Revenue from Contract with Customer [Abstract] Contract costs capitalized during the period Contract Costs Capitalized During the Period Capitalized contract costs associated with new contracts entered into during the period. Costs amortized during the period Capitalized Contract Cost, Amortization Change in capitalized contract cost, other Change in Capitalized Contract Cost, Other Change in capitalized contract cost, other Balance of costs to obtain a contract Capitalized Contract Cost, Net Retirement Benefits, Description [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Plans [Member] Pension Plan [Member] Supplemental Executive Retirement Plan (SERP) [Member] Supplemental Employee Retirement Plan [Member] Other Postretirement Plans [Member] Other Postretirement Benefits 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 assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of prior service cost (credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Recognized actuarial loss (gain) Defined Benefit Plan, Amortization of Gain (Loss) Net Periodic Cost (Benefit) for the Year Net Periodic Benefit For Defined Benefit Pension Plans Excluding Early Retirement Program, Special Separation Benefit Expense, Curtailment And Settlement The net periodic benefit or expense for defined benefit pension plans excluding the early retirement program and special separation benefit expense, curtailment, settlement and other programs separately disclosed in the financial statements. Curtailment Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Settlement Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Early retirement programs and special separation benefit expense Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits Total Cost (Benefit) for the Year Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Current year actuarial gain (loss) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Current year prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax Amortization of prior service credit (cost) Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Recognized net actuarial gain (loss) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Curtailments and settlements Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax Total Recognized in Other Comprehensive Income (Before Tax Effects) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects) Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Foreign Currency Translation Adjustment [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Unrealized Gains (Losses) on Available- for- Sale Securities [Member] AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Pension and Other Postretirement Plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Net Actuarial Loss [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Net Prior Service Cost [Member] Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Curtailments and settlements Included in Net Income [Member] AccumulatedDefinedBenefitPlansAdjustmentCurtailmentGainsIncludedInNetIncome [Member] Accumulated other comprehensive (income) loss related to the curtailment gains included in net income component of defined benefit plans attributable to the parent. Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Cash Flow Hedges Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Other Comprehensive Income (Loss) [Line Items] Other Comprehensive Income (Loss) [Line Items] [Line Items] for Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from AOCI, Current Period, Tax Reclassification from AOCI, Current Period, Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Other Comprehensive Income (Loss), Before Tax Other Comprehensive Income (Loss), before Tax Other Comprehensive Income (Loss), Income Tax Other Comprehensive Income (Loss), Tax Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization and Nature of Operations Nature of Operations [Text Block] Schedule of Product Information [Table] Schedule of Product Information [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] JacksonvilleFL [Member] JacksonvilleFL [Member] JacksonvilleFL [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Segments [Axis] Segments [Axis] Segment [Domain] Segments [Domain] Education [Member] Education [Member] Education [Member] Television Broadcasting [Member] Television Broadcasting [Member] Television Broadcasting [Member] Product Information [Line Items] Product Information [Line Items] Number of education business categories Number Of Education Business Categories Number of categories that comprise Kaplan's businesses Number of television broadcast stations owned Number Of Television Broadcast Stations Owned Number of television broadcast stations owned by the Company. Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Defined Benefit Plan by Plan Asset Categories [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Cash equivalents and other short-term investments [Member] Cash Equivalents And Other Short Term Investments [Member] -- None. No documentation exists for this element. -- U.S. equities [Member] Defined Benefit Plan, Equity Securities, US [Member] International equities [Member] Defined Benefit Plan, Equity Securities, Non-US [Member] U.S. stock index fund [Member] Equity Funds, US [Member] An investment that pools funds from many investors to invest in a combination of underlying investments, primarily equity investments, domiciled in United States of America (US). Private investment fund [Member] Private Equity Funds [Member] Corporate debt securities [Member] Corporate Debt Securities [Member] Other fixed income securities [Member] Fixed Income Securities [Member] Total investments [Member] Total Investments [Member] -- None. No documentation exists for this element. -- Receivables (Payables) for settlement of investments purchased, net [Member] Receivables (Payables) [Member] -- None. No documentation exists for this element. -- Measurement Frequency [Axis] Measurement Frequency [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] Fair Value, Recurring [Member] Fair Value, Recurring [Member] Pension Plan [Member] Pension plan assets at fair value Defined Benefit Plan, Plan Assets, Amount Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class A Common Stock [Member] Common Class A [Member] Class B Common Stock [Member] Common Class B [Member] Statement [Line Items] Statement [Line Items] 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 Investments in marketable equity securities and other investments Investments In Marketable Equity Securities And Other Investments Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale which are intended to be held for less than one year or the normal operating cycle, whichever is longer. Also includes other current investments such as mutual funds. Accounts receivable, net Accounts and Other Receivables, Net, Current Income taxes receivable Income Taxes Receivable, Current Inventories and contracts in progress Inventory, Net of Allowances, Customer Advances and Progress Billings Other current assets Other Assets, Current Total Current Assets Assets, Current Property, Plant and Equipment, Net Property, Plant and Equipment, Net Lease Right-of-Use Assets Operating Lease, Right-of-Use Asset Investments in Affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Goodwill, Net Goodwill Indefinite-Lived Intangible Assets Indefinite-lived Intangible Assets (Excluding Goodwill) Amortized Intangible Assets, Net Finite-Lived Intangible Assets, Net Prepaid Pension Cost Assets for Plan Benefits, Defined Benefit Plan Deferred Income Taxes Deferred Income Tax Assets, Net Deferred Charges and Other Assets Other Assets, Noncurrent Total Assets Assets Liabilities and Equity Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Deferred revenue Deferred Revenue, Current Income taxes payable Accrued Income Taxes, Current Current portion of lease liabilities Operating Lease, Liability, Current Current portion of long-term debt Debt, Current Total Current Liabilities Liabilities, Current Accrued Compensation and Related Benefits Deferred Compensation Liability, Classified, Noncurrent Other Liabilities Other Liabilities, Noncurrent Deferred Income Taxes Deferred Income Tax Liabilities, Net Mandatorily Redeemable Noncontrolling Interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Noncurrent Lease Liabilities Operating Lease, Liability, Noncurrent Long-Term Debt Long-term Debt, Excluding Current Maturities Total Liabilities Liabilities Commitments and Contingencies (Note 18) Commitments and Contingencies Redeemable Noncontrolling Interests Redeemable Noncontrolling Interest, Equity, Carrying Amount Preferred Stock, $1 par value; 977,000 shares authorized, none issued Preferred Stock, Value, Issued Common Stockholders’ Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock Common Stock, Value, Issued Capital in excess of par value Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income, net of taxes Cumulative foreign currency translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Unrealized gain on pensions and other postretirement plans Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Cash flow hedges Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Cost of 14,687,763 and 14,699,041 shares of Class B common stock held in treasury Treasury Stock, Value Total Common Stockholders' Equity Stockholders' Equity Attributable to Parent Noncontrolling Interests Stockholders' Equity Attributable to Noncontrolling Interest Total Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total Liabilities and Equity Liabilities and Equity Contract with Customer, Liability Contract with Customer, Asset and Liability [Table Text Block] Capitalized Contract Cost Capitalized Contract Cost [Table Text Block] Quarterly Financial Information Disclosure [Abstract] Schedule of Quarterly Results of Operations and Comprehensive Income (Loss) Quarterly Financial Information [Table Text Block] Schedule Of Quarterly Impact From Certain Items Schedule Of Quarterly Impact From Certain Items [Table Text Block] Tabular disclosure Quarterly Impact From Certain Items. Income Tax Disclosure [Abstract] Income Taxes [Table] Income Taxes [Table] -- None. No documentation exists for this element. -- Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Capital loss carryforward [Member] Capital Loss Carryforward [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State [Member] State and Local Jurisdiction [Member] U.S. Federal [Member] Domestic Tax Authority [Member] non-U.S. [Member] Foreign Tax Authority [Member] Carryforwards Period [Axis] CarryforwardsPeriod [Axis] -- None. No documentation exists for this element. -- Carryforward Period [Domain] Carryforward Period [Domain] Carryforward Period Domain Through 2024 [Member] Loss Carryforwards Expirations Range One [Member] -- None. No documentation exists for this element. -- After 2024 [Member] Loss Carryforwards Expirations Range Two [Member] -- None. No documentation exists for this element. -- Segments [Axis] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Liability, Income Tax Benefit Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Liability, Income Tax Benefit Tax Cuts and Jobs Act, Decrease in Deferred Tax Liability due to Transition Tax Tax Cuts and Jobs Act, Decrease in Deferred Tax Liability due to Transition Tax Deferred income tax expense (benefit) Deferred Income Tax Expense (Benefit) Income tax loss carryforwards to expire Income Tax Loss Carryforwards Subject to Expiration Income tax loss carryforwards subject to expiration. Deferred state income tax asset Deferred Tax Assets, Operating Loss Carryforwards, State and Local Income tax loss carryforwards obtained as a result of prior stock acqusitions Tax Loss Carryforward Prior Stock Acquisition Utilized Income tax loss carryforwards obtained as a result of prior stock acqusitions to be fully utilized. Deferred tax assets with respect to U.S. Federal income tax loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Domestic Foreign tax credit carryforwards Foreign Tax Credit Carryforwards Foreign tax credits available to be credited against future U.S. Federal income tax liabilities. Deferred tax assets with respect to U.S. Federal foreign tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards, Foreign Tax Credit Carryforward, Valuation Allowance Tax Credit Carryforward, Valuation Allowance Tax loss carryforwards as a result of operating losses and prior stock acquisitions Operating Losses And Prior Stock Acqusitions Carryforward Tax loss carryforwards as a result of operating losses and prior stock acquisitions Deferred tax assets with respect to non U.S. income tax loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Foreign Valuation allowance against the deferred tax assets recorded for the tax losses carryforward Deferred Tax Asset Operating Losses And Prior Stock Acquisitions Carryforward Valuation Allowance Valuation allowance against the deferred tax assets recorded for the tax losses carryforward. Tax loss carryforwards from operating losses and prior stock acquisitions that can be carried forward indefinitely Operating Losses And Prior Stock Acqusitions Carryforward Indefinitely Tax loss carryforwards from operating losses and prior stock acquisitions that can be carried forward indefinitely. Tax loss carryforwards subject to expiration Operating Losses And Prior Stock Acqusitions Carryforward Subject To Expiration Tax loss carryforward resulting from operating losses and prior stock acquisitions subject to expiration. Carryforward amount Tax Credit Carryforward, Amount Non-U.S.deferred tax asset related to capital loss carryforwards Deferred Tax Assets, Capital Loss Carryforwards Valuation Allowance, Amount Deferred Tax Assets, Valuation Allowance Valuation allowance related to operating loss carryforwards Operating Loss Carryforwards, Valuation Allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Deferred income tax liabilities related to undistributed earnings of investments in non-U.S. subsidiaries Deferred Tax Liabilities, Undistributed Foreign Earnings Valuation allowance released Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Unrecognized tax benefit that would impact the effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Federal tax impact of unrecognized tax benefits that would impact the effective tax rate Federal Tax Impact Of Unrecognized Tax Benefits that Would Impact Effective Tax Rate The federal tax impact of the total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate. Interest accrued related to unrecognized tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Penalties accrued related to unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties Accrued Summary of Quarterly Operating Results and Comprehensive Income (Loss) (Unaudited) Quarterly Financial Information [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Student and Customer Relationships [Member] Customer Relationships [Member] Trade Names and Trademarks [Member] Trademarks and Trade Names [Member] Network affiliation agreements [Member] Contract-Based Intangible Assets [Member] Databases and Technology [Member] Database Rights [Member] Non-compete Agreements [Member] Noncompete Agreements [Member] Other [Member] Other Intangible Assets [Member] Amortized Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Useful Life (in years) Finite-Lived Intangible Asset, Useful Life Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Carrying Amount Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Franchise Rights [Member] Franchise Rights [Member] FCC licenses [Member] Operating and Broadcast Rights [Member] Licensure and Accreditation [Member] Licensure and Accreditation [Member] Licensure And Accreditation [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Net Carrying Amount Inventories, Contracts in Progress And Vehicle Floor Plan Payable [Abstract] Inventories, Contracts in Progress and Vehicle Floor Plan Payable [Abstract] Raw materials Inventory, Raw Materials, Net of Reserves Work-in-process Inventory, Work in Process, Net of Reserves Finished goods Inventory, Finished Goods, Net of Reserves Contracts in Progress Inventory for Long-term Contracts or Programs, Gross Inventories and contracts in progress Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Other Nonoperating Income (Expense) [Abstract] Other Non-Operating Income Other Income and Other Expense Disclosure [Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Noncurrent asset Current liability Liability, Defined Benefit Plan, Current Noncurrent liability Liability, Defined Benefit Plan, Noncurrent Recognized asset (liability) Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Investments [Abstract] Total cost Equity Securities, FV-NI, Cost Gross unrealized gains Equity Securities FV-NI, Accumulated Gross Unrealized Gain Amount of unrealized gain on investment on equity security measured at fair value with change in fair value recognized in net income (FV-NI). Gross unrealized losses EquitySecuritiesFVNIAccumulatedGrossUnrealizedLoss Amount of unrealized loss on investment on equity security measured at fair value with change in fair value recognized in net income (FV-NI). Total Fair Value Equity Securities, FV-NI Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Transaction [Axis] Transaction [Axis] Transaction [Axis] Transaction Type [Domain] Transaction Type [Domain] Transaction Type [Domain] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Higher Education [Member] Higher Education [Member] Higher Education [Member] Test Preparation [Member] Test Preparation [Member] Test Preparation [Member] Kaplan International [Member] Kaplan International [Member] Kaplan International [Member] Kaplan Corporate and Other [Member] Kaplan Corporate and Other [Member] Kaplan Corporate And Other [Member] Non U.S. [Member] Non-US [Member] UNITED KINGDOM UNITED KINGDOM Other Businesses [Member] Other Segments [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Purdue University Global [Member] Purdue University Global [Member] Purdue University Global Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Number of reportable segments Number of Reportable Segments Restructuring costs Restructuring Charges Accrued restructuring costs Restructuring Reserve Number of Stores Number of Stores Number of Restaurants Number of Restaurants Operating Revenues Revenues Foreign assets Entity Wide Disclosure On Geographic Areas Long-Lived Assets Excluding Goodwill And Other Intangible Assets In Foreign Countries Amount of long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets, goodwill, and other intangible assets located in foreign countries in total in which the entity holds assets. Accounts Receivable, after Allowance for Credit Loss Accounts Receivable, after Allowance for Credit Loss Accounts Receivable, after Allowance for Credit Loss, Noncurrent Accounts Receivable, after Allowance for Credit Loss, Noncurrent Advance Related To Kaplan University Transaction Advance Related To Kaplan University Transaction Advance related to Kaplan University Transaction. Capital Stock, Stock Awards, and Stock Options [Abstract] -- None. No documentation exists for this element. -- Activity Related to Stock Awards Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] Activity Related to Stock Options Share-based Payment Arrangement, Option, Activity [Table Text Block] Information related to Stock Options Outstanding and Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable [Table Text Block] Fair Value of Options Assumptions Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Antidilutive Weighted Average Restricted Stock and Options Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Interest rate, minimum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Interest rate, maximum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Volatility, minimum (percentage) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Volatility (percentage) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Volatility, maximum (percentage) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Income Taxes Income Tax Disclosure [Text Block] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments [Member] Operating Segments [Member] Corporate office [Member] Corporate, Non-Segment [Member] Intersegment Elimination [Member] Intersegment Eliminations [Member] Manufacturing [Member] Manufacturing [Member] Manufacturing business Graham Healthcare Group [Member] Graham Healthcare Group [Member] Graham Healthcare Group [Member] SocialCode [Member] SocialCode [Member] SocialCode [Member] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Reportable Subsegments [Member] Reportable Subsegments [Member] Intersubsegment Eliminations [Member] Intersubsegment Eliminations [Member] Professional (U.S.) [Member] Professional (U.S.) [Member] Professional (U.S.) [Member] Income (loss) from operations Operating Income (Loss) Equity in earnings (losses) of affiliates, net Income (Loss) from Equity Method Investments Interest expense, net Interest Income (Expense), Net Debt extinguishment costs Gain (Loss) on Extinguishment of Debt Non-operating pension and postretirement benefit income, net Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component Gain (loss) on marketable equity securities, net Equity Securities, FV-NI, Gain (Loss) Other income, net Other Nonoperating Income (Expense) Income Before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Depreciation of property, plant and equipment Depreciation Amortization of intangible assets and impairment of goodwill and other long-lived assets Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long-Lived Assets Amortization of intangible assets and impairment of goodwill and other long-lived assets during the period. Amortization of Intangible Assets Amortization of Intangible Assets Impairment of Long-Lived Assets Asset Impairment Charges Pension service cost Capital Expenditures Property, Plant and Equipment, Additions Identifiable Assets Identifiable Assets Identifiable assets by segment are those assets used in the Company's operations in each business segment. Marketable equity securities Total Assets Summary of Other Comprehensive Income (Loss) Comprehensive Income (Loss) [Table Text Block] Summary of Changes in Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Summary of Amounts and Line Items of Reclassifications out of Accumulated Other Comprehensive Income (Loss) Disclosure of Reclassification Amount [Text Block] Acquisitions And Dispositions [Abstract] Acquisitions and Dispositions Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Disposal Group, Not Discontinued Operation, Revenue Disposal Group, Not Discontinued Operation, Revenue Amount of revenue attributable to disposal group. Excludes discontinued operations. Disposal Group, Not Discontinued Operation, Operating Income Disposal Group, Not Discontinued Operation, Operating Income (Loss) Amount of operating income (loss) attributable to disposal group. Excludes discontinued operations. Property, Plant and Equipment [Abstract] Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Gains on cost method investments Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Impairment of goodwill and other long-lived assets Leases [Abstract] Operating lease cost Operating Lease, Cost Short-term and month-to-month lease cost Short Term and Month to Month Lease Cost Amount of short-term lease cost, including expense for lease with term of one month or less. Variable lease cost Variable Lease, Cost Sublease income Sublease Income Total net lease cost Lease Cost Net of Sublease Income Amount of lease cost, net of sublease income, recognized by lessee for lease contract Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Axis] Operating Loss Carryforward Period [Domain] 2020 [Member] Loss Carry Forwards Expirations Year One [Member] Loss Carry Forwards Expirations Year One Member 2021 [Member] Loss Carry Forwards Expirations Year Two [Member] Loss Carry Forwards Expirations Year Two [Member] 2022 [Member] Loss Carry Forwards Expirations Year Three [Member] Loss Carry Forwards Expirations Year Three Member 2023 [Member] Loss Carry Forwards Expirations Year Four [Member] Loss Carry Forwards Expirations Year Four Member 2024 [Member] Loss Carry Forwards Expirations Year Five [Member] Loss Carry Forwards Expirations Year Five Member 2025 and after [Member] Loss Carry Forwards Expirations After Year Five [Member] Loss Carry Forwards Expirations After Year Five Member Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Income tax loss carryforwards to be fully utilized Schedule of Income Before Income Taxes, Domestic and Foreign Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Schedule of Provision for (Benefit from) Income Taxes on Income Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Income Tax Loss Carryforwards Summary of Operating Loss Carryforwards [Table Text Block] Schedule of Changes in Deferred Tax Valuation Allowance Summary of Valuation Allowance [Table Text Block] Schedule of Unrecognized Tax Benefits Roll Forward Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Investments Investment [Text Block] Statement of Stockholders' Equity [Abstract] Common Stock [Member] Common Stock [Member] Capital in Excess of Par Value [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Treasury Stock [Member] Treasury Stock [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] As of Net income for the year Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Issuance of noncontrolling interest Noncontrolling Interest, Increase from Subsidiary Equity Issuance Net loss attributable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Acquisition of redeemable noncontrolling interest Equity Effect of Acquisition of Redeemable Noncontrolling Interest Equity Effect of Acquisition of Redeemable Noncontrolling Interest Acquisition of noncontrolling interest Noncontrolling Interest, Increase from Business Combination Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Change in redemption value of redeemable noncontrolling interests Noncontrolling Interest, Change in Redemption Value Dividends paid on common stock Dividends, Common Stock Repurchase of Class B common stock Treasury Stock, Value, Acquired, Cost Method Issuance of Class B common stock, net of restricted stock award forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Amortization of unearned stock compensation and stock option expense APIC, Share-based Payment Arrangement, Increase for Cost Recognition Other comprehensive income (loss), net of income taxes Reclassification of stranded tax effects as a result of tax reform Tax Cuts and Jobs Act 2017, Reclassification From Accumulated Other Comprehensive Income To Retained Earnings Amount of reclassification adjustments of stranded tax effects from accumulated other comprehensive income to retained earnings as a result of tax reform. Cumulative effect of accounting change Cumulative Effect of New Accounting Principle in Period of Adoption Other Stockholders' Equity, Other Purchase of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest As of Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] As of Acquisition of redeemable noncontrolling interest Acquisition of Redeemable Noncontrolling Interest The fair value of the creation of a redeemable noncontrolling interest due to the acquisition of less than 100% of an entity. Net income attributable to redeemable noncontrolling interests Temporary Equity, Net Income Change in redemption value of redeemable noncontrolling interests Temporary Equity, Change in Redemption Value Change in temporary equity during the period as a result of a change in the redemption value of redeemable noncontrolling interest. Other Temporary Equity, Other Changes Purchase of redeemable noncontrolling interest Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests As of Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Sale Of KHE Campuses Business [Member] Sale Of KHE Campuses Business [Member] Sale of KHE Campuses business [Member] UK Pathways [Member] UK Pathways [Member] UK Pathways [Member] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] Her Majesty's Revenue and Customs (HMRC) [Member] Her Majesty's Revenue and Customs (HMRC) [Member] Applicable Years [Axis] Applicable Years [Axis] Applicable Years [Axis] Applicable Years [Domain] Applicable Years [Domain] [Domain] for Applicable Years [Axis] 2014 to 2018 [Member] 2014 to 2018 [Member] 2014 to 2018 [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of existing legal claims or proceedings that are likely to have a material effect on the Company's business Loss Contingency, Pending Claims, Number Loss contingency, estimate of possible loss Loss Contingency, Estimate of Possible Loss Loss on Guarantor Lease Obligations Loss on Guarantor Lease Obligations The amount of loss recognized on guarantor lease obligations. Amount Paid Entitled To Recover Amount Paid Entitled To Recover The amount paid the Company believes it is entitled to recover. Loss Contingency, Loss in Period Loss Contingency, Loss in Period Long-term Purchase Commitment, Amount Long-term Purchase Commitment, Amount Statement of Cash Flows [Abstract] Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net Income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, amortization and goodwill and other long-lived asset impairment Depreciation, Depletion, Amortization And Impairment The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets, including write-downs for impairments. Amortization of lease right-of-use asset Operating Lease Right Of Use Asset Amortization Amount of amortization expense attributable to right-of-use asset from operating lease. Net pension benefit, settlement, early retirement and special separation benefit expense Net Periodic Benefit For Defined Benefit Pension Plans Excluding Curtailment The net periodic benefit or expense for defined benefit pension plans excluding curtailment. Net pension benefit, settlement, early retirement and special separation benefit expense Net pension benefit, settlement, early retirement and special separation benefit expense Net Periodic Benefit For Defined Benefit Pension Plans Excluding Early Retirement Program and Special Separation Benefit Expense The net periodic benefit or expense for defined benefit pension plans excluding the early retirement program and special separation benefit expense. (Gain) loss on marketable equity securities and cost method investments, net Unrealized Gain (Loss) on Investments Provision for doubtful trade and other receivables Provision For Doubtful Trade And Other Receivables The amounts of provision for doubtful trade and other receivables. Stock-based compensation expense, net Share-based Payment Arrangement, Noncash Expense Debt extinguishment costs Gain (Loss) on Extinguishment of Debt, before Write off of Debt Issuance Cost Foreign exchange loss (gain) Foreign Currency Transaction Gain (Loss), before Tax Net loss (gain) on sales and disposition of businesses Net Gain Loss On Sales And Disposition of Businesses Gain (loss) from sale or disposal of an organization or integrated set of activities (for example, but not limited to, a partnership or corporation) engaged in providing a product or service in a commercial, industrial, or professional environment. Net (gain) loss on sales or write-downs of an equity affiliate and cost method investments Gain (Loss) on Disposition of Assets Net (gain) loss on sales or write-downs of an equity affiliate and cost method investments Marketable Securities And Cost Method Investments Realized Gain Loss This item represents the net total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting. This item also includes losses recognized for other than temporary impairments (OTTI) of the marketable securities and cost method investments. Gain on sale of an equity affiliate Equity Method Investment, Realized Gain (Loss) on Disposal Equity in (earnings) losses of affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Provision for (benefit from) deferred income taxes Net (gain) loss on sales or write-downs of property, plant and equipment GainLossOnSaleOrWritedownOfPropertyPlantEquipment Amount of gain (loss) on sale, disposal or write-down of property, plant and equipment assets. Change in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable, net Increase (Decrease) in Accounts Receivable Inventories Increase (Decrease) in Inventories Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Deferred revenue Increase (Decrease) in Deferred Revenue Income taxes receivable/payable Increase (Decrease) in Income Taxes Other assets and other liabilities, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Other Other Operating Activities, Cash Flow Statement 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] Investments in certain businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sales of marketable equity securities Proceeds from Sale and Maturity of Marketable Securities Purchases of marketable equity securities Payments to Acquire Marketable Securities Loans to related party and affiliate and advance related to Kaplan University transaction AdvanceRelatedToKaplanUniversityTransactionAndLoansToAffiliateAndRelatParty Payments made for advance related to Kaplan University transaction and loans to affiliate and related party. Investments in equity affiliates, cost method and other investments Payments To Acquire Equity Method Cost Method Investments And Other Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence, cost method investments or other investments, not including marketable equity securities. Loans to related party and affiliate and advance related to Kaplan University transaction Payments to Fund Long-term Loans to Related Parties Net proceeds (payments) from sales of businesses, property, plant and equipment and other assets Net Proceeds From Sale Of Businesses Property Plant And Equipment And Other Assets The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period. Also included is the cash inflow from the sale of long-lived, physical assets and other assets. Return of investment in equity affiliates Proceeds from Equity Method Investment, Distribution, Return of Capital Investments in equity affiliates and cost method investments Payments To Acquire Equity Method And Cost Method Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence or cost method investments. Other 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] Repayments of borrowings and early redemption premium RepaymentsOfLongTermDebtAndDebtExtinguishmentCosts The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer and for cost from early extinguishment of debt, which includes only the premium paid. Issuance of borrowings Proceeds from Issuance of Long-term Debt Net borrowings under revolving credit facility Proceeds from (Repayments of) Lines of Credit Net proceeds from vehicle floor plan payable Proceeds From (Payments Of) Vehicle Floor Plan Payable Net The net cash inflow or cash outflow from proceeds or repayment of the vehicle floor plan payable. Common shares repurchased Payments for Repurchase of Common Stock Dividends paid Payments of Ordinary Dividends Purchase of noncontrolling interest and deferred payment of acquisition Purchase of Noncontrolling Interest and Deferred Payment of Acquisition Cash outflow for purchase of noncontrolling interest and deferred payment of an acquisition. Payments of financing costs Payments of Financing Costs Repayments of bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Issuance of noncontrolling interest Proceeds from Noncontrolling Interests Other Proceeds from (Payments for) Other Financing Activities Payment Of Distribution To Affiliate Payment Of Distribution To Affiliate Cash distribution from the Company to an affiliate. Net Cash Provided by (Used in) Financing Activities Net Cash Provided by (Used in) Financing Activities Effect of Currency Exchange Rate Change Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Net Decrease in Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and Cash Equivalents and Restricted Cash at Beginning of Year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and Cash Equivalents and Restricted Cash at End of Year Supplemental Cash Flow Information Supplemental Cash Flow Information [Abstract] Cash paid during the year for: Cash Paid During The Year For: [Abstract] -- None. No documentation exists for this element. -- Income taxes Income Taxes Paid, Net Interest Interest Paid, Excluding Capitalized Interest, Operating Activities U.S. Federal taxes at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount State and local taxes, net of U.S. Federal tax Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Valuation allowance against tax benefits Stock based compensation Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount U.S. Federal Manufacturing Deduction tax benefits Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount Deferred tax impact of U.S. Federal tax rate reduction to 21%, net of state tax impact Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Amount Deferred tax benefit on unremitted non-U.S. subsidiary earnings related to the Tax Act Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Transition Tax on Accumulated Foreign Earnings, Amount Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Total provision for income tax Income Tax Expense (Benefit) Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] U.S. [Member] UNITED STATES Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Transferred over Time [Member] Transferred over Time [Member] Transferred at Point in Time [Member] Transferred at Point in Time [Member] Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] Long-term Contract with Customer [Member] Long-term Contract with Customer [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Percentage of Revenue Percentage of Revenue from Contract with Customer, Excluding Assessed Tax Percentage of Revenue Recognized During Period from Contract with Customer, Excluding Assessed Tax Minimum Term of Contract Minimum Term of Contract Minimum Term of Contract Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months Revenue Remaining Performance Obligation Percentage of Revenue Expected to be Recognized Over Next 12 Months Deferred revenue recognized in period related to beginning balance Deferred Revenue, Revenue Recognized Contract with Customer, Asset, Net, Noncurrent Contract with Customer, Asset, Net, Noncurrent Accounting Policies [Abstract] Schedule of Prospective Adoption of New Accounting Pronouncements Schedule of Prospective Adoption of New Accounting Pronouncements [Table Text Block] Schedule of New Accounting Pronouncements and Changes in Accounting Principles Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Leases Lessee, Operating Leases [Text Block] Components of Lease Expense Lease, Cost [Table Text Block] Supplemental Cash Flow And Balance Sheet Information Related To Leases Schedule Of Supplemental Cash Flow And Balance Sheet Information Related To Leases [Table Text Block] Schedule Of Supplemental Cash Flow And Balance Sheet Information Related To Leases Maturities of Operating Lease Liabilities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] U.S. fixed income [Member] Fixed Income Securities, US [Member] Investment that provides a return in the form of fixed periodic payments and eventual return of principal at maturity, domiciled in United States of America (US). Defined Benefit Plan Assets Allocation (Percent) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Schedule of Inventories and Contracts in Progress Schedule of Inventory, Current [Table Text Block] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Equity Components [Axis] Foreign Currency Translation Adjustments [Member] Curtailment (Gains) Losses Included in Net Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Other income, net Interest expense Interest Expense Provision for (Benefit from) Income Taxes Net of Tax Reclassifications, before tax Provision for (benefit from) income taxes Reclassifications, net of tax Debt Disclosure [Abstract] Debt [Table] Debt [Table] Schedule of all debt, including both short term and long term. Automotive [Member] Automotive [Member] Automotive [Member] Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis] Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis] Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain] Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain] Securities Subject to Mandatory Redemption [Member] Securities Subject to Mandatory Redemption [Member] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, First Anniversary [Member] Debt Instrument, Redemption, Period One [Member] Debt Instrument, Redemption, Second Anniversary [Member] Debt Instrument, Redemption, Period Two [Member] Debt Instrument, Redemption, Third Anniversary [Member] Debt Instrument, Redemption, Period Three [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Eurodollar [Member] Eurodollar [Member] Fed Funds Effective Rate Overnight Index Swap Rate [Member] Fed Funds Effective Rate Overnight Index Swap Rate [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] 7.25% Unsecured Notes due February 1, 2019 [Member] Seven Point Two Five Percent Unsecured Notes Due February One Two Thousand And Nineteen [Member] Seven Point Two Five Percent Unsecured Notes due February One, Two Thousand and Nineteen [Member] Interest Rate Swap [Member] Interest Rate Swap [Member] Other Indebtedness [Member] Other Indebtedness [Member] Other Indebtedness [Member] 5.75% Unsecured Notes due June 1, 2026 [Member] Five Point Seven Five Percent Unsecured Notes due June 1, 2026 [Member] Five Point Seven Five Percent Unsecured Notes due June 1, 2026 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Five Year Revolving Credit Agreement Dated June 29, 2015 [Member] Five Year Revolving Credit Agreement Dated June Twenty-nine Two Thousand Fifteen [Member] Five-year Revolving Credit Agreement dated June 29, 2015 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Multicurrency $100 million portion of revolver [Member] Multicurrency $100 million portion of revolver [Member] Multicurrency $100 million portion of revolver [Member] USD $200 million portion of revolver [Member] USD $200 million portion of revolver [Member] USD $200 million portion of revolver [Member] Pinnacle Bank Loan & Security Agreement [Member] Pinnacle Bank Loan & Security Agreement [Member] Pinnacle Bank Loan & Security Agreement [Member] Pinnacle Bank Term Loan [Member] Pinnacle Bank Term Loan [Member] Term loan with Pinnacle Bank Pinnacle Bank Line Of Credit [Member] Pinnacle Bank Line Of Credit [Member] Pinnacle Bank line of credit [Member] Commercial note with SunTrust [Member] Commercial note with SunTrust [Member] Commercial Note With SunTrust [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Unamortized debt issuance costs Debt Issuance Costs, Net Line of Credit Long-term Line of Credit Interest rate Debt Instrument, Interest Rate, Stated Percentage Maturity year Debt Instrument, Maturity Date Loans Payable to Bank Loans Payable to Bank Debt Instrument, Term Debt Instrument, Term Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Minimum Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Minimum Minimum consolidated fixed charge coverage ratio based upon the ratio of consolidated as defined in the loan and security agreement. Notes Payable to Bank Notes Payable to Bank Debt Instrument, Periodic Payment, Principal Debt Instrument, Periodic Payment, Principal Derivative, Notional Amount Derivative, Notional Amount Debt instrument, face amount Debt Instrument, Face Amount Redemption of notes outstanding Extinguishment of Debt, Amount Debt extinguishment costs Credit facility current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Applicable interest rate margin Debt Instrument, Basis Spread on Variable Rate Debt Instrument Price Percentage Of Outstanding Balance Redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Debt covenant net leverage ratio, maximum Debt Instrument, Covenant, Net Leverage Ratio, Maximum Maximum net leverage ratio required to be maintained under Credit Agreement. Debt covenant interest coverage ratio, minimum Debt Instrument, Covenant, Interest Coverage Ratio, Minimum Minimum consolidated interest coverage ratio based upon the ratio of consolidated adjusted EBITDA to consolidated interest expense as determined pursuant to the Credit Agreement. Derivative, Fixed Interest Rate Derivative, Fixed Interest Rate Basis Spread on Variable Rate Derivative, Basis Spread on Variable Rate Interest rate swap percentage rate Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate Average borrowings outstanding Average Outstanding Debt Amount Average borrowings outstanding during the period, both short and long term. Weighted average interest rate of borrowings Debt Instrument, Interest Rate During Period Interest expense Interest income Investment Income, Interest Fair value of debt instrument Debt Instrument, Fair Value Disclosure Carrying value of debt instrument Unsecured Debt Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Capital Contributor [Axis] Capital Contributor [Axis] Capital Contributor [Axis] Capital Contributor [Domain] Capital Contributor [Domain] [Domain] for Capital Contributor [Axis] Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Domain] Period of Transition Operations and Support Agreement [Domain] [Domain] for Period of Transition Operations and Support Agreement [Axis] After June 30, 2048 [Member] After June 30, 2048 [Member] Period of time after June 30, 2048 (thirtieth year) for which the TOSA term applies After June 30, 2024 [Member] After June 30, 2024 [Member] Period of time after June 30, 2024 (7th year and beyond) for which the TOSA term applies After June 30, 2023 [Member] After June 30, 2023 [Member] Period of time after June 30, 2023 (6th year and beyond) for which the TOSA term applies After June 30, 2027 [Member] After June 30, 2027 [Member] Period of time after June 30, 2027 for which the TOSA term applies July 1, 2022 through June 30, 2027 [Member] July 1, 2022 through June 30, 2027 [Member] Period of time July 1, 2022 through June 30, 2027 for which the TOSA term applies (Years 5-9) March 22, 2018 through June 30, 2022 [Member] March 22, 2018 through June 30, 2022 [Member] Period of time March 22, 2018 through June 30, 2022 for which the TOSA term applies (first 4 years) March 22, 2018 through June 30, 2023 [Member] March 22, 2018 through June 30, 2023 [Member] Period of time March 22, 2018 through June 30, 2023 for which the TOSA term applies (first 5 years) Recipient of Consideration [Axis] Recipient of Consideration [Axis] Recipient of Consideration Recipient of Consideration [Domain] Recipient of Consideration [Domain] [Domain] for Recipient of Consideration Kaplan [Member] Kaplan [Member] Kaplan [Member] CSI Pharmarcy [Member] CSI Pharmarcy [Member] CSI Pharmarcy [Member] GHC One [Member] GHC One [Member] GHC One [Member] Joyce/Dayton Corp. [Member] Joyce/Dayton Corp. [Member] Joyce/Dayton Corp. [Member] Kaplan Australia [Member] Kaplan Australia [Member] Kaplan Australia [Member] Group Dekko [Member] Group Dekko [Member] Group Dekko [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Auto dealerships [Member] Auto dealerships [Member] Auto dealerships Heverald [Member] Heverald [Member] Heverald [Member] Clyde's Restaurant Group [Member] Clyde's Restaurant Group [Member] Clyde's Restaurant Group CSI Pharmacy Holding Company, LLC [Member] [Member] CSI Pharmacy Holding Company, LLC [Member] [Member] CSI Pharmacy Holding Company, LLC [Member] [Member] Professional Publications, Inc. [Member] Professional Publications, Inc. [Member] Professional Publications, Inc. College for Financial Planning [Member] College for Financial Planning [Member] College for Financial Planning Furnlite Inc [Member] Furnlite Inc [Member] Furnlite Inc [Member] Marketplace Strategy [Member] Marketplace Strategy [Member] Marketplace Strategy [Member] Genesis [Member] Genesis [Member] Genesis [Member] Red Marker [Member] Red Marker [Member] Red Marker [Member] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Hometown Home Health and Hospice [Member] Hometown Home Health and Hospice [Member] Hometown Home Health and Hospice Business Acquisition [Line Items] Business Acquisition [Line Items] Percentage of Contributed Capital Percentage of Contributed Capital Percentage of Contributed Capital Guaranteed Return Guaranteed Return Preferred annual return on portfolio investments guaranteed to the Company Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Percentage of Distributions Available to Common Unit Holders Percentage of Distributions Available to Common Unit Holders Percentage of distributions available to common unit holders Number of businesses acquired Number of Businesses Acquired Cost of acquisition Business Combination, Consideration Transferred Floor plan payable Vehicle Floor Plan Facility Payable The amount borrowed to finance the purchase of specific vehicle inventories. Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition Percentage of interest acquired Business Acquisition, Percentage of Voting Interests Acquired Management Fee Management Fee Management fee payable by the Company in connection with management services provided under the management services agreement Percentage of Shares Eligible to be Redeemed Percentage of Shares Eligible to be Redeemed Percentage of share minority shareholders may put to the Company through redeemable noncontrolling interest Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest, Equity, Other, Fair Value Advance to Minority Shareholder Advance to Minority Shareholder Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Pension and other post retirement benefits liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension and Other Post Retirement Benefits Liabilities Amount of pension and postretirement liabilities assumed at the acquisition date. Payments to Acquire Businesses, Net of Cash Acquired Fair value of redeemable noncontrolling interest acquired Business Combination Acquisition Of Less than 100 Percent Redeemable Noncontrolling Interest Fair Value This element represents the fair value of the redeemable noncontrolling interest in the acquiree at the acquisition date. Acquisition-related costs Business Acquisition, Transaction Costs Goodwill expected to be deductible for income tax purposes Business Acquisition, Goodwill, Expected Tax Deductible Amount Revenues of acquired companies since acquisition date Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Operating loss of acquired companies since acquisition date Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Renewal Periods Transition and Operations Support Agreement Renewal Periods Transition and Operations Support Agreement Renewal Periods after initial 30 year term Gain on Disposition of Business Gain (Loss) on Disposition of Business Gain Related to Contingent Consideration Gain Related to Contingent Consideration Contingent consideration gain related to the sale of a business. Percentage of Cost Efficiencies Percentage of Cost Efficiencies Percentage of Cost Efficiencies to be used to Calculate Additional Efficiency Payment First Five Years of Transition and Operations Support Agreement First Five Years of Transition and Operations Support Agreement First five years of TOSA Amount of Priority Payment Per Year Beyond Costs Amount of Priority Payment Per Year Beyond Costs Amount of priority payment made to Purdue University Global beyond costs before any payment to Kaplan Kaplan Share of Purdue University Global Revenue Kaplan Share of Purdue University Global Revenue Percentage representing Kaplan's fee based on Purdue University Global Revenue Percentage of Revenue Remaining To Be Paid Percentage of Revenue Remaining To Be Paid Percentage of Purdue University Global Revenue remaining after Kaplan Efficiency Payment and other adjustments paid to Purdue University Global Kaplan University Transaction Termination Fee Kaplan University Transaction Termination Fee Percent of Purdue Global University revenue for preceding 12 month period to be paid to terminate the Transition and Operations Support Agreement Purdue University Global Final Payment Note Duration Purdue University Global Final Payment Note Duration Duration of note for final payment made by Purdue University Global to Kaplan upon termination of TOSA Annual Purdue University Global Cash Operating Losses Annual Purdue University Global Cash Operating Losses Annual Purdue University Global cash operating losses threshold for option to terminate Transition and Operations Support Agreement Aggregate Purdue University Global Cash Operating Losses Aggregate Purdue University Global Cash Operating Losses Aggregate Purdue University Global cash operating losses threshold for option to terminate Transition and Operations Support Agreement Number of Consecutive Years of Purdue University Global Cash Operating Losses Number of Consecutive Years of Purdue University Global Cash Operating Losses Number of consecutive years of Purdue University Global cash operating losses for option to terminate Transition and Operations Support Agreement Number Of Businesses Disposed Number Of Businesses Disposed The number of businesses disposed of by the entity during the period. Noncontrolling Interest, Ownership Percentage by Parent Noncontrolling Interest, Ownership Percentage by Parent Prospective Adoption of New Accounting Pronouncements [Table] Prospective Adoption of New Accounting Pronouncements [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Previous Accounting Guidance [Member] Previous Accounting Guidance [Member] Accounting Standards Update 2016-02 [Member] Accounting Standards Update 2016-02 [Member] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] Previously Reported [Member] Previously Reported [Member] Restatement Adjustment [Member] Restatement Adjustment [Member] Item Effected [Line Items] Item Effected [Line Items] Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Income (Loss) from Continuing Operations before Income Taxes [Abstract] Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest [Abstract] U.S. Income (Loss) from Continuing Operations before Income Taxes, Domestic Non-U.S. Income (Loss) from Continuing Operations before Income Taxes, Foreign Income Before Income Taxes Capital Stock, Stock Awards And Stock Options Capital Stock, Stock Awards And Stock Options [Text Block] -- None. No documentation exists for this element. -- Pro Forma Operating revenues Business Acquisition, Pro Forma Revenue Pro Forma Net income Business Acquisition, Pro Forma Net Income (Loss) Land Land Buildings Buildings and Improvements, Gross Machinery, equipment and fixtures Machinery and Equipment, Gross Leasehold improvements Leasehold Improvements, Gross Construction in progress Construction in Progress, Gross Property, plant and equipment, gross Property, Plant and Equipment, Gross Less accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, plant and equipment, net 2020 Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 2021 Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2022 Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2023 Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2024 Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2025-2029 Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Accelerated depreciation Restructuring and Related Cost, Accelerated Depreciation Severance Severance Costs Other Other Restructuring Costs Total restructuring costs Schedule of Goodwill [Table] Schedule of Goodwill [Table] Other Businesses [Member] Professional (U.S.) [Member] Kaplan Professional [Member] Kaplan Professional [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Goodwill, beginning balance Goodwill, Gross Accumulated impairment losses, beginning balance Goodwill, Impaired, Accumulated Impairment Loss Goodwill, net, beginning balance Measurement period adjustment Goodwill, Purchase Accounting Adjustments Acquisitions Goodwill, Acquired During Period Impairment Goodwill, Impairment Loss Dispositions Goodwill, Written off Related to Sale of Business Unit Foreign currency exchange rate changes Goodwill, Foreign Currency Translation Gain (Loss) Goodwill, ending balance Accumulated impairment losses, ending balance Goodwill, net, ending balance Operating Costs and Expenses Operating Costs and Expenses [Abstract] Operating Operating Expense Generally recurring costs associated with normal operations including the portion of these expenses which can be clearly related to production and included in cost of sales or services. Excludes selling, general and administrative expenses. Selling, general and administrative Selling, General and Administrative Expenses The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. Also includes expenses such as bad debt expense, and gain (loss) on disposition of assets. Amortization of intangible assets Total Operating Costs and Expenses Costs and Expenses Income from Operations Equity in earnings of affiliates, net Interest expense (Loss) gain on marketable equity securities, net Other income (expense), net Provision for Income Taxes Net Loss (Income) Attributable to Noncontrolling Interests Income (Loss) Attributable to Redeemable Noncontrolling Interest and Nonredeemable Noncontrolling Interest Amount of Net Income (Loss) attributable to redeemable noncontrolling interest and nonredeemable noncontrolling interest. Net Income Attributable to Graham Holdings Company Common Stockholders Net Income (Loss) Attributable to Parent Quarterly Comprehensive Income (Loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Per Share Information Attributable to Graham Holdings Company Common Stockholders Earnings Per Share [Abstract] Basic net income per common share (in usd per share) Earnings Per Share, Basic Basic average number of common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted net income per common share (in usd per share) Earnings Per Share, Diluted Diluted average number of common shares outstanding (in shares) Weighted Average Number Of Potentially Dilutive Shares Outstanding The weighted average number of shares outstanding that could potentially dilute basic EPS. Schedule of Quantifying Prior Year Misstatement Corrected in Current Year Financial Statements [Table] Schedule of Quantifying Prior Year Misstatement Corrected in Current Year Financial Statements [Table] Prior Period Adjustments [Axis] Prior Period Adjustments [Axis] -- None. No documentation exists for this element. -- Prior Period Adjustments [Domain] Prior Period Adjustments [Domain] -- None. No documentation exists for this element. -- Periods from Q3 2016 to Q3 2017 [Member] Periods from Q3 2016 to Q3 2017 [Member] Periods from Q3 2016 to Q3 2017 [Member] [Member] Quantifying Misstatement in Current Year Financial Statements [Line Items] Quantifying Misstatement in Current Year Financial Statements [Line Items] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Beginning unrecognized tax benefits Unrecognized Tax Benefits Increases related to current year tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Increases related to prior year tax positions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Decrease related to prior year tax positions Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Decreases related to settlement with tax authorities Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Decreases due to lapse of applicable statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Ending unrecognized tax benefits Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Table] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Table] Disclosures pertaining to an entity's basic and diluted earnings per share. Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Share-based Payment Arrangement, Option [Member] Share-based Payment Arrangement, Option [Member] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items] [Line Items] for Disclosures pertaining to an entity's basic and diluted earnings per share. Net income attributable to Graham Holdings Company common stockholders Less: Dividends paid–common stock outstanding and unvested restricted shares Dividends Paid Common Stock And Share-based Compensation-Cash Amount of paid and unpaid common stock dividends declared with the form of settlement in cash and amount of paid and unpaid cash dividends declared and applicable to holders of share-based compensation, for example, but not limited to, non-vested shares, stock options, or restricted stock units. Undistributed earnings Undistributed Earnings, Basic Percent allocated to common stockholders Percentage Of Undistributed Earnings Allocated To Common Stockholders Represents the percentage allocation of undistributed earnings to common stockholders. Undistributed earnings allocated to common stockholders Undistributed Earnings Allocated To Common Stockholders The earnings that is allocated to common stock to the extend that each stockholder may share in the earnings as if all the earnings for the period has been distributed. Add: Dividends paid–common stock outstanding Dividends, Common Stock, Cash Numerator for basic earnings per share Net Income (Loss) Available to Common Stockholders, Basic Add: Additional undistributed earnings due to dilutive stock options Additional Undistributed Earnings Due To Dilutive Stock Options The earnings that is allocated to common stock due to the dilutive effect of stock options in diluted earnings per share. Numerator for diluted earnings per share Net Income (Loss) Available to Common Stockholders, Diluted Add: Effect of dilutive stock options (shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Denominator for diluted earnings per share (shares) Weighted Average Number of Shares Outstanding, Diluted Income Per Share From Continuing Operations To Common Stockholders [Abstract] Income Per Share From Continuing Operations To Common Stockholders [Abstract] Income Per Share From Continuing Operations To Common Shareholders. Earnings Per Share, Diluted (in usd per share) Share-based Payment Arrangement, Option [Member] Common Class B [Member] Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Beginning, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Exercised, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Expired or forfeited, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period End, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Beginning, Average Option Price (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted, Average Option Price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Exercised, Average Option Price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Expired or forfeited, Average Option Price (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price End, Average Option Price (in dollars per share) Acquisitions and Dispositions of Businesses Mergers, Acquisitions and Dispositions Disclosures [Text Block] Exercise Price Range [Axis] Exercise Price Range [Axis] Exercise Price Range [Domain] Exercise Price Range [Domain] Exercise Price Above Fair Market Value Of Common Stock [Member] Exercise Price Above Fair Market Value Of Common Stock [Member] -- None. No documentation exists for this element. -- Kaplan Restricted Stock [Member] Kaplan Restricted Stock [Member] -- None. No documentation exists for this element. -- Kaplan Stock Option [Member] Kaplan Stock Option [Member] -- None. No documentation exists for this element. -- Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2003 Employee Stock Option Plan [Member] 2003 Employee Stock Option Plan [Member] 2003 Employee Stock Option Plan reserves shares of the Company's Class B common stock for options to be granted under the plan. [Member] 2012 Incentive Compensation Plan [Member] 2012 Incentive Compensation Plan [Member] 2012 Incentive Compensation Plan which authorizes the awarding of Class B common stock to key employees in the form of stock awards, stock options and other awards involving the actual transfer of shares. [Member] Dividends [Axis] Dividends [Axis] Dividends [Domain] Dividends [Domain] Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits, by Title of Individual [Axis] Title of Individual [Axis] Title of Individual with Relationship to Entity [Domain] Title of Individual [Domain] Senior Manager [Member] Senior Manager [Member] Senior Manager Restricted Stock [Member] Restricted Stock [Member] Kaplan Stock Option and Restricted Stock [Member] Kaplan Stock Option and Restricted Stock [Member] Kaplan Stock Option and Restricted Stock [Member] Share-based Payment Arrangement [Member] Share-based Payment Arrangement [Member] 2017 Options Granted [Member] 2017 Options Granted [Member] 2017 Options Granted [Member] Right to elect Board of Directors percentage Right To Elect Board Of Directors Percentage Right To Elect Board Of Directors Percentage Shares repurchased by company Treasury Stock, Shares, Acquired Cost of shares repurchased by company Number of shares authorized to be repurchased Stock Repurchase Program, Number of Shares Authorized to be Repurchased Number of shares authorized to be repurchased remaining under previous authorization StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchasedUnderPreviousAuthorization Number of shares authorized to be repurchased remaining under previous authorization. Authorized shares remaining for repurchase Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased Shares reserved for stock awards granted under the plan Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Shares reserved for issuance Common Stock, Capital Shares Reserved for Future Issuance Shares subject to award outstanding Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Shares available for future awards Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Number of shares forfeited due to modification Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Incremental stock compensation expense, net of forfeitures, due to modification Share-based Payment Arrangement, Plan Modification, Incremental Cost Share awards outstanding, restriction will lapse in 2020 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year One Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year One Share awards outstanding, restriction will lapse in 2021 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Two Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Two Share awards outstanding, restriction will lapse in 2023 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Three Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Three Number of shares awarded in 2019 Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Stock-based compensation expense Share-based Payment Arrangement, Expense Total unrecognized compensation expense Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Years over which cost expected to be recognized Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Number of stock options forfeited due to modification Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Options outstanding exercisable now Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Now Options outstanding exercisable now. Options outstanding exercisable in 2020 Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year One Options outstanding exercisable in year one. Options outstanding exercisable in 2021 Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Two Options outstanding exercisable in year two. Options outstanding exercisable in 2022 Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Three Options outstanding exercisable in year three. Options outstanding exercisable in 2023 Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Four Options outstanding exercisable in year four. Options outstanding exercisable in 2024 Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Five Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Five Intrinsic value of options outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Intrinsic value of options exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Intrinsic value of options unvested Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Intrinsic Value Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Intrinsic Value Market value of company's stock Common Stock Stated Market Value Per Share Common Stock Stated Market Value Per Share Options unvested, shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares Options unvested, average exercise price Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Nonvested Weighted Average Exercise Price The weighted average price as of the end of the year at which grantees can acquire the shares reserved for issuance under the stock option plan which are not vested. Options unvested, weighted average remaining contractual term, years Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Nonvested Weighted Average Remaining Contractual Term The weighted average period between the balance sheet date and expiration for all awards outstanding but not vested under the plan, which may be expressed in a decimal value for number of years. Exercised, Number of Shares Intrinsic value of options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Tax benefit from stock option exercises Share-based Payment Arrangement, Exercise of Option, Tax Benefit Number of shares granted Weighted average fair value, granted options Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Fair value of company common stock Fair Value Of Company Common Stock Fair value of company common stock Stock options outstanding Accrual balance related to stock based compensation Deferred Compensation Share-based Arrangements, Liability, Current and Noncurrent Stock compensation payouts Deferred Compensation Arrangement with Individual, Distribution Paid Shares excluded from earnings per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Dividends declared per common share Common Stock, Dividends, Per Share, Declared Conversion of Class A shares to Class B Conversion of Stock, Shares Converted Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Accounting Standards Update 2016-01 [Member] Accounting Standards Update 2016-01 [Member] Accounting Standards Update 2014-09 [Member] Accounting Standards Update 2014-09 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Total lease liabilities Operating Lease, Liability Income Tax Expense (Benefit), Continuing Operations [Abstract] Income Tax Expense (Benefit), Continuing Operations [Abstract] U.S. Federal, Current Current Federal Tax Expense (Benefit) State and Local, Current Current State and Local Tax Expense (Benefit) Non-U.S., Current Current Foreign Tax Expense (Benefit) Total income tax, Current Current Income Tax Expense (Benefit) U.S. Federal, Deferred Deferred Federal Income Tax Expense (Benefit) State and Local, Deferred Deferred State and Local Income Tax Expense (Benefit) Non-U.S., Deferred Deferred Foreign Income Tax Expense (Benefit) Total income tax, Deferred U.S. Federal, Total Federal Income Tax Expense (Benefit), Continuing Operations State and Local, Total State and Local Income Tax Expense (Benefit), Continuing Operations Non-U.S., Total Foreign Income Tax Expense (Benefit), Continuing Operations Schedule of Investments [Table] Schedule of Investments [Table] KIHL [Member] KIHL [Member] KIHL [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Markel Corporation [Member] MarkelCorporation [Member] Markel Corporation [Member] Intersection [Member] Intersection [Member] Intersection Holdings,LLC [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential And Michigan Hospital Joint Venture [Member] Residential And Michigan Hospital Joint Venture [Member] Residential and a Michigan hospital joint venture [Member] Celtic Healthcare Allegheny Health Network Joint Venture [Member] CelticHealthcareAlleghenyHealthNetworkJointVenture [Member] A joint venture formed between Celtic Healthcare and Allegheny Health Network Gimlet Media [Member] Gimlet Media [Member] Gimlet Media [Member] Two investments [Member] Two investments [Member] Two investments [Member] York Joint Venture [Member] York Joint Venture [Member] York Joint Venture [Member] HomeHero [Member] HomeHero [Member] HomeHero [Member] One Investment [Member] One Investment [Member] One Investment [Member] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Money market investments Money Market Funds, at Carrying Value Number of shares held in investment Number Of Shares Held In Investment The number of shares held in an investment. Cash paid for new marketable equity securities Marketable equity securities purchased Available For Sale Securities Equity Acquired Equity securities classified as available-for-sale securities acquired. Cumulative realized gain (loss) on marketable securities Marketable Securities, Realized Gain (Loss) Gain on sales of marketable equity securities Marketable Securities, Realized Gain (Loss), Excluding Other-than-temporary Impairment Loss Ownership percentage of investment in affiliate Equity Method Investment, Ownership Percentage Revenue from Related Parties Revenue from Related Parties Cumulative undistributed income in investments in affiliates Retained Earnings, Undistributed Earnings from Equity Method Investees Gain on sale of an equity affiliate Proceeds from Sale of Equity Method Investments Proceeds from Sale of Equity Method Investments Loan commitment to affiliate Other Commitment Advances to Affiliate Advances to Affiliate Payments to Fund Long-term Loans to Related Parties Loan Receivable, Payment Term Loan Receivable, Payment Terms Description of the payment terms of the debt instrument (for example whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment. Loan Receivable Fixed Interest Rate Related Party Transaction, Rate Equity Method Investment, Other than Temporary Impairment Equity Method Investment, Other than Temporary Impairment Equity Securities without Readily Determinable Fair Value, Amount Equity Securities without Readily Determinable Fair Value, Amount Impairment loss on cost method investments Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount Future minimum lease payments for 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months Future minimum lease payments for 2020 Operating Leases, Future Minimum Payments, Due in Two Years Future minimum lease payments for 2021 Operating Leases, Future Minimum Payments, Due in Three Years Future minimum lease payments for 2022 Operating Leases, Future Minimum Payments, Due in Four Years Future minimum lease payments for 2023 Operating Leases, Future Minimum Payments, Due in Five Years Future minimum lease payments after 2023 Operating Leases, Future Minimum Payments, Due Thereafter Operating leases, future minimum payments due, total Operating Leases, Future Minimum Payments Due Summary of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Defined Benefit Plans Disclosures Defined Benefit Plans Assumption [Axis] Defined Benefit Plans Disclosures Defined Benefit Plans Assumption [Axis] Reflects the description and required disclosures pertaining to the entity's defined benefits pension, by plan or groupings of similar plans. Defined Benefit Plans Disclosures Defined Benefit Plans Assumption [Domain] Defined Benefit Plans Disclosures Defined Benefit Plans Assumption [Domain] Defined Benefit Plans Disclosures Defined Benefit Plans Assumption [Domain] Benefit Obligation [Member] Benefit Obligation [Member] Benefit obligation assumptions. Periodic Cost [Member] Periodic Cost [Member] Periodic cost assumptions. Discount rate (percent) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Rate of compensation increase (percent) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate Ultimate cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Ultimate Weighted-Average Interest Crediting Rate Ultimate weighted-average interest crediting rate used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate. Year that reaches ultimate cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Year Weighted-Average Interest Crediting Rate Reaches Ultimate Rate Year ultimate weighted-average interest crediting rate is expected to be reached, in CCYY format. Rate of compensation increase (percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Series of Individually Immaterial Business Acquisitions [Member] Series of Individually Immaterial Business Acquisitions [Member] Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Inventory Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Lease right-of-use assets Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Right-of-Use Asset Amount of lease right of use assets assumed in business combination Goodwill Indefinite-lived intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets Amortized intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets Amount of other assets acquired at the acquisition date. Floor plan payables Pension and other post retirement benefits liabilities Other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Deferred income taxes Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Current and noncurrent lease liabilities Business Combination, Recognized Identifiable Asset Acquired and Liabiity Assumed, Current and Noncurrent Lease Liabilities Amount of current and noncurrent lease liabilities assumed in business combination Redeemable noncontrolling interest Noncontrolling interest Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value Aggregate purchase price, net of cash acquired Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest, Net Of Cash Received Amount recognized as of the acquisition date for the assets, including goodwill, in excess of (less than) the aggregate liabilities assumed, less the noncontrolling interest in the acquiree, net of cash received. 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] Machinery and Equipment [Member] Machinery and Equipment [Member] Building [Member] Building [Member] Health Care [Member] Health Care [Member] Revenue Source [Axis] Revenue Source [Axis] Revenue Source [Axis} Revenue Source [Domain] Revenue Source [Domain] [Domain] for Revenue Source [Axis} Advertising Revenue [Member] Advertising Revenue [Member] Advertising Revenue [Member] Retransmission Revenue [Member] Retransmission Revenue [Member] Retransmission Revenue [Member] Other Healthcare Services [Member] Other Healthcare Services [Member] Other Healthcare Services [Member] Liquidation Period [Axis] Liquidation Period [Axis] Liquidation Period [Axis] Liquidation Period [Domain] Liquidation Period [Domain] [Domain] for Liquidation Period [Axis] 2026 [Member] 2026 [Member] 2026 [Member] Summary of Significant Accounting Policies [Line Items] Summary of Significant Accounting Policies [Line Items] -- None. No documentation exists for this element. -- Investment maturity length Investment Maturity Length For Classification As Cash And Cash Equivalents Investment maturity length for classification as cash and cash equivalents. Property, Plant and Equipment, Useful Life (in years) Property, Plant and Equipment, Useful Life Amortized Intangible Assets, Useful Life (in years) Number of Performance Obligations Number of Performance Obligations Number of Performance Obligations in standard contract Number of Performance Obligations In Contract With Tuition Cap Number of Performance Obligations In Contract With Tuition Cap Number of Performance Obligations In Contract With Tuition Cap Revenue Recognition, Maximum Period between Recognition of Revenue and Receipt of Payment Revenue Recognition, Maximum Period between Recognition of Revenue and Receipt of Payment Revenue Recognition, Maximum Period between Recognition of Revenue and Receipt of Payment Number of business lines Number of Business Lines The number of business lines. Maximum Term of Contract Maximum Term of Contract Maximum Term of Contract Lessee, Operating Lease, Renewal or Termination Option Term Lessee, Operating Lease, Renewal or Termination Option Term Term of lessee's option to renew or terminate an operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Finance Lease, Right-of-Use Asset Finance Lease, Right-of-Use Asset Finance Lease, Liability, Current Finance Lease, Liability, Current Share-based Payment Arrangement, Option, Exercise Price Range [Table] Share-based Payment Arrangement, Option, Exercise Price Range [Table] Exercise Price $244 [Member] Price Range One [Member] Exercise Price Range of $244-276 Exercise Price $325 [Member] Price Range Two [Member] Exercise Price of $325 Exercise Price $719 [Member] Price Range Three [Member] Exercise Price of $719 Exercise Price Range of $805-$872 [Member] Price Range Four [Member] Exercise Price of $805-872 Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] Low Exercise Price Range High Exercise Price Range Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit Options Outstanding, Shares Outstanding Options Outstanding, Weighted Average Remaining Contractual Life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options Outstanding, Weighted Average Exercise Price (in dollars per share) Options Exercisable, Shares Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options Exercisable, Weighted Average Remaining Contractual Life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Options Exercisable, Weighted Average Exercise Price (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Inventories, Contracts in Progress and Vehicle Floor Plan Payable Inventory Disclosure [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Beginning of year, unvested, Number of Shares Awarded, Number of Shares Vested, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited, Number of Shares End of year, unvested, Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Beginning of year, Average Grant-Date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Awarded, Average Grant-Date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested, Average Grant-Date Fair Value (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 Forfeited, Average Grant-Date Fair Value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value End of year, Average Grant-Date Fair Value (in dollars per share) Investments in Marketable Equity Securities Marketable Securities [Table Text Block] Gain (loss) on marketable equity securities Gain (Loss) on Securities [Table Text Block] Accounts Receivable Accounts Payable And Accrued Liabilities [Abstract] -- None. No documentation exists for this element. -- Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Schedule of Changes in Allowance for Doubtful Accounts Schedule Of Changes In Allowance For Doubtful Accounts And Returns Allowance For Advertising Rate Adjustments And Discounts [Table Text Block] Tabular disclosure of Changes in Allowance for Doubtful Accounts and Returns Allowance for Advertising Rate Adjustments and Discounts Schedule of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Deferred Tax Valuation Allowance [Member] SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] Valuation Allowance [Line Items] Valuation Allowance [Line Items] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Balance at Beginning of Period SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Tax Expense and Revaluation Valuation Allowances And Reserves, Charged To Cost And Expense And Other Charges Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, charged to costs and expenses and other charges. Deductions SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Balance at End of Period Basis of Presentation and Principles of Consolidation Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Reclassifications Reclassification, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Business Combinations Business Combinations and Other Purchase of Business Transactions, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Unrestricted Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Allowance for Doubtful Accounts Accounts Receivable [Policy Text Block] Investments in Equity Securities Investment, Policy [Policy Text Block] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Inventories and Contracts in Progress Inventory, Policy [Policy Text Block] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Evaluation of Long-Lived Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Goodwill and Other Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Investments in Affiliates Equity Method Investments [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Leases Lessee, Leases [Policy Text Block] Pensions and Other Postretirement Benefits Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Self-Insurance Self Insurance Reserve [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Equity-Based Compensation Share-based Payment Arrangement [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Mandatorily Redeemable Noncontrolling Interest Mandatorily Redeemable Noncontrolling Interest [Policy Text Block] Mandatorily Redeemable Noncontrolling Interest [Policy Text Block] Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Recently Adopted and Issued Accounting Pronouncemets New Accounting Pronouncements, Policy [Policy Text Block] Contingencies and Other Commitments Commitments and Contingencies Disclosure [Text Block] Investment Managers [Axis] Investment Managers [Axis] Investment Managers [Axis] Investment Managers [Domain] Investment Managers [Domain] [Domain] for Investment Managers [Axis] Investment Manager 1 [Member] Investment Manager 1 [Member] Investment Manager 1 [Member] Investment Manager 2 [Member] Investment Manager 2 [Member] Investment Manager 2 [Member] Early Retirment Program Expense [Axis] Early Retirment Program Expense [Axis] -- None. No documentation exists for this element. -- Early Retirement Program Expense [Domain] Early Retirement Program Expense [Domain] -- None. No documentation exists for this element. -- Separation Incentive Program [Member] Separation Incentive Program [Member] Separation Incentive Program [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Defined Benefit Plan Assets Total [Member] Defined Benefit Plan Assets Total [Member] -- None. No documentation exists for this element. -- Concentration Risk by Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Geographic Concentration [Member] Geographic Concentration Risk [Member] Single Equity Concentration [Member] Single Equity Concentration [Member] Information about an entity's defined benefit plan's significant investment concentrations in either a single entity, type of industry, foreign country and/or individual fund. Foreign Investments [Member] Foreign Investments [Member] Information about the entity's defined pension plan foreign investments. Fixed income securities [Member] Equity securities [Member] Equity Securities [Member] Equity funds [Member] Equity Funds [Member] Alphabet And Berkshire Hathaway Common Stock [Member] Alphabet And Berkshire Hathaway Common Stock [Member] Alphabet and Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Forney [Member] Forney [Member] Forney [Member] Defined Benefit Plan Health Care Cost Trend Groups [Axis] Defined Benefit Plan Health Care Cost Trend Groups [Axis] Defined Benefit Plan Health Care Cost Trend Groups [Axis] Defined Benefit Plan Health Care Cost Trend Groups [Domain] Defined Benefit Plan Health Care Cost Trend Groups [Domain] Defined Benefit Plan Health Care Cost Trend Groups [Domain] Pre-Age 65 [Member] Pre-Age 65 [Member] Pre-Age 65 [Member] Post-Age 65 [Member] Post Age 65 [Member] Post Age 65 [Member] Medicare Advantage [Member] Medicare Advantage [Member] Medicare Advantage [Member] Multiemployer Plan Type [Axis] Multiemployer Plan Type [Axis] Multiemployer Plans Type [Domain] Multiemployer Plans Type [Domain] Multiemployer Pension Plans [Member] Multiemployer Plans, Pension [Member] Transaction Type [Axis] Transaction Type [Axis] Transaction [Domain] Transaction [Domain] Irrevocable Group Annuity Contract Purchase [Member] Irrevocable Group Annuity Contract Purchase [Member] Irrevocable Group Annuity Contract Purchase [Member] Retirement Benefits Disclosure [Line Items] Retirement Benefits Disclosure [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Payment for settlement Defined Benefit Plan, Benefit Obligation, Payment for Settlement Settlement of obligation Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement Number of retirees and beneficiaries Defined Benefit Plan, Settlement, Number of Retirees And Beneficiaries The amount of retirees and beneficiaries impacted by the purchase of an irrevocable group annuity contract. Settlement Early retirement and special separation benefit program expense Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Company contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Estimated employer contributions in next fiscal year Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Net Periodic Cost (Benefit) for the Year Curtailment Percent of Plan Assets Managed Internally by Company Percent of Plan Assets Managed Internally by Company The percentage of plan assets managed internally by the Company. Percent Of Plan Assets Managed By Investment Companies Percent Of Plan Assets Managed By Investment Companies The percentage of plan assets managed by investment companies. Number of investment companies actively managing plan assets Number Of Investment Companies Managing Plan Assets The number of investment companies actively managing plan assets. Defined benefit plan, target allocation maximum percentage of assets, singular equity security, without prior approval by plan administrator Defined Benefit Plan Target Allocation Percentage Of Assets Singular Equity Security Limit Without Approval Of Plan Administrator Target allocation maximum percentage of investment in a single equity security to total plan assets without prior approval of plan administrator. Defined benefit plan, target allocation percentage of assets Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Minimum percentage of plan assets considered as significant concentrations in pension plans Concentration Risk, Percentage Number of investments the company's pension plan held which individually exceed 10% of total plan assets Number Of Investments Companys Pension Plan Held Which Individually Exceed 10 Percent Of Total Plan Assets Number Of Investments The Companys Pension Plan Held Which Individually Exceed 10 Percent Of Total Plan Assets Value of investments Investments Percentage of total plan assets Discount rate to determine benefit obligation Assumed health care cost trend rate Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Assumed health care cost trend rate, 2021 Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Year Two Assumed rate, for fiscal year two, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status. Direction of change for assumed health care cost trend rate Defined Benefit Plan, Assumed Health Care Cost Trend Rate, Description Ultimate health care cost trend rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Year that rate reaches ultimate trend rate Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate Discount rate to determine periodic cost Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Number of multiemployer plans contributed to Number Of Multiemployer Plans Contributed To Number of multiemployer pension plans to which the Company contributed. Contributions to multiemployer pension plans Multiemployer Plan, Contributions by Employer Expense associated with the retirement benefits provided under incentive savings plans Defined Contribution Plan, Cost Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] Accounts Receivable Accounts Payable And Accrued Liabilities Accounts Receivable Accounts Payable And Accrued Liabilities [Text Block] The entire disclosure of Accounts Receivable Accounts Payable And Accrued Liabilities Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Interest Costs Capitalized Interest Costs Capitalized Property plant and equipment impairment charges Tangible Asset Impairment Charges Defined Benefit Plans [Member] Defined Benefit Plans [Member] Defined benefit plans consisting of various pension plans and a Supplemental Executive Retirement Plan (SERP). Schedule of Obligation, Asset and Funding Information Schedule of Net Funded Status [Table Text Block] Schedule of Amounts Recognized in Balance Sheet Schedule of Amounts Recognized in Balance Sheet [Table Text Block] Schedule of Assumptions Used Defined Benefit Plan, Assumptions [Table Text Block] Schedule of Estimated Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Schedule of Net (Benefit) Costs Schedule of Net Benefit Costs [Table Text Block] Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Loss) Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Allocation of the Assets of the Company's Pension Plans Schedule of Allocation of Plan Assets [Table Text Block] Fair Value, Assets Measured on Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block] Loss on guarantor obligations Net gain on cost method investments Net (loss) gain on sales of businesses Foreign currency (loss) gain, net Gain on sale of cost method investments Cost-method Investments, Realized Gain (Loss) Impairment of cost method investments Impairment of cost method investments Cost-method Investments, Other than Temporary Impairment Net (loss) gain on sale of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment Marketable Securities, Realized Gain (Loss) Other, net Other Nonoperating Gains (Losses) Other income, net Discount rate (percent) Expected return on plan assets (percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate Ultimate cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Ultimate Weighted-Average Interest Crediting Rate Ultimate weighted-average interest crediting rate used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate. Year that reaches ultimate cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Year that Weighted-Average Interest Crediting Rate Reaches Ultimate Rate Year ultimate weighted-average interest crediting rate is expected to be reached, in CCYY format. Pensions and Other Postretirement Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Impairment of intangible assets Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Number of stations that recorded impairment of intangible assets Number Of Stations Recorded Impairment Of Intangible Assets The number of stations that recorded impairment of intangible assets. Gain (loss) on marketable equity securities, net Less: Net (gains) losses in earnings from marketable equity securities sold Equity Securities, FV-NI, Realized Gain (Loss) Net unrealized gains (losses) in earnings from marketable equity securities still held at the end of the year Equity Securities, FV-NI, Unrealized Gain (Loss) Components of Debt Schedule of Long-term Debt Instruments [Table Text Block] Antidilutive Restricted Stock Antidilutive Restricted Stock Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of restricted stock using the treasury stock method. Income Statement [Abstract] Total Operating Costs and Expenses Income from Operations Net Income Net Income Attributable to Noncontrolling Interests Net Income Attributable to Graham Holdings Company Common Stockholders Schedule of Restructuring Costs Restructuring and Related Costs [Table Text Block] Summary of Segment Reporting Information, by Operating Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] Unrealized Gain (Loss) on Pensions and Other Postretirement Plans [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] Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance Reclassification From Accumulated Other Comprehensive Income To Retained Earnings Reclassification from accumulated other comprehensive income to retained earnings Other comprehensive (loss) income before reclassifications Net amount reclassified from accumulated other comprehensive income Other Comprehensive Income (Loss), Net of Tax Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Operating cash flows from operating leases (payments) Operating Lease, Payments Right-of-use assets obtained in exchange for operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Lease right-of-use assets Current lease liabilities Noncurrent lease liabilities Operating Lease, Liability Operating lease, weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Operating lease, weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Debt Debt Disclosure [Text Block] Goodwill, Impairment Loss Goodwill and Intangible Asset Impairment Goodwill and Intangible Asset Impairment Unrecognized actuarial (gain) loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Unrecognized prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Gross amount Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Deferred tax liability (asset) Defined Benefit Plan Accumulated Other Comprehensive Income Tax Tax recorded on the defined benefit plan accumulated other comprehensive income. Net amount Allowance for doubtful accounts[Member] SEC Schedule, 12-09, Allowance, Credit Loss [Member] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] Additions - Charged to Costs and Expenses SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Accounts Receivable, after Allowance for Credit Loss [Abstract] Accounts Receivable, after Allowance for Credit Loss [Abstract] Receivables from contracts with customers, less doubtful accounts Accounts Receivable, after Allowance for Credit Loss, Current Other receivables Other Receivables Accounts receivable, net Accounts Receivable, Allowance for Credit Loss Accounts Receivable, Allowance for Credit Loss Accounts Payable, Current [Abstract] Accounts Payable, Current [Abstract] Accounts payable and accrued liabilities Accounts Payable and Other Accrued Liabilities, Current Accrued compensation and related benefits Employee-related Liabilities, Current Total accounts payable and accrued liabilities Business Segments Segment Reporting Disclosure [Text Block] Cover page. Document Type Document Type Document Annual Report Document Annual Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Documents Incorporated by Reference [Text Block] Documents Incorporated by Reference [Text Block] Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Central Index Key Entity Central Index Key Impairment of intangible assets Impairment of Intangible Assets, Finite-lived Impairment of intangible and other long-lived assets Impairment Of Intangible And Other Long-Lived Assets The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of intangible and other long-lived assets. Amortization of Intangible Assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Estimated amortization of intangible assets, 2020 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Estimated amortization of intangible assets, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Two Estimated amortization of intangible assets, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Three Estimated amortization of intangible assets, 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Four Estimated amortization of intangible assets, 2024 Finite-Lived Intangible Assets, Amortization Expense, Year Five Estimated amortization of intangible assets, after 2024 Finite-Lived Intangible Assets, Amortization Expense, after Year Five Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Unsecured notes Other indebtedness Other Long-term Debt Total Debt Debt, Long-term and Short-term, Combined Amount Less: current portion Total Long-Term Debt Deferred Income Tax Liabilities [Table] Deferred Income Tax Liabilities [Table] Deferred Income Tax Liabilities [Table] Deferred Income Tax Liabilities [Line Items] Deferred Income Tax Liabilities [Line Items] [Line Items] for Deferred Income Tax Liabilities [Table] Employee benefit obligations Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Accounts receivable Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts State income tax loss carryforwards Capital loss carryforwards U.S. Federal income tax loss carryforwards U.S Federal foreign income tax credit carryforwards Non-U.S. income tax loss carryforwards Leases Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Deferred Rent Other Deferred Tax Assets, Tax Deferred Expense, Other Deferred tax assets Deferred Tax Assets, Gross Valuation allowance Deferred tax assets, net Deferred Tax Assets, Net of Valuation Allowance Prepaid pension cost Deferred Tax Liabilities, Prepaid Expenses Unrealized gain on available-for-sale securities Deferred Tax Liabilities, Unrealized Gains on Available-for-sale Securities Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains on available-for-sale securities. Goodwill and other intangible assets Deferred Tax Liabilities, Goodwill and Intangible Assets Property, plant and equipment Deferred Tax Liabilities, Property, Plant and Equipment Leases Deferred Tax Liabilities, Leasing Arrangements Non-U.S. withholding tax Deferred tax liabilities Deferred Tax Liabilities, Gross Deferred Income Tax Liabilities, Net Deferred Tax Liabilities, Net Statement of Comprehensive Income [Abstract] Other Comprehensive Income (Loss), Before Tax Other Comprehensive Income (Loss), before Tax [Abstract] Foreign currency translation adjustments: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent [Abstract] Translation adjustments arising during the year Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Adjustment for sales of businesses with foreign operations Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Total foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Unrealized gains on available-for-sale securities: Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax [Abstract] Unrealized gains for the year Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Pension and other postretirement plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Actuarial gain (loss) Prior service (cost) credit Amortization of net actuarial gain included in net income Amortization of net prior service (credit) cost included in net income Curtailments and settlements included in net income Total pension and other postretirement plans Cash flow hedges (loss) gain Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Cash flow hedges (loss) gain Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax Other Comprehensive Income (Loss), Before Tax Income tax (expense) benefit related to items of other comprehensive income (loss) Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Total Comprehensive Income Attributable to Graham Holdings Company Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward] Fair value of assets at beginning of year Purchases, sales and settlements, net Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Purchase, Sale, and Settlement Gains relating to assets sold Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Sold (Losses) gains relating to assets still held at year-end Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held Fair value of assets at end of year Inventory, Current [Table] Inventory, Current [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Inventory [Axis] Inventory [Axis] Inventory [Domain] Inventory [Domain] Inventory [Line Items] Inventory [Line Items] Weighted average interest rate Borrowing capacity Vehicle Floor Plan Facility Borrowing Capacity The aggregate borrowing capacity under the vehicle floor plan facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facilities. Vehicle floor plan payable Floor plan assistance Vehicle Floor Plan Facility Assistance The amount of assistance received from the manufacturers recognized as a reduction of operating expenses. Cash overdrafts Bank Overdrafts Prepaid Expense, Current Prepaid Expense, Current Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Benefit obligation at begining of year Defined Benefit Plan, Benefit Obligation Amendments Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Actuarial (gain) loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Acquisitions Defined Benefit Plan, Benefit Obligation, Business Combination Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Special termination benefits Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits Curtailment Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment Benefits paid, net of Medicare subsidy Defined Benefit Plan Benefits Paid Net The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. This amount is net of Medicary subsidies. Settlement Benefit obligation at end of year Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Employer contributions Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Benefits paid, net of Medicare subsidy Settlement Defined Benefit Plan, Plan Assets, Payment for Settlement Funded status Defined Benefit Plan, Funded (Unfunded) Status of Plan Preferred Stock, par value per share Preferred Stock, Par or Stated Value Per Share Preferred Stock, shares authorized Preferred Stock, Shares Authorized Preferred Stock, shares issued Preferred Stock, Shares Issued Common Stock, par value 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 Treasury Stock, Shares Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Other current investments Other Short-term Investments Interest rate swap Interest Rate Cash Flow Hedge Asset at Fair Value Total Financial Assets Investments, Fair Value Disclosure Liabilities Liabilities [Abstract] Deferred compensation plan liabilities Deferred Compensation Liability, Current and Noncurrent Interest rate swap Interest Rate Cash Flow Hedge Liability at Fair Value Foreign exchange swap Foreign Currency Contracts, Liability, Fair Value Disclosure Mandatorily redeemable noncontrolling interest Mandatorily Redeemable Noncontrolling Interest Fair Value Disclosure Fair value of the Noncontrolling interest that an entity is required to redeem for cash or other assets at a fixed or determinable date or upon the occurrence of an event. Total Financial Liabilities Financial Liabilities Fair Value Disclosure Summary of Other Non-Operating Income Schedule of Other Nonoperating Income (Expense) [Table Text Block] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Operating lease impairment Operating Lease, Impairment Loss Lease cost net of sublease income Lessee, operating lease, lease not yet commenced, term of contract Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract Lessee, operating lease, lease not yet commenced, payments due Lessee, Operating Lease, Lease Not yet Commenced, Payments Due Payments due for operating lease arrangements which have not yet commenced as of the date of the balance sheet Future minimum sublease payments due Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals Rent expense for operating leases Operating Leases, Rent Expense Sublease rental income Operating Leases, Income Statement, Sublease Revenue Deferred Revenue Deferred Revenue Deferred Revenue, Period Increase Percentage Deferred Revenue, Period Increase (Decrease) Percentage Deferred Revenue, Period Increase (Decrease) Percentage Quarterly Impact of Certain Items [Table] Quarterly Impact of Certain Items [Table] Quarterly Impact of Certain Items [Table] Quarterly Impact of Certain Items [Line Items] Quarterly Impact of Certain Items [Line Items] Quarterly Impact of Certain Items [Line Items] VAT Provision, After Tax VAT Provision, After Tax VAT Provision, After Tax Earnings per Share, Diluted, VAT Provision Earnings per Share, Diluted, VAT Provision Earnings per Share, Diluted, VAT Provision Reduction to operating expenses in association with spectrum repack agreement Reduction to Operating Expenses In Association With Spectrum Repack Mandate, Net of Tax Reduction to operating expenses in association with spectrum repack mandate, after tax Earnings Per Share, Diluted, Reduction to operating expenses in association with spectrum repack agreement Earnings Per Share, Diluted, Reduction to Operating Expenses in Association with Spectrum Repack Agreement Earnings Per Share, Reduction to operating expenses in association with spectrum repack agreement Impairment of Intangible Assets, After Tax Impairment of Intangible Assets, Net of Tax Impairment of intangible assets, After tax Earnings per Share, Diluted, Impairment Of Intangible Assets Earnings per Share, Diluted, Impairment Of Intangible Assets Earnings per Share, Diluted, Impairment of Intangible Assets Settlement Gain Related to Pension Annuity Purchase, After Tax Settlement Gain Related to Pension Annuity Purchase, After Tax Settlement Gain Related to Pension Annuity Purchase, After Tax Earnings Per Share, Diluted, Settlement gain related to pension annuity purchase Earnings Per Share, Diluted, Settlement gain related to pension annuity purchase Earnings Per Share, Diluted, Settlement gain related to pension annuity purchase Expenses Related to Separation Inventive Plan, After Tax Expenses Related to Separation Inventive Plan, After Tax Expenses Related to Separation Inventive Plan, After Tax Earnings Per Share, Diluted, Expenses Related to Separation Incentive Plan Earnings Per Share, Diluted, Expenses Related to Separation Incentive Plan Earnings Per Share, Diluted, Expenses Related to Separation Incentive Plan Gain (Loss) on Marketable Equity Securities, after tax Gain (Loss) On Marketable Equity Securities, Net of Tax Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income, after tax Earnings per share, diluted, gain (loss) on marketable equity securities Earnings Per Share, Diluted, Losses On Marketable Equity Securities Earnings per share, diluted, losses on marketable equity securities Write-Ups of Cost Method Investments, After Tax Write-Ups of Cost Method Investments, After Tax Write-Ups of Cost Method Investments, After Tax Earnings per Share, Diluted, Write-Ups of Cost Method Investments Earnings per Share, Diluted, Write-Ups of Cost Method Investments Earnings per Share, Diluted, Write-Ups of Cost Method Investments Gain on Sale of Gimlet Media, After Tax Gain on Sale of Gimlet Media, After Tax Gain on Sale of Gimlet Media, After Tax Earnings per Share, Diluted, Gain on Sale of Gimlet Media Earnings per Share, Diluted, Gain on Sale of Gimlet Media Earnings per Share, Diluted, Gain on Sale of Gimlet Media Non-operating unrealized foreign currency gains (losses), after tax Foreign Currency Transaction Gain (Loss), Unrealized, Net of Tax Foreign Currency Transaction Gain (Loss), After Tax Earnings Per Share, Diluted, Foreign Currency Transaction Gain (Loss), Unrealized Earnings Per Share, Diluted, Foreign Currency Transaction Gain (Loss), Unrealized Earnings Per Share, Diluted, Foreign Currency Transaction Gain (Loss), Unrealized Effective Income Tax Rate Reconciliation, Share-Based Compensation, Excess Tax Benefit Earnings Per Share, Diluted, Effective Income Tax Rate Reconciliation, Share-based Compensation Excess Tax Benefit Earnings Per Share, Diluted, Effective Income Tax Rate Reconciliation, Share-based Compensation Excess Tax Benefit Earnings Per Share, Diluted, Effective Income Tax Rate Reconciliation, share-based compensation, excess tax benefit amount Interest Expense, after tax Interest Expense, Net of Tax The amount of interest expense, after tax Earnings per share, diluted, interest expense Earnings Per Share, Diluted, Interest Expense Earnings per share, diluted, interest expense Debt extinguishment costs, after tax Debt Extinguishment Costs, Net of Tax Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity, after tax. Earnings per share, diluted, debt extinguishment costs Earnings Per Share, Diluted, Debt Extinguishment Costs Earnings per share, diluted, debt extinguishment costs Gain on Lump Sum Pension Settlement and curtailment of postretirement benefit plans, after tax Gain On Lump Sum Pension Settlement And Curtailment Of Postretirement Benefit Plans, Net of Tax Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement, after tax. Earnings per share, diluted, settlement gain related to bulk lump sum pension offering and curtailment gain Earnings Per Share, Diluted, Settlement Gain Related To Bulk Lump Sum Pension Offering And Curtailment Gain Earnings per share, diluted, settlement gain related to bulk lump sum pension offering and curtailment gain Non-operating gain from sales, write-ups and impairments of investments, and related to sales of land and businesses, including losses on guarantor obligations Non-Operating Gain From Sales, Write-ups And Impairments Of Investments, And Related To Sales Of Land And Businesses, Including Losses On Guarantor Obligations, Net of Tax Non-operating gain from sales, write-ups and impairments of investments, and related to sales of land and businesses, including losses on guarantor obligations, after tax Earnings per share, Diluted, non-operating gain from sales, write-ups and impairments of investments, and related to sales of businesses, including loss on guarantor obligations Earnings Per Share, Diluted, Non-operating Gain From Sales, Write-ups And Impairments Of Investments, And Related To Sales Of Businesses, Including Loss On Guarantor Obligations Earnings per share, Diluted, non-operating gain from sales, write-ups and impairments of investments, and related to sales of businesses, including loss on guarantor obligations Gain (Loss) on Disposition of Business, Net of Tax Gain (Loss) on Disposition of Business, Net of Tax Amount of gain (loss) from sale of disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant. Earnings Per Share, Diluted, Gain (Loss) on Disposition of Business Earnings Per Share, Diluted, Gain (Loss) on Disposition of Business Earnings per share, diluted, gain from Kaplan University transaction Discrete Deferred Tax Benefit Discrete Deferred Tax Benefit A nonrecurring deferred tax benefit related to valuation allowances Earnings per share, Diluted, nonrecurring discrete deferred state tax benefit related to the release of valuation allowances Earnings Per Share, Diluted, Nonrecurring Discrete Deferred State Tax Benefit Related To The Release Of Valuation Allowances Earnings per share, Diluted, nonrecurring discrete deferred state tax benefit related to the release of valuation allowances Operating lease payments due in 2020 Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months Operating lease payments due in 2021 Lessee, Operating Lease, Liability, Payments, Due Year Two Operating lease payments due in 2022 Lessee, Operating Lease, Liability, Payments, Due Year Three Operating lease payments due in 2023 Lessee, Operating Lease, Liability, Payments, Due Year Four Operating lease payments due in 2024 Lessee, Operating Lease, Liability, Payments, Due Year Five Operating lease payments due thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Leases, operating lease, liability, payments, due, total Lessee, Operating Lease, Liability, Payments, Due Less: Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Total operating lease liability Other Income and Expenses (Narrative) [Abstract] Other Income and Expenses (Narrative) [Abstract] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income [Line Items] Schedule of Non-Operating Income (Expense) [Line Items] [Line Items] for Schedule of Non-Operating Income (Expense) [Table] Loss on Guarantor Lease Obligations Changes in Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Other Intangible Assets Schedule of Finite and Indefinite Lived Intangible Assets [Table Text Block] Schedule of Finite and Indefinite Lived Intangible Assets [Table Text Block] Schedule of assets acquired and liabilities assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Acquisition Pro Forma Financial Information Business Acquisition, Pro Forma Information [Table Text Block] Information related to a Disposal Group Schedule Of Disposal Groups Excluding Discontinued Operations Income Statement Balance Sheet And Additional Disclosures [Table Text Block] Tabular disclosure of information related to a disposal group. Excludes a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.