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Stock-Based Compensation - Weighted-Average Assumptions Utilized to Value Stock Options (Detail) - USD ($)
3 Months Ended 6 Months Ended
Mar. 31, 2018
Apr. 01, 2017
Mar. 31, 2018
Apr. 01, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Risk-free interest rate 2.10% 1.80% 2.10% 1.80%
Expected volatility 35.30% 36.50% 35.30% 36.60%
Expected life (in years) 4 years 8 months 8 days 4 years 8 months 8 days 4 years 8 months 8 days 4 years 8 months
Dividend yield $ 0 $ 0 $ 0 $ 0
Weighted average fair value of options granted $ 12.53 $ 13.44 $ 12.98 $ 12.28