Commitments and Contingencies (Schedule Of Settlement And Defense Costs) (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($) Claim	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Claim	Jun. 30, 2017 USD ($)	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			Jun. 30, 2018
Pre-tax cash payments			$ 34,900,000	$ 28,200,000
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Asbestos Cumulative Claims Resolved | Claim	134,000		134,000
Loss Contingency, Pending Claims, Number	29,920	31,980	29,920	31,980	32,234	36,052		30,990	35,560
Settlement / indemnity costs incurred (1)	$ 33,800,000	$ 7,300,000	$ 42,000,000	$ 25,800,000	$ 51,800,000
Defense costs incurred (1)	7,300,000	9,500,000	13,900,000	19,000,000	36,500,000
Gross Settlement And Defense Incurred Costs	41,100,000	16,800,000	55,900,000	44,800,000	88,300,000
Settlement / indemnity payments	29,600,000	9,300,000	34,100,000	23,400,000	51,700,000
Defense payments	6,700,000	11,300,000	11,800,000	19,200,000	38,900,000
Insurance receipts	(4,300,000)	(7,100,000)	(11,000,000)	(14,400,000)	(28,100,000)
Pre-tax cash payments	32,000,000	$ 13,500,000	34,900,000	$ 28,200,000	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