Earnings Per Share (Reconciliation of Earnings (loss) to Earnings (loss) Attributable to Common Shares Used in Basic and Diluted (Loss) Earnings Per Share Calculation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Earnings (loss) from continuing operations	$ 55.1	$ 49.5	$ 92.6	$ (173.1)
(Earnings) allocated to participating vested share awards	(0.1)	(0.1)	(0.2)
Earnings (loss) from continuing operations attributable to common shares	$ 55.0	$ 49.4	$ 92.4	$ (173.1)