Document Type Document Type 6.625% Senior notes, due September 2027 Senior Notes Due September 2027 [Member] Senior Notes Due September 2027 [Member] Other (income) expense, net Other (income) expense, net Other Nonoperating Income (Expense) Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Treasury Stock Treasury Stock [Member] Payables and Accruals [Abstract] Payables and Accruals [Abstract] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Pension Plans Retirement Benefits [Text Block] Changes in accumulated other comprehensive income (loss), net of tax Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] China CHINA Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Other current assets Other Current Assets [Member] Fair value Derivative Asset After 1 year through 5 years, Fair Value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Statistical Measurement [Domain] Statistical Measurement [Domain] LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Line of Credit Line of Credit [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Subsidiary dividends to non-controlling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Term loan, fixed rate at 1.35%, due December 2024 Term Loan, Fixed Rate at 1.35% Due December 2024 [Member] Term Loan, Fixed Rate at 1.35% Due December 2024 [Member] Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Security Exchange Name Security Exchange Name Unused borrowing capacity Debt Instrument, Unused Borrowing Capacity, Amount Finance lease assets Finance Lease, Right-of-Use Asset, before Accumulated Amortization Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Operating income Operating Income (Loss) Total current liabilities Liabilities, Current Defined Contribution Plan Disclosure [Line Items] Defined Contribution Plan Disclosure [Line Items] Variable Rate [Domain] Variable Rate [Domain] Variable Rate [Axis] Variable Rate [Axis] Commitments and contingencies (Note 15) Commitments and Contingencies Treasury stock acquired through surrender of shares for tax withholding Share-based Payment Arrangement, Decrease for Tax Withholding Obligation ASSETS Assets [Abstract] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Furniture, fixtures and other equipment Furniture and Fixtures [Member] Issuance of stock through share-based compensation plans Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Entity Address, State or Province Entity Address, State or Province Trade accounts payable Accounts Payable, Current Accrued Expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Retained earnings Retained Earnings (Accumulated Deficit) Operating lease right of use assets Operating Lease, Right-of-Use Asset Term loan, LIBOR plus 1.60%, due March 2022 Term Loan, LIBOR plus 1.60% Due March 2022 [Member] Term Loan, LIBOR plus 1.60% Due March 2022 [Member] Loss on debt retirement Gain (Loss) on Extinguishment of Debt Automotive, industrial and other (driver assist, infotainment, performance, safety) Sales Channel, Automotive, Industrial And Other [Member] Sales Channel, Automotive, Industrial And Other [Member] $250 million senior secured revolving credit facility, LIBOR plus 1.25%-1.75%, due July 2023 (Singapore) Senior Secured Revolving Credit Facility due July 2023 [Member] Senior Secured Revolving Credit Facility due July 2023 [Member] Term loan, fixed rate at 0.60%, due July 2022 Term Loan, Fixed Rate at 0.60% Due July 2022 [Member] Term Loan, Fixed Rate at 0.60% Due July 2022 [Member] Preferred stock, $0.001 par value, 10,000 shares authorized, designated Series A, none issued Preferred Stock, Value, Issued Income Taxes Income Tax, Policy [Policy Text Block] Revolving credit facilities and term loans Subsidiary Term Loan and Revolving Credit Facility [Member] Subsidiary Term Loans and Revolving Credit Facilities [Member] Total operating expenses Operating Expenses Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Other non-current liabilities Other Liabilities, Noncurrent Other investing activities Payments for (Proceeds from) Other Investing Activities Payments of finance lease obligations Finance Lease, Principal Payments AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Share-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Effect of exchange rate fluctuations on cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Unbilled receivables Unbilled Receivables, Current Inventories Inventory, Net Net sales by product group Revenue from Contract with Customer, Excluding Assessed Tax Share-based awards Stock Options And Restricted Shares [Member] Stock options and restricted shares. Total net sales Concentration Risk, Percentage Geographical [Domain] Geographical [Domain] After 5 years through 10 years, Fair Value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Statement [Line Items] Statement [Line Items] Capital expenditures payable Capital expenditures payable Amount owed for capital expenditures. Summary of potential shares of common stock excluded from diluted earnings per share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Weighted average interest rate (as a percent) Long-term Debt, Weighted Average Interest Rate, at Point in Time Net income attributable to Amkor per common share: Earnings Per Share, Basic and Diluted [Abstract] Renewal term Debt Instrument, Term Proceeds from revolving credit facilities Proceeds from Long-term Lines of Credit Accrued interest Interest Payable, Current Statement [Table] Statement [Table] Type of Restructuring [Domain] Type of Restructuring [Domain] Interest cost Defined Benefit Plan, Interest Cost Statistical Measurement [Axis] Statistical Measurement [Axis] Credit Facility [Axis] Credit Facility [Axis] Advanced products Advanced Products [Member] Advanced Products [Member] Total debt Debt Instrument, Fair Value Disclosure After 10 Years, Fair Value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Preferred stock designated Series A, shares issued Preferred Stock, Shares Issued Payments of revolving credit facilities Repayments of Long-term Lines of Credit Payment term Line of Credit Facility, Payment Term Line of Credit Facility, Payment Term U.S. government agency bonds US Government Agencies Debt Securities [Member] Weighted Average Weighted Average [Member] Restructuring and Related Activities [Abstract] Restructuring and Related Activities [Abstract] Communications (handheld devices, smartphones, tablets) Sales Channel, Communications [Member] Sales Channel, Communications [Member] Entity Small Business Entity Small Business Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Debt Debt Disclosure [Text Block] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Term loan, fixed rate at 0.86%, due June 2022 Term Loan Due June 2022 [Member] Term Loan Due June 2022 [Member] Other Other Nonoperating Income (Expense), Net The net of miscellaneous income and expense items that are combined together as a component of Other Nonoperating Income (Expense). Amendment Flag Amendment Flag Factoring of Accounts Receivable [Axis] Factoring of Accounts Receivable [Axis] Factoring of Accounts Receivable [Axis] Computation of basic and diluted earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Shares used in computing per common share amounts: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Other accrued expenses Other Accrued Liabilities, Current Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Entity Central Index Key Entity Central Index Key Restructuring and Other Exit Activities Restructuring and Related Activities Disclosure [Text Block] Derivative Instrument [Axis] Derivative Instrument [Axis] Fair value of financial instruments that are not recorded at fair value on recurring basis Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Financial Instruments [Domain] Financial Instruments [Domain] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Net gain (loss) on derivatives Derivative, Gain (Loss) on Derivative, Net Fair Value Measurement [Domain] Fair Value Measurement [Domain] Proceeds from issuance of long-term debt Proceeds from Issuance of Other Long-term Debt Proceeds from short-term debt Proceeds from Short-term Debt Senior Notes Senior notes Senior Notes [Member] Property, plant and equipment included in capital expenditures payable Capital Expenditures Incurred but Not yet Paid Contract with Customer, Sales Channel [Domain] Contract with Customer, Sales Channel [Domain] Geographical [Axis] Geographical [Axis] Amortized Cost Debt Securities, Available-for-sale, Amortized Cost TIBOR Tokyo Interbank Offered Rate (TIBOR) [Member] Tokyo Interbank Offered Rate (TIBOR) [Member] Gross Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Factoring of Accounts Receivable [Table] Factoring of Accounts Receivable [Table] Factoring of Accounts Receivable [Table] Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Selling, general and administrative Selling, General and Administrative Expense Korea KOREA, REPUBLIC OF Other assets Other Assets, Noncurrent Total assets Assets Interest income Interest Income, Deposits with Financial Institutions Revenue from Contract with Customer Revenue from Contract with Customer Benchmark [Member] Title of 12(b) Security Title of 12(b) Security Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Axis] Summary of accrued expenses Schedule of Accrued Liabilities [Table Text Block] Income taxes payable Accrued Income Taxes, Current Subsequent Event Type [Axis] Subsequent Event Type [Axis] Korean Won Korea (South), Won Antidilutive Securities Excluded from Computation of Earnings Per Share, by Antidilutive Securities [Axis] Antidilutive Securities [Axis] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Japanese Yen Japan, Yen Interest expense Interest Expense Depreciation and amortization Depreciation, Depletion and Amortization Short-term Investments Short-term Investments [Member] Product and Service [Axis] Product and Service [Axis] Total liabilities Liabilities Other Exit Costs Other Restructuring [Member] Term Loan, Fixed Rate at 1.20% Due December 2025 Term Loan, Fixed Rate at 1.20% Due December 2025 [Member] Term Loan, Fixed Rate at 1.20% Due December 2025 Revenue recognized Contract with Customer, Liability, Revenue Recognized Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Net income attributable to Amkor common stockholders Net Income (Loss) Available to Common Stockholders, Basic Level 1 Fair Value, Inputs, Level 1 [Member] Defined Benefit Pension Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Restricted cash Restricted Cash and Cash Equivalents, Noncurrent Debt Instrument [Axis] Debt Instrument [Axis] Additional Paid- In Capital Additional Paid-in Capital [Member] Schedule of other income and expense Schedule of Other Nonoperating Income (Expense) [Table Text Block] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Japan JAPAN Changes in assets and liabilities Increase (Decrease) in Operating Capital Accrued expenses Accounts Payable and Accrued Liabilities [Member] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Adjustments to net unrealized gains (losses) on available-for-sale debt investments Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Machinery and equipment Machinery and Equipment [Member] Common stock, shares outstanding Common Stock, Shares, Outstanding Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Factoring of Accounts Receivable [Abstract] Factoring of Accounts Receivable [Abstract] Factoring of Accounts Receivable [Abstract] Revolving Credit Facility Revolving Credit Facility [Member] Mainstream products Mainstream Products [Member] Mainstream Products [Member] Income before taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Research and development Research and Development Expense Cash equivalents Cash Equivalents [Member] Subsequent Event Subsequent Event [Member] Reclassifications Reclassification, Comparability Adjustment [Policy Text Block] Japan Consolidation Activities Japan Consolidation Activities [Member] Japan Consolidation Activities [Member] Common stock, shares authorized Common Stock, Shares Authorized Concentration Risk Type [Axis] Concentration Risk Type [Axis] Property, plant and equipment Property, Plant and Equipment, Gross Share-based awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Restructuring Plan [Domain] Restructuring Plan [Domain] Subsidiary Term Loans Subsidiary Term Loans [Member] Subsidiary Term Loans [Member] Amount of leases not yet commenced Lessee, Lease Not Yet Commenced, Liability Lessee, Lease Not Yet Commenced, Liability Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Fair Value Estimate of Fair Value Measurement [Member] Income Statement [Abstract] Income Statement [Abstract] Accumulated Other Comprehensive Income (Loss) Total AOCI Attributable to Parent [Member] Pension and severance obligations Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent Long-term operating lease liabilities Operating Lease, Liability, Noncurrent Term Loan Two, LIBOR plus 1.10% Due March 2024 Term Loan Two, LIBOR plus 1.10% Due March 2024 [Member] Term Loan Two, LIBOR plus 1.10% Due March 2024 Adjustments to unrealized components of defined benefit pension plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Less: Unamortized discount and deferred debt costs, net Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Use of Estimates Use of Estimates, Policy [Policy Text Block] Current assets: Assets, Current [Abstract] Comprehensive income attributable to Amkor Comprehensive Income (Loss), Net of Tax, Attributable to Parent Payments for foreign exchange forward contracts Payments for Derivative Instrument, Investing Activities Preferred stock designated Series A, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Proceeds from foreign exchange forward contracts Proceeds from Derivative Instrument, Investing Activities Payments for property, plant and equipment Payments to Acquire Property, Plant, and Equipment City Area Code City Area Code Document Period End Date Document Period End Date Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net sales by product group and end market Disaggregation of Revenue [Table Text Block] Amounts reclassified from accumulated other comprehensive income (loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Other financing activities Proceeds from (Payments for) Other Financing Activities Cover [Abstract] Cover [Abstract] Summary of debt securities available-for-sale Debt Securities, Available-for-sale [Table Text Block] Other comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Debt and Equity Securities, FV-NI [Line Items] Debt and Equity Securities, FV-NI [Line Items] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Long-term Debt Long-term Debt Contract with Customer, Sales Channel [Axis] Contract with Customer, Sales Channel [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Service cost Defined Benefit Plan, Service Cost Other Income and Expense Other Income and Other Expense Disclosure [Text Block] Taiwan TAIWAN, PROVINCE OF CHINA Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Cost of sales Cost of Goods and Services Sold Total Fair Value Debt Securities, Available-for-sale Statement, Equity Components [Axis] Equity Components [Axis] Equity Components [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Minimum Minimum [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Total property, plant and equipment, net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Land Land [Member] Short-term operating lease liabilities Operating Lease, Liability, Current Term Loan One, LIBOR plus 1.10% Due March 2024 Term Loan One, LIBOR plus 1.10% Due March 2024 [Member] Term Loan One, LIBOR plus 1.10% Due March 2024 Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Net income attributable to non-controlling interests Comprehensive income attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Asset-backed securities Asset-backed Securities [Member] Entity Interactive Data Current Entity Interactive Data Current Fair value of derivative instruments in statement of financial position Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Net periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Corporate bonds Corporate Bond Securities [Member] Fair Value Measurements Fair Value Disclosures [Text Block] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Accumulated Other Comprehensive Income (Loss) Stockholders' Equity Note Disclosure [Text Block] Proceeds from maturities of short-term investments Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Fair market value of held-to-maturity securities Debt Securities, Held-to-maturity, Fair Value Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Summary of defined contribution expense Defined Contribution Plan Disclosures [Table Text Block] Entity Registrant Name Entity Registrant Name Subsequent Event Type [Domain] Subsequent Event Type [Domain] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Variable rate demand notes Variable Rate Demand Obligation [Member] Proceeds from sale of property, plant and equipment Proceeds from Sale of Property, Plant, and Equipment Term Loan, LIBOR plus 1.40% due March 2022 Term Loan, LIBOR plus 1.40% Due March 2022 [Member] Term Loan, LIBOR plus 1.40% Due March 2022 [Member] Within 1 year, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Payments of dividends Payments of Ordinary Dividends, Common Stock Effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Term Loan Due April 2024 Term Loan, fixed rate at 1.85%, Due April 2024 [Member] Term Loan, fixed rate at 1.85%, Due April 2024 Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Accounts receivable, net of allowances Accounts Receivable, after Allowance for Credit Loss, Current Foreign Plan [Member] Foreign Plan [Member] Accrual beginning balance Accrual ending balance Restructuring Reserve Gross Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Computing (data center, infrastructure, PC/laptop, storage) Sales Channel, Computing [Member] Sales Channel, Computing [Member] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restructuring Type [Axis] Restructuring Type [Axis] Cash Payments Payments for Restructuring Goodwill Goodwill Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Within 1 year, Fair Value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Document Transition Report Document Transition Report Cash dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Restricted cash Restricted Cash and Cash Equivalents, Current Face amount of debt Debt Instrument, Face Amount Singapore SINGAPORE After 5 years through 10 Years, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Level 2 Level 2 Fair Value, Inputs, Level 2 [Member] Buildings and improvements Building and Building Improvements [Member] Other current assets Other Assets, Current Document Quarterly Report Document Quarterly Report Equity [Abstract] Equity [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Notional Value Derivative Asset, Notional Amount Accrued severance plan obligations Postemployment Benefits Liability, Current Deferred revenue and customer advances Contract with Customer, Liability, Current Payments of short-term debt Repayments of Short-term Debt Credit Facility [Domain] Credit Facility [Domain] Derivative Contract [Domain] Derivative Contract [Domain] Diluted (in shares) Weighted-average number of common shares outstanding - diluted Weighted Average Number of Shares Outstanding, Diluted Defined Contribution Plan [Table] Defined Contribution Plan [Table] Basic (in dollars per share) Earnings Per Share, Basic Non-cash Amounts Restructuring Reserve, Translation and Other Adjustment Other Income and Expenses [Abstract] Other Income and Expenses [Abstract] Estimated additional charges to be incurred Restructuring and Related Cost, Expected Cost Remaining Entity File Number Entity File Number Debt Disclosure [Abstract] Debt Disclosure [Abstract] Term Loan, LIBOR plus 1.10% Due March 2024 Term Loan, LIBOR plus 1.10% Due March 2024 [Member] Term Loan, LIBOR plus 1.10% Due March 2024 Restructuring Plan [Axis] Restructuring Plan [Axis] Payments of long-term debt Repayments of Long-term Debt Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Term loan, applicable bank rate plus 1.77%, due April 2023 Term Loan Due April 2023 [Member] Term Loan Due April 2023 Unrealized Gains (Losses) on Available-for-Sale Debt Investments AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Gross unrecognized tax benefits Unrecognized Tax Benefits Common stock, $0.001 par value, 500,000 shares authorized; 290,341 and 288,923 shares issued; and 244,190 and 242,829 shares outstanding in 2021 and 2020, respectively Common Stock, Value, Issued Document Fiscal Year Focus Document Fiscal Year Focus Commercial paper Commercial Paper [Member] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Less: Short-term borrowings and current portion of long-term debt Long-term Debt, Current Maturities Entity Current Reporting Status Entity Current Reporting Status Software and computer equipment Software and Computer Equipment [Member] Software and Computer Equipment [Member] Short-term borrowings and current portion of long-term debt Debt, Current All Currencies [Domain] All Currencies [Domain] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Issuance of stock through share-based compensation plans, shares Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Non-controlling interests in subsidiaries Stockholders' Equity Attributable to Noncontrolling Interest Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Common stock, shares issued Balance at beginning of period, shares Balance at end of period, shares Common Stock, Shares, Issued Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Foreign Exchange Forward Foreign Exchange Forward [Member] Long-term debt Long-term debt Long-term Debt, Excluding Current Maturities End Market Distribution Channel Concentration Risk [Member] Distribution Channel Concentration Risk [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Total Amkor stockholders’ equity Stockholders' Equity Attributable to Parent Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Discounts and Fees Factoring Fees [Member] Factoring Fees [Member] Total liabilities and equity Liabilities and Equity Payments of long-term debt Repayments of Other Long-term Debt Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] Entity Address, City or Town Entity Address, City or Town Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Payroll and benefits Employee-related Liabilities, Current Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Total Amkor Stockholders’ Equity Parent [Member] Financial Instrument [Axis] Financial Instrument [Axis] Share-based awards Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Other operating activities and non-cash items Other Noncash Income (Expense) Equity Component [Domain] Equity Component [Domain] Applicable Bank Rate Applicable Bank Rate [Member] Applicable Bank Rate [Member] Gross profit Gross Profit Property, plant and equipment, net Property, Plant and Equipment, Net Construction in progress Construction in Progress [Member] Entity Tax Identification Number Entity Tax Identification Number Net income attributable to Amkor Net Income (Loss) Attributable to Parent LIBOR London Interbank Offered Rate (LIBOR) [Member] Total other comprehensive income (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Debt Securities, Trading, and Equity Securities, FV-NI [Table] Debt Securities, Trading, and Equity Securities, FV-NI [Table] After 10 Years, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 After 1 year through 5 years, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Total current assets Assets, Current Current Fiscal Year End Date Current Fiscal Year End Date Retirement Plan Sponsor Location [Domain] Retirement Plan Sponsor Location [Domain] Net income attributable to Amkor per common share: Earnings Per Share [Abstract] Earnings Per Share [Abstract] Charges Restructuring Charges Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Total property, plant and equipment Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization Conversion of severance plan obligation to defined contribution liability Conversion of severance plan obligation to defined contribution liability Conversion of severance plan obligation to defined contribution liability Amortized cost of held-to-maturity securities Debt Securities, Held-to-maturity Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Total Factored Total Factored [Member] Total Accounts Receivable Factored [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Document Fiscal Period Focus Document Fiscal Period Focus Accumulated depreciation and amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Total Cash and Cash Equivalents and Debt Securities, Available-for-sale, Fair Value Disclosure Cash and Cash Equivalents and Debt Securities, Available-for-sale, Fair Value Disclosure Certificate of deposits Certificates of Deposit [Member] Consumer (connected home, set-top boxes, televisions, visual imaging, wearables) Sales Channel, Consumer Goods [Member] Sales Channel, Consumer Goods[Member] Total cumulative charges incurred to date Restructuring and Related Cost, Cost Incurred to Date Entity Filer Category Entity Filer Category Common Stock Common Stock [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Product and Service [Domain] Product and Service [Domain] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Periodic principal payment Debt Instrument, Periodic Payment, Principal Cash dividends declared Dividends, Cash Defined contribution expense Defined Contribution Plan, Cost Summary of property, plant and equipment and depreciation expense Property, Plant and Equipment [Table Text Block] U.S. government bonds US Treasury Securities [Member] Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Stated interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Revolving credit facility, TAIFX plus the applicable bank rate, due December 2024 (Taiwan) Revolving Credit Facility due December 2024 [Member] Revolving Credit Facility due December 2024 [Member] Term loan, fixed rate at 1.30%, due July 2023 Term Loan, Fixed Rate at 1.30% Due July 2023 [Member] Term Loan, Fixed Rate at 1.30% Due July 2023 [Member] Municipal bonds Municipal Bonds [Member] Money market funds Money Market Funds [Member] Factoring of Accounts Receivable [Domain] Factoring of Accounts Receivable [Domain] [Domain] for Factoring of Accounts Receivable [Axis] Non-cash investing and financing activities: Noncash Investing and Financing Items [Abstract] Currency [Axis] Currency [Axis] Net decrease in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Total other expense, net Nonoperating Income (Expense) Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Short term investments amortized cost Debt Securities, Available-for-sale, Amortized Cost, Current Foreign Currency Translation Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Basic (in shares) Weighted-average number of common shares outstanding - basic Weighted Average Number of Shares Outstanding, Basic Basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Treasury stock, shares Balance at beginning of period, shares Balance at end of period, shares Treasury Stock, Shares Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Philippine Peso Philippines, Pesos Employee Separation Costs Employee Severance [Member] Carrying Value Reported Value Measurement [Member] Net Sales by Product Group and End Market Revenue from Contract with Customer [Text Block] Accounts receivable sold Accounts Receivable Sold without Recourse Accounts Receivable Sold without Recourse Total equity Balance at beginning of period Balance at end of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Interim Financial Statements Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Right of use assets acquired through operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Recognized actuarial loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Additional paid-in capital Additional Paid in Capital Net sales Revenues Foreign currency (gain) loss, net Foreign Currency Transaction Gain (Loss), before Tax Number of annual borrowings Debt Instrument, Number of Annual Borrowings, Maximum Debt Instrument, Number of Annual Borrowings, Maximum Income tax expense Income tax expense Income Tax Expense (Benefit) Cash, cash equivalents and restricted cash, beginning of period Cash, cash equivalents and restricted cash, end of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Accrued expenses Total accrued expenses Accrued Liabilities, Current Diluted (in dollars per share) Earnings Per Share, Diluted Short-term finance lease liabilities Finance Lease, Liability, Current Proceeds from sale of short-term investments Proceeds from Sale of Debt Securities, Available-for-sale Local Phone Number Local Phone Number Derivative Instruments and Hedging Activities Disclosure [Abstract] Summary of short-term borrowings and long-term debt Schedule of Debt [Table Text Block] Debt Long-term Debt, Gross Depreciation expense Depreciation Entity Address, Address Line One Entity Address, Address Line One Term Loan Due Seven Years from Initial Draw Term Loan - October 2021 [Member] Term Loan - October 2021 Contract liabilities Contract with Customer, Liability Entity Emerging Growth Company Entity Emerging Growth Company Credit facility, borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Maximum Maximum [Member] Preferred stock designated Series A, shares authorized Preferred Stock, Shares Authorized Noncontrolling Interest in Subsidiaries Noncontrolling Interest [Member] Payments for short-term investments Payments to Acquire Short-term Investments Retained Earnings Retained Earnings [Member] Measurement Basis [Axis] Measurement Basis [Axis] Finance Lease, Liability, Current, Statement of Financial Position [Extensible List] Finance Lease, Liability, Current, Statement of Financial Position [Extensible List] Components of net periodic pension cost Schedule of Net Benefit Costs [Table Text Block] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Short-term term loans, variable rate Short term term loan, variable rate [Member] Short term term loan, variable rate [Member] Schedule of restructuring reserve by type of cost Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Trading Symbol Trading Symbol Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Property, Plant And Equipment Property, Plant and Equipment Disclosure [Text Block] Fair Value By Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Treasury stock, at cost, 46,151 and 46,094 shares in 2021 and 2020, respectively Treasury Stock, Value Facility Costs Facility Closing [Member] Earnings Per Share Earnings Per Share [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Factoring of Accounts Receivable [Line Items] Factoring of Accounts Receivable [Line Items] [Line Items] for Factoring of Accounts Receivable [Table] Current liabilities: Liabilities, Current [Abstract] Entity Shell Company Entity Shell Company Payment for Pension and Other Postretirement Benefits Payment for Pension and Other Postretirement Benefits Treasury stock acquired through surrender of shares for tax withholding, shares Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Factoring of Accounts Receivable Factoring of Accounts Receivable [Text Block] Factoring of Accounts Receivable Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Term loan, applicable bank rate plus 1.98%, due December 2028 Term Loan Due December 2028 [Member] Term Loan Due December 2028 [Member] Short-term investments (amortized cost of $244,627 and $133,744 in 2021 and 2020, respectively) Short-term Investments