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Organization and Nature of Operations (Narrative) (Details)
Dec. 31, 2014
Category
Feb. 12, 2015
campus
Education [Member]    
Product Information [Line Items]    
Number of education business categories 3ghc_NumberOfEducationBusinessCategories
/ us-gaap_StatementBusinessSegmentsAxis
= ghc_EducationMember		  
Television Broadcasting [Member]    
Product Information [Line Items]    
Number of television broadcast stations owned 5ghc_NumberOfTelevisionBroadcastStationsOwned
/ us-gaap_StatementBusinessSegmentsAxis
= ghc_TelevisionBroadcastingMember		  
Number of major national networks each station is affiliated with 1ghc_NumberOfMajorNationalNetworksAffiliationWith
/ us-gaap_StatementBusinessSegmentsAxis
= ghc_TelevisionBroadcastingMember		  
Subsequent Event [Member] | Higher Education [Member]    
Product Information [Line Items]    
Number of nationally accredited ground campuses   38ghc_NumberOfNationallyAccreditedGroundCampuses
/ us-gaap_StatementBusinessSegmentsAxis
= ghc_HigherEducationMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember