Accrued Product Warranty (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 26, 2014	Sep. 27, 2013
Commitments And Contingencies Disclosure [Abstract]
Accrued product warranty, at beginning of period	$ 53.2	$ 52.8
Charged to cost of revenues	51.9	57.7
Actual product warranty expenditures	(55.8)	(57.3)
Accrued product warranty, at end of period	$ 49.3	$ 53.2