Note 5 - Debt Securities - Summary of Volume of State and Political Subdivision Securities Held in Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt securities, available for sale, amortized cost	$ 455,067	$ 398,643
Available for sale securities, unrealized gains	721	6,223
Available for sale securities, unrealized losses	50,587	3,763
Debt securities available for sale (at fair value)	405,201	$ 401,103
CALIFORNIA
Debt securities, available for sale, amortized cost	47,586
Available for sale securities, unrealized gains	0
Available for sale securities, unrealized losses	11,020
Debt securities available for sale (at fair value)	36,566
TEXAS
Debt securities, available for sale, amortized cost	38,457
Available for sale securities, unrealized gains	228
Available for sale securities, unrealized losses	5,089
Debt securities available for sale (at fair value)	33,596
MICHIGAN
Debt securities, available for sale, amortized cost	23,956
Available for sale securities, unrealized gains	55
Available for sale securities, unrealized losses	2,489
Debt securities available for sale (at fair value)	21,522
WASHINGTON
Debt securities, available for sale, amortized cost	20,655
Available for sale securities, unrealized gains	11
Available for sale securities, unrealized losses	1,784
Debt securities available for sale (at fair value)	18,882
OREGON
Debt securities, available for sale, amortized cost	15,760
Available for sale securities, unrealized gains	0
Available for sale securities, unrealized losses	4,173
Debt securities available for sale (at fair value)	$ 11,587