Derivatives and Hedging Activities (Details) (Not Designated as Hedging Instrument [Member], Interest Rate Contracts [Member], USD $)	Mar. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Notional Amount of Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ 158,900,000	$ 177,000,000
Other Assets [Member]
Derivative [Line Items]
Fair value of asset derivative instruments	13,456,000	14,921,000
Other Liabilities [Member]
Derivative [Line Items]
Fair value of liability derivative instruments	$ 13,456,000	$ 14,921,000