Note 2 - Securities - Debt Securities by Maturity (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Due in 2023, Weighted Average Yield	0.35%
Due in 2023, Amortized Cost	$ 10,635,000
Due in 2023, Fair Value	$ 10,560,000
Due in 2024 through 2028, Weighted Average Yield	1.32%
Due in 2024 through 2028, Amortized Cost	$ 319,456,000
Due in 2024 through 2028, Fair Value	$ 289,600,000
Due in 2029 through 2033, Weighted Average Yield	2.02%
Due in 2029 through 2033, Amortized Cost	$ 278,377,000
Due in 2029 through 2033, Fair Value	$ 227,860,000
Due in 2034 and beyond, Weighted Average Yield	3.68%
Due in 2034 and beyond, Amortized Cost	$ 40,788,000
Due in 2034 and beyond, Fair Value	$ 35,769,000
Total available for sale securities, weighted average yield	1.78%
Total available for sale securities, Amortized Cost	$ 685,455,000	$ 685,646,000
Securities available for sale	$ 592,305,000	602,936,000
Collateralized Mortgage-Backed Securities [Member]
No single maturity, weighted average yield	2.18%
No single maturity, amortized cost	$ 35,699,000
No single maturity, fair value	28,016,000
Total available for sale securities, Amortized Cost	35,699,000	38,002,000
Securities available for sale	$ 28,016,000	31,953,000
Other Debt and Equity Securities [Member]
No single maturity, weighted average yield	8.42%
No single maturity, amortized cost	$ 500,000
No single maturity, fair value	500,000
Total available for sale securities, Amortized Cost	500,000	500,000
Securities available for sale	$ 500,000	$ 500,000