Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits
Unrecognized Tax Benefits	$ 111.2	$ 87.2	$ 77.8
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	21.1	1.3
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	4.3	13.7
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	(0.9)	(5.6)
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	$ (0.5)	$ 0