CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Total revenues	$ 1,313	$ 1,836	$ 7,895	$ 3,049
Operating expenses:
Cost of revenue	0	141	1,000	141
Research and development	26,021	18,864	46,477	34,708
General and administrative	20,124	7,038	37,255	14,176
Total operating expenses	46,145	26,043	84,732	49,025
Loss from operations	(44,832)	(24,207)	(76,837)	(45,976)
Interest expense	(1,202)	(1,226)	(2,302)	(2,583)
Other income, net	847	477	798	1,230
Loss before provision for income taxes	(45,187)	(24,956)	(78,341)	(47,329)
Provision for income taxes	2	0	3	0
Net loss	$ (45,189)	$ (24,956)	$ (78,344)	$ (47,329)
Net loss per share - basic (in dollars per share)	$ (0.45)	$ (0.28)	$ (0.79)	$ (0.53)
Net loss per share - diluted (in dollars per share)	$ (0.45)	$ (0.28)	$ (0.79)	$ (0.53)
Shares used in computing net loss per share - basic	100,040,083	89,080,046	98,617,564	88,890,353
Shares used in computing net loss per share - diluted	100,040,083	89,080,046	98,617,564	88,890,353
Comprehensive loss:
Net loss	$ (45,189)	$ (24,956)	$ (78,344)	$ (47,329)
Unrealized gains on available-for-sale securities	11	361	8	297
Comprehensive loss	(45,178)	(24,595)	(78,336)	(47,032)
Collaborative development revenue
Revenues:
Total revenues	1,310	1,125	2,764	2,300
Product supply revenue
Revenues:
Total revenues	0	5	126	43
Licensing revenue
Revenues:
Total revenues	$ 3	$ 706	$ 5,005	$ 706