Fair Value Measurement of Assets and Liabilities - Schedule of Quantitative Information About Level 3 Inputs Used to Measure the Fair Value of Available For Sale Securities (Detail) (Significant Unobservable Inputs (Level 3) [Member])	6 Months Ended
	Jun. 30, 2013
Residential mortgage-backed securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Prepayment rate, Weighted Average of unobservable inputs	19.30%
Default rate, Weighted Average of unobservable inputs	7.00%
Loss severity, Weighted Average of unobservable inputs	51.40%
Trust preferred securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Loss severity, Weighted Average of unobservable inputs	20.30%
Market credit spreads, Weighted Average of unobservable inputs	5.20%
Discount rate, Weighted Average of unobservable inputs	6.70%
Minimum [Member] | Residential mortgage-backed securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Prepayment rate, Range of unobservable inputs	14.70%
Default rate, Range of unobservable inputs	4.30%
Loss severity, Range of unobservable inputs	40.20%
Minimum [Member] | Trust preferred securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Loss severity, Range of unobservable inputs	0.00%
Market credit spreads, Range of unobservable inputs	4.80%
Discount rate, Range of unobservable inputs	5.10%
Maximum [Member] | Residential mortgage-backed securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Prepayment rate, Range of unobservable inputs	25.20%
Default rate, Range of unobservable inputs	12.20%
Loss severity, Range of unobservable inputs	59.80%
Maximum [Member] | Trust preferred securities [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Loss severity, Range of unobservable inputs	100.00%
Market credit spreads, Range of unobservable inputs	5.40%
Discount rate, Range of unobservable inputs	7.90%