Variable Interest Entities - Schedule of Revenue and Expenses of PEAKS Trust (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Variable Interest Entity [Line Items]
Student services and administrative expenses	$ 84,622	$ 100,440	$ 266,282	$ 297,225
Provision for private education loan losses	754	4,511	5,311	13,582
Interest expense	9,709	9,292	30,088	28,315
Income before provision for income taxes	2,825	14,139	21,761	14,995
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Revenue	2,036	2,727	6,695	9,099
Student services and administrative expenses	437	987	1,467	3,624
Provision for private education loan losses	(123)	4,511	5,295	13,582
Interest expense	2,760	8,722	8,845	26,195
Income before provision for income taxes	$ (1,038)	$ (11,493)	$ (8,912)	$ (34,302)