Balance Sheet Components - Components of Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued vacation	$ 4,480	$ 3,809
Accrued payroll and related expenses	8,375	19,156
Accrued ESPP contribution	1,776	417
Accrued professional services fees	181	2,846
Accrued interest	128	128
Claims payable	3,159	2,802
Other	5,148	3,556
Total accrued liabilities	$ 23,247	$ 32,714	$ 20,536