Commitments and Contingencies (Schedule Of Activity Related To Asbestos Claim) (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($) claim	Jun. 30, 2020 USD ($) claim	Jun. 30, 2021 USD ($) claim	Jun. 30, 2020 USD ($) claim	Dec. 31, 2020 USD ($) claim	Dec. 31, 2019 USD ($) claim	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Current asbestos liability	$ 66,500,000		$ 66,500,000		$ 66,500,000
Payments for asbestos-related fees and costs, net of insurance recoveries			20,200,000	$ 19,200,000
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Asbestos Settlement Cost Per Resolved Claim			13,900			$ 15,800	$ 11,300
Current asbestos liability	66,500,000		66,500,000		$ 66,500,000
Aggregate Value Of Policy Buy Out Agreements	$ 82,500,000		$ 82,500,000
Beginning claims | claim	29,407	29,162	29,138	29,056	29,056
New claims | claim	772	577	1,505	1,258	2,620
Settlements | claim	(176)	(264)	(336)	(429)	(885)
Dismissals | claim	(215)	(548)	(519)	(958)	(1,653)
Ending claims | claim	29,788	28,927	29,788	28,927	29,138	29,056
Gross Settlement And Defense Incurred Costs	$ 12,200,000	$ 11,200,000	$ 21,300,000	$ 23,900,000	$ 50,900,000
Payments for asbestos-related fees and costs, net of insurance recoveries	9,400,000	$ 7,400,000	20,200,000	$ 19,200,000	$ 31,100,000
Cumulative Asbestos Settlement Cost Per Resolved Claim	$ 4,900		$ 4,900
New York | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Ending claims | claim	18,000		18,000
us-gaap_LossContingencyPendingClaimsNumber (nonmalignancy) | claim	16,000		16,000