Note 8 - Related Party Transactions (Details Textual) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2023		Sep. 30, 2023	[1]	Jun. 30, 2023	[1]	Mar. 31, 2023	[1]	Dec. 31, 2022		Sep. 30, 2022	[1]	Jun. 30, 2022	[1]	Mar. 31, 2022	[1]	Dec. 31, 2023	Dec. 31, 2022
Investment Income, Net																	$ 1,566	$ 413
Gain (Loss) on Investments	$ 0	[1]	$ (4)		$ 43		$ 345		$ (298)	[1]	$ (2,121)		$ (2,373)		$ 45		384	(4,747)
Income Taxes Paid																	$ 207	$ 741
GAMCO Investors, Inc. [Member]
Investment Expense Rate																	0.17%	0.52%
Funds Invested in Mutual Funds	32,568								26,811								$ 32,568	$ 26,811
Income From Mutual Funds																	1,677
Investment Income, Net																	1,307
Gain (Loss) on Investments																	370
GAMCO Investors, Inc. [Member] | Cash and Cash Equivalents [Member]
Funds Invested in Mutual Funds									10,295									10,295
GAMCO Investors, Inc. [Member] | Marketable Securities [Member]
Funds Invested in Mutual Funds									$ 16,516									16,516
MtronPTI [Member]
Excess Separation Costs																	28	219
MtronPTI [Member] | Transitional Administrative and Management Services Agreement [Member]
Monthly Payment	$ 4																4
MtronPTI [Member] | Tax Indemnity and Sharing Agreement [Member]
Income Taxes Paid																	$ 0	$ 0

[1] During Q1 and Q2 2023, the net gains primarily relate to the sale of our investments in mutual funds managed by GAMCO Investors, Inc.