Investments (Available for sale equity investments) (Details) - USD ($) $ in Thousands |
Sep. 30, 2025 |
Mar. 31, 2025 |
|---|---|---|
| Debt Securities Trading And Equity Securities FvNi Cost [Abstract] | ||
| Amortized cost, equity investments | $ 52,041 | $ 55,252 |
| Estimated market value, equity investments | 62,972 | 65,549 |
| Common Stock [Member] | ||
| Debt Securities Trading And Equity Securities FvNi Cost [Abstract] | ||
| Amortized cost, equity investments | 32,938 | 30,108 |
| Estimated market value, equity investments | 47,289 | 43,413 |
| Nonredeemable Preferred Stock [Member] | ||
| Debt Securities Trading And Equity Securities FvNi Cost [Abstract] | ||
| Amortized cost, equity investments | 19,103 | 25,144 |
| Estimated market value, equity investments | $ 15,683 | $ 22,136 |