Employee Stock Plans - Fair Value with Weighted Average Assumptions (Detail) - $ / shares	12 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Sep. 27, 2013
Employee Stock Option plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	4 years 1 month 24 days	4 years 1 month 17 days	4 years 9 months 4 days
Risk-free interest rate (as a percent)	1.30%	1.20%	0.60%
Expected volatility (as a percent)	22.10%	24.60%	32.20%
Expected dividend (as a percent)	0.00%	0.00%	0.00%
Weighted average fair value at grant date (in dollars per share)	$ 18.52	$ 18.24	$ 19.73
Employee Stock Purchase Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months
Risk-free interest rate (as a percent)	0.10%	0.10%	0.10%
Expected volatility (as a percent)	12.70%	12.80%	16.50%
Expected dividend (as a percent)	0.00%	0.00%	0.00%
Weighted average fair value at grant date (in dollars per share)	$ 15.87	$ 14.20	$ 12.95