Commitments and Contingencies (Schedule Of Settlement And Defense Costs) (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($) claim	Jun. 30, 2019 USD ($) claim	Jun. 30, 2020 USD ($) claim	Jun. 30, 2019 USD ($) claim	Dec. 31, 2019 USD ($) claim	Dec. 31, 2018 USD ($) claim	Dec. 31, 2017 USD ($)	Mar. 31, 2020 claim	Mar. 31, 2019 claim	Aug. 21, 2012 USD ($)
Loss Contingencies [Line Items]
Pre-tax cash payments			$ 19,200,000	$ 17,900,000
Current asbestos liability	$ 65,000,000.0		$ 65,000,000.0		$ 65,000,000.0
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Estimated Percentage Of Insurance Which Covers Asbestos Costs					14.00%
Asbestos Cumulative Claims Resolved | claim	140,000		140,000
Loss Contingency, Pending Claims, Number | claim	28,927	28,851	28,927	28,851	29,056	29,089		29,162	28,498
Settlement / indemnity costs incurred (1)	$ 7,600,000	$ 8,600,000	$ 15,800,000	$ 30,000,000.0	$ 45,500,000
Defense costs incurred (1)	3,600,000	5,200,000	8,100,000	10,300,000	20,700,000
Gross Settlement And Defense Incurred Costs	11,200,000	13,800,000	23,900,000	40,300,000	66,200,000
Settlement / indemnity payments	5,900,000	6,800,000	16,900,000	15,600,000	38,900,000
Defense payments	4,200,000	6,200,000	8,500,000	10,200,000	21,400,000
Insurance receipts	2,700,000	4,800,000	6,200,000	7,900,000	18,800,000
Pre-tax cash payments	7,400,000	8,200,000	19,200,000	17,900,000	41,500,000
Cumulative Related Settlement Cost Incurred Before Insurance Recoveries	660,000,000		660,000,000
Cumulative Asbestos Settlement Cost Per Resolved Claim	4,700		4,700
Asbestos Settlement Cost Per Resolved Claim					15,800	$ 11,300	$ 7,800
Estimated Funds Available From Post Bankruptcy Trusts To Pay Current And Future Claimants	36,000,000,000		36,000,000,000
Court Judgment	23,900,000	$ 40,300,000	23,900,000	$ 40,300,000
Increase In Total Asbestos Liability					255,000,000
Insurance Receivable Asbestos	92,000,000		92,000,000		98,000,000
Asbestos Liability	686,000,000		686,000,000		$ 712,000,000
Percentage Of Asbestos Liability Attributable To Settlement And Defense Costs For Future Claims					85.00%
Current asbestos liability	65,000,000		65,000,000
Aggregate Value Of Policy Buy Out Agreements	$ 82,500,000		$ 82,500,000
Ronald Dummitt [Member] | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Court Judgment										$ 4,900,000