Note 2 - Securities - Available for Sale Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Total, fair value	$ 640,020	$ 510,918
Total, unrealized loss	73,561	7,258
Less than 12 months, fair value	285,215	456,863
Less than 12 months, unrealized loss	23,327	5,194
12 months or more, fair value	354,804	54,055
12 months or more, unrealized loss	50,234	2,064
US Treasury Securities [Member]
Total, fair value	138,537	149,577
Total, unrealized loss	13,572	1,174
Less than 12 months, fair value	48,059	149,577
Less than 12 months, unrealized loss	3,670	1,174
12 months or more, fair value	90,478	0
12 months or more, unrealized loss	9,902	0
US Government-sponsored Enterprises Debt Securities [Member]
Total, fair value	103,981	73,640
Total, unrealized loss	7,298	931
Less than 12 months, fair value	44,539	63,042
Less than 12 months, unrealized loss	2,898	512
12 months or more, fair value	59,442	10,598
12 months or more, unrealized loss	4,400	419
Collateralized Mortgage-Backed Securities [Member]
Total, fair value	305,858	253,444
Total, unrealized loss	43,640	4,525
Less than 12 months, fair value	124,623	213,292
Less than 12 months, unrealized loss	11,396	3,014
12 months or more, fair value	181,235	40,152
12 months or more, unrealized loss	32,244	1,511
US States and Political Subdivisions Debt Securities [Member]
Total, fair value	63,634	26,646
Total, unrealized loss	5,767	488
Less than 12 months, fair value	46,860	23,341
Less than 12 months, unrealized loss	2,953	354
12 months or more, fair value	16,774	3,305
12 months or more, unrealized loss	2,814	134
Corporate Debt Securities [Member]
Total, fair value	28,010	7,611
Total, unrealized loss	3,284	140
Less than 12 months, fair value	21,134	7,611
Less than 12 months, unrealized loss	2,410	140
12 months or more, fair value	6,875	0
12 months or more, unrealized loss	$ 874	$ 0