Employee Benefit Plans - Schedule of Change in Benefit Obligation (Details) - Other Postretirement Benefits Plan - Officer Medical Plan - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
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| Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] | |||
| Benefit obligation, beginning of the year | $ 174 | $ 127 | $ 106 |
| Service cost | 7 | 6 | 5 |
| Interest cost | 10 | 6 | 5 |
| Net actuarial (gain) loss | (3) | 41 | 17 |
| Benefits paid | (6) | (6) | (6) |
| Gain due to curtailment | (2) | 0 | 0 |
| Benefit obligation, end of the year | $ 180 | $ 174 | $ 127 |
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- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
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- Definition Amount of (increase) decrease in benefit obligation of defined benefit plan from event reducing expected years of future service of present employees or eliminating accrual of benefits for some or all future services of present employees. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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