Investments in Securities and Fair Value Investments in Securities (Schedule of Carrying Value and Fair Value of Financial Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financial Assets
Cash	$ 37,168	$ 13,723
Accrued interest and dividends	817	1,038
Common stocks	76,853	64,919
Money market funds	45,930	15,170
Equity investments in unconsolidated affiliates, measurement alternative	8,688	8,741
Assets, Fair Value Disclosure	169,456	103,591
Level 1
Financial Assets
Cash	37,168	13,723
Accrued interest and dividends	817	1,038
Common stocks	76,853	64,919
Money market funds	45,930	15,170
Equity investments in unconsolidated affiliates, measurement alternative	0	0
Assets, Fair Value Disclosure	160,768	94,850
Level 2
Financial Assets
Cash	0	0
Accrued interest and dividends	0	0
Common stocks	0	0
Money market funds	0	0
Equity investments in unconsolidated affiliates, measurement alternative	0	0
Assets, Fair Value Disclosure	0	0
Level 3
Financial Assets
Cash	0	0
Accrued interest and dividends	0	0
Common stocks	0	0
Money market funds	0	0
Equity investments in unconsolidated affiliates, measurement alternative	8,688	8,741
Assets, Fair Value Disclosure	$ 8,688	$ 8,741