Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivative financial instruments
Derivative assets	$ 6,222
Designated as hedging instruments [Member]
Derivative financial instruments
Derivative liabilities	2,234
Not designated as hedging instruments [Member]
Derivative financial instruments
Derivative assets	6,222	3,329
Derivative liabilities	5,159	2,490
Other Assets [Member] | Not designated as hedging instruments [Member] | Interest rate contracts [Member]
Derivative financial instruments
Derivative assets	3,360	2,132
Other Assets [Member] | Not designated as hedging instruments [Member] | Interest rate lock commitments [Member]
Derivative financial instruments
Derivative assets	2,862	1,197
Other Liabilities [Member] | Designated as hedging instruments [Member] | Interest rate swap [Member]
Derivative financial instruments
Derivative liabilities	2,234
Other Liabilities [Member] | Not designated as hedging instruments [Member] | Interest rate contracts [Member]
Derivative financial instruments
Derivative liabilities	3,340	2,063
Other Liabilities [Member] | Not designated as hedging instruments [Member] | Forward commitments [Member]
Derivative financial instruments
Derivative liabilities	$ 1,819	$ 427