Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 116,469
Instruction and educational support	63,776	$ 61,416
Provision for income taxes	2,150	7,887
Net income	9,467	$ 10,578
Tuition receivable - net	24,997		$ 23,122
Other current assets	10,558		11,293
Income taxes payable	2,541		1,038
Accounts payable and accrued expenses	45,806		46,177
Retained earnings	$ 168,413		162,006
Percentage of tuition revenue in total revenue	96.00%
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of new accounting standards			$ (171)
Accounting Standards Update 2014-09 | Balances without Adoption of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 116,338
Instruction and educational support	63,584
Provision for income taxes	2,167
Net income	9,511
Tuition receivable - net	23,769
Other current assets	12,084
Income taxes payable	2,624
Retained earnings	168,628
Accounting Standards Update 2014-09 | Effect of Change Higher/Lower
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	131
Instruction and educational support	192
Provision for income taxes	(17)
Net income	(44)
Tuition receivable - net	1,228
Other current assets	(1,526)
Income taxes payable	(83)
Retained earnings	(215)
Tuition
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	112,000
Academic fees
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	3,100
Textbook-related sales
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	900
Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 500