Note 2 - Securities - Available for Sale Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Total, fair value	$ 632,371	$ 510,918
Total, unrealized loss	33,807	7,258
Less than 12 months, fair value	541,499	456,863
Less than 12 months, unrealized loss	25,228	5,194
12 months or more, fair value	90,872	54,055
12 months or more, unrealized loss	8,579	2,064
US Treasury Securities [Member]
Total, fair value	144,835	149,577
Total, unrealized loss	7,425	1,174
Less than 12 months, fair value	144,835	149,577
Less than 12 months, unrealized loss	7,425	1,174
12 months or more, fair value	0	0
12 months or more, unrealized loss	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Total, fair value	91,878	73,640
Total, unrealized loss	3,432	931
Less than 12 months, fair value	66,968	63,042
Less than 12 months, unrealized loss	1,591	512
12 months or more, fair value	24,910	10,598
12 months or more, unrealized loss	1,841	419
Collateralized Mortgage-Backed Securities [Member]
Total, fair value	329,564	253,444
Total, unrealized loss	19,833	4,525
Less than 12 months, fair value	270,590	213,292
Less than 12 months, unrealized loss	13,849	3,014
12 months or more, fair value	58,974	40,152
12 months or more, unrealized loss	5,984	1,511
US States and Political Subdivisions Debt Securities [Member]
Total, fair value	45,065	26,646
Total, unrealized loss	2,396	488
Less than 12 months, fair value	38,077	23,341
Less than 12 months, unrealized loss	1,642	354
12 months or more, fair value	6,988	3,305
12 months or more, unrealized loss	754	134
Corporate Debt Securities [Member]
Total, fair value	21,029	7,611
Total, unrealized loss	721	140
Less than 12 months, fair value	21,029	7,611
Less than 12 months, unrealized loss	721	140
12 months or more, fair value	0	0
12 months or more, unrealized loss	$ 0	$ 0