Note 3 - Securities - Securities Reconciliation (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available-for-sale securities, amortized costs	$ 513,424	$ 436,249
Available-for-sale securities, gross unrealized gain	8,502	10,933
Available-for-sale securities, gross unrealized loss	(4,551)	(302)
Debt Securities, Available-for-sale	517,375	446,880
US Government Agencies Debt Securities [Member]
Available-for-sale securities, amortized costs	30,460	32,164
Available-for-sale securities, gross unrealized gain	696	838
Available-for-sale securities, gross unrealized loss	(96)	(8)
Debt Securities, Available-for-sale	31,060	32,994
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, amortized costs	127,136	103,424
Available-for-sale securities, gross unrealized gain	3,361	4,971
Available-for-sale securities, gross unrealized loss	(1,657)	(29)
Debt Securities, Available-for-sale	128,840	108,366
Residential Mortgage Backed Securities and Collateralized Mortgage Obligations [Member]
Available-for-sale securities, amortized costs	276,782	236,829
Available-for-sale securities, gross unrealized gain	3,127	3,895
Available-for-sale securities, gross unrealized loss	(2,362)	(246)
Debt Securities, Available-for-sale	277,547	240,478
Commercial Mortgage Backed Securities [Member]
Available-for-sale securities, amortized costs	38,538	27,455
Available-for-sale securities, gross unrealized gain	481	637
Available-for-sale securities, gross unrealized loss	(436)	(18)
Debt Securities, Available-for-sale	38,583	28,074
Asset-backed Securities [Member]
Available-for-sale securities, amortized costs	40,508	36,377
Available-for-sale securities, gross unrealized gain	837	592
Available-for-sale securities, gross unrealized loss	0	(1)
Debt Securities, Available-for-sale	$ 41,345	$ 36,968