Note 8 - Fair Value - Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Securities available for sale, at fair value	$ 121,434	$ 125,713
Fair value, held to maturity	19,882
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	31,283	64,659
Equity security	535	518
Noninterest-bearing deposits	121,398	107,197
Securities sold under repurchase agreements	4,772	5,564
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Certificates of deposit in other banks	100	100
Accrued interest receivable	2,388	2,439
Securities available for sale, at fair value	121,434	125,713
Fair value, held to maturity	17,292	17,156
Mortgage loans held for sale	641	157
Restricted stock, at cost	1,190	921
Bank owned life insurance	15,535	15,324
Fair value hedge	114	626
Interest-bearing deposits	627,500	651,609
Federal Home Loan Bank advances	10,000	5,000
Long-term debt, net	10,388	11,329
Accrued interest payable	919	1,003
Fair value hedge	233	28
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value, held to maturity	4,036	3,343
Loans, net	615,469	582,993
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	31,283	64,659
Equity security	535	518
Noninterest-bearing deposits	121,398	107,197
Securities sold under repurchase agreements	4,772	5,564
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Certificates of deposit in other banks	100	100
Accrued interest receivable	2,388	2,439
Securities available for sale, at fair value	121,434	125,713
Fair value, held to maturity	15,846	15,589
Mortgage loans held for sale	641	157
Restricted stock, at cost	1,190	921
Bank owned life insurance	15,535	15,324
Fair value hedge	114	626
Interest-bearing deposits	630,136	654,346
Federal Home Loan Bank advances	9,811	4,957
Long-term debt, net	10,297	11,066
Accrued interest payable	919	1,003
Fair value hedge	233	28
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value, held to maturity	4,036	3,343
Loans, net	$ 610,730	$ 572,346

Farmers & Merchants Bancshares, Inc. 10-Q