Organization, Basis of Presentation and Recent Accounting Pronouncements (Organization and Basis of Presentation) (Narrative) (Details)	3 Months Ended
Mar. 31, 2019 TelevisionStation
Percentage of ownership indicating control for consolidation purposes	more than 50%
Television Broadcasting [Member]
Number of television broadcast stations	7

Defines percentage of ownership required in the Company's domestic and foreign subsidiaries for consolidation of assets, liabilities, results of operations and cash flows of the Company.

No definition available.

Name:	ghc_PercentageOfOwnershipIndicatingControlForConsolidationPurposes
Namespace Prefix:	ghc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration