Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 112,635	$ (33,891)
Foreign currency translation adjustments:
Translation adjustments arising during the period	(486)	(37,376)
Pension and other postretirement plans:
Amortization of net prior service cost included in net income	792	671
Amortization of net actuarial (gain) loss included in net income	(2,429)	220
Total pension and other postretirement plans, before tax	(1,637)	891
Cash flow hedges gain (loss)	621	(1,578)
Other Comprehensive Loss, Before Tax	(1,502)	(38,063)
Income tax benefit related to items of other comprehensive loss	299	120
Other Comprehensive Loss, Net of Tax	(1,203)	(37,943)
Comprehensive Income (Loss)	111,432	(71,834)
Comprehensive (income) loss attributable to noncontrolling interests	(185)	646
Total Comprehensive Income (Loss) Attributable to Graham Holdings Company	$ 111,247	$ (71,188)