperatingLeaseLiabilities	18164000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	11741000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	11889000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	282063000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	288796000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	121310000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	136934000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	160753000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	151862000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	28440000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	23747000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Tax Deferred Income DeferredTaxLiabilitiesTaxDeferredIncome	11907000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Tax Deferred Income DeferredTaxLiabilitiesTaxDeferredIncome	11193000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Unrealized Currency Transaction Gains DeferredTaxLiabilitiesUnrealizedCurrencyTransactionGains	5620000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Unrealized Currency Transaction Gains DeferredTaxLiabilitiesUnrealizedCurrencyTransactionGains	1195000	USD
CY2020Q4	amkr	Deferred Tax Liabilities Unbilled Receivables DeferredTaxLiabilitiesUnbilledReceivables	2031000	USD
CY2019Q4	amkr	Deferred Tax Liabilities Unbilled Receivables DeferredTaxLiabilitiesUnbilledReceivables	3580000	USD
CY2020Q4	amkr	Deferred Tax Liabilities Operating Lease Rightofuse Asset DeferredTaxLiabilitiesOperatingLeaseRightofuseAsset	19704000	USD
CY2019Q4	amkr	Deferred Tax Liabilities Operating Lease Rightofuse Asset DeferredTaxLiabilitiesOperatingLeaseRightofuseAsset	17687000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	4514000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	4125000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	72216000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	61527000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	88537000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	90335000	USD
CY2020Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	95045000	USD
CY2019Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	90465000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	6508000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	130000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	88537000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	90335000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	121310000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	136934000	USD
CY2020	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-12400000	USD
CY2020	amkr	Repatriation Of Earnings Estimated Tax Impact RepatriationOfEarningsEstimatedTaxImpact	119100000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	26242000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	25268000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	27211000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	10427000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	8944000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	401000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	1173000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	188000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	636000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	280000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	4539000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	2958000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	1886000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	4964000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	1733000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	22000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	32598000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	26242000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	25268000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Period Increase Decrease UnrecognizedTaxBenefitsPeriodIncreaseDecrease	6400000	USD
CY2020Q4	us-gaap	Decrease In Unrecognized Tax Benefits Is Reasonably Possible DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible	7100000	USD
CY2020Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	28300000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	4700000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	338138000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	120888000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	127092000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	241509000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	239725000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	239329000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	739000	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	397000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	412000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	242248000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	240122000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	239741000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.40
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.50
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.53
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.40
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.50
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.53
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	2412000	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	5379000	shares
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	3662000	shares
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	275801000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	48000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	23000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	275826000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	27100000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	259652000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	259667000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	14705000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	14713000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	1444000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	1446000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	275801000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	275826000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	40856000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	7924859000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	7381922000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	5358857000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	4977072000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	2566002000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	2404850000	USD
CY2020	us-gaap	Depreciation Depreciation	509770000	USD
CY2019	us-gaap	Depreciation Depreciation	522011000	USD
CY2018	us-gaap	Depreciation Depreciation	570304000	USD
CY2018	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	43600000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	52882000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	41559000	USD
CY2020	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	6520000	USD
CY2019	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	5240000	USD
CY2020	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	987000	USD
CY2019	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	933000	USD
CY2020	amkr	Finance Lease Cost FinanceLeaseCost	7507000	USD
CY2019	amkr	Finance Lease Cost FinanceLeaseCost	6173000	USD
CY2020	us-gaap	Short Term Lease Cost ShortTermLeaseCost	7188000	USD
CY2019	us-gaap	Short Term Lease Cost ShortTermLeaseCost	8927000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	5307000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	5416000	USD
CY2020	us-gaap	Lease Cost LeaseCost	72884000	USD
CY2019	us-gaap	Lease Cost LeaseCost	62075000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	53323000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	39870000	USD
CY2020	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	946000	USD
CY2019	us-gaap	Finance Lease Interest Payment On Liability FinanceLeaseInterestPaymentOnLiability	893000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	9851000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	6574000	USD
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P3Y10M24D
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P4Y8M12D
CY2020Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P3Y1M6D
CY2019Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P3Y7M6D
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.040
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.042
CY2020Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.040
CY2019Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.046
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	55196000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	13409000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	36850000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	6395000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	19974000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	3777000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	10213000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	1063000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	7925000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	997000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	17255000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	2046000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	147413000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	27687000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	13245000	USD
CY2020Q4	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	1997000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	134168000	USD
CY2020Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	25690000	USD
CY2020Q4	amkr	Lessee Lease Not Yet Commenced Liability LesseeLeaseNotYetCommencedLiability	8000000	USD
CY2020Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	143383000	USD
CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	115693000	USD
CY2020Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	49748000	USD
CY2019Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	40972000	USD
CY2020Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	30269000	USD
CY2019Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	16177000	USD
CY2020Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	26602000	USD
CY2019Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	11661000	USD
CY2020Q4	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	12634000	USD
CY2019Q4	us-gaap	Finance Lease Liability Current FinanceLeaseLiabilityCurrent	9121000	USD
CY2020Q4	us-gaap	Supplemental Unemployment Benefits Severance Benefits SupplementalUnemploymentBenefitsSeveranceBenefits	10837000	USD
CY2019Q4	us-gaap	Supplemental Unemployment Benefits Severance Benefits SupplementalUnemploymentBenefitsSeveranceBenefits	13408000	USD
CY2020Q4	us-gaap	Interest Payable Current InterestPayableCurrent	10767000	USD
CY2019Q4	us-gaap	Interest Payable Current InterestPayableCurrent	11638000	USD
CY2020Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	64967000	USD
CY2019Q4	us-gaap	Other Accrued Liabilities Current OtherAccruedLiabilitiesCurrent	48556000	USD
CY2020Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	349207000	USD
CY2019Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	267226000	USD
CY2020Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1164302000	USD
CY2019Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1460351000	USD
CY2020Q4	us-gaap	Debt Instrument Unamortized Discount Premium And Debt Issuance Costs Net DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet	-9956000	USD
CY2019Q4	us-gaap	Debt Instrument Unamortized Discount Premium And Debt Issuance Costs Net DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet	-10117000	USD
CY2020Q4	us-gaap	Debt Current DebtCurrent	149007000	USD
CY2019Q4	us-gaap	Debt Current DebtCurrent	144479000	USD
CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1005339000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1305755000	USD
CY2020Q4	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	105000000.0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	149007000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	182373000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	170776000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	81461000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	27400000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	553285000	USD
CY2020Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	1164302000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	207448000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	175712000	USD
CY2020	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	29848000	USD
CY2019	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	31355000	USD
CY2020	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	4980000	USD
CY2019	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	5244000	USD
CY2020	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	8380000	USD
CY2019	us-gaap	Defined Benefit Plan Benefit Obligation Benefits Paid DefinedBenefitPlanBenefitObligationBenefitsPaid	11742000	USD
CY2020	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	6104000	USD
CY2019	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	12540000	USD
CY2020	us-gaap	Defined Benefit Plan Accumulated Benefit Obligation Increase Decrease For Settlement And Curtailment DefinedBenefitPlanAccumulatedBenefitObligationIncreaseDecreaseForSettlementAndCurtailment	-2410000	USD
CY2019	us-gaap	Defined Benefit Plan Accumulated Benefit Obligation Increase Decrease For Settlement And Curtailment DefinedBenefitPlanAccumulatedBenefitObligationIncreaseDecreaseForSettlementAndCurtailment	0	USD
CY2020	us-gaap	Defined Benefit Plan Settlements Benefit Obligation DefinedBenefitPlanSettlementsBenefitObligation	31804000	USD
CY2019	us-gaap	Defined Benefit Plan Settlements Benefit Obligation DefinedBenefitPlanSettlementsBenefitObligation	5310000	USD
CY2020	us-gaap	Defined Benefit Plan Foreign Currency Exchange Rate Changes Benefit Obligation DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation	-16723000	USD
CY2019	us-gaap	Defined Benefit Plan Foreign Currency Exchange Rate Changes Benefit Obligation DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation	351000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	222509000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Benefit Obligation DefinedBenefitPlanBenefitObligation	207448000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	145158000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	123370000	USD
CY2020	us-gaap	Defined Benefit Plan Actual Return On Plan Assets DefinedBenefitPlanActualReturnOnPlanAssets	11400000	USD
CY2019	us-gaap	Defined Benefit Plan Actual Return On Plan Assets DefinedBenefitPlanActualReturnOnPlanAssets	12221000	USD
CY2020	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	25080000	USD
CY2019	us-gaap	Defined Benefit Plan Contributions By Employer DefinedBenefitPlanContributionsByEmployer	27134000	USD
CY2020	us-gaap	Defined Benefit Plan Settlements Plan Assets DefinedBenefitPlanSettlementsPlanAssets	31804000	USD
CY2019	us-gaap	Defined Benefit Plan Settlements Plan Assets DefinedBenefitPlanSettlementsPlanAssets	5310000	USD
CY2020	us-gaap	Defined Benefit Plan Plan Assets Benefits Paid DefinedBenefitPlanPlanAssetsBenefitsPaid	8380000	USD
CY2019	us-gaap	Defined Benefit Plan Plan Assets Benefits Paid DefinedBenefitPlanPlanAssetsBenefitsPaid	11742000	USD
CY2020	us-gaap	Defined Benefit Plan Plan Assets Foreign Currency Translation Gain Loss DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss	13757000	USD
CY2019	us-gaap	Defined Benefit Plan Plan Assets Foreign Currency Translation Gain Loss DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss	-515000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	155211000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	145158000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Funded Status Of Plan DefinedBenefitPlanFundedStatusOfPlan	-67298000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Funded Status Of Plan DefinedBenefitPlanFundedStatusOfPlan	-62290000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	4856000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	498000	USD
CY2020Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Current And Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent	72154000	USD
CY2019Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Current And Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent	62788000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-67298000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Amounts Recognized In Balance Sheet DefinedBenefitPlanAmountsRecognizedInBalanceSheet	-62290000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Accumulated Benefit Obligation DefinedBenefitPlanAccumulatedBenefitObligation	164700000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Benefit Obligation DefinedBenefitPlanAccumulatedBenefitObligation	154700000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Pension Plan With Projected Benefit Obligation In Excess Of Plan Assets Projected Benefit Obligation DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation	140424000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Pension Plan With Projected Benefit Obligation In Excess Of Plan Assets Projected Benefit Obligation DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation	197377000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Pension Plan With Projected Benefit Obligation In Excess Of Plan Assets Plan Assets DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssets	68270000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Pension Plan With Projected Benefit Obligation In Excess Of Plan Assets Plan Assets DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssets	134589000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Accumulated Benefit Obligation DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation	76426000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Accumulated Benefit Obligation DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation	71059000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Fair Value Of Plan Assets DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets	25292000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Fair Value Of Plan Assets DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets	24043000	USD
CY2020	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	29848000	USD
CY2019	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	31355000	USD
CY2018	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	32913000	USD
CY2020	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	4980000	USD
CY2019	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	5244000	USD
CY2018	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	4867000	USD
CY2020	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	5506000	USD
CY2019	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	6412000	USD
CY2018	us-gaap	Defined Benefit Plan Expected Return On Plan Assets DefinedBenefitPlanExpectedReturnOnPlanAssets	5640000	USD
CY2020	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	0	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	0	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Prior Service Cost Credit DefinedBenefitPlanAmortizationOfPriorServiceCostCredit	6000	USD
CY2020	us-gaap	Defined Benefit Plan Actuarial Gain Loss Immediate Recognition As Component In Net Periodic Benefit Cost Credit DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit	-56000	USD
CY2019	us-gaap	Defined Benefit Plan Actuarial Gain Loss Immediate Recognition As Component In Net Periodic Benefit Cost Credit DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit	374000	USD
CY2018	us-gaap	Defined Benefit Plan Actuarial Gain Loss Immediate Recognition As Component In Net Periodic Benefit Cost Credit DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit	147000	USD
CY2020	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	29378000	USD
CY2019	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	29813000	USD
CY2018	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	31999000	USD
CY2020	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Settlements1 DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1	-62000	USD
CY2019	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Settlements1 DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1	210000	USD
CY2018	us-gaap	Defined Benefit Plan Recognized Net Gain Loss Due To Settlements1 DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1	1639000	USD
CY2020	us-gaap	Pension Expense PensionExpense	29440000	USD
CY2019	us-gaap	Pension Expense PensionExpense	29603000	USD
CY2018	us-gaap	Pension Expense PensionExpense	30360000	USD
CY2020	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate	0.025
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate	0.031
CY2018	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate	0.032
CY2020Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.023
CY2019Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.025
CY2018Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Discount Rate DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate	0.031
CY2020	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease	0.037
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease	0.036
CY2018	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease	0.038
CY2020Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease	0.037
CY2019Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease	0.037
CY2018Q4	us-gaap	Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease	0.036
CY2020	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.038
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.051
CY2018	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.049
CY2020Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	155211000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	145158000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Employer Contributions Next Fiscal Year DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear	23000000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths	13482000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Two DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo	11299000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Three DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree	13528000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Four DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour	14894000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Five DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive	18252000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter	125576000	USD
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	16500000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	13600000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	12200000	USD
CY2020Q4	us-gaap	Dividends Payable Date Of Record Day Month And Year DividendsPayableDateOfRecordDayMonthAndYear	2020-12-18
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-4697000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-4108000	USD
CY2019	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	589000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	7943000	USD
CY2020	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-212000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	8155000	USD
CY2020	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	35900000	USD
CY2019	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	100000	USD
CY2018	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	2500000	USD
CY2020Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1371041000	USD
CY2020Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1354023000	USD
CY2020Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1172909000	USD
CY2020Q4	us-gaap	Purchase Obligation PurchaseObligation	11000000.0	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5050589000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4052650000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4316466000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	5050589000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4052650000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4316466000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	2566002000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	2404850000	USD
CY2019Q4	us-gaap	Restructuring Reserve RestructuringReserve	2641000	USD
CY2020	us-gaap	Restructuring Charges RestructuringCharges	18006000	USD
CY2020	us-gaap	Payments For Restructuring PaymentsForRestructuring	14323000	USD
CY2020	us-gaap	Restructuring Reserve Translation And Other Adjustment RestructuringReserveTranslationAndOtherAdjustment	19000	USD
CY2020Q4	us-gaap	Restructuring Reserve RestructuringReserve	6343000	USD
CY2020Q4	us-gaap	Restructuring And Related Cost Cost Incurred To Date1 RestructuringAndRelatedCostCostIncurredToDate1	25960000	USD
CY2020Q4	us-gaap	Restructuring And Related Cost Expected Cost Remaining1 RestructuringAndRelatedCostExpectedCostRemaining1	4066000	USD
CY2020Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1152616000	USD
CY2019Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1178464000	USD
CY2019Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1083917000	USD
CY2019Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	895305000	USD
CY2019Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	894964000	USD
CY2020Q4	us-gaap	Gross Profit GrossProfit	278501000	USD
CY2020Q3	us-gaap	Gross Profit GrossProfit	241085000	USD
CY2020Q2	us-gaap	Gross Profit GrossProfit	192320000	USD
CY2020Q1	us-gaap	Gross Profit GrossProfit	188908000	USD
CY2019Q4	us-gaap	Gross Profit GrossProfit	222984000	USD
CY2019Q3	us-gaap	Gross Profit GrossProfit	182240000	USD
CY2019Q2	us-gaap	Gross Profit GrossProfit	123454000	USD
CY2019Q1	us-gaap	Gross Profit GrossProfit	120761000	USD
CY2020Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	159179000	USD
CY2020Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	127469000	USD
CY2020Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	86524000	USD
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.04
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.10
CY2020Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	84073000	USD
CY2019Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	118385000	USD
CY2019Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	78855000	USD
CY2019Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	22510000	USD
CY2019Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	13420000	USD
CY2020Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12679000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	15753000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	12905000	USD
CY2020Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	4846000	USD
CY2019Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	764000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9141000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	5897000	USD
CY2019Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	21380000	USD
CY2020Q4	us-gaap	Profit Loss ProfitLoss	126965000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	92897000	USD
CY2020Q2	us-gaap	Profit Loss ProfitLoss	56140000	USD
CY2020Q1	us-gaap	Profit Loss ProfitLoss	64497000	USD
CY2019Q4	us-gaap	Profit Loss ProfitLoss	99816000	USD
CY2019Q2	us-gaap	Profit Loss ProfitLoss	-9006000	USD
CY2019Q1	us-gaap	Profit Loss ProfitLoss	-22668000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	126674000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	54486000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	92151000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	55424000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	63889000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	99147000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	54070000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	-9450000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	-22879000	USD
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.52
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.38
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.23
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.27
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.41
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.23
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.52
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.38
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.23
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.26
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.41
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.23
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.04
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.10
CY2020Q4	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-20200000	USD
CY2019Q4	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-3800000	USD
CY2019Q1	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	14900000	USD

Files In Submission

Name	View Source	Status
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$AMKR
AMKOR TECHNOLOGY, INC. Stock $amkr

2020 Q4 Form 10-K Financial Statement

#000104712721000010 Filed on February 19, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$AMKR AMKOR TECHNOLOGY, INC. Stock $amkr

2020 Q4 Form 10-K Financial Statement

#000104712721000010 Filed on February 19, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$AMKR
AMKOR TECHNOLOGY, INC. Stock $amkr