Private Education Loans - Schedule of Information Regarding Aggregate Changes in Accretable Yield (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
PEAKS Trust Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 40,202	$ 59,929	$ 51,819	$ 70,580
Accretion	(2,036)	(2,727)	(6,695)	(9,099)
Reclassification from nonaccretable difference and changes in expected cash flows	(691)	(2,077)	(7,649)	(6,356)
Balance at end of period	37,475	55,125	37,475	55,125
PEAKS Trust Student Loans [Member] | Analogy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	24,233	36,444	32,654	42,274
Accretion	(1,157)	(1,602)	(3,864)	(5,302)
Reclassification from nonaccretable difference and changes in expected cash flows	(605)	(830)	(6,319)	(2,960)
Balance at end of period	22,471	$ 34,012	22,471	$ 34,012
CUSO Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	13,766		11,728
Accretion	(782)		(2,152)
Reclassification from nonaccretable difference and changes in expected cash flows	282		3,690
Balance at end of period	13,266		13,266
CUSO Student Loans [Member] | Analogy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	8,215		5,857
Accretion	(470)		(1,210)
Reclassification from nonaccretable difference and changes in expected cash flows	(71)		3,027
Balance at end of period	$ 7,674		$ 7,674