Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue:
Total revenue	$ 7,234	$ 6,956
Costs and expenses:
Research and development	6,656	4,665
Selling, general and administrative	9,230	6,203
Total costs and expenses	22,091	16,658
Loss from operations	(14,857)	(9,702)
Other income (expense):
Interest income	3	6
Interest expense	(1,650)	(1,013)
Other income, net	9	49
Total other expense	(1,638)	(958)
Net loss	$ (16,495)	$ (10,660)
Net loss per share — basic and diluted	$ (0.10)	$ (0.07)
Weighted-average number of common shares used in computing net loss per share — basic and diluted	169,855,170	148,231,412
Other comprehensive loss:
Net loss	$ (16,495)	$ (10,660)
Net unrealized gain (loss) on marketable securities arising during the period	(7)	9
Less: net realized gain on marketable securities included in net loss		(2)
Total other comprehensive (loss) income, net of taxes	(7)	7
Comprehensive loss	(16,502)	(10,653)
Product [Member]
Revenue:
Total revenue	3,844	4,650
Costs and expenses:
Cost of product revenue	6,205	5,790
Contribution [Member]
Revenue:
Total revenue	$ 3,390	$ 2,306