Condensed Consolidated Statements of Comprehensive Income (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 48.0	$ 5.3	$ 74.6	$ 33.4
Other comprehensive (loss) income, net of tax:
Translation adjustments	0.4	2.2	(2.3)	4.6
Adjustment for net periodic pension and other postretirement benefits plan cost	0.4	0.3	1.4	1.0
Other comprehensive income (loss), net of tax	0.8	2.5	(0.9)	5.6
Comprehensive income	$ 48.8	$ 7.8	$ 73.7	$ 39.0