Derivatives and Hedging Activities (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2013 Contract	Mar. 31, 2012	Dec. 31, 2012 Contract
Credit risk
Derivatives and Hedging Activities (Textual) [Abstract]
Collateral pledged toward derivatives	$ 14,600,000
Fair value hedging of interest rate risk
Derivatives and Hedging Activities (Textual) [Abstract]
Number of derivative contracts outstanding	18	4
Derivative instruments outstanding	2
Recognized net gain related to ineffectiveness of the fair value hedging relationships	(86,000)	34,000
Net reduction of interest expense	12,000
Remaining number of derivative held	16
Derivatives and Hedging Activities (Additional Textual) [Abstract]
Aggregate notional amount designated as fair value hedges of interest rate risk	220,000,000	64,500,000
Aggregate notional amount designated as fair value hedges of interest rate risk on outstanding swap	21,000,000
Cash flow hedging
Derivatives and Hedging Activities (Textual) [Abstract]
Number of derivative contracts outstanding	5		5
Recognized net gain related to ineffectiveness of the fair value hedging relationships	1,000	81,000
Estimated additional amount of deferred gains reclassified to interest revenue	365,000
Increase to deposit interest expense	83,000
Derivatives and Hedging Activities (Additional Textual) [Abstract]
Total notional amount designated as cash flow hedges	400,000,000		400,000,000
Interest expense | Fair value hedging of interest rate risk
Derivatives and Hedging Activities (Textual) [Abstract]
Net reduction of interest expense	$ 1,060,000	$ 278,000