Derivative Instruments and Hedging Activities - Amount of Gain or Loss Recognized in Income on Derivatives (Detail) (Not Designated as Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	$ 132	$ (29)
Interest Rate Swap Contracts-Commercial Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	13	(8)
Interest Rate Lock Commitments - Mortgage Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	136	8
Forward Sale Contracts-Mortgage Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	$ (17)	$ (29)