Investments (Available for sale equity investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024
Debt Securities Trading And Equity Securities FvNi Cost [Abstract]
Amortized cost, equity investments	$ 60,428	$ 54,748
Estimated market value, equity investments	74,066	66,274
Common Stock [Member]
Debt Securities Trading And Equity Securities FvNi Cost [Abstract]
Amortized cost, equity investments	35,284	29,604
Estimated market value, equity investments	51,999	45,014
Nonredeemable Preferred Stock [Member]
Debt Securities Trading And Equity Securities FvNi Cost [Abstract]
Amortized cost, equity investments	25,144	25,144
Estimated market value, equity investments	$ 22,067	$ 21,260