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Note 4 - Fair Value Disclosure Measurements - Assets Measured on a Recurring Basis (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Investment securities available for sale, at fair value	$ 98,334,000	$ 114,376,000
Impaired loans	11,859,000	12,430,000
Other real estate owned	557,000	934,000
Estimate of Fair Value Measurement [Member]
Investment securities available for sale, at fair value	98,334,000	114,376,000
Impaired loans	1,620,000	6,498,000
Other real estate owned	81,000	511,000
US Government Agencies Debt Securities [Member]
Investment securities available for sale, at fair value	9,094,000	10,236,000
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, at fair value	72,094,000	81,223,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment securities available for sale, at fair value	16,579,000	20,069,000
Debt Securities [Member]
Investment securities available for sale, at fair value	97,767,000	113,237,000
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Investment securities available for sale, at fair value		1,709,000
Equity Securities In Financial Institutions [Member]
Investment securities available for sale, at fair value	567,000	1,139,000
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member]
Investment securities available for sale, at fair value	98,334,000	114,376,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	98,334,000	114,376,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Investment securities available for sale, at fair value	9,094,000	10,236,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, at fair value	72,094,000	81,223,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment securities available for sale, at fair value	16,579,000	20,069,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Investment securities available for sale, at fair value	97,767,000	113,237,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Investment securities available for sale, at fair value		1,709,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities In Financial Institutions [Member]
Investment securities available for sale, at fair value	567,000	1,139,000
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Impaired loans	1,620,000	6,498,000
Other real estate owned	$ 81,000	$ 511,000

X

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04(c)(Schedule III))
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28)
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

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