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Debt - 2014 Credit Agreement (Details)			12 Months Ended
	Jun. 25, 2021 USD ($)	Feb. 08, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Apr. 13, 2021 USD ($)
Debt agreements
Proceeds from secured delayed draw term loan facility			$ 3,638,916,000	$ 4,452,078,000	$ 7,700,774,000
Credit Agreement
Debt agreements
Consolidated leverage ratio		4.00	2.4
Consolidated interest coverage ratio		3.00
Credit Agreement | Term loan A
Debt agreements
Maximum borrowing capacity		$ 246,968,737.50
Proceeds from secured delayed draw term loan facility	$ 215,000,000
Credit Agreement | Term loan A | LIBOR
Debt agreements
Interest rate, basis spread (as a percent)		1.50%
Credit Agreement | Term loan B | Base Rate
Debt agreements
Interest rate, basis spread (as a percent)		0.50%
Credit Agreement | Term B facility
Debt agreements
Maximum borrowing capacity						$ 700,000,000
Consolidated leverage ratio						1.75
Consolidated interest coverage ratio						0.75
Credit Agreement | Revolving credit facility
Debt agreements
Maximum borrowing capacity		$ 1,150,000,000
Current borrowing capacity			$ 1,144,800,000	1,331,000,000.0
Outstanding letters of credit			$ 5,200,000	$ 19,000,000.0
2024 Senior Notes
Debt agreements
Cash tender						$ 700,000,000
Interest rate (as a percent)	5.875%					5.875%

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- Definition

Represents the consolidated interest coverage ratio.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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-Name Accounting Standards Codification
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-SubTopic 10
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Face (par) amount of the original debt instrument that was repurchased.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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Indebtedness divided by net capital.

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