Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (67.1)	$ 9.4	$ (375.8)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(27.7)	58.4	(20.4)
Unrealized income (loss) on derivatives, net of income tax benefit of $0.0, $0.0 and $0.9, respectively	(0.4)	0.4	1.4
Employee pension and postretirement benefit costs, net of income tax expense (benefit) of $1.4, $4.2 and $(0.2), respectively	8.9	6.7	(4.1)
Total other comprehensive income (loss), net of tax	(19.2)	65.5	(23.1)
Comprehensive income (loss)	$ (86.3)	$ 74.9	$ (398.9)