Investments (Available for sale equity investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Marketable Securities [Abstract]
Amortized cost, equity investments	$ 17,574	$ 17,574
Estimated market value, equity investments	26,663	24,168
Common stocks [Member]
Marketable Securities [Abstract]
Amortized cost, equity investments	10,123	10,123
Estimated market value, equity investments	19,207	17,379
Non-redeemable preferred stocks [Member]
Marketable Securities [Abstract]
Amortized cost, equity investments	7,451	7,451
Estimated market value, equity investments	$ 7,456	$ 6,789