Condensed Consolidated Statement of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 299	$ 0	$ 357	$ 278
Operating expenses:
Cost of revenue (exclusive of amortization)	21	0	21	0
Research and development	27,103	25,526	66,897	49,521
Selling, general and administrative	29,606	13,596	50,830	26,506
Amortization	674	0	674	0
Operating Costs and Expenses	57,404	39,122	118,422	76,027
Loss from operations	(57,105)	(39,122)	(118,065)	(75,749)
Interest income	964	1,596	2,455	3,166
Interest expense	(4,256)	0	(6,404)	0
Changes in fair value of derivative liability	(59)	21	(149)	(71)
Other income (expense), net	(134)	115	(260)	(40)
Loss before income taxes	(60,590)	(37,390)	(122,423)	(72,694)
Income tax provision	0	0	(100)	0
Net loss	(60,590)	(37,390)	(122,523)	(72,694)
Unrealized gain (loss) and adjustment on securities included in net loss	(407)	46	114	124
Comprehensive loss	(60,997)	(37,344)	(122,409)	(72,570)
Basic and diluted net loss	$ (60,590)	$ (37,390)	$ (122,523)	$ (72,694)
Basic and diluted net loss (in dollar per share)	$ (1.12)	$ (0.86)	$ (2.27)	$ (1.71)
Basic and diluted weighted-average number of shares used in computing net loss per share (in shares)	54,257,320	43,260,317	54,062,678	42,434,137