Variable Interest Entities - Schedule of Payments Made to Entity Related to Guarantee Obligations (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	2 Months Ended	3 Months Ended
	Mar. 31, 2013	Feb. 28, 2013	Mar. 31, 2013	Mar. 31, 2012
Variable Interest Entity [Line Items]
Recoveries from Charged-Off Loans			$ (103)	$ (37)
2009 RSA [Member]
Variable Interest Entity [Line Items]
Regular Payments	0	0	306	229
Discharge Payments	0	0	0	0
Recoveries from Charged-Off Loans	0	0	(103)	(37)
Net guarantee obligation payments			$ 203	$ 192