CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue	$ 810	$ 1,374	$ 2,701	$ 4,004
Cost of revenue	2,525	2,765	7,715	5,131
Gross loss	(1,715)	(1,391)	(5,014)	(1,127)
Research and development expenses	23,787	26,123	76,306	77,376
General and administrative expenses	8,474	8,093	24,020	23,642
Selling and marketing expenses	1,520	2,195	5,603	5,415
Total operating expenses	33,781	36,411	105,929	106,433
Operating loss	(35,496)	(37,802)	(110,943)	(107,560)
Interest income	2,219	1,164	6,508	2,033
Other income, net	39	135	68	896
Loss before income taxes	(33,238)	(36,503)	(104,367)	(104,631)
Income tax provision	0	0	0	0
Net loss	(33,238)	(36,503)	(104,367)	(104,631)
Unrealized gain (loss) on available-for-sale securities	915	(752)	2,604	(4,157)
Total comprehensive loss	$ (32,323)	$ (37,255)	$ (101,763)	$ (108,788)
Net loss per share, Basic	$ (0.15)	$ (0.17)	$ (0.47)	$ (0.48)
Net loss per share, Diluted	$ (0.15)	$ (0.17)	$ (0.47)	$ (0.48)
Weighted average shares of common stock outstanding - Basic	222,825,819	217,888,470	221,003,348	216,937,433
Weighted-average shares used in computing net loss per share - diluted	222,825,819	217,888,470	221,003,348	216,937,433