Goodwill and Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 29, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	$ 141.4	$ 137.5
Accumulated amortization	(78.6)	(62.2)
Net carrying amount	62.8	75.3
Intangible assets, gross carrying amount	150.2	146.3
Intangible assets, accumulated amortization	(78.6)	(62.2)
Intangible assets, net carrying amount	71.6	84.1
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	102.0	99.6
Accumulated amortization	(60.9)	(50.2)
Net carrying amount	41.1	49.4
Customer contracts and supplier relationship
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	33.9	32.3
Accumulated amortization	(14.3)	(10.8)
Net carrying amount	19.6	21.5
Other
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying amount	5.5	5.6
Accumulated amortization	(3.4)	(1.2)
Net carrying amount	$ 2.1	$ 4.4