Assets Held for Sale - University of St. Augustine for Health Sciences, LLC (St. Augustine) (Details) - Disposal Group, Held-for-sale, Not Discontinued Operations	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) student	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Apr. 24, 2018 USD ($)
Business Acquisition [Line Items]
Revenues	$ 65,000,000	$ 57,000,000
St. Augustine
Business Acquisition [Line Items]
Revenues			$ 89,600,000
Operating loss			30,500,000
Depreciation			$ 4,100,000
Number of students within the institution (student) | student	3,200
St. Augustine | Subsequent Event
Business Acquisition [Line Items]
Consideration received from dispositions				$ 400,000,000