Note 6 - Goodwill and Intangible Assets (Details Textual)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition Number of Acquisitions Resulting in Goodwill	4		4
Goodwill, Impairment Loss			$ 0		$ 0
Business Acquisition, Number of Acquisitions Resulting in Intangible Assets	3		3
Amortization of Intangible Assets, Total	$ 67,000	$ 58,000	$ 203,000	$ 177,000

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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