Note 4 - Securities - Securities in a Continuous Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Temporarily impaired securities, less than 12 months, fair value	$ 465,460	$ 266,414
Temporarily impaired securities, less than 12 months unrealized loss	57,475	4,922
Temporarily impaired securities, 12 months or more fair value	182,187	51,999
Temporarily impaired securities, 12 months or more unrealized loss	50,582	2,145
US Treasury Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	932
Temporarily impaired securities, less than 12 months unrealized loss	59
Temporarily impaired securities, 12 months or more fair value	0
Temporarily impaired securities, 12 months or more unrealized loss	0
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	207,506	201,650
Temporarily impaired securities, less than 12 months unrealized loss	25,296	3,530
Temporarily impaired securities, 12 months or more fair value	124,968	26,792
Temporarily impaired securities, 12 months or more unrealized loss	31,692	1,180
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	100,072	50,659
Temporarily impaired securities, less than 12 months unrealized loss	23,747	1,214
Temporarily impaired securities, 12 months or more fair value	43,622	20,542
Temporarily impaired securities, 12 months or more unrealized loss	17,482	793
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	152,201	13,139
Temporarily impaired securities, less than 12 months unrealized loss	7,624	141
Temporarily impaired securities, 12 months or more fair value	12,802	4,665
Temporarily impaired securities, 12 months or more unrealized loss	1,200	172
Corporate Debt Securities [Member]
Temporarily impaired securities, less than 12 months, fair value	4,749	966
Temporarily impaired securities, less than 12 months unrealized loss	749	37
Temporarily impaired securities, 12 months or more fair value	795	0
Temporarily impaired securities, 12 months or more unrealized loss	$ 208	$ 0