Fair Value of Employee Stock Purchase Plan with Weighted Average Assumptions (Detail) (Employee Stock Plan, USD $)	12 Months Ended
	Sep. 28, 2012	Sep. 30, 2011	Oct. 01, 2010
Employee Stock Option Disclosures
Expected term (in years)	4 years 7 months 21 days	4 years 9 months	4 years 8 months 19 days
Risk-free interest rate	0.80%	2.00%	2.00%
Expected volatility	36.90%	35.50%	37.30%
Expected dividend yield	0.00%	0.00%	0.00%
Weighted average fair value at grant date	$ 18.75	$ 23.26	$ 18.17
Employee Stock Purchase Plan
Employee Stock Option Disclosures
Expected term (in years)	6 months	6 months	0 years	[1]
Risk-free interest rate	0.10%	0.10%
Expected volatility	19.30%	14.00%
Expected dividend yield	0.00%	0.00%
Weighted average fair value at grant date	$ 12.17	$ 12.61

[1] No purchases were made under an employee stock purchase plan in fiscal year 2010.