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		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income for derivatives not designated as hedging instruments
Income for derivatives not designated as hedging instruments	$ 777	$ 691	$ 1,614	$ 223
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	1,394	1,060	2,341	829
Net gain (loss) on mortgage banking activities [Member] | Forward loan commitments [Member]
Income for derivatives not designated as hedging instruments
Income for derivatives not designated as hedging instruments	$ (617)	$ (369)	$ (727)	$ (606)