Goodwill and Other Intangible Assets (Changes in Carrying Amount of Goodwill) (Details 1) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, beginning balance		$ 1,665,861	$ 1,481,489
Accumulated impairment losses, beginning balance		(366,151)	(358,535)
Goodwill, net, beginning balance		1,299,710	1,122,954
Acquisitions		41,840	143,149
Impairment			(7,616)
Dispositions		(11,191)	(412)
Foreign currency exchange rate changes		(32,647)	41,635
Goodwill, ending balance	$ 1,481,489	1,644,164	1,665,861
Accumulated impairment losses, ending balance	(358,535)	(346,452)	(366,151)
Goodwill, net, ending balance	1,122,954	1,297,712	1,299,710
Education [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		1,171,812	1,111,003
Accumulated impairment losses, beginning balance		(350,850)	(350,850)
Goodwill, net, beginning balance		820,962	760,153
Acquisitions		20,424	19,174
Impairment			0
Dispositions		(11,191)	0
Foreign currency exchange rate changes		(32,647)	41,635
Goodwill, ending balance	1,111,003	1,128,699	1,171,812
Accumulated impairment losses, ending balance	(350,850)	(331,151)	(350,850)
Goodwill, net, ending balance	760,153	797,548	820,962
Education [Member] | Kaplan International [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		615,861	555,185
Accumulated impairment losses, beginning balance		0	0
Goodwill, net, beginning balance		615,861	555,185
Acquisitions		62	19,174
Dispositions		0
Foreign currency exchange rate changes		(32,499)	41,502
Goodwill, ending balance	555,185	583,424	615,861
Accumulated impairment losses, ending balance	0	0	0
Goodwill, net, ending balance	555,185	583,424	615,861
Education [Member] | Higher Education [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		205,494	205,494
Accumulated impairment losses, beginning balance		(131,023)	(131,023)
Goodwill, net, beginning balance		74,471	74,471
Acquisitions		0	0
Dispositions		(11,191)
Foreign currency exchange rate changes		(40)	0
Goodwill, ending balance	205,494	174,564	205,494
Accumulated impairment losses, ending balance	(131,023)	(111,324)	(131,023)
Goodwill, net, ending balance	74,471	63,240	74,471
Education [Member] | Test Preparation [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		166,098	166,098
Accumulated impairment losses, beginning balance		(102,259)	(102,259)
Goodwill, net, beginning balance		63,839	63,839
Acquisitions		822	0
Dispositions		0
Foreign currency exchange rate changes		0	0
Goodwill, ending balance	166,098	166,920	166,098
Accumulated impairment losses, ending balance	(102,259)	(102,259)	(102,259)
Goodwill, net, ending balance	63,839	64,661	63,839
Education [Member] | Professional (U.S.) [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		184,359	184,226
Accumulated impairment losses, beginning balance		(117,568)	(117,568)
Goodwill, net, beginning balance		66,791	66,658
Acquisitions		19,540	0
Dispositions		0
Foreign currency exchange rate changes		(108)	133
Goodwill, ending balance	184,226	203,791	184,359
Accumulated impairment losses, ending balance	(117,568)	(117,568)	(117,568)
Goodwill, net, ending balance	66,658	86,223	66,791
Television Broadcasting [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		190,815	168,345
Accumulated impairment losses, beginning balance		0	0
Goodwill, net, beginning balance		190,815	168,345
Acquisitions		0	22,470
Impairment			0
Dispositions		0	0
Foreign currency exchange rate changes		0	0
Goodwill, ending balance	168,345	190,815	190,815
Accumulated impairment losses, ending balance	0	0	0
Goodwill, net, ending balance	168,345	190,815	190,815
Graham Healthcare Group [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		69,409	59,640
Accumulated impairment losses, beginning balance		0	0
Goodwill, net, beginning balance		69,409	59,640
Acquisitions		217	10,181
Impairment			0
Dispositions		0	(412)
Foreign currency exchange rate changes		0	0
Goodwill, ending balance	59,640	69,626	69,409
Accumulated impairment losses, ending balance	0	0	0
Goodwill, net, ending balance	59,640	69,626	69,409
Other Businesses [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance		233,825	142,501
Accumulated impairment losses, beginning balance		(15,301)	(7,685)
Goodwill, net, beginning balance		218,524	134,816
Acquisitions		21,199	91,324
Impairment	(1,600)		(7,616)
Dispositions		0	0
Foreign currency exchange rate changes		0	0
Goodwill, ending balance	142,501	255,024	233,825
Accumulated impairment losses, ending balance	(7,685)	(15,301)	(15,301)
Goodwill, net, ending balance	$ 134,816	$ 239,723	$ 218,524