Variable Interest Entities - Schedule of Revenue and Expenses of PEAKS Trust (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Variable Interest Entity [Line Items]
Student services and administrative expenses	$ 91,408	$ 97,547	$ 181,660	$ 196,785
Provision for private education loan losses	3,313	9,071	4,557	9,071
Interest expense	9,991	6,263	20,379	13,164
Income before provision for income taxes	1,671	574	18,936	6,715
PEAKS Trust [Member]
Variable Interest Entity [Line Items]
Revenue	2,246	3,239	4,659	6,372
Student services and administrative expenses	489	1,221	1,030	2,637
Provision for private education loan losses	4,615	9,071	5,418	9,071
Interest expense	2,826	5,508	6,085	11,614
Income before provision for income taxes	$ (5,684)	$ (12,561)	$ (7,874)	$ (16,950)