Stock-Based Compensation - Weighted-Average Assumptions Utilized to Value Stock Options (Detail) (USD $)	3 Months Ended		6 Months Ended
	Mar. 30, 2013	Mar. 24, 2012	Mar. 30, 2013	Mar. 24, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	0.50%	0.70%	0.50%	0.70%
Expected volatility	43.70%	46.90%	43.70%	46.90%
Expected life (in years)	4 years 4 months 24 days	4 years 3 months 18 days	4 years 4 months 24 days	4 years 3 months 18 days
Dividend yield
Weighted average fair value of options granted	$ 5.83	$ 6.63	$ 6.99	$ 6.42