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Income Taxes - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Jun. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Income Tax Contingency [Line Items] |  |  |  |  |
Tax expense (benefit), intra-entity transfers of assets other than inventory, amount | $ (44) |  | $ (147) |  |
Canadian businesses held for sale |  |  |  | $ 638 | $ 0
Effective income tax rate reconciliation, foreign income tax rate differential, expense (benefit) |  |  |  | (58) |
Tax expense (benefit), share-based payment arrangement |  |  |  | (38) |
Unrecognized tax benefits, increase (decrease) |  |  |  | (47) |
Tax contingency, interest expense, amount |  | $ 12 |  | 37 |
Unrecognized tax benefits | 1,400 |  |  | 1,400 |
Unrecognized tax benefits that would impact effective tax rate | 1,300 |  |  | 1,300 |
Held-for-sale | Canadian retail disposal group |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Canadian businesses held for sale | $ 643 |  |  | $ 643 |

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