Variable Interest Entities - Guarantee and Other Payments Related to PEAKS Program (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Variable Interest Entity [Line Items]
PEAKS Guarantee			$ 159,300
Payments on Behalf of Borrowers			$ 1,832
PEAKS Program [Member]
Variable Interest Entity [Line Items]
PEAKS Guarantee	$ 13,637	$ 40,713
Payments on Behalf of Borrowers	0	1,832
Total	$ 13,637	$ 42,545