Note 9 - Income Taxes (Details Textual) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Unrecognized Tax Benefits, Ending Balance	$ 0	$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	0	$ 0
Liability for Uncertainty in Income Taxes, Current	$ 0

Amount recognized for uncertainty in income taxes classified as current.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 10B
-URI http://asc.fasb.org/extlink&oid=84176650&loc=SL37586934-109318

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
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