Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Unrecognized Tax Benefits [Roll Forward]
Beginning balance	$ 527	$ 499	$ 499
Additions for tax positions related to the current year	6	2	62
Additions for tax positions of prior years	18	50	2
Reductions for tax positions of prior years	(9)	(5)	(52)
Settlements with taxing authorities	(115)	(11)	(3)
Statute closings	(5)	(8)	(9)
Ending balance	$ 422	$ 527	$ 499

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

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 217
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-217

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
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-Paragraph 15A
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Section 45
-Paragraph 10B
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-URI https://asc.fasb.org/1943274/2147482525/740-10-45-10B

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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- Definition

Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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- Definition

Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

+ References

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