Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Operating Revenues	$ 689,087	$ 674,766	$ 672,677	$ 659,436	$ 675,817	$ 657,225	$ 676,087	$ 582,717	$ 2,695,966	$ 2,591,846	$ 2,481,890
Operating Costs and Expenses
Operating	432,706	448,920	440,655	365,151	371,922	374,987	381,747	325,687	1,687,432	1,454,343	1,270,030
Selling, general and administrative	152,624	131,081	141,378	225,045	225,477	228,051	208,973	225,289	650,128	887,790	896,097
Depreciation of property, plant and equipment	14,813	13,648	13,619	14,642	15,984	16,002	15,871	14,652	56,722	62,509	64,620
Amortization of intangible assets	13,362	12,269	11,399	10,384	12,897	10,923	10,531	6,836	47,414	41,187	26,671
Impairment of goodwill and other long-lived assets	0	8,109	0	0	78	312	9,224	0	8,109	9,614	1,603
Total Operating Costs and Expenses	613,505	614,027	607,051	615,222	626,358	630,275	626,346	572,464	2,449,805	2,455,443	2,259,021
Income from Operations	75,582	60,739	65,626	44,214	49,459	26,950	49,741	10,253	246,161	136,403	222,869
Equity in earnings (losses) of affiliates, net	1,426	9,537	931	2,579	(4,697)	(532)	1,331	649	14,473	(3,249)	(7,937)
Interest income	1,469	611	1,901	1,372	3,184	861	1,173	1,363	5,353	6,581	3,093
Interest expense	(6,531)	(6,135)	(17,165)	(8,071)	(8,103)	(8,619)	(9,035)	(8,129)	(37,902)	(33,886)	(35,390)
Debt extinguishment costs	0	0	(11,378)	0					(11,378)	0	0
Non-operating pension and postretirement benefit income, net	53,900	22,214	23,041	21,386	17,657	17,621	18,620	18,801	120,541	72,699	80,665
Loss on marketable equity securities, net	(44,149)	44,962	(2,554)	(14,102)					(15,843)	0	0
Other income (expense), net	(12,559)	3,142	2,333	9,187	(2,640)	1,963	4,069	849	2,103	4,241	(12,642)
Income Before Income Taxes	69,138	135,070	62,735	56,565	54,860	38,244	65,899	23,786	323,508	182,789	250,658
Provision for (Benefit from) Income Taxes	12,400	10,000	16,100	13,600	(159,700)	13,400	23,900	2,700	52,100	(119,700)	81,200
Net Income	56,738	125,070	46,635	42,965	214,560	24,844	41,999	21,086	271,408	302,489	169,458
Net Income Attributable to Noncontrolling Interests	(53)	(6)	(69)	(74)	(382)	(60)	(3)	0	(202)	(445)	(868)
Net Income (Loss) Attributable to Parent	$ 56,685	$ 125,064	$ 46,566	$ 42,891	$ 214,178	$ 24,784	$ 41,996	$ 21,086	$ 271,206	$ 302,044	$ 168,590
Per Share Information Attributable to Graham Holdings Company Common Stockholders
Basic net income per common share (in usd per share)	$ 10.69	$ 23.43	$ 8.69	$ 7.84	$ 38.76	$ 4.45	$ 7.51	$ 3.77	$ 50.55	$ 54.24	$ 29.95
Basic average number of common shares outstanding (in shares)	5,270	5,302	5,325	5,436	5,473	5,518	5,539	5,535	5,333	5,516	5,559
Diluted net income per common share (in usd per share)	$ 10.61	$ 23.28	$ 8.63	$ 7.78	$ 38.52	$ 4.42	$ 7.46	$ 3.75	$ 50.20	$ 53.89	$ 29.80
Diluted average number of common shares outstanding (in shares)	5,309	5,337	5,362	5,473	5,509	5,554	5,577	5,569	5,370	5,552	5,589