Acquisitions and Dispositions of Businesses (Significant Component) (Details 3) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2015
Acqusitions and Dispositions [Abstract]
Disposal Group, Not Discontinued Operation, Revenue	$ 43,121	$ 167,244
Disposal Group, Not Discontinued Operation, Operating Income (Loss)	$ 629	$ (6,672)

Amount of operating income (loss) attributable to disposal group. Excludes discontinued operations.

No definition available.

Name:	ghc_DisposalGroupNotDiscontinuedOperationOperatingIncomeLoss
Namespace Prefix:	ghc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration