Income Taxes - Significant Components of Company's Income Tax Provision from Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Tax expense at Ireland statutory rate of 12.5%	$ 214	$ 214	$ 327
U.S. state income tax, net of federal benefit	39	(23)	34
Income subject to the U.S. federal tax rate	56	(95)	3
Income subject to rates different than the statutory rate	92	125	30
Reserve and valuation allowance adjustments	(559)	(274)	66
Intellectual property transactions and adjustments	(176)	0	417
Restructuring and impairment costs	11	40	(9)
Income tax provision (benefit)	$ (323)	$ (13)	$ 868

Effective Income Tax Reconciliation, Restructuring and Impairment Costs, Amount

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Income Tax Reconciliation, Change In Deferred Tax Assets Reserve and Valuation Allowance

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Income Tax Reconciliation Foreign Income Tax Rate Differential, Non-US

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to disposition of asset. Includes, but is not limited to, intra-entity transfer of asset other than inventory.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to state and local income tax expense (benefit).

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