Fair Value of Employee Stock Purchase Plan with Weighted Average Assumptions (Detail) (USD $)	3 Months Ended
	Dec. 27, 2013	Dec. 28, 2012
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months
Risk-free interest rate	0.10%	0.20%
Expected volatility	14.50%	19.30%
Expected dividend	0.00%	0.00%
Weighted average fair value at grant date	$ 13.98	$ 13.45
Employee Stock Option Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	4 years 10 months 13 days	4 years 9 months 4 days
Risk-free interest rate	1.30%	0.60%
Expected volatility	27.20%	32.40%
Expected dividend	0.00%	0.00%
Weighted average fair value at grant date	$ 19.44	$ 19.76