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Income Taxes - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2025 | Sep. 30, 2024 | Mar. 31, 2024 | Jun. 30, 2023 | Mar. 31, 2025 | Mar. 31, 2024 | Mar. 31, 2023 | Mar. 31, 2022
Income Tax Contingency [Line Items] |  |  |  |  |  |  |  |
Net tax benefit on intellectual property repatriation and sales |  |  |  |  | $ (258) | $ (104) | $ 0 |
Tax expense (benefit), intra-entity transfers of assets other than inventory, amount | $ (214) | $ (44) | $ (43) | $ (147) |  |  |  |
Effective income tax rate reconciliation, release of valuation allowance |  |  |  |  | 0 | (157) | 0 |
Discrete tax benefits related to statute of limitation expirations and tax settlements |  |  |  |  |  |  | 115 |
Tax expense (benefit), share-based payment arrangement |  |  |  |  | (42) | (37) | (58) |
Valuation allowance | 644 |  | 653 |  | 644 | 653 |  |
Unrecognized tax benefits | 1,532 |  | 1,463 |  | 1,532 | 1,463 | 1,399 | $ 1,523
Unrecognized tax benefits that would Impact income tax expense and the effective tax rate | 1,400 |  |  |  | 1,400 |  |  |
Income tax expense (benefit), before any tax effect, related to accrued interest and penalties |  |  |  |  | 80 | 84 | $ 31 |
Accrued interest and penalties on unrecognized tax benefits | 302 |  | $ 222 |  | 302 | $ 222 |  |
Undistributed earnings of foreign operations | 4,000 |  |  |  | 4,000 |  |  |
Minimum |  |  |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |  |  |
Tax liability increase due to proposed adjustment to taxable income | 600 |  |  |  | 600 |  |  |
Maximum |  |  |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |  |  |
Tax liability increase due to proposed adjustment to taxable income | 700 |  |  |  | 700 |  |  |
Federal |  |  |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |  |  |
Federal, state and foreign net operating loss carryforwards | 40 |  |  |  | 40 |  |  |
State |  |  |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |  |  |
Federal, state and foreign net operating loss carryforwards | 4,100 |  |  |  | 4,100 |  |  |
Capital Loss Carryforward | Foreign Tax Jurisdiction |  |  |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |  |  |
Federal, state and foreign net operating loss carryforwards | $ 1,300 |  |  |  | $ 1,300 |  |  |

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