Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 24,844	$ 33,126	$ 87,929	$ 132,540
Foreign currency translation adjustments:
Translation adjustments arising during the period	11,470	(353)	34,776	(1,629)
Unrealized gains on available-for-sale securities:
Unrealized gains for the period, net	47,836	12,154	71,370	7,190
Reclassification of realized gain on sale of available-for-sale securities included in net income	0	0	0	(6,256)
Total unrealized gains on available-for-sale securities, before tax	47,836	12,154	71,370	934
Pension and other postretirement plans:
Amortization of net prior service cost included in net income	118	105	358	314
Amortization of net actuarial (gain) loss included in net income	(1,567)	289	(4,958)	868
Total pension and other postretirement plans, before tax	(1,449)	394	(4,600)	1,182
Cash flow hedge (loss) gain	(72)	49	(215)	49
Other Comprehensive Income, Before Tax	57,785	12,244	101,331	536
Income tax expense related to items of other comprehensive income	(18,540)	(5,039)	(26,665)	(866)
Other Comprehensive Income (Loss), Net of Tax	39,245	7,205	74,666	(330)
Comprehensive Income	64,089	40,331	162,595	132,210
Comprehensive income attributable to noncontrolling interests	(60)	0	(63)	(868)
Total Comprehensive Income Attributable to Graham Holdings Company	$ 64,029	$ 40,331	$ 162,532	$ 131,342