Equity (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-Based Compensation
Share based compensation recognized	$ 4.3	$ 5.9
Unrecognized stock-based compensation expense	48.0
Estimated amortized share based compensation expense, remainder of 2014	16.9
Estimated amortized share based compensation expense, 2015	16.3
Estimated amortized share based compensation expense, 2016	7.6
Estimated amortized share based compensation expense, 2017	1.0
Unrecognized compensation expense not expected to vest	$ 6.2
Restricted stock units
Share-Based Compensation
Units granted during period (in shares)	0.3
Units vested in period (in shares)	0.2
Outstanding at the end of the period (in shares)	0.8
Performance stock units
Share-Based Compensation
Units granted during period (in shares)	0.2
Stock options
Share-Based Compensation
Stock options outstanding at the end of the period (in shares)	0.7
Options not yet exercisable, outstanding at the end of the period (in shares)	0.2