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Note 2 - Securities - Summary of Amortized Costs and Fair Values of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Amortized cost, available for sale securities	$ 265,463	$ 136,355
Gross unrealized gains, available for sale securities	2,787	3,952
Gross unrealized losses, available for sale securities	(1,650)	(82)
Fair value, available for sale securities	266,600	140,225	[1]
Securities held to maturity, at amortized cost (fair value, 2021, $10,262; 2020, $14,743)	10,046	14,234	[1]
Gross unrealized gains, held to maturity securities	218	509
Gross unrealized losses, held to maturity securities	(2)	0
Securities, fair value	10,262	14,743	[1]
Amortized cost, held to maturity securities	10,046	14,234	[1]
Fair value, held to maturity securities	10,262	14,743	[1]
Amortized cost	275,509	150,589
Gross unrealized gains	3,005	4,461
Gross unrealized losses	(1,652)	(82)
Total securities, fair value	276,862	154,968
US Treasury Securities [Member]
Amortized cost, available for sale securities	19,951
Gross unrealized gains, available for sale securities	63
Gross unrealized losses, available for sale securities	(38)
Fair value, available for sale securities	19,976
US Agency and Mortgage-backed Securities [Member]
Amortized cost, available for sale securities	172,782	98,848
Gross unrealized gains, available for sale securities	1,713	2,830
Gross unrealized losses, available for sale securities	(1,234)	(80)
Fair value, available for sale securities	173,261	101,598
Securities held to maturity, at amortized cost (fair value, 2021, $10,262; 2020, $14,743)	7,301	9,588
Gross unrealized gains, held to maturity securities	117	264
Gross unrealized losses, held to maturity securities	(2)	0
Securities, fair value	7,416	9,852
Amortized cost, held to maturity securities	7,301	9,588
Fair value, held to maturity securities	7,416	9,852
US States and Political Subdivisions Debt Securities [Member]
Amortized cost, available for sale securities	70,703	37,507
Gross unrealized gains, available for sale securities	1,002	1,122
Gross unrealized losses, available for sale securities	(378)	(2)
Fair value, available for sale securities	71,327	38,627
Securities held to maturity, at amortized cost (fair value, 2021, $10,262; 2020, $14,743)	2,745	3,146
Gross unrealized gains, held to maturity securities	101	140
Gross unrealized losses, held to maturity securities	0	0
Securities, fair value	2,846	3,286
Amortized cost, held to maturity securities	2,745	3,146
Fair value, held to maturity securities	2,846	3,286
Corporate Debt Securities [Member]
Securities held to maturity, at amortized cost (fair value, 2021, $10,262; 2020, $14,743)	2,027	1,500
Gross unrealized gains, held to maturity securities	9	105
Gross unrealized losses, held to maturity securities	0	0
Securities, fair value	2,036	1,605
Amortized cost, held to maturity securities	2,027	1,500
Fair value, held to maturity securities	$ 2,036	$ 1,605
[1] Derived from audited consolidated financial statements.

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