Note 3 - Securities - Available-for-sale Debt Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Less than 12 months, number of securities	205	122
Less than 12 months, fair value	$ 240,563	$ 203,180
Less than 12 months, gross unrealized losses	$ 19,668	$ 3,904
12 months or longer, number of securities	192	12
12 months or longer, fair value	$ 225,813	$ 18,252
12 months or longer, gross unrealized losses	$ 42,249	$ 533
Total, number of securities	397	134
Total, fair value	$ 466,376	$ 221,432
Total, gross unrealized losses	$ 61,917	$ 4,437
US Treasury Securities [Member]
Less than 12 months, number of securities	0	16
Less than 12 months, fair value	$ 0	$ 35,394
Less than 12 months, gross unrealized losses	$ 0	$ 397
12 months or longer, number of securities	17	0
12 months or longer, fair value	$ 32,134	$ 0
12 months or longer, gross unrealized losses	$ 4,667	$ 0
Total, number of securities	17	16
Total, fair value	$ 32,134	$ 35,394
Total, gross unrealized losses	$ 4,667	$ 397
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months, number of securities	128	41
Less than 12 months, fair value	$ 146,932	$ 36,107
Less than 12 months, gross unrealized losses	$ 12,751	$ 702
12 months or longer, number of securities	94	2
12 months or longer, fair value	$ 69,872	$ 1,257
12 months or longer, gross unrealized losses	$ 16,801	$ 66
Total, number of securities	222	43
Total, fair value	$ 216,804	$ 37,364
Total, gross unrealized losses	$ 29,552	$ 768
Residential Mortgage-Backed Securities [Member]
Less than 12 months, number of securities	16	20
Less than 12 months, fair value	$ 26,826	$ 58,848
Less than 12 months, gross unrealized losses	$ 3,407	$ 1,530
12 months or longer, number of securities	26	2
12 months or longer, fair value	$ 53,581	$ 5,713
12 months or longer, gross unrealized losses	$ 9,763	$ 239
Total, number of securities	42	22
Total, fair value	$ 80,407	$ 64,561
Total, gross unrealized losses	$ 13,170	$ 1,769
Commercial Mortgage-Backed Securities [Member]
Less than 12 months, number of securities	2	1
Less than 12 months, fair value	$ 1,911	$ 1,632
Less than 12 months, gross unrealized losses	$ 94	$ 45
12 months or longer, number of securities	1	0
12 months or longer, fair value	$ 1,418	$ 0
12 months or longer, gross unrealized losses	$ 226	$ 0
Total, number of securities	3	1
Total, fair value	$ 3,329	$ 1,632
Total, gross unrealized losses	$ 320	$ 45
Collateralized Mortgage-Backed Securities [Member]
Less than 12 months, number of securities	7	6
Less than 12 months, fair value	$ 8,569	$ 14,585
Less than 12 months, gross unrealized losses	$ 219	$ 204
12 months or longer, number of securities	7	1
12 months or longer, fair value	$ 11,998	$ 1,596
12 months or longer, gross unrealized losses	$ 2,451	$ 20
Total, number of securities	14	7
Total, fair value	$ 20,567	$ 16,181
Total, gross unrealized losses	$ 2,670	$ 224
Mortgage-Backed Securities, Issued by Private Enterprises [Member]
Less than 12 months, number of securities	29	22
Less than 12 months, fair value	$ 27,705	$ 44,425
Less than 12 months, gross unrealized losses	$ 1,213	$ 897
12 months or longer, number of securities	28	3
12 months or longer, fair value	$ 42,819	$ 6,213
12 months or longer, gross unrealized losses	$ 6,928	$ 135
Total, number of securities	57	25
Total, fair value	$ 70,524	$ 50,638
Total, gross unrealized losses	$ 8,141	$ 1,032
Corporate Debt Securities [Member]
Less than 12 months, number of securities	18	9
Less than 12 months, fair value	$ 21,325	$ 7,643
Less than 12 months, gross unrealized losses	$ 1,805	$ 107
12 months or longer, number of securities	11	2
12 months or longer, fair value	$ 9,347	$ 2,180
12 months or longer, gross unrealized losses	$ 1,153	$ 70
Total, number of securities	29	11
Total, fair value	$ 30,672	$ 9,823
Total, gross unrealized losses	$ 2,958	$ 177
Asset-Backed Securities [Member]
Less than 12 months, number of securities	5	4
Less than 12 months, fair value	$ 7,295	$ 3,810
Less than 12 months, gross unrealized losses	$ 179	$ 14
12 months or longer, number of securities	5	2
12 months or longer, fair value	$ 3,988	$ 1,293
12 months or longer, gross unrealized losses	$ 172	$ 3
Total, number of securities	10	6
Total, fair value	$ 11,283	$ 5,103
Total, gross unrealized losses	$ 351	$ 17
Negotiable Certificates of Deposit [Member]
Less than 12 months, number of securities	0	3
Less than 12 months, fair value	$ 0	$ 736
Less than 12 months, gross unrealized losses	$ 0	$ 8
12 months or longer, number of securities	3	0
12 months or longer, fair value	$ 656	$ 0
12 months or longer, gross unrealized losses	$ 88	$ 0
Total, number of securities	3	3
Total, fair value	$ 656	$ 736
Total, gross unrealized losses	$ 88	$ 8