Fair Value Disclosure (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Derivative assets	$ 11.8	$ 36.5
Trading securities	14.2	16.0
Total assets	26.0	52.5
Derivative liabilities	64.2	16.2
Total liabilities	64.2	16.2
Fair Value, Inputs, Level 1 [Member]
Trading securities	14.2	16.0
Total assets	14.2	16.0
Fair Value, Inputs, Level 2 [Member]
Derivative assets	11.8	36.5
Total assets	11.8	36.5
Derivative liabilities	64.2	16.2
Total liabilities	64.2	16.2
Fair Value, Inputs, Level 3 [Member]
Derivative assets
Trading securities
Total assets
Derivative liabilities
Total liabilities