Stockholders' Equity - RSU activity (Details) - $ / shares		12 Months Ended
Oct. 01, 2019	Sep. 30, 2019	Sep. 30, 2018
Weighted Average Grant-Date Fair Value
Shares available for future grants		1,637,274
Subsequent event
Number of Shares
Vested (in shares)	(148,995)
Service-Based RSUs
Number of Shares
Balance unvested at the beginning of the period (in shares)	422,094	366,460	366,331
Granted (in shares)		239,874	165,271
Vested (in shares)		(145,409)	(147,832)
Forfeited (in shares)		(38,831)	(17,310)
Balance unvested at the end of the period (in shares)		422,094	366,460
Weighted Average Grant-Date Fair Value
Balance unvested at the beginning of the period (in dollars per share)	$ 58.84	$ 52.31	$ 45.99
Granted (in dollars per share)		63.25	61.06
Vested (in dollars per share)		50.76	46.86
Forfeited (in dollars per share)		54.67	48.62
Balance unvested at the end of the period (in dollars per share)		$ 58.84	$ 52.31
Performance-based RSUs
Number of Shares
Balance unvested at the beginning of the period (in shares)	315,262	635,628	678,856
Granted (in shares)			179,162
Forfeited (in shares)		(320,366)	(222,390)
Balance unvested at the end of the period (in shares)		315,262	635,628
Weighted Average Grant-Date Fair Value
Balance unvested at the beginning of the period (in dollars per share)	$ 55.67	$ 50.11	$ 46.59
Granted (in dollars per share)			61.40
Forfeited (in dollars per share)		44.63	48.46
Balance unvested at the end of the period (in dollars per share)		$ 55.67	$ 50.11
Performance and market-based RSUs
Number of Shares
Balance unvested at the beginning of the period (in shares)	227,402
Granted (in shares)		237,616
Forfeited (in shares)		(10,214)
Balance unvested at the end of the period (in shares)		227,402
Weighted Average Grant-Date Fair Value
Balance unvested at the beginning of the period (in dollars per share)	$ 66.77
Granted (in dollars per share)		$ 66.79
Forfeited (in dollars per share)		67.40
Balance unvested at the end of the period (in dollars per share)		$ 66.77

No definition available.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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