Note 3 - Investment Securities - Investment Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	$ 73,636	$ 216,613
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	(2,128)	(13,095)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	229,929	119,513
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	(30,350)	(22,765)
US Government Agencies Debt Securities [Member]
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	798	1,773
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	(92)	(187)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	946	0
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	(113)	0
US Treasury and Government [Member]
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	0	10,969
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	0	(196)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	46,058	40,982
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	(6,404)	(6,568)
US States and Political Subdivisions Debt Securities [Member]
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	39,143	128,036
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	(848)	(8,781)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	86,487	33,092
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	(13,017)	(9,258)
Corporate Debt Securities [Member]
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	1,118	4,994
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	(132)	(246)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	2,713	995
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	(279)	(5)
Mortgage-backed Securities and Collateralized Mortgage Obligations [Member]
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	23,173	67,310
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	(951)	(3,647)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	93,725	44,444
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	(10,537)	(6,934)
Asset-Backed Securities [Member]
Available for sale debt securities, continuous unrealized loss position less than 12 months, fair value	9,404	3,531
Available for sale debt securities, continuous unrealized loss position less than 12 months, gross unrealized losses	(105)	(38)
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, fair value	0	0
Available for sale debt securities, continuous unrealized loss position for 12 months or longer, gross unrealized losses	$ 0	$ 0