Variable Interest Entities - Schedule of Revenue and Expenses of PEAKS Trust (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Variable Interest Entity [Line Items]
Student services and administrative expenses	$ 90,252	$ 99,238
Provision for private education loan losses	1,244	0
Interest expense	10,388	11,812
Income (loss) before provision for income taxes	17,265	1,230
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Revenue	2,413	3,133
Student services and administrative expenses	541	1,416
Provision for private education loan losses	803	0
Interest expense	3,259	11,017
Income (loss) before provision for income taxes	$ (2,190)	$ (9,300)