Note 4 - Marketable Equity Securities (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Investment Income, Dividend	$ 1,557,000	$ 1,539,000	$ 1,448,000
Equity Securities, FV-NI, Total	8,099,000	7,875,000
Equity Securities, FV-NI, Unrealized Loss	2,630,000	$ 2,100,000
Margin Account Borrowings [Member]
Debt, Weighted Average Interest Rate		4.92%
Margin Account Borrowings [Member] | Accrued Expenses And Other Liabilities And Other Long-term Liabilities [Member]
Short-Term Debt, Total	$ 0	$ 914,000