Fair Value - Significant Unobservable Inputs Used for Assets Measured at Fair Value on Non-Recurring Basis (Detail) (Fair value, non-recurring basis [Member], Real estate owned, net [Member])	6 Months Ended
	Jun. 30, 2013
Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	0.00%
Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	71.17%
Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss severity	10.25%