Note 11 - Fair Values (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale, Total	$ 337,876,000	$ 337,366,000
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Ending Balance	$ 1,800,000	1,100,000
Real Estate Dependent Loans and Foreclosed Assets Estimated Selling Costs [Member]
Fair Value Inputs, Discount Factor	10.00%
Real Estate Dependent Loans and Foreclosed Assets [Member] \| Commercial Real Estate [Member] \| Minimum [Member]
Fair Value Inputs, Discount Factor	15.00%
Real Estate Dependent Loans and Foreclosed Assets [Member] \| Commercial Real Estate [Member] \| Maximum [Member]
Fair Value Inputs, Discount Factor	25.00%
Real Estate Dependent Loans and Foreclosed Assets [Member] \| Residential Real Estate [Member] \| Minimum [Member]
Fair Value Inputs, Discount Factor	25.00%
Real Estate Dependent Loans and Foreclosed Assets [Member] \| Residential Real Estate [Member] \| Maximum [Member]
Fair Value Inputs, Discount Factor	50.00%
Municipal General Obligation Bonds [Member]
Debt Securities, Available-for-sale, Total	$ 105,112,000	102,497,000
Fair Value, Inputs, Level 1 [Member]
Debt Securities, Available-for-sale, Total	0	0
Fair Value, Inputs, Level 3 [Member] \| Municipal General Obligation Bonds [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		1,500,000
Available-for-sale Securities [Member]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount, Ending Balance	$ 0	$ 0

Discount factor used to further reduce the balance sheet carrying amount of property or other assets.

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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 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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- Definition

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

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- Definition

Amount of valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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