Note 2 - Securities - Available for Sale Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Total, fair value	$ 584,935	$ 604,414
Total, unrealized loss	62,384	71,066
Less than 12 months, fair value	52,799	187,643
Less than 12 months, unrealized loss	1,471	13,616
12 months or more, fair value	532,136	416,771
12 months or more, unrealized loss	60,913	57,450
US Treasury Securities [Member]
Total, fair value	141,552	139,427
Total, unrealized loss	10,405	12,606
Less than 12 months, fair value	0	10,824
Less than 12 months, unrealized loss	0	915
12 months or more, fair value	141,552	128,603
12 months or more, unrealized loss	10,405	11,691
US Government-sponsored Enterprises Debt Securities [Member]
Total, fair value	83,941	82,958
Total, unrealized loss	5,664	7,019
Less than 12 months, fair value	15,187	29,204
Less than 12 months, unrealized loss	346	1,920
12 months or more, fair value	68,754	53,754
12 months or more, unrealized loss	5,318	5,099
Collateralized Mortgage-Backed Securities [Member]
Total, fair value	285,938	293,929
Total, unrealized loss	38,201	42,301
Less than 12 months, fair value	22,631	96,758
Less than 12 months, unrealized loss	596	7,245
12 months or more, fair value	263,307	197,171
12 months or more, unrealized loss	37,605	35,056
US States and Political Subdivisions Debt Securities [Member]
Total, fair value	46,062	60,629
Total, unrealized loss	4,255	5,312
Less than 12 months, fair value	9,841	31,866
Less than 12 months, unrealized loss	118	980
12 months or more, fair value	36,221	28,763
12 months or more, unrealized loss	4,137	4,332
Corporate Debt Securities [Member]
Total, fair value	27,442	27,471
Total, unrealized loss	3,859	3,828
Less than 12 months, fair value	5,140	18,991
Less than 12 months, unrealized loss	411	2,556
12 months or more, fair value	22,302	8,480
12 months or more, unrealized loss	$ 3,448	$ 1,272