Note 8 - Fair Value Measurements - Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Available-for-sale securities, at fair value	$ 334,446	$ 344,040
Fair Value, Recurring [Member]
Available-for-sale securities, at fair value	334,446	344,040
Total assets	334,581	344,211
Total liabilities	2,420	2,332
Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Interest rate swaps	135	171
Interest rate swaps	2,420	2,332
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, at fair value	0	0
Total assets	0	0
Total liabilities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Interest rate swaps	0	0
Interest rate swaps	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, at fair value	334,446	344,040
Total assets	334,581	344,211
Total liabilities	2,420	2,332
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Interest rate swaps	135	171
Interest rate swaps	2,420	2,332
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, at fair value	0	0
Total assets	0	0
Total liabilities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Interest rate swaps	0	0
Interest rate swaps	0	0
US Government Agencies Debt Securities [Member]
Available-for-sale securities, at fair value	28,571	27,545
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member]
Available-for-sale securities, at fair value	28,571	27,545
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, at fair value	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, at fair value	28,571	27,545
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, at fair value	0	0
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, at fair value	122,782	122,797
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member]
Available-for-sale securities, at fair value	122,782	122,797
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, at fair 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, at fair value	122,782	122,797
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, at fair value	0	0
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member]
Available-for-sale securities, at fair value	183,093	193,698
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] | Fair Value, Recurring [Member]
Available-for-sale securities, at fair value	183,093	193,698
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities, at fair value	0	0
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities, at fair value	183,093	193,698
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities, at fair value	$ 0	$ 0