Share-Based Compensation (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Share-based compensation expense
Pre-tax compensation expense	$ 5.1	$ 4.6
Income tax benefit	(1.9)	(1.7)
Total share-based compensation expense, net of income taxes	3.2	2.9
Stock Option Awards
Share-based compensation expense
Pre-tax compensation expense	1.8	1.9
Income tax benefit	(0.7)	(0.7)
Total share-based compensation expense, net of income taxes	1.1	1.2
Restricted Stock Units, Restricted Stock Awards And Other Share Based Awards
Share-based compensation expense
Pre-tax compensation expense	3.3	2.7
Income tax benefit	(1.2)	(1.0)
Total share-based compensation expense, net of income taxes	$ 2.1	$ 1.7