Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Recorded share-based compensation expense	$ 7.7	$ 8.4	$ 24.0	$ 24.7
Total unrecognized compensation costs related to non-vested share-based compensation	$ 32.2		$ 32.2
Period for recognition			1 year 5 months 5 days
Common stock issued during period for exercise of stock options, restricted stock grants, and purchases under ESPP (shares)			2,953,389	948,773
Cash received from exercise of stock options and purchases through the ESPP			$ 59.8	$ 13.7