Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 42,042	$ 23,403
General and administrative	15,641	13,058
Total operating expenses	57,683	36,461
Loss from operations	(57,683)	(36,461)
Interest and other income, net	3,261	4,825
Other expenses	(58)	0
Total other income (expense), net	3,203	4,825
Loss before income taxes	(54,480)	(31,636)
Benefit from income taxes	0	50
Net loss	(54,480)	(31,586)
Other comprehensive income:
Net unrealized gain on available-for-sale investments	465	1,099
Net comprehensive loss	$ (54,015)	$ (30,487)
Net loss per share, basic and diluted (in dollars per share)	$ (0.50)	$ (0.32)
Weighted-average number of shares used in computing net loss per share, basic and diluted (in shares)	108,963,522	97,315,890