Summary of Quarterly Operating Results and Comprehensive Income (Loss) (Unaudited) (Quarterly Results) (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Operating Revenues	$ 763,478	$ 738,820	$ 737,602	$ 692,199	$ 689,087	$ 674,766	$ 672,677	$ 659,436	$ 2,932,099	$ 2,695,966	$ 2,591,846
Operating Costs and Expenses
Operating	524,277	517,935	503,763	477,230	432,706	448,920	440,655	365,151	2,023,205	1,687,432	1,454,343
Selling, general and administrative	170,576	175,322	148,419	148,383	152,624	131,081	141,378	225,045	642,700	650,128	887,790
Depreciation of property, plant and equipment	16,495	15,351	13,884	13,523	14,813	13,648	13,619	14,642	59,253	56,722	62,509
Amortization of intangible assets	13,731	13,572	12,880	13,060	13,362	12,269	11,399	10,384	53,243	47,414	41,187
Impairment of Long-Lived Assets	8,087	372	693	0	0	8,109	0	0	9,152	8,109	9,614
Total Operating Costs and Expenses	733,166	722,552	679,639	652,196	613,505	614,027	607,051	615,222	2,787,553	2,449,805	2,455,443
Income from Operations	30,312	16,268	57,963	40,003	75,582	60,739	65,626	44,214	144,546	246,161	136,403
Equity in earnings of affiliates, net	3,835	4,683	1,467	1,679	1,426	9,537	931	2,579	11,664	14,473	(3,249)
Interest income	1,398	1,474	1,579	1,700	1,469	611	1,901	1,372	6,151	5,353	6,581
Interest expense	(7,192)	(6,776)	(8,386)	(7,425)	(6,531)	(6,135)	(17,165)	(8,071)	(29,779)	(37,902)	(33,886)
Debt extinguishment costs					0	0	(11,378)	0	0	(11,378)	0
Non-operating pension and postretirement benefit income, net	111,061	19,556	12,253	19,928	53,900	22,214	23,041	21,386	162,798	120,541	72,699
(Loss) gain on marketable equity securities, net	49,407	17,404	7,791	24,066	(44,149)	44,962	(2,554)	(14,102)	98,668	(15,843)	0
Other income (expense), net	(3,704)	5,556	1,228	29,351	(12,559)	3,142	2,333	9,187	32,431	2,103	4,241
Income Before Income Taxes	185,117	58,165	73,895	109,302	69,138	135,070	62,735	56,565	426,479	323,508	182,789
Provision for Income Taxes	39,100	15,200	16,700	27,600	12,400	10,000	16,100	13,600	98,600	52,100	(119,700)
Net Income	146,017	42,965	57,195	81,702	56,738	125,070	46,635	42,965	327,879	271,408	302,489
Net Loss (Income) Attributable to Noncontrolling Interests	(136)	180	(114)	46	(53)	(6)	(69)	(74)	(24)	(202)	(445)
Net Income Attributable to Graham Holdings Company Common Stockholders	145,881	43,145	57,081	81,748	56,685	125,064	46,566	42,891	327,855	271,206	302,044
Quarterly Comprehensive Income (Loss)	$ 267,238	$ 25,059	$ 44,986	$ 90,038	$ (52,541)	$ 119,862	$ 13,345	$ 53,703	$ 427,321	$ 134,369	$ 530,180
Per Share Information Attributable to Graham Holdings Company Common Stockholders
Basic net income per common share (in usd per share)	$ 27.45	$ 8.12	$ 10.74	$ 15.38	$ 10.69	$ 23.43	$ 8.69	$ 7.84	$ 61.70	$ 50.55	$ 54.24
Basic average number of common shares outstanding (in shares)	5,284	5,285	5,285	5,284	5,270	5,302	5,325	5,436	5,285	5,333	5,516
Diluted net income per common share (in usd per share)	$ 27.25	$ 8.05	$ 10.65	$ 15.26	$ 10.61	$ 23.28	$ 8.63	$ 7.78	$ 61.21	$ 50.20	$ 53.89
Diluted average number of common shares outstanding (in shares)	5,324	5,329	5,329	5,326	5,309	5,337	5,362	5,473	5,327	5,370	5,552