Note 9 - Investments in Marketable Securities (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Equity Securities Fv Ni Gross Unrealized Gain	$ 98,459,000		$ 84,514,000
Equity Securities Fv Ni Gross Unrealized Loss	474,000		928,000
Equity Securities, FV-NI, Unrealized Gain (Loss)	14,399,000	$ 1,386,000
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	179,000		326,000
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	8,273,000		$ 7,937,000
Proceeds from Sale and Maturity of Marketable Securities	11,615,000	15,492,000
Debt Securities, Realized Gain (Loss)	$ 344,000	$ (492,000)