Commitments and Contingencies (Asbestos Liability) (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 ($)	Mar. 31, 2021 claim	Mar. 31, 2020 claim	Aug. 21, 2012 USD ($)
Loss Contingencies [Line Items]
Payments for asbestos-related fees and costs, net of insurance recoveries			$ 20,200,000	$ 19,200,000
Estimated payments to current and future claimants	$ 36,000,000,000		36,000,000,000
Current portion of total estimated liability	$ 66,500,000		$ 66,500,000		$ 66,500,000
Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Pending claims | claim	29,788	28,927	29,788	28,927	29,138	29,056		29,407	29,162
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 claims resolved | claim	142,000		142,000
Settlement cost	$ 692,000,000		$ 692,000,000
Average settlement cost per resolved claim			13,900			$ 15,800	$ 11,300
Additional liability						255,000,000
Liability for claims	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 portion of total estimated liability	66,500,000		66,500,000		66,500,000
Aggregate value of policy buyout agreements	82,500,000		82,500,000
Estimated Percentage Of Insurance Which Covers Asbestos Costs						14.00%
Insurance reimbursement asset	80,000,000		80,000,000		87,000,000	$ 98,000,000
Gross Settlement And Defense Incurred Costs	$ 12,200,000	$ 11,200,000	$ 21,300,000	$ 23,900,000	$ 50,900,000
Asbestos Commitments and Contingencies | Ronald Dummitt
Loss Contingencies [Line Items]
Court Judgment										$ 4,900,000
New York | Asbestos Commitments and Contingencies
Loss Contingencies [Line Items]
Pending claims | claim	18,000		18,000