Net (Loss) Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net (loss) income to common shareholders	$ (82.8)	$ 98.4	$ (30.6)	$ 141.8
Basic weighted average shares outstanding (in shares)	235.2	233.3	235.1	233.7
Diluted weighted average shares outstanding (in shares)	235.2	235.4	235.1	236.0
Net income (loss) per common share:
Basic net (loss) income per share (in dollars per share)	$ (0.35)	$ 0.42	$ (0.13)	$ 0.61
Diluted net (loss) income per share (in dollars per share)	$ (0.35)	$ 0.42	$ (0.13)	$ 0.60
Antidilutive securities excluded from computation of earnings per share (in shares)	4.6	3.0	4.5	2.9