Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Long-Term Debt	$ 14,738	$ 13,886
3.875% Notes due May 15, 2024
Debt Instrument [Line Items]
Long-Term Debt	$ 0	145
3.363% Notes due June 6, 2024
Debt Instrument [Line Items]
Interest rate	3.363%
Long-Term Debt	$ 0	996
3.734% Notes due December 15, 2024
Debt Instrument [Line Items]
Interest rate	3.734%
Long-Term Debt	$ 874	873
3.020% Notes due May 24, 2025
Debt Instrument [Line Items]
Interest rate	3.02%
Long-Term Debt	$ 306	275
0.034% Notes due August 13, 2025
Debt Instrument [Line Items]
Interest rate	0.034%
Long-Term Debt	$ 528	485
1.208% Notes due June 4, 2026
Debt Instrument [Line Items]
Interest rate	1.208%
Long-Term Debt	$ 634	583
6.700% Notes due December 1, 2026
Debt Instrument [Line Items]
Interest rate	6.70%
Long-Term Debt	$ 161	165
1.900% Notes due December 15, 2026
Debt Instrument [Line Items]
Interest rate	1.90%
Long-Term Debt	$ 528	485
3.700% Notes due June 6, 2027
Debt Instrument [Line Items]
Interest rate	3.70%
Long-Term Debt	$ 1,719	1,718
7.000% Debentures due August 1, 2027
Debt Instrument [Line Items]
Interest rate	7.00%
Long-Term Debt	$ 119	119
4.693% Notes due February 13, 2028
Debt Instrument [Line Items]
Interest rate	4.693%
Long-Term Debt	$ 796	0
6.700% Debentures due August 1, 2028
Debt Instrument [Line Items]
Interest rate	6.70%
Long-Term Debt	$ 115	116
0.334% Notes due August 13, 2028
Debt Instrument [Line Items]
Interest rate	0.334%
Long-Term Debt	$ 949	872
3.553% Notes due September 13, 2029
Debt Instrument [Line Items]
Interest rate	3.553%
Long-Term Debt	$ 842	0
2.823% Notes due May 20, 2030
Debt Instrument [Line Items]
Interest rate	2.823%
Long-Term Debt	$ 745	745
1.957% Notes due February 11, 2031
Debt Instrument [Line Items]
Interest rate	1.957%
Long-Term Debt	$ 993	992
4.298% Notes due August 22, 2032
Debt Instrument [Line Items]
Interest rate	4.298%
Long-Term Debt	$ 496	495
1.213% Notes due February 12, 2036
Debt Instrument [Line Items]
Interest rate	1.213%
Long-Term Debt	$ 631	580
6.000% Notes due May 15, 2039
Debt Instrument [Line Items]
Interest rate	6.00%
Long-Term Debt	$ 121	121
5.000% Notes due November 12, 2040
Debt Instrument [Line Items]
Interest rate	5.00%
Long-Term Debt	$ 90	90
1.336% Notes due August 13, 2041
Debt Instrument [Line Items]
Interest rate	1.336%
Long-Term Debt	$ 945	869
4.875% Notes due May 15, 2044
Debt Instrument [Line Items]
Interest rate	4.875%
Long-Term Debt	$ 245	246
4.685% Notes due December 15, 2044
Debt Instrument [Line Items]
Interest rate	4.685%
Long-Term Debt	$ 899	911
4.669% Notes due June 6, 2047
Debt Instrument [Line Items]
Interest rate	4.669%
Long-Term Debt	$ 1,445	1,449
3.794% Notes due May 20, 2050
Debt Instrument [Line Items]
Interest rate	3.794%
Long-Term Debt	$ 554	554
Other long-term debt
Debt Instrument [Line Items]
Long-Term Debt	$ 2	$ 0