Goodwill and Other Intangible Assets (Changes in Carrying Amount of Goodwill) (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 1,734,731	$ 1,644,164
Accumulated impairment losses, beginning balance	(346,452)	(346,452)
Goodwill, net, beginning balance	1,388,279	1,297,712
Measurement period adjustment	154
Acquisitions	73,950	84,515
Impairment	(6,878)
Dispositions		(579)
Foreign currency exchange rate changes	29,245	6,631
Goodwill, ending balance	1,838,080	1,734,731
Accumulated impairment losses, ending balance	(353,330)	(346,452)
Goodwill, net, ending balance	1,484,750	1,388,279
Education [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	1,140,958	1,128,699
Accumulated impairment losses, beginning balance	(331,151)	(331,151)
Goodwill, net, beginning balance	809,807	797,548
Measurement period adjustment	154
Acquisitions	13,022	6,207
Impairment	0
Dispositions		(579)
Foreign currency exchange rate changes	29,245	6,631
Goodwill, ending balance	1,183,379	1,140,958
Accumulated impairment losses, ending balance	(331,151)	(331,151)
Goodwill, net, ending balance	852,228	809,807
Education [Member] | Kaplan International [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	595,604	583,424
Accumulated impairment losses, beginning balance	0	0
Goodwill, net, beginning balance	595,604	583,424
Measurement period adjustment	154
Acquisitions	9,788	6,207
Dispositions		(579)
Foreign currency exchange rate changes	29,203	6,552
Goodwill, ending balance	634,749	595,604
Accumulated impairment losses, ending balance	0	0
Goodwill, net, ending balance	634,749	595,604
Education [Member] | Higher Education [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	174,564	174,564
Accumulated impairment losses, beginning balance	(111,324)	(111,324)
Goodwill, net, beginning balance	63,240	63,240
Measurement period adjustment	0
Acquisitions	0	0
Dispositions		0
Foreign currency exchange rate changes	0	0
Goodwill, ending balance	174,564	174,564
Accumulated impairment losses, ending balance	(111,324)	(111,324)
Goodwill, net, ending balance	63,240	63,240
Education [Member] | Supplemental Education [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	370,790	370,711
Accumulated impairment losses, beginning balance	(219,827)	(219,827)
Goodwill, net, beginning balance	150,963	150,884
Measurement period adjustment	0
Acquisitions	3,234	0
Dispositions		0
Foreign currency exchange rate changes	42	79
Goodwill, ending balance	374,066	370,790
Accumulated impairment losses, ending balance	(219,827)	(219,827)
Goodwill, net, ending balance	154,239	150,963
Television Broadcasting [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	190,815	190,815
Accumulated impairment losses, beginning balance	0	0
Goodwill, net, beginning balance	190,815	190,815
Measurement period adjustment	0
Acquisitions	0	0
Impairment	0
Dispositions		0
Foreign currency exchange rate changes	0	0
Goodwill, ending balance	190,815	190,815
Accumulated impairment losses, ending balance	0	0
Goodwill, net, ending balance	190,815	190,815
Manufacturing [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	234,993	231,479
Accumulated impairment losses, beginning balance	(7,616)	(7,616)
Goodwill, net, beginning balance	227,377	223,863
Measurement period adjustment	0
Acquisitions	0	3,514
Impairment	0
Dispositions		0
Foreign currency exchange rate changes	0	0
Goodwill, ending balance	234,993	234,993
Accumulated impairment losses, ending balance	(7,616)	(7,616)
Goodwill, net, ending balance	227,377	227,377
Graham Healthcare Group [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	98,421	69,626
Accumulated impairment losses, beginning balance	0	0
Goodwill, net, beginning balance	98,421	69,626
Measurement period adjustment	0
Acquisitions	0	28,795
Impairment	0
Dispositions		0
Foreign currency exchange rate changes	0	0
Goodwill, ending balance	98,421	98,421
Accumulated impairment losses, ending balance	0	0
Goodwill, net, ending balance	98,421	98,421
Other Businesses [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	69,544	23,545
Accumulated impairment losses, beginning balance	(7,685)	(7,685)
Goodwill, net, beginning balance	61,859	15,860
Measurement period adjustment	0
Acquisitions	60,928	45,999
Impairment	(6,878)
Dispositions		0
Foreign currency exchange rate changes	0	0
Goodwill, ending balance	130,472	69,544
Accumulated impairment losses, ending balance	(14,563)	(7,685)
Goodwill, net, ending balance	$ 115,909	$ 61,859