Note 9 - Retirement Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Service cost including administrative expenses | $ 5,805 | $ 6,405 | $ 8,240 |
| Interest cost | 11,967 | 11,388 | 9,254 |
| Expected return on plan assets | (18,504) | (17,725) | (16,104) |
| Amortization of net loss | 750 | 220 | 0 |
| Amortization of prior service cost | 8 | 66 | 91 |
| Net periodic benefit cost | $ 26 | $ 354 | $ 1,481 |
| X | ||||||||||
- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan, including administration. No definition available.
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| X | ||||||||||
- Definition Amount of expense (reversal of expense) for net periodic benefit cost components, excluding settlement or curtailment expense. No definition available.
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| X | ||||||||||
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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| X | ||||||||||
- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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| X | ||||||||||
- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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| X | ||||||||||
- 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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