Employees' Stock Option Plans (ESOP) - Schedule of Break-up of Employee Stock Compensation Expense (Details) - USD ($) $ in Millions |
12 Months Ended | ||||
|---|---|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
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| Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items] | |||||
| Employee stock compensation expense | $ 95 | $ 79 | $ 64 | ||
| Employee stock compensation expense | 2 | 2 | 1 | ||
| KMP | |||||
| Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items] | |||||
| Employee stock compensation expense | [1] | 8 | 8 | 6 | |
| Employees Other Than KMP | |||||
| Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Line Items] | |||||
| Employee stock compensation expense | $ 87 | $ 71 | $ 58 | ||
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