Fair Value Measurements and Investments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Jun. 30, 2022	Sep. 30, 2021
Level 1
Assets
Total	$ 17,082	$ 17,658
Liabilities
Deferred compensation liability	153	167
Derivative instruments	0	0
Total	153	167
Level 1 | Money market funds
Assets
Cash equivalents and restricted cash equivalents:	10,894	11,779
Other current and non-current assets:	4	4
Level 1 | Marketable equity securities
Assets
Marketable equity securities	564	490
Level 1 | U.S. government-sponsored debt securities
Assets
Cash equivalents and restricted cash equivalents:	0	0
Investment securities	0	0
Level 1 | U.S. Treasury securities
Assets
Cash equivalents and restricted cash equivalents:	700	2,400
Investment securities	4,920	2,985
Level 1 | Derivative instruments
Assets
Other current and non-current assets:	0	0
Level 2
Assets
Total	779	755
Liabilities
Deferred compensation liability	0	0
Derivative instruments	292	109
Total	292	109
Level 2 | Money market funds
Assets
Cash equivalents and restricted cash equivalents:	0	0
Other current and non-current assets:	0	0
Level 2 | Marketable equity securities
Assets
Marketable equity securities	0	0
Level 2 | U.S. government-sponsored debt securities
Assets
Cash equivalents and restricted cash equivalents:	0	100
Investment securities	15	245
Level 2 | U.S. Treasury securities
Assets
Cash equivalents and restricted cash equivalents:	0	0
Investment securities	0	0
Level 2 | Derivative instruments
Assets
Other current and non-current assets:	$ 764	$ 410