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Note 6 - Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Equity securities at fair value (Note 2)	$ 3,804	$ 2,896
Securities available for sale (Note 2)	722,627	574,787
Equity Securities [Member]
Equity securities at fair value (Note 2)		2,896
US Treasury and Government [Member]
Securities available for sale (Note 2)	2,041	2,051
US Treasury Securities [Member]
Securities available for sale (Note 2)	11,864	2,056
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale (Note 2)	431,475	320,368
Collateralized Mortgage Backed Securities [Member]
Equity securities at fair value (Note 2)	3,804
Securities available for sale (Note 2)	271,923	246,723
Corporate Debt Securities [Member]
Securities available for sale (Note 2)	1,990	2,589
Trust Preferred Securities [Member]
Securities available for sale (Note 2)	1,000	1,000
Asset-backed Securities [Member]
Securities available for sale (Note 2)	2,334	0
Fair Value, Recurring [Member]
Securities available for sale (Note 2)		574,787
Fair Value, Recurring [Member] | Equity Securities [Member]
Equity securities at fair value (Note 2)	3,804	2,896
Fair Value, Recurring [Member] | US Treasury and Government [Member]
Securities available for sale (Note 2)	2,041	2,051
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Securities available for sale (Note 2)	11,864	2,056
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available for sale (Note 2)	431,475	320,368
Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]
Securities available for sale (Note 2)	271,923	246,723
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Securities available for sale (Note 2)	1,990	2,589
Fair Value, Recurring [Member] | Trust Preferred Securities [Member]
Securities available for sale (Note 2)	1,000	1,000
Fair Value, Recurring [Member] | Asset-backed Securities [Member]
Securities available for sale (Note 2)	2,334
Fair Value, Inputs, Level 1 [Member]
Securities available for sale (Note 2)	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Securities available for sale (Note 2)		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]
Equity securities at fair value (Note 2)	1,859	1,411
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Trust Preferred Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Asset-backed Securities [Member]
Securities available for sale (Note 2)	0
Fair Value, Inputs, Level 2 [Member]
Securities available for sale (Note 2)	709,021
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Securities available for sale (Note 2)		563,364
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]
Equity securities at fair value (Note 2)	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]
Securities available for sale (Note 2)	2,041	2,051
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Securities available for sale (Note 2)	11,864	2,056
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available for sale (Note 2)	418,869	309,945
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]
Securities available for sale (Note 2)	271,923	246,723
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Securities available for sale (Note 2)	1,990	2,589
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Trust Preferred Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Asset-backed Securities [Member]
Securities available for sale (Note 2)	2,334
Fair Value, Inputs, Level 3 [Member]
Securities available for sale (Note 2)	13,606
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Securities available for sale (Note 2)		11,423
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Equity Securities [Member]
Equity securities at fair value (Note 2)	1,945	1,485
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury and Government [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Securities available for sale (Note 2)	12,606	10,423
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Securities available for sale (Note 2)	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Trust Preferred Securities [Member]
Securities available for sale (Note 2)	1,000	$ 1,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Asset-backed Securities [Member]
Securities available for sale (Note 2)	$ 0

X

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
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- Definition

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+ References

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-Name Accounting Standards Codification
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