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Stock-Based Compensation - Weighted-Average Assumptions Utilized to Value Stock Options (Detail) - USD ($)
3 Months Ended
Dec. 31, 2016
Dec. 26, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate 1.80% 1.60%
Expected volatility 36.60% 37.80%
Expected life (in years) 4 years 8 months 8 days 4 years 8 months 8 days
Dividend yield $ 0 $ 0
Weighted average fair value of options granted $ 12.18 $ 13.13