Share-Based Compensation Share-based compensation expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Expense [Line Items]
Share-based Compensation	$ 5.8	$ 9.9	$ 13.5	$ 29.0
Stock Options [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	0.5	0.6	1.7	1.8
Restricted Share Awards [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	5.4	6.0	18.7	18.2
Performance Share Units [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	(0.1)	3.2	(6.9)	8.8
Restricted Share Units (RSUs) [Member]
Share-based Compensation Expense [Line Items]
Share-based Compensation	$ 0.0	$ 0.1	$ 0.0	$ 0.2