Stock-Based Compensation - Schedule of Other Stock Option Statistics (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Other disclosures
Total unrecognized compensation cost on nonvested options	$ 3.5
Non-qualified stock options
Other disclosures
Aggregate intrinsic value of outstanding options	51.7	$ 63.6
Aggregate intrinsic value of exercisable options	48.7	59.5
Total intrinsic value of options exercised	$ 26.0	$ 9.7
Total number of options exercisable (in shares)	1.8	2.3
Weighted average exercise price of options exercisable (in dollars per share)	$ 19.83	$ 16.16
Total unrecognized compensation cost on nonvested options	$ 1.2	$ 1.1