Note 3 - Significant Risk and Uncertainty (Details Textual)	3 Months Ended
Mar. 31, 2018 USD ($)	Mar. 31, 2017	Dec. 31, 2017 USD ($)
Cash, Uninsured Amount	$ 11,724,000		$ 12,198,000
Export Sales To Unaffiliated Customers As Percentage Of Total Sales	10.00%
Number Of Major Customers	1	1
Customer Concentration Risk [Member] \| Sales Revenue, Net [Member] \| Customer A [Member]
Concentration Risk, Percentage	48.00%	70.00%
Customer Concentration Risk [Member] \| Accounts Receivable [Member] \| One Customer [Member]
Concentration Risk, Percentage	82.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
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-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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