Derivatives Derivative Gains and Losses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ (54.4)	$ 0	$ (54.4)	$ 0
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax	(0.2)	(0.2)	(0.4)	(0.8)
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 0	$ 0	$ 0	$ (0.1)