Investments (Available for sale equity investments) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Marketable Securities [Abstract]
Amortized cost, equity investments	$ 14,851	$ 17,574
Estimated market value, equity investments	25,125	24,168
Common stocks [Member]
Marketable Securities [Abstract]
Amortized cost, equity investments	9,775	10,123
Estimated market value, equity investments	20,015	17,379
Non-redeemable preferred stocks [Member]
Marketable Securities [Abstract]
Amortized cost, equity investments	5,076	7,451
Estimated market value, equity investments	$ 5,110	$ 6,789