Fair Value Measurements and Investments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Assets
Investment securities	$ 5,116	$ 5,261
Level 1 \| Recurring
Assets
Total	16,938	16,999
Liabilities
Total	181	146
Level 1 \| Recurring \| Deferred compensation liability
Liabilities
Deferred compensation liability	181	146
Level 1 \| Recurring \| Derivative instruments
Liabilities
Derivative instruments	0	0
Level 1 \| Money market funds \| Recurring
Assets
Cash equivalents and restricted cash equivalents:	12,605	11,736
Other current and non-current assets:	23	22
Level 1 \| U.S. Treasury securities \| Recurring
Assets
Cash equivalents and restricted cash equivalents:	175	799
Investment securities	3,788	4,005
Level 1 \| Marketable equity securities \| Recurring
Assets
Marketable equity securities	347	437
Level 1 \| U.S. government-sponsored debt securities \| Recurring
Assets
Investment securities	0	0
Level 1 \| Derivative instruments \| Recurring
Assets
Other current and non-current assets:	0	0
Level 2 \| Recurring
Assets
Total	1,350	1,588
Liabilities
Total	482	418
Level 2 \| Recurring \| Deferred compensation liability
Liabilities
Deferred compensation liability	0	0
Level 2 \| Recurring \| Derivative instruments
Liabilities
Derivative instruments	482	418
Level 2 \| Money market funds \| Recurring
Assets
Cash equivalents and restricted cash equivalents:	0	0
Other current and non-current assets:	0	0
Level 2 \| U.S. Treasury securities \| Recurring
Assets
Cash equivalents and restricted cash equivalents:	0	0
Investment securities	0	0
Level 2 \| Marketable equity securities \| Recurring
Assets
Marketable equity securities	0	0
Level 2 \| U.S. government-sponsored debt securities \| Recurring
Assets
Investment securities	1,153	457
Level 2 \| Derivative instruments \| Recurring
Assets
Other current and non-current assets:	$ 197	$ 1,131

Fair value portion of accrued expenses.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value of financial and nonfinancial obligations.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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