Commitments and Contingencies (Schedule Of Activity Related To Asbestos Claim) (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 ($)	Apr. 22, 2016 USD ($)	Jul. 02, 2015 USD ($)	Sep. 17, 2013 USD ($)	Feb. 25, 2013	Feb. 23, 2011 USD ($)	Mar. 23, 2010 USD ($)
Loss Contingencies [Line Items]
Current asbestos liability	$ 65,000,000.0		$ 65,000,000.0		$ 65,000,000.0
Payments for asbestos-related fees and costs, net of insurance recoveries			19,200,000	$ 17,900,000
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Asbestos Settlement Cost Per Resolved Claim					$ 15,800	$ 11,300	$ 7,800
Current asbestos liability	65,000,000		65,000,000
Aggregate Value Of Policy Buy Out Agreements	82,500,000		82,500,000
Court Judgment	$ 23,900,000	$ 40,300,000	$ 23,900,000	$ 40,300,000
Beginning claims | claim	29,162	28,498	29,056	29,089	29,089
New claims | claim	577	769	1,258	1,444	2,848
Settlements | claim	(264)	(178)	(429)	(586)	(983)
Dismissals | claim	(548)	(238)	(958)	(1,096)	(1,898)
Ending claims | claim	28,927	28,851	28,927	28,851	29,056	29,089
Gross Settlement And Defense Incurred Costs	$ 11,200,000	$ 13,800,000	$ 23,900,000	$ 40,300,000	$ 66,200,000
Payments for asbestos-related fees and costs, net of insurance recoveries	$ 7,400,000	$ 8,200,000	$ 19,200,000	$ 17,900,000	$ 41,500,000
New York | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Ending claims | claim	18,000		18,000
Texas | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Ending claims | claim	100		100
Mississippi | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Ending claims | claim	300		300
OHIO | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Ending claims | claim	200		200
James Nelson | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Jury Verdict													$ 14,500,000
Court Judgment Against All Parties Held Responsible												$ 4,000,000.0
Additional Judgment Interest												$ 10,000.00
Share Of Responsibility Of Verdict													9.09%
Thomas Amato | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Share Of Responsibility Of Verdict											10.00%
Frank Vincinguerra | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Share Of Responsibility Of Verdict											20.00%
Richard DeLisle | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Jury Verdict										$ 8,000,000
Court Judgment										$ 1,300,000
Share Of Responsibility Of Verdict										16.00%
James Poage | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Court Judgment									$ 10,800,000
compensatory_damages									1,500,000
Additional Damages									$ 10,000,000
George Coulbourn | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Court Judgment								$ 6,800,000
Share Of Responsibility Of Verdict								20.00%
Jury Verdict Total								$ 9,000,000
Additional Damages								$ 5,000,000