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Derivative Financial Instruments and Hedging Activities - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) derivative	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) derivative	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Derivatives, Fair Value [Line Items]
Lower threshold requiring collateral to be posted, liabilities	$ 100,000		$ 100,000
Higher threshold requiring collateral to be posted, liabilities	250,000.00		250,000.00
Fair value hedge
Derivatives, Fair Value [Line Items]
Net hedge ineffectiveness, derivatives	70,000	$ 15,000	58,000	$ 173,000
Designated as hedging instrument | Fair value hedge
Derivatives, Fair Value [Line Items]
Accrued interest on swaps	$ 36,000		$ 36,000		$ 41,000
Interest rate swap | Designated as hedging instrument | Fair value hedge
Derivatives, Fair Value [Line Items]
Number of derivative instruments qualifying for short-cut hedge treatment | derivative	1		1
Number of derivative instruments | derivative	8		8
Interest rate swap | Designated as hedging instrument | Fair value hedge | Other assets
Derivatives, Fair Value [Line Items]
Interest rate contracts notional amount, Asset derivatives	$ 4,499,000		$ 4,499,000		4,589,000
Interest rate swap | Designated as hedging instrument | Fair value hedge | Other liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts notional amount, Liability derivatives	26,000,000		26,000,000		26,899,000
Interest income | Fair value hedge
Derivatives, Fair Value [Line Items]
Increase (decrease) in value of designated interest rate swaps recognized in interest income	966,000	(423,000)	420,000	313,000
Payment on interest rate swaps recorded in interest income	(233,000)	(252,000)	(469,000)	(505,000)
(Decrease) increase in value of hedged loans recognized in interest income	(1,023,000)	453,000	(451,000)	(78,000)
Decrease in value of yield maintenance agreement recognized against interest income	(13,000)	(15,000)	(27,000)	(62,000)
Net loss on derivatives recognized against interest income	(303,000)	$ (237,000)	(527,000)	$ (332,000)
Assets and liabilities at fair value measured on a recurring basis | Interest rate contract | Designated as hedging instrument | Fair value hedge | Other assets
Derivatives, Fair Value [Line Items]
Interest rate contracts fair value, Asset derivatives	116,000		116,000		61,000
Assets and liabilities at fair value measured on a recurring basis | Interest rate contract | Designated as hedging instrument | Fair value hedge | Other liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts fair value, Liability derivatives	$ 1,631,000		$ 1,631,000		$ 1,996,000

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