Balance Sheet Components - Other Long-Term Liabilities (Additional Information) (Details) - USD ($) $ in Thousands	103 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Mar. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Grants receivable			$ 16,500
Proceeds from government grants	$ 12,000
Grant agreement, recapture provision repayments	1,500
Delaware grant	9,212	$ 10,469
Deferred government grant obligation, current	$ 1,300