Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (12.7)	$ 46.0	$ (20.5)	$ 19.3
Other comprehensive income (loss), net of income tax
Unrealized income on derivatives, net of income tax provision of $0.0, $0.0, $0.0 and $0.0, respectively	0.1	0.6	0.1	0.7
Employee pension and postretirement benefit expense, net of income tax benefit of $0.3, $0.0, $0.0 and $0.0, respectively	0.6	0.5	1.8	1.0
Foreign currency translation adjustments	8.6	1.2	(5.0)	(1.3)
Total other comprehensive income (loss), net of income tax	9.3	2.3	(3.1)	0.4
Comprehensive income (loss)	$ (3.4)	$ 48.3	$ (23.6)	$ 19.7