Goodwill and Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 28, 2018	Sep. 29, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	$ 191.1	$ 141.4
Accumulated amortization	(98.8)	(78.6)
Net carrying amount	92.3	62.8
Intangible assets, gross carrying amount	199.9	150.2
Intangible assets, net carrying amount	101.1	71.6
In Process Research and Development
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross carrying amount	8.8	8.8
Technologies and patents
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	139.6	102.0
Accumulated amortization	(73.9)	(60.9)
Net carrying amount	65.7	41.1
Customer contracts and supplier relationship
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	44.9	33.9
Accumulated amortization	(19.1)	(14.3)
Net carrying amount	25.8	19.6
Other
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	6.6	5.5
Accumulated amortization	(5.8)	(3.4)
Net carrying amount	$ 0.8	$ 2.1