Commitments and Contingencies (Other Contingencies) (Detail) $ in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Mar. 01, 2013 USD ($)	Dec. 31, 2012 a
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Gross Settlement And Defense Incurred Costs	$ 26.5	$ 14.8	$ 14.8		$ 88.8
Environmental Claims For A Site In Goodyear Arizona
Loss Contingencies [Line Items]
Estimated liability	30.9
Accrued environmental loss contingencies current	10.9
Other receivables	$ 6.0
Environmental Claims For Crab Orchard National Wildlife Refuge Superfund Site
Loss Contingencies [Line Items]
Approximate size of referenced site, acres | a							55,000
Ivo Peraica [Member] | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Paid Judgment Pursuant to Appeal				$ 2.7
Court Judgment						$ 10.6