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) - Significant Unobservable Inputs (Level 3) - Residential mortgage-backed securities	9 Months Ended
	Sep. 30, 2016
Fair Value Assets Measured On Recurring Basis
Valuation technique to measure fair value	Discounted cash flow
Prepayment rate, Weighted Average of unobservable inputs	12.30%
Default rate, Weighted Average of unobservable inputs	9.10%
Loss severity, Weighted Average of unobservable inputs	60.60%
Minimum
Fair Value Assets Measured On Recurring Basis
Prepayment rate, Range of unobservable inputs	4.80%
Default rate, Range of unobservable inputs	3.80%
Loss severity, Range of unobservable inputs	45.30%
Maximum
Fair Value Assets Measured On Recurring Basis
Prepayment rate, Range of unobservable inputs	20.90%
Default rate, Range of unobservable inputs	27.00%
Loss severity, Range of unobservable inputs	66.70%