Net (Loss) Income per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic net (loss) income per common share:
Net (loss) income	$ (14.0)	$ 42.4
Weighted average common shares outstanding - Basic (in shares)	84.0	83.7
Basic net (loss) income per common share	$ (0.17)	$ 0.51
Diluted net (loss) income per common share:
Net (loss) income	$ (14.0)	$ 42.4
Weighted average common shares outstanding - Basic (in shares)	84.0	83.7
Plus incremental shares from assumed conversions:
Weighted average common shares outstanding - Dilutive (in shares)	84.0	84.3
Diluted net (loss) income per common share	$ (0.17)	$ 0.50
Restricted Stock Units
Plus incremental shares from assumed conversions:
Incremental shares from assumed conversions		0.3
Stock Options
Plus incremental shares from assumed conversions:
Incremental shares from assumed conversions		0.3