Goodwill and Intangible Assets - Intangible Assets (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	$ 875.5	$ 875.5
Accumulated Impairment Charges	(1.5)	(1.5)
Accumulated Amortization	(350.6)	(308.0)
Foreign Currency Translation	(0.1)	(1.4)
Intangible assets, net	523.3	564.6
Completed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	446.4	446.4
Accumulated Impairment Charges	(0.1)	(0.1)
Accumulated Amortization	(203.2)	(178.3)
Foreign Currency Translation	(0.1)	(0.2)
Intangible assets, net	243.0	267.8
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	308.2	308.2
Accumulated Impairment Charges	(1.4)	(1.4)
Accumulated Amortization	(99.6)	(84.2)
Foreign Currency Translation	0.2	(1.4)
Intangible assets, net	207.4	221.2
Patents, Trademarks, Trade Names and Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	120.9	120.9
Accumulated Amortization	(47.8)	(45.5)
Foreign Currency Translation	(0.2)	0.2
Intangible assets, net	$ 72.9	$ 75.6