(Loss)/Earnings Per Share - EPS Calculation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net (loss)/income	$ (11.8)	$ (0.2)	$ (1.9)	$ 18.0	$ 15.5	$ 16.9	$ (13.9)	$ 50.4
Denominator:
Weighted average common shares outstanding - basic (in shares)	146.3			146.0			146.2	146.0
Weighted average common shares outstanding – diluted (in shares)	146.3			146.5			146.2	146.4
Basic earnings per common share:
Net (loss)/income per weighted average share - basic (in dollars per share)	$ (0.08)			$ 0.12			$ (0.10)	$ 0.35
Diluted earnings per common share:
Net (loss)/income per weighted average share - diluted (in dollars per share)	$ (0.08)			$ 0.12			$ (0.10)	$ 0.34
FMC Plan
Denominator:
Weighted average additional shares assuming conversion of potential common shares (in shares)	0.0			0.5			0.0	0.4