Note 4 - Investments - Fair Value of Financial Instruments Measured on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Total Investments	$ 5,368	$ 5,564
Fair Value, Inputs, Level 1 [Member]
Total Investments	0	0
Fair Value, Inputs, Level 2 [Member]
Total Investments	0	0
Fair Value, Inputs, Level 3 [Member]
Total Investments	1,250	1,250
Common Stock [Member]
Total Investments	250	250
Common Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Total Investments	0	0
Common Stock [Member] | Fair Value, Inputs, Level 2 [Member]
Total Investments	0	0
Common Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Total Investments	250	250
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Total Investments	1,000	1,000
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Fair Value, Inputs, Level 1 [Member]
Total Investments	0	0
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Fair Value, Inputs, Level 2 [Member]
Total Investments	0	0
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Fair Value, Inputs, Level 3 [Member]
Total Investments	1,000	1,000
Investments, at Fair Value [Member]
Total Investments	1,250	1,250
Investments, at Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
Total Investments	0	0
Investments, at Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
Total Investments	0	0
Investments, at Fair Value [Member] | Fair Value, Inputs, Level 3 [Member]
Total Investments	1,250	1,250
US Government Agencies Debt Securities [Member]
Total Investments	4,118	4,314
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total Investments	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total Investments	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total Investments	$ 0	$ 0