Note 3 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Temporarily impaired securities, less than 12 months, fair value	$ 389,208	$ 266,414
Temporarily impaired securities, less than 12 months unrealized loss	39,109	4,922
Temporarily impaired securities, 12 months or more fair value	259,070	51,999
Temporarily impaired securities, 12 months or more unrealized loss	64,043	2,145
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	144,574	201,650
Temporarily impaired securities, less than 12 months unrealized loss	12,699	3,530
Temporarily impaired securities, 12 months or more fair value	190,950	26,792
Temporarily impaired securities, 12 months or more unrealized loss	42,303	1,180
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	94,657
Temporarily impaired securities, less than 12 months unrealized loss	18,373
Temporarily impaired securities, 12 months or more fair value	52,134
Temporarily impaired securities, 12 months or more unrealized loss	19,645
US Treasury Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	936	50,659
Temporarily impaired securities, less than 12 months unrealized loss	56	1,214
Temporarily impaired securities, 12 months or more fair value	0	20,542
Temporarily impaired securities, 12 months or more unrealized loss	0	793
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	144,198	13,139
Temporarily impaired securities, less than 12 months unrealized loss	7,326	141
Temporarily impaired securities, 12 months or more fair value	15,165	4,665
Temporarily impaired securities, 12 months or more unrealized loss	1,913	172
Corporate Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	4,843	966
Temporarily impaired securities, less than 12 months unrealized loss	655	37
Temporarily impaired securities, 12 months or more fair value	821	0
Temporarily impaired securities, 12 months or more unrealized loss	$ 182	$ 0