Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 8,250	$ 9,183	$ 10,298
Charged to cost and expenses	672	184	(245)
Write-offs (recoveries) of doubtful accounts	309	1,117	870
Balance at end of period	8,613	8,250	9,183
Student Loan [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	21,026	15,682	8,622
Charged to cost and expenses	17,858	15,917	19,019
Write-offs (recoveries) of doubtful accounts	19,523	10,573	11,959
Balance at end of period	$ 19,361	$ 21,026	$ 15,682