Accounting Changes and Error Corrections [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] ASU 2017-07 Accounting Standards Update 2017-07 [Member] Accounting Standards Update 2017-07 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Operating income Operating Income (Loss) Other (income) expense, net Other Nonoperating Income (Expense) Equity [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Defined Benefit Pension Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Foreign Currency Translation Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Total AOCI Including Portion Attributable to Noncontrolling Interest [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Other comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts reclassified from accumulated other comprehensive income (loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Ending balance Earnings Per Share [Abstract] Computation of basic and diluted earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] 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] Retirement Benefits [Abstract] Pension Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Payables and Accruals [Abstract] Summary of accrued expenses Schedule of Accrued Liabilities [Table Text Block] Equity and Accumulated Other Comprehensive Income (Loss) Stockholders' Equity Note Disclosure [Text Block] Revenue from Contract with Customer [Abstract] Net sales by product group and end market Disaggregation of Revenue [Table Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Revenue from Contract with Customer Revenue from Contract with Customer [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] End Market Distribution Channel Concentration Risk [Member] Distribution Channel Concentration Risk [Member] Contract with Customer, Sales Channel [Axis] Contract with Customer, Sales Channel [Axis] Contract with Customer, Sales Channel [Domain] Contract with Customer, Sales Channel [Domain] Communications (smartphones, tablets, handheld devices) Sales Channel, Communications [Member] Sales Channel, Communications [Member] Automotive, industrial and other (driver assist, infotainment, safety, performance) Sales Channel, Automotive, Industrial And Other [Member] Sales Channel, Automotive, Industrial And Other [Member] Computing (datacenter, infrastructure, PC/laptop, storage) Sales Channel, Computing [Member] Sales Channel, Computing [Member] Consumer (set-top boxes, televisions, connected home, personal electronics, visual imaging) Sales Channel, Directly to Consumer [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total net sales Concentration Risk, Percentage Other Income and Expenses [Abstract] Schedule of other income and expense Schedule of Other Nonoperating Income (Expense) [Table Text Block] Debt Disclosure [Abstract] Debt Debt Disclosure [Text Block] Income Statement [Abstract] Net sales Revenue, Net Cost of sales Cost of Goods and Services Sold Gross profit Gross Profit Selling, general and administrative Selling, General and Administrative Expense Research and development Research and Development Expense Gain on sale of real estate Gain (Loss) on Disposition of Assets Total operating expenses Operating Expenses Operating income Interest expense Interest Expense Interest expense, related party Interest Expense, Related Party Other (income) expense, net Total other expense, net Nonoperating Income (Expense) Income before taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Amkor Net Income (Loss) Attributable to Parent Net income attributable to Amkor per common share: Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Shares used in computing per common share amounts: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Nanium S.A. Nanium S.A. [Member] Nanium S.A. [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Ownership interest acquired (as a percent) Business Acquisition, Percentage of Voting Interests Acquired Net Sales by Product Group and End Market Revenue from Contract with Customer [Text Block] Property, Plant and Equipment [Abstract] Summary of property, plant and equipment and depreciation expense Property, Plant and Equipment [Table Text Block] Depreciation expense Depreciation Changes in equity Schedule of Stockholders Equity [Table Text Block] Changes in accumulated other comprehensive income (loss), net of tax Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Income Tax Disclosure [Abstract] Income tax expense Gross unrecognized tax benefits Unrecognized Tax Benefits Payroll and benefits Employee-related Liabilities, Current Income taxes payable Accrued Income Taxes, Current Accrued settlement costs Accrued settlement costs, current Accrued settlement costs, current Deferred revenue and customer advances Deferred Revenue and Credits, Current Accrued severance plan obligations Supplemental Unemployment Benefits, Severance Benefits Accrued interest Interest Payable, Current Other accrued expenses Other Accrued Liabilities, Current Total accrued expenses Accrued Liabilities, Current Components of net periodic pension cost Schedule of Net Benefit Costs [Table Text Block] Summary of defined contribution expense Defined Contribution Plan Disclosures [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities Excluded from Computation of Earnings Per Share, by Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Stock options and restricted share awards Stock Options And Restricted Shares [Member] Stock options and restricted shares. Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Stock options and restricted share awards Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents, Current Accounts receivable, net of allowances Accounts Receivable, Net, Current Inventories Inventory, Net Other current assets Other Assets, Current Total current assets Assets, Current Property, plant and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Restricted cash Restricted Cash and Cash Equivalents, Noncurrent Other assets Other Assets, Noncurrent Total assets Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Short-term borrowings and current portion of long-term debt Debt, Current Trade accounts payable Accounts Payable, Current Capital expenditures payable Capital expenditures payable Amount owed for capital expenditures. Accrued expenses Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Pension and severance obligations Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent Other non-current liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 16) Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.001 par value, 10,000 shares authorized, designated Series A, none issued Preferred Stock, Value, Issued Common stock, $0.001 par value, 500,000 shares authorized; 285,322 and 285,129 shares issued; and 239,366 and 239,184 shares outstanding in 2018 and 2017, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Retained earnings (accumulated deficit) Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Treasury stock, at cost, 45,956 and 45,945 shares, in 2018 and 2017, respectively Treasury Stock, Value Total Amkor stockholders’ equity Stockholders' Equity Attributable to Parent Non-controlling interests in subsidiaries Stockholders' Equity Attributable to Noncontrolling Interest Total equity Total liabilities and equity Liabilities and Equity Net income attributable to Amkor common stockholders Net Income (Loss) Available to Common Stockholders, Basic Weighted-average number of common shares outstanding — basic Effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Stock options and restricted share awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted-average number of common shares outstanding — diluted Net income attributable to Amkor per common share: Earnings Per Share, Basic and Diluted [Abstract] Income Taxes Income Tax Disclosure [Text Block] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Korea KOREA, REPUBLIC OF Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Proceeds from sale of property, plant and equipment Proceeds from Sale of Property, Plant, and Equipment Percentage of proceeds received Percentage of Proceeds Received The percentage of proceeds received from sale of property, plant, and equipment Pre-tax gain at close Factoring of Accounts Receivable [Abstract] Factoring of Accounts Receivable [Abstract] Factoring of Accounts Receivable [Table] Factoring of Accounts Receivable [Table] Factoring of Accounts Receivable [Table] Factoring of Accounts Receivable [Axis] Factoring of Accounts Receivable [Axis] Factoring of Accounts Receivable [Axis] Factoring of Accounts Receivable [Domain] Factoring of Accounts Receivable [Domain] [Domain] for Factoring of Accounts Receivable [Axis] Total Factored Total Factored [Member] Total Accounts Receivable Factored [Member] Discounts and Fees Factoring Fees [Member] Factoring Fees [Member] Factoring of Accounts Receivable [Line Items] Factoring of Accounts Receivable [Line Items] [Line Items] for Factoring of Accounts Receivable [Table] Accounts receivable sold Accounts Receivable Sold without Recourse Accounts Receivable Sold without Recourse Accounting Policies [Abstract] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Course of recognition Revenue From Contract With Customer, Period Of Recognition Revenue From Contract With Customer, Period Of Recognition Unbilled receivables Unbilled Receivables, Current New Accounting Standards New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Line of Credit Line of Credit [Member] Senior Notes Senior Notes [Member] Subsidiary Term Loans Subsidiary Term Loans [Member] Subsidiary Term Loans [Member] Term Loan Medium-term Notes [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 Senior Secured Revolving Credit Facility due December 2019 [Member] Senior Secured Revolving Credit Facility due December 2019 [Member] 6.625% Senior notes, due June 2021 (2) Senior Notes Due June 2021 [Member] Senior notes due 2021. 6.375% Senior notes, due October 2022 Senior Notes Due October 2022 [Member] Senior Notes Due October 2022 [Member] $75 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due September 2019 Revolving Credit Facility Due September 2018 [Member] Revolving Credit Facility Due September 2018 [Member] Term loan, LIBOR plus 2.70%, due December 2019 Term Loan Due December 2019 [Member] Term Loan Due December 2019 [Member] Term loan, foreign currency funding-linked base rate plus 1.32%, due May 2020 Term Loan Due May 2020 $150M [Member] Term Loan Due May 2020 $150M [Member] Term loan, fixed rate at 3.70%, due May 2020 Fixed Rate Term Loan Due May 2020 [Member] Fixed Rate Term Loan Due May 2020 [Member] Term loan, fund floating rate plus 1.60%, due June 2020 Term Loan Due June 2020 [Member] Term Loan Due June 2020[Member] Short-term term loans, variable rate Short term term loan, variable rate [Member] Short term term loan, variable rate [Member] Term loans, fixed rate at 0.53%, due April 2018 Term Loans Due April 2018 [Member] Term Loans Due April 2018 [Member] Term loan, fixed rate at 0.86%, due June 2022 Term Loan Due June 2022 [Member] Term Loan Due June 2022 [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] Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) Revolving credit facility due November 2020 [Member] Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) [Member] Term loan, LIBOR plus 1.80%, due December 2019 (China) Term Loan, LIBOR plus 1.80% due December 2019 [Member] Term Loan, LIBOR plus 1.80% due December 2019 [Member] Senior secured revolving credit facility due July 2023 Senior Secured Revolving Credit Facility due July 2023 [Member] Senior Secured Revolving Credit Facility due July 2023 [Member] Term loan, fixed at 1.30% due July 2023 Term Loan Due July 2023 [Member] Term Loan Due July 2023 [Member] Japan JAPAN Taiwan TAIWAN, PROVINCE OF CHINA China CHINA Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Letter of Credit Letter of Credit [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] TIBOR Tokyo Interbank Offered Rate (TIBOR) [Member] Tokyo Interbank Offered Rate (TIBOR) [Member] LIBOR London Interbank Offered Rate (LIBOR) [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Short-term borrowings and long-term debt Long-term Debt Including Related Party, Gross Amount of long-term debt, including related party debt, before deduction of unamortized discount or premium. Less: Unamortized premium and deferred debt costs, net Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Less: Short-term borrowings and current portion of long-term debt Debt, Including Due to Related Party, Current Debt, Including Due to Related Party, Current Long-term debt Non Current Long term Debt Including Related Party Non current long-term debt including related party. Basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Credit facility, borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Stated interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Standby letters of credit outstanding Letters of Credit Outstanding, Amount Face amount of debt Debt Instrument, Face Amount Debt redemption price Debt Instrument, Redemption Price, Percentage Interest rate at period end (as a percent) Line of Credit Facility, Interest Rate at Period End Proceeds from revolving credit facilities Proceeds from Lines of Credit Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Land Land [Member] Land use rights Use Rights [Member] Buildings and improvements Building and Building Improvements [Member] Machinery and equipment Machinery and Equipment [Member] Software and computer equipment Software and Computer Equipment [Member] Software and Computer Equipment [Member] Furniture, fixtures and other equipment Furniture and Fixtures [Member] Construction in progress Construction in Progress [Member] Total property, plant and equipment Property, Plant and Equipment, Gross Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total property, plant and equipment, net Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Fair Value Measurements Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash equivalent money market funds Cash and Cash Equivalents, Fair Value Disclosure Restricted cash money market funds Restricted Cash Fair Value Disclosure Restricted Cash Fair Value Disclosure Fair Value By Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Senior notes Revolving credit facilities and term loans Subsidiary Term Loans and Revolving Credit Facilities [Member] Subsidiary Term Loans and Revolving Credit Facilities [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Total debt Debt Instrument, Fair Value Disclosure Document and Entity Information [Abstract] Document And Entity Information. Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Recurring fair value measurements Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] 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] Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] As Previously Reported Scenario, Previously Reported [Member] New Accounting Pronouncement Adjustment Restatement Adjustment [Member] ASU 2014-09 Accounting Standards Update 2014-09 [Member] Adjustment to Accumulated Deficit Retained Earnings [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Net sales Net income Net income attributable to Amkor Net loss attributable to Amkor per common share - diluted (in dollars per share) Accounts receivable, net Inventories Other assets Accrued expenses Other non-current liabilities Accumulated deficit Adjustment to accumulated deficit Cumulative Effect of New Accounting Principle in Period of Adoption Acquisition Business Combination Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Net income Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Adjustments to unrealized components of defined benefit pension plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to non-controlling interests Comprehensive income attributable to Amkor Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of the impacted previously reported results Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Property, Plant And Equipment Property, Plant and Equipment Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Interim Financial Statements Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Summary of short-term borrowings and long-term debt Schedule of Debt [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Earnings Per Share Earnings Per Share [Text Block] Significant Accounting Policies Significant Accounting Policies [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Accounting Standards Update, Recently Adopted Standards and Recently Issued Standards New Accounting Pronouncements, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Unbilled Receivables Trade and Other Accounts Receivable, Unbilled Receivables, Policy [Policy Text Block] Inventories Inventory, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Interest income Interest Income, Deposits with Financial Institutions Foreign currency (gain) loss, net Foreign Currency Transaction Gain (Loss), before Tax 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). Other (income) expense, net Other Income and Expense Other Income and Other Expense Disclosure [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Other operating activities and non-cash items Other Noncash Income (Expense) Changes in assets and liabilities Increase (Decrease) in Operating Capital Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Payments for property, plant and equipment Payments to Acquire Property, Plant, and Equipment Acquisition of business, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Other investing activities Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from short-term debt Proceeds from Short-term Debt Payments of short-term debt Repayments of Short-term Debt Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Payments of long-term debt Repayments of Long-term Debt Payment of deferred consideration for purchase of facility Final Installment Payment for Previous Acquisition The cash outflow attributable to a prior period acquisition whereby a portion of the fixed consideration was deferred to the current period. Payments of capital lease obligations Repayments of Long-term Capital Lease Obligations Other financing activities Proceeds from (Payments for) Other Financing Activities Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities 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 Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents and restricted cash, beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash, end of period Non-cash investing and financing activities: Noncash Investing and Financing Items [Abstract] Property, plant and equipment included in capital expenditures payable Capital Expenditures Incurred but Not yet Paid Equipment acquired through capital lease Capital Lease Obligations Incurred Factoring of Accounts Receivable Factoring of Accounts Receivable [Text Block] Factoring of Accounts Receivable Defined contribution expense Defined Contribution Plan, Cost Preferred stock designated Series A, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock designated Series A, shares authorized Preferred Stock, Shares Authorized Preferred stock designated Series A, shares issued Preferred Stock, Shares Issued Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Treasury stock, shares Treasury Stock, Shares Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Recognized actuarial (gain) loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Net periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Accrued Expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Advanced products Advanced Products [Member] Advanced Products [Member] Mainstream products Mainstream Products [Member] Mainstream Products [Member] Net sales by product group Revenue from Contract with Customer, Excluding Assessed Tax Schedule of Stockholders Equity [Table] Schedule of Stockholders Equity [Table] Schedule of Stockholders Equity [Table] Attributable to Amkor Parent [Member] Attributable to Non-controlling Interests Noncontrolling Interest [Member] Schedule of Stockholders Equity [Line Items] Schedule of Stockholders Equity [Line Items] Schedule of Stockholders Equity [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Other comprehensive income (loss) Issuance of stock through employee share-based compensation plans Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Treasury stock acquired through surrender of shares for tax withholding Adjustments Related to Tax Withholding for Share-based Compensation Share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Subsidiary dividends paid to non-controlling interests Payments of Ordinary Dividends, Noncontrolling Interest