Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net Income	$ 78,054	$ 42,965	$ 63,025	$ 181,862
Foreign currency translation adjustments:
Translation adjustments arising during the period	20,430	(16,684)	(541)	(17,755)
Pension and other postretirement plans:
Amortization of net prior service cost (credit) included in net income	671	(932)	2,010	(3,210)
Amortization of net actuarial loss (gain) included in net income	304	(511)	914	(1,534)
Total pension and other postretirement plans, before tax	975	(1,443)	2,924	(4,744)
Cash flow hedges gain (loss)	157	(477)	(1,564)	(904)
Other Comprehensive Income (Loss), Before Tax	21,562	(18,604)	819	(23,403)
Income tax (expense) benefit related to items of other comprehensive income (loss)	(299)	518	(431)	1,512
Other Comprehensive Income (Loss), Net of Tax	21,263	(18,086)	388	(21,891)
Comprehensive Income	99,317	24,879	63,413	159,971
Comprehensive (income) loss attributable to noncontrolling interests	(439)	180	199	112
Total Comprehensive Income Attributable to Graham Holdings Company	$ 98,878	$ 25,059	$ 63,612	$ 160,083