Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Unrealized income (loss) on derivatives, net of income taxes	$ 0.0	$ 0.9	$ 1.0
Employee pension and post retirement benefits, net of income taxes of	$ 4.1	$ (0.2)	$ 4.9