Commitments and Contingencies (Schedule Of Settlement And Defense Costs) (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 ($)	Mar. 31, 2021 claim	Mar. 31, 2020 claim
Loss Contingencies [Line Items]
Pre-tax cash payments			$ 20,200,000	$ 19,200,000
Estimated Funds Available From Post Bankruptcy Trusts To Pay Current And Future Claimants	$ 36,000,000,000		36,000,000,000
Current asbestos liability	$ 66,500,000		$ 66,500,000		$ 66,500,000
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Estimated Percentage Of Insurance Which Covers Asbestos Costs						14.00%
Asbestos Cumulative Claims Resolved | claim	142,000		142,000
Loss Contingency, Pending Claims, Number | claim	29,788	28,927	29,788	28,927	29,138	29,056		29,407	29,162
Settlement / indemnity costs incurred (1)	$ 8,400,000	$ 7,600,000	$ 13,900,000	$ 15,800,000	$ 35,300,000
Defense costs incurred (1)	3,800,000	3,600,000	7,400,000	8,100,000	15,600,000
Gross Settlement And Defense Incurred Costs	12,200,000	11,200,000	21,300,000	23,900,000	50,900,000
Settlement / indemnity payments	9,400,000	5,900,000	19,500,000	16,900,000	24,700,000
Defense payments	4,200,000	4,200,000	7,400,000	8,500,000	16,700,000
Insurance receipts	(4,200,000)	(2,700,000)	(6,700,000)	(6,200,000)	(10,300,000)
Pre-tax cash payments	9,400,000	$ 7,400,000	20,200,000	$ 19,200,000	31,100,000
Cumulative Related Settlement Cost Incurred Before Insurance Recoveries	692,000,000		692,000,000
Cumulative Asbestos Settlement Cost Per Resolved Claim	4,900		4,900
Asbestos Settlement Cost Per Resolved Claim			13,900			$ 15,800	$ 11,300
Increase In Total Asbestos Liability						255,000,000
Insurance Receivable Asbestos	80,000,000		80,000,000		87,000,000	98,000,000
Asbestos Liability	643,000,000		643,000,000		670,000,000	$ 712,000,000
Percentage Of Asbestos Liability Attributable To Settlement And Defense Costs For Future Claims						85.00%
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