Organization, Basis of Presentation and Recent Accounting Pronouncements (Organization and Basis of Presentation) (Narrative) (Details)	Jun. 30, 2019 TelevisionStation
Television Broadcasting [Member]
Number of television broadcast stations	7

Number of television broadcast stations owned by the Company.

No definition available.

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Namespace Prefix:	ghc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant