Accounts receivable, net Accounts receivable, net Accounts and Other Receivables, Net, Current Undistributed (Loss) 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. Purchase of noncontrolling interest Payments for Repurchase of Redeemable Noncontrolling Interest Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Repayments of borrowings Repayments of Long-Term Debt Amortization of Intangible Assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Cover [Abstract] Cover [Abstract] Net Decrease in Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Advance Related To Kaplan University Transaction Advance Related To Kaplan University Transaction Advance Related To Kaplan University Transaction Schedule of Indefinite-Lived Intangible Assets [Table] Intangible Asset, Indefinite-Lived [Table] Percentage of interest acquired Business Acquisition, Percentage of Voting Interests Acquired Trading Symbol Trading Symbol Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Less: Net gains in earnings from marketable equity securities sold and donated Equity Securities, FV-NI, Realized Gain (Loss) Equity Securities, FV-NI, Realized Gain (Loss) Comprehensive (Loss) Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Non-NEOs Non-NEOs [Member] Reportable Subsegments [Member] Reportable Subsegments [Member] Dividends declared per common share Common Stock, Dividends, Per Share, Declared Investment Manager 2 [Member] Investment Manager 2 [Member] Investment Manager 2 [Member] Distribution to noncontrolling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Accounts receivable, net Accounts receivable Increase (Decrease) in Accounts Receivable Gain on marketable equity securities, net Gain on marketable equity securities, net Equity Securities, FV-NI, Gain (Loss) Operating Costs and Expenses Operating Costs and Expenses [Abstract] 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. Organization, Consolidation and Presentation of Financial Statements Disclosure Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Cash flow hedges AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] 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. Fair Value Measurements Fair Value Disclosures [Text Block] Proceeds from exercise of stock options Proceeds from Stock Options Exercised Other Comprehensive Loss, Before Tax Other Comprehensive Income (Loss), before tax Other Comprehensive Income (Loss), before Tax Award Timing Disclosures [Line Items] Investment, Name [Domain] Investment, Name [Domain] 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. Contract costs capitalized during the period Contract Costs Capitalized During the Period Capitalized contract costs associated with new contracts entered into during the period. Undistributed (loss) earnings Undistributed Earnings, Basic Proceeds from sales of marketable equity securities Proceeds from Sale and Maturity of Marketable Securities 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 Operating Revenues Revenue from Contract with Customer [Abstract] U.S. [Member] UNITED STATES Deferred Charges and Other Assets Other Assets, Noncurrent Gross Carrying Amount Finite-Lived Intangible Assets, Gross Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] World of Good Brands [Member] World of Good Brands [Member] World of Good Brands Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] 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] Supplier Finance Program [Domain] Supplier Finance Program [Domain] Operating Segments [Member] Operating Segments [Member] Contracts in progress Inventory for Long-Term Contracts or Programs, Gross Net Cash Provided by Operating Activities Net Cash Provided by Operating Activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Summary of Changes in Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Other Stockholders' Equity, Other Prepaid expenses Prepaid Expense, Current Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets Amount of other assets acquired at the acquisition date. Redeemable noncontrolling interest Redeemable noncontrolling interest Redeemable Noncontrolling Interest, Equity, Other, Fair Value Award Timing Method Award Timing Method [Text Block] Deferred Revenue, Period Decrease Percentage Deferred Revenue, Period Increase (Decrease) Percentage Deferred Revenue, Period Increase (Decrease) Percentage Dekko [Member] Dekko [Member] Dekko member Net pension benefit, early retirement programs and special separation benefit expense Net Periodic Cost (Benefit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 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. Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Vehicle Floor Plan Facility [Member] Higher Education [Member] Higher Education [Member] Higher Education [Member] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Insider Trading Policies and Procedures [Line Items] Loans Payable to Bank Loans Payable to Bank Other Indebtedness [Member] Other Indebtedness [Member] Other Indebtedness [Member] Use of Estimates in the Preparation of the Condensed Consolidated Financial Statements Use of Estimates, Policy [Policy Text Block] Adjustment to Compensation, Amount Adjustment to Compensation Amount Compensation Amount Outstanding Recovery Compensation Amount CARES Act Fund [Axis] CARES Act Fund [Axis] CARES Act Fund 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] Transaction Type [Axis] Transaction Type [Axis] Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Entity Small Business Entity Small Business Company Selected Measure Amount Company Selected Measure Amount Interest Rate on Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Interest Rate on Advance to Minority Shareholder Clyde's Restaurant Group [Member] Clyde's Restaurant Group [Member] Clyde's Restaurant Group Tabular List, Table Tabular List [Table Text Block] Level 3 Fair Value, Inputs, Level 3 [Member] Mary Free Bed at Home [Member] Residential And Michigan Hospital Joint Venture [Member] Residential and a Michigan hospital joint venture [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Antidilutive securities, shares Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Goodwill, Net Goodwill Goodwill, net, beginning balance Goodwill, net, ending balance Goodwill FCC licenses [Member] Operating and Broadcast Rights [Member] Estimated credit losses Accounts Receivable, Allowance for Credit Loss Inventories and Contracts in Progress Inventory Disclosure [Text Block] Early Retirement Program Expense [Domain] Early Retirement Program Expense [Domain] -- None. No documentation exists for this element. -- Acquisition of noncontrolling interest Noncontrolling Interest, Increase from Business Combination Fixed income securities [Member] Fixed Income Securities [Member] Stock Option Plan [Member] Stock Option Plan [Member] Share-Based Payment Arrangement, Option [Member] Depreciation of property, plant and equipment Depreciation Other Proceeds from (Payments for) Other Financing Activities Total Comprehensive (Loss) Income Attributable to Graham Holdings Company Comprehensive Income (Loss), Net of Tax, Attributable to Parent Defined Benefit Pension Plan [Member] Defined Benefit Pension Plans [Member] Pension Plan [Member] Income taxes payable Accrued Income Taxes, Current Number of investment companies actively managing plan assets Number Of Investment Companies Managing Plan Assets The number of investment companies actively managing plan assets. Government Relief, CARES Act Government Relief, CARES Act Amount received from the government as relief under the CARES Act Percent allocated to common stockholders (1) Percentage Of Undistributed Earnings Allocated To Common Stockholders Represents the percentage allocation of undistributed earnings to common stockholders. Award Type [Axis] Award Type [Axis] Foreign currency exchange rate changes Goodwill, Foreign Currency Translation Gain (Loss) Secured Overnight Financing Rates (SOFR) [Member] Secured Overnight Financing Rates (SOFR) [Member] Secured Overnight Financing Rates (SOFR) Pinna [Member] Pinna [Member] Pinna Work-in-process Inventory, Work in Process, Net of Reserves Property, Plant and Equipment, Net Property, Plant and Equipment, Net Total Liabilities Liabilities Noncontrolling Interests Equity, Attributable to Noncontrolling Interest Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Expiration Date Trading Arrangement Expiration Date Cash Flows from Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Number of Shares Held in Investment Investment Owned, Balance, Shares Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable And Accrued Liabilities Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable And Accrued Liabilities [Text Block] The entire disclosure of Accounts Receivable, Accounts Payable, Vehicle Floor Plan Payable And Accrued Liabilities Current portion of lease liabilities Operating Lease, Liability, Current Total Shareholder Return Amount Total Shareholder Return Amount Other current investments Other Short-Term Investments Recipient of Consideration [Axis] Recipient of Consideration [Axis] Recipient of Consideration Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Unrealized gain on pensions and other postretirement plans Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Error Correction [Table] Commercial note with Truist Bank maturing in 2032 - $27.2 million [Member] Commercial note with Truist Bank maturing in 2032 - $27.2 million [Member] Commercial note with Truist Bank maturing in 2032 - $27.2 million Term Loan, Unused Borrowing Capacity, Amount Debt Instrument, Unused Borrowing Capacity, Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] 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. 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. -- Diluted average number of common shares outstanding (in shares) Denominator for diluted (loss) earnings per share (shares) Weighted Average Number of Shares Outstanding, Diluted MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Total Common Stockholders’ Equity Equity, Attributable to Parent Cost of Class B common stock held in treasury Treasury Stock, Value Issuance of borrowings Proceeds from Issuance of Debt Vehicle Floor Plan Facility - New Vehicles [Member] Vehicle Floor Plan Facility - New Vehicles [Member] Vehicle Floor Plan Facility - New Vehicles Type of Adoption [Domain] Accounting Standards Update [Domain] Changes in Carrying Amount of Goodwill Schedule of Goodwill [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 Concentration Risk Type [Domain] Concentration Risk Type [Domain] New Accounting Pronouncements or Change in Accounting Principle [Table] Accounting Standards Update and Change in Accounting Principle [Table] Selling, General and Administrative Expense Selling, General and Administrative Expense Realm [Member] Realm [Member] Investment in Realm Goods [Member] Product [Member] Number of Automotive Dealerships Owned Number of Automotive Dealerships Owned Number of Automotive Dealerships Owned Document Fiscal Period Focus Document Fiscal Period Focus All Executive Categories All Executive Categories [Member] Add: Effect of dilutive stock options (shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Net income attributable to noncontrolling interest Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable Real Estate Term Loan maturing in 2028 - $75.2 million [Member] Real Estate Term Loan maturing in 2028 - $75.2 million [Member] Real Estate Term Loan maturing in 2028 - $75.2 million Equity Securities [Member] Equity Securities [Member] Estimated amortization of intangible assets, 2026 Finite-Lived Intangible Asset, Expected Amortization, Year Two Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Goodwill expected to be deductible for income tax purposes Business Acquisition, Goodwill, Expected Tax Deductible Amount Assets Assets [Abstract] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Other Comprehensive 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 Document Type Document Type U.S. equities [Member] Defined Benefit Plan, Equity Securities, US [Member] Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Framebridge [Member] Framebridge [Member] Framebridge Summary of Segment Reporting Information, by Operating Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Investments in equity affiliates, 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 redeemable noncontrolling interest 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. Purchases of marketable equity securities Payments to Acquire Marketable Securities Payments to Acquire Marketable Securities Business Combination, Pro Forma Information, (Loss) of acquired compnies since acquisition date Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual GBP revolving credit facility borrowings [Member] GBP revolving credit facility borrowings [Member] GBP revolving credit facility borrowings Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Contract with Customer, Liability Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Debt Instrument, Periodic Payment, Principal Debt Instrument, Periodic Payment, Principal KIHL [Member] KIHL [Member] KIHL [Member] Maximum [Member] Maximum [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Accumulated impairment losses, beginning balance Accumulated impairment losses, ending balance Goodwill, Impaired, Accumulated Impairment Loss Amortized Intangible Assets, Net Net Carrying Amount Finite-Lived Intangible Assets, Net Antidilutive Securities [Axis] Antidilutive Securities [Axis] Accounts payable Accounts Payable, Current Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Statistical Measurement [Axis] Statistical Measurement [Axis] Obligations outstanding related to floor plan facilities associated with new vehicles Supplier Finance Program, Obligation Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] (Loss) Income Before Income Taxes (Loss) Income Before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Allegheny Health Network (AHN) Healthcare at Home [Member] CelticHealthcareAlleghenyHealthNetworkJointVenture [Member] A joint venture formed between Celtic Healthcare and Allegheny Health Network Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Acquisitions And Dispositions [Abstract] Acquisitions And Dispositions [Abstract] Acquisitions and Dispositions Other Comprehensive Loss, Before Tax Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Name Outstanding Recovery, Individual Name Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Impairment of goodwill Impairment Goodwill, Impairment Loss Antidilutive Weighted Average Restricted Stock and Options Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Money Market Investments Money Market Funds, at Carrying Value Award Timing Predetermined Award Timing Predetermined [Flag] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Translation adjustments arising during the period Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Investment, Name [Axis] Investment, Name [Axis] Student and Customer Relationships [Member] Customer Relationships [Member] Transaction Type [Domain] Transaction Type [Domain] Transaction Type [Domain] Amortization of prior service cost (credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Diluted net (loss) income per common share (in USD per share) Diluted (loss) income per common share (in usd per share) Earnings Per Share, Diluted Programs to Cease New Enrollments, Number Programs to Cease New Enrollments, Number Programs to Cease New Enrollments, Number Counterparty Name [Domain] Counterparty Name [Domain] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Ownership [Axis] Ownership [Axis] Foreign exchange loss (gain) Foreign currency (loss) gain, net Gain (Loss), Foreign Currency Transaction, before Tax Kaplan Singapore Kaplan Singapore [Member] Kaplan Singapore Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Floor plan assistance Vehicle Floor Plan Facility Assistance The amount of assistance received from the manufacturers recognized as a reduction of operating expenses. Interest Rate Swaps Interest Rate Cash Flow Hedge Asset at Fair Value Net (Loss) Income Net (Loss) Income Net Income Net of Tax Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Inventory Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Provision for Income Taxes Income Tax Expense (Benefit) Interest cost Defined Benefit Plan, Interest Cost Purdue University Global [Member] Purdue University Global [Member] Purdue University Global Derivative, Notional Amount Derivative, Notional Amount Total fixed interest rate of debt Long-Term Debt, Percentage Bearing Fixed Interest, Percentage Rate 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". Operating Revenues Revenue from Contract with Customer, Excluding Assessed Tax Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Advances to Affiliate Advance to Minority Shareholder Advance to Minority Shareholder Gross unrealized gains Equity Securities FV-NI, Accumulated Gross Unrealized Gain Amount of unrealized gain on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities Franchise Agreements [Member] Franchise Rights [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Term Loan maturing in 2027 - $150 million [Member] Term Loan maturing in 2027 - $150 million [Member] Term Loan maturing in 2027 - $150 million Kaplan University Transaction [Member] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Programs Still Offered, Number Programs Still Offered, Number Programs Still Offered, Number Other Other Operating Activities, Cash Flow Statement All Adjustments to Compensation All Adjustments to Compensation [Member] Accrued compensation and related benefits Employee-related Liabilities, Current Capital in excess of par value Additional Paid in Capital Summary of other non-operating income Schedule of Other Nonoperating Income (Expense) [Table Text Block] Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Interest Expense, Net Interest Income (Expense), Nonoperating Legal Entity [Axis] Legal Entity [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Issuance of Class B common stock, net of restricted stock award forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Cash Flow Hedges [Member] Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Entity Address, State or Province Entity Address, State or Province Change in redemption value of redeemable noncontrolling interest Noncontrolling Interest, Change in Redemption Value Non-operating pension and postretirement benefit income, net Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Amortization of net prior service (credit) cost included in net income Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Liabilities and Equity Liabilities and Equity [Abstract] Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Loan Receivable Fixed Interest Rate Related Party Transaction, Rate Restatement Determination Date Restatement Determination Date Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Lease Right-of-Use Assets Operating Lease, Right-of-Use Asset Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Dividends declared Dividends Payable, Current Net Prior Service (Credit) Cost [Member] Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Total Financial Liabilities Financial Liabilities Fair Value Disclosure Curtailment gain Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment (Loss) Earnings Per Share Earnings Per Share [Text Block] Subsequent Event [Member] Subsequent Event [Member] Restricted cash Restricted Cash and Cash Equivalents, Current Subsegments [Domain] Subsegments [Domain] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Minimum Term of Contract Minimum Term of Contract Minimum Term of Contract Segments [Domain] Segments [Domain] Income tax benefit related to items of other comprehensive loss Other Comprehensive Income (Loss), income tax Other Comprehensive Income (Loss), Tax Trade Names and Trademarks [Member] Trademarks and Trade Names [Member] PEO PEO [Member] Name Trading Arrangement, Individual Name Kaplan Corporate and Other [Member] Kaplan Corporate and Other [Member] Kaplan Corporate And Other [Member] Equity in earnings (losses) of affiliates, net Income (Loss) from Equity Method Investments Contingent consideration liabilities [Member] Contingent consideration liabilities [Member] Contingent consideration liabilities USD revolving credit facility borrowings [Member] USD revolving credit facility borrowings [Member] USD revolving credit facility borrowings Loan to related party Payments for Advance to Affiliate Payments for Advance to Affiliate Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Other Nonoperating Income (Expense) [Abstract] Other Nonoperating Income (Expense) [Abstract] Dividends paid Payments of Ordinary Dividends 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] Deferred Revenue Deferred Revenue Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage Local Phone Number Local Phone Number Education [Member] Education [Member] Education [Member] Early Retirment Program Expense [Domain] Early Retirment Program Expense [Domain] Early Retirment Program Expense [Domain] Total Debt Debt, Long-Term and Short-Term, Combined Amount Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Operating Expenses Operating Expenses Graham Holdings Company Common Stockholders: Income Per Share From Continuing Operations To Common Stockholders [Abstract] Income Per Share From Continuing Operations To Common Shareholders. 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] Television Broadcasting [Member] Television Broadcasting [Member] Television Broadcasting [Member] Change in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Loss Contingency Borrower Defense Claims Discharge Loan Amount Loss Contingency Borrower Defense Claims Discharge Loan Amount The amount of money applications seek to discharge of loans. PEO Total Compensation Amount PEO Total Compensation 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] Total Cost Equity Securities, FV-NI, Cost 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 Income Statement Location [Axis] Statement of Income Location, Balance [Axis] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Unusual or Infrequent Item, or Both [Axis] Unusual or Infrequent Item, or Both [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Markel Corporation [Member] Markel Group Inc. [Member] Markel Group Inc. Debt Disclosure [Abstract] Debt Disclosure [Abstract] Common Stock [Member] Common Stock [Member] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Provider Relief Fund [Member] Provider Relief Fund [Member] Provider Relief Fund under the CARES Act Accrued Compensation and Related Benefits Deferred Compensation Liability, Classified, Noncurrent Segment Reporting [Abstract] Segment Reporting [Abstract] Entity Central Index Key Entity Central Index Key Schedule of Inventories and Contracts in Progress Schedule of Inventory, Current [Table 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. Foreign Currency Translation Adjustment [Member] Cumulative Foreign Currency Translation Adjustment [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Accretion of value included in net income Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Gain (Loss), Accretion Included in Earnings Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Gain (Loss), Accretion Included in Earnings Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Business Segments Segment Reporting Disclosure [Text Block] Current portion of long-term debt Less: current portion Long-Term Debt, Current Maturities Net Actuarial Gain [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Foreign currency exchange rate changes Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Foreign Currency Translation Gain (Loss) Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Foreign Currency Translation Gain (Loss) Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Contingent consideration accretion expense Accretion Expense Amortization of unearned stock compensation and stock option expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Restricted Stock [Member] Restricted Stock [Member] Noncontrolling interest Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value Class B Common Stock [Member] Common Class B [Member] Common Class B [Member] Title Trading Arrangement, Individual Title GHC One and GHC Two [Member] GHC One and GHC Two [Member] GHC One and GHC Two 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. Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest City Area Code City Area Code Current Liabilities Liabilities, Current [Abstract] Maximum Term of Contract Maximum Term of Contract Maximum Term of Contract Business Combination, Contingent Consideration, Liability Contingent consideration liabilities Business Combination, Contingent Consideration, Liability Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Gain on disposition of a business, property, plant and equipment and investments, net Gain (Loss) on Disposition of Assets Graham Media Group and Corporate [Member] Graham Media Group and Corporate [Member] Graham Media Group and Corporate Common shares repurchased Payments for Repurchase of Common Stock Long-Term Debt Total Long-Term Debt Long-Term Debt, Excluding Current Maturities CSI Pharmacy Holding Company, LLC CSI Pharmacy Holding Company, LLC [Member] CSI Pharmacy Holding Company, LLC [Member] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Purchase of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Equity effect of redemption of redeemable noncontrolling interest Subsequent Event Type [Axis] Subsequent Event Type [Axis] Per Share Information Attributable to Graham Holdings Company Common Stockholders Earnings Per Share [Abstract] Number of Schools ED Discharge Loans Number of Schools ED Discharge Loans The number of schools which ED will discharge loans for students. Raw materials Inventory, Raw Materials, Net of Reserves Retained earnings Retained Earnings (Accumulated Deficit) 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] 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] Class of Stock [Domain] Class of Stock [Domain] 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 Inventories Increase (Decrease) in Inventories Components of Debt Schedule of Debt [Table Text Block] Net unrealized gains in earnings from marketable equity securities still held at the end of the period Equity Securities, FV-NI, Unrealized Gain (Loss) Inventories and contracts in progress Inventories and contracts in progress Inventory, Net of Allowances, Customer Advances and Progress Billings Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Number of marketable equity securities greater than 5% of total assets Number of marketable equity securities greater than 5% of total assets Number of marketable equity securities greater than 5% of total assets Equity Awards Adjustments Equity Awards Adjustments [Member] 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 Total lease liabilities Operating Lease, Liability Underlying Securities Award Underlying Securities Amount Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Percentage of Additional Ownership Available to be Acquired Percentage of Additional Ownership Available to be Acquired The percentage of additional ownership available to be acquired by the minority shareholder. Deferred revenue Deferred Revenue, Current Add: Dividends paid-common stock outstanding Dividends, Common Stock, Cash Amendment Flag Amendment Flag Cumulative foreign currency translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Other Non-Operating Income Other Income and Other Expense Disclosure [Text Block] Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Unamortized debt issuance costs Debt Issuance Costs, Net Debt Debt Disclosure [Text Block] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Five-Year Credit Agreement maturing in 2027 [Member] Five-Year Credit Agreement maturing in 2027 [Member] Five-Year Credit Agreement maturing in 2027 Settlements or distributions Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Entity Address, Postal Zip Code Entity Address, Postal Zip Code Interest Rate Swaps maturing in 2031 and 2032 [Member] Interest Rate Swap [Member] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Potential claims Per ED Loss Contingency Potential Borrower Defense Claims Per ED Number The number of potential borrower defense claims per the Department of Education (ED). Recipient of Consideration [Domain] Recipient of Consideration [Domain] Recipient of Consideration Schedule of Investments [Table] Schedule of Investments [Table] Retirement Benefits, Description [Abstract] Retirement Benefits, Description [Abstract] Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Impairment of Intangible Assets, Indefinite-Lived (Excluding Goodwill) Other Payments for (Proceeds from) Other Investing Activities 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] GHC One [Member] GHC One [Member] GHC One [Member] Reclassification from AOCI, Current Period, Tax Provision for Income Tax Reclassification from AOCI, Current Period, Tax 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. 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] Graham Healthcare Group [Member] Healthcare [Member] Graham Healthcare Group [Member] Graham Healthcare Group [Member] Leaf Group [Member] Leaf Group [Member] Leaf Group [Member] U.S. stock index fund [Member] Equity Funds, US [Member] An investment that pools funds from many investors to invest in a combination of underlying investments, primarily equity investments, domiciled in United States of America (US). Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Numerator for basic (loss) earnings per share Net Income (Loss) Available to Common Stockholders, Basic 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. Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Investment Managers [Axis] Investment Managers [Axis] Investment Managers [Axis] 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] Total Assets Assets Education Programs [Axis] Education Programs [Axis] Education Programs Vehicle floor plan payable Floor plan payables Vehicle Floor Plan Facility Payable The amount borrowed to finance the purchase of specific vehicle inventories. Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Income taxes receivable Income Taxes Receivable, Current Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Other Liabilities Other Liabilities, Noncurrent Databases and Technology [Member] Database Rights [Member] Cost of services and goods Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Commitments and Contingencies (Note 14) Commitments and Contingencies Automotive [Member] Automotive [Member] Automotive [Member] Termination Date Trading Arrangement Termination Date Advances to Affiliate Advances to Affiliate Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Schedule of assets acquired and liabilities assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Net (Loss) Income Attributable to Graham Holdings Company Common Stockholders Net (loss) income attributable to Graham Holdings Company common stockholders Net Income (Loss) Attributable to Parent Trading Arrangement: Trading Arrangement [Axis] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Debt [Table] Debt [Table] Schedule of all debt, including both short term and long term. Credit facility current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Schedule of Allocation of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Entity File Number Entity File Number Noncontrolling Interest [Member] Noncontrolling Interest [Member] Income Statement [Abstract] Income Statement [Abstract] Entity Address, Address Line One Entity Address, Address Line One Other Temporary Equity, Other Changes Effect Of Currency Exchange Rate Change Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations Dividends on common stock Dividends, Common Stock Name Forgone Recovery, Individual Name Transaction [Domain] Transaction [Domain] Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Deferred revenue Deferred revenue Increase (Decrease) in Deferred Revenue Securities Subject to Mandatory Redemption [Member] Securities Subject to Mandatory Redemption [Member] Foreign currency translation adjustments: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent [Abstract] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Management Fee Management Fee Management fee payable by the Company in connection with management services provided under the management services agreement Investments in Marketable Equity Securities Marketable Securities [Table Text Block] Adjustment to Compensation: Adjustment to Compensation [Axis] Net Income Attributable to Noncontrolling Interests Net Income (Loss) Attributable to Noncontrolling Interest Deferred Revenue Recognized of Refundable Prepaid Amounts Deferred Revenue Recognized of Refundable Prepaid Amounts Deferred Revenue Recognized of Refundable Prepaid Amounts Document Quarterly Report Document Quarterly Report Dispositions Goodwill, Written off Related to Sale of Business Unit Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Related Party, Type [Axis] Related and Nonrelated Parties [Axis] Basic average number of common shares outstanding (in shares) Weighted average shares outstanding (shares) Weighted Average Number of Shares Outstanding, Basic Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Net Periodic Cost (Benefit) 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. Indefinite-lived intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets Total Equity As of As of Equity, Including Portion Attributable to Noncontrolling Interest Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Defined benefit plan, target allocation percentage of assets Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Other gain, net Other Nonoperating Gains (Losses) Name Awards Close in Time to MNPI Disclosures, Individual Name Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] Number of Stores Number of Stores Number of businesses acquired Number of Businesses Acquired Entity Filer Category Entity Filer Category Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Acquisition of redeemable noncontrolling interest Acquisition of Redeemable Noncontrolling Interest The fair value of the creation of a redeemable noncontrolling interest due to the acquisition of less than 100% of an entity. Acquisitions Goodwill, Acquired During Period Statistical Measurement [Domain] Statistical Measurement [Domain] Capital Expenditures Segment, Expenditure, Addition to Long-Lived Assets Contract with Customer, Asset, after Allowance for Credit Loss, Current Contract with Customer, Asset, after Allowance for Credit Loss, Current Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets Amortization Of Intangible Assets And Impairment of Goodwill and Other Long-Lived Assets Amortization Of Intangible Assets And Impairment of Goodwill and Other Long-Lived Assets 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 Segment Reporting Information [Line Items] Business Segments [Line Items] Segment Reporting Information [Line Items] All Trading Arrangements All Trading Arrangements [Member] 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). Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Summary of (Loss) Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] 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. Measurement period adjustments Goodwill, Measurement Period Adjustment Class A Common Stock [Member] Common Class A [Member] Common Class A [Member] Pay vs Performance Disclosure [Line Items] Redeemable Noncontrolling Interests As of As of Redeemable Noncontrolling Interest, Equity, Carrying Amount Accretion expense and change in fair value of contingent consideration liabilities Accretion Expense and Change in Fair Value 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. Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Mandatorily redeemable noncontrolling interest [Member] Mandatorily redeemable noncontrolling interest [Member] Mandatorily redeemable noncontrolling interest Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Lease liabilities Increase (Decrease) in Operating Lease Liability Supplemental Executive Retirement Plan (SERP) [Member] Supplemental Employee Retirement Plan [Member] Interest rate swaps Interest Rate Cash Flow Hedge Liability at Fair Value Interest Rate Swap maturing in 2028 - $75.2 million [Member] Interest Rate Swap maturing in 2028 - $75.2 million [Member] Forward based contracts in which two parties agree to swap periodic payments that are fixed at the outset of the swap contract with variable payments based on a market interest rate (index rate) over a specified period. Other assets and other liabilities, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Other Performance Measure, Amount Other Performance Measure, Amount Estimated amortization of intangible assets, 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Three Goodwill [Line Items] Goodwill [Line Items] Income taxes receivable/payable Increase (Decrease) in Income Taxes Lease Liabilities Operating Lease, Liability, Noncurrent Purchase of redeemable noncontrolling interest Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Auto dealerships [Member] Auto dealerships [Member] Auto dealerships Service cost Pension Service Cost Defined Benefit Plan, Service Cost Entity Tax Identification Number Entity Tax Identification Number Operating Income before Amortization of Intangible Assets and Impairment of Long-Lived Assets Operating Income before Amortization of Intangible Assets and Impairment of Long-Lived Assets Operating Income before Amortization of Intangible Assets and Impairment of Long-Lived Assets Schedule of Finite-Lived Intangible Assets [Table] Intangible Asset, Finite-Lived [Table] 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 Retirement Plan Type [Axis] Retirement Plan Type [Axis] AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] Guaranteed Return Guaranteed Return Preferred annual return on portfolio investments guaranteed to the Company Redeemable noncontrolling interest capital contribution Redeemable Noncontrolling Interest, Increase from Subsidiary Equity Issuance Amount of increase in redeemable noncontrolling interest from subsidiary issuance of equity interests to redeemable noncontrolling interest holders. Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Treasury Stock Treasury Stock, Common [Member] US Treasury Securities [Member] US Treasury Securities [Member] Revenue, Remaining Performance Obligation, Optional Exemption, Remaining Duration Revenue, Remaining Performance Obligation, Optional Exemption, Remaining Duration Intersegment Elimination [Member] Intersegment Eliminations [Member] Equity Components [Axis] Equity Components [Axis] Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets Operating Income (Loss) before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. Operating Income (Loss) before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets. Average borrowings outstanding Average Outstanding Debt Amount Average borrowings outstanding during the period, both short and long term. Other current assets Other Assets, Current Pro forma net income Business Acquisition, Pro Forma Net Income (Loss) Mandatorily Redeemable Noncontrolling Interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Noncurrent Redeemable noncontrolling interest capital contribution Equity effect of redeemable noncontrolling interest capital contribution Equity effect of redeemable noncontrolling interest capital contribution Total Operating Costs and Expenses Operating and Management Services Expenses Costs and Expenses Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Separation Incentive Program [Member] Separation Incentive Program [Member] Separation Incentive Program [Member] Number of television broadcast stations Number Of Television Broadcast Stations Owned Number of television broadcast stations owned by the Company. Geographical [Axis] Geographical [Axis] Gain on sale of businesses Gain (Loss) on Disposition of Business Cash flow hedges gain Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax 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] Mandatorily redeemable noncontrolling interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Fair Value of Shares York Joint Venture [Member] York Joint Venture [Member] York Joint Venture [Member] Other noncurrent assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Schedule of Non-Operating Income (Expense) [Line Items] Schedule of Non-Operating Income (Expense) [Line Items] [Line Items] for Schedule of Non-Operating Income (Expense) [Table] 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. Beginning Cash and Cash Equivalents and Restricted Cash Ending Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Marketable equity securities Total Fair Value Equity Securities, FV-NI, Current Current Assets Assets, Current [Abstract] Consolidation Items [Axis] Consolidation Items [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-Lived Intangible Assets, Major Class Name [Domain] Cash Paid for CSI Minority Shares Cash Paid for CSI Minority Shares [Member] Cash Paid for CSI Minority Shares Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Prime Rate [Member] Prime Rate [Member] Product and Service [Domain] Product and Service [Domain] Goodwill [Roll Forward] Goodwill [Roll Forward] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Cumulative realized gain on marketable securities sold or donated Cumulative realized gain (loss) on marketable securities sold or donated Amount of cumulative realized gain (loss) from sale or donation of investment in equity security Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition Amount Borrowed to Finance Business Acquisition 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 Acqusitions and Dispositions [Abstract] Acqusitions and Dispositions [Abstract] Acqusitions and Dispositions [Abstract] 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] Security Exchange Name Security Exchange Name Applicable interest rate margin Debt Instrument, Basis Spread on Variable Rate Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] 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 Weiss Weiss [Member] Weiss Proceeds from bank overdrafts Proceeds from (Repayments of) Bank Overdrafts Foreign exchange swap Foreign Currency Contracts, Liability, Fair Value Disclosure Capital Contributor [Axis] Capital Contributor [Axis] Capital Contributor [Axis] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Subsegments [Axis] Subsegments [Axis] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Amortization of net actuarial gain included in net income Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Entity [Domain] Entity [Domain] Medicare Accelerated Advanced Payment Program Relief Fund [Member] Medicare Accelerated Advanced Payment Program Relief Fund [Member] Medicare Accelerated Advanced Payment Program Relief Fund under the CARES Act Minimum percentage of total assets considered as significant concentrations Minimum percentage of plan assets considered as significant concentrations in pension plans Concentration Risk, Percentage Amount of Revenue Recognized From Provider Relief Fund Amount of Revenue Recognized From Provider Relief Fund Amount of revenue recognized from provider relief fund Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Accounts Receivable Accounts Receivable, after Allowance for Credit Loss Impairment of goodwill and other intangible assets Goodwill and Intangible Asset Impairment Investments in certain businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Estimated amortization of intangible assets, remainder of 2024 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Net income attributable to redeemable noncontrolling interests Temporary Equity, Net Income Accounts Payable and Accrued Liabilities, Current [Abstract] Accounts Payable and Accrued Liabilities, Current [Abstract] Related Party [Member] Related Party [Member] Recognized actuarial loss (gain) Defined Benefit Plan, Amortization of Gain (Loss) Interest expense Interest expense Interest Expense, Nonoperating Acquisition of redeemable noncontrolling interest Equity Effect of Acquisition of Redeemable Noncontrolling Interest Equity effect of acquisition of redeemable noncontrolling interest Provision for deferred income taxes Deferred Income Tax Expense (Benefit) Deferred payments of acquisition Payment for Contingent Consideration Liability, Financing Activities Acquisition Pro Forma Financial Information Business Acquisition, Pro Forma Information [Table Text Block] Fair Value, Recurring [Member] Fair Value, Recurring [Member] Receivable from contracts with customers, less estimated credit losses Accounts Receivable, after Allowance for Credit Loss, Current Percentage Ownership After Change in Noncontrolling Interest Ownership percentage by parent Subsidiary, Ownership Percentage, Parent Ford auto dealership Ford auto dealership [Member] Ford auto dealership [Member] Impairment of goodwill and other long-lived assets Goodwill and intangible asset impairment charge Asset Impairment Charges Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain] Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain] Framebridge and Code3 [Member] Framebridge and Code3 [Member] Framebridge and Code3 Acquisitions and Dispositions of Businesses Mergers, Acquisitions and Dispositions Disclosures [Text Block] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Investments in Affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Gain on sale of investment in affiliate Equity Method Investment, Realized Gain (Loss) on Disposal Accounts Receivable, Noncurrent Accounts Receivable, after Allowance for Credit Loss, Noncurrent Identifiable Assets Identifiable Assets Identifiable assets by segment are those assets used in the Company's operations in each business segment. Indefinite-Lived Intangible Assets Indefinite-Lived Intangible Assets (Excluding Goodwill) Amortization of intangible assets Amortization of Intangible Assets Amortization of Intangible Assets Non-US [Member] Non-US [Member] Liabilities Liabilities [Abstract] Credit loss expense and provision for other receivables Credit Loss Expense And Provision For Other Receivables The amounts of credit loss expense and provision for other receivables. Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Current Fiscal Year End Date Current Fiscal Year End Date PEO Name PEO Name Award Type [Domain] Award Type [Domain] Prior Period Reclassification Adjustment Prior Period Reclassification Adjustment Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss) before Reclassifications, Tax Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Transferred over Time [Member] Transferred over Time [Member] Revision of Prior Period [Axis] Revision of Prior Period [Axis] Deferred Income Taxes Deferred Income Tax Assets, Net Non-PEO NEO Non-PEO NEO [Member] Useful Life Finite-Lived Intangible Asset, Useful Life Total Financial Assets Investments, Fair Value Disclosure Diplomas Diplomas [Member] Diplomas Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Pension and Postretirement Plans Retirement Benefits [Text Block] Deferred income tax liability Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Recently Adopted and Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Pension and other postretirement plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Class of Stock [Axis] Class of Stock [Axis] Derivative, Basis Spread on Variable Rate Derivative, Basis Spread on Variable Rate Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Amortization of lease right-of-use asset Operating Lease, Right-of-Use Asset, Periodic Reduction Name Measure Name Entity Interactive Data Current Entity Interactive Data Current Series of Individually Immaterial Business Acquisitions [Member] Series of Individually Immaterial Business Acquisitions [Member] Pension and other post retirement benefits liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension and Other Post Retirement Benefits Liabilities Amount of pension and postretirement liabilities assumed at the acquisition date. Number of Operating Segments Number of Operating Segments New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] 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] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Applied Behavior Analysis clinics Applied Behavior Analysis clinics [Member] Applied Behavior Analysis clinics Stock-based compensation expense, net of forfeitures Share-Based Payment Arrangement, Noncash Expense Pension and Other Postretirement Plans [Member] Unrealized Gain on Pensions and Other Postretirement Plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Acquisition of business Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Interest rate Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Corporate Office [Member] Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Education, Code3 and Decile [Member] Education, Code3 and Decile [Member] Education, Code3 and Decile businesses. Percentage of Contributed Capital Percentage of Contributed Capital Percentage of Contributed Capital Numerator for diluted (loss) earnings per share Net Income (Loss) Available to Common Stockholders, Diluted Operating Expense [Member] Operating Expense [Member] Total Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest Services [Member] Service [Member] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Other indebtedness Other Long-Term Debt Deferred income tax asset Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Income from Operations Income (Loss) from Operations Operating Income (Loss) AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Variable Rate [Domain] Variable Rate [Domain] Number of reportable segments Number of Reportable Segments Total Liabilities and Equity Liabilities and Equity Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] International equities [Member] Defined Benefit Plan, Equity Securities, Non-US [Member] Interest income Investment Income, Interest Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Capitalized Contract Cost Capitalized Contract Cost [Table Text Block] Organization, Basis of Presentation and Recent Accounting Pronouncements Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Individual: Individual [Axis] AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Product and Service [Axis] Product and Service [Axis] Statement [Line Items] Statement [Line Items] Redeemable noncontrolling interest Business Combination Acquisition Of Less than 100 Percent Redeemable Noncontrolling Interest Fair Value This element represents the fair value of the redeemable noncontrolling interest in the acquiree at the acquisition date. 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). Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis] Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis] Acquisition purchase price Business Combination, Consideration Transferred Intersubsegment Eliminations [Member] Intersubsegment Eliminations [Member] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] 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 Schedule of Error Corrections and Prior Period Adjustments Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] Loss contingency, estimate of possible loss Loss Contingency, Estimate of Possible Loss Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Contract with Customer, Asset, Net, Noncurrent Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent Loan Receivable, Payment Terms 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. Derivative, Fixed Interest Rate Derivative, Fixed Interest Rate Minimum [Member] Minimum [Member] Adoption Date Trading Arrangement Adoption Date Other receivables Other Receivables Credit loss (recovery) expense Accounts Receivable, Credit Loss Expense (Reversal) Segments [Axis] Segments [Axis] 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] Pro forma operating revenues Business Acquisition, Pro Forma Revenue Return of investment in equity affiliates Proceeds from Equity Method Investment, Distribution, Return of Capital Exercise Price Award Exercise Price Arrangement Duration Trading Arrangement Duration Summary of Other Comprehensive Loss) Comprehensive Income (Loss) [Table Text Block] VoluntaryRetirementIncentiveProgram [Member] VoluntaryRetirementIncentiveProgram [Member] Voluntary Retirement Incentive Program Redeemable Noncontrolling Interest, Equity, Common, Redemption Value Redeemable Noncontrolling Interest, Equity, Common, Redemption Value Adjustments [Member] Revision of Prior Period, Error Correction, Adjustment [Member] Licensure and Accreditation [Member] Licensure and Accreditation [Member] Licensure And Accreditation [Member] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Total pension and other postretirement plans, before tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Alphabet and Berkshire Hathaway Common Stock [Member] Alphabet And Berkshire Hathaway Common Stock [Member] Alphabet and Berkshire Hathaway Common Stock [Member] Value of investments Investments Long-term Contract with Customer [Member] Long-Term Contract with Customer [Member] Kaplan International [Member] Kaplan International [Member] Kaplan International [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Equity Funds [Member] Equity Funds [Member] Estimated amortization of intangible assets, 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Four All Individuals All Individuals [Member] Percent of plan assets managed internally by the company Percent of Plan Assets Managed Internally by Company The percentage of plan assets managed internally by the Company. Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] Variable Rate [Axis] Variable Rate [Axis] Fair value of debt instrument Debt Instrument, Fair Value Disclosure Information related to Disposal Group Schedule Of Disposal Groups Excluding Discontinued Operations Income Statement Balance Sheet And Additional Disclosures [Table Text Block] Tabular disclosure of information related to a disposal group. Excludes a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component. Other income, net Total Other Non-Operating Income Other Income, Net Other Nonoperating Income (Expense) 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 Goodwill, beginning balance Goodwill, ending balance Goodwill, Gross Other Postretirement Benefit Plan, Defined Benefit [Member] Other Postretirement Plans [Member] Other Postretirement Benefits Plan [Member] Single Equity Concentration [Member] Single Equity Concentration [Member] Information about an entity's defined benefit plan's significant investment concentrations in either a single entity, type of industry, foreign country and/or individual fund. Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] 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). Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Other Segments Other Businesses [Member] Other Operating Segment [Member] Business Acquisition, Transaction Costs Business Acquisition, Transaction Costs Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Related Party, Type [Domain] Related and Nonrelated Parties [Domain] Accounts payable, vehicle floor plan payable and accrued liabilities Total Accounts payable and Accrued liabilities Accounts Payable and Accrued Liabilities, Current Delayed Draw Term Loan maturing in 2028 - $50 million [Member] Delayed Draw Term Loan maturing in 2028 - $50 million [Member] Delayed Draw Term Loan maturing in 2028 - $50 million Supplier Finance Program [Axis] Supplier Finance Program [Axis] Liability Class [Axis] Liability Class [Axis] Net borrowings (payments) under revolving credit facilities Proceeds from (Repayments of) Lines of Credit Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Deferred Income Taxes Deferred Income Tax Liabilities, Net Gain on marketable equity securities and cost method investments, net Unrealized Gain (Loss) on Investments Amortized intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Amortization Of Intangible Assets And Impairment of Long-Lived Assets Amortization Of Intangible Assets And Impairment of Long-Lived Assets Amortization Of Intangible Assets And Impairment of Long-Lived Assets Bachelors Bachelors [Member] Bachelors Intangible asset impairment charge Impairment of Intangible Assets, Finite-Lived 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. Contingencies Commitments and Contingencies Disclosure [Text Block] Measure: Measure [Axis] Capital Term Loan maturing in 2028 - $65 million [Member] Capital Term Loan maturing in 2028 - $65 million [Member] Capital Term Loan maturing in 2028 - $65 million Non-compete Agreements [Member] Noncompete Agreements [Member] Investments [Abstract] Investments [Abstract] Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Group of Senior Managers of GHG [Member] Unsecured notes Unsecured Debt Other Comprehensive Income (Loss) [Line Items] Other Comprehensive Income (Loss) [Line Items] [Line Items] for Other Comprehensive Income (Loss) [Table] Entity Emerging Growth Company Entity Emerging Growth Company Indefinite-lived Intangible Assets [Axis] Indefinite-Lived Intangible Assets [Axis] Graham Holdings Company [Member] Graham Holdings Company [Member] Graham Holdings Company [Member] 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 Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassifications, before tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Defined Benefit Plan Assets Total [Member] Defined Benefit Plan Assets Total [Member] -- None. No documentation exists for this element. -- Schedule of Accounts Payable, Vehicle Floor Plan Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Distribution to redeemable noncontrolling interest Equity effect, distribution to temporary equity Equity effect, distribution to temporary equity Equity Component [Domain] Equity Component [Domain] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Net amount reclassified from accumulated other comprehensive income (loss) Reclassifications, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Entity Shell Company Entity Shell Company Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Balance of costs to obtain a contract Capitalized Contract Cost, Net Cumulative undistributed income in investments in affiliates Retained Earnings, Undistributed Earnings from Equity Method Investees Statement [Table] Statement [Table] Counterparty Name [Axis] Counterparty Name [Axis] Measurement Frequency [Domain] Measurement Frequency [Domain] N2K Networks [Member] N2K Networks [Member] N2K Networks Supplemental Education [Member] Supplemental Education [Member] Supplemental Education Consolidation Items [Domain] Consolidation Items [Domain] Concentration in single marketable equity security [Member] Concentration in single marketable equity security [Member] Concentration in single marketable equity security Deferred revenue recognized Deferred Revenue, Revenue Recognized Change in capitalized contract cost, other Change in Capitalized Contract Cost, Other Change in capitalized contract cost, other Level 1 Fair Value, Inputs, Level 1 [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Total Current Assets Assets, Current Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Revision of Prior Period [Domain] Revision of Prior Period [Domain] Investment Managers [Domain] Investment Managers [Domain] [Domain] for Investment Managers [Axis] Test Preparation [Member] Test Preparation [Member] Test Preparation [Member] Revenues of acquired companies since acquisition date Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Adjustments for New Accounting Pronouncements [Axis] Accounting Standards Update [Axis] Manufacturing [Member] Manufacturing [Member] Manufacturing business Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Cost method investments Equity Securities without Readily Determinable Fair Value, Amount Other [Member] Other [Member] Other Intangible Assets [Member] Accumulated other comprehensive income, net of taxes Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Changes in fair value Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Gain (Loss), Changes in Fair Value Fair​ Value, ​Measurement​ With ​Unobservable ​Inputs ​Reconciliations, ​Recurring ​Basis, ​Liability​, Gain (Loss), Changes in Fair Value Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Net Cash Used in Financing Activities Net Cash Provided by (Used in) Financing Activities Investments in equity affiliates and cost method investments Payments To Acquire Equity Method And Cost Method Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence or cost method investments. Entity Registrant Name Entity Registrant Name Transferred at Point in Time [Member] Transferred at Point in Time [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Unusual or Infrequent Item, or Both [Domain] Unusual or Infrequent Item, or Both [Domain] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Promissory Note for CSI Minority Shares Promissory Note for CSI Minority Shares [Member] Promissory Note for CSI Minority Shares Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Fair Value as of Grant Date Award Grant Date Fair Value Prepaid Pension Cost Assets for Plan Benefits, Defined Benefit Plan Level 2 Fair Value, Inputs, Level 2 [Member] Common Stockholders’ Equity Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Costs amortized during the period Capitalized Contract Cost, Amortization Geographical [Domain] Geographical [Domain] Early Retirement Program Expense [Axis] Early Retirment Program Expense [Axis] -- None. No documentation exists for this element. -- Restatement Determination Date: Restatement Determination Date [Axis] Title of 12(b) Security Title of 12(b) Security Concentration Risk Type [Axis] Concentration Risk Type [Axis] Common stock Common Stock, Value, Issued Estimated amortization of intangible assets, after 2028 Finite-Lived Intangible Asset, Expected Amortization, after Year Four Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Stock Compensation Liabilities Assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Stock Compensation Liabilities Assumed Value of liabilities assumed at the acquistion date related to acquiree's stock compensation plan Weighted average interest rate Debt Instrument, Interest Rate During Period Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Amortized Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets [Line Items] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Preferred Stock Preferred Stock, Value, Issued Basic net (loss) income per common share (in USD per share) Basic income (loss) per common share (in usd per share) Earnings Per Share, Basic Percentage of Refundable Amounts Included Within Contract Liabilities Percentage of Refundable Amounts Included Within Contract Liabilities Percentage of Refundable Amounts Included Within Contract Liabilities. Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Ownership [Domain] Ownership [Domain] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Percentage of total plan assets Defined Benefit Plan Assets Allocation (Percent) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Schedule of Goodwill [Table] Goodwill [Table] Total Current Liabilities Liabilities, Current CARES Act relief from COVID-19 [Member] CARES Act relief from COVID-19 [Member] CARES Act relief from COVID-19 As Previously Reported [Member] Previously Reported [Member] Net proceeds from vehicle floor plan payable Proceeds From (Payments Of) Vehicle Floor Plan Payable Net The net cash inflow or cash outflow from proceeds or repayment of the vehicle floor plan payable. Estimated amortization of intangible assets, 2025 Finite-Lived Intangible Asset, Expected Amortization, Year One Line of credit facility outstanding Credit facility Long-Term Line of Credit Transaction [Axis] Transaction [Axis] Transaction [Axis] Noncontrolling interest capital contribution Noncontrolling Interest, Increase from Subsidiary Equity Issuance Private investment fund [Member] Private Equity Funds [Member] Commercial note with Truist Bank maturing in 2031 - $24.75 million [Member] Commercial note with Truist Bank maturing in 2031 - $24.75 million [Member] Commercial note with Truist Bank maturing in 2031 - $24.75 million Operating Revenues Revenues Net proceeds from disposition of a business, property, plant and equipment and investments 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. Assets, Total [Member] Assets, Total [Member] 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] Education Programs [Domain] Education Programs [Domain] Education Programs Entity Address, City or Town Entity Address, City or Town Issuance of borrowings Proceeds from Issuance of Long-Term Debt Claims received Loss Contingency Borrower Defense Claims Received Number Number of claims received Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Loss Contingencies [Table] Loss Contingencies [Table] Business Acquisition [Axis] Business Acquisition [Axis] Early retirement programs and special separation benefit expense Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits 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] Berkshire Hathaway [Member] Berkshire Hathaway [Member] Berkshire Hathaway Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Repurchase of Class B Common Stock Treasury Stock, Value, Acquired, Cost Method Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Other accrued liabilities Other Accrued Liabilities, Current Document Period End Date Document Period End Date Issuance of noncontrolling interest Proceeds from Noncontrolling Interests Finished goods Inventory, Finished Goods, Net of Reserves Impairment of cost method investments Impairment of cost method investments Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount 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). Equity in (earnings) losses of affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions 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. Insider Trading Arrangements [Line Items] Cash overdrafts Bank Overdrafts CARES Act Fund [Domain] CARES Act Fund [Domain] CARES Act Fund [Domain] Deferred revenue recognized in period related to beginning balance Contract with Customer, Liability, Revenue Recognized Foreign Investments [Member] Foreign Investments [Member] Information about the entity's defined pension plan foreign investments. Document Transition Report Document Transition Report Gain on cost method investments Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Entity Current Reporting Status Entity Current Reporting Status Gain on Marketable Equity Securities Gain (Loss) on Securities [Table Text Block] Retained Earnings [Member] Retained Earnings [Member] Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Subsidiary, Ownership Percentage, Noncontrolling Owner 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. Basis of Presentation Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Executive Category: Executive Category [Axis] Network Affiliation Agreements [Member] Contract-Based Intangible Assets [Member] Intersection Holdings [Member] Intersection [Member] Intersection Holdings,LLC [Member] Income Statement Location [Domain] Statement of Income Location, Balance [Domain] Company Selected Measure Name Company Selected Measure Name