Note 8 - Investment Securities - Investments by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Due in one year or less, Amortized Cost	$ 350,165
Due in one year or less, Fair Value	348,984
Due after one year through five years, Amortized Cost	256,256
Due after one year through five years, Fair Value	241,910
Due after five years through ten years, Amortized Cost	169,294
Due after five years through ten years, Fair Value	160,169
Due after ten years, Amortized Cost	896,725
Due after ten years, Fair Value	790,187
Total, Amortized Cost	1,672,440	$ 1,622,173
Total, Fair Value	$ 1,541,250	$ 1,473,348