Income Taxes (Uncertain Tax Positions) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Interests and Penalties [Roll Forward]      
Balance at January 1 $ 28.9 $ 18.8 $ 0.6
Additions for tax positions related to prior years 9.0 26.5 10.3
Reductions for tax positions related to prior years (0.9) (13.9) 0
Additions based on tax positions related to the current year 3.8 0.4 7.9
Reductions due to lapse of the applicable statute of limitations (4.7) 0 0
Decrease related to settlements with taxing authorities (0.7) (2.9) 0
Balance at December 31 35.4 28.9 18.8
Accrued interest for uncertain tax positions $ 5.9 $ 4.7 $ 0.5