Regulatory Update (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Regulatory Update [Abstract]
Guarantor support, total	$ 9.2	$ 21.6
Guarantor support, exception taken	9.0	18.0
Number of individual credit relationships incorporated into guarantor support analysis	25	25
Guarantor support, offset by cash payments received	3.3
Guarantor support, offset by increases in collateral values	3.8
Guarantor support, offset by charge-offs or additional reserves	5.3
Guarantor support, decline in value during the period	$ 12.4