Commitments and Contingencies (Schedule Of Settlement And Defense Costs) (Detail)	3 Months Ended			12 Months Ended
	Mar. 31, 2020 USD ($) claim	Dec. 31, 2019 USD ($) claim	Mar. 31, 2019 USD ($) claim	Dec. 31, 2019 USD ($) claim	Dec. 31, 2018 USD ($) claim	Dec. 31, 2017 USD ($)	Aug. 17, 2011 USD ($)
Loss Contingencies [Line Items]
Pre-tax cash payments	$ 11,700,000		$ 9,700,000
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%		14.00%
Asbestos Cumulative Claims Resolved | claim	139,000
Loss Contingency, Pending Claims, Number | claim	29,162	29,056	28,498	29,056	29,089
Settlement / indemnity costs incurred (1)	$ 8,200,000		$ 21,400,000	$ 45,500,000
Defense costs incurred (1)	4,400,000		5,100,000	20,700,000
Gross Settlement And Defense Incurred Costs	12,600,000		26,500,000	66,200,000
Settlement / indemnity payments	11,000,000.0		8,800,000	38,900,000
Defense payments	4,300,000		4,000,000.0	21,400,000
Insurance receipts	3,600,000		3,100,000	18,800,000
Pre-tax cash payments	11,700,000		9,700,000	41,500,000
Cumulative Related Settlement Cost Incurred Before Insurance Recoveries	650,000,000
Cumulative Asbestos Settlement Cost Per Resolved Claim	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
Court Judgment	12,600,000		$ 26,500,000
Increase In Total Asbestos Liability		$ 255,000,000
Insurance Receivable Asbestos	94,000,000	98,000,000		98,000,000
Asbestos Liability	696,000,000	$ 712,000,000		$ 712,000,000
Percentage Of Asbestos Liability Attributable To Settlement And Defense Costs For Future Claims		85.00%		85.00%
Current asbestos liability		$ 65,000,000		$ 65,000,000
Aggregate Value Of Policy Buy Out Agreements	$ 82,500,000
Ronald Dummitt [Member] | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Court Judgment							$ 4,900,000