Contingencies - Aggregate Amount of Guarantee Payments, Discharge Payments and Payments on Behalf of Borrowers (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		2 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		2 Months Ended	4 Months Ended	6 Months Ended		2 Months Ended	4 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Feb. 28, 2013 PEAKS Program [Member]	Jun. 30, 2013 PEAKS Program [Member]	Jun. 30, 2013 PEAKS Program [Member]	Jun. 30, 2012 PEAKS Program [Member]	Jun. 30, 2013 2009 RSA [Member]	Jun. 30, 2012 2009 RSA [Member]	Jun. 30, 2013 2009 RSA [Member]	Jun. 30, 2012 2009 RSA [Member]	Feb. 28, 2013 Risk Share Agreement [Member] PEAKS Program [Member]	Jun. 30, 2013 Risk Share Agreement [Member] PEAKS Program [Member]	Jun. 30, 2013 Risk Share Agreement [Member] PEAKS Program [Member]	Jun. 30, 2012 Risk Share Agreement [Member] PEAKS Program [Member]	Feb. 28, 2013 Risk Share Agreement [Member] 2009 RSA [Member]	Jun. 30, 2013 Risk Share Agreement [Member] 2009 RSA [Member]	Jun. 30, 2013 Risk Share Agreement [Member] 2009 RSA [Member]	Jun. 30, 2012 Risk Share Agreement [Member] 2009 RSA [Member]
Schedule of Claims and Contingencies [Line Items]
PEAKS Guarantee					$ 854	$ 1,239	$ 385	$ 258					$ 854	$ 385	$ 1,239	$ 258
Regular Payments									77	439	383	668					0	0	383	668
Discharge Payments									0	0	0	0					0	0	0	0
Payments on Behalf of Borrowers	3,290	0	5,145	0	532	5,145	4,613	0					532	4,613	5,145	0
Recoveries from Charged-Off Loans	0	(50)	(103)	(87)					0	(50)	(103)	(87)					0	0	(103)	(87)
Total					$ 1,386	$ 6,384	$ 4,998	$ 258					$ 1,386	$ 4,998	$ 6,664	$ 839