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Balance Sheet Details - Additional Information (Details) - USD ($)
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]          
Depreciation expense $ 88,000 $ 2,000 $ 217,000 $ 2,000  
Disposal of property, plant or equipment     $ 0   $ 0