Commitments and Contingencies - Aggregate Amount of Guarantee Payments, Discharge Payments and Payments on Behalf of Borrowers (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Schedule of Claims and Contingencies [Line Items]
PEAKS Guarantee					$ 159,300
Payments on Behalf of Borrowers					$ 1,832
Total	$ 14,924	$ 2,677	$ 33,550	$ 46,380
PEAKS Program [Member]
Schedule of Claims and Contingencies [Line Items]
PEAKS Guarantee	6,820	1,088	20,457	41,801
Payments on Behalf of Borrowers	0	0	0	1,832
CUSO RSA [Member]
Schedule of Claims and Contingencies [Line Items]
Regular Payments	1,560	1,589	3,840	2,747
Discharge Payments	$ 6,544	$ 0	$ 9,253	$ 0