Organization, Consolidation and Presentation of Financial Statements [Abstract] New Accounting Pronouncement, Early Adoption [Table] New Accounting Pronouncement, Early Adoption [Table] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] New Accounting Pronouncement, Early Adoption [Line Items] New Accounting Pronouncement, Early Adoption [Line Items] Schedule of Prospective Adoption of New Accounting Pronouncements Schedule of Prospective Adoption of New Accounting Pronouncements [Table Text Block] Schedule of New Accounting Pronouncements and Changes in Accounting Principles Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Student and Customer Relationships [Member] Customer Relationships [Member] Trade Names and Trademarks [Member] Trademarks and Trade Names [Member] Network Affiliation Agreements [Member] Contract-Based Intangible Assets [Member] Databases and Technology [Member] Database Rights [Member] Non-compete Agreements [Member] Noncompete Agreements [Member] Other [Member] Other Intangible Assets [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Amortized Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Useful Life Finite-Lived Intangible Asset, Useful Life Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Carrying Amount Finite-Lived Intangible Assets, Net Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] FCC licenses [Member] Operating and Broadcast Rights [Member] Licensure and Accreditation [Member] Licensure and Accreditation [Member] Licensure And Accreditation [Member] Indefinite-Lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets Indefinite-lived Intangible Assets (Excluding Goodwill) Prospective Adoption of New Accounting Pronouncements [Table] Prospective Adoption of New Accounting Pronouncements [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 [Member] Accounting Standards Update 2014-09 [Member] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Item Effected [Line Items] Item Effected [Line Items] Accounts receivable, net Accounts and Other Receivables, Net, Current Inventories and contracts in progress Inventory, Net of Allowances, Customer Advances and Progress Billings Other current assets Other Assets, Current Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Deferred revenue Deferred Revenue, Current Deferred income taxes Deferred Income Tax Liabilities, Net Retained earnings Retained Earnings (Accumulated Deficit) Fair Value Disclosures [Abstract] 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] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Other Businesses [Member] Other Segments [Member] Other Businesses [Member] Other Businesses [Member] Other Businesses [Member] Healthcare [Member] Graham Healthcare Group [Member] Graham Healthcare Group [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Forney [Member] Forney [Member] Forney [Member] Goodwill and Intangible Asset Impairment Goodwill and Intangible Asset Impairment Intangible asset impairment charge Impairment of Intangible Assets, Finite-lived Goodwill and other long-lived asset impairment charge Asset Impairment Charges Amortization of Intangible Assets Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Amortization of intangible assets Amortization of Intangible Assets Estimated amortization of intangible assets, remainder of 2018 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year Estimated amortization of intangible assets, 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Two Estimated amortization of intangible assets, 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Three Estimated amortization of intangible assets, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Four Estimated amortization of intangible assets, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Five Estimated amortization of intangible assets, after 2022 Finite-Lived Intangible Assets, Amortization Expense, after Year Five Retirement Benefits, Description [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Defined Benefit Pension Plan [Member] Pension Plan [Member] Supplemental Executive Retirement Plan (SERP) [Member] Supplemental Employee Retirement Plan [Member] Other Postretirement Plans [Member] Other Postretirement Benefits Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of prior service cost (credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Recognized actuarial loss (gain) Defined Benefit Plan, Amortization of Gain (Loss) Net Periodic 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. Curtailment gain Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Special separation benefit expense Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits Net Periodic Cost (Benefit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments [Member] Operating Segments [Member] Corporate Office [Member] Corporate, Non-Segment [Member] Intersegment Elimination [Member] Intersegment Eliminations [Member] Education [Member] Education [Member] Education [Member] Television Broadcasting [Member] Television Broadcasting [Member] Television Broadcasting [Member] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] Kaplan Corporate and Other [Member] Kaplan Corporate and Other [Member] Kaplan Corporate And Other [Member] Reportable Subsegments [Member] Reportable Subsegments [Member] Intersubsegment Eliminations [Member] Intersubsegment Eliminations [Member] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Kaplan International [Member] Kaplan International [Member] Kaplan International [Member] Higher Education [Member] Higher Education [Member] Higher Education [Member] Test Preparation [Member] Test Preparation [Member] Test Preparation [Member] Professional (U.S.) [Member] Professional (U.S.) [Member] Professional (U.S.) [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Operating Revenues Revenues Income (Loss) from Operations Operating Income (Loss) Equity in earnings (losses) of affiliates, net Income (Loss) from Equity Method Investments Interest Expense, Net Interest Income (Expense), Net Debt Extinguishment Costs Gain (Loss) on Extinguishment of Debt Non-operating pension and postretirement benefit income, net Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component Gain on marketable equity securities, net Equity Securities, FV-NI, Gain (Loss) Other income, net Other Nonoperating Income (Expense) Income Before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Depreciation of property, plant and equipment Depreciation Amortization of Intangible Assets Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long-Lived Assets Amortization of intangible assets and impairment of goodwill and other long-lived assets during the period. Pension Expense Identifiable Assets Identifiable Assets Identifiable assets by segment are those assets used in the Company's operations in each business segment. Marketable equity securities Equity Securities, FV-NI Marketable Equity Securities Available-for-sale Securities, Equity Securities Investments in Affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Prepaid Pension Cost Assets for Plan Benefits, Defined Benefit Plan Total Assets Assets Other Postretirement Benefit Plan, Defined Benefit [Member] Statement [Line Items] Statement [Line Items] Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Schedule of Allocation of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Axis] Income Tax Authority, Name [Domain] Income Tax Authority, Name [Domain] Her Majesty's Revenue and Customs (HMRC) [Member] Her Majesty's Revenue and Customs (HMRC) [Member] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Diaz Case [Member] Diaz Case [Member] United States of America ex rel. Carlos Urquilla-Diaz et al. v. Kaplan University et al., included three separate complaints: Diaz, Wilcox and Gillespie. Diaz Claims [Member] Diaz Claims [Member] Diaz claims included in the United States of America ex rel. Carlos Urquilla-Diaz et al. v. Kaplan University et al. complaint. [Member] Urquilla-Diaz And Jajdelski Case [Member] Urquilla-Diaz And Jajdelski Cases [Member] United States of America ex rel. Carlos Urquilla-Diaz et al. v. Kaplan University et al. (unsealed March 25, 2008) and United States of America ex rel. Charles Jajdelski v. Kaplan Higher Education Corp. et al. (unsealed January 6, 2009). [Member] UK Pathways [Member] UK Pathways [Member] UK Pathways [Member] Kaplan University [Member] Kaplan University [Member] -- None. No documentation exists for this element. -- Transaction [Axis] Transaction [Axis] Transaction [Axis] Transaction Type [Domain] Transaction Type [Domain] Transaction Type [Domain] Sale of KHE Campuses business [Member] Sale Of KHE Campuses Business [Member] Sale of KHE Campuses business [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of existing legal claims or proceedings that are likely to have a material effect on the Company's business Loss Contingency, Pending Claims, Number Loss contingency, estimate of possible loss Loss Contingency, Estimate of Possible Loss Deferred Charges and Other Assets Other Assets, Noncurrent Secondarily Liable Leases Secondarily Liable Leases Amount of lease obligations for which the Company is secondarily liable. Number of unsealed cases filed by former employees under the U.S. Federal False Claims Act Number Of Unsealed Cases Filed By Former Employees Under U S Federal False Claims Act Number of unsealed cases filed by former employees under the U.S. Federal False Claims Act Separate complaints included In Diaz Case received rulings Separate Complaints Included In A Series Of Rulings On Number of separate complaints included in the Diaz case that the U.S. District Court for the Southern District of Florida issued a series of rulings on. Remaining employment claim in the Diaz complaint Remaining Employment Claim In The Diaz Complaint Number of remaining employment claim in the Diaz complaint with the U.S. District Court for the Southern District of Florida. Number of allegations not dismissed Number Of Dismissed Allegations Reversed By The US Circuit Court For The Ninth Judicial Circuit Number of dismissed allegations reversed by the U.S. Circuit Court for the Ninth Judicial Circuit. Number of pending program reviews Number of pending program reviews Number of pending program reviews. Number of claims affirmed for dismissal by US Court of Appeal Number Of Claims Affirmed For Dismissal by US Court of Appeals Number of claims affirmed for dismissal by the U.S. Court of Appeals for the Eleventh Judicial Court. Number of claims appealed Number of Claims Appealed Number of claims appealed to and heard by the U.S. Court of Appeals for the Eleventh Judicial Court. Number Of Preliminary Program Review Reports received Number Of Preliminary Program Review Reports Received The number of Preliminary Program Review Reports received. Length of program review Length Of Full Review Of Student Files The length of a full review of student files. Length of accreditation term reaffirmed Accreditation Term Reaffirmed The length of the accreditation reaffirmed by the HLC. Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer Revenue from Contract with Customer [Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Acquisitions And Dispositions [Abstract] Acquisitions and Dispositions Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Graham Healthcare Group [Member] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Kaplan University Transaction [Member] Residential Healthcare Michigan hospital joint venture [Member] Residential And Michigan Hospital Joint Venture [Member] Residential and a Michigan hospital joint venture [Member] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Axis] Period of Transition Operations and Support Agreement [Domain] Period of Transition Operations and Support Agreement [Domain] [Domain] for Period of Transition Operations and Support Agreement [Axis] March 22, 2018 through June 30, 2022 [Member] March 22, 2018 through June 30, 2022 [Member] Period of time March 22, 2018 through June 30, 2022 for which the TOSA term applies (first 4 years) March 22, 2018 through June 30, 2023 [Member] March 22, 2018 through June 30, 2023 [Member] Period of time March 22, 2018 through June 30, 2023 for which the TOSA term applies (first 5 years) July 1, 2022 through June 30, 2027 [Member] July 1, 2022 through June 30, 2027 [Member] Period of time July 1, 2022 through June 30, 2027 for which the TOSA term applies (Years 5-9) After June 30, 2023 [Member] After June 30, 2023 [Member] Period of time after June 30, 2023 (6th year and beyond) for which the TOSA term applies After June 30, 2024 [Member] After June 30, 2024 [Member] Period of time after June 30, 2024 (7th year and beyond) for which the TOSA term applies After June 30, 2027 [Member] After June 30, 2027 [Member] Period of time after June 30, 2027 for which the TOSA term applies After June 30, 2048 [Member] After June 30, 2048 [Member] Period of time after June 30, 2048 (thirtieth year) for which the TOSA term applies Recipient of Consideration [Axis] Recipient of Consideration [Axis] Recipient of Consideration Recipient of Consideration [Domain] Recipient of Consideration [Domain] [Domain] for Recipient of Consideration Purdue University Global [Member] Purdue University Global [Member] Purdue University Global Kaplan [Member] Kaplan [Member] Kaplan [Member] KHE Campuses [Member] KHE Campuses [Member] KHE Campuses [Member] Kaplan China [Member] Kaplan China [Member] Kaplan China [Member] Celtic Healthcare Inc [Member] Celtic Healthcare Inc [Member] -- None. No documentation exists for this element. -- Residential Healthcare [Member] Residential Healthcare Group Inc [Member] Residential Healthcare Group Inc [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Celtic Healthcare Allegheny Health Network Joint Venture [Member] CelticHealthcareAlleghenyHealthNetworkJointVenture [Member] A joint venture formed between Celtic Healthcare and Allegheny Health Network 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] Percentage of Cost Efficiencies Percentage of Cost Efficiencies Percentage of Cost Efficiencies to be used to Calculate Additional Efficiency Payment First Five Years of Transition and Operations Support Agreement First Five Years of Transition and Operations Support Agreement First five years of TOSA Amount of Priority Payment Per Year Beyond Costs Amount of Priority Payment Per Year Beyond Costs Amount of priority payment made to Purdue University Global beyond costs before any payment to Kaplan Advance Related To Kaplan University Transaction Advance Related To Kaplan University Transaction Advance related to Kaplan University Transaction. Payments to Fund Long-term Loans to Related Parties Payments to Fund Long-term Loans to Related Parties Kaplan Share of Purdue University Global Revenue Kaplan Share of Purdue University Global Revenue Percentage representing Kaplan's fee based on Purdue University Global Revenue Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Initial Term Transition and Operations Support Agreement Renewal Periods Transition and Operations Support Agreement Renewal Periods Transition and Operations Support Agreement Renewal Periods after initial 30 year term Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Buy-Out Option Eligible Year Transition and Operations Support Agreement Buy-Out Option Eligible Year Percentage of Revenue After Kaplan Efficiency Payment Percentage of Revenue Remaining To Be Paid Percentage of Purdue University Global Revenue remaining after Kaplan Efficiency Payment and other adjustments paid to Purdue University Global Kaplan University Transaction Termination Fee Kaplan University Transaction Termination Fee Percent of Purdue Global University revenue for preceding 12 month period to be paid to terminate the Transition and Operations Support Agreement Purdue University Global Final Payment Note Duration Purdue University Global Final Payment Note Duration Duration of note for final payment made by Purdue University Global to Kaplan upon termination of TOSA Annual Purdue University Global Cash Operating Losses Annual Purdue University Global Cash Operating Losses Annual Purdue University Global cash operating losses threshold for option to terminate Transition and Operations Support Agreement Number of Consecutive Years of Purdue University Global Cash Operating Losses Number of Consecutive Years of Purdue University Global Cash Operating Losses Number of consecutive years of Purdue University Global cash operating losses for option to terminate Transition and Operations Support Agreement Aggregate Purdue University Global cash operating losses Aggregate Purdue University Global Cash Operating Losses Aggregate Purdue University Global cash operating losses threshold for option to terminate Transition and Operations Support Agreement Gain on the sale of businesses Gain (Loss) on Disposition of Business Gain Related to Contingent Consideration Gain Related to Contingent Consideration Contingent consideration gain related to the sale of a business. Number of businesses disposed Number Of Businesses Disposed The number of businesses disposed of by the entity during the period. Percentage of joint venture sold Percentage Of Joint Venture Sold The percentage of a joint venture sold. Ownership percentage of joint venture Equity Method Investment, Ownership Percentage Noncontrolling interest purchased Noncontrolling Interest Purchased Percent of noncontrolling interest purchased during the period. Change in redemption value of manditorily redeemable noncontrolling interest Noncontrolling Interest, Change in Redemption Value Redemption value of redeemable noncontrolling interest Redeemable Noncontrolling Interest, Equity, Common, Redemption Value Noncontrolling interest exchanged Noncontrolling Interest Exchanged The percentage of redeemable noncontrolling interest exchanged. Ownership percentage of manditorily redeemable noncontrolling interest by noncontrolling owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Ownership oercentage by parent Noncontrolling Interest, Ownership Percentage by Parent Number of nationally accredited ground campuses sold Number Of Nationally Accredited Ground Campuses Sold The number of nationally accredited ground campuses sold. Maximum letter of credit or other credit support Guarantor Obligations, Maximum Exposure, Undiscounted Term for letter of credit Length Of Guarantee Length of time for letter of credit or other credit support, if issued. Impairment of long-lived assets Impairment Of Long Lived Assets The aggregate amount of write-downs recognized during the period for long-lived assets. Unfavorable out of period expense adjustment Immaterial Error Correction Amount Amount of effect on financial statements related to corrections of prior period errors in the current period financial statements when the effect of the prior period error was immaterial to the prior period financial statements and the current period correction is immaterial to the current period financial statements. Number of nationally accredited ground campuses Number Of Nationally Accredited Ground Campuses To Be Sold The number of nationally accredited ground campuses to be sold. Gain on the formation of a joint venture Deconsolidation, Gain (Loss), Amount Other Nonoperating Income (Expense) [Abstract] Other Non-Operating Income Other Income and Other Expense Disclosure [Text Block] Contract with Customer, Liability [Abstract] Deferred Revenue Deferred Revenue Deferred Revenue, Period Decrease Percentage Deferred Revenue, Period Increase (Decrease) Percentage Deferred Revenue, Period Increase (Decrease) Percentage Accounts and Notes Receivable, Net [Abstract] Accounts Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Retained Earnings [Member] Retained Earnings [Member] Accounting Standards Update 2016-01 [Member] Accounting Standards Update 2016-01 [Member] Adjustment [Member] Adjustments for New Accounting Pronouncement [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Revenues Income from Operations Costs and Expenses Costs and Expenses Cumulative Effect of New Accounting Principle in Period of Adoption Cumulative Effect of New Accounting Principle in Period of Adoption Income Tax Disclosure [Abstract] Income Taxes [Table] Income Taxes [Table] -- None. No documentation exists for this element. -- Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State and Local Jurisdiction [Member] State and Local Jurisdiction [Member] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Bad debt expense Provision for Doubtful Accounts Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Pro Forma Operating Revenues Business Acquisition, Pro Forma Revenue Pro Forma Net Income Business Acquisition, Pro Forma Net Income (Loss) Schedule of Goodwill [Table] Schedule of Goodwill [Table] Professional (U.S.) [Member] Kaplan Professional [Member] Kaplan Professional [Member] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Goodwill, beginning balance Goodwill, Gross Accumulated impairment losses, beginning balance Goodwill, Impaired, Accumulated Impairment Loss Goodwill, net, beginning balance Goodwill Reallocation Goodwill, Transfers Acquisitions Goodwill, Acquired During Period Impairment Goodwill, Impairment Loss Dispositions Goodwill, Written off Related to Sale of Business Unit Foreign currency exchange rate changes Goodwill, Foreign Currency Translation Gain (Loss) Goodwill, ending balance Accumulated impairment losses, ending balance Goodwill, net, ending balance Pension and Postretirement Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Investments [Abstract] Total Cost Equity Securities, FV-NI, Cost Total cost Available-for-sale Equity Securities, Amortized Cost Basis Gross unrealized gains Equity Securities FV-NI, Accumulated Gross Unrealized Gain Amount of unrealized gain on investment on equity security measured at fair value with change in fair value recognized in net income (FV-NI). Gross unrealized gains Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax Total Fair Value Total Fair Value Investments Investment [Text Block] Earnings Per Share [Abstract] Summary of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Antidilutive Weighted Average Restricted Stock and Options Antidilutive Weighted Average Restricted Stock [Table Text Block] [Table Text Block] for Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of restricted stock using the treasury stock method. Debt Disclosure [Abstract] Components of Debt Schedule of Debt [Table Text Block] Number of reportable segments Number of Reportable Segments Acqusitions and Dispositions [Abstract] Acqusitions and Dispositions [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] College for Financial Planning [Member] College for Financial Planning [Member] College for Financial Planning Professional Publications, Inc. [Member] Professional Publications, Inc. [Member] Professional Publications, Inc. Genesis [Member] Genesis [Member] Genesis [Member] Red Marker [Member] Red Marker [Member] Red Marker [Member] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Hoover Treated Wood Products [Member] Hometown Home Health and Hospice [Member] Hometown Home Health and Hospice [Member] Hometown Home Health and Hospice Furnlite Inc [Member] Furnlite Inc [Member] Furnlite Inc [Member] Marketplace Strategy [Member] Marketplace Strategy [Member] Marketplace Strategy [Member] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] Mander Portman Woodward [Member] Mander Portman Woodward [Member] Mander Portman Woodward [Member] Osborne Books [Member] Osborne Books [Member] Osborne Books [Member] Electri-Cable Assemblies [Member] Electri-Cable Assemblies [Member] Electri-Cable Assemblies [Member] Residential Healthcare Group Inc [Member] SocialCode [Member] SocialCode [Member] SocialCode [Member] Dekko [Member] Group Dekko [Member] Group Dekko [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential Hospice Illinois [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Residential Home Health Illinois [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Percentage of interest acquired Business Acquisition, Percentage of Voting Interests Acquired Number of businesses acquired Number of Businesses Acquired Acqusition purchase price Business Combination, Consideration Transferred 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. Purchase Price Net of Cash Payments to Acquire Businesses, Net of Cash Acquired 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. Business Acquisition, Transaction Costs Business Acquisition, Transaction Costs Goodwill expected to be deductible for income tax purposes Business Acquisition, Goodwill, Expected Tax Deductible Amount Revenues of acquired companies since acquisition date Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Operating loss of acquired companies since acquisition date Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Adjustment to goodwill Goodwill, Purchase Accounting Adjustments Statement [Table] Statement [Table] Prior Period Adjustments [Axis] Prior Period Adjustments [Axis] -- None. No documentation exists for this element. -- Prior Period Adjustments [Domain] Prior Period Adjustments [Domain] -- None. No documentation exists for this element. -- Q3 2015 [Member] Q3 2015 [Member] Q3 2015 [Member] Number of television broadcast stations Number Of Television Broadcast Stations Owned Number of television broadcast stations owned by the Company. Number of Operating Segments Number of Operating Segments Percentage of ownership indicating control for consolidation purposes Percentage Of Ownership Indicating Control For Consolidation Purposes Defines percentage of ownership required in the Company's domestic and foreign subsidiaries for consolidation of assets, liabilities, results of operations and cash flows of the Company. Debt [Table] Debt [Table] Schedule of all debt, including both short term and long term. Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] 5.75% Unsecured Notes due June 1, 2026 [Member] Five Point Seven Five Percent Unsecured Notes due June 1, 2026 [Member] Five Point Seven Five Percent Unsecured Notes due June 1, 2026 [Member] 7.25% Unsecured Notes due February 1, 2019 [Member] Seven Point Two Five Percent Unsecured Notes Due February One Two Thousand And Nineteen [Member] Seven Point Two Five Percent Unsecured Notes due February One, Two Thousand and Nineteen [Member] Kaplan Four-Year Credit Agreement dated July 14, 2016 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Kaplan Four Year Credit Agreement Dated July 14, 2016 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Five-Year Credit Agreement dated May 30, 2018 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Unsecured notes Unsecured Debt UK Credit Facility Long-term Line of Credit Other indebtedness Other Long-term Debt Total Debt Debt, Long-term and Short-term, Combined Amount Less: current portion Debt, Current Total Long-Term Debt Long-term Debt, Excluding Current Maturities Unamortized debt issuance costs Debt Issuance Costs, Net Business Segments [Table] Business Segments [Table] Business Segments [Table] Business Segments [Line Items] Geographical [Axis] Geographical [Axis] Plan Asset Location [Domain] Geographical [Domain] U.S. [Member] UNITED STATES International [Member] Non-US [Member] Defined Benefit Pension Plans [Member] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Equity Securities [Member] Equity Securities [Member] Equity Funds [Member] Equity Funds [Member] Fixed income securities [Member] Fixed Income Securities [Member] Defined Benefit Plan Assets Allocation (Percent) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Income Statement [Abstract] Operating Costs and Expenses [Abstract] Operating Operating Expense Generally recurring costs associated with normal operations including the portion of these expenses which can be clearly related to production and included in cost of sales or services. Excludes selling, general and administrative expenses. Selling, general and administrative Selling, General and Administrative Expenses The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. Also includes expenses such as bad debt expense, and gain (loss) on disposition of assets. Impairment of goodwill and other long-lived assets Total Operating Costs and Expenses Income from Operations Equity in earnings (losses) of affiliates, net Interest income Investment Income, Interest Interest expense Interest Expense Debt extinguishment costs Other income, net Income Before Income Taxes Provision for Income Taxes Income Tax Expense (Benefit) Net Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net Income Attributable to Noncontrolling Interests Net Income (Loss) Attributable to Noncontrolling Interest Net Income Attributable to Graham Holdings Company Common Stockholders Net Income (Loss) Attributable to Parent Per Share Information Attributable to Graham Holdings Company Common Stockholders Basic net income per common share in dollars per share Earnings Per Share, Basic Basic average number of common shares outstanding in shares Weighted Average Number of Shares Outstanding, Basic Diluted net income per common share in dollars per share Earnings Per Share, Diluted Diluted average number of common shares outstanding in shares Weighted Average Number Of Potentially Dilutive Shares Outstanding The weighted average number of shares outstanding that could potentially dilute basic EPS. Basis of Presentation Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Use of Estimates in the Preparation of the Condensed Consolidated Financial Statements Use of Estimates, Policy [Policy Text Block] Recently Adopted and Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Geographical [Domain] Non-US [Member] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Transferred over Time [Member] Transferred over Time [Member] Transferred at Point in Time [Member] Transferred at Point in Time [Member] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Manufacturing [Member] Manufacturing [Member] Manufacturing business Healthcare [Member] Health Care [Member] Contract with Customer, Duration [Axis] Contract with Customer, Duration [Axis] Contract with Customer, Duration [Domain] Contract with Customer, Duration [Domain] Long-term Contract with Customer [Member] Long-term Contract with Customer [Member] Revenue Source [Axis] Revenue Source [Axis] Revenue Source [Axis} Revenue Source [Domain] Revenue Source [Domain] [Domain] for Revenue Source [Axis} Advertising Revenue [Member] Advertising Revenue [Member] Advertising Revenue [Member] Retransmission Revenue [Member] Retransmission Revenue [Member] Retransmission Revenue [Member] Other Healthcare Services [Member] Other Healthcare Services [Member] Other Healthcare Services [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Percentage of Revenue Percentage of Revenue from Contract with Customer, Excluding Assessed Tax Percentage of Revenue Recognized During Period from Contract with Customer, Excluding Assessed Tax Number of Performance Obligations Number of Performance Obligations Number of Performance Obligations in standard contract Number of Performance Obligations In Contract With Tuition Cap Number of Performance Obligations In Contract With Tuition Cap Number of Performance Obligations In Contract With Tuition Cap Maximum Term of Contract Maximum Term of Contract Maximum Term of Contract Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount 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 Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Revenue Recognition, Maximum Period between Recognition of Revenue and Receipt of Payment Revenue Recognition, Maximum Period between Recognition of Revenue and Receipt of Payment Revenue Recognition, Maximum Period between Recognition of Revenue and Receipt of Payment Number of Business Lines Number of Business Lines The number of business lines. Minimum Term of Contract Minimum Term of Contract Minimum Term of Contract Deferred revenue recognized in period related to beginning balance Deferred Revenue, Revenue Recognized Costs amortized during the period Capitalized Contract Cost, Amortization Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Summary of Other Comprehensive (Loss) Income Comprehensive Income (Loss) [Table Text Block] Summary of Changes in Accumulated Other Comprehensive (Loss) Income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Summary of Amounts and Line Items of Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Other Indebtedness [Member] Other Indebtedness [Member] Other Indebtedness [Member] USD $200 million portion of revolver [Member] USD $200 million portion of revolver [Member] USD $200 million portion of revolver [Member] Multicurrency $100 million portion of revolver [Member] Multicurrency $100 million portion of revolver [Member] Multicurrency $100 million portion of revolver [Member] Securities Subject to Mandatory Redemption [Member] Securities Subject to Mandatory Redemption [Member] Interest Rate Swap [Member] Interest Rate Swap [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Federal Funds Effective Swap Rate [Member] Federal Funds Effective Swap Rate [Member] Eurodollar [Member] Eurodollar [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Debt Issuance Costs, Net Interest rate Debt Instrument, Interest Rate, Stated Percentage Maturity year Debt Instrument, Maturity Date Debt Instrument, Face Amount Debt Instrument, Face Amount Redemption of Notes Outstanding Extinguishment of Debt, Amount Credit facility current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Applicable interest rate margin Debt Instrument, Basis Spread on Variable Rate Debt covenant net leverage ratio, maximum Debt Instrument, Covenant, Net Leverage Ratio, Maximum Maximum net leverage ratio required to be maintained under Credit Agreement. Debt covenant interest coverage ratio, minimum Debt Instrument, Covenant, Interest Coverage Ratio, Minimum Minimum consolidated interest coverage ratio based upon the ratio of consolidated adjusted EBITDA to consolidated interest expense as determined pursuant to the Credit Agreement. Total fixed interest rate Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate Average borrowings outstanding Average Outstanding Debt Amount Average borrowings outstanding during the period, both short and long term. Weighted average interest rate of borrowings Debt Instrument, Interest Rate During Period Net interest expense incurred Interest Expense, Debt Interest expense Fair value of debt instrument Debt Instrument, Fair Value Disclosure Carrying value of debt instrument Term of debt instrument Debt Instrument, Term Borrowings outstanding Income Taxes Income Tax Disclosure [Text Block] Changes in Carrying Amount of Goodwill Schedule of Goodwill [Table Text Block] Other Intangible Assets Schedule of Finite and Indefinite Lived Intangible Assets [Table Text Block] Schedule of Finite and Indefinite Lived Intangible Assets [Table Text Block] Other Intangible Assets [Member] Series of Individually Immaterial Business Acquisitions [Member] Series of Individually Immaterial Business Acquisitions [Member] Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Inventory Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Goodwill Indefinite-lived intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets Amortized intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets Amount of other assets acquired at the acquisition date. Other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Deferred income tax liability Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Redeemable noncontrolling interest Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value Aggregate purchase price, net of cash acquired Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest, Net Of Cash Received Amount recognized as of the acquisition date for the assets, including goodwill, in excess of (less than) the aggregate liabilities assumed, less the noncontrolling interest in the acquiree, net of cash received. Total Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest Current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Other noncurrent assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Investments In Affiliates Subsidiaries Associates And Joint Ventures Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Investments In Affiliates Subsidiaries Associates And Joint Ventures Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership, acquired at the acquisition date. Other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other Redeemable noncontrolling interest Inventory, Net of Allowances, Customer Advances and Progress Billings [Abstract] Schedule of Inventories and Contracts in Progress Schedule of Inventory, Current [Table Text Block] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss) [Table] Foreign Currency Translation Adjustment [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Unrealized Gains (Losses) on Available-for-Sale Securities [Member] Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Pension and Other Postretirement Plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Net Prior Service Cost [Member] Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Net Actuarial (Gain) Loss [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Cash Flow Hedge [Member] Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Other Comprehensive Income (Loss) [Line Items] Other Comprehensive Income (Loss) [Line Items] [Line Items] for Other Comprehensive Income (Loss) [Table] Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss) before Reclassifications, Tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from AOCI, Current Period, Tax Reclassification from AOCI, Current Period, Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Other Comprehensive Income (Loss), before tax Other Comprehensive Income (Loss), before Tax Other Comprehensive Income (Loss), income tax Other Comprehensive Income (Loss), Tax Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] 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] Gain on cost method investments Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Loss on write-downs of cost method investments Cost-method Investments, Other than Temporary Impairment Impairment of goodwill Business Segments Segment Reporting Disclosure [Text Block] Gain on marketable equity securities, net Plus: Net losses in earnings from marketable equity securities sold Equity Securities, FV-NI, Realized Gain (Loss) Net unrealized gains in earnings from marketable equity securities still held at the end of the period Equity Securities, FV-NI, Unrealized Gain (Loss) Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] 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. 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] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Defined Benefit Plan Assets Total [Member] Defined Benefit Plan Assets Total [Member] -- None. No documentation exists for this element. -- Foreign Investments [Member] Foreign Investments [Member] Information about the entity's defined pension plan foreign investments. Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Berkshire Hathaway Common Stock [Member] Early Retirment Program Expense [Axis] Early Retirment Program Expense [Axis] -- None. No documentation exists for this element. -- Early Retirement Program Expense [Domain] Early Retirement Program Expense [Domain] -- None. No documentation exists for this element. -- Special Incentive Program [Member] Special Incentive Program [Member] Special Incentive Program [Member] Voluntary Retirement Incentive Program [Member] Voluntary Retirement Incentive Program [Member] -- None. No documentation exists for this element. -- Separation Incentive Program [Member] Separation Incentive Program [Member] Separation Incentive Program [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. Percent of plan assets managed by investment companies Percent Of Plan Assets Managed By Investment Companies The percentage of plan assets managed by investment companies. Number of investment companies actively managing plan assets Number Of Investment Companies Managing Plan Assets The number of investment companies actively managing plan assets. Defined benefit plan, target allocation maximum percentage of assets, singular equity security, without prior approval by plan administrator Defined Benefit Plan Target Allocation Percentage Of Assets Singular Equity Security Limit Without Approval Of Plan Administrator Target allocation maximum percentage of investment in a single equity security to total plan assets without prior approval of plan administrator. Defined benefit plan, target allocation percentage of assets Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Minimum percentage of plan assets considered as significant concentrations in pension plans Concentration Risk, Percentage Number of investments the company's pension plan held which individually exceed 10% of total plan assets Number Of Investments Companys Pension Plan Held Which Individually Exceed 10 Percent Of Total Plan Assets Number Of Investments The Companys Pension Plan Held Which Individually Exceed 10 Percent Of Total Plan Assets Value of investments Investments Percentage of total plan assets Statement of Comprehensive Income [Abstract] Net Income Other Comprehensive (Loss) Income, Before Tax Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Foreign currency translation adjustments: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent [Abstract] Translation adjustments arising during the period Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax Unrealized gains on available-for-sale securities: Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax [Abstract] Unrealized gains for the period, net Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Pension and other postretirement plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Amortization of net prior service cost included in net income Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Amortization of net actuarial gain included in net income Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Total pension and other postretirement plans, before tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Cash flow hedge (loss) gain Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax Other Comprehensive (Loss) Income, Before Tax Income tax benefit (expense) related to items of other comprehensive (loss) income Other Comprehensive (Loss) Income, Net of Tax Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Total Comprehensive Income Attributable to Graham Holdings Company Comprehensive Income (Loss), Net of Tax, Attributable to Parent Disposal Groups, Including Discontinued Operations [Table] Disposal Group, Not Discontinued Operation, Revenue Disposal Group, Not Discontinued Operation, Revenue Amount of revenue attributable to disposal group. Excludes discontinued operations. Disposal Group, Not Discontinued Operation, Operating Income Disposal Group, Not Discontinued Operation, Operating Income (Loss) Amount of operating income (loss) attributable to disposal group. Excludes discontinued operations. Raw materials Inventory, Raw Materials, Net of Reserves Work-in-process Inventory, Work in Process, Net of Reserves Finished goods Inventory, Finished Goods, Net of Reserves Contracts in progress Inventory for Long-term Contracts or Programs, Gross Inventories and contracts in progress Schedule of assets acquired and liabilities assumed Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Acquisition Pro Forma Financial Information Business Acquisition, Pro Forma Information [Table Text Block] Information related to 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. Debt Debt Disclosure [Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Accounting Standards Update 2017-07 [Member] Accounting Standards Update 2017-07 [Member] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] Previously Reported [Member] Previously Reported [Member] Restatement Adjustment [Member] Restatement Adjustment [Member] Operating expenses Selling, General and Administrative Expenses Non-operating pension and postretirement benefit income Income before income taxes Schedule of Investments [Table] Schedule of Investments [Table] Intersection Holdings [Member] Intersection [Member] Intersection Holdings,LLC [Member] York Joint Venture [Member] York Joint Venture [Member] York Joint Venture [Member] Earnings of two investments [Member] Two investments [Member] Two investments [Member] KIHL [Member] KIHL [Member] KIHL [Member] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Money Market Investments Money Market Funds, at Carrying Value Payments to Acquire Marketable Securities Payments to Acquire Marketable Securities Document Fiscal Year Focus Document Fiscal Year Focus Cumulative Realized Gain (Loss) on Marketable securities Marketable Securities, Realized Gain (Loss) Proceeds from sales of marketable equity securities Proceeds from Sale and Maturity of Marketable Securities Equity Method Investment, Ownership Percentage Revenue from Related Parties Revenue from Related Parties Loan commitment to affiliate Other Commitment Equity Securities without Readily Determinable Fair Value Equity Securities without Readily Determinable Fair Value, Amount Advances to Affiliate Advances to Affiliate 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. Loan Receivable Fixed Interest Rate Related Party Transaction, Rate Number of shares held in investment Number Of Shares Held In Investment The number of shares held in an investment. Impairment loss on cost method investments Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock Option Plan [Member] Employee Stock Option [Member] Restricted Stock Awards [Member] Restricted Stock [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 Dividends declared per common share Common Stock, Dividends, Per Share, Declared Earnings Per Share Earnings Per Share [Text Block] Impairment of cost method investments Impairment of cost method investments Gain (loss) on sales of businesses Gain on sale of a cost method investment Cost-method Investments, Realized Gain (Loss) Gain on sale of land Gain (Loss) on Disposition of Property Plant Equipment Foreign currency (loss) gain, net Foreign Currency Transaction Gain (Loss), before Tax Other, net Other Nonoperating Gains (Losses) Total Other Non-Operating Income Additional gain on sale of Classified Ventures Equity Method Investment, Realized Gain (Loss) on Disposal Weighted average restricted stock Antidilutive Restricted Stock Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of restricted stock using the treasury stock method. Weighted average stock options Antidilutive Options Additional shares excluded in the calculation of diluted EPS as a result of the antidilutive effect of options using the treasury stock method. Capitalized Contract Cost [Abstract] Capitalized Contract Cost [Table] Capitalized Contract Cost [Table] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Domain] Capitalized Contract Cost [Domain] Capitalized Contract Cost [Line Items] Capitalized Contract Cost [Line Items] Contract costs capitalized during the period Contract Costs Capitalized During the Period Capitalized contract costs associated with new contracts entered into during the period. Change in capitalized contract cost, other Change in Capitalized Contract Cost, Other Change in capitalized contract cost, other Balance of costs to obtain a contract Capitalized Contract Cost, Net Statement of Cash Flows [Abstract] Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, amortization and goodwill and other long-lived asset impairment Depreciation, Depletion, Amortization And Impairment The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets, including write-downs for impairments. Depreciation and amortization Depreciation, Depletion and Amortization Net pension benefit Net Periodic Benefit For Defined Benefit Pension Plans Excluding Early Retirement Program, Special Separation Benefit Expense And Settlement Including Spinoff Curtailment 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. This element includes the curtailment related to the spin-off of a business. Early retirement program expense Gain on marketable equity securities and cost method investments, net Unrealized Gain (Loss) on Investments Stock-based compensation expense, net Share-based Compensation (Gain) loss on disposition of businesses, property, plant and equipment and investments, net Gain (Loss) on Disposition of Assets Debt extinguishment costs Gain (Loss) on Extinguishment of Debt, before Write off of Debt Issuance Cost Foreign exchange loss (gain) Write-down of cost method investments Write-down of cost method investments Gain on sale of equity affiliate Equity in earnings of affiliates, net of distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions (Benefit) provision for deferred income taxes Deferred Income Tax Expense (Benefit) Change in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable, net Increase (Decrease) in Accounts Receivable Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Deferred revenue Increase (Decrease) in Deferred Revenue Income taxes receivable Increase (Decrease) in Income Taxes Other assets and other liabilities, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Other Other Operating Activities, Cash Flow Statement Net Cash Provided by Operating Activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Investments in certain businesses, net of cash acquired Proceeds from sales of marketable equity securities Proceeds from Sale of Available-for-sale Securities, Equity Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Advance related to Kaplan University transaction Advance related to Kaplan University transaction and loan to affiliate AdvanceRelatedToKaplanUniversityTransactionAndLoanToAffiliate Payments made for advance related to Kaplan University transaction and loan to affiliate. Net (payments) proceeds from disposition of businesses, 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. Investments in equity affiliates, cost method and other investments Payments To Acquire Equity Method Cost Method Investments And Other Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence, cost method investments or other investments, not including marketable equity securities. Return of investment in equity affiliates Proceeds from Equity Method Investment, Distribution, Return of Capital Investments in equity affiliates and cost method investments Payments To Acquire Equity Method And Cost Method Investments The cash outflow associated with the purchase of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence or cost method investments. Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Repayments of borrowings Proceeds from (Repayments of) Debt Repayments of borrowings Repayments of Long-term Debt Repayments of borrowings and early redemption premium RepaymentsOfLongTermDebtAndDebtExtinguishmentCosts The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer and for cost from early extinguishment of debt, which includes only the premium paid. Issuance of borrowings Proceeds from Issuance of Long-term Debt Common shares repurchased Payments for Repurchase of Common Stock Dividends paid Payments of Ordinary Dividends Purchase of noncontrolling interest Payments for Repurchase of Redeemable Noncontrolling Interest Payments of debt financing costs Payments of Financing Costs Proceeds from exercise of stock options Proceeds from Stock Options Exercised Deferred payments of acquisition and noncontrolling interest Deferred Payments Of Acquisition And Noncontrolling Interest Deferred payments made related to acquisitions and noncontrolling interest. Other Proceeds from (Payments for) Other Financing Activities Net Cash Used in Financing Activities Net Cash Provided by (Used in) Financing Activities Effect Of Currency Exchange Rate Change Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Net Decrease in Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Beginning Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Ending Cash and Cash Equivalents and Restricted Cash Organization, Basis of Presentation and Recent Accounting Pronouncements Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Investments in Marketable Equity Securities Marketable Securities [Table Text Block] Gain on Marketable Equity Securities Gain (Loss) on Securities [Table Text Block] Inventories and Contracts in Progress Inventory Disclosure [Text Block] Summary of Segment Reporting Information, by Operating Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Contingencies Commitments and Contingencies Disclosure [Text Block] Receivable from contracts with customers, less doubtful accounts Accounts Receivable, Net, Current Other Receivables Other Receivables Accounts receivable, net Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable 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. Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items] Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items] [Line Items] for Disclosures pertaining to an entity's basic and diluted earnings per share. Net income attributable to Graham Holdings Company common stockholders Less: Dividends paid-common stock outstanding and unvested restricted shares Dividends Paid Common Stock And Share-based Compensation-Cash Amount of paid and unpaid common stock dividends declared with the form of settlement in cash and amount of paid and unpaid cash dividends declared and applicable to holders of share-based compensation, for example, but not limited to, non-vested shares, stock options, or restricted stock units. Undistributed earnings Undistributed Earnings, Basic Percent allocated to common stockholders Percentage Of Undistributed Earnings Allocated To Common Stockholders Represents the percentage allocation of undistributed earnings to common stockholders. Undistributed Earnings Allocated To Common Stockholders Undistributed Earnings Allocated To Common Stockholders The earnings that is allocated to common stock to the extend that each stockholder may share in the earnings as if all the earnings for the period has been distributed. Add: Dividends paid-common stock outstanding Dividends, Common Stock, Cash Numerator for basic earnings per share Net Income (Loss) Available to Common Stockholders, Basic Add: Additional undistributed earnings due to dilutive stock options Additional Undistributed Earnings Due To Dilutive Stock Options The earnings that is allocated to common stock due to the dilutive effect of stock options in diluted earnings per share. Numerator for diluted earnings per share Net Income (Loss) Available to Common Stockholders, Diluted Weighted average shares outstanding (shares) Add: Effect of dilutive stock options (shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Denominator for diluted earnings per share (shares) Weighted Average Number of Shares Outstanding, Diluted Graham Holdings Company Common Stockholders: Income Per Share From Continuing Operations To Common Stockholders [Abstract] Income Per Share From Continuing Operations To Common Shareholders. Basic income per common share in dollars per share Diluted income per common share in dollars per share Summary of non-operating income Schedule of Other Nonoperating Income (Expense) [Table Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Class A Common Stock [Member] Common Class A [Member] Class B Common Stock [Member] Common Class B [Member] Document Type Amendment Flag Document Period End Date Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Stock, Shares Outstanding Statement of Financial Position [Abstract] Assets Assets [Abstract] Current Assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash and Cash Equivalents 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. Income taxes receivable Income Taxes Receivable, Current Total Current Assets Assets, Current Property, Plant and Equipment, Net Property, Plant and Equipment, Net Goodwill, Net Amortized Intangible Assets, Net Deferred Income Taxes Deferred Tax Assets, Net Liabilities and Equity Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Income taxes payable Accrued Income Taxes, Current Current portion of long-term debt Dividends declared Dividends Payable, Current Total Current Liabilities Liabilities, Current Postretirement Benefits Other Than Pensions Liability, Other Postretirement Defined Benefit Plan, Noncurrent Accrued Compensation and Related Benefits Deferred Compensation Liability, Classified, Noncurrent Other Liabilities Other Liabilities, Noncurrent Deferred Income Taxes Deferred Tax Liabilities, Net Mandatorily Redeemable Noncontrolling Interest Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount, Noncurrent Long-Term Debt Total Liabilities Liabilities Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest, Equity, Carrying Amount Preferred Stock Preferred Stock, Value, Issued Common Stockholders’ Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock Common Stock, Value, Issued Capital in excess of par value Additional Paid in Capital Accumulated other comprehensive income (loss), net of tax Cumulative foreign currency translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Unrealized gain on available-for-sale securities Accumulated Other Comprehensive Income (Loss), Debt Securities, Available-for-sale, Adjustment, after Tax Unrealized gain on pensions and other postretirement plans Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Cash flow hedge Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Cost of Class B common stock held in treasury Treasury Stock, Value Total Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total Liabilities and Equity Liabilities and Equity Acquisitions and Dispositions of Businesses Mergers, Acquisitions and Dispositions Disclosures [Text Block] Disaggregation of Revenue [Abstract] Education Intersegment Eliminations [Member] Education Intersegment Eliminations [Member] Education Intersegment Eliminations Business Intersegment Eliminations [Domain] Revenue Revenue from Contract with Customer, Excluding Assessed Tax Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Accumulated Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Unrealized Gain on Available-for-Sale Securities [Member] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassifications, before tax Provision for Income Tax Reclassifications, net of tax Net of Tax Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] AOCI Including Portion Attributable to Noncontrolling Interest [Member] AOCI Including Portion Attributable to Noncontrolling Interest [Member] Cumulative Foreign Currency Translation Adjustment [Member] Unrealized Gain on Pensions and Other Postretirement Plans [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Accumulated Other Comprehensive Income (Loss), beginning balance Reclassification from accumulated other comprehensive income to retained earnings as a result of adoption of new guidance Reclassification From Accumulated Other Comprehensive Income To Retained Earnings Reclassification from accumulated other comprehensive income to retained earnings Other comprehensive (loss) income before reclassifications Net amount reclassified from accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), ending balance Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Marketable equity securities Other current investments Other Short-term Investments Interest Rate Swap Interest Rate Cash Flow Hedge Asset at Fair Value Total Financial Assets Investments, Fair Value Disclosure Liabilities Liabilities [Abstract] Deferred compensation plan liabilities Deferred Compensation Liability, Current and Noncurrent Interest rate swap Interest Rate Cash Flow Hedge Liability at Fair Value Mandatorily redeemable noncontrolling interest Mandatorily Redeemable Noncontrolling Interest Fair Value Disclosure Fair value of the Noncontrolling interest that an entity is required to redeem for cash or other assets at a fixed or determinable date or upon the occurrence of an event. Total Financial Liabilities Financial Liabilities Fair Value Disclosure Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Contract with Customer, Liability [Abstract] Contract with Customer, Asset and Liability Contract with Customer, Asset and Liability [Table Text Block] Capitalized Contract Cost Capitalized Contract Cost [Table Text Block] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Table] Schedule of Non-Operating Income (Expense) [Line Items] Schedule of Non-Operating Income (Expense) [Line Items] [Line Items] for Schedule of Non-Operating Income (Expense) [Table]