Note 5 - Investments (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)
Investment Owned, Fair Value	$ 22	$ 16,585
Proceeds from Sale and Maturity of Marketable Securities	16,947	2,058
Marketable Security, Realized Gain (Loss)	$ (4,316)	$ (22,868)
Iron Net [Member] | Discontinued Operations, Disposed of by Sale [Member]
Investment Owned, Balance, Shares (in shares) | shares	198,250
GAMCO Investors, Inc. [Member] | Discontinued Operations, Disposed of by Sale [Member]
Proceeds from Sale and Maturity of Marketable Securities	$ 16,886
Marketable Security, Realized Gain (Loss)	$ 370
GAMCO Investors, Inc. [Member]
Number of Mutual Fund Investments	0	2
Iron Net [Member]
Investment Owned, Cost	$ 46
Investment Owned, Fair Value	$ 4,273