Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 271,408	$ 302,489	$ 169,458
Foreign currency translation adjustments:
Translation adjustments arising during the year	(35,584)	33,175	(22,149)
Adjustment for sales of businesses with foreign operations	0	137	0
Total foreign currency translation adjustments	(35,584)	33,312	(22,149)
Unrealized gains on available-for-sale securities:
Unrealized gains for the year	0	112,086	55,507
Reclassification adjustment for realization of loss on sale of available-for-sale securities included in net income	0	0	1,879
Total unrealized gains on available-for-sale securities	0	112,086	57,386
Pension and other postretirement plans:
Actuarial (loss) gain	(101,013)	179,674	(133,915)
Prior service credit (cost)	4,262	(75)	0
Amortization of net actuarial (gain) loss included in net income	(11,349)	(6,527)	1,157
Amortization of net prior service (credit) cost included in net income	(947)	477	419
Curtailments and settlements included in net income	(30,267)	0	(17,993)
Total pension and other postretirement plans	(139,314)	173,549	(150,332)
Cash flow hedge gain (loss)	551	112	(334)
Other Comprehensive (Loss) Income, Before Tax	(174,347)	319,059	(115,429)
Income tax benefit (expense) related to items of other comprehensive (loss) income	37,510	(90,923)	37,235
Other Comprehensive (Loss) Income, Net of Tax	(136,837)	228,136	(78,194)
Comprehensive Income	134,571	530,625	91,264
Comprehensive income attributable to noncontrolling interests	(202)	(445)	(868)
Total Comprehensive Income Attributable to Graham Holdings Company	$ 134,369	$ 530,180	$ 90,396