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Basis of Presentation and Significant Accounting Policies - Leases (Details) $ in Thousands |  | 12 Months Ended |
--- | --- | --- | ---
Jan. 01, 2019 USD ($) | Dec. 31, 2019 USD ($) facility | Dec. 31, 2018 USD ($)
Accounting Policies |  |  |
Lease, Practical Expedients, Package | true |  |
Operating lease right-of-use assets |  | $ 510 |
Operating lease liabilities |  | $ 573 |
Lease-related Costs |  |  |
Accounting Policies |  |  |
Restructuring liability |  |  | $ 1,700
ASC 842 |  |  |
Accounting Policies |  |  |
Change in Accounting Principle, Accounting Standards Update, Adopted | true |  |
New Accounting Pronouncement or Change in Accounting Principle, Prior Period Not Restated | true |  |
ASC 842 | Restatement Adjustment |  |  |
Accounting Policies |  |  |
Operating lease right-of-use assets | $ 7,400 |  |
Operating lease liabilities | $ 9,200 |  |
Leased facilities, Emeryville, California |  |  |
Accounting Policies |  |  |
Operating leases, number of leased facilities | facility |  | 1 |

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