Employee Benefits - Employee Benefit Costs (Parenthetical) (Details) - USD ($) $ in Millions |
12 Months Ended | ||||
|---|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
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| Disclosure of defined benefit plans [abstract] | |||||
| Stock compensation expense | [1] | $ 108 | $ 95 | $ 79 | |
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