Goodwill And Intangible Assets (Summary Of Intangible Assets) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	18 years
Intangible Assets, Gross (Excluding Goodwill)	$ 946.6	$ 890.0
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	11.2
Finite-Lived Intangible Assets, Amortization Expense, Year Two	42.5
Finite-Lived Intangible Assets, Amortization Expense, Year Three	42.2
Intangible assets, net	526.9	505.1	$ 481.8
Finite-Lived Intangible Assets, Accumulated Amortization	419.7	384.9
Finite-Lived Intangible Assets, Amortization Expense, Year Four	42.0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 318.7
Intellectual Property Rights
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years 7 months 6 days
Intangible Assets, Gross (Excluding Goodwill)	$ 136.7	134.2
Intangible assets, net	79.3	77.4
Finite-Lived Intangible Assets, Accumulated Amortization	$ 57.4	56.8
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	18 years 4 months 24 days
Intangible Assets, Gross (Excluding Goodwill)	$ 656.1	603.1
Intangible assets, net	388.5	361.8
Finite-Lived Intangible Assets, Accumulated Amortization	$ 267.6	241.3
Drawings
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	40 years
Intangible Assets, Gross (Excluding Goodwill)	$ 11.1	11.1
Intangible assets, net	0.6	0.6
Finite-Lived Intangible Assets, Accumulated Amortization	$ 10.5	10.5
Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	11 years 9 months 18 days
Intangible Assets, Gross (Excluding Goodwill)	$ 142.7	141.6
Intangible assets, net	58.5	65.3
Finite-Lived Intangible Assets, Accumulated Amortization	$ 84.2	$ 76.3