Commitments and Contingencies - Accrued Product Warranty (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Oct. 02, 2015
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Accrued product warranty, at beginning of period	$ 45.9	$ 49.3
Charged to cost of revenues	59.4	50.8
Actual product warranty expenditures	(50.5)	(54.2)
Accrued product warranty, at end of period	$ 54.8	$ 45.9