Private Education Loans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 Pool_Loan	Dec. 31, 2013	Feb. 28, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	$ 0	$ 0
PEAKS Trust Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of separate pools of loans	24
CUSO Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of separate pools of loans	48
Private Education Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, carrying amount	90,876,000
Loans, outstanding amount	184,710,000