Note 6 - Investments and Equity Securities (Details Textual)		12 Months Ended
		Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Proceeds from Sale and Maturity of Marketable Securities		$ 0	$ 57,887,000
Realized Investment Gains (Losses)		$ 0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions		9
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions		167
Debt Securities, Available-for-Sale, Allowance for Credit Loss		$ 0
Other-than-temporary Impairment Loss, Debt Securities, Available-for-Sale 1		0
Equity Securities, FV-NI, Current		955,000	915,000
Equity Securities, FV-NI, Unrealized Gain (Loss)	[1]	(161,000)	(173,000)
Equity Securities, FV-NI, Realized Gain (Loss)		0	0
Asset Pledged as Collateral [Member] | Deposits [Member]
Financial Instruments, Owned, at Fair Value		$ 118,800,000	$ 89,900,000

[1] Not within scope of ASC 606