Share-based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated share-based compensation expense	$ 8.7
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	4.0	3.9
Number of options granted (in shares)	440,000
Weighted-average grant-date fair value per share of options granted (dollars per share)	$ 3.54
Number of options exercised (in shares)	0
Stock Options [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	1.0	0.9
Restricted Stock [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	1.9	1.7
Number of shares granted (in shares)	428,700
Weighted average grant date fair value, granted (dollars per share)	$ 6.72
Intrinsic value of shares vested/restrictions lapsed during the period	2.6
Restricted Stock Units Issued to Directors [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	0.3	0.2
Performance Share Awards [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 0.8	$ 1.1
Number of shares granted (in shares)	512,400
Weighted average grant date fair value, granted (dollars per share)	$ 6.40