Note 4 - Investment Securities - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Available for sale, amortized cost	$ 391,474	$ 288,088
Available for sale, gross unrealized gains	1	3
Available for sale, gross unrealized losses	(37,097)	(31,261)
Available for sale	354,378	256,830
Held to maturity (fair value of $4,750 and $5,563 at September 30, 2023 and December 31, 2022, respectively)	5,214	5,729
Held to maturity, gross unrealized gains	0	7
Held to maturity, gross unrealized losses	(464)	(173)
Securities held to maturity, fair value	4,750	5,563
US Government Agencies Debt Securities [Member]
Available for sale, amortized cost	8,694	5,012
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(800)	(517)
Available for sale	7,894	4,495
Small Business Administration Agency Securities [Member]
Available for sale, amortized cost	7,533	2,634
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(272)	(223)
Available for sale	7,261	2,411
Residential Mortgage-Backed Securities [Member]
Available for sale, amortized cost	41,501	44,809
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(8,064)	(6,752)
Available for sale	33,437	38,057
Residential Collateralized Mortgage Obligations [Member]
Available for sale, amortized cost	86,343	82,759
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(15,144)	(12,856)
Available for sale	71,199	69,903
Commercial Mortgage-Backed Securities [Member]
Available for sale, amortized cost		4,887
Available for sale, gross unrealized gains		0
Available for sale, gross unrealized losses		(16)
Available for sale		4,871
Commercial Collateralized Mortgage Obligations [Member]
Available for sale, amortized cost	70,837	44,591
Available for sale, gross unrealized gains	1	0
Available for sale, gross unrealized losses	(3,343)	(2,901)
Available for sale	67,495	41,690
Commercial Paper [Member]
Available for sale, amortized cost	129,105	49,551
Available for sale, gross unrealized gains	0	2
Available for sale, gross unrealized losses	(32)	(16)
Available for sale	129,073	49,537
Corporate Debt Securities [Member]
Available for sale, amortized cost	34,817	41,176
Available for sale, gross unrealized gains	0	1
Available for sale, gross unrealized losses	(5,011)	(4,165)
Available for sale	29,806	37,012
Municipal Bonds [Member]
Available for sale, amortized cost	12,644	12,669
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	(4,431)	(3,815)
Available for sale	8,213	8,854
Held to maturity (fair value of $4,750 and $5,563 at September 30, 2023 and December 31, 2022, respectively)	4,712	4,726
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	(461)	(170)
Securities held to maturity, fair value	4,251	4,556
Taxable Municipal Bonds [Member]
Held to maturity (fair value of $4,750 and $5,563 at September 30, 2023 and December 31, 2022, respectively)	502	1,003
Held to maturity, gross unrealized gains	0	7
Held to maturity, gross unrealized losses	(3)	(3)
Securities held to maturity, fair value	$ 499	$ 1,007