Stockholders' Equity and Stock-Based Compensation - Assumptions to Value Stock Options (Detail) - USD ($)	12 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Assumptions:
Risk-free interest rates	1.70%	3.00%	2.10%
Expected life (in years)	4 years 9 months 18 days	4 years 9 months 18 days	4 years 8 months 12 days
Expected volatility	33.60%	34.30%	35.30%
Dividend yield	$ 0	$ 0	$ 0
ESPP
Assumptions:
Risk-free interest rates	1.32%	2.27%	1.62%
Expected life (in years)	6 months	6 months	6 months
Expected volatility	26.90%	27.10%	25.00%
Dividend yield	$ 0	$ 0	$ 0

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Disclosure of the weighted average expected dividend for an entity using a valuation technique with different dividend rates during the contractual term.

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- Definition

Rate of weighted-average expected volatility for award under share-based payment arrangement.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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