Private Education Loans - Schedule of Information Regarding Changes in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for loan losses	$ 3,313	$ 9,071	$ 4,557	$ 9,071
PEAKS Trust Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	39,596	29,349	42,353	29,349
Loans charged off	(7,898)	0	(11,959)	0
Recoveries from charged off loans	608	0	1,109	0
Provision for loan losses	4,615	9,071	5,418	9,071
Balance at end of period	36,921	$ 38,420	36,921	$ 38,420
CUSO Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	2,480		2,039
Loans charged off	0		0
Recoveries from charged off loans	0		0
Provision for loan losses	1,302		861
Balance at end of period	$ 1,178		$ 1,178