Derivatives (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Counterparty default losses on forward contracts	$ 0	$ 0	$ 0
Commitments to originate loans held for sale	143.5
Notional amount of credit risk derivatives	194.3
Number of interest rate derivatives held	38
Termination value of derivatives in net liability position	6.6
Minimum collateral posting agreement amount	5.8
Forward Sales Commitments [Member]
Forward sales commitments	$ 182.7