Note 4 - Income Taxes (Details Textual) $ in Thousands	Jun. 30, 2020 USD ($)
Unrecognized Tax Benefits, Ending Balance	$ 1,500
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]
Operating Loss Carryforwards, Total	333,000
State and Local Jurisdiction [Member] \| California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	$ 225,000

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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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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