Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	ghc
Entity Registrant Name	GRAHAM HOLDINGS CO
Entity Central Index Key	0000104889
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Public Float			$ 2,670
Class A Common Stock [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		964,001
Class B Common Stock [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		4,539,102