Note 7 - Related Party Transactions - Transactions With Related Parties (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Income	$ 888	$ 984
Expense	(809)	(734)
Assets	41,951		$ 41,850
Liabilities	1,217		1,168
GAMCO Investors, Inc. [Member]
Income	408	434
Expense	0	0
Assets	32,977		32,568
Liabilities	0		0
Mtron Industries Inc [Member]
Income	0	0
Expense	(14)	(16)
Assets	5		0
Liabilities	0		0
Related Party [Member]
Income	408	434
Expense	(14)	$ (16)
Assets	32,982		32,568
Liabilities	$ 0		$ 0