Earnings Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items]
Net income attributable to Graham Holdings Company common stockholders	$ 77,615	$ 43,145	$ 63,224	$ 181,974
Less: Dividends paid-common stock outstanding and unvested restricted shares	(7,100)	(7,386)	(29,970)	(29,554)
Undistributed earnings	$ 70,515	$ 35,759	$ 33,254	$ 152,420
Percent allocated to common stockholders	99.43%	99.44%	99.43%	99.44%
Undistributed Earnings Allocated To Common Stockholders	$ 70,116	$ 35,559	$ 33,066	$ 151,570
Add: Dividends paid-common stock outstanding	7,059	7,345	29,806	29,389
Numerator for basic earnings per share	77,175	42,904	62,872	180,959
Add: Additional undistributed earnings due to dilutive stock options	1	2	1	7
Numerator for diluted earnings per share	$ 77,176	$ 42,906	$ 62,873	$ 180,966
Weighted average shares outstanding (shares)	5,060	5,285	5,176	5,285
Denominator for diluted earnings per share (shares)	5,072	5,329	5,192	5,328
Graham Holdings Company Common Stockholders:
Basic income per common share in dollars per share	$ 15.25	$ 8.12	$ 12.15	$ 34.24
Diluted income per common share in dollars per share	$ 15.22	$ 8.05	$ 12.11	$ 33.96
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)	12	44	16	43