Fair Value Measurement of Assets and Liabilities - Schedule of Quantitative Information about Level 3 Inputs Used to Measure Fair Value of Available for Sale Securities (Detail) - Jun. 30, 2015 - Significant Unobservable Inputs (Level 3) - Residential mortgage-backed securities	Total
Fair Value Assets Measured On Recurring Basis
Valuation technique to measure fair value	Discounted cash flow
Prepayment rate, Weighted Average of unobservable inputs	11.90%
Default rate, Weighted Average of unobservable inputs	9.60%
Loss severity, Weighted Average of unobservable inputs	57.40%
Minimum
Fair Value Assets Measured On Recurring Basis
Prepayment rate, Range of unobservable inputs	4.50%
Default rate, Range of unobservable inputs	3.20%
Loss severity, Range of unobservable inputs	40.20%
Maximum
Fair Value Assets Measured On Recurring Basis
Prepayment rate, Range of unobservable inputs	18.90%
Default rate, Range of unobservable inputs	23.20%
Loss severity, Range of unobservable inputs	63.40%