Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 9.4	$ (375.8)	$ 65.5
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	58.4	(20.4)	(92.2)
Unrealized income (loss) on derivatives, net of income taxes of $0.0, $0.9 and $1.0, respectively	0.4	1.4	2.5
Employee pension and postretirement benefits, net of income taxes of $4.1, $(0.2) and $4.9, respectively	6.7	(4.1)	12.4
Total other comprehensive income (loss), net of tax	65.5	(23.1)	(77.3)
Comprehensive income (loss)	$ 74.9	$ (398.9)	$ (11.8)