Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization 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. Investments in Equity Securities Investment, Policy [Policy Text Block] Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Schedule of Estimated Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Pensions and Other Postretirement Benefits Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Award Timing Predetermined Award Timing Predetermined [Flag] Settlement Gains Included In Net Income [Member] Accumulated Defined Benefit Plans Adjustment Settlement Gains Included In Net Income [Member] Accumulated other comprehensive (income) loss related to the settlement gains included in net income component of defined benefit plans attributable to the parent. Indefinite-lived Intangible Assets [Axis] Indefinite-Lived Intangible Assets [Axis] Entity File Number Entity File Number Capital in Excess of Par Value [Member] Additional Paid-in Capital [Member] Advance related to Kaplan University transaction Advance Related To Kaplan University Transaction Advance related to Kaplan University Transaction. Tabular List, Table Tabular List [Table Text Block] Defined benefit plan, target allocation percentage of assets Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Income tax (expense) benefit related to items of other comprehensive income (loss) Other Comprehensive Income (Loss), Income Tax Other Comprehensive Income (Loss), Tax Vesting Condition [Domain] Vesting Condition [Domain] Vesting Condition [Domain] Recently Adopted and Issued Accounting Pronouncemets New Accounting Pronouncements, Policy [Policy Text Block] Mandatory redemption settlement amount Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount Reportable Segment, Aggregation before Other Operating Segment [Member] Reportable Segment, Aggregation before Other Operating Segment [Member] Secured Overnight Financing Rate (SOFR) [Member] Secured Overnight Financing Rate (SOFR) [Member] Investment Manager 2 [Member] Investment Manager 2 [Member] Investment Manager 2 [Member] Share-based Payment Arrangement [Member] Share-Based Payment Arrangement [Member] Goodwill [Line Items] Goodwill [Line Items] Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] 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. Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] 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. Realized gain from termination of interest rate swap Realized gain from termination of interest rate swap Amount of realized gain from the termination of interest rate swap with realized gain recorded as a credit to interest expense. Through 2030 [Member] Loss Carryforwards Expirations Range One [Member] -- None. No documentation exists for this element. -- Schedule of Indefinite-Lived Intangible Assets [Table] Intangible Asset, Indefinite-Lived [Table] Total income tax, Current Current Income Tax Expense (Benefit) Numerator: Numerator [Abstract] Numerator Adjustment to Compensation, Amount Adjustment to Compensation Amount Minimum percentage of plan assets considered as significant concentrations in pension plans Concentration Risk, Percentage 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. Pension Plans [Member] Pension Plan [Member] Pension Plan [Member] Pension credit per employee Pension Credit Retention Program, Credit Per Employee, Amount The amount of pension credit per employee in the pension credit retention program. Contract costs capitalized during the period Contract Costs Capitalized During the Period Capitalized contract costs associated with new contracts entered into during the period. Stock-based compensation expense, net of forfeitures Share-Based Payment Arrangement, Noncash Expense Share awards outstanding, restriction will lapse in 2029 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Four Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Year Four U.S. Federal, Total Federal Income Tax Expense (Benefit), Continuing Operations Share-based Payment Arrangement, Option [Member] Stock Option Plan [Member] Share-Based Payment Arrangement, Option [Member] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Grantee Status [Domain] Grantee Status [Domain] Finance lease, liability, noncurrent Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Effective Income Tax Rate Reconciliation, Percent [Abstract] Effective Income Tax Rate Reconciliation, Percent [Abstract] Ultimate health care cost trend rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Antidilutive Securities [Axis] Antidilutive Securities [Axis] Senior Manager [Member] Senior Manager [Member] Senior Manager Add: Dividends paid–common stock outstanding Dividends, Common Stock, Cash Total Common Stockholders’ Equity Equity, Attributable to Parent Impairment of goodwill and other long-lived assets Impairment of goodwill and other long-lived assets Asset Impairment Charges Measurement Frequency [Axis] Measurement Frequency [Axis] Insider Trading Policies and Procedures [Line Items] Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Common Stock, Shares Authorized Common Stock, Shares Authorized Honda auto dealership [Member] Honda auto dealership [Member] Honda auto dealership World Of Good Brands [Member] WorldOfGoodBrands [Member] World Of Good Brands Member Fair Value, Recurring [Member] Fair Value, Recurring [Member] 5.75% Unsecured Notes maturing in 2026 [Member] Five Point Seven Five Percent Unsecured Notes maturing in 2026 [Member] Five Point Seven Five Percent Unsecured Notes maturing in 2026 [Member] 2028 [Member] Loss Carry Forwards Expirations Year Three [Member] Loss Carry Forwards Expirations Year Three Member Kaplan Stock Option and Restricted Stock [Member] Kaplan Stock Option and Restricted Stock [Member] Kaplan Stock Option and Restricted Stock [Member] Concentration of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Liabilities and Equity Liabilities and Equity [Abstract] State [Member] State and Local Jurisdiction [Member] Cover [Abstract] Cover [Abstract] Maximum [Member] Maximum [Member] 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 Amortized intangible assets useful life (in years) Useful Life (in years) Finite-Lived Intangible Asset, Useful Life Realized and Unrealized Gain (Loss) on Equity Method Investments and Equity Securities Without Readily Determinable Fair Value Realized and Unrealized Gain (Loss) on Equity Method Investments and Equity Securities Without Readily Determinable Fair Value Amount of realized and unrealized gain (loss) on sale or write-downs of equity method investments or investment in equity security without readily determinable fair value. Net Income Attributable to Noncontrolling Interests Net Income (Loss) Attributable to Noncontrolling Interest Rate of compensation increase (percent) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Authorized shares remaining for repurchase Share Repurchase Program, Remaining Authorized, Number of Shares Interest accrued related to unrecognized tax benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Amortized Intangible Assets, Net Net Carrying Amount Finite-Lived Intangible Assets, Net Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets Amount of other assets acquired at the acquisition date. Restricted Stock [Member] Restricted Stock [Member] Deferred Revenue, Period Increase Percentage Deferred Revenue, Period Increase (Decrease) Percentage Deferred Revenue, Period Increase (Decrease) Percentage 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. Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Proceeds from Collection of Advance to Affiliate Proceeds from Collection of Advance to Affiliate Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Kaplan, Graham Media Group, WGB, Saatchi Art, Society6, Code3 and Decile Kaplan, Graham Media Group, WGB, Saatchi Art, Society6, Code3 and Decile [Member] Kaplan, Graham Media Group, WGB, Saatchi Art, Society6, Code3 and Decile Activity Related to Stock Awards Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] Group Dekko [Member] Group Dekko [Member] Group Dekko [Member] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Higher Education [Member] Higher Education [Member] Higher Education [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Total Debt Debt, Long-Term and Short-Term, Combined Amount Stock Options and Contingently Issuable Shares [Member] Stock Options and Contingently Issuable Shares [Member] Stock Options and Contingently Issuable Shares Total lease assets Lease Right-of-Use Asset Amount of right-of-use lease asset Deferred Income Tax Liabilities [Table] Deferred Income Tax Liabilities [Table] Deferred Income Tax Liabilities [Table] Other Indebtedness [Member] Other Indebtedness [Member] Other Indebtedness [Member] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income Before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Issuance of borrowings Proceeds from Issuance of Debt Clyde's Restaurant Group [Member] Clyde's Restaurant Group [Member] Clyde's Restaurant Group Self-Insurance Self Insurance Reserve [Policy Text Block] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments [Member] Operating Segments [Member] Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Medicare Advantage [Member] Medicare Advantage [Member] Medicare Advantage [Member] Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Unrecognized prior service credit Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Pricing Methodology [Domain] Pricing Methodology [Domain] Pricing Methodology [Domain] U.S. Income (Loss) from Continuing Operations before Income Taxes, Domestic Other receivables Other Receivables Current portion of lease liabilities Operating lease, liability, current Operating Lease, Liability, Current Interest on finance lease liabilities Finance Lease, Interest Expense Leases Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Deferred Rent Cumulative realized net gains on sales of marketable securities Marketable Security, Realized Gain (Loss) Document Fiscal Period Focus Document Fiscal Period Focus Rate of compensation increase (percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] Award Timing Method Award Timing Method [Text Block] Award Type [Axis] Award Type [Axis] Foreign Currency Translation Adjustment [Member] Foreign Currency Translation Adjustments [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Number of education business categories Number Of Education Business Categories Number of categories that comprise Kaplan's businesses Acquisition Pro Forma Financial Information Business Combination, Pro Forma Information [Table Text Block] 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. Investment, Name [Domain] Investment, Name [Domain] Equity-Based Compensation Share-Based Payment Arrangement [Policy Text Block] Trading Symbol Trading Symbol Operating lease payments due in 2029 Lessee, Operating Lease, Liability, to be Paid, Year Four Early Retirement Program Expense [Domain] Early Retirement Program Expense [Domain] -- None. No documentation exists for this element. -- Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Entity Address, City or Town Entity Address, City or Town Finance lease, weighted average discount rate, percent Finance Lease, Weighted Average Discount Rate, Percent Cash paid during the year for: Cash Paid During The Year For: [Abstract] -- None. No documentation exists for this element. -- Number of investment companies actively managing plan assets Number Of Investment Companies Managing Plan Assets The number of investment companies actively managing plan assets. Effect of Currency Exchange Rate Change Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Deferred tax assets, net Deferred Tax Assets, Net of Valuation Allowance Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Percent allocated to common stockholders Percentage Of Undistributed Earnings Allocated To Common Stockholders Represents the percentage allocation of undistributed earnings to common stockholders. Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Acquisition purchase price Business Combination, Consideration Transferred Decreases related to settlement with tax authorities Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Impairment on equity method investment Equity Method Investment, Other-than-Temporary Impairment Entity Emerging Growth Company Entity Emerging Growth Company Gross amount Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Pinna [Member] Pinna [Member] Pinna Finance lease, weighted average remaining lease term Finance Lease, Weighted Average Remaining Lease Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Stock options outstanding Beginning, Number of Shares End, Number of Shares Options Outstanding, Shares Outstanding Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Unamortized debt issuance costs Debt Issuance Costs, Net Mary Free Bed at Home [Member] Mary Free Bed at Home [Member] Residential and a Michigan hospital joint venture [Member] 2026 Defined Benefit Plan, Expected Future Benefit Payment, Year One Promissory Note for CSI Minority Shares due 2027 [Member] Promissory Note for CSI Minority Shares due 2027 [Member] Promissory Note for CSI Minority Shares due 2027 Acquisition of business Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Indefinite-Lived Intangible Assets Net Carrying Amount Indefinite-Lived Intangible Assets (Excluding Goodwill) Less: Imputed interest Finance Lease, Liability, Undiscounted Excess Amount Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Share-based Payment Arrangement, Option, Exercise Price Range [Table] Share-Based Payment Arrangement, Option, Exercise Price Range [Table] Carryforwards Period [Axis] Operating Loss Carryforwards [Axis] CarryforwardsPeriod [Axis] -- None. No documentation exists for this element. -- Credit loss expense Accounts Receivable, Credit Loss Expense (Reversal) Estimated Credit Losses [Member] SEC Schedule, 12-09, Allowance, Credit Loss [Member] Investments in marketable equity securities Marketable Securities [Table Text Block] Pension and other postretirement plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Pension Credit Retention Program [Member] Pension Credit Retention Program [Member] Pension credit retention program Prepaid Pension Cost Noncurrent asset Assets for Plan Benefits, Defined Benefit Plan Income taxes payable Accrued Income Taxes, Current Total lease liabilities Lease Liability Present value of lessee's discounted obligation for lease payments from leases Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Provision for Income Taxes Total provision for income tax Income Tax Expense (Benefit) Applicable interest rate margin Debt Instrument, Basis Spread on Variable Rate Class B Common Stock [Member] Common Class B [Member] Audit Information [Abstract] Audit Information [Abstract] Unsecured notes Unsecured Debt Preferred Stock, Shares Issued Preferred Stock, Shares Issued 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. Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Subsegments [Axis] Subsegments [Axis] Capital Stock, Stock Awards, and Stock Options [Abstract] Capital Stock, Stock Awards, and Stock Options [Abstract] -- None. No documentation exists for this element. -- Accounts Receivable Accounts Payable And Accrued Liabilities [Abstract] Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities [Abstract] -- None. No documentation exists for this element. -- Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Capitalized Contract Cost Capitalized Contract Cost [Table Text Block] Property, plant and equipment, gross Property, Plant and Equipment, Gross Organization and Nature of Operations [Line Items] Organization and Nature of Operations [Line Items] Organization and Nature of Operations Exercise Price $846 [Member] Exercise Price $846 [Member] Exercise Price $846 2029 [Member] Loss Carry Forwards Expirations Year Four [Member] Loss Carry Forwards Expirations Year Four Member Vehicle Floor Plan Facility - New Vehicles [Member] Vehicle Floor Plan Facility - New Vehicles [Member] Vehicle Floor Plan Facility - New Vehicles Amortization of lease right-of-use asset Operating Lease, Right-of-Use Asset, Periodic Reduction Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Acquisitions Goodwill, Acquired During Period SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Income taxes receivable/payable Increase (Decrease) in Income Taxes Networking and Programming Expenses Networking and Programming Expenses Expenses related to network fees paid to affiliates and programming expenses through syndicated TV shows Proceeds from Stock Options Exercised Proceeds from Stock Options Exercised Schedule of Error Corrections and Prior Period Adjustments Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] Percentage of Distributions Available to Common Unit Holders Percentage of Distributions Available to Common Unit Holders Percentage of distributions available to common unit holders Acquisitions and Dispositions of Businesses Mergers, Acquisitions and Dispositions Disclosures [Text Block] Investments in certain businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Income taxes paid, net of refunds, U.S. Federal Income Tax Paid, Federal, after Refund Received All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Occupancy Expense Occupancy Expense Amount of net occupancy expense that may include items, such as lease expenses, property taxes and property and casualty insurance expense. Deferred tax assets with respect to U.S. Federal income tax loss carryforwards U.S. Federal income tax loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Domestic Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount 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. Shares subject to award outstanding Beginning of year, unvested, 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, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Realm [Member] Realm [Member] Investment in Realm Number of Automotive Dealerships Owned Number of Automotive Dealerships Owned Number of Automotive Dealerships Owned Deferred tax assets with respect to non U.S. income tax loss carryforwards Non-U.S. income tax loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Foreign 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 Net Cash Provided by Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Options unvested, shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested, Number of Shares Franchise Rights [Member] Franchise Rights [Member] Allegheny Health Network Healthcare at Home [Member] Allegheny Health Network Healthcare at Home [Member] A joint venture formed between Celtic Healthcare and Allegheny Health Network Property, plant and equipment useful life (in years) Property, Plant and Equipment, Useful Life Preferred Stock, Par or Stated Value Per Share Preferred Stock, Par or Stated Value Per Share Subsequent Event [Member] Subsequent Event [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Settlement included in net income Settlement Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax Depreciation of property, plant and equipment Depreciation Expense Depreciation Framebridge [Member] Framebridge [Member] Framebridge [Member] Finance lease payments due in 2029 Finance Lease, Liability, to be Paid, Year Four Loans payable to bank Loans Payable to Bank Investments in equity affiliates and cost method 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. Distribution to noncontrolling interests Temporary Equity, Distribution to noncontrolling interests Decrease in redeemable noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders. Equity Components [Axis] Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Sublease income Sublease Income Change in redemption value of redeemable noncontrolling interests Noncontrolling Interest, Change in Redemption Value GBP revolving credit facility borrowings [Member] GBP revolving credit facility borrowings [Member] GBP revolving credit facility borrowings Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Carryforward Period [Domain] Operating Loss Carryforward Period [Domain] Carryforward Period [Domain] Carryforward Period Domain Operating Costs and Expenses Operating Costs and Expenses [Abstract] Goods [Member] Product [Member] Number of reportable segments Number of Reportable Segments KIHL [Member] KIHL [Member] KIHL [Member] Dividends paid Payments of Ordinary Dividends Summary of Significant Accounting Policies [Line Items] Summary of Significant Accounting Policies [Line Items] -- None. No documentation exists for this element. -- Entity Address, State or Province Entity Address, State or Province Financing cash flows from finance leases (payments) Finance Lease, Principal Payments Operating lease impairment Operating Lease, Impairment Loss Delayed Draw Term Loan [Member] Delayed Draw Term Loan (DDTL) [Member] Dividends paid on common stock Dividends, Common Stock Income from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets Operating Income before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. Operating Income before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. 2029 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Supplier Finance Program [Line Items] Supplier Finance Program [Line Items] 2027 [Member] Loss Carry Forwards Expirations Year Two [Member] Loss Carry Forwards Expirations Year Two [Member] Total Current Liabilities Liabilities, Current Individual: Individual [Axis] Expense associated with the retirement benefits provided under incentive savings plans Defined Contribution Plan, Cost Income Tax Authority [Domain] Income Tax Jurisdiction [Domain] Acquisitions And Dispositions [Abstract] Acquisitions And Dispositions [Abstract] Acquisitions and Dispositions Right-of-use assets obtained in exchange for new finance lease liabilities (noncash) Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Document Annual Report Document Annual Report Settlement of obligation Settlement Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement Cash Equivalents [Member] Defined Benefit Plan, Cash and Cash Equivalents [Member] Proceeds from sale of noncontrolling interest Proceeds from Noncontrolling Interests Periodic Cost [Member] Periodic Cost [Member] Periodic cost assumptions. Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Ownership percentage by non-parent Subsidiary, Ownership Percentage, Noncontrolling Owner Repayments of borrowings Repayments of Long-Term Debt Entity Interactive Data Current Entity Interactive Data Current Transaction Type [Domain] Transaction Type [Domain] Transaction Type [Domain] Toyota auto dealership [Member] Toyota auto dealership [Member] Toyota auto dealership Cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate Funded status Defined Benefit Plan, Funded (Unfunded) Status of Plan Translation adjustments arising during the year Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Home Health Revenue [Member] Home Health Revenue [Member] Home Health Revenue [Member] Intrinsic value of options exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value Periodic payments of principal Debt Instrument, Periodic Payment, Principal Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] 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 Ownership [Domain] Ownership [Domain] Net income attributable to nonredeemable noncontrolling interests Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest Finance lease payments due in 2027 Finance Lease, Liability, to be Paid, Year Two Floor plan assistance Vehicle Floor Plan Facility Assistance The amount of assistance received from the manufacturers recognized as a reduction of operating expenses. Balance at Beginning of Period Balance at End of Period SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount 2027 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Deferred Charges and Other Assets Other Assets, Noncurrent Entity Central Index Key Entity Central Index Key PEO Name PEO Name EBIDTAP EBIDTAP Earnings before interest, income taxes, depreciation, amortization and pension service cost Purdue University Global [Member] Purdue University Global [Member] Purdue University Global Operating Revenues Revenues Cumulative foreign currency translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Curtailment Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Minimum percentage of total assets considered as significant concentrations Concentration Risk, Threshold Percentage For an entity that discloses a concentration risk threshold in relation to a quantitative amount, which serves as the "benchmark", this concept represents the concentration risk threshold percentage related to the "benchmark". GHC Class B Common Stock issued [Member] GHC Class B Common Stock issued [Member] GHC Class B Common Stock issued Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Hospice Revenue [Member] Hospice Revenue [Member] Hospice Revenue [Member] Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Ending Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value State and Local, Total State and Local Income Tax Expense (Benefit), Continuing Operations Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Number of investments in affiliates impaired Number of Equity Method Investments Impaired The number of equity method investments impaired during the period. Additions Supplier Finance Program, Obligation, Addition Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Share-Based Payment Arrangement, First Tranche [Member] Share-Based Payment Arrangement, Tranche One [Member] Deferred revenue recognized in period related to prior year's ending balance Deferred Revenue, Revenue Recognized Work-in-process Inventory, Work in Process, Net of Reserves 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). Advances to Affiliate Advances to Affiliate Contracts in progress Inventory for Long-Term Contracts or Programs, Gross Exercise Price Award Exercise Price Business Combination, Series of Individually Immaterial Business Combinations [Member] Business Combination, Series of Individually Immaterial Business Combinations [Member] Entity Filer Category Entity Filer Category Class of Stock [Domain] Class of Stock [Domain] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid U.S. Federal taxes at statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Subsequent Event Type [Axis] Subsequent Event Type [Axis] Non-U.S., Total Foreign Income Tax Expense (Benefit), Continuing Operations Long-Term Debt Total Long-Term Debt Long-Term Debt, Excluding Current Maturities Pricing Methodology [Axis] Pricing Methodology [Axis] Pricing Methodology Estimated amortization of intangible assets, 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Three Vesting [Domain] Vesting [Domain] Retirement Benefits, Description [Abstract] Retirement Benefits, Description [Abstract] Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassifications, before tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Gross Carrying Amount Finite-Lived Intangible Assets, Gross Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One AOCI Attributable to Parent [Member] AOCI Attributable to Parent [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. Redeemable Noncontrolling Interests As of As of Redeemable Noncontrolling Interest, Equity, Carrying Amount Special termination benefits Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits Ownership [Axis] Ownership [Axis] Amortization of prior service (credit) cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit Low Exercise Price Range Share-Based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit Foreign currency translation adjustments: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent [Abstract] Fair Value as of Grant Date Award Grant Date Fair Value Total cost Equity Securities, FV-NI, Cost Payroll and Fringe Benefits Expense Compensation Expense, Excluding Cost of Good and Service Sold Undistributed earnings Undistributed Earnings, Basic U.S. equities [Member] Defined Benefit Plan, Equity Securities, US [Member] Summary of Other Non-Operating (Expense) Income Schedule of Other Nonoperating Income (Expense) [Table Text Block] Components of Debt Schedule of Long-Term Debt Instruments [Table Text Block] Add: Effect of dilutive stock options (shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Number of shares awarded Awarded, Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Title of Individual with Relationship to Entity [Domain] Title and Position [Domain] Total Operating Costs and Expenses Costs and Expenses Forfeited, Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Total unrecognized compensation expense Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Foreign exchange swap Foreign Currency Contract, Asset, Fair Value Disclosure Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Counterparty Name [Domain] Counterparty Name [Domain] Operating lease payments due in 2027 Lessee, Operating Lease, Liability, to be Paid, Year Two Revenue Source [Axis] Revenue Source [Axis] Revenue Source [Axis} Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Receivables/(payables), net [Member] Receivables (Payables) [Member] -- None. No documentation exists for this element. -- 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 Fair Value, Investments, Entities that Calculate Net Asset Value Per Share Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block] Schedule of Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] Value of investments Investments Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount 2028 Defined Benefit Plan, Expected Future Benefit Payment, Year Three Number of dealerships Number of Stores Amortization of net actuarial gain included in net income Recognized net actuarial gain Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] (Repayments of) proceeds from bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Non-PEO NEO Non-PEO NEO [Member] Intrinsic value of options outstanding Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Leases Deferred Tax Liabilities, Leasing Arrangements Goodwill Impairment Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Goodwill Impairment Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Goodwill Impairment Loss Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Lessee, operating lease, lease not yet commenced, term of contract Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Other [Member] Other Intangible Assets [Member] Land [Member] Land [Member] Net Prior Service Cost [Member] Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Award Type [Domain] Award Type [Domain] Operating lease payments due in 2026 Lessee, Operating Lease, Liability, to be Paid, Year One Noncontrolling Interests Equity, Attributable to Noncontrolling Interest Equity Awards Adjustments Equity Awards Adjustments [Member] Leasehold Improvements [Member] Leasehold Improvements [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Minimum Term of Contract Minimum Term of Contract Minimum Term of Contract Total Payments due for Redemption of Noncontrolling Interest Total Payments due for Redemption of Noncontrolling Interest Total Payments due for Redemption of Noncontrolling Interest Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Pre-Age 65 [Member] Pre-Age 65 [Member] Pre-Age 65 [Member] Subsegments [Domain] Subsegments [Domain] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Cumulative realized gain on marketable securities donated Cumulative realized gain (loss) on marketable securities donated Cumulative realized gain (loss) on marketable securities donated Retirement Plan Type [Domain] Retirement Plan Type [Domain] Additions - Charged to Costs and Expenses SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense Schedule of Investments [Line Items] Schedule of Investments [Line Items] Schedule of Changes in Estimated Credit Losses Accounts Receivable, Allowance for Credit Loss [Table Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Foreign income tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent AUSTRALIA AUSTRALIA Deferred income taxes Business Combination, Recognized Asset Acquired, Deferred Tax Asset Recipient of Consideration [Axis] Recipient of Consideration [Axis] Recipient of Consideration Kaplan Corporate and Other [Member] Kaplan Corporate and Other [Member] Kaplan Corporate And Other [Member] Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Loss) Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Documents Incorporated by Reference [Text Block] Documents Incorporated by Reference [Text Block] Finance lease assets Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Long-term Contract with Customer [Member] Long-Term Contract with Customer [Member] Goodwill, beginning balance Goodwill, ending balance Goodwill, Gross Contingent consideration liabilities [Member] Contingent consideration liabilities [Member] Contingent consideration liabilities Deferred tax liabilities Deferred Tax Liabilities, Gross USD revolving credit facility borrowings [Member] USD revolving credit facility borrowings [Member] USD revolving credit facility borrowings Impairment Of Intangible Asset Indefinite Lived Excluding Goodwill Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Impairment Of Intangible Asset Indefinite Lived Excluding Goodwill Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Impairment Of Intangible Asset Indefinite Lived Excluding Goodwill Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag Accumulated other comprehensive income, net of taxes Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Other Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Business Combination, Achieved in Stages, Preacquisition and Acquired Equity Interests in Acquiree, Percentage Business Combination, Achieved in Stages, Preacquisition and Acquired Equity Interests in Acquiree, Percentage Payment for settlement Defined Benefit Plan, Benefit Obligation, Payment for Settlement Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Minimum [Member] Minimum [Member] Year that rate reaches ultimate trend rate Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate Measurement period adjustment Goodwill, Measurement Period Adjustment Company Selected Measure Name Company Selected Measure Name Education [Member] Education [Member] Education [Member] Early Retirment Program Expense [Domain] Early Retirment Program Expense [Domain] Early Retirment Program Expense [Domain] Net income Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax Debt Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts Payable, Current Operating cash flows from operating leases (payments) Operating Lease, Payments Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Graham Holdings Company Common Stockholders: Income Per Share From Continuing Operations To Common Stockholders [Abstract] Income Per Share From Continuing Operations To Common Shareholders. Other Comprehensive Income (Loss), Before Tax Other Comprehensive Income (Loss), Before Tax Other Comprehensive Income (Loss), before Tax 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. Investment Manager 1 [Member] Investment Manager 1 [Member] Investment Manager 1 [Member] Numerator for diluted earnings per share Net Income (Loss) Available to Common Stockholders, Diluted Television Broadcasting [Member] Television Broadcasting [Member] Television Broadcasting [Member] Non-U.S., Current Current Foreign Tax Expense (Benefit) Claims discharge loan amount Loss Contingency Borrower Defense Claims Discharge Loan Amount The amount of money applications seek to discharge of loans. Goodwill [Roll Forward] Goodwill [Roll Forward] Other Healthcare Services [Member] Other Healthcare Services [Member] Other Healthcare Services [Member] Contingencies and Other Commitments Commitments and Contingencies Disclosure [Text Block] Share-Based Payment Arrangement, Second Tranche [Member] Share-Based Payment Arrangement, Tranche Two [Member] Diluted average number of common shares outstanding (in shares) Denominator for diluted earnings per share (shares) Weighted Average Number of Shares Outstanding, Diluted 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. Cash paid to settle a significant portion of the mandatorily redeemable noncontrolling interest [Member] Cash paid to settle a significant portion of the mandatorily redeemable noncontrolling interest [Member] Cash paid to settle a significant portion of the mandatorily redeemable noncontrolling interest Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities [Line Items] Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities [Line Items] Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Entity Small Business Entity Small Business Percentage of interest acquired Business Combination, Voting Equity Interest Acquired, Percentage Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Deferred income tax liabilities related to undistributed earnings of investments in non-U.S. subsidiaries Non-U.S. withholding tax Deferred Tax Liabilities, Undistributed Foreign Earnings Databases and Technology [Member] Database Rights [Member] CSI Pharmarcy [Member] CSI [Member] CSI Pharmacy [Member] CSI Pharmacy [Member] State and Local, Current Current State and Local Tax Expense (Benefit) Document Transition Report Document Transition Report Supplier Finance Program, Obligation [Roll Forward] Supplier Finance Program, Obligation [Roll Forward] Finance lease liabilities, total payments due Finance Lease, Liability, to be Paid Underlying Securities Award Underlying Securities Amount Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Income Taxes Income Tax Disclosure [Text Block] Depreciation, amortization and goodwill and other long-lived asset impairments 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. Estimated credit losses Accounts Receivable, Allowance for Credit Loss Class A Common Stock [Member] Common Class A [Member] UNITED KINGDOM UNITED KINGDOM Deferred payments of acquisitions Payment for Contingent Consideration Liability, Financing Activities Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Schedule of Investments [Table] Schedule of Investments [Table] Accretion of value included in net income Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Gain (Loss), Accretion Included in Earnings Amount of gain (loss) recognized in income from accretion from liability measured at fair value on recurring basis using unobservable input (level 3). 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 Lease liabilities Increase (Decrease) in Operating Lease Liability Total Equity As of As of Equity, Including Portion Attributable to Noncontrolling Interest Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] Share-Based Payment Arrangement, Option, Exercise Price Range [Line Items] Foreign currency exchange rate changes Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Foreign Currency Translation Gain (Loss), Amount of foreign currency translation of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. Document Type Document Type Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Name Outstanding Recovery, Individual Name Advertising and Marketing Expense Marketing and Advertising Expense Loss Contingencies [Table] Loss Contingencies [Table] Capital in excess of par value Additional Paid in Capital Accounts receivable, net Accounts receivable, net Accounts receivable, current Accounts and Other Receivables, Net, Current Product and Service [Axis] Product and Service [Axis] Income tax loss carryforwards obtained as a result of prior stock acqusitions Income tax loss carryforwards to be fully utilized Tax Loss Carryforward Prior Stock Acquisition Utilized Income tax loss carryforwards obtained as a result of prior stock acqusitions to be fully utilized. Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities Accounts Receivable Accounts Payable And Accrued Liabilities [Text Block] The entire disclosure of Accounts Receivable Accounts Payable And Accrued Liabilities Variable lease cost Variable Lease, Cost Operating Revenues Revenue from Contract with Customer, Excluding Assessed Tax GHC One [Member] GHC One and GHC Two [Member] GHC One [Member] Leaf Group and Code3 [Member] Leaf Group and Code3 [Member] Leaf Group and Code3 Gain related to contingent consideration Gain Related to Contingent Consideration Contingent consideration gain related to the sale of a business. Total Current Assets Assets, Current Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain] Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain] Statistical Measurement [Axis] Statistical Measurement [Axis] Gain on sale of investment in affiliates Equity Method Investment, Realized Gain (Loss) on Disposal 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 5.625% Unsecured Notes maturing in 2033 [Member] Five Point Six Two Five Percent Unsecured Notes maturing in 2033 [Member] Five Point Six Two Five Percent Unsecured Notes maturing in 2033 [Member] Healthcare [Member] Healthcare Divison [Member] Healthcare Divison Maximum Term of Contract Maximum Term of Contract Maximum Term of Contract Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Intrinsic value of options exercised Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Numerator for basic earnings per share Net Income (Loss) Available to Common Stockholders, Basic Kaplan, Dekko, WGB, Decile and Foreign Policy [Member] Kaplan, Dekko, WGB and Decile [Member] Kaplan, Dekko, WGB and Decile Graham Media Group and Corporate [Member] Graham Media Group and Corporate [Member] Graham Media Group and Corporate Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] Current Liabilities Liabilities, Current [Abstract] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Line of credit facility outstanding Credit Facility Long-Term Line of Credit CSI Pharmacy Holding Company, LLC [Member] CSI Pharmacy Holding Company, LLC [Member] CSI Pharmacy Holding Company, LLC [Member] Gain on disposition of businesses, property, plant and equipment, investments and other assets, net Gain (Loss) on Disposition of Assets Purchase of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Diluted net income per common share (in USD per share) Diluted earnings per common share (in USD per share) Earnings Per Share, Diluted Receivables from contracts with customers, less estimated credit losses Accounts Receivable, after Allowance for Credit Loss, Current Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] 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] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Schedule of Assumptions Used Defined Benefit Plan, Assumptions [Table Text Block] Mandatorily Redeemable Noncontrolling Interest Effective Income Tax Rate Reconciliation, Mandatorily Redeemable Noncontrolling Interest Change in Fair Value, Percent Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to the change in fair value of mandatorily redeemable noncontrolling interest. Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities [Table] Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities [Table] Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities Treasury Stock, Common, Shares Treasury Stock, Common, Shares Income taxes paid, net of refunds, State Income Tax Paid, State and Local, after Refund Received Consolidation Items [Domain] Consolidation Items [Domain] 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 Pension liabilities Business Combination, Recognized Liability Assumed, Pension Liabilities Amount of pension liabilities assumed in business combination and recognized at acquisition date. Auditor Location Auditor Location Deferred Revenue Recognized of Refundable Prepaid Amounts DeferredRevenueRecognizedofRefundablePrepaidAmounts Amount of revenue recognized that was previously reported as deferred or unearned revenue that relates to prepaid amounts that were refundable. Goodwill impairments Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount 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. Actuarial loss (gain) Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Comprehensive Income Comprehensive Income, Policy [Policy Text Block] U.S. Federal [Member] Domestic Tax Jurisdiction [Member] Amendments Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Less: Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount 2030 [Member] Loss Carry Forwards Expirations Year Five [Member] Loss Carry Forwards Expirations Year Five Member Money market investments Money Market Funds, at Carrying Value Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Other Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent Income taxes Income taxes paid Income Taxes Paid, Net Estimated amortization of intangible assets, 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Two 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 Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Accrued compensation and related benefits Employee-related Liabilities, Current Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Operating lease liabilities, total payments due Lessee, Operating Lease, Liability, to be Paid Arconic Architectural Products, LLC [Member] Arconic Architectural Products, LLC [Member] Arconic Architectural Products, LLC Credit facility current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Distribution to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Total investments [Member] Total Investments [Member] -- None. No documentation exists for this element. -- Total pension and other postretirement plans Total Recognized in Other Comprehensive Income (Before Tax Effects) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Number of shares held in investment Investment Owned, Balance, Shares Intersegment Elimination [Member] Intersegment Eliminations [Member] Expiration Date Trading Arrangement Expiration Date Intersubsegment Eliminations [Member] Intersubsegment Eliminations [Member] Estimated amortization of intangible assets, 2030 Finite-Lived Intangible Asset, Expected Amortization, Year Five Term Loan maturing in 2027 [Member] Term Loan maturing in 2027 [Member] Term Loan maturing in 2027 Common Stockholders’ Equity Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Fixed income securities [Member] Fixed Income Securities [Member] Net unrealized gains in earnings from marketable equity securities still held at the end of the year Equity Securities, FV-NI, Unrealized Gain (Loss) GHC One [Member] GHC One [Member] GHC One Property, Plant and Equipment, Net Property, plant and equipment, net Property, Plant and Equipment, Net Geographic Concentration [Member] Geographic Concentration Risk [Member] Cumulative undistributed income in investments in affiliates Retained Earnings, Undistributed Earnings from Equity Method Investees 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. Distributions paid to noncontrolling interests Payments of Capital Distribution Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Accounts receivable Increase (Decrease) in Accounts Receivable Inventories and Contracts in Progress Inventory, Policy [Policy Text Block] Entity Current Reporting Status Entity Current Reporting Status Graham Healthcare Group [Member] Graham Healthcare Group [Member] Graham Healthcare Group [Member] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] 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). U.S. Federal taxes at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Transaction [Domain] Transaction [Domain] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Kaplan, Dekko, WGB, Saatchi Art, Society6, Slate and Decile [Member] Kaplan, Dekko, WGB, Saatchi Art, Society6, Slate and Decile [Member] Kaplan, Dekko, WGB, Saatchi Art, Society6, Slate and Decile State and local taxes, net of U.S. Federal tax Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent 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. Finance lease, liability, current Finance Lease, Liability, Current Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Investment Managers [Axis] Investment Managers [Axis] Investment Managers [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Assumed health care cost trend rate Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year 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. Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Floor plan payables Floor plan payables Vehicle floor plan payable Vehicle Floor Plan Facility Payable The amount borrowed to finance the purchase of specific vehicle inventories. Income before Income Taxes [Abstract] Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest [Abstract] Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] 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] Shares available for future awards Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Reallocation Goodwill, Transfers Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Amortization of net prior service (credit) cost included in net income Amortization of prior service credit (cost) Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Automotive [Member] Automotive [Member] Automotive [Member] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Proceeds from sales of marketable equity securities Proceeds from Sale and Maturity of Marketable Securities Marketable Equity Securities Investments in Marketable Equity Securities Equity Securities, FV-NI, Current Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Beginning unrecognized tax benefits Ending unrecognized tax benefits Unrecognized Tax Benefits Number of Performance Obligations Number of Performance Obligations Number of Performance Obligations in standard contract Impact Medical[Member] Impact Medical [Member] Impact Medical Shares excluded from earnings per share Antidilutive securities, shares Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Accounts payable, vehicle floor plan payable and accrued liabilities Total accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Leases Lessee, Operating Leases [Text Block] Net Cash Used in Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Measure: Measure [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] 2022 Incentive Compensation Plan [Member] 2022 Incentive Compensation Plan [Member] 2022 Incentive Compensation Plan Estimated amortization of intangible assets, after 2030 Finite-Lived Intangible Asset, Expected Amortization, after Year Five Debt [Table] Debt [Table] Schedule of all debt, including both short term and long term. 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 Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Issuance of Class B common stock, net of restricted stock award forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Net Actuarial Loss [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] 2026 [Member] 2026 [Member] 2026 [Member] Cost of services and goods Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization 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. Number of businesses acquired Business Combination, Number of Businesses Acquired Summary of Amounts and Line Items of Reclassifications out of Accumulated Other Comprehensive Income (Loss) Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Skin Clique Skin Clique [Member] Skin Clique Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Obligations outstanding at the beginning of the year Obligations outstanding at the end of the year Supplier Finance Program, Obligation Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Entity Tax Identification Number Entity Tax Identification Number Grantee Status [Axis] Grantee Status [Axis] Share awards outstanding, restriction will lapse in 2027 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 Beginning, Average Option Price (in dollars per share) End, Average Option Price (in dollars per share) Options Outstanding, Weighted Average Exercise Price (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Common Stock, Shares, Issued Common Stock, Shares, Issued Other Healthcare Businesses [Member] Other Healthcare [Member] Other Healthcare [Member] Other Healthcare Businesses Operating lease, weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Clarus [Member] Clarus [Member] Clarus Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Entity Public Float Entity Public Float Settlements Supplier Finance Program, Obligation, Settlement Changes in Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Interest expense Interest expense Interest Expense, Nonoperating Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Unrecognized actuarial gain Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Corporate office [Member] Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Security Exchange Name Security Exchange Name Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible Enumeration] Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible Enumeration] Income taxes paid, net of refund, Non-U.S. Income Tax Paid, Foreign, after Refund Received Goodwill and Intangible Asset Impairment Goodwill and Intangible Asset Impairment Mandatorily redeemable noncontrolling interest Mandatorily redeemable noncontrolling interest, Current Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Current 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] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-Lived Intangible Assets, Major Class Name [Domain] Prepaid expenses Prepaid Expense, Current Discount rate to determine periodic cost Discount rate (percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Noncurrent liability Liability, Defined Benefit Plan, Noncurrent Net Periodic 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. Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Statement [Line Items] Statement [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Debt extinguishment amount Extinguishment of Debt, Amount Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent Common Stock [Member] Common Stock [Member] Vested, Number of Shares Vested, Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Mandatorily Redeemable Noncontrolling Interest Mandatorily Redeemable Noncontrolling Interest [Policy Text Block] Mandatorily Redeemable Noncontrolling Interest [Policy Text Block] Net Increase in Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Advertising Revenue [Member] Advertising Revenue [Member] Advertising Revenue [Member] Gain on marketable equity securities and cost method investments, net Unrealized Gain (Loss) on Investments Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Property, plant and equipment Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment Operating lease payments due thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] 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 Goodwill impairments Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent Goodwill expected to be deductible for income tax purposes Business Combination, Goodwill, Expected Tax Deductible, Amount Interest Rate Swaps maturing in 2031 and 2032 [Member] Interest Rate Swap [Member] Tax Jurisdiction of Domicile [Extensible Enumeration] Tax Jurisdiction of Domicile [Extensible Enumeration] Payments of financing costs Payments of Financing Costs Evaluation of Long-Lived Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Code3 [Member] Code3 [Member] Code3 Other Non-Operating (Expense) Income Other Income and Other Expense Disclosure [Text Block] Equity in earnings (losses) of affiliates, net Gain in equity earnings Income (Loss) from Equity Method Investments Leases [Abstract] Leases [Abstract] Increases related to prior year tax positions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Gain on sale of cost method investments Equity Securities without Readily Determinable Fair Value, FV-NI, Realized Gain (Loss) Amount of realized gain (loss) from sale of investment in equity security without readily determinable fair value with change in fair value recognized in net income (FV-NI). Supplier Finance Program [Axis] Supplier Finance Program [Axis] Contract Asset, Current Contract with Customer, Asset, after Allowance for Credit Loss, Current Interest Expense, Net Interest expense, net Interest Income (Expense), Nonoperating SINGAPORE SINGAPORE Shares withheld related to net share settlement Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Contributions to multiemployer pension plans Multiemployer Plan, Employer Contribution, Cost 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. Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic net income per common share (in USD per share) Basic earnings per common share (in USD per share) Earnings Per Share, Basic Issuance of noncontrolling interest Proceeds from Contributed Capital Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Shares reserved for issuance Common Stock, Capital Shares Reserved for Future Issuance Accretion expense and change in fair value of contingent consideration liabilities AccretionExpenseAndChangeInFairValue Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values. Also includes change in fair value of liability. Mandatorily redeemable noncontrolling interest [Member] Mandatorily redeemable noncontrolling interest [Member] Mandatorily redeemable noncontrolling interest Deferred tax assets Deferred Tax Assets, Gross Discount rate to determine benefit obligation Discount rate (percent) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Tax benefit from stock option exercises Share-Based Payment Arrangement, Exercise of Option, Tax Benefit Other Comprehensive Income (Loss), Net of Tax Other comprehensive income (loss), net of income taxes Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Summary of Segment Reporting Information, by Operating Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] 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. Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Organization and Nature of Operations [Table] Organization and Nature of Operations [Table] Organization and Nature of Operations 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. Finance lease payments due in 2028 Finance Lease, Liability, to be Paid, Year Three Employee benefit obligations Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Indefinite-lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets [Line Items] Foreign tax credit carryforwards Foreign Tax Credit Carryforwards Foreign tax credits available to be credited against future U.S. Federal income tax liabilities. Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Vesting Condition [Axis] Vesting Condition [Axis] Vesting Condition Stock-based compensation expense Share-Based Payment Arrangement, Expense Finance lease, liability, current Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current Assets Assets, Current [Abstract] Total Liabilities and Equity Liabilities and Equity Capital contributions Fair Value, Measurement With Unobservable Inputs Reconciliations, Recurring Basis, Liability, Capital Contributions Fair Value, Measurement With Unobservable Inputs Reconciliations, Recurring Basis, Liability, Capital Contributions Specialty Pharmacy Specialty Pharmacy [Member] Specialty Pharmacy Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Pension and Other Postretirement Plans [Member] Unrealized Gain (Loss) on Pensions and Other Postretirement Plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Guaranteed Return Guaranteed Return Preferred annual return on portfolio investments guaranteed to the Company Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Net income attributable to redeemable noncontrolling interests Temporary Equity, Net Income Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Other Nonoperating Income (Expense) [Abstract] Other Nonoperating Income (Expense) [Abstract] Capital Expenditures Segment, Expenditure, Addition to Long-Lived Assets Accounting Policies [Abstract] Accounting Policies [Abstract] Health Care [Member] Health Care [Member] Average borrowings outstanding Average Outstanding Debt Amount Average borrowings outstanding during the period, both short and long term. Maturities of Lease Liabilities Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Kaplan Restricted Stock [Member] Kaplan Restricted Stock [Member] -- None. No documentation exists for this element. -- Effective Income Tax Rate Reconciliation, State and Local Jurisdiction, Contribution Greater than 50 Percent, Tax Effect [Extensible Enumeration] Effective Income Tax Rate Reconciliation, State and Local Jurisdiction, Contribution Greater than 50 Percent, Tax Effect [Extensible Enumeration] Concentration Risk Type [Domain] Concentration Risk Type [Domain] 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] Non-operating pension and postretirement benefit income, net Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component Treasury Stock, Common Treasury Stock, Common [Member] Pay vs Performance Disclosure [Line Items] Total operating lease liabilities Operating Lease, Liability Loss on cost method investments Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Annual Amount Liabilities Liabilities [Abstract] Separation Incentive Program [Member] Separation Incentive Program [Member] Separation Incentive Program [Member] Schedule of Changes in Deferred Tax Valuation Allowance Summary of Valuation Allowance [Table Text Block] Total Financial Liabilities Financial Liabilities Fair Value Disclosure Number of television broadcast stations owned Number Of Television Broadcast Stations Owned Number of television broadcast stations owned by the Company. Amortization of finance ROU assets Finance Lease, Right-of-Use Asset, Amortization Mandatorily redeemable noncontrolling interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Fair Value of Shares Other Liabilities Other Liabilities, Noncurrent Schedule Of Supplemental Cash Flow Information Related To Leases Schedule Of Supplemental Cash Flow Information Related To Leases [Text Block] Schedule Of Supplemental Cash Flow Information Related To Leases Deferred revenue Increase (Decrease) in Deferred Revenue Additional Amount Payable for CSI Minority Shares [Member] Additional Amount Payable for CSI Minority Shares [Member] Additional Amount Payable for CSI Minority Shares 2026 [Member] Loss Carry Forwards Expirations Year One [Member] Loss Carry Forwards Expirations Year One Member Goodwill, Impairment Loss Impairment Goodwill, Impairment Loss 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. Purchase of noncontrolling interest Payments for Repurchase of Redeemable Noncontrolling Interest Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Current portion of long-term debt Less: current portion of long-term debt Long-Term Debt, Current Maturities Company Selected Measure Amount Company Selected Measure Amount Company contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Operating lease payments due in 2028 Lessee, Operating Lease, Liability, to be Paid, Year Three Total Comprehensive Income Attributable to Graham Holdings Company Comprehensive Income (Loss), Net of Tax, Attributable to Parent York Joint Venture [Member] York Joint Venture [Member] York Joint Venture [Member] Name Measure Name Schedule of Income Before Income Taxes, Domestic and Foreign Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Securities Subject to Mandatory Redemption [Member] Securities Subject to Mandatory Redemption [Member] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Income tax loss carryforwards to expire Income Tax Loss Carryforwards Subject to Expiration Income tax loss carryforwards subject to expiration. Schedule of Non-Operating (Expense) Income [Line Items] Schedule of Non-Operating Income (Expense) [Line Items] [Line Items] for Schedule of Non-Operating Income (Expense) [Table] Deferred Income Taxes Deferred Income Tax Liabilities, Net 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 Sterling Overnight Interbank Average Rate (SONIA) [Member] Sterling Overnight Interbank Average Rate (SONIA) [Member] Average of the interest rates that banks pay to borrow sterling overnight from other financial institutions and other institutional investors. Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] Options outstanding exercisable in 2026 (shares) Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Year Two Options outstanding exercisable in year one. Deferred tax assets with respect to U.S. Federal foreign tax credit carryforwards U.S Federal foreign income tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards, Foreign Summary of Other Comprehensive Income (Loss) Comprehensive Income (Loss) [Table Text Block] Legal Entity [Axis] Legal Entity [Axis] Total Assets Assets Estimated amortization of intangible assets, 2026 Finite-Lived Intangible Asset, Expected Amortization, Year One Options unvested, average exercise price (in dollars per share) 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. Cash Paid for CSI Minority Shares [Member] Cash Paid for CSI Minority Shares [Member] Cash Paid for CSI Minority Shares 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 Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Unrealized gain on pensions and other postretirement plans Net amount Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Geographical [Domain] Geographical [Domain] Income Taxes Income Tax, Policy [Policy Text Block] Cash Flows from Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Other Segment Items Segment Reporting, Other Segment Item, Amount Translation adjustments arising during the year Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Amount borrowed to finance business acquisition Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition Concentration Risk by Type [Axis] Concentration Risk Type [Axis] Inventories and Contracts in Progress Inventory Disclosure [Text Block] 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 Private investment fund [Member] Private Equity Funds [Member] 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. Capital Contributor [Domain] Capital Contributor [Domain] [Domain] for Capital Contributor [Axis] 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] Estimated amortization of intangible assets, 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Four Dividends declared per common share Common Stock, Dividends, Per Share, Declared Finance lease payments due in 2026 Finance Lease, Liability, to be Paid, Year One Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Balance of costs to obtain a contract Capitalized Contract Cost, Net Right-of-use assets obtained in exchange for new operating lease liabilities (noncash) Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] State and local taxes, net of U.S. Federal tax Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Investments in Affiliates Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Combination [Domain] Business Combination [Domain] 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 Related Party [Member] Related Party [Member] Capital Contributor [Axis] Capital Contributor [Axis] Capital Contributor [Axis] Purchase of noncontrolling interest Nonredeemable Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Decrease in nonredeemable noncontrolling interest (for example, but not limited to, redeeming or purchasing the interests of noncontrolling shareholders, issuance of shares (interests) by the non-wholly owned subsidiary to the parent entity for other than cash, and a buyback of shares (interest) by the non-wholly owned subsidiary from the noncontrolling interests). Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Schedule of Provision for Income Taxes on Income Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Accounts receivable Deferred Tax Asset, Tax Deferred Expense, Reserve and Accrual, Accounts Receivable, Allowance for Credit Loss Plan Name [Axis] Plan Name [Axis] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Supplemental Balance Sheet Information Related To Leases Schedule Of Supplemental Balance Sheet Information Related To Leases [Table Text Block] Schedule Of Supplemental Balance Sheet Information Related To Leases PEO PEO [Member] 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 Interest income Investment Income, Interest Income Tax Paid, by Individual Jurisdiction [Line Items] Income Tax Paid, by Individual Jurisdiction [Line Items] Other Businesses and Corporate Office [Member] Corporate Segment and Other Operating Segment [Member] U.S. [Member] UNITED STATES Change in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Property, plant and equipment Deferred Tax Liabilities, Property, Plant and Equipment Retained Earnings [Member] Retained Earnings [Member] Income Tax Authority [Axis] Income Tax Jurisdiction [Axis] Cash and Cash Equivalents and Restricted Cash at Beginning of Year Cash and Cash Equivalents and Restricted Cash at End of Year Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Purchases of marketable equity securities Payments to acquire marketable securities Payments to Acquire Marketable Securities Total Financial Assets Investments, Fair Value Disclosure Fair value of Kaplan common stock (in dollars per share) Fair Value Of Company Common Stock Fair value of company common stock Product and Service [Domain] Product and Service [Domain] Acquisition-related costs Business Combination, Transaction Cost, Excluding Separately Recognized Transaction Net Income Net Income Net income for the year Net of Tax Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Reportable Subsegments [Member] Reportable Subsegments [Member] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Business Combination [Table] Business Combination [Table] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Income Tax Paid, by Individual Jurisdiction [Table] Income Tax Paid, by Individual Jurisdiction [Table] Schedule of assets acquired and liabilities assumed Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] Direction of change for assumed health care cost trend rate Defined Benefit Plan, Assumed Health Care Cost Trend Rate, Description City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Investments Investment [Text Block] Additional Contract Assets [Member] Additional Contract Assets [Member] Additional Contract Assets Kaplan, Graham Media Group, Joyce, Society6, Saatchi Art, Code3 and Corporate Kaplan, Graham Media Group, Joyce, Society6, Saatchi Art, Code3 and Corporate [Member] Kaplan, Graham Media Group, Joyce, Society6, Saatchi Art, Code3 and Corporate Settlements or distributions Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Contract with Customer, Liability Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Deferred Income Tax Liabilities, Net Deferred Tax Liabilities, Net Cash Flows from Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Percentage of Contributed Capital Percentage of Contributed Capital Percentage of Contributed Capital 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. Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Framebridge and Code3 [Member] Framebridge and Code3 [Member] Framebridge and Code3 Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Net pension obligations Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension Liabilities, Net Amount of net pension liabilities assumed at the acquisition date 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 Recognized actuarial gain Defined Benefit Plan, Amortization of Gain (Loss) 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. Cash balance interest crediting rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate Goodwill, Net Goodwill Goodwill, net, beginning balance Goodwill, net, ending balance Goodwill Loss contingency, estimate of possible loss Loss Contingency, Estimate of Possible Loss Components of Expense Lease, Cost [Table Text Block] Property, plant and equipment impairment charges Tangible Asset Impairment Charges Benefit Obligation [Member] Benefit Obligation [Member] Benefit obligation assumptions. U.S. Federal, Deferred Deferred Federal Income Tax Expense (Benefit) Non U.S. [Member] Non-US [Member] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Unrecognized Tax Benefits [Roll Forward] Auditor Name Auditor Name Organization and Nature of Operations Nature of Operations [Text Block] Identifiable Assets Identifiable Assets Identifiable assets by segment are those assets used in the Company's operations in each business segment. Inventory Business Combination, Recognized Asset Acquired, Inventory, Current 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. Capital loss carryforward [Member] Capital Loss Carryforward [Member] Schedule of Income Tax Loss Carryforwards Summary of Operating Loss Carryforwards [Table Text Block] Supplemental Cash Flow Information Supplemental Cash Flow Information [Abstract] Valuation allowance related to operating loss carryforwards Operating Loss Carryforwards, Valuation Allowance Accounts receivable Business Combination, Recognized Asset Acquired, Receivable, Current Accumulated impairment losses, beginning balance Accumulated impairment losses, ending balance Goodwill, Impaired, Accumulated Impairment Loss Other Performance Measure, Amount Other Performance Measure, Amount 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] Price-Based Price-Based [Member] Price-Based Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Gain on marketable equity securities, net Gain on marketable equity securities, net Gain on marketable equity securities, net Equity Securities, FV-NI, Gain (Loss) Stock compensation payouts Deferred Compensation Arrangement with Individual, Distribution Paid Benefits paid Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Vesting [Axis] Vesting [Axis] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Education and Healthcare Divisions [Member] Education and Healthcare Divisions [Member] Education and healthcare divisions Other current assets Other Assets, Current Investments [Abstract] Investments [Abstract] Entity [Domain] Entity [Domain] Settlement Defined Benefit Plan, Plan Assets, Payment for Settlement Net Cash Used in Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis] Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis] Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Gain on sale of businesses Gain (Loss) on Disposition of Business Interest Interest Paid, Excluding Capitalized Interest, Operating Activity Liquidation Period [Domain] Liquidation Period [Domain] [Domain] for Liquidation Period [Axis] Document Fiscal Year Focus Document Fiscal Year Focus Lease Right-of-Use Assets Lease right-of-use assets Operating Lease, Right-of-Use Asset Post-Age 65 [Member] Post Age 65 [Member] Post Age 65 [Member] Provision for Income Taxes Effective Income Tax Rate Reconciliation, Percent Other Businesses [Member] Other Businesses [Member] Other Operating Segment [Member] Decrease related to prior year tax positions Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Operating lease cost Operating Lease, Cost Plan Name [Domain] Plan Name [Domain] Years over which cost expected to be recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Exercised, Number of Shares Exercised, Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Valuation allowance Valuation allowance Deferred Tax Assets, Valuation Allowance Goodwill and Other Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] International equities [Member] Defined Benefit Plan, Equity Securities, Non-US [Member] Buildings [Member] Building [Member] JacksonvilleFL [Member] JacksonvilleFL [Member] JacksonvilleFL [Member] Business Segments Segment Reporting Disclosure [Text Block] Liquidation Period [Axis] Liquidation Period [Axis] Liquidation Period [Axis] Schedule of Goodwill [Table] Goodwill [Table] Schedule of Amounts Recognized in Balance Sheet Schedule of Amounts Recognized in Balance Sheet [Table Text Block] Fair value of assets at beginning of year Fair value of assets at end of year Fair Value Defined Benefit Plan, Plan Assets, Amount U.S. Federal, Current Current Federal Tax Expense (Benefit) Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Amortized Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Schedule of Net (Benefit) Costs Schedule of Net Benefit Costs [Table Text Block] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Contingent consideration liabilities Business Combination, Contingent Consideration, Liability Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Number of shares authorized to be repurchased Share Repurchase Program, Authorized, Number of Shares Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Letter of credit sublimit Line of Credit Facility Sublimit, Current Borrowing Capacity Amount of current borrowing capacity under the credit facility sublimit considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. Leases Lessee, Leases [Policy Text Block] Amortization of intangible assets Amortization of Intangible Assets Amortization of Intangible Assets Restricted cash Restricted Cash and Cash Equivalent, Current Deferred Income Taxes Deferred Income Tax Assets, Net Summary of Changes in Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Share-Based Compensation Arrangement by Share-Based Payment Award, Award other than Options, Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Award other than Options, Grants in Periods, Grante Date Fair Value The grant-date fair value of stock awards granted during the reporting period as calculated by applying the disclosed pricing methodology. Number of business lines Number of Business Lines The number of business lines. Settlement gain Settlement Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement Other Comprehensive Income (Loss), Before Tax Other Comprehensive Income (Loss), before Tax [Abstract] Mander Portman Woodward [Member] Mander Portman Woodward [Member] Mander Portman Woodward Allowance for Credit Losses Accounts Receivable [Policy Text Block] Foreign income tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Settlement of Advance to Affiliate Settlement of Advance to Affiliate Non-cash exchange from advancing money to an affiliate (an entity that is related but not strictly controlled by the entity) Total finance lease liabilities Finance Lease, Liability Arrangement Duration Trading Arrangement Duration Operating losses of acquired companies since acquisition date Business Combination, Acquiree's Earnings (Loss) since Acquisition Date, Actual 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] Segments [Axis] Segments [Axis] Segments [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Acquisitions Defined Benefit Plan, Benefit Obligation, Business Combination Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Contract Asset, Noncurrent Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent Other Payment for (Proceeds from) Other Investing Activity Other Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Number of Restaurants Number of Restaurants Five-Year Credit Agreement [Member] Five-Year Credit Agreement [Member] Five-Year Credit Agreement Assets Assets [Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Supplier Finance Program Reconciliation Supplier Finance Program [Table Text Block] Debt Instrument [Axis] Debt Instrument [Axis] 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 Pensions and Other Postretirement Plans Retirement Benefits [Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Business Combination [Line Items] Business Combination [Line Items] Executive Officer Executive Officer [Member] 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 Repurchase of Class B common stock Treasury Stock, Value, Acquired, Cost Method Deferred Revenue Deferred Revenue Investment, Name [Axis] Investment, Name [Axis] Interest rate Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Lease Liabilities Operating lease, liability, noncurrent Operating Lease, Liability, Noncurrent Entity Voluntary Filers Entity Voluntary Filers Management Services Management Services Expense Amount of expense for management and operating services Right to elect Board of Directors percentage Right To Elect Board Of Directors Percentage Right To Elect Board Of Directors Percentage Accounts receivable Accounts Receivable, after Allowance for Credit Loss Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Entity Registrant Name Entity Registrant Name 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). Prior service (cost) credit Current year prior service (credit) cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Net pension benefit, settlement gain and early retirement and separation program costs Total (Benefit) Cost for the Year Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Accrued Compensation and Related Benefits Deferred Compensation Liability, Classified, Noncurrent Income Taxes [Table] Income Taxes [Table] -- None. No documentation exists for this element. -- Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Schedule of Non-Operating (Expense) Income [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Recipient of Consideration [Domain] Recipient of Consideration [Domain] [Domain] for Recipient of Consideration Supplier Finance Program, Obligation, Statement of Financial Position [Extensible Enumeration] Supplier Finance Program, Obligation, Statement of Financial Position [Extensible Enumeration] 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. Principal payments of finance leases Finance Lease Payments Amount of cash outflow for payments on finance lease. Cost method investments Equity Securities without Readily Determinable Fair Value, Amount After 2030 [Member] Loss Carryforwards Expirations Range Two [Member] -- None. No documentation exists for this element. -- Machinery, Equipment and Fixtures [Member] Machinery and Equipment [Member] Interest cost Defined Benefit Plan, Interest Cost 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 Related Party [Axis] Related and Nonrelated Parties [Axis] Adjustment for sale of a business with foreign operations Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Retransmission Revenue [Member] Retransmission Revenue [Member] Retransmission Revenue [Member] Services [Member] Service [Member] Restatement Determination Date: Restatement Determination Date [Axis] Supplier Finance Program [Table] Supplier Finance Program [Table] Non-U.S., Deferred Deferred Foreign Income Tax Expense (Benefit) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Noncontrolling interest capital contributions Noncontrolling Interest, Increase from Subsidiary Equity Issuance Income Tax Expense (Benefit), Continuing Operations [Abstract] Income Tax Expense (Benefit), Continuing Operations [Abstract] Other Proceeds from (Payment for) Other Financing Activity Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Net amount reclassified from accumulated other comprehensive income Reclassifications, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Voluntary Retirement Incentive Program [Member] Voluntary Retirement Incentive Program [Member] Voluntary retirement incentive program Name Trading Arrangement, Individual Name Cash flow hedges (loss) gain Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Alphabet And Berkshire Hathaway Common Stock [Member] Alphabet And Berkshire Hathaway Common Stock [Member] Alphabet and Berkshire Hathaway Common Stock [Member] Kaplan Stock Option [Member] Kaplan Stock Option [Member] -- None. No documentation exists for this element. -- Long-term Purchase Commitment, Amount Long-Term Purchase Commitment, Amount Management Services Management Services [Member] Management Services Purchase of redeemable noncontrolling interest Noncontrolling interest, decrease from redemptions or purchase of interests Noncontrolling interest, decrease from redemptions or purchase of interests Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Unsecured fixed-rate notes, face amount Debt Instrument, Face Amount Kaplan International [Member] Kaplan International [Member] Kaplan International [Member] Mandatorily redeemable noncontrolling interest Effective Income Tax Rate Reconciliation, Mandatorily Redeemable Noncontrolling Interest Change in Fair Value Amount Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to the change in fair value of mandatorily redeemable noncontrolling interest. Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Revenue Source [Domain] Revenue Source [Domain] [Domain] for Revenue Source [Axis} 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. Deferred tax liability (asset) Defined Benefit Plan Accumulated Other Comprehensive Income Tax Tax recorded on the defined benefit plan accumulated other comprehensive income. Equity funds [Member] Equity Funds [Member] Denominator: Denominator [Abstract] Denominator Name Awards Close in Time to MNPI Disclosures, Individual Name Beginning of year, Average Grant-Date Fair Value (in dollars per share) End 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 Cash flow hedges AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax 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 Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Other, net Other Nonoperating Gains (Losses) 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. ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag 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. Amortization of unearned stock compensation and stock option expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Impairment of cost method investments Impairment of cost method investments Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount Business Combinations Business Combinations and Other Purchase of Business Transactions, Policy [Policy Text Block] Options outstanding exercisable now (shares) Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Exercisable Now Options outstanding exercisable now. 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). Short-term investment funds [Member] Fixed Income Funds [Member] Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss) before Reclassifications, Tax AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] Liability Class [Axis] Liability Class [Axis] non-U.S. [Member] Foreign Tax Jurisdiction [Member] Auditor Firm ID Auditor Firm ID Deferred state income tax asset State income tax loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards, State and Local Segment [Domain] Segments [Domain] Markel Corporation [Member] MarkelCorporation [Member] Markel Corporation [Member] Non-U.S. Income (Loss) from Continuing Operations before Income Taxes, Foreign Defined Benefit Plans [Member] Defined Benefit Plans [Member] Defined benefit plans consisting of various pension plans and a Supplemental Executive Retirement Plan (SERP). Benefit obligation at begining of year Benefit obligation at end of year Defined Benefit Plan, Benefit Obligation Fair Value Hierarchy and NAV [Domain] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Additional Investment in Equity Method Investments Additional Investment in Equity Method Investments The cash outflow and other consideration given associated with the purchase of or advances to an 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. Inventories Increase (Decrease) in Inventories Schedule of New Accounting Pronouncements and Changes in Accounting Principles Accounting Standards Update and Change in Accounting Principle [Table Text Block] Less: accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Basis of Presentation and Principles of Consolidation Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Loan to related party Payments for Advance to Affiliate Payments for Advance to Affiliate Preferred Stock, $1 par value; 977,000 shares authorized, none issued Preferred Stock, Value, Issued Other liabilities Business Combination, Recognized Liability Assumed, Liability All Executive Categories All Executive Categories [Member] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Finished goods Inventory, Finished Goods, Net of Reserves Common stock Common Stock, Value, Issued Finance lease assets Finance Lease, Right-of-Use Asset, after Accumulated Amortization Equity in (earnings) losses of affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits, by Title of Individual [Axis] Title and Position [Axis] Floor plan interest expense Floor plan interest expense Interest expense incurred on vehicle floor plan payable outstanding during the period. Commitments and Contingencies (Note 18) Commitments and Contingencies Equity Method Investment, Diluted Ownership Percentage Equity Method Investment, Diluted Ownership Percentage Equity Method Investment, Diluted Ownership Percentage Investments in Marketable Securities Investments in Marketable Securities Amount of investment for purchase of marketable security. Amortized intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Finite-Lived Fair Value Measured at Net Asset Value Per Share [Member] Fair Value Measured at Net Asset Value Per Share [Member] Network affiliation agreements [Member] Contract-Based Intangible Assets [Member] Business Combination [Axis] Business Combination [Axis] Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Other indebtedness Other Long-Term Debt Noncontrolling Interest [Member] Noncontrolling Interest [Member] Net (loss) gain on cost method investments Equity Securities without Readily Determinable Fair Value, Net Upward (Downward) Price Adjustment, Annual Amount Amount of gain/(loss) from upward/(downward) price adjustment on investment in equity security without readily determinable fair value. Number of contingently issuable shares Number of contingently issuable shares Number of contingently issuable shares in stock award Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Supplemental Executive Retirement Plan (SERP) [Member] Supplemental Employee Retirement Plan [Member] Investments in Affiliates Equity Method Investments [Policy Text Block] Valuation Allowance [Line Items] Valuation Allowance [Line Items] 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. Other Comprehensive Income (Loss) [Line Items] Other Comprehensive Income (Loss) [Line Items] [Line Items] for Other Comprehensive Income (Loss) [Table] Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Total Assets [Member] Assets, Total [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Percentage of total plan assets Defined Benefit Plan Assets Allocation (Percent) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Expired or forfeited, Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period Capital Term Loan maturing in 2028 [Member] Capital Term Loan maturing in 2028 [Member] Capital Term Loan maturing in 2028 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 Promissory Note for CSI Minority Shares due 2026 [Member] Promissory Note for CSI Minority Shares due 2026 [Member] Promissory Note for CSI Minority Shares due 2026 Defined Benefit Plan Assets Total [Member] Defined Benefit Plan Assets Total [Member] -- None. No documentation exists for this element. -- Operating Revenues Revenue from Contract with Customer [Abstract] Fair value of debt instrument Debt Instrument, Fair Value Disclosure FCC licenses [Member] Operating and Broadcast Rights [Member] Schedule of Unrecognized Tax Benefits Roll Forward Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Number of multiemployer plans contributed to Number Of Multiemployer Plans Contributed To Number of multiemployer pension plans to which the Company contributed. 2030 Defined Benefit Plan, Expected Future Benefit Payment, Year Five All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Transferred at Point in Time [Member] Transferred at Point in Time [Member] Name Forgone Recovery, Individual Name Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Capital Stock, Stock Awards And Stock Options Capital Stock, Stock Awards And Stock Options [Text Block] -- None. No documentation exists for this element. -- N2K Networks [Member] N2K Networks [Member] N2K Networks Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Supplemental Education [Member] Supplemental Education [Member] Supplemental Education Concentration in single marketable equity security [Member] Concentration in single marketable equity security [Member] Concentration in single marketable equity security 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 Change in capitalized contract cost, other Change in Capitalized Contract Cost, Other Change in capitalized contract cost, other Foreign currency exchange rate changes Goodwill, Foreign Currency Translation, Gain (Loss) 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] Other current investments Other Short-Term Investments Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Schedule of Finite-Lived Intangible Assets [Table] Intangible Asset, Finite-Lived [Table] Supplier Finance Program [Domain] Supplier Finance Program [Domain] Investment Managers [Domain] Investment Managers [Domain] [Domain] for Investment Managers [Axis] Number of performance obligations with variable consideration number of performance obligations with variable consideration number of performance obligations with variable consideration Geographical [Axis] Geographical [Axis] Supplemental Education [Member] Test Preparation [Member] Test Preparation [Member] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Transaction Type [Axis] Transaction Type [Axis] Other assets and other liabilities, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] 2031 and after [Member] Loss Carry Forwards Expirations After Year Five [Member] Loss Carry Forwards Expirations After Year Five Member Manufacturing [Member] Manufacturing [Member] Manufacturing business Income tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards Operating revenues Business Combination, Pro Forma Information, Pro Forma Revenue Foreign exchange loss (gain) Foreign currency (loss) gain, net Gain (Loss), Foreign Currency Transaction, before Tax SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] Deferred revenue Deferred Revenue, Current Loan Receivable Fixed Interest Rate Related Party Transaction, Rate Non-U.S.deferred tax asset related to capital loss carryforwards Capital loss carryforwards Deferred Tax Assets, Capital Loss Carryforwards Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Monte Carlo Monte Carlo [Member] Monte Carlo Income Tax Expense (Benefit), Adjustment of Deferred Tax (Asset) Liability Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Title of 12(b) Security Title of 12(b) Security Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Changes in fair value Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Gain (Loss), Changes in Fair Value Amount of gain (loss) recognized in income due to changes in fair value from liability measured at fair value on recurring basis using unobservable input (level 3). Costs amortized during the period Capitalized Contract Cost, Amortization Unrealized gain on marketable equity securities Deferred Tax Liabilities, Unrealized Gains on Marketable Equity Securities Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains on marketable equity securities. Per Share Information Attributable to Graham Holdings Company Common Stockholders Earnings Per Share [Abstract] Penalties accrued related to unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties Accrued Operating lease payments due in 2030 Lessee, Operating Lease, Liability, to be Paid, Year Five Ownership percentage by parent Ownership percentage by parent Subsidiary, Ownership Percentage, Parent Proceeds from Equity Method Investment, Distribution, Return of Capital Proceeds from Equity Method Investment, Distribution, Return of Capital Real Estate Term Loan maturing in 2028 [Member] Real Estate Term Loan maturing in 2028 [Member] Real Estate Term Loan maturing in 2028 Antidilutive Weighted Average Restricted Stock Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Carryforward amount Tax Credit Carryforward, Amount Dispositions Goodwill, Written off Related to Sale of Business Unit Deferred Income Tax Liabilities [Line Items] Deferred Income Tax Liabilities [Line Items] [Line Items] for Deferred Income Tax Liabilities [Table] 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] Actuarial gain Current year actuarial (gain) loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Shares repurchased by Company Treasury Stock, Shares, Acquired Finance lease payments due thereafter Finance Lease, Liability, to be Paid, after Year Five 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 Award Timing Disclosures [Line Items] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Early Retirment Program Expense [Axis] Early Retirment Program Expense [Axis] -- None. No documentation exists for this element. -- Schedule of Inventories and Contracts in Progress Schedule of Inventory, Current [Table Text Block] Service cost Pension service cost Defined Benefit Plan, Service Cost Gain on marketable equity securities Gain (Loss) on Securities [Table Text Block] Measurement Frequency [Domain] Measurement Frequency [Domain] Unfunded Commitment Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments CDJR [Member] CDJR [Member] CDJR automotive dealership Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Non-employee Director [Member] Non-employee Director [Member] Non-employee Director State and Local, Deferred Deferred State and Local Income Tax Expense (Benefit) Weighted average interest rate Average annual interest rate of borrowings Debt Instrument, Interest Rate During Period Net Income Attributable to Graham Holdings Company Common Stockholders Net income attributable to Graham Holdings Company common stockholders Net Income (Loss) Attributable to Parent Remaining GHC One and GHC Two [Member] Remaining GHC One and GHC Two [Member] Remaining GHC One and GHC Two Interest rate swaps Interest Rate Cash Flow Hedge Liability at Fair Value Construction in Progress [Member] Construction in Progress [Member] Other accrued liabilities Other Accrued Liabilities, Current Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities, Current [Abstract] Accounts Payable and Accrued Liabilities, Current [Abstract] Vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Deductions SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred Stock, Shares Authorized Preferred Stock, Shares Authorized Common shares repurchased Cost of shares repurchased by Company, including commissions and excise taxes Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Reclassifications Reclassification, Comparability Adjustment [Policy Text Block] Prepaid pension cost Deferred Tax Liabilities, Prepaid Expenses Contract Asset, Total Contract with Customer, Asset, after Allowance for Credit Loss Goodwill and other intangible assets Deferred Tax Liabilities, Goodwill and Intangible Assets Student and Customer Relationships [Member] Customer Relationships [Member] Income from Operations Operating Income (Loss) Retained earnings Retained Earnings (Accumulated Deficit) Schedule of Obligation, Asset and Funding Information Schedule of Net Funded Status [Table Text Block] Percentage Of Refundable Amounts Included Within Contract Liabilities Percentage Of Refundable Amounts Included Within Contract Liabilities Percentage Of Refundable Amounts Included Within Contract Liabilities. Accrual balance related to stock based compensation Deferred Compensation Share-Based Arrangements, Liability, Current and Noncurrent Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Transferred over Time [Member] Transferred over Time [Member] Impairment of intangible assets Impairment of Intangible Assets, Indefinite-Lived (Excluding Goodwill) Curtailment Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment Class of Stock [Axis] Class of Stock [Axis] Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Net (repayments of) 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. Impairment of intangible assets Impairment of Intangible Assets, Finite-Lived Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Transaction [Axis] Transaction [Axis] Transaction [Axis] Irrevocable Group Annuity Contract Purchase [Member] Irrevocable Group Annuity Contract Purchase [Member] Irrevocable Group Annuity Contract Purchase [Member] Other Deferred Tax Liabilities, Other Inventories and contracts in progress Inventories and contracts in progress Inventory, Net of Allowances, Customer Advances and Progress Billings Retirement Plan Type [Axis] Retirement Plan Type [Axis] Other (expense) income, net Total Other Non-Operating (Expense) Income Other (expense) income, net Other Nonoperating Income (Expense) Statement [Table] Statement [Table] Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Accounts receivable, noncurrent Accounts Receivable, after Allowance for Credit Loss, Noncurrent Provision for deferred income taxes Total income tax, Deferred Deferred Income Tax Expense (Benefit) Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Decreases due to lapse of applicable statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Cash Flows from Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Foreign Tax Jurisdiction, Other [Member] Foreign Tax Jurisdiction, Other [Member] Variable Rate [Domain] Variable Rate [Domain] Finance lease, liability, noncurrent Finance Lease, Liability, Noncurrent Net proceeds from sales of businesses, property, plant and equipment, investments 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. Exercise Price $427 [Member] Exercise Price $427 [Member] Exercise Price of $427 Cash overdrafts Bank Overdrafts Kaplan, Graham Media Group, Leaf Group, Code3 and Pinna [Member] Kaplan, Graham Media Group, Leaf Group, Code3 and Pinna [Member] Kaplan, Graham Media Group, Leaf Group, Code3 and Pinna Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Valuation allowance on tax credit carryforward Tax Credit Carryforward, Valuation Allowance Amendment Flag Amendment Flag Shares reserved for stock awards granted under the plan Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Allocation of the Assets of the Company's Pension Plans Schedule of Allocation of Plan Assets [Table Text Block] Other Postretirement Plans [Member] Other Postretirement Benefits Plan [Member] Cost of 15,639,057 and 15,667,693 shares of Class B common stock held in treasury Treasury Stock, Common, Value Termination Date Trading Arrangement Termination Date Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Cash and Cash Equivalents Cash and Cash Equivalents, Unrestricted Cash and Cash Equivalents, Policy [Policy Text Block] Raw materials Inventory, Raw Materials, Net of Reserves Share-Based Payment Arrangement, Third Tranche [Member] Share-Based Payment Arrangement, Tranche Three [Member] Indefinite-lived intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Indefinite-Lived Operating lease, weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Activity Related to Stock Options Share-Based Payment Arrangement, Option, Activity [Table Text Block] Revenues of acquired companies since acquisition date Business Combination, Acquiree's Revenue since Acquisition Date, Actual Fair Value, Assets Measured on Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Basic average number of common shares outstanding (in shares) Weighted average shares outstanding (shares) Weighted Average Number of Shares Outstanding, Basic Unrecognized tax benefit that would impact the effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Summary of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Options Exercisable, Shares Exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Exercise Price Range [Domain] Exercise Price Range [Domain] Segment Reporting [Abstract] Segment Reporting [Abstract] Amortization of Intangible Assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Cost of Revenue Cost of Revenue Early retirement and separation program costs Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits Berkshire Hathaway [Member] Berkshire Hathaway [Member] Berkshire Hathaway Debt Disclosure [Abstract] Debt Disclosure [Abstract] Defined Benefit Plan by Plan Asset Categories [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Market value of Company's stock (in dollars per share) Common Stock Stated Market Value Per Share Common Stock Stated Market Value Per Share Reclassification from AOCI, Current Period, Tax Provision for income taxes Reclassification from AOCI, Current Period, Tax Net borrowings (payments) under revolving credit facilities Proceeds from (Repayments of) Lines of Credit Document Financial Statement Restatement Recovery Analysis [Flag] Document Financial Statement Restatement Recovery Analysis [Flag] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Common Stock, Par or Stated Value Per Share Common Stock, Par or Stated Value Per Share Cumulative Payments For Advance to Affiliate Cumulative Payments For Advance to Affiliate The cumulative cash outflow from advancing money to an affiliate (an entity that is related but not strictly controlled by the entity). 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. Income taxes receivable Income Taxes Receivable, Current 2031-2035 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Less: Net gains in earnings from marketable equity securities sold and donated Equity Securities, FV-NI, Realized Gain (Loss) Number of shares granted Granted, Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Use of Estimates Use of Estimates, Policy [Policy Text Block] Deferred Tax Valuation Allowance [Member] SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] Current liability Liability, Defined Benefit Plan, Current Operating cash flows from finance leases Finance Lease, Interest Payment on Liability Gain on cost method investments Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Insider Trading Arrangements [Line Items] Foreign Investments [Member] Foreign Investments [Member] Information about the entity's defined pension plan foreign investments. Equity securities [Member] Equity Securities [Member] Total Liabilities Liabilities Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Finance lease payments due in 2030 Finance Lease, Liability, to be Paid, Year Five Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Increases related to current year tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Purchase of equity from noncontrolling interest Purchase of equity from noncontrolling interest Purchase of equity from noncontrolling interest Trade Names and Trademarks [Member] Trademarks and Trade Names [Member] Estimated employer contributions in next fiscal year Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Total net lease cost Lease Cost Net of Sublease Income Amount of lease cost, net of sublease income, recognized by lessee for lease contract 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. Other Deferred Tax Assets, Tax Deferred Expense, Other Consolidation Items [Axis] Consolidation Items [Axis] Variable Rate [Axis] Variable Rate [Axis] Counterparty Name [Axis] Counterparty Name [Axis] Intersection [Member] Intersection [Member] Intersection Holdings,LLC [Member] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Recognized asset (liability) Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Mandatorily Redeemable Noncontrolling Interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Noncurrent VIRGINIA MARYLAND