$GHC
Graham Holdings Co Stock $ghc

$ghc Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000010488921000018 Filed on February 24, 2021

Income Statement

Concept	2020 Q4	2019 Q4	2019 Q3
Revenue	$787.0M	$763.5M	$738.8M
YoY Change	3.08%	10.8%	9.49%
Cost Of Revenue	$493.8M	$524.3M	$517.9M
YoY Change	-5.82%	21.17%	15.37%
Gross Profit	$293.2M	$239.2M	$220.9M
YoY Change	22.58%	-6.71%	-2.17%
Gross Profit Margin	37.25%	31.33%	29.9%
Selling, General & Admin	$216.3M	$170.6M	$175.3M
YoY Change	26.79%	11.8%	33.71%
% of Gross Profit	73.77%	71.32%	79.36%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$16.16M	$16.50M	$15.35M
YoY Change	-2.04%	11.35%	12.48%
% of Gross Profit	5.51%	6.9%	6.95%
Operating Expenses	$246.7M	$200.8M	$204.2M
YoY Change	22.86%	11.06%	30.06%
Operating Profit	$46.20M	$30.31M	$16.27M
YoY Change	52.42%	-59.9%	-73.22%
Interest Expense	$16.01M	$7.192M	$6.776M
YoY Change	122.58%	10.12%	10.45%
% of Operating Profit	34.65%	23.73%	41.65%
Other Income/Expense, Net	$203.5M	-$3.704M	$5.556M
YoY Change	-5594.71%	-70.51%	76.83%
Pretax Income	$317.7M	$185.1M	$58.17M
YoY Change	71.64%	167.75%	-56.94%
Income Tax	$80.80M	$39.10M	$15.20M
% Of Pretax Income	25.43%	21.12%	26.13%
Net Earnings	$237.1M	$145.9M	$43.15M
YoY Change	62.56%	157.35%	-65.5%
Net Earnings / Revenue	30.13%	19.11%	5.84%
Basic Earnings Per Share	$47.45	$27.45	$8.12
Diluted Earnings Per Share	$47.34	$27.25	$8.05
COMMON SHARES
Basic Shares Outstanding	4.970M shares	5.284M shares	5.285M shares
Diluted Shares Outstanding			5.329M shares

Balance Sheet

Concept	2020 Q4	2019 Q4	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$1.002B	$800.1M	$696.5M
YoY Change	25.18%	4.21%	-11.06%
Cash & Equivalents	$414.0M	$200.2M	$142.3M
Short-Term Investments	$587.6M	$600.0M	$554.2M
Other Short-Term Assets	$942.0K	$1.400M	$87.86M
YoY Change	-32.71%	-98.31%	12.84%
Inventory	$120.6M	$108.9M	$113.2M
Prepaid Expenses	$75.52M	$92.29M
Receivables	$519.6M	$595.3M	$582.9M
Other Receivables	$46.90M	$39.70M	$38.70M
Total Short-Term Assets	$1.774B	$1.663B	$1.534B
YoY Change	6.66%	8.56%	-0.1%
LONG-TERM ASSETS
Property, Plant & Equipment	$378.3M	$384.7M	$370.9M
YoY Change	-1.66%	31.25%	36.57%
Goodwill	$1.485B	$1.388B	$1.345B
YoY Change	6.95%	6.98%	2.7%
Intangibles
YoY Change
Long-Term Investments	$155.8M	$162.2M	$164.0M
YoY Change	-3.96%	12.8%	14.85%
Other Assets	$146.8M	$128.5M	$129.5M
YoY Change	14.24%	9.04%	10.5%
Total Long-Term Assets	$4.670B	$4.268B	$3.953B
YoY Change	9.42%	32.06%	18.44%
TOTAL ASSETS
Total Short-Term Assets	$1.774B	$1.663B	$1.534B
Total Long-Term Assets	$4.670B	$4.268B	$3.953B
Total Assets	$6.444B	$5.931B	$5.488B
YoY Change	8.65%	24.5%	12.6%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$106.2M	$507.7M	$477.5M
YoY Change	-79.08%	4.34%	6.54%
Accrued Expenses	$86.80M	$92.70M	$78.10M
YoY Change	-6.36%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$6.452M	$82.18M	$81.70M
YoY Change	-92.15%	1184.05%	1137.88%
Total Short-Term Liabilities	$949.6M	$1.042B	$989.0M
YoY Change	-8.85%	28.28%	22.97%
LONG-TERM LIABILITIES
Long-Term Debt	$506.1M	$430.7M	$420.5M
YoY Change	17.52%	-8.52%	-11.1%
Other Long-Term Liabilities	$48.77M	$27.22M	$27.40M
YoY Change	79.14%	-52.98%	-53.77%
Total Long-Term Liabilities	$554.9M	$457.9M	$447.9M
YoY Change	21.18%	-13.39%	-15.85%
TOTAL LIABILITIES
Total Short-Term Liabilities	$949.6M	$1.042B	$989.0M
Total Long-Term Liabilities	$554.9M	$457.9M	$447.9M
Total Liabilities	$2.666B	$2.599B	$2.425B
YoY Change	2.58%	41.02%	28.05%
SHAREHOLDERS EQUITY
Retained Earnings	$6.805B	$6.534B	$6.389B
YoY Change	4.14%	4.78%	3.38%
Common Stock	$20.00M	$20.00M	$20.00M
YoY Change	0.0%	0.0%	0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$4.057B	$3.920B	$3.918B
YoY Change	3.49%	-0.05%	0.11%
Treasury Stock Shares
Shareholders Equity	$3.759B	$3.319B	$3.052B
YoY Change
Total Liabilities & Shareholders Equity	$6.444B	$5.931B	$5.488B
YoY Change	8.65%	24.5%	12.6%

Cashflow Statement

Concept	2020 Q4	2019 Q4	2019 Q3
OPERATING ACTIVITIES
Net Income	$237.1M	$145.9M	$43.15M
YoY Change	62.56%	157.35%	-65.5%
Depreciation, Depletion And Amortization	$16.16M	$16.50M	$15.35M
YoY Change	-2.04%	11.35%	12.48%
Cash From Operating Activities	-$30.20M	$92.90M	$89.00M
YoY Change	-132.51%	-2.31%	-26.69%
INVESTING ACTIVITIES
Capital Expenditures	-$13.50M	-$17.80M	-$23.00M
YoY Change	-24.16%	-54.71%	25.0%
Acquisitions
YoY Change
Other Investing Activities	$200.2M	-$16.50M	-$78.50M
YoY Change	-1313.33%	-59.16%	-11.6%
Cash From Investing Activities	$186.7M	-$34.20M	-$101.6M
YoY Change	-645.91%	-57.09%	-5.22%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-50.30M	-6.900M	-14.70M
YoY Change	628.99%	-72.62%	-63.52%
NET CHANGE
Cash From Operating Activities	-30.20M	92.90M	89.00M
Cash From Investing Activities	186.7M	-34.20M	-101.6M
Cash From Financing Activities	-50.30M	-6.900M	-14.70M
Net Change In Cash	106.2M	51.80M	-27.30M
YoY Change	105.02%	-628.57%	4.6%
FREE CASH FLOW
Cash From Operating Activities	-$30.20M	$92.90M	$89.00M
Capital Expenditures	-$13.50M	-$17.80M	-$23.00M
Free Cash Flow	-$16.70M	$110.7M	$112.0M
YoY Change	-115.09%	-17.63%	-19.89%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0000104889
CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Annual Report DocumentAnnualReport	true
CY2020	dei	Document Period End Date DocumentPeriodEndDate	2020-12-31
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020	dei	Entity File Number EntityFileNumber	001-06714
CY2020	dei	Entity Registrant Name EntityRegistrantName	Graham Holdings Co
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	53-0182885
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	1300 North 17th Street
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Arlington
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	VA
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	22209
CY2020	dei	City Area Code CityAreaCode	703
CY2020	dei	Local Phone Number LocalPhoneNumber	345-6300
CY2020	dei	Security12b Title Security12bTitle	Class B Common Stock, par value$1.00 per share
CY2020	dei	Trading Symbol TradingSymbol	GHC
CY2020	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2020	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2020	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2020	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2020	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2020	dei	Entity Small Business EntitySmallBusiness	false
CY2020	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2020	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2020	dei	Entity Shell Company EntityShellCompany	false
CY2020Q2	dei	Entity Public Float EntityPublicFloat	1400000000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2889121000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2932099000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2695966000	USD
CY2020	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	715401000	USD
CY2019	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	717659000	USD
CY2018	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	750926000	USD
CY2020	us-gaap	Depreciation Depreciation	74257000	USD
CY2019	us-gaap	Depreciation Depreciation	59253000	USD
CY2018	us-gaap	Depreciation Depreciation	56722000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	56780000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	53243000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	47414000	USD
CY2020	us-gaap	Asset Impairment Charges AssetImpairmentCharges	30170000	USD
CY2019	us-gaap	Asset Impairment Charges AssetImpairmentCharges	9152000	USD
CY2018	us-gaap	Asset Impairment Charges AssetImpairmentCharges	8109000	USD
CY2020	us-gaap	Costs And Expenses CostsAndExpenses	2788714000	USD
CY2019	us-gaap	Costs And Expenses CostsAndExpenses	2787553000	USD
CY2018	us-gaap	Costs And Expenses CostsAndExpenses	2449805000	USD
CY2020	us-gaap	Operating Income Loss OperatingIncomeLoss	100407000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	144546000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	246161000	USD
CY2020	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	6664000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	11664000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	14473000	USD
CY2020	us-gaap	Investment Income Interest InvestmentIncomeInterest	3871000	USD
CY2019	us-gaap	Investment Income Interest InvestmentIncomeInterest	6151000	USD
CY2018	us-gaap	Investment Income Interest InvestmentIncomeInterest	5353000	USD
CY2020	us-gaap	Interest Expense InterestExpense	38310000	USD
CY2019	us-gaap	Interest Expense InterestExpense	29779000	USD
CY2018	us-gaap	Interest Expense InterestExpense	37902000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-11378000	USD
CY2020	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-59315000	USD
CY2019	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-162798000	USD
CY2018	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-120541000	USD
CY2020	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	60787000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	98668000	USD
CY2018	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-15843000	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	214534000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	32431000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2103000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	407268000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	426479000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	323508000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	107300000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	98600000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52100000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	299968000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	327879000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	271408000	USD
CY2020	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	-397000	USD
CY2019	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	24000	USD
CY2018	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	202000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	300365000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	327855000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	271206000	USD
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	58.30
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	61.70
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	50.55
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5124000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5285000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5333000	shares
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	58.13
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	61.21
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	50.20
CY2020	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5139000	shares
CY2019	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5327000	shares
CY2018	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5370000	shares
CY2020	us-gaap	Profit Loss ProfitLoss	299968000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	327879000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	271408000	USD
CY2020	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax	31642000	USD
CY2019	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax	5371000	USD
CY2018	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax	-35584000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Reclassification Adjustment From Aoci Realized Upon Sale Or Liquidation Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Reclassification Adjustment From Aoci Realized Upon Sale Or Liquidation Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationBeforeTax	-2011000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Reclassification Adjustment From Aoci Realized Upon Sale Or Liquidation Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	31642000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	7382000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Before Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax	-35584000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	365164000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	231104000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-101013000	USD
CY2020	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Cost Credit Arising During Period Before Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax	69000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Cost Credit Arising During Period Before Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax	5725000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Cost Credit Arising During Period Before Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax	-4262000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-1219000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	2046000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	11349000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	2680000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-4142000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-947000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Finalization Of Pension And Non Pension Postretirement Plan Valuation Before Tax OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Finalization Of Pension And Non Pension Postretirement Plan Valuation Before Tax OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax	-91676000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Finalization Of Pension And Non Pension Postretirement Plan Valuation Before Tax OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax	-30267000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-368994000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-127515000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	139314000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	-1282000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax	-1344000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	551000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	399354000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	133553000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-174347000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	99335000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	34087000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-37510000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	300019000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	99466000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-136837000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	599987000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	427345000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	134571000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-397000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	24000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	202000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	600384000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	427321000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	134369000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	413991000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	200165000	USD
CY2020Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	9063000	USD
CY2019Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	13879000	USD
CY2020Q4	ghc	Investments In Marketable Equity Securities And Other Investments InvestmentsInMarketableEquitySecuritiesAndOtherInvestments	587582000	USD
CY2019Q4	ghc	Investments In Marketable Equity Securities And Other Investments InvestmentsInMarketableEquitySecuritiesAndOtherInvestments	599967000	USD
CY2020Q4	us-gaap	Accounts And Other Receivables Net Current AccountsAndOtherReceivablesNetCurrent	537156000	USD
CY2019Q4	us-gaap	Accounts And Other Receivables Net Current AccountsAndOtherReceivablesNetCurrent	624216000	USD
CY2020Q4	us-gaap	Inventory Net Of Allowances Customer Advances And Progress Billings InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings	120622000	USD
CY2019Q4	us-gaap	Inventory Net Of Allowances Customer Advances And Progress Billings InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings	120834000	USD
CY2020Q4	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	75523000	USD
CY2019Q4	us-gaap	Prepaid Expense Current PrepaidExpenseCurrent	92289000	USD
CY2020Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	29313000	USD
CY2019Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	10735000	USD
CY2020Q4	us-gaap	Other Assets Current OtherAssetsCurrent	942000	USD
CY2019Q4	us-gaap	Other Assets Current OtherAssetsCurrent	1400000	USD
CY2020Q4	us-gaap	Assets Current AssetsCurrent	1774192000	USD
CY2019Q4	us-gaap	Assets Current AssetsCurrent	1663485000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	378286000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	384670000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	462560000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	526417000	USD
CY2020Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	155777000	USD
CY2019Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	162249000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	1484750000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	1388279000	USD
CY2020Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	120437000	USD
CY2019Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	140197000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	204646000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	233481000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	1708305000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	1292350000	USD
CY2020Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	8396000	USD
CY2019Q4	us-gaap	Deferred Income Tax Assets Net DeferredIncomeTaxAssetsNet	11629000	USD
CY2020Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	146770000	USD
CY2019Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	128479000	USD
CY2020Q4	us-gaap	Assets Assets	6444119000	USD
CY2019Q4	us-gaap	Assets Assets	5931236000	USD
CY2020Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	520236000	USD
CY2019Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	507701000	USD
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CY2019Q4	us-gaap	Deferred Revenue Current DeferredRevenueCurrent	355156000	USD
CY2020Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	5140000	USD
CY2019Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	4121000	USD
CY2020Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	86797000	USD
CY2019Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	92714000	USD
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CY2019Q4	us-gaap	Debt Current DebtCurrent	82179000	USD
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CY2020Q4	us-gaap	Deferred Compensation Liability Classified Noncurrent DeferredCompensationLiabilityClassifiedNoncurrent	201918000	USD
CY2019Q4	us-gaap	Deferred Compensation Liability Classified Noncurrent DeferredCompensationLiabilityClassifiedNoncurrent	193836000	USD
CY2020Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	48768000	USD
CY2019Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	27223000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	521274000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	427372000	USD
CY2020Q4	us-gaap	Shares Subject To Mandatory Redemption Settlement Terms Amount Noncurrent SharesSubjectToMandatoryRedemptionSettlementTermsAmountNoncurrent	9240000	USD
CY2019Q4	us-gaap	Shares Subject To Mandatory Redemption Settlement Terms Amount Noncurrent SharesSubjectToMandatoryRedemptionSettlementTermsAmountNoncurrent	829000	USD
CY2020Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	428849000	USD
CY2019Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	477004000	USD
CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	506103000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	430650000	USD
CY2020Q4	us-gaap	Liabilities Liabilities	2665798000	USD
CY2019Q4	us-gaap	Liabilities Liabilities	2598785000	USD
CY2020Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2019Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2020Q4	us-gaap	Redeemable Noncontrolling Interest Equity Carrying Amount RedeemableNoncontrollingInterestEquityCarryingAmount	11928000	USD
CY2019Q4	us-gaap	Redeemable Noncontrolling Interest Equity Carrying Amount RedeemableNoncontrollingInterestEquityCarryingAmount	5655000	USD
CY2020Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1
CY2019Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	1
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CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	977000	shares
CY2019Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2020Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2019Q4	us-gaap	Preferred Stock Value PreferredStockValue	0	USD
CY2020Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	388159000	USD
CY2019Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	381669000	USD
CY2020Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	6804822000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	6534427000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	9754000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-21888000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-595287000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-325921000	USD
CY2020Q4	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	-1727000	USD
CY2019Q4	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	-738000	USD
CY2020Q4	us-gaap	Treasury Stock Value TreasuryStockValue	4056993000	USD
CY2019Q4	us-gaap	Treasury Stock Value TreasuryStockValue	3920152000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	3759302000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	3319239000	USD
CY2020Q4	us-gaap	Minority Interest MinorityInterest	7091000	USD
CY2019Q4	us-gaap	Minority Interest MinorityInterest	7557000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3766393000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3326796000	USD
CY2020Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	6444119000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	5931236000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	299968000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	327879000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	271408000	USD
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CY2019	ghc	Depreciation Depletion Amortization And Impairment DepreciationDepletionAmortizationAndImpairment	121648000	USD
CY2018	ghc	Depreciation Depletion Amortization And Impairment DepreciationDepletionAmortizationAndImpairment	112245000	USD
CY2020	us-gaap	Operating Lease Right Of Use Asset Amortization Expense OperatingLeaseRightOfUseAssetAmortizationExpense	89956000	USD
CY2019	us-gaap	Operating Lease Right Of Use Asset Amortization Expense OperatingLeaseRightOfUseAssetAmortizationExpense	84185000	USD
CY2018	us-gaap	Operating Lease Right Of Use Asset Amortization Expense OperatingLeaseRightOfUseAssetAmortizationExpense	0	USD
CY2020	ghc	Net Periodic Benefit For Defined Benefit Pension Plans Excluding Curtailment NetPeriodicBenefitForDefinedBenefitPensionPlansExcludingCurtailment	-41573000	USD
CY2019	ghc	Net Periodic Benefit For Defined Benefit Pension Plans Excluding Curtailment NetPeriodicBenefitForDefinedBenefitPensionPlansExcludingCurtailment	-137909000	USD
CY2018	ghc	Net Periodic Benefit For Defined Benefit Pension Plans Excluding Curtailment NetPeriodicBenefitForDefinedBenefitPensionPlansExcludingCurtailment	-100948000	USD
CY2020	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	64996000	USD
CY2019	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	103748000	USD
CY2018	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	-4180000	USD
CY2020	ghc	Credit Loss Expense And Provision For Other Receivables CreditLossExpenseAndProvisionForOtherReceivables	10667000	USD
CY2019	ghc	Credit Loss Expense And Provision For Other Receivables CreditLossExpenseAndProvisionForOtherReceivables	22726000	USD
CY2018	ghc	Credit Loss Expense And Provision For Other Receivables CreditLossExpenseAndProvisionForOtherReceivables	10209000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	6348000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	6278000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	6412000	USD
CY2020	us-gaap	Accretion Expense AccretionExpense	2895000	USD
CY2019	us-gaap	Accretion Expense AccretionExpense	0	USD
CY2018	us-gaap	Accretion Expense AccretionExpense	0	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt Before Write Off Of Deferred Debt Issuance Cost GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost	0	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt Before Write Off Of Deferred Debt Issuance Cost GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost	0	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt Before Write Off Of Deferred Debt Issuance Cost GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost	-10563000	USD
CY2020	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-2153000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-1070000	USD
CY2018	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-3844000	USD
CY2020	ghc	Net Gain Loss On Sales And Dispositionof Businesses NetGainLossOnSalesAndDispositionofBusinesses	209787000	USD
CY2019	ghc	Net Gain Loss On Sales And Dispositionof Businesses NetGainLossOnSalesAndDispositionofBusinesses	-1936000	USD
CY2018	ghc	Net Gain Loss On Sales And Dispositionof Businesses NetGainLossOnSalesAndDispositionofBusinesses	8157000	USD
CY2020	ghc	Realized And Unrealized Gain Loss On Equity Method Investments And Equity Securities Without Readily Determinable Fair Value RealizedAndUnrealizedGainLossOnEquityMethodInvestmentsAndEquitySecuritiesWithoutReadilyDeterminableFairValue	-1210000	USD
CY2019	ghc	Realized And Unrealized Gain Loss On Equity Method Investments And Equity Securities Without Readily Determinable Fair Value RealizedAndUnrealizedGainLossOnEquityMethodInvestmentsAndEquitySecuritiesWithoutReadilyDeterminableFairValue	29262000	USD
CY2018	ghc	Realized And Unrealized Gain Loss On Equity Method Investments And Equity Securities Without Readily Determinable Fair Value RealizedAndUnrealizedGainLossOnEquityMethodInvestmentsAndEquitySecuritiesWithoutReadilyDeterminableFairValue	148000	USD
CY2020	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-6592000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	2678000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	10606000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	14377000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	69751000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-7123000	USD
CY2020	ghc	Gain Loss On Sale Or Writedown Of Property Plant Equipment GainLossOnSaleOrWritedownOfPropertyPlantEquipment	-978000	USD
CY2019	ghc	Gain Loss On Sale Or Writedown Of Property Plant Equipment GainLossOnSaleOrWritedownOfPropertyPlantEquipment	1020000	USD
CY2018	ghc	Gain Loss On Sale Or Writedown Of Property Plant Equipment GainLossOnSaleOrWritedownOfPropertyPlantEquipment	1642000	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-61328000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	53602000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-49638000	USD
CY2020	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-3786000	USD
CY2019	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	5317000	USD
CY2018	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	7351000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-32714000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-47069000	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	-44892000	USD
CY2020	us-gaap	Increase Decrease In Deferred Revenue IncreaseDecreaseInDeferredRevenue	-25728000	USD
CY2019	us-gaap	Increase Decrease In Deferred Revenue IncreaseDecreaseInDeferredRevenue	30487000	USD
CY2018	us-gaap	Increase Decrease In Deferred Revenue IncreaseDecreaseInDeferredRevenue	14801000	USD
CY2020	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	3310000	USD
CY2019	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	1828000	USD
CY2018	us-gaap	Increase Decrease In Income Taxes IncreaseDecreaseInIncomeTaxes	9405000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	79743000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	122252000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	26973000	USD
CY2020	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	429000	USD
CY2019	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	233000	USD
CY2018	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	2154000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	210663000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	165164000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	287019000	USD
CY2020	ghc	Net Proceeds From Sale Of Businesses Property Plant And Equipment And Other Assets NetProceedsFromSaleOfBusinessesPropertyPlantAndEquipmentAndOtherAssets	225570000	USD
CY2019	ghc	Net Proceeds From Sale Of Businesses Property Plant And Equipment And Other Assets NetProceedsFromSaleOfBusinessesPropertyPlantAndEquipmentAndOtherAssets	54495000	USD
CY2018	ghc	Net Proceeds From Sale Of Businesses Property Plant And Equipment And Other Assets NetProceedsFromSaleOfBusinessesPropertyPlantAndEquipmentAndOtherAssets	-10344000	USD
CY2020	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	93775000	USD
CY2019	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	19303000	USD
CY2018	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	66741000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	69591000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	93504000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	98192000	USD
CY2020	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	20080000	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	179421000	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	111546000	USD
CY2020	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	20004000	USD
CY2019	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	7499000	USD
CY2018	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	42659000	USD
CY2020	ghc	Payments To Acquire Equity Method Cost Method Investments And Other Investments PaymentsToAcquireEquityMethodCostMethodInvestmentsAndOtherInvestments	12367000	USD
CY2019	ghc	Payments To Acquire Equity Method Cost Method Investments And Other Investments PaymentsToAcquireEquityMethodCostMethodInvestmentsAndOtherInvestments	27529000	USD
CY2018	ghc	Payments To Acquire Equity Method Cost Method Investments And Other Investments PaymentsToAcquireEquityMethodCostMethodInvestmentsAndOtherInvestments	11702000	USD
CY2020	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	506000	USD
CY2019	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	920000	USD
CY2018	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	4799000	USD
CY2020	ghc	Advance Related To Kaplan University Transaction And Loans To Affiliate And Relat Party AdvanceRelatedToKaplanUniversityTransactionAndLoansToAffiliateAndRelatParty	0	USD
CY2019	ghc	Advance Related To Kaplan University Transaction And Loans To Affiliate And Relat Party AdvanceRelatedToKaplanUniversityTransactionAndLoansToAffiliateAndRelatParty	3500000	USD
CY2018	ghc	Advance Related To Kaplan University Transaction And Loans To Affiliate And Relat Party AdvanceRelatedToKaplanUniversityTransactionAndLoansToAffiliateAndRelatParty	28061000	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1562000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	0	USD
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	0	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	199371000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-236735000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-230964000	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	161829000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	2103000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	118030000	USD
CY2020	ghc	Repayments Of Long Term Debt And Debt Extinguishment Costs RepaymentsOfLongTermDebtAndDebtExtinguishmentCosts	83360000	USD
CY2019	ghc	Repayments Of Long Term Debt And Debt Extinguishment Costs RepaymentsOfLongTermDebtAndDebtExtinguishmentCosts	8702000	USD
CY2018	ghc	Repayments Of Long Term Debt And Debt Extinguishment Costs RepaymentsOfLongTermDebtAndDebtExtinguishmentCosts	417159000	USD
CY2020	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	2084000	USD
CY2019	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	41250000	USD
CY2018	us-gaap	Proceeds From Issuance Of Debt ProceedsFromIssuanceOfDebt	400000000	USD
CY2020	us-gaap	Proceeds From Repayments Of Lines Of Credit ProceedsFromRepaymentsOfLinesOfCredit	76241000	USD
CY2019	us-gaap	Proceeds From Repayments Of Lines Of Credit ProceedsFromRepaymentsOfLinesOfCredit	0	USD
CY2018	us-gaap	Proceeds From Repayments Of Lines Of Credit ProceedsFromRepaymentsOfLinesOfCredit	0	USD
CY2020	us-gaap	Payments Of Ordinary Dividends PaymentsOfOrdinaryDividends	29970000	USD
CY2019	us-gaap	Payments Of Ordinary Dividends PaymentsOfOrdinaryDividends	29553000	USD
CY2018	us-gaap	Payments Of Ordinary Dividends PaymentsOfOrdinaryDividends	28617000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	25129000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	481000	USD
CY2018	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	165000	USD
CY2020	ghc	Proceeds From Payments Of Vehicle Floor Plan Payable Net ProceedsFromPaymentsOfVehicleFloorPlanPayableNet	-14160000	USD
CY2019	ghc	Proceeds From Payments Of Vehicle Floor Plan Payable Net ProceedsFromPaymentsOfVehicleFloorPlanPayableNet	14384000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-204002000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	18734000	USD
CY2018	ghc	Proceeds From Payments Of Vehicle Floor Plan Payable Net ProceedsFromPaymentsOfVehicleFloorPlanPayableNet	0	USD
CY2020	ghc	Purchaseof Noncontrolling Interestand Deferred Paymentof Acquisition PurchaseofNoncontrollingInterestandDeferredPaymentofAcquisition	19348000	USD
CY2019	ghc	Purchaseof Noncontrolling Interestand Deferred Paymentof Acquisition PurchaseofNoncontrollingInterestandDeferredPaymentofAcquisition	2805000	USD
CY2018	ghc	Purchaseof Noncontrolling Interestand Deferred Paymentof Acquisition PurchaseofNoncontrollingInterestandDeferredPaymentofAcquisition	16500000	USD
CY2020	us-gaap	Proceeds From Repayments Of Bank Overdrafts ProceedsFromRepaymentsOfBankOverdrafts	1636000	USD
CY2019	us-gaap	Proceeds From Repayments Of Bank Overdrafts ProceedsFromRepaymentsOfBankOverdrafts	-185000	USD
CY2018	us-gaap	Proceeds From Repayments Of Bank Overdrafts ProceedsFromRepaymentsOfBankOverdrafts	-5717000	USD
CY2020	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2019	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	6000000	USD
CY2018	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	USD
CY2020	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	0	USD
CY2019	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	33000	USD
CY2018	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	6501000	USD
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-425000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	0	USD
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	0	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-192359000	USD
CY2020	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2978000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	2766000	USD
CY2018	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-7147000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	209010000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-50071000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-143451000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	214044000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	264115000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	407566000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	423054000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	214044000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	264115000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	91000000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	28000000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	54000000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	31000000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	30000000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	42000000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2915145000	USD
CY2017Q4	us-gaap	Redeemable Noncontrolling Interest Equity Carrying Amount RedeemableNoncontrollingInterestEquityCarryingAmount	4607000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	271408000	USD
CY2018	us-gaap	Net Income Loss Attributable To Redeemable Noncontrolling Interest NetIncomeLossAttributableToRedeemableNoncontrollingInterest	202000	USD
CY2018	us-gaap	Temporary Equity Net Income TemporaryEquityNetIncome	202000	USD
CY2018	us-gaap	Minority Interest Change In Redemption Value MinorityInterestChangeInRedemptionValue	413000	USD
CY2018	ghc	Temporary Equity Changein Redemption Value TemporaryEquityChangeinRedemptionValue	-413000	USD
CY2018	us-gaap	Dividends Common Stock DividendsCommonStock	28617000	USD
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	118030000	USD
CY2018	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	-1485000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	8064000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-136837000	USD
CY2018	us-gaap	Stockholders Equity Other StockholdersEquityOther	0	USD
CY2018	us-gaap	Temporary Equity Other Changes TemporaryEquityOtherChanges	-50000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	2916782000	USD
CY2018Q4	us-gaap	Redeemable Noncontrolling Interest Equity Carrying Amount RedeemableNoncontrollingInterestEquityCarryingAmount	4346000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	327879000	USD
CY2019	us-gaap	Noncontrolling Interest Increase From Subsidiary Equity Issuance NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	6556000	USD
CY2019	ghc	Equity Effectof Acquisitionof Redeemable Noncontrolling Interest EquityEffectofAcquisitionofRedeemableNoncontrollingInterest	0	USD
CY2019	ghc	Acquisitionof Redeemable Noncontrolling Interest AcquisitionofRedeemableNoncontrollingInterest	1715000	USD
CY2019	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2019	us-gaap	Noncontrolling Interest Increase From Business Combination NoncontrollingInterestIncreaseFromBusinessCombination	1153000	USD
CY2019	us-gaap	Net Income Loss Attributable To Redeemable Noncontrolling Interest NetIncomeLossAttributableToRedeemableNoncontrollingInterest	176000	USD
CY2019	us-gaap	Temporary Equity Net Income TemporaryEquityNetIncome	176000	USD
CY2019	us-gaap	Minority Interest Change In Redemption Value MinorityInterestChangeInRedemptionValue	32000	USD
CY2019	ghc	Temporary Equity Changein Redemption Value TemporaryEquityChangeinRedemptionValue	-32000	USD
CY2019	us-gaap	Dividends Common Stock DividendsCommonStock	29553000	USD
CY2019	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	2103000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	239000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6521000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	99466000	USD
CY2019	ghc	Equityeffectofredemptionofredeemablenoncontrollinginterest Equityeffectofredemptionofredeemablenoncontrollinginterest	0	USD
CY2019	us-gaap	Minority Interest Decrease From Redemptions MinorityInterestDecreaseFromRedemptions	550000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3326796000	USD
CY2019Q4	us-gaap	Redeemable Noncontrolling Interest Equity Carrying Amount RedeemableNoncontrollingInterestEquityCarryingAmount	5655000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	299968000	USD
CY2020	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	0	USD
CY2020	ghc	Equity Effectof Acquisitionof Redeemable Noncontrolling Interest EquityEffectofAcquisitionofRedeemableNoncontrollingInterest	0	USD
CY2020	ghc	Acquisitionof Redeemable Noncontrolling Interest AcquisitionofRedeemableNoncontrollingInterest	6005000	USD
CY2020	us-gaap	Net Income Loss Attributable To Redeemable Noncontrolling Interest NetIncomeLossAttributableToRedeemableNoncontrollingInterest	-11000	USD
CY2020	us-gaap	Temporary Equity Net Income TemporaryEquityNetIncome	-11000	USD
CY2020	us-gaap	Minority Interest Change In Redemption Value MinorityInterestChangeInRedemptionValue	273000	USD
CY2020	ghc	Temporary Equity Changein Redemption Value TemporaryEquityChangeinRedemptionValue	279000	USD
CY2020	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	353000	USD
CY2020	us-gaap	Dividends Common Stock DividendsCommonStock	29970000	USD
CY2020	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	161829000	USD
CY2020	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	24577000	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6901000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	300019000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3766393000	USD
CY2020Q4	us-gaap	Redeemable Noncontrolling Interest Equity Carrying Amount RedeemableNoncontrollingInterestEquityCarryingAmount	11928000	USD
CY2020	us-gaap	Nature Of Operations NatureOfOperations	ORGANIZATION AND NATURE OF OPERATIONS<div style="margin-bottom:9pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%">Graham Holdings Company (the Company), is a diversified education and media company. The Company’s Kaplan subsidiary provides a wide variety of educational services, both domestically and outside the United States (U.S.). The Company’s media operations comprise the ownership and operation of seven television broadcasting stations.</span></div><div style="margin-bottom:9pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Education</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%">—Kaplan, Inc. provides an extensive range of educational services for students and professionals. Kaplan’s various businesses comprise three categories: Kaplan International, Higher Education (KHE) and Supplemental Education.</span></div><div style="margin-bottom:9pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Media</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%">—The Company’s diversified media operations comprise television broadcasting, several websites and print publications, podcast content and a marketing solutions provider.</span></div><div style="margin-bottom:9pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:110%">Television broadcasting. </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%">As of December 31, 2020, the Company owned seven television stations located in Houston, TX; Detroit, MI; Orlando, FL; San Antonio, TX; Roanoke, VA; and two stations in Jacksonville, FL. All stations are network-affiliated except for WJXT in Jacksonville, FL.</span></div><div style="margin-bottom:9pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Manufacturing</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%">—The Company’s manufacturing businesses include Hoover, Dekko, Joyce/Dayton and Forney.</span></div><div style="margin-bottom:9pt"><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Other</span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%">—The Company’s other business operations include automotive dealerships, restaurants and entertainment venues, custom framing services and home health and hospice services.</span></div>
CY2020	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Reclassifications. </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%"> Certain amounts in previously issued financial statements have been reclassified to conform with the presentation for the year ended December 31, 2020. The Company disaggregated its operating revenues into sales of services and sales of goods, and also disaggregated the corresponding operating costs into cost of services sold and cost of goods sold. Additionally, the Company reclassified $75.0 million and $100.8 million from cost of services and goods sold (previously operating) to selling, general and administrative in the Consolidated Statement of Operations for the years ended December 31, 2019 and 2018, respectively.</span>
CY2020	us-gaap	Use Of Estimates UseOfEstimates	<span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Use of Estimates. </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%"> The preparation of financial statements in conformity with GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements. Management bases its estimates and assumptions on historical experience and on various other factors that are believed to be reasonable under the circumstances. Due to the inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in those estimates. On an ongoing basis, the Company evaluates its estimates and assumptions.</span>
CY2020	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	<span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:700;line-height:110%">Concentration of Credit Risk. </span><span style="color:#000000;font-family:'Arial',sans-serif;font-size:10pt;font-weight:400;line-height:110%"> Cash and cash equivalents are maintained with several financial institutions domestically and internationally. Deposits held with banks may exceed the amount of insurance provided on such deposits. Generally, these deposits may be redeemed upon demand and are maintained with financial institutions with investment-grade credit ratings. The Company routinely assesses the financial strength of significant customers, and this assessment, combined with the large number and geographical diversity of its customers, limits the Company’s concentration of risk with respect to receivables from contracts with customers.</span>
CY2019	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	304734000	USD
CY2020	ghc	Maximum Termof Contract MaximumTermofContract	P1Y
CY2020	us-gaap	Number Of Businesses Acquired NumberOfBusinessesAcquired	3	business
CY2020	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	96800000	USD
CY2019	us-gaap	Number Of Businesses Acquired NumberOfBusinessesAcquired	8	business
CY2019	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	211800000	USD
CY2019Q4	ghc	Vehicle Floor Plan Facility Payable VehicleFloorPlanFacilityPayable	25800000	USD
CY2019Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	507701000	USD
CY2018	us-gaap	Number Of Businesses Acquired NumberOfBusinessesAcquired	8	business
CY2018	us-gaap	Business Combination Consideration Transferred1 BusinessCombinationConsiderationTransferred1	121100000	USD
CY2020Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Transaction Costs BusinessAcquisitionCostOfAcquiredEntityTransactionCosts	1100000	USD
CY2019Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Transaction Costs BusinessAcquisitionCostOfAcquiredEntityTransactionCosts	3000000.0	USD
CY2018Q4	us-gaap	Business Acquisition Cost Of Acquired Entity Transaction Costs BusinessAcquisitionCostOfAcquiredEntityTransactionCosts	1500000	USD
CY2020Q4	us-gaap	Business Acquisition Purchase Price Allocation Goodwill Expected Tax Deductible Amount BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount	3200000	USD
CY2019Q4	us-gaap	Business Acquisition Purchase Price Allocation Goodwill Expected Tax Deductible Amount BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount	70700000	USD
CY2018Q4	us-gaap	Business Acquisition Purchase Price Allocation Goodwill Expected Tax Deductible Amount BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount	32300000	USD
CY2020	us-gaap	Business Combination Pro Forma Information Revenue Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual	28800000	USD
CY2020	us-gaap	Business Combination Pro Forma Information Earnings Or Loss Of Acquiree Since Acquisition Date Actual BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual	13800000	USD
CY2020	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	2896476000	USD
CY2019	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	3089712000	USD
CY2018	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	3166907000	USD
CY2020	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	293514000	USD
CY2020Q4	us-gaap	Accounts Payable And Accrued Liabilities Current AccountsPayableAndAccruedLiabilitiesCurrent	520236000	USD
CY2018	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	275074000	USD
CY2020Q4	us-gaap	Money Market Funds At Carrying Value MoneyMarketFundsAtCarryingValue	268800000	USD
CY2019Q4	us-gaap	Money Market Funds At Carrying Value MoneyMarketFundsAtCarryingValue	45200000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	232847000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni Cost EquitySecuritiesFvNiCost	282349000	USD
CY2020Q4	ghc	Equity Securities Fvni Accumulated Gross Unrealized Gain EquitySecuritiesFVNIAccumulatedGrossUnrealizedGain	340255000	USD
CY2019Q4	ghc	Equity Securities Fvni Accumulated Gross Unrealized Gain EquitySecuritiesFVNIAccumulatedGrossUnrealizedGain	302731000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	573102000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	585080000	USD
CY2020	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	20000000.0	USD
CY2019	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	7500000	USD
CY2018	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	42700000	USD
CY2020	us-gaap	Marketable Securities Realized Gain Loss MarketableSecuritiesRealizedGainLoss	23000000.0	USD
CY2019	us-gaap	Marketable Securities Realized Gain Loss MarketableSecuritiesRealizedGainLoss	9500000	USD
CY2018	us-gaap	Marketable Securities Realized Gain Loss MarketableSecuritiesRealizedGainLoss	37300000	USD
CY2020	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	93800000	USD
CY2019	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	19300000	USD
CY2018	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	66700000	USD
CY2020	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	60787000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	98668000	USD
CY2018	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-15843000	USD
CY2020	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-13382000	USD
CY2019	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	2810000	USD
CY2018	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-4271000	USD
CY2020	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	74169000	USD
CY2019	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	95858000	USD
CY2018	us-gaap	Equity Securities Fv Ni Unrealized Gain Loss EquitySecuritiesFvNiUnrealizedGainLoss	-11572000	USD
CY2020Q4	us-gaap	Retained Earnings Undistributed Earnings From Equity Method Investees RetainedEarningsUndistributedEarningsFromEquityMethodInvestees	26100000	USD
CY2019Q4	us-gaap	Retained Earnings Undistributed Earnings From Equity Method Investees RetainedEarningsUndistributedEarningsFromEquityMethodInvestees	25600000	USD
CY2020Q1	us-gaap	Equity Method Investment Other Than Temporary Impairment EquityMethodInvestmentOtherThanTemporaryImpairment	3600000	USD
CY2020Q1	ghc	Number Of Equity Method Investments Impaired NumberOfEquityMethodInvestmentsImpaired	2	Investment
CY2020Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	35700000	USD
CY2019Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Amount EquitySecuritiesWithoutReadilyDeterminableFairValueAmount	38500000	USD
CY2020	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	4200000	USD
CY2019	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	5100000	USD
CY2018	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	11700000	USD
CY2020	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	7300000	USD
CY2018	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	2700000	USD
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	21494000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable AllowanceForDoubtfulAccountsReceivable	14276000	USD
CY2020Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	519577000	USD
CY2019Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	595321000	USD
CY2020Q4	us-gaap	Other Receivables OtherReceivables	17579000	USD
CY2019Q4	us-gaap	Other Receivables OtherReceivables	28895000	USD
CY2020Q4	us-gaap	Accounts And Other Receivables Net Current AccountsAndOtherReceivablesNetCurrent	537156000	USD
CY2019Q4	us-gaap	Accounts And Other Receivables Net Current AccountsAndOtherReceivablesNetCurrent	624216000	USD
CY2020Q4	us-gaap	Accounts Payable And Other Accrued Liabilities Current AccountsPayableAndOtherAccruedLiabilitiesCurrent	384743000	USD
CY2019Q4	us-gaap	Accounts Payable And Other Accrued Liabilities Current AccountsPayableAndOtherAccruedLiabilitiesCurrent	366963000	USD
CY2020Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	135493000	USD
CY2019Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	140738000	USD
CY2020Q4	us-gaap	Bank Overdrafts BankOverdrafts	2100000	USD
CY2019Q4	us-gaap	Bank Overdrafts BankOverdrafts	500000	USD
CY2020Q4	us-gaap	Inventory Raw Materials Net Of Reserves InventoryRawMaterialsNetOfReserves	45382000	USD
CY2019Q4	us-gaap	Inventory Raw Materials Net Of Reserves InventoryRawMaterialsNetOfReserves	35119000	USD
CY2020Q4	us-gaap	Inventory Work In Process Net Of Reserves InventoryWorkInProcessNetOfReserves	10402000	USD
CY2019Q4	us-gaap	Inventory Work In Process Net Of Reserves InventoryWorkInProcessNetOfReserves	10775000	USD
CY2020Q4	us-gaap	Inventory Finished Goods Net Of Reserves InventoryFinishedGoodsNetOfReserves	64061000	USD
CY2019Q4	us-gaap	Inventory Finished Goods Net Of Reserves InventoryFinishedGoodsNetOfReserves	70602000	USD
CY2020Q4	us-gaap	Inventory For Long Term Contracts Or Programs InventoryForLongTermContractsOrPrograms	777000	USD
CY2019Q4	us-gaap	Inventory For Long Term Contracts Or Programs InventoryForLongTermContractsOrPrograms	4338000	USD
CY2020Q4	us-gaap	Inventory Net Of Allowances Customer Advances And Progress Billings InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings	120622000	USD
CY2019Q4	us-gaap	Inventory Net Of Allowances Customer Advances And Progress Billings InventoryNetOfAllowancesCustomerAdvancesAndProgressBillings	120834000	USD
CY2020Q4	us-gaap	Land Land	19394000	USD
CY2019Q4	us-gaap	Land Land	17489000	USD
CY2020Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	176653000	USD
CY2019Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	133189000	USD
CY2020Q4	us-gaap	Machinery And Equipment Gross MachineryAndEquipmentGross	398334000	USD
CY2019Q4	us-gaap	Machinery And Equipment Gross MachineryAndEquipmentGross	370218000	USD
CY2020Q4	us-gaap	Leasehold Improvements Gross LeaseholdImprovementsGross	229512000	USD
CY2019Q4	us-gaap	Leasehold Improvements Gross LeaseholdImprovementsGross	233842000	USD
CY2020Q4	us-gaap	Construction In Progress Gross ConstructionInProgressGross	25301000	USD
CY2019Q4	us-gaap	Construction In Progress Gross ConstructionInProgressGross	79963000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	849194000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	834701000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	470908000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	450031000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	378286000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	384670000	USD
CY2020	us-gaap	Depreciation Depreciation	74300000	USD
CY2019	us-gaap	Depreciation Depreciation	59300000	USD
CY2018	us-gaap	Depreciation Depreciation	56700000	USD
CY2019	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	2100000	USD
CY2018	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	800000	USD
CY2020	us-gaap	Tangible Asset Impairment Charges TangibleAssetImpairmentCharges	2300000	USD
CY2019	us-gaap	Tangible Asset Impairment Charges TangibleAssetImpairmentCharges	300000	USD
CY2018	us-gaap	Tangible Asset Impairment Charges TangibleAssetImpairmentCharges	200000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	56800000	USD
CY2020	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	6	segment
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	113669000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	104007000	USD
CY2020	ghc	Short Termand Monthto Month Lease Cost ShortTermandMonthtoMonthLeaseCost	21862000	USD
CY2019	ghc	Short Termand Monthto Month Lease Cost ShortTermandMonthtoMonthLeaseCost	19267000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	18718000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	20582000	USD
CY2020	us-gaap	Sublease Income SubleaseIncome	18508000	USD
CY2019	us-gaap	Sublease Income SubleaseIncome	20108000	USD
CY2020	ghc	Lease Cost Netof Sublease Income LeaseCostNetofSubleaseIncome	135741000	USD
CY2019	ghc	Lease Cost Netof Sublease Income LeaseCostNetofSubleaseIncome	123748000	USD
CY2020	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	11400000	USD
CY2019	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	1100000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	113664000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	112671000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	27031000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	236714000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	462560000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	526417000	USD
CY2020Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	86797000	USD
CY2019Q4	us-gaap	Operating Lease Liability Current OperatingLeaseLiabilityCurrent	92714000	USD
CY2020Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	428849000	USD
CY2019Q4	us-gaap	Operating Lease Liability Noncurrent OperatingLeaseLiabilityNoncurrent	477004000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	515646000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	569718000	USD
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P9Y10M24D
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y6M
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.044
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.043
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	106994000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	88721000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	71003000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	57310000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	45968000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	280837000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	650833000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	135187000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	515646000	USD
CY2020Q4	ghc	Lessee Operating Lease Lease Notyet Commenced Payments Due LesseeOperatingLeaseLeaseNotyetCommencedPaymentsDue	1900000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	53200000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	47400000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	52000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	46000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	38000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	28000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	21000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	20000000	USD
CY2018Q4	us-gaap	Goodwill Gross GoodwillGross	1644164000	USD
CY2018Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	346452000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	1297712000	USD
CY2019	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	84515000	USD
CY2019	us-gaap	Goodwill Written Off Related To Sale Of Business Unit GoodwillWrittenOffRelatedToSaleOfBusinessUnit	579000	USD
CY2019	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	6631000	USD
CY2019Q4	us-gaap	Goodwill Gross GoodwillGross	1734731000	USD
CY2019Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	346452000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	1388279000	USD
CY2020	us-gaap	Goodwill Purchase Accounting Adjustments GoodwillPurchaseAccountingAdjustments	154000	USD
CY2020	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	73950000	USD
CY2020	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	6878000	USD
CY2020	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	29245000	USD
CY2020Q4	us-gaap	Goodwill Gross GoodwillGross	1838080000	USD
CY2020Q4	us-gaap	Goodwill Impaired Accumulated Impairment Loss GoodwillImpairedAccumulatedImpairmentLoss	353330000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	1484750000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	481950000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	277304000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	204646000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	452952000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	219471000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	233481000	USD
CY2020Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	120437000	USD
CY2019	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-717000	USD
CY2019Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	140197000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	403295000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	390144000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	257312000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	3973000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	36335000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	66196000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	407268000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	426479000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	323508000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	77882000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	6669000	USD
CY2020	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	84551000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	8083000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	4954000	USD
CY2020	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	13037000	USD
CY2020	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	6958000	USD
CY2020	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	2754000	USD
CY2020	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	9712000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	92923000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	14377000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	107300000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	16500000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	63838000	USD
CY2019	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	80338000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	2949000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	6630000	USD
CY2019	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	9579000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	9400000	USD
CY2019	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	8683000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	28849000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	69751000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	98600000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	46059000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	16718000	USD
CY2018	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	62777000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	2240000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-23809000	USD
CY2018	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	-21569000	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	10924000	USD
CY2018	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	-32000	USD
CY2018	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	10892000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	59223000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-7123000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52100000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	85526000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	89561000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	67937000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	15366000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	-4064000	USD
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	-1279000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	2048000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	-1743000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount	-1731000	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	6982000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	2012000	USD
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	1618000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	107300000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	98600000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	52100000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	72787000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits	69013000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	3795000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	3545000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	53499000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	51608000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Domestic DeferredTaxAssetsOperatingLossCarryforwardsDomestic	18272000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Domestic DeferredTaxAssetsOperatingLossCarryforwardsDomestic	1765000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Foreign DeferredTaxAssetsOperatingLossCarryforwardsForeign	15802000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Foreign DeferredTaxAssetsOperatingLossCarryforwardsForeign	15214000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Deferred Rent DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDeferredRent	74240000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Deferred Rent DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDeferredRent	84923000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Other DeferredTaxAssetsTaxDeferredExpenseOther	6214000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Other DeferredTaxAssetsTaxDeferredExpenseOther	6003000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	250096000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	236678000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	47217000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	46243000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	202879000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	190435000	USD
CY2020Q4	ghc	Deferred Tax Liabilities Unrealized Gainson Availableforsale Securities DeferredTaxLiabilitiesUnrealizedGainsonAvailableforsaleSecurities	88371000	USD
CY2019Q4	ghc	Deferred Tax Liabilities Unrealized Gainson Availableforsale Securities DeferredTaxLiabilitiesUnrealizedGainsonAvailableforsaleSecurities	75709000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssets	90921000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssets	92233000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	15807000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	16303000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	61148000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	74407000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Undistributed Foreign Earnings DeferredTaxLiabilitiesUndistributedForeignEarnings	1866000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Undistributed Foreign Earnings DeferredTaxLiabilitiesUndistributedForeignEarnings	1670000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	715757000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	606178000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	512878000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	415743000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Undistributed Foreign Earnings DeferredTaxLiabilitiesUndistributedForeignEarnings	1900000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1572000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2483000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	17331000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	742000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	656000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	1072000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	500000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	12187000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	1072000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	1291000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	692000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	3161000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1898000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1572000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2483000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued	0	USD
CY2020Q4	us-gaap	Other Long Term Debt OtherLongTermDebt	3520000	USD
CY2019Q4	us-gaap	Other Long Term Debt OtherLongTermDebt	83000	USD
CY2020Q4	us-gaap	Debt Longterm And Shortterm Combined Amount DebtLongtermAndShorttermCombinedAmount	512555000	USD
CY2019Q4	us-gaap	Debt Longterm And Shortterm Combined Amount DebtLongtermAndShorttermCombinedAmount	512829000	USD
CY2020Q4	us-gaap	Debt Current DebtCurrent	6452000	USD
CY2019Q4	us-gaap	Debt Current DebtCurrent	82179000	USD
CY2020Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	506103000	USD
CY2019Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	430650000	USD
CY2020	ghc	Average Outstanding Debt Amount AverageOutstandingDebtAmount	512400000	USD
CY2019	ghc	Average Outstanding Debt Amount AverageOutstandingDebtAmount	500600000	USD
CY2019	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.051
CY2020	us-gaap	Debt Instrument Interest Rate During Period DebtInstrumentInterestRateDuringPeriod	0.051
CY2020	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-34400000	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-23600000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-32500000	USD
CY2020	us-gaap	Asset Impairment Charges AssetImpairmentCharges	30200000	USD
CY2019	us-gaap	Asset Impairment Charges AssetImpairmentCharges	9200000	USD
CY2018	us-gaap	Asset Impairment Charges AssetImpairmentCharges	8100000	USD
CY2020	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	4200000	USD
CY2019	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	5100000	USD
CY2018	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	11700000	USD
CY2020	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	7300000	USD
CY2018	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	2700000	USD
CY2020	us-gaap	Equity Method Investment Other Than Temporary Impairment EquityMethodInvestmentOtherThanTemporaryImpairment	3600000	USD
CY2020	ghc	Number Of Equity Method Investments Impaired NumberOfEquityMethodInvestmentsImpaired	2	Investment
CY2020Q4	us-gaap	Deferred Revenue DeferredRevenue	343322000	USD
CY2019Q4	us-gaap	Deferred Revenue DeferredRevenue	359048000	USD
CY2020	ghc	Deferred Revenue Period Increase Decrease Percentage DeferredRevenuePeriodIncreaseDecreasePercentage	-0.04
CY2020	us-gaap	Deferred Revenue Revenue Recognized1 DeferredRevenueRevenueRecognized1	309800000	USD
CY2019Q4	us-gaap	Capitalized Contract Cost Net CapitalizedContractCostNet	31020000	USD
CY2020	ghc	Contract Costs Capitalized Duringthe Period ContractCostsCapitalizedDuringthePeriod	51891000	USD
CY2020	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	-58855000	USD
CY2020	ghc	Changein Capitalized Contract Cost Other ChangeinCapitalizedContractCostOther	307000	USD
CY2020Q4	us-gaap	Capitalized Contract Cost Net CapitalizedContractCostNet	24363000	USD
CY2018Q4	us-gaap	Capitalized Contract Cost Net CapitalizedContractCostNet	21311000	USD
CY2019	ghc	Contract Costs Capitalized Duringthe Period ContractCostsCapitalizedDuringthePeriod	66607000	USD
CY2019	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	-57741000	USD
CY2019	ghc	Changein Capitalized Contract Cost Other ChangeinCapitalizedContractCostOther	843000	USD
CY2019Q4	us-gaap	Capitalized Contract Cost Net CapitalizedContractCostNet	31020000	USD
CY2017Q4	us-gaap	Capitalized Contract Cost Net CapitalizedContractCostNet	16043000	USD
CY2018	ghc	Contract Costs Capitalized Duringthe Period ContractCostsCapitalizedDuringthePeriod	55664000	USD
CY2018	us-gaap	Capitalized Contract Cost Amortization CapitalizedContractCostAmortization	-49284000	USD
CY2018	ghc	Changein Capitalized Contract Cost Other ChangeinCapitalizedContractCostOther	-1112000	USD
CY2018Q4	us-gaap	Capitalized Contract Cost Net CapitalizedContractCostNet	21311000	USD
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	29140	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	584.50
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	1100	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	420.65
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	1350	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	424.91
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	1650	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	610.14
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	27240	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	584.24
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	183189	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	569.31
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	85000	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	426.86
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	77258	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	325.26
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	190931	shares
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	29387000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	604.65
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	190931	shares
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P6Y7M6D
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	604.65
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	100804	shares
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P4Y
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	741.45
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1	P8Y
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0053
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.2770
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0145
CY2020	us-gaap	Net Income Loss NetIncomeLoss	300365000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	327855000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	271206000	USD
CY2020	ghc	Dividends Paid Common Stock And Sharebased Compensation Cash DividendsPaidCommonStockAndSharebasedCompensationCash	29970000	USD
CY2019	ghc	Dividends Paid Common Stock And Sharebased Compensation Cash DividendsPaidCommonStockAndSharebasedCompensationCash	29553000	USD
CY2018	ghc	Dividends Paid Common Stock And Sharebased Compensation Cash DividendsPaidCommonStockAndSharebasedCompensationCash	28617000	USD
CY2020	us-gaap	Undistributed Earnings UndistributedEarnings	270395000	USD
CY2019	us-gaap	Undistributed Earnings UndistributedEarnings	298302000	USD
CY2018	us-gaap	Undistributed Earnings UndistributedEarnings	242589000	USD
CY2020	ghc	Percentage Of Undistributed Earnings Allocated To Common Stockholders PercentageOfUndistributedEarningsAllocatedToCommonStockholders	0.9945
CY2019	ghc	Percentage Of Undistributed Earnings Allocated To Common Stockholders PercentageOfUndistributedEarningsAllocatedToCommonStockholders	0.9945
CY2018	ghc	Percentage Of Undistributed Earnings Allocated To Common Stockholders PercentageOfUndistributedEarningsAllocatedToCommonStockholders	0.9939
CY2020	ghc	Undistributed Earnings Allocated To Common Stockholders UndistributedEarningsAllocatedToCommonStockholders	268917000	USD
CY2019	ghc	Undistributed Earnings Allocated To Common Stockholders UndistributedEarningsAllocatedToCommonStockholders	296665000	USD
CY2018	ghc	Undistributed Earnings Allocated To Common Stockholders UndistributedEarningsAllocatedToCommonStockholders	241115000	USD
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	29812000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	28423000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	298729000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	326052000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	269538000	USD
CY2020	ghc	Additional Undistributed Earnings Due To Dilutive Stock Options AdditionalUndistributedEarningsDueToDilutiveStockOptions	4000	USD
CY2019	ghc	Additional Undistributed Earnings Due To Dilutive Stock Options AdditionalUndistributedEarningsDueToDilutiveStockOptions	13000	USD
CY2018	ghc	Additional Undistributed Earnings Due To Dilutive Stock Options AdditionalUndistributedEarningsDueToDilutiveStockOptions	10000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	298733000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	326065000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	269548000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5124000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5285000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5333000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	5139000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	5327000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	5370000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	58.30
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	61.70
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	50.55
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	58.13
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	61.21
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	50.20
CY2020	ghc	Antidilutive Restricted Stock AntidilutiveRestrictedStock	12000	shares
CY2019	ghc	Antidilutive Restricted Stock AntidilutiveRestrictedStock	12000	shares
CY2018	ghc	Antidilutive Restricted Stock AntidilutiveRestrictedStock	23000	shares
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	5.80
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	5.56
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	5.32
CY2019	ghc	Number Of Multiemployer Plans Contributed To NumberOfMultiemployerPlansContributedTo	1	multiemployer_plan
CY2018	ghc	Number Of Multiemployer Plans Contributed To NumberOfMultiemployerPlansContributedTo	1	multiemployer_plan
CY2020	ghc	Number Of Multiemployer Plans Contributed To NumberOfMultiemployerPlansContributedTo	1	multiemployer_plan
CY2019	us-gaap	Multiemployer Plan Employer Contribution Cost MultiemployerPlanEmployerContributionCost	100000	USD
CY2018	us-gaap	Multiemployer Plan Employer Contribution Cost MultiemployerPlanEmployerContributionCost	100000	USD
CY2020	us-gaap	Multiemployer Plan Employer Contribution Cost MultiemployerPlanEmployerContributionCost	100000	USD
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8800000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	9800000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	8600000	USD
CY2020	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	213302000	USD
CY2019	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	-564000	USD
CY2018	us-gaap	Gain Loss On Sale Of Business GainLossOnSaleOfBusiness	8157000	USD
CY2020	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	7327000	USD
CY2019	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	0	USD
CY2018	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	2697000	USD
CY2020	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	4209000	USD
CY2019	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	5080000	USD
CY2018	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	11663000	USD
CY2020	us-gaap	Business Combination Step Acquisition Equity Interest In Acquiree Remeasurement Gain BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain	3708000	USD
CY2019	us-gaap	Business Combination Step Acquisition Equity Interest In Acquiree Remeasurement Gain BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain	0	USD
CY2018	us-gaap	Business Combination Step Acquisition Equity Interest In Acquiree Remeasurement Gain BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain	0	USD
CY2020	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-2153000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-1070000	USD
CY2018	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-3844000	USD
CY2020	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	1370000	USD
CY2019	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	28994000	USD
CY2018	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	0	USD
CY2020	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	1039000	USD
CY2019	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	267000	USD
CY2018	us-gaap	Equity Securities Fv Ni Realized Gain EquitySecuritiesFvNiRealizedGain	2845000	USD
CY2020	ghc	Losson Guarantor Lease Obligations LossonGuarantorLeaseObligations	1014000	USD
CY2019	ghc	Losson Guarantor Lease Obligations LossonGuarantorLeaseObligations	1075000	USD
CY2018	ghc	Losson Guarantor Lease Obligations LossonGuarantorLeaseObligations	17518000	USD
CY2020	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	USD
CY2019	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-82000	USD
CY2018	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	2539000	USD
CY2020	us-gaap	Other Nonoperating Gains Losses OtherNonoperatingGainsLosses	1400000	USD
CY2019	us-gaap	Other Nonoperating Gains Losses OtherNonoperatingGainsLosses	881000	USD
CY2018	us-gaap	Other Nonoperating Gains Losses OtherNonoperatingGainsLosses	958000	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	214534000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	32431000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2103000	USD
CY2020Q1	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	2600000	USD
CY2020Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Impairment Loss Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount	4800000	USD
CY2020Q2	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	2600000	USD
CY2020Q3	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	1600000	USD
CY2019Q1	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	1300000	USD
CY2019Q3	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	3700000	USD
CY2018Q3	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	8500000	USD
CY2018Q4	us-gaap	Equity Securities Without Readily Determinable Fair Value Upward Price Adjustment Annual Amount EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount	3200000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	399354000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	99335000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	300019000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	133553000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	34087000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	99466000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-174347000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-37510000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-136837000	USD
CY2020Q4	us-gaap	Loss Contingency Pending Claims Number LossContingencyPendingClaimsNumber	0	claim
CY2020	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	6	segment
CY2020	us-gaap	Severance Costs1 SeveranceCosts1	6163000	USD
CY2020	ghc	Operating Lease Abandonment Cost OperatingLeaseAbandonmentCost	9942000	USD
CY2020	us-gaap	Restructuring Reserve Accelerated Depreciation RestructuringReserveAcceleratedDepreciation	3573000	USD
CY2020	us-gaap	Restructuring Charges RestructuringCharges	19678000	USD
CY2020	us-gaap	Operating Lease Impairment Loss OperatingLeaseImpairmentLoss	11448000	USD
CY2020	us-gaap	Tangible Asset Impairment Charges TangibleAssetImpairmentCharges	2321000	USD
CY2020	us-gaap	Defined Benefit Plan Cost Of Providing Special Or Contractual Termination Benefit Recognized During Period DefinedBenefitPlanCostOfProvidingSpecialOrContractualTerminationBenefitRecognizedDuringPeriod	13781000	USD
CY2020	us-gaap	Restructuring Settlement And Impairment Provisions RestructuringSettlementAndImpairmentProvisions	47228000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2889121000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2932099000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	2695966000	USD
CY2020	ghc	Operating Income Before Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long Lived Assets OperatingIncomeBeforeAmortizationOfIntangibleAssetsAndImpairmentOfGoodwillAndOtherLongLivedAssets	187357000	USD
CY2019	ghc	Operating Income Before Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long Lived Assets OperatingIncomeBeforeAmortizationOfIntangibleAssetsAndImpairmentOfGoodwillAndOtherLongLivedAssets	206941000	USD
CY2018	ghc	Operating Income Before Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long Lived Assets OperatingIncomeBeforeAmortizationOfIntangibleAssetsAndImpairmentOfGoodwillAndOtherLongLivedAssets	301684000	USD
CY2020	ghc	Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long Lived Assets AmortizationOfIntangibleAssetsAndImpairmentOfGoodwillAndOtherLongLivedAssets	86950000	USD
CY2019	ghc	Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long Lived Assets AmortizationOfIntangibleAssetsAndImpairmentOfGoodwillAndOtherLongLivedAssets	62395000	USD
CY2018	ghc	Amortization Of Intangible Assets And Impairment Of Goodwill And Other Long Lived Assets AmortizationOfIntangibleAssetsAndImpairmentOfGoodwillAndOtherLongLivedAssets	55523000	USD
CY2020	us-gaap	Operating Income Loss OperatingIncomeLoss	100407000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	144546000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	246161000	USD
CY2020	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	6664000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	11664000	USD
CY2018	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	14473000	USD
CY2020	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-34439000	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-23628000	USD
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-32549000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-11378000	USD
CY2020	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-59315000	USD
CY2019	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-162798000	USD
CY2018	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-120541000	USD
CY2020	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	60787000	USD
CY2019	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	98668000	USD
CY2018	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-15843000	USD
CY2020	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	214534000	USD
CY2019	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	32431000	USD
CY2018	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2103000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	407268000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	426479000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	323508000	USD
CY2020	us-gaap	Depreciation Depreciation	74257000	USD
CY2019	us-gaap	Depreciation Depreciation	59253000	USD
CY2018	us-gaap	Depreciation Depreciation	56722000	USD
CY2020	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	22656000	USD
CY2019	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	20422000	USD
CY2018	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	18221000	USD
CY2020	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	65874000	USD
CY2019	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	93947000	USD
CY2018	us-gaap	Property Plant And Equipment Additions PropertyPlantAndEquipmentAdditions	98067000	USD
CY2020Q4	ghc	Identifiable Assets IdentifiableAssets	4006935000	USD
CY2019Q4	ghc	Identifiable Assets IdentifiableAssets	3891557000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	573102000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	585080000	USD
CY2020Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	155777000	USD
CY2019Q4	us-gaap	Investments In Affiliates Subsidiaries Associates And Joint Ventures InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures	162249000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	1708305000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	1292350000	USD
CY2020Q4	us-gaap	Assets Assets	6444119000	USD
CY2019Q4	us-gaap	Assets Assets	5931236000	USD
CY2020Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	732257000	USD
CY2020Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	652871000	USD
CY2020Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	716982000	USD
CY2020Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	787011000	USD
CY2020Q1	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	177152000	USD
CY2020Q2	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	162840000	USD
CY2020Q3	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	166207000	USD
CY2020Q4	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	209202000	USD
CY2020Q1	us-gaap	Depreciation Depreciation	16704000	USD
CY2020Q2	us-gaap	Depreciation Depreciation	22913000	USD
CY2020Q3	us-gaap	Depreciation Depreciation	18481000	USD
CY2020Q4	us-gaap	Depreciation Depreciation	16159000	USD
CY2020Q1	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14165000	USD
CY2020Q2	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14327000	USD
CY2020Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14150000	USD
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	47.45
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5274000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5196000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5060000	shares
CY2020Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	4970000	shares
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-6.32
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.60
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	15.22
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	47.34
CY2020Q1	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5274000	shares
CY2020Q2	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5201000	shares
CY2020Q3	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5072000	shares
CY2019Q4	us-gaap	Depreciation Depreciation	16495000	USD
CY2019Q1	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	13060000	USD
CY2019Q2	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	12880000	USD
CY2019Q3	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	13572000	USD
CY2020Q4	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	2937000	USD
CY2020Q1	us-gaap	Investment Income Interest InvestmentIncomeInterest	1151000	USD
CY2020Q2	us-gaap	Investment Income Interest InvestmentIncomeInterest	954000	USD
CY2020Q3	us-gaap	Investment Income Interest InvestmentIncomeInterest	890000	USD
CY2020Q4	us-gaap	Investment Income Interest InvestmentIncomeInterest	876000	USD
CY2020Q1	us-gaap	Interest Expense InterestExpense	7678000	USD
CY2020Q2	us-gaap	Interest Expense InterestExpense	7377000	USD
CY2020Q3	us-gaap	Interest Expense InterestExpense	7247000	USD
CY2020Q4	us-gaap	Interest Expense InterestExpense	16008000	USD
CY2020Q1	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-18403000	USD
CY2020Q2	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-12136000	USD
CY2020Q3	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-10489000	USD
CY2020Q4	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-18287000	USD
CY2020Q1	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	-100393000	USD
CY2020Q2	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	39890000	USD
CY2020Q3	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	59364000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	61926000	USD
CY2020Q1	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	2688000	USD
CY2020Q2	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	8100000	USD
CY2020Q3	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	222000	USD
CY2020Q4	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	203524000	USD
CY2020Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-79291000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	60762000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	108054000	USD
CY2020Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	317743000	USD
CY2020Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-45400000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	41900000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	30000000	USD
CY2020Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	80800000	USD
CY2020Q1	us-gaap	Profit Loss ProfitLoss	-33891000	USD
CY2020Q2	us-gaap	Profit Loss ProfitLoss	18862000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	78054000	USD
CY2019Q4	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	13731000	USD
CY2019Q1	us-gaap	Asset Impairment Charges AssetImpairmentCharges	0	USD
CY2020Q4	us-gaap	Profit Loss ProfitLoss	236943000	USD
CY2020Q1	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	-646000	USD
CY2020Q2	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	8000	USD
CY2020Q3	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	439000	USD
CY2020Q4	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	-198000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	-33245000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	18854000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	77615000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	237141000	USD
CY2020Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-71188000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	35922000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	98878000	USD
CY2020Q4	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	536772000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-6.32
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.61
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	15.25
CY2020Q4	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	4982000	shares
CY2019Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	692199000	USD
CY2019Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	737602000	USD
CY2019Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	738820000	USD
CY2019Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	763478000	USD
CY2019Q1	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	174686000	USD
CY2019Q2	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	172297000	USD
CY2019Q3	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	178182000	USD
CY2019Q4	ghc	Selling Generaland Administrative Expenses SellingGeneralandAdministrativeExpenses	192494000	USD
CY2019Q1	us-gaap	Depreciation Depreciation	13523000	USD
CY2019Q2	us-gaap	Depreciation Depreciation	13884000	USD
CY2019Q3	us-gaap	Depreciation Depreciation	15351000	USD
CY2020Q4	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14138000	USD
CY2020Q1	us-gaap	Asset Impairment Charges AssetImpairmentCharges	16401000	USD
CY2020Q2	us-gaap	Asset Impairment Charges AssetImpairmentCharges	11511000	USD
CY2020Q3	us-gaap	Asset Impairment Charges AssetImpairmentCharges	1916000	USD
CY2020Q4	us-gaap	Asset Impairment Charges AssetImpairmentCharges	342000	USD
CY2020Q1	us-gaap	Costs And Expenses CostsAndExpenses	724172000	USD
CY2020Q2	us-gaap	Costs And Expenses CostsAndExpenses	646994000	USD
CY2020Q3	us-gaap	Costs And Expenses CostsAndExpenses	676738000	USD
CY2020Q4	us-gaap	Costs And Expenses CostsAndExpenses	740810000	USD
CY2020Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	8085000	USD
CY2020Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	5877000	USD
CY2020Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	40244000	USD
CY2020Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	46201000	USD
CY2020Q1	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-1547000	USD
CY2020Q2	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1182000	USD
CY2020Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	4092000	USD
CY2019Q2	us-gaap	Asset Impairment Charges AssetImpairmentCharges	693000	USD
CY2019Q3	us-gaap	Asset Impairment Charges AssetImpairmentCharges	372000	USD
CY2019Q4	us-gaap	Asset Impairment Charges AssetImpairmentCharges	8087000	USD
CY2019Q1	us-gaap	Costs And Expenses CostsAndExpenses	652196000	USD
CY2019Q2	us-gaap	Costs And Expenses CostsAndExpenses	679639000	USD
CY2019Q3	us-gaap	Costs And Expenses CostsAndExpenses	722552000	USD
CY2019Q4	us-gaap	Costs And Expenses CostsAndExpenses	733166000	USD
CY2019Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	40003000	USD
CY2019Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	57963000	USD
CY2019Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	16268000	USD
CY2019Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	30312000	USD
CY2019Q1	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1679000	USD
CY2019Q2	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1467000	USD
CY2019Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	4683000	USD
CY2019Q4	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	3835000	USD
CY2019Q1	us-gaap	Investment Income Interest InvestmentIncomeInterest	1700000	USD
CY2019Q2	us-gaap	Investment Income Interest InvestmentIncomeInterest	1579000	USD
CY2019Q3	us-gaap	Investment Income Interest InvestmentIncomeInterest	1474000	USD
CY2019Q4	us-gaap	Investment Income Interest InvestmentIncomeInterest	1398000	USD
CY2019Q1	us-gaap	Interest Expense InterestExpense	7425000	USD
CY2019Q2	us-gaap	Interest Expense InterestExpense	8386000	USD
CY2019Q3	us-gaap	Interest Expense InterestExpense	6776000	USD
CY2019Q4	us-gaap	Interest Expense InterestExpense	7192000	USD
CY2019Q1	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-19928000	USD
CY2019Q2	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-12253000	USD
CY2019Q3	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-19556000	USD
CY2019Q4	us-gaap	Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent	-111061000	USD
CY2019Q1	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	24066000	USD
CY2019Q2	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	7791000	USD
CY2019Q3	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	17404000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni Gain Loss EquitySecuritiesFvNiGainLoss	49407000	USD
CY2019Q1	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	29351000	USD
CY2019Q2	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	1228000	USD
CY2019Q3	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	5556000	USD
CY2019Q4	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	-3704000	USD
CY2019Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	109302000	USD
CY2019Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	73895000	USD
CY2019Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	58165000	USD
CY2019Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	185117000	USD
CY2019Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	27600000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16700000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	15200000	USD
CY2019Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	39100000	USD
CY2019Q1	us-gaap	Profit Loss ProfitLoss	81702000	USD
CY2019Q2	us-gaap	Profit Loss ProfitLoss	57195000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	42965000	USD
CY2019Q4	us-gaap	Profit Loss ProfitLoss	146017000	USD
CY2019Q1	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	-46000	USD
CY2019Q2	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	114000	USD
CY2019Q3	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	-180000	USD
CY2019Q4	ghc	Income Loss Attributableto Redeemable Noncontrolling Interestand Nonredeemable Noncontrolling Interest IncomeLossAttributabletoRedeemableNoncontrollingInterestandNonredeemableNoncontrollingInterest	136000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	81748000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	57081000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	43145000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	145881000	USD
CY2019Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	90038000	USD
CY2019Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	44986000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	25059000	USD
CY2019Q4	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	267238000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	15.38
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	10.74
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	8.12
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	27.45
CY2019Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5284000	shares
CY2019Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5285000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5285000	shares
CY2019Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	5284000	shares
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	15.26
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	10.65
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	8.05
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	27.25
CY2019Q1	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5326000	shares
CY2019Q2	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5329000	shares
CY2019Q3	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5329000	shares
CY2019Q4	ghc	Weighted Average Number Of Potentially Dilutive Shares Outstanding WeightedAverageNumberOfPotentiallyDilutiveSharesOutstanding	5324000	shares

Files In Submission

Name	View Source	Status
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0000104889-21-000018-index.html	Edgar Link	pending
0000104889-21-000018.txt	Edgar Link	pending
0000104889-21-000018-xbrl.zip	Edgar Link	pending
a2020q410-kex21.htm	Edgar Link	pending
a2020q410-kex23.htm	Edgar Link	pending
a2020q410-kex24.htm	Edgar Link	pending
a2020q410-kex311.htm	Edgar Link	pending
a2020q410-kex312.htm	Edgar Link	pending
a2020q410-kex32.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
ghc-20201231.htm	Edgar Link	pending
ghc-20201231.xsd	Edgar Link	pending
ghc-20201231_cal.xml	Edgar Link	unprocessable
ghc-20201231_def.xml	Edgar Link	unprocessable
ghc-20201231_g1.jpg	Edgar Link	pending
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$GHC
Graham Holdings Co Stock $ghc

2020 Q4 Form 10-K Financial Statement

#000010488921000018 Filed on February 24, 2021

Income Statement

Balance Sheet

Cashflow Statement

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$GHC Graham Holdings Co Stock $ghc

2020 Q4 Form 10-K Financial Statement

#000010488921000018 Filed on February 24, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$GHC
Graham Holdings Co Stock $ghc