Goodwill and Other Intangible Assets (Other Intangible Assets) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Amortized Intangible Assets [Line Items]
Gross Carrying Amount	$ 481,950	$ 452,952
Accumulated Amortization	277,304	219,471
Net Carrying Amount	204,646	233,481
Indefinite-lived Intangible Assets [Line Items]
Net Carrying Amount	120,437	140,197
Student and Customer Relationships [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount	294,077	291,626
Accumulated Amortization	178,075	144,625
Net Carrying Amount	116,002	147,001
Trade Names and Trademarks [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount	109,809	87,190
Accumulated Amortization	54,766	42,770
Net Carrying Amount	$ 55,043	$ 44,420
Network affiliation agreements [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	10 years	10 years
Gross Carrying Amount	$ 17,400	$ 17,400
Accumulated Amortization	6,888	5,148
Net Carrying Amount	10,512	12,252
Databases and Technology [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount	34,864	30,623
Accumulated Amortization	19,924	12,850
Net Carrying Amount	14,940	17,773
Non-compete Agreements [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount	1,000	1,313
Accumulated Amortization	937	929
Net Carrying Amount	63	384
Other [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount	24,800	24,800
Accumulated Amortization	16,714	13,149
Net Carrying Amount	$ 8,086	$ 11,651
Minimum [Member] | Student and Customer Relationships [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	2 years	2 years
Minimum [Member] | Trade Names and Trademarks [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	2 years	2 years
Minimum [Member] | Databases and Technology [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	3 years	3 years
Minimum [Member] | Non-compete Agreements [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	2 years	2 years
Minimum [Member] | Other [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	1 year	1 year
Maximum [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	10 years
Maximum [Member] | Student and Customer Relationships [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	10 years	10 years
Maximum [Member] | Trade Names and Trademarks [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	10 years	10 years
Maximum [Member] | Databases and Technology [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	6 years	6 years
Maximum [Member] | Non-compete Agreements [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	5 years	5 years
Maximum [Member] | Other [Member]
Amortized Intangible Assets [Line Items]
Useful Life (in years)	8 years	8 years
Trade Names and Trademarks [Member]
Indefinite-lived Intangible Assets [Line Items]
Net Carrying Amount	$ 87,429	$ 100,491
Franchise Rights [Member]
Indefinite-lived Intangible Assets [Line Items]
Net Carrying Amount	21,858	28,556
FCC licenses [Member]
Indefinite-lived Intangible Assets [Line Items]
Net Carrying Amount	11,000	11,000
Licensure and Accreditation [Member]
Indefinite-lived Intangible Assets [Line Items]
Net Carrying Amount	$ 150	$ 150