Note 4 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	195.00%	315.00%
Unrecognized Tax Benefits, Ending Balance	$ 1,800
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0
Deferred Tax Assets, Net, Total	$ 0
Domestic Tax Authority [Member] \| Internal Revenue Service (IRS) [Member]
Open Tax Year	2015 2016 2017 2018
Open Tax Period	3 years
State and Local Jurisdiction [Member] \| California Franchise Tax Board [Member]
Open Tax Year	2014 2015 2016 2017 2018
Open Tax Period	4 years

The period of time that certain aspects of the business may be under review for tax purposes.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Tax year that remains open to examination under enacted tax laws, in CCYY format.

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Amount of unrecognized tax benefits.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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