Note 2 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)
Number of Operating Segments	1
Number of Reportable Segments	1
Debt Securities, Available-for-sale, Realized Gain (Loss), Total	$ 0	$ 0
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Total	0	0
Liability for Uncertainty in Income Taxes, Current	$ 0	$ 0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Current			$ 200
Operating Lease, Weighted Average Discount Rate, Percent			8.00%
Operating Lease, Right-of-Use Asset			$ 200

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
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Amount recognized for uncertainty in income taxes classified as current.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

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-Publisher FASB
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-Section 45
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Amount of lessee's right to use underlying asset under operating lease.

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Weighted average discount rate for operating lease calculated at point in time.

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Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI).

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