Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $)	0 Months Ended
	Oct. 24, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 23, 2008
Derivatives, Fair Value [Line Items]
Loans Receivable with Fixed Rates of Interest, Pool, Maturity Period	10 years
Loans Receivable with Fixed Rates of Interest	$ 29,100,000
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		19,945,000	0
Derivative Liabilities, Fair Value		241,000	0
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount				20,000,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	20,000,000
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value	25,000,000
Derivative, Fixed Interest Rate	2.10%			2.65%
Derivative, Collateral, Right to Reclaim Cash		300,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		19,945,000	0
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value		$ 241,000	$ 0