Earnings (Loss) Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Schedule of Earnings (Loss) Per Share, Basic and Diluted, Including Two Class Method [Line Items]
Net income (loss) attributable to Graham Holdings Company common stockholders	$ 112,450	$ (33,245)
Less: Dividends paid-common stock outstanding and unvested restricted shares	(15,106)	(15,289)
Undistributed earnings (loss)	$ 97,344	$ (48,534)
Percent allocated to common stockholders	99.33%	100.00%
Undistributed Earnings Allocated To Common Stockholders	$ 96,693	$ (48,534)
Add: Dividends paid-common stock outstanding	15,005	15,205
Numerator for basic earnings (loss) per share	111,698	(33,329)
Add: Additional undistributed earnings due to dilutive stock options	1	0
Numerator for diluted earnings (loss) per share	$ 111,699	$ (33,329)
Weighted average shares outstanding (shares)	4,967	5,274
Denominator for diluted earnings (loss) per share (shares)	4,977	5,274
Graham Holdings Company Common Stockholders:
Basic income (loss) per common share (in usd per share)	$ 22.49	$ (6.32)
Diluted income (loss) per common share (in usd per share)	$ 22.44	$ (6.32)
Stock Option Plan [Member]
Schedule of Earnings (Loss) Per Share, Basic and Diluted, Including Two Class Method [Line Items]
Add: Effect of dilutive stock options (shares)	10	0