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) - Residential mortgage-backed securities [Member]	12 Months Ended
	Dec. 31, 2015
Fair Value Assets Measured On Recurring Basis [Line Items]
Valuation technique to measure fair value	Discounted cash flow
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Prepayment rate, Weighted Average of unobservable inputs	11.70%
Default rate, Weighted Average of unobservable inputs	8.50%
Loss severity, Weighted Average of unobservable inputs	58.50%
Significant Unobservable Inputs (Level 3) [Member] | Minimum [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Prepayment rate, Range of unobservable inputs	0.10%
Default rate, Range of unobservable inputs	3.70%
Loss severity, Range of unobservable inputs	41.40%
Significant Unobservable Inputs (Level 3) [Member] | Maximum [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Prepayment rate, Range of unobservable inputs	22.20%
Default rate, Range of unobservable inputs	20.60%
Loss severity, Range of unobservable inputs	64.60%