Note 2 - Securities - Debt Securities by Maturity (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Due in 2021, Weighted Average Yield	3.29%
Due in 2021, Amortized Cost	$ 881,000
Due in 2021, Fair Value	$ 886,000
Due in 2022 through 2026, Weighted Average Yield	1.06%
Due in 2022 through 2026, Amortized Cost	$ 172,553,000
Due in 2022 through 2026, Fair Value	$ 173,442,000
Due in 2027 through 2031, Weighted Average Yield	1.60%
Due in 2027 through 2031, Amortized Cost	$ 234,940,000
Due in 2027 through 2031, Fair Value	$ 235,320,000
Due in 2032 and beyond, Weighted Average Yield	2.03%
Due in 2032 and beyond, Amortized Cost	$ 58,542,000
Due in 2032 and beyond, Fair Value	$ 58,658,000
Total available for sale securities, Weighted Average Yield	1.49%
Total available for sale securities, Amortized Cost	$ 504,219,000	$ 380,403,000
Debt Securities, Available-for-sale, Total	$ 506,125,000	387,347,000
Collateralized Mortgage Backed Securities [Member]
No single maturity, weighted average yield	1.83%
No single maturity, amortized cost	$ 36,803,000
No single maturity, fair value	37,319,000
Total available for sale securities, Amortized Cost	36,803,000	23,869,000
Debt Securities, Available-for-sale, Total	$ 37,319,000	24,890,000
Other Debt and Equity Securities [Member]
No single maturity, weighted average yield	3.75%
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
Debt Securities, Available-for-sale, Total	$ 500,000	$ 500,000