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Share-Based Compensation - Summary of Recent Share-Based Compensation Expense (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Share-based compensation expense $ 39.2 $ 34.2 $ 29.3
Tax benefit 15.1 13.2 $ 11.3
Cash received from stock options exercised 25.6 57.8  
Tax benefit realized from exercise of stock options 5.1 44.5  
Total compensation cost not yet recognized $ 66.4 $ 70.6  
Weighted average period for recognition (in years) 3 years