Amount of lease cost, net of sublease income, recognized by lessee for lease contract

No definition available.

Name:	ghc_LeaseCostNetofSubleaseIncome
Namespace Prefix:	ghc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Payments due for operating lease arrangements which have not yet commenced as of the date of the balance sheet

+ References

No definition available.

+ Details

Name:	ghc_LesseeOperatingLeaseLeaseNotyetCommencedPaymentsDue
Namespace Prefix:	ghc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Term of lessee's option to renew or terminate an operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ghc_LesseeOperatingLeaseRenewalorTerminationOptionTerm
Namespace Prefix:	ghc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease not yet commenced, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractually required future rental payments receivable on noncancelable subleasing arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41502-112717

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueFutureMinimumSubleaseRentals
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ghc_TransactionAxis=ghc_SaleOfKHECampusesBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Leases (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Lease Cost Net of Sublease Income	$ 31,123	$ 90,454
Lessee, operating lease, lease not yet commenced, payments due	$ 3,900	$ 3,900
Future minimum sublease payments due			$ 66,000
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, operating lease, renewal or termination option term		1 year
Lessee, operating lease, lease not yet commenced, term of contract	1 year	1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, operating lease, renewal or termination option term		10 years
Lessee, operating lease, lease not yet commenced, term of contract	12 years	12 years
Sale of KHE Campuses business [Member]
Lessee, Lease, Description [Line Items]
Lease Cost Net of Sublease Income	$ (100)	$ 500