Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Operating Revenues	$ 674,766	$ 657,225	$ 2,006,879	$ 1,916,029
Operating Costs and Expenses [Abstract]
Operating	448,920	374,987	1,254,726	1,082,421
Selling, general and administrative	131,081	228,051	497,504	662,313
Depreciation of property, plant and equipment	13,648	16,002	41,909	46,525
Amortization of intangible assets	12,269	10,923	34,052	28,290
Impairment of goodwill and other long-lived assets	8,109	312	8,109	9,536
Total Operating Costs and Expenses	614,027	630,275	1,836,300	1,829,085
Income from Operations	60,739	26,950	170,579	86,944
Equity in earnings (losses) of affiliates, net	9,537	(532)	13,047	1,448
Interest income	611	861	3,884	3,397
Interest expense	(6,135)	(8,619)	(31,371)	(25,783)
Debt extinguishment costs	0	0	(11,378)	0
Non-operating pension and postretirement benefit income, net	22,214	17,621	66,641	55,042
Gain on marketable equity securities, net	44,962	0	28,306	0
Other income, net	3,142	1,963	14,662	6,881
Income Before Income Taxes	135,070	38,244	254,370	127,929
Provision for Income Taxes	10,000	13,400	39,700	40,000
Net Income	125,070	24,844	214,670	87,929
Net Income Attributable to Noncontrolling Interests	(6)	(60)	(149)	(63)
Net Income Attributable to Graham Holdings Company Common Stockholders	$ 125,064	$ 24,784	$ 214,521	$ 87,866
Per Share Information Attributable to Graham Holdings Company Common Stockholders
Basic net income per common share in dollars per share	$ 23.43	$ 4.45	$ 39.81	$ 15.74
Basic average number of common shares outstanding in shares	5,302	5,518	5,354	5,530
Diluted net income per common share in dollars per share	$ 23.28	$ 4.42	$ 39.54	$ 15.64
Diluted average number of common shares outstanding in shares	5,337	5,554	5,390	5,567