Employee Stock Plans - Summary the Effect of Recording Pre-Tax Share-Based Compensation Expense for Equity Incentive Awards (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Oct. 02, 2015	Sep. 26, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 48.3	$ 46.3	$ 39.6
Equity Option
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	11.1	11.3	9.5
Restricted Stock Units and Restricted Stock Awards
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	33.0	31.4	26.6
Employee Stock Purchase Plans
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 4.2	$ 3.6	$ 3.5