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Stock-Based Compensation - Weighted-Average Assumptions Utilized to Value Stock Options (Detail) (USD $)
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3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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Mar. 28, 2015
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Mar. 29, 2014
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Mar. 28, 2015
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Mar. 29, 2014
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Risk-free interest rate | 1.70% | 1.30% | 1.70% | 1.20% |
| Expected volatility | 38.60% | 41.40% | 38.60% | 41.40% |
| Expected life (in years) | 5 years 4 months | 4 years 6 months | 5 years 4 months | 4 years 5 months |
| Dividend yield | $ 0 | $ 0 | $ 0 | $ 0 |
| Weighted average fair value of options granted | $ 10.36 | $ 7.82 | $ 9.55 | $ 7.65 |