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(Loss) Including Portion Attributable to Noncontrolling Interest [Member] Schedule of amounts recognized in balance sheet Schedule of Amounts Recognized in Balance Sheet [Table Text Block] Other non-current liabilities Deferred Income Tax Liabilities, Net Factoring Fees Factoring Fees [Member] Factoring Fees [Member] Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract] Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract] Schedule of effective income tax rate reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Finance lease machinery and equipment Assets Held under Capital Leases [Member] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Trade accounts payable Accounts Payable, Current Depreciation and amortization Depreciation, Depletion and Amortization Total Amkor Stockholders’ Equity Parent [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Inventories Increase (Decrease) in Inventories Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Financial Instruments [Domain] Financial Instruments [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 Short-term investments, amortized cost Debt Securities, Available-for-sale, Amortized Cost, Current Cost of sales Cost of Goods and Services Sold Restructuring and Related Activities [Abstract] Entity Central Index Key Entity Central Index Key Settlement (1) Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement Net lease cost Lease, Cost Current: Current Federal, State and Local, Tax Expense (Benefit) [Abstract] Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Reductions for tax positions of prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Within 1 year, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Other non-current liabilities Other Liabilities, Noncurrent Projected benefit obligation at January 1 Projected benefit obligation at December 31 Defined Benefit Plan, Benefit Obligation Operating lease right of use assets Deferred Tax Liabilities, Operating Lease, Right-of-use Asset Deferred Tax Liabilities, Operating Lease, Right-of-use Asset Interest income Interest Income, Deposits with Financial Institutions Debt Instrument [Line Items] Debt Instrument [Line Items] Trading Symbol Trading Symbol Fair value Derivative Asset Accrued Expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Other Deferred Tax Liabilities, Other Consumer (AR & gaming, connected home, home electronics, wearables) Sales Channel, Consumer Goods [Member] Sales Channel, Consumer Goods[Member] Number of shares fully vested and expected to vest Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Proceeds from sale of short-term investments Proceeds from Sale of Debt Securities, Available-for-sale Long-term debt Long-term debt Long-term Debt, Excluding Current Maturities Share-based compensation Share-based Payment Arrangement, Expense Expiration of net operating losses and credits Effective Income Tax Rate Reconciliation, Expiration of Net Operating Losses Effective Income Tax Rate Reconciliation, Expiration of Net Operating Losses Average Remaining Contractual Term Exercisable (years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Net income attributable to Amkor per common share: Earnings Per Share, Basic and Diluted [Abstract] Settlement (1) Defined Benefit Plan, Plan Assets, Payment for Settlement Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Payables and Accruals [Abstract] Payables and Accruals [Abstract] Schedule of income before income tax, domestic and foreign Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Construction in progress Construction in Progress [Member] 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 Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Current assets: Assets, Current [Abstract] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Other financing activities Proceeds from (Payments for) Other Financing Activities U.S. Federal Internal Revenue Service (IRS) [Member] Number of shares exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Total other comprehensive income (loss) Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Accrued interest Interest Payable, Current Accounts Receivable Sold without Recourse Accounts Receivable Sold without Recourse Accounts Receivable Sold without Recourse 2007 Plan Two Thousand Seven Equity Incentive Plan [Member] Dividends Stockholders' Equity Note Disclosure [Text Block] Reductions from lapse of statutes of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Measurement Basis [Axis] Measurement Basis [Axis] Antidilutive effect of potential shares of common stock that were excluded from diluted earnings per share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Other Current Assets Other Current Assets [Text Block] Fair Value Measurements Fair Value of Financial Instruments, Policy [Policy Text Block] Auditor Firm ID Auditor Firm ID Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Fair Value Measurement Portion at Fair Value Measurement [Member] Change in projected benefit obligation: Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Buildings and improvements Buildings and improvements Building and Building Improvements [Member] Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Notional Value Derivative Asset, Notional Amount Weighted Average Grant-Date Fair Value Awards vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Defined Benefit Plan, Liability Liability, Defined Benefit Plan [Abstract] Credit facility, borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Operating cash flows for finance leases Finance Lease, Interest Payment on Liability Summary of valuation allowance Summary of Valuation Allowance [Table Text Block] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Discount rate for determining net periodic pension cost (as a percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Severance payments (1) Payments for Employee Severance Lump-sum payments related to termination of employment (employees and directors), based on length of service, seniority and average monthly wages at the time of termination, which is not related to restructurings, pension plans or other post retirement benefit plans. Severance benefits are estimated assuming all eligible employees were to terminate their employment at the balance sheet date. Other current assets Other Assets, Current Rate of compensation increase for determining net periodic pension cost (as a percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Asset-backed securities Asset-backed Securities [Member] Net amount recognized at year end Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Other assets Increase (Decrease) in Other Noncurrent Assets Total cumulative charges incurred to date Restructuring and Related Cost, Cost Incurred to Date Less current portion of accrued severance plan obligations (Note 10) Postemployment Benefits Liability, Current U.S. federal statutory income tax rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Short-term term loans, variable rates Short term term loan, variable rate [Member] Short term term loan, variable rate [Member] After 10 Years, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Basis of Presentation Basis Of Presentation [Policy Text Block] Basis Of Presentation [Policy Text Block] Balance at Beginning of Period Balance at End of Period SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Treasury notes Treasury Notes [Member] Treasury Notes Income taxes payable Accrued Income Taxes, Current Inventories Inventory, Policy [Policy Text Block] Foreign Current Foreign Tax Expense (Benefit) Description of Business Nature of Operations [Text Block] Finance lease machinery and equipment Finance Lease, Right-of-Use Asset, before Accumulated Amortization Factoring of Accounts Receivable [Line Items] Factoring of Accounts Receivable [Line Items] [Line Items] for Factoring of Accounts Receivable [Table] Within 1 year, Fair Value Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Settlements and changes in uncertain tax positions Effective Income Tax Rate Reconciliation, Tax Contingency, Amount Factoring of Accounts Receivable Factoring of Accounts Receivable [Text Block] Factoring of Accounts Receivable Philippines, Pesos Philippines, Pesos Term loan, applicable bank rate plus 1.98%, due December 2028 Term Loan Due December 2028 [Member] Term Loan Due December 2028 [Member]