Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021	Mar. 31, 2021
Debt Instrument [Line Items]
Long-Term Debt	$ 13,886	$ 17,110
1.000% Notes due December 15, 2022
Debt Instrument [Line Items]
Interest rate	1.00%
Long-Term Debt	$ 0	579
1.401% Notes due May 24, 2023
Debt Instrument [Line Items]
Interest rate	1.401%
Long-Term Debt	$ 0	347
0.632% Notes due June 4, 2023
Debt Instrument [Line Items]
Interest rate	0.632%
Long-Term Debt	$ 0	$ 926
0.000% Notes due August 13, 2023
Debt Instrument [Line Items]
Interest rate	0.00%	0.00%
Long-Term Debt	$ 0	$ 463
3.875% Notes due May 15, 2024
Debt Instrument [Line Items]
Interest rate	3.875%	3.875%
Long-Term Debt	$ 145	$ 146
3.363% Notes due June 6, 2024
Debt Instrument [Line Items]
Interest rate	3.363%	3.363%
Long-Term Debt	$ 996	$ 994
3.734% Notes due December 15, 2024
Debt Instrument [Line Items]
Interest rate	3.734%	3.734%
Long-Term Debt	$ 873	$ 873
3.020% Notes due May 24, 2025
Debt Instrument [Line Items]
Interest rate	3.02%
Long-Term Debt	$ 275	$ 336
0.034% Notes due August 13, 2025
Debt Instrument [Line Items]
Interest rate	0.034%	0.034%
Long-Term Debt	$ 485	$ 577
1.208% Notes due June 4, 2026
Debt Instrument [Line Items]
Interest rate	1.208%
Long-Term Debt	$ 583	693
6.700% Notes due December 1, 2026
Debt Instrument [Line Items]
Interest rate	6.70%
Long-Term Debt	$ 165	168
1.900% Notes due December 15, 2026
Debt Instrument [Line Items]
Interest rate	1.90%
Long-Term Debt	$ 485	577
3.700% Notes due June 6, 2027
Debt Instrument [Line Items]
Interest rate	3.70%
Long-Term Debt	$ 1,718	1,716
7.000% Debentures due August 1, 2027
Debt Instrument [Line Items]
Interest rate	7.00%
Long-Term Debt	$ 119	174
6.700% Debentures due August 1, 2028
Debt Instrument [Line Items]
Interest rate	6.70%
Long-Term Debt	$ 116	$ 173
0.334% Notes due August 13, 2028
Debt Instrument [Line Items]
Interest rate	0.334%	0.334%
Long-Term Debt	$ 872	$ 1,037
2.823% Notes due May 20, 2030
Debt Instrument [Line Items]
Interest rate	2.823%
Long-Term Debt	$ 745	744
1.957% Notes due February 11, 2031
Debt Instrument [Line Items]
Interest rate	1.957%		1.957%
Long-Term Debt	$ 992	992
4.298% Notes due August 22, 2032
Debt Instrument [Line Items]
Interest rate	4.298%
Long-Term Debt	$ 495	0
1.213% Notes due February 12, 2036
Debt Instrument [Line Items]
Interest rate			1.213%
Long-Term Debt	$ 580	690
6.000% Notes due May 15, 2039
Debt Instrument [Line Items]
Interest rate	6.00%
Long-Term Debt	$ 121	246
5.000% Notes due November 12, 2040
Debt Instrument [Line Items]
Interest rate	5.00%
Long-Term Debt	$ 90	$ 124
1.336% Notes due August 13, 2041
Debt Instrument [Line Items]
Interest rate	1.336%	1.336%
Long-Term Debt	$ 869	$ 1,034
4.875% Notes due May 15, 2044
Debt Instrument [Line Items]
Interest rate	4.875%
Long-Term Debt	$ 246	246
4.685% Notes due December 15, 2044
Debt Instrument [Line Items]
Interest rate	4.685%
Long-Term Debt	$ 911	1,033
4.669% Notes due June 6, 2047
Debt Instrument [Line Items]
Interest rate	4.669%
Long-Term Debt	$ 1,449	1,481
3.794% Notes due May 20, 2050
Debt Instrument [Line Items]
Interest rate	3.794%
Long-Term Debt	$ 554	$ 742