(Loss)/Earnings Per Share - EPS Calculation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net (loss)/income	$ (0.2)	$ (1.9)	$ 15.5	$ 16.9	$ (2.1)	$ 32.4
Denominator:
Weighted average common shares outstanding - basic (in shares)	146.2		146.0		146.1	146.0
Weighted average common shares outstanding – diluted (in shares)	146.2		146.5		146.1	146.5
Basic earnings per common share:
Net (loss)/income per weighted average share - basic (in dollars per share)	$ 0		$ 0.11		$ (0.01)	$ 0.22
Diluted earnings per common share:
Net (loss)/income per weighted average share - diluted (in dollars per share)	$ 0		$ 0.11		$ (0.01)	$ 0.22
FMC Plan
Denominator:
Weighted average additional shares assuming conversion of potential common shares (in shares)	0.0		0.5		0.0	0.5