Note 5 - Loans and the Allowance for Credit Losses - Reversal of Accrued Interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Interest income reversed	$ 465,000	$ 147,000	$ 246,000
Commercial Portfolio Segment [Member] \| Commercial Loans [Member]
Interest income reversed	36,000	15,000	7,000
Commercial Portfolio Segment [Member] \| Agricultural Loans [Member]
Interest income reversed	381,000	29,000	153,000
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Interest income reversed	10,000	52,000	38,000
Residential Portfolio Segment [Member] \| Real Estate Loan [Member]
Interest income reversed	1,000	9,000	0
Residential Portfolio Segment [Member] \| Equity Lines of Credit [Member]
Interest income reversed	18,000	14,000	6,000
Consumer Portfolio Segment [Member] \| Automobile Loan [Member]
Interest income reversed	16,000	26,000	40,000
Consumer Portfolio Segment [Member] \| Other Loans [Member]
Interest income reversed	$ 3,000	$ 2,000	$ 2,000