Goodwill and Other Intangible Assets - Summary of Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Subject to amortization:
Accumulated Amortization	$ (145,129)	$ (132,012)
Total	35,927	46,700
Not subject to amortization:
Tradenames	1,295,614	1,307,633
Gross Carrying Amount, Total	1,476,670	1,486,345
Net Carrying Amount, Total	1,331,541	1,354,333
Tradenames
Not subject to amortization:
Tradenames	1,295,614	1,307,633
Student rosters
Subject to amortization:
Gross Carrying Amount	98,266	96,712
Accumulated Amortization	(96,558)	(92,567)
Total	$ 1,708	$ 4,145
Not subject to amortization:
Weighted Average Amortization Period (Yrs)	1 year 9 months 22 days	2 years 8 months 15 days
Other
Subject to amortization:
Gross Carrying Amount	$ 82,790	$ 82,000
Accumulated Amortization	(48,571)	(39,445)
Total	$ 34,219	$ 42,555
Not subject to amortization:
Weighted Average Amortization Period (Yrs)	11 years 4 months 26 days	11 years 9 months 22 days