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Stockholders' Equity and Stock-Based Compensation - Information Pertaining to Stock Options Granted and Related Assumptions (Detail) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
Sep. 30, 2017
Sep. 24, 2016
Sep. 26, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures 1.0 1.1 1.3
Weighted-average exercise price $ 38.07 $ 39.32 $ 27.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value $ 12.33 $ 0 $ 0
Assumptions:      
Risk-free interest rates 1.80% 1.60% 1.70%
Expected life (in years) 4 years 8 months 15 days 4 years 8 months 15 days 5 years 4 months 6 days
Expected volatility 36.60% 37.80% 38.60%
Dividend yield $ 0.0 $ 0.0 $ 0.0