Derivative Instruments and Hedging Activities - Income Statement Items for Derivatives not Designated as Hedging Instruments (Details 2) (Not designated as hedging instruments [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income for derivatives not designated as hedging instruments
Income for derivatives not designated as hedging instruments	$ (230)	$ 595
Net gain (loss) on mortgage banking activities [Member] | Interest rate locks with customers [Member]
Income for derivatives not designated as hedging instruments
Income for derivatives not designated as hedging instruments	(62)	222
Net gain (loss) on mortgage banking activities [Member] | Forward loan sale commitments [Member]
Income for derivatives not designated as hedging instruments
Income for derivatives not designated as hedging instruments	$ (168)	$ 373