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Note 6 - Investment Securities Available for Sale - Gross Unrealized Losses and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Less than Twelve Months, Fair Value	$ 11,957	$ 36,925
Less than Twelve Months, Gross Unrealized Losses	(84)	(699)
Twelve Months or Greater, Fair Value	9,121	5,754
Twelve Months or Greater, Gross Unrealized Losses	(201)	(184)
Total, Fair Value	21,078	42,679
Total, Gross Unrealized Losses	(285)	(883)
US Government Agencies Debt Securities [Member]
Less than Twelve Months, Fair Value	952	3,803
Less than Twelve Months, Gross Unrealized Losses	(9)	(47)
Twelve Months or Greater, Fair Value	3,211	1,316
Twelve Months or Greater, Gross Unrealized Losses	(47)	(49)
Total, Fair Value	4,163	5,119
Total, Gross Unrealized Losses	(56)	(96)
US States and Political Subdivisions Debt Securities [Member] | Tax Exempt [Member]
Less than Twelve Months, Fair Value	3,008	23,554
Less than Twelve Months, Gross Unrealized Losses	(18)	(522)
Twelve Months or Greater, Fair Value	2,112	0
Twelve Months or Greater, Gross Unrealized Losses	(41)
Total, Fair Value	5,120	23,554
Total, Gross Unrealized Losses	(59)	(522)
US States and Political Subdivisions Debt Securities [Member] | Taxable [Member]
Less than Twelve Months, Fair Value		502
Less than Twelve Months, Gross Unrealized Losses		(4)
Twelve Months or Greater, Fair Value
Twelve Months or Greater, Gross Unrealized Losses
Total, Fair Value		502
Total, Gross Unrealized Losses		(4)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Less than Twelve Months, Fair Value	7,997	9,066
Less than Twelve Months, Gross Unrealized Losses	(57)	(126)
Twelve Months or Greater, Fair Value	3,798	4,438
Twelve Months or Greater, Gross Unrealized Losses	(113)	(135)
Total, Fair Value	11,795	13,504
Total, Gross Unrealized Losses	$ (170)	$ (261)

X

- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

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-Publisher FASB
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-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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