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Note 2 - Securities - Available-for-sale Securities (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Securities available for sale, amortized cost	$ 306,080,000	$ 329,979,000
Securities available for sale, gross unrealized gains	6,092,000	5,930,000
Securities available for sale, gross unrealized losses	(25,000)	(1,254,000)
Securities available for sale, fair value	312,147,000	334,655,000
US Government Agencies Debt Securities [Member]
Securities available for sale, amortized cost	161,931,000	185,103,000
Securities available for sale, gross unrealized gains	1,893,000	2,449,000
Securities available for sale, gross unrealized losses	0	(1,142,000)
Securities available for sale, fair value	163,824,000	186,410,000
Collateralized Mortgage Backed Securities [Member]
Securities available for sale, amortized cost	38,514,000	41,998,000
Securities available for sale, gross unrealized gains	1,258,000	554,000
Securities available for sale, gross unrealized losses	(3,000)	(82,000)
Securities available for sale, fair value	39,769,000	42,470,000
Municipal General Obligation Bonds [Member]
Securities available for sale, amortized cost	101,006,000	98,245,000
Securities available for sale, gross unrealized gains	2,880,000	2,864,000
Securities available for sale, gross unrealized losses	(21,000)	(30,000)
Securities available for sale, fair value	103,865,000	101,079,000
Municipal Revenue Bonds [Member]
Securities available for sale, amortized cost	4,129,000	4,133,000
Securities available for sale, gross unrealized gains	61,000	63,000
Securities available for sale, gross unrealized losses	(1,000)	0
Securities available for sale, fair value	4,189,000	4,196,000
Other Debt and Equity Securities [Member]
Securities available for sale, amortized cost	500,000	500,000
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	0	0
Securities available for sale, fair value	$ 500,000	$ 500,000

X

- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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- Definition

Amortized cost 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
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454

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- 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
-Topic 942
-SubTopic 210
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