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Stock-Based Compensation - Weighted-Average Assumptions Utilized to Value Stock Options (Detail) - USD ($)
3 Months Ended
Dec. 26, 2015
Dec. 27, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate 1.60% 1.70%
Expected volatility 37.80% 38.60%
Expected life (in years) 4 years 8 months 5 years 3 months 3 days
Dividend yield $ 0 $ 0
Weighted average fair value of options granted $ 13.13 $ 9.44