Derivative Instruments and Hedging Activities - Derivatives Not Designated as Hedging Instruments (Detail) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 73,995	$ 57,544
Derivative Assets, Fair Value	1,089	788
Derivative Liabilities, Fair Value	102	112
Income for derivatives not designated as hedging instruments	311	330	$ (1,147)
Interest Rate Locks with Customers [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	34,450	27,007
Interest Rate Locks with Customers [Member] | Net (Gain) Loss on Mortgage Banking Activities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Income for derivatives not designated as hedging instruments	301	467	(1,226)
Interest Rate Locks with Customers [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets, Fair Value	1,089	788
Interest Rate Locks with Customers [Member] | Other Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liabilities, Fair Value	0	0
Forward Loan Sale Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	39,545	30,537
Forward Loan Sale Commitments [Member] | Net (Gain) Loss on Mortgage Banking Activities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Income for derivatives not designated as hedging instruments	10	(137)	$ 79
Forward Loan Sale Commitments [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets, Fair Value	0	0
Forward Loan Sale Commitments [Member] | Other Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liabilities, Fair Value	$ 102	$ 112