Benefit Plans - Fair Value Measurements of Plan Assets (Details) - Pension Plans - USD ($) $ in Millions | Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2022 |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | $ 2,557 | $ 2,129 | $ 2,242 |
United States | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 1,676 | 1,382 | |
United States | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 518 | 443 | |
United States | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 159 | 53 | |
United States | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 31 | 17 | |
United States | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 53 | 46 | |
United States | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 582 | 469 | |
United States | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 172 | 202 | |
United States | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 162 | 151 | |
International plans | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 880 | 748 | |
International plans | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 114 | 122 | |
International plans | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 9 | 9 | |
International plans | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 223 | 197 | |
International plans | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 52 | 43 | |
International plans | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 196 | 173 | |
International plans | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 13 | 10 | |
International plans | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 117 | 55 | |
International plans | Real estate | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 44 | 36 | |
International plans | Insurance contracts | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 113 | 103 | |
Net Asset Value | United States | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 146 | 138 | |
Net Asset Value | United States | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Net Asset Value | United States | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Net Asset Value | United States | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Net Asset Value | United States | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Net Asset Value | United States | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 71 | 59 | |
Net Asset Value | United States | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Net Asset Value | United States | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 75 | 79 | |
Level 1 | United States | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 1,240 | 1,012 | |
Level 1 | United States | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 296 | 260 | |
Level 1 | United States | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 149 | 43 | |
Level 1 | United States | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 1 | United States | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 25 | 24 | |
Level 1 | United States | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 512 | 410 | |
Level 1 | United States | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 172 | 202 | |
Level 1 | United States | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 87 | 72 | |
Level 1 | International plans | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 600 | 499 | |
Level 1 | International plans | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 92 | 100 | |
Level 1 | International plans | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 7 | 8 | |
Level 1 | International plans | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 188 | 165 | |
Level 1 | International plans | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 44 | 34 | |
Level 1 | International plans | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 166 | 147 | |
Level 1 | International plans | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 11 | 8 | |
Level 1 | International plans | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 92 | 35 | |
Level 1 | International plans | Real estate | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 1 | 1 | |
Level 1 | International plans | Insurance contracts | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 2 | United States | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 291 | 231 | |
Level 2 | United States | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 222 | 182 | |
Level 2 | United States | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 10 | 10 | |
Level 2 | United States | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 31 | 17 | |
Level 2 | United States | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 28 | 22 | |
Level 2 | United States | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 2 | United States | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 2 | United States | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 2 | International plans | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 85 | 74 | |
Level 2 | International plans | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 9 | 10 | |
Level 2 | International plans | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 2 | 2 | |
Level 2 | International plans | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 28 | 26 | |
Level 2 | International plans | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 9 | 9 | |
Level 2 | International plans | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 1 | |
Level 2 | International plans | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 2 | International plans | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 3 | 1 | |
Level 2 | International plans | Real estate | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 34 | 26 | |
Level 2 | International plans | Insurance contracts | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | United States | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | International plans | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 195 | 175 | |
Level 3 | International plans | Corporate bonds | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 13 | 12 | |
Level 3 | International plans | Government and agency-U.S. | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | International plans | Government and agency-Foreign | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 7 | 6 | |
Level 3 | International plans | Other fixed income | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 0 | 0 | |
Level 3 | International plans | Equity securities | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 30 | 25 | |
Level 3 | International plans | Cash and cash equivalents | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 2 | 2 | |
Level 3 | International plans | Other | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 22 | 19 | |
Level 3 | International plans | Real estate | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | 9 | 9 | |
Level 3 | International plans | Insurance contracts | | | |
Defined Benefit Plan Disclosure [Line Items] | | | |
Fair value of plan assets | $ 113 | $ 103 | |