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Debt and Financing Activities - Long-Term Debt Narrative (Details) - USD ($) $ in Millions |  |  |  | 6 Months Ended |
--- | --- | --- | --- | --- | ---
Sep. 10, 2024 | Jun. 16, 2023 | Jun. 15, 2023 | Sep. 30, 2024 | Sep. 30, 2023 | Mar. 31, 2024
Debt Instrument [Line Items] |  |  |  |  |  |
Long-term debt |  |  |  | $ 5,700 |  | $ 5,600
Current portion of long-term debt |  |  |  | 53 |  | $ 50
Repayments of long-term debt |  |  |  | 501 | $ 271 |
Purchase of U.S. government obligations for the satisfaction and discharge of long-term debt |  |  |  | $ 0 | 647 |
Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Redemption price percentage of principal (percent) |  |  | 101.00% |  |  |
Term Loan | Minimum |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt instrument, redemption period (in days) |  |  | 10 days |  |  |
Term Loan | Maximum |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt instrument, redemption period (in days) |  |  | 60 days |  |  |
4.25% Notes due September 15, 2029 | Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate on debt instrument (percent) | 4.25% |  |  | 4.25% |  |
Debt principal amount | $ 500 |  |  |  |  |
Proceeds from debt issuance | $ 496 |  |  |  |  |
5.25% Notes due February 15, 2026 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate on debt instrument (percent) | 5.25% |  |  |  |  |
5.25% Notes due February 15, 2026 | Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate on debt instrument (percent) |  |  |  | 5.25% |  |
Redemption price percentage of principal (percent) | 100.00% |  |  |  |  |
Repayments of long-term debt | $ 500 |  |  |  |  |
4.90% Notes due July 15, 2028 | Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate on debt instrument (percent) |  |  | 4.90% | 4.90% |  |
Debt principal amount |  |  | $ 400 |  |  |
Proceeds from debt issuance |  |  | $ 397 |  |  |
5.10% Notes due July 15, 2033 | Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate on debt instrument (percent) |  |  | 5.10% | 5.10% |  |
Debt principal amount |  |  | $ 600 |  |  |
Proceeds from debt issuance |  |  | $ 592 |  |  |
3.80% Notes due March 15, 2024 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate on debt instrument (percent) |  |  | 3.80% |  |  |
3.80% Notes due March 15, 2024 | Term Loan |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Redemption price percentage of principal (percent) |  | 98.75% |  |  |  |
Repayments of long-term debt |  | $ 268 |  |  |  |
Debt principal redeemed |  | 271 |  |  |  |
Purchase of U.S. government obligations for the satisfaction and discharge of long-term debt |  | $ 647 |  |  |  |
Gain on debt extinguishment |  |  |  |  | $ 9 |

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