Income Taxes (Unrecognized Tax Benefits Reconciliation) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits at beginning of year	$ 47.1	$ 21.9	$ 20.9
Decreases in unrecognized tax benefits related to a prior year	0.2	0	0
Increases (decreases) in unrecognized tax benefits for the current year	2.4	25.2	1.0
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	(8.0)	0	0
Gross unrecognized tax benefits at end of year	57.3	47.1	21.9
Liability for unrecognized tax benefits	62.7	50.8
Unrecognized tax benefits that if recognized would impact effective tax rate	13.3	7.3
Unrecognized tax benefits that would impact deferred tax asset	49.4	43.5
Unrecognized tax benefits, interest recorded	1.7	0.6	0.6
Unrecognized tax benefits, interest accruals	4.1	2.4
Change in unrecognized tax benefits	$ 7.1