Investment in Securities, Investment in Equity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments in Equity Securities [Abstract]
Cost	$ 42,397	$ 42,475
Estimated Fair Value	17,819	27,726
Common Stock [Member]
Investments in Equity Securities [Abstract]
Cost	41,148	41,226
Estimated Fair Value	16,729	26,463
Open-end Funds [Member]
Investments in Equity Securities [Abstract]
Cost	755	755
Estimated Fair Value	661	752
Closed-end Funds [Member]
Investments in Equity Securities [Abstract]
Cost	494	494
Estimated Fair Value	$ 429	$ 511