Note 11 - Fair Values - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale, Total	$ 605,661,000	$ 592,743,000
Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-Sale, Total	0	0
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-Sale, Total	410,578,000	390,371,000
Collateralized Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Total	37,746,000	41,803,000
Municipal General Obligation Bonds [Member]
Debt Securities, Available-for-Sale, Total	134,671,000	137,594,000
Municipal Revenue Bonds [Member]
Debt Securities, Available-for-Sale, Total	22,166,000	22,475,000
Other Debt and Equity Securities [Member]
Debt Securities, Available-for-Sale, Total	500,000	500,000
Fair Value, Recurring [Member]
Total	615,714,000	597,352,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total	615,037,000	596,675,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total	677,000	677,000
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-Sale, Total	410,578,000	390,371,000
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-Sale, Total	410,578,000	390,371,000
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Total	37,746,000	41,803,000
Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-Sale, Total	37,746,000	41,803,000
Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Municipal General Obligation Bonds [Member]
Debt Securities, Available-for-Sale, Total	134,671,000	137,594,000
Fair Value, Recurring [Member] | Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-Sale, Total	133,994,000	136,917,000
Fair Value, Recurring [Member] | Municipal General Obligation Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-Sale, Total	677,000	677,000
Fair Value, Recurring [Member] | Municipal Revenue Bonds [Member]
Debt Securities, Available-for-Sale, Total	22,166,000	22,475,000
Fair Value, Recurring [Member] | Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-Sale, Total	22,166,000	22,475,000
Fair Value, Recurring [Member] | Municipal Revenue Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Other Debt and Equity Securities [Member]
Debt Securities, Available-for-Sale, Total	500,000	500,000
Fair Value, Recurring [Member] | Other Debt and Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Other Debt and Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Debt Securities, Available-for-Sale, Total	500,000	500,000
Fair Value, Recurring [Member] | Other Debt and Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-Sale, Total	0	0
Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Interest rate swaps	10,053,000	4,609,000
Fair Value, Recurring [Member] | Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Interest rate swaps	0	0
Fair Value, Recurring [Member] | Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Interest rate swaps	10,053,000	4,609,000
Fair Value, Recurring [Member] | Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Interest rate swaps	$ 0	$ 0