Share-based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated share-based compensation expense	$ 9.0		$ 9.0
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	1.6	1.8	5.6	5.7
Number of options granted (in shares)			546,760
Weighted-average grant-date fair value per share of options granted (dollars per share)			$ 3.50
Number of options exercised (in shares)			0
Stock Options [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	0.3	0.2	1.3	1.1
Restricted Stock [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	0.4	0.5	2.3	2.2
Number of shares granted (in shares)			484,660
Weighted average grant date fair value, granted (dollars per share)			$ 6.66
Intrinsic value of shares vested/restrictions lapsed during the period			2.8
Restricted Stock Units Issued to Directors [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	0.2	0.2	0.5	0.4
Performance Share Awards [Member]
Share-based Compensation Expense [Abstract]
Share-based Compensation Expense	$ 0.7	$ 0.9	$ 1.5	$ 2.0
Number of shares granted (in shares)			512,400
Weighted average grant date fair value, granted (dollars per share)			$ 6.40