Note 1 - Organization and Summary of Significant Accounting Policies - Adjustments for Adoption of New Lease Standard (Details) - USD ($) $ in Thousands |
Jun. 30, 2019 |
Jan. 01, 2019 |
Dec. 31, 2018 |
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|---|---|---|---|---|---|---|---|---|---|---|---|
| Operating lease right-of-use assets | $ 4,326 | [1] | |||||||||
| Accrued liabilities | 4,276 | 4,540 | [1] | ||||||||
| Operating lease liabilities, current portion | 759 | [1] | |||||||||
| Operating lease liabilities, net of current portion | 4,239 | [1] | |||||||||
| Accumulated deficit | $ (370,952) | $ (345,019) | |||||||||
| Accounting Standards Update 2016-02 [Member] | |||||||||||
| Operating lease right-of-use assets | $ 4,730 | ||||||||||
| Accrued liabilities | [2] | (100) | |||||||||
| Operating lease liabilities, current portion | 484 | ||||||||||
| Operating lease liabilities, net of current portion | 4,610 | ||||||||||
| Deferred rent, net of current portion | (416) | ||||||||||
| Accumulated deficit | [3] | $ (153) | |||||||||
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