Earnings Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items]
Net income attributable to Graham Holdings Company common stockholders	$ 46,566	$ 41,996	$ 89,457	$ 63,082
Less: Dividends paid-common stock outstanding and unvested restricted shares	(6,948)	(7,080)	(21,587)	(21,282)
Undistributed earnings	$ 39,618	$ 34,916	$ 67,870	$ 41,800
Percent allocated to common stockholders	99.33%	99.06%	99.33%	99.06%
Undistributed Earnings Allocated To Common Stockholders	$ 39,352	$ 34,588	$ 67,416	$ 41,407
Add: Dividends paid-common stock outstanding	6,901	7,013	21,444	21,082
Numerator for basic earnings per share	46,253	41,601	88,860	62,489
Add: Additional undistributed earnings due to dilutive stock options	2	3	3	3
Numerator for diluted earnings per share	$ 46,255	$ 41,604	$ 88,863	$ 62,492
Weighted average shares outstanding (shares)	5,325	5,539	5,380	5,537
Denominator for diluted earnings per share (shares)	5,362	5,577	5,417	5,573
Graham Holdings Company Common Stockholders:
Basic income per common share in dollars per share	$ 8.69	$ 7.51	$ 16.52	$ 11.29
Diluted income per common share in dollars per share	$ 8.63	$ 7.46	$ 16.40	$ 11.21
Stock Option Plan [Member]
Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items]
Add: Effect of dilutive stock options (shares)	37	38	37	36