Note 11 - Income Taxes (Details Textual) - USD ($) |
12 Months Ended | ||
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Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
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Income Tax Expense (Benefit), Total | $ 0 | ||
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount | 11,667,000 | $ 1,501,000 | |
Deferred Tax Assets, Tax Credit Carryforwards, Research | 951,000 | 835,000 | |
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total | 0 | ||
Unrecognized Tax Benefits, Ending Balance | $ 450,000 | $ 397,000 | $ 268,000 |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent | 21.00% | 34.00% | |
Domestic Tax Authority [Member] | |||
Operating Loss Carryforwards, Total | $ 126,893,000 | ||
Deferred Tax Assets, Tax Credit Carryforwards, Research | 830,000 | ||
State and Local Jurisdiction [Member] | |||
Operating Loss Carryforwards, Total | 97,677,000 | ||
Deferred Tax Assets, Tax Credit Carryforwards, Research | $ 668,000 |
X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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X | ||||||||||
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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X | ||||||||||
- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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X | ||||||||||
- Definition Amount of unrecognized tax benefits. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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X | ||||||||||
- Definition 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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X | ||||||||||
- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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