Derivative Instruments and Hedging Activities - Amount of Gain or Loss Recognized in Income on Derivatives (Detail) - Not Designated as Hedging Instruments - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivative Gain (Loss)	$ 70	$ 36	$ (474)
Interest Rate Swap Contracts-Commercial Loans
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivative Gain (Loss)	(8)	(24)	(174)
Interest Rate Lock Commitments-Mortgage Loans
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivative Gain (Loss)	26	150	(382)
Forward Sale Contracts-Mortgage Loans
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivative Gain (Loss)	$ 52	$ (90)	$ 82