Investments - Schedule of Amounts Recorded in Other Comprehensive Income (Details) - USD ($) $ in Millions |
12 Months Ended | ||||
|---|---|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
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| Disclosure Of Analysis Of Other Comprehensive Income By Item [Line Items] | |||||
| Other comprehensive income, Net | [1] | $ 24 | $ 17 | $ (30) | |
| Quoted Debt Securities | |||||
| Disclosure Of Analysis Of Other Comprehensive Income By Item [Line Items] | |||||
| Other comprehensive income, Gross | 26 | 19 | (31) | ||
| Other comprehensive income, Tax | (3) | (2) | 1 | ||
| Other comprehensive income, Net | 23 | 17 | (30) | ||
| Certificates of Deposit and Commercial Papers | |||||
| Disclosure Of Analysis Of Other Comprehensive Income By Item [Line Items] | |||||
| Other comprehensive income, Gross | 1 | ||||
| Other comprehensive income, Net | 1 | ||||
| Equity And Preference Securities | |||||
| Disclosure Of Analysis Of Other Comprehensive Income By Item [Line Items] | |||||
| Other comprehensive income, Gross | 2 | 1 | (3) | ||
| Other comprehensive income, Tax | 1 | ||||
| Other comprehensive income, Net | $ 2 | $ 2 | $ (3) | ||
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