Debt (Details) - USD ($) $ in Millions	Mar. 31, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Unamortized discounts and debt issuance costs	$ (132)	$ (142)
Hedge accounting fair value adjustments	(110)	(133)
Total carrying value of debt	20,762	20,836
Current maturities of debt	3,948	0
Long-term debt	16,814	20,836
Senior Notes
Debt Instrument [Line Items]
Senior notes	$ 21,004	21,111
Senior Notes | 3.15% Senior Notes due December 2025 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	3.15%
Senior notes	$ 4,000	4,000
Effective interest rate (percent)	3.26%
Senior Notes | 1.90% Senior Notes due April 2027 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	1.90%
Senior notes	$ 1,500	1,500
Effective interest rate (percent)	2.02%
Senior Notes | 0.75% Senior Notes due August 2027 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	0.75%
Senior notes	$ 500	500
Effective interest rate (percent)	0.84%
Senior Notes | 2.75% Senior Notes due September 2027 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	2.75%
Senior notes	$ 750	750
Effective interest rate (percent)	2.91%
Senior Notes | 2.05% Senior Notes due April 2030 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	2.05%
Senior notes	$ 1,500	1,500
Effective interest rate (percent)	2.13%
Senior Notes | 1.10% Senior Notes due February 2031 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	1.10%
Senior notes	$ 1,000	1,000
Effective interest rate (percent)	1.20%
Senior Notes | 4.15% Senior Notes due December 2035 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	4.15%
Senior notes	$ 1,500	1,500
Effective interest rate (percent)	4.23%
Senior Notes | 2.70% Senior Notes due April 2040 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	2.70%
Senior notes	$ 1,000	1,000
Effective interest rate (percent)	2.80%
Senior Notes | 4.30% Senior Notes due December 2045 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	4.30%
Senior notes	$ 3,500	3,500
Effective interest rate (percent)	4.37%
Senior Notes | 3.65% Senior Notes due September 2047 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	3.65%
Senior notes	$ 750	750
Effective interest rate (percent)	3.73%
Senior Notes | 2.00% Senior Notes due August 2050 | U.S.
Debt Instrument [Line Items]
Stated interest rate (percent)	2.00%
Senior notes	$ 1,750	1,750
Effective interest rate (percent)	2.09%
Senior Notes | 1.50% Senior Notes due June 2026 | Europe
Debt Instrument [Line Items]
Stated interest rate (percent)	1.50%
Senior notes	$ 1,464	1,513
Effective interest rate (percent)	1.71%
Senior Notes | 2.00% Senior Notes due June 2029 | Europe
Debt Instrument [Line Items]
Stated interest rate (percent)	2.00%
Senior notes	$ 1,085	1,120
Effective interest rate (percent)	2.13%
Senior Notes | 2.375% Senior Notes due June 2034 | Europe
Debt Instrument [Line Items]
Stated interest rate (percent)	2.375%
Senior notes	$ 705	$ 728
Effective interest rate (percent)	2.53%