Private Education Loans - Schedule of Information Regarding Aggregate Changes in Accretable Yield (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
PEAKS Trust Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 34,984	$ 51,819
Accretion	(2,002)	(2,413)
Reclassification from nonaccretable difference and changes in expected cash flows	(1,330)	(1,508)
Balance at end of period	31,652	47,898
PEAKS Trust Student Loans [Member] | Analogy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	19,313	32,654
Accretion	(1,022)	(1,431)
Reclassification from nonaccretable difference and changes in expected cash flows	(933)	(2,541)
Balance at end of period	17,358	28,682
CUSO Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	12,793	11,728
Accretion	(722)	(668)
Reclassification from nonaccretable difference and changes in expected cash flows	(425)	60
Balance at end of period	11,646	11,120
CUSO Student Loans [Member] | Analogy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	7,611	5,857
Accretion	(432)	(346)
Reclassification from nonaccretable difference and changes in expected cash flows	(294)	266
Balance at end of period	$ 6,885	$ 5,777