Derivative Instruments and Hedging Activities - Amount of Gain or Loss Recognized in Income on Derivatives (Detail) - Not Designated as Hedging Instruments - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain	$ 295	$ 132
Interest Rate Swap Contracts - Commercial Loans
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain	97	13
Interest Rate Lock Commitments - Mortgage Loans
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain	265	136
Forward Sale Contracts - Mortgage Loans
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain	$ (67)	$ (17)