Note 4 - Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Investment securities available for sale, amortized cost	$ 156,410,000	$ 174,370,000
Investment securities available for sale, gross unrealized gains	3,125,000	361,000
Investment securities available for sale, gross unrealized losses	(215,000)	(3,224,000)
Investment securities available for sale, Estimated fair value	159,320,000	171,507,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment securities available for sale, amortized cost	123,940,000	135,059,000
Investment securities available for sale, gross unrealized gains	1,924,000	240,000
Investment securities available for sale, gross unrealized losses	(186,000)	(2,621,000)
Investment securities available for sale, Estimated fair value	125,678,000	132,678,000
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, amortized cost	32,470,000	39,311,000
Investment securities available for sale, gross unrealized gains	1,201,000	121,000
Investment securities available for sale, gross unrealized losses	(29,000)	(603,000)
Investment securities available for sale, Estimated fair value	$ 33,642,000	$ 38,829,000

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).

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-SubTopic 10
-Section 50
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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).

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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

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-Publisher FASB
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