Debt Disclosure [Abstract] Debt Debt Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Interim Financial Statements Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Property, Plant and Equipment [Abstract] Property, Plant And Equipment Property, Plant and Equipment Disclosure [Text Block] Property, Plant and Equipment [Table] 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] Construction in progress Construction in Progress [Member] Name of Property [Axis] Name of Property [Axis] Name of Property [Domain] Name of Property [Domain] K5 Facility K5 Facility [Member] K5 Facility [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Korea KOREA, REPUBLIC OF Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Depreciation Depreciation Property, plant and equipment, gross Property, Plant and Equipment, Gross 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 Gain (Loss) on Disposition of Property Plant Equipment Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Fair Value Disclosures [Abstract] 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 [Member] Portion at Fair Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior notes (Level 1) Senior Notes [Member] Revolving credit facilities and term loans (Level 2) Subsidiary Term Loans and Revolving Credit Facilities [Member] Subsidiary Term Loans and Revolving Credit Facilities [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] 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] Fair value disclosure for debt Debt Instrument, Fair Value Disclosure Inventory Disclosure [Abstract] Inventories Inventory, Net, Combining Work in Process and Raw Materials Alternative [Abstract] Raw materials and purchased components Inventory, Raw Materials, Net of Reserves Work-in-process Inventory, Work in Process, Net of Reserves Total inventories Inventory, Net Business Combinations [Abstract] Acquisition Business Combination Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 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, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Total other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Comprehensive income attributable to Amkor Comprehensive Income (Loss), Net of Tax, Attributable to Parent Summary of Short term Borrowings And Long term Debt Schedule of Debt [Table Text Block] Earnings Per Share [Abstract] Net income available to Amkor common stockholders Net Income (Loss) Available to Common Stockholders, Basic Weighted-average number of common shares outstanding — basic Weighted Average Number of 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 Weighted Average Number of Shares Outstanding, Diluted Net income attributable to Amkor per common share: Earnings Per Share, Basic and Diluted [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] 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] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Weighted Average Weighted Average [Member] 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] Line of Credit Line of Credit [Member] Senior Notes Term Loan Medium-term Notes [Member] Subsidiary Term Loans Subsidiary Term Loans [Member] Subsidiary Term Loans [Member] Japan JAPAN Taiwan TAIWAN, PROVINCE OF CHINA China CHINA 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 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 June 2018 Revolving Credit Facility Due June 2018 [Member] Revolving Credit Facility Due June 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] Term loan, LIBOR plus 2.60%, due May 2018 Term Loan Due May 2018 [Member] Term Loan Due May 2018 [Member] Term loan, foreign currency funding-linked base rate plus 1.33%, due May 2020 Term Loan Due May 2020 $80M [Member] Term Loan Due May 2020 1.55% $80M [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] Debt Instrument [Line Items] Debt Instrument [Line Items] Credit facility, borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate 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 Redemption notice, amount to be redeemed Extinguishment of Debt, Amount Long-term debt including related party, gross Long-term Debt Including Related Party, Gross Amount of long-term debt, including related party debt, before deduction of unamortized discount or premium. Current portion of long-term debt, related party Due to Related Parties, Current Redemption price (as a percent) Debt Instrument, Redemption Price, Percentage Loss on premium paid for retirement of debt Payments of Debt Extinguishment Costs Write off of Deferred Debt Issuance Cost Write off of Deferred Debt Issuance Cost Long-term debt, related party Due to Related Parties, Noncurrent Interest rate at period end (as a percent) Line of Credit Facility, Interest Rate at Period End Proceeds from lines of credit Proceeds from Lines of Credit Repayments of debt Repayments of Debt Amount of debt agreement Debt Instrument, Face Amount Periodic principal payment Debt Instrument, Periodic Payment, Principal Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Compensation and Retirement Disclosure [Abstract] Pension Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Inventories Inventory Disclosure [Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Foreign Pension Plans Foreign Postretirement Benefit Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Recognized actuarial loss Defined Benefit Plan, Actuarial Gain (Loss) Net periodic pension cost Defined Benefit Plan, Net Periodic Benefit Cost Equity [Abstract] Equity and Accumulated Other Comprehensive Income (Loss) Stockholders' Equity Note Disclosure [Text Block] Long-term debt including related party, gross 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 (including related party) Non Current Long term Debt Including Related Party Non current long-term debt including related party. Fair Value Measurements Fair Value Disclosures [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Changes in equity attributable to both Company and noncontrolling interests Schedule of Stockholders Equity [Table Text Block] Changes in accumulated other comprehensive income (loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Commitments and Contingencies Commitments and Contingencies, Policy [Policy Text Block] Payables and Accruals [Abstract] Summarized Accrued expenses Schedule of Accrued Liabilities [Table Text Block] 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 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 Operating Income (Loss) Interest expense Interest Expense Interest expense, related party Interest Expense, Related Party Other (income) expense, net Other Nonoperating Income (Expense) 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 attributable to non-controlling interests Net income attributable to Amkor Net Income (Loss) Attributable to Parent Net income attributable to Amkor per common share: Shares used in computing per common share amounts: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Diluted (in shares) 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, 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 (Level 1) Cash and Cash Equivalents, Fair Value Disclosure Restricted cash money market funds (Level 1) Restricted Cash Fair Value Disclosure Restricted Cash Fair Value Disclosure New Accounting Pronouncements and Changes in Accounting Principles [Abstract] New Accounting Standards New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Components of net periodic pension cost Schedule of Net Benefit Costs [Table Text Block] Defined contribution plan disclosures Defined Contribution Plan Disclosures [Table Text Block] Valuation of money market funds and restricted cash using quoted market prices in active markets for identical assets Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Financial instruments that are not recorded at fair value Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Earnings Per Share Earnings Per Share [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 shares 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 Other Income and Expenses [Abstract] Schedule of Other Nonoperating Income (Expense) Schedule of Other Nonoperating Income (Expense) [Table Text Block] Interest income Interest Income, Deposits with Financial Institutions Foreign currency (gain) loss, net Foreign Currency Transaction Gain (Loss), before Tax Loss on debt retirement Gain (Loss) on Extinguishment of Debt 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). Total other (income) expense, net 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 Ending balance 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 [Member] Total Factored [Member] Total Accounts Receivable Factored [Member] Factoring Fees [Member] 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 without recourse Accounts Receivable Sold without Recourse Accounts Receivable Sold without Recourse Payroll and benefits Employee-related Liabilities, Current Deferred revenue and customer advances Deferred Revenue and Credits, Current Income taxes payable Accrued Income Taxes, Current Accrued settlement costs Accrued settlement costs, current Accrued settlement costs, current Accrued interest Interest Payable, Current Accrued severance plan obligations Supplemental Unemployment Benefits, Severance Benefits Other accrued expenses Other Accrued Liabilities, Current Total accrued expenses Accrued Liabilities, Current Inventories Schedule of Inventory, Current [Table Text Block] Accrued Expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income 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 revolving credit facilities Payments of revolving credit facilities Repayments of Lines of Credit Proceeds from short-term debt Proceeds from Short-term Debt Payments of short-term debt Repayments of Short-term Debt Payments of long-term debt Repayments of Long-term Debt Payments of long-term debt, related party Repayments of Related Party 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 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 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, 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, 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 Defined contribution expense Defined Contribution Plan, Cost Recognized Income tax expense Gross unrecognized tax benefits Unrecognized Tax Benefits Statement of Financial Position [Abstract] Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] 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 Factoring of Accounts Receivable Factoring of Accounts Receivable [Table Text Block] [Table Text Block] for Factoring of Accounts Receivable [Table] 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 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 Pension and Other Postretirement and Postemployment Benefit Plans, Liabilities, Noncurrent Other non-current liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 15) Commitments and Contingencies 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; 285,019 and 284,479 shares issued; and 239,079 and 238,665 shares outstanding, in 2017 and 2016, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated deficit Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Treasury stock, at cost, 45,940 and 45,814 shares, in 2017 and 2016, 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 Schedule of Property, Plant and Equipment [Table] 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] Total property, plant and equipment Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total property, plant and equipment, net 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 Other Income and Expense Other Income and Other Expense Disclosure [Text Block] Computation of basic and diluted earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] 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] Schedule of Stockholders Equity [Table] Schedule of Stockholders Equity [Table] Schedule of Stockholders Equity [Table] Amkor Parent [Member] Noncontrolling Interest 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 Summary of Property, plant and equipment Property, Plant and Equipment [Table Text Block]