Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (3.1)	$ (7.8)
Other comprehensive income (loss), net of income tax:
Employee pension and postretirement benefit income (expense), net of income tax of $0.0 and $0.3, respectively	(0.6)	1.2
Foreign currency translation adjustments, net of income tax benefit (expense) of $3.2 and $(2.7), respectively	(10.0)	(13.6)
Total other comprehensive loss, net of income tax	(10.6)	(12.4)
Comprehensive loss	$ (13.7)	$ (20.2)