Note 4 - Investment Securities - Summary of Investment Securities with Unrealized Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Less than Twelve Months Estimated Fair Value, available for sale	$ 153,956	$ 121,563
Less than Twelve Months Unrealized Losses, available for sale	(637)	(5,116)
Twelve Months or More Estimated Fair Value, available for sale	175,389	118,611
Twelve Months or More Unrealized Losses	(36,460)	(26,145)
Total Estimated Fair Value, available for sale	329,345	240,174
Total Unrealized Losses, available for sale	(37,097)	(31,261)
Less than Twelve Months Estimated Fair Value, held to maturity	1,780	5,054
Less than Twelve Months Unrealized Losses, held to maturity	(137)	(173)
Twelve Months or More Estimated Fair Value, held to maturity	2,970	0
Twelve Months or More Unrealized Losses, held to maturity	(327)	0
Total Estimated Fair Value, held to maturity	4,750	5,054
Total Unrealized Losses, held to maturity	(464)	(173)
US Government Agencies Debt Securities [Member]
Less than Twelve Months Estimated Fair Value, available for sale	4,119	354
Less than Twelve Months Unrealized Losses, available for sale	(174)	(24)
Twelve Months or More Estimated Fair Value, available for sale	3,775	4,141
Twelve Months or More Unrealized Losses	(626)	(493)
Total Estimated Fair Value, available for sale	7,894	4,495
Total Unrealized Losses, available for sale	(800)	(517)
SBA Securities [Member]
Less than Twelve Months Estimated Fair Value, available for sale	0	2,411
Less than Twelve Months Unrealized Losses, available for sale	0	(223)
Twelve Months or More Estimated Fair Value, available for sale	2,115	0
Twelve Months or More Unrealized Losses	(272)	0
Total Estimated Fair Value, available for sale	2,115	2,411
Total Unrealized Losses, available for sale	(272)	(223)
Residential Mortgage-Backed Securities [Member]
Less than Twelve Months Estimated Fair Value, available for sale	0	5,535
Less than Twelve Months Unrealized Losses, available for sale	0	(362)
Twelve Months or More Estimated Fair Value, available for sale	33,437	32,522
Twelve Months or More Unrealized Losses	(8,064)	(6,390)
Total Estimated Fair Value, available for sale	33,437	38,057
Total Unrealized Losses, available for sale	(8,064)	(6,752)
Residential Collateralized Mortgage Obligations [Member]
Less than Twelve Months Estimated Fair Value, available for sale	11,956	27,050
Less than Twelve Months Unrealized Losses, available for sale	(310)	(1,842)
Twelve Months or More Estimated Fair Value, available for sale	59,243	39,815
Twelve Months or More Unrealized Losses	(14,834)	(11,014)
Total Estimated Fair Value, available for sale	71,199	66,865
Total Unrealized Losses, available for sale	(15,144)	(12,856)
Commercial Mortgage-Backed Securities [Member]
Less than Twelve Months Estimated Fair Value, available for sale		4,871
Less than Twelve Months Unrealized Losses, available for sale		(16)
Twelve Months or More Estimated Fair Value, available for sale		0
Twelve Months or More Unrealized Losses		0
Total Estimated Fair Value, available for sale		4,871
Total Unrealized Losses, available for sale		(16)
Commercial Collateralized Mortgage Obligations [Member]
Less than Twelve Months Estimated Fair Value, available for sale	23,696	18,741
Less than Twelve Months Unrealized Losses, available for sale	(121)	(790)
Twelve Months or More Estimated Fair Value, available for sale	38,800	22,949
Twelve Months or More Unrealized Losses	(3,222)	(2,111)
Total Estimated Fair Value, available for sale	62,496	41,690
Total Unrealized Losses, available for sale	(3,343)	(2,901)
Commercial Paper [Member]
Less than Twelve Months Estimated Fair Value, available for sale	114,185	39,624
Less than Twelve Months Unrealized Losses, available for sale	(32)	(16)
Twelve Months or More Estimated Fair Value, available for sale	0	0
Twelve Months or More Unrealized Losses	0	0
Total Estimated Fair Value, available for sale	114,185	39,624
Total Unrealized Losses, available for sale	(32)	(16)
Corporate Debt Securities [Member]
Less than Twelve Months Estimated Fair Value, available for sale	0	22,977
Less than Twelve Months Unrealized Losses, available for sale	0	(1,843)
Twelve Months or More Estimated Fair Value, available for sale	29,806	10,330
Twelve Months or More Unrealized Losses	(5,011)	(2,322)
Total Estimated Fair Value, available for sale	29,806	33,307
Total Unrealized Losses, available for sale	(5,011)	(4,165)
Municipal Bonds [Member]
Less than Twelve Months Estimated Fair Value, available for sale	0	0
Less than Twelve Months Unrealized Losses, available for sale	0	0
Twelve Months or More Estimated Fair Value, available for sale	8,213	8,854
Twelve Months or More Unrealized Losses	(4,431)	(3,815)
Total Estimated Fair Value, available for sale	8,213	8,854
Total Unrealized Losses, available for sale	(4,431)	(3,815)
Less than Twelve Months Estimated Fair Value, held to maturity	1,281	4,556
Less than Twelve Months Unrealized Losses, held to maturity	(134)	(170)
Twelve Months or More Estimated Fair Value, held to maturity	2,970	0
Twelve Months or More Unrealized Losses, held to maturity	(327)	0
Total Estimated Fair Value, held to maturity	4,251	4,556
Total Unrealized Losses, held to maturity	(461)	(170)
Taxable Municipal Bonds [Member]
Less than Twelve Months Estimated Fair Value, held to maturity	499	498
Less than Twelve Months Unrealized Losses, held to maturity	(3)	(3)
Twelve Months or More Estimated Fair Value, held to maturity	0	0
Twelve Months or More Unrealized Losses, held to maturity	0	0
Total Estimated Fair Value, held to maturity	499	498
Total Unrealized Losses, held to maturity	$ (3)	$ (3)