Acquisitions (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Fair Value of Purchase Consideration [Abstract]      
Net cash outflow $ 0 $ 0  
Purchase Price Allocation [Abstract]      
Goodwill $ 196.0   $ 215.7