Derivative Instruments and Hedging Activities - Derivatives Designated as Hedging Instruments (Detail) - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	$ 19,993	$ 19,269
Derivative Assets	0	0
Derivative Liabilities	254	438
Net loss	(299)	(377)	$ (66)
Gain (loss) recognized in other comprehensive income (loss)	(141)	(285)
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	18,566	19,269
Gain (loss) recognized in other comprehensive income (loss)	(141)	(285)
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net loss	308	377	66
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets	0	0
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liabilities	217	438
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	1,427
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Other Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net loss	9	$ 0	$ 0
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets	0
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Other Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liabilities	$ 37