Commitments and Contingencies (Schedule Of Settlement And Defense Costs) (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018 USD ($) Claim	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Claim	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2018	Mar. 31, 2017
Loss Contingencies [Line Items]
Document Period End Date			Sep. 30, 2018
Pre-tax cash payments			$ 46,400,000	$ 46,800,000
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Asbestos Cumulative Claims Resolved | Claim	135,000		135,000
Loss Contingency, Pending Claims, Number	29,323	32,075	29,323	32,075	32,234	36,052		29,920	31,980
Settlement / indemnity costs incurred (1)	$ 7,600,000	$ 21,000,000	$ 49,600,000	$ 46,800,000	$ 51,800,000
Defense costs incurred (1)	6,200,000	9,700,000	20,100,000	28,700,000	36,500,000
Gross Settlement And Defense Incurred Costs	13,800,000	30,700,000	69,700,000	75,500,000	88,300,000
Settlement / indemnity payments	12,000,000	13,900,000	46,000,000	37,300,000	51,700,000
Defense payments	5,900,000	9,500,000	17,700,000	28,700,000	38,900,000
Insurance receipts	(6,300,000)	(4,800,000)	(17,300,000)	(19,200,000)	(28,100,000)
Pre-tax cash payments	11,600,000	$ 18,600,000	46,400,000	$ 46,800,000	62,500,000
Cumulative Related Settlement Cost Incurred Before Insurance Recoveries	580,000,000		580,000,000
Cumulative Asbestos Settlement Cost Per Resolved Claim	$ 4,300		$ 4,300
Asbestos Settlement Cost Per Resolved Claim					$ 7,800	$ 3,900	$ 3,100