Private Education Loans - Schedule of Information Regarding Changes in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for loan losses	$ (754)	$ (4,511)	$ (5,311)	$ (13,582)
PEAKS Trust Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	36,921	38,420	42,353	29,349
Loans charged off	(8,833)	0	(20,792)	0
Recoveries from charged off loans	570	0	1,679	0
Provision for loan losses	(123)	4,511	5,295	13,582
Balance at end of period	28,535	$ 42,931	28,535	$ 42,931
CUSO Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	1,178		2,039
Loans charged off	0		0
Recoveries from charged off loans	0		0
Provision for loan losses	877		16
Balance at end of period	$ 2,055		$ 2,055