Note 5 - Financial Instruments and Fair Value Measurements - Schedule of Recurring and Non-recurring Assets and Liabilities (Details) - USD ($)	Mar. 31, 2026	Dec. 31, 2025
Available-for-sale securities, fair market value	$ 555,047,000	$ 543,532,000
Mutual fund	3,434,000	3,424,000
Fair Value, Nonrecurring [Member] \| Collateral Pledged [Member]
Collateral dependent loans	2,847,000	3,298,000
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Collateral Pledged [Member]
Collateral dependent loans	0	0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Collateral Pledged [Member]
Collateral dependent loans	0	0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Collateral Pledged [Member]
Collateral dependent loans	2,847,000	3,298,000
US Government Agencies Debt Securities [Member]
Available-for-sale securities, fair market value	113,792,000	101,537,000
US Government Agencies Debt Securities [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities, fair market value	113,792,000	101,537,000
US Government Agencies Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, fair market value	0	0
US Government Agencies Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, fair market value	113,792,000	101,537,000
US Government Agencies Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, fair market value	0	0
Collateralized Mortgage Obligations [Member]
Available-for-sale securities, fair market value	36,522,000	34,793,000
Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities, fair market value	36,522,000	34,793,000
Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, fair market value	0	0
Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, fair market value	36,522,000	34,793,000
Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, fair market value	0	0
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, fair market value	342,738,000	338,468,000
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities, fair market value	342,738,000	338,468,000
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, fair market value	0	0
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, fair market value	342,738,000	338,468,000
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, fair market value	0	0
SBA Pool [Member]
Available-for-sale securities, fair market value	524,000	559,000
SBA Pool [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities, fair market value	524,000	559,000
SBA Pool [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, fair market value	0	0
SBA Pool [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, fair market value	524,000	559,000
SBA Pool [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, fair market value	0	0
Corporate Debt Securities [Member]
Available-for-sale securities, fair market value	35,324,000	40,412,000
Corporate Debt Securities [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities, fair market value	35,324,000	40,412,000
Corporate Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, fair market value	0	0
Corporate Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, fair market value	35,324,000	40,412,000
Corporate Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, fair market value	0	0
Asset-Backed Securities [Member]
Available-for-sale securities, fair market value	26,147,000	27,763,000
Asset-Backed Securities [Member] \| Fair Value, Recurring [Member]
Available-for-sale securities, fair market value	26,147,000	27,763,000
Asset-Backed Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, fair market value	0	0
Asset-Backed Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, fair market value	26,147,000	27,763,000
Asset-Backed Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, fair market value	0	0
Mutual Fund [Member] \| Fair Value, Recurring [Member]
Mutual fund	3,434,000	3,424,000
Mutual Fund [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Mutual fund	3,434,000	3,424,000
Mutual Fund [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Mutual fund	0	0
Mutual Fund [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Mutual fund	$ 0	$ 0