Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred income tax assets
Net operating loss carryforwards	$ 57,763	$ 49,211
Tax credit carryforwards	12,422	8,638
Stock-based compensation	6,011	5,142
Compensation accruals	7,026	2,297
Lease liability	17,540	18,404
Accruals and reserves	2,079	795
Gross deferred income tax assets	102,841	84,487
Valuation allowance	(44,307)	(62,274)
Total deferred income tax assets, net of valuation allowance	58,534	22,213
Deferred income tax liabilities
Intangible assets	(514)	(605)
Prepaid expenses	0	(1,688)
Convertible senior notes	(45,616)	(5,359)
Right-of-use assets	(12,404)	(13,579)
Fixed assets	0	(982)
Total deferred income tax liabilities	(58,534)	(22,213)
Net deferred income tax assets and liabilities	$ 0	$ 0