Earnings Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Earnings Per Share, Basic and Diluted, Including Two Class Method [Line Items]
Net income attributable to Graham Holdings Company common stockholders	$ 39,586	$ 77,615	$ 267,394	$ 63,224
Less: Dividends paid-common stock outstanding and unvested restricted shares	(7,496)	(7,100)	(30,155)	(29,970)
Undistributed earnings	$ 32,090	$ 70,515	$ 237,239	$ 33,254
Percent allocated to common stockholders	99.32%	99.43%	99.32%	99.43%
Undistributed Earnings Allocated To Common Stockholders	$ 31,872	$ 70,116	$ 235,633	$ 33,066
Add: Dividends paid-common stock outstanding	7,447	7,059	29,953	29,806
Numerator for basic earnings per share	39,319	77,175	265,586	62,872
Add: Additional undistributed earnings due to dilutive stock options	1	1	5	1
Numerator for diluted earnings per share	$ 39,320	$ 77,176	$ 265,591	$ 62,873
Weighted average shares outstanding (shares)	4,961	5,060	4,966	5,176
Denominator for diluted earnings per share (shares)	4,977	5,072	4,980	5,192
Graham Holdings Company Common Stockholders:
Basic income per common share (in usd per share)	$ 7.93	$ 15.25	$ 53.49	$ 12.15
Diluted income per common share (in usd per share)	$ 7.90	$ 15.22	$ 53.33	$ 12.11
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)	16	12	14	16