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Significant Accounting Policies (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Jan. 01, 2019
Significant Accounting Policies |  |  |
Minimum period for maturity dates for short-term investments | 90 days | 90 days |
Accumulated deficit | $ (445,070) | $ (435,684) |
Lease accounting |  |  |
Operating lease liabilities | 89 |  |
Right of use operating assets | $ 89 |  |
Discount rate used for discounting future payments | 13.60% |  |
Current operating liability | $ 81 |  |
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] | Accrued Liabilities, Current |  |
Non current operating liabilities | $ 8 |  |
Minimum |  |  |
Lease accounting |  |  |
Lessee, Operating Lease, Renewal Term | 3 months 18 days |  |
Maximum |  |  |
Lease accounting |  |  |
Lessee, Operating Lease, Renewal Term | 2 years 3 months 18 days |  |
Accounting Standards Update 2016-02 |  |  |
Lease accounting |  |  |
Operating lease liabilities |  |  | $ 186
Right of use operating assets |  |  | $ 186

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