Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues:
Total revenues	$ 700	$ 1,418	$ 0
Cost and expenses:
Cost of revenues	11,944	1,968	0
Research and development	20,839	28,640	26,444
Sales and marketing	12,019	14,751	7,256
General and administrative	13,955	19,073	16,265
Total cost and expenses	58,757	64,432	49,965
Loss from operations	(58,057)	(63,014)	(49,965)
Other income (expense):
Interest income (expense), net	(448)	(646)	114
Total other income (expense)	(448)	(646)	114
Loss from operations, before income taxes	(58,505)	(63,660)	(49,851)
Income tax benefit	0	0	0
Net loss	(58,505)	(63,660)	(49,851)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	0	1	(5)
Comprehensive loss	$ (58,505)	$ (63,659)	$ (49,856)
Net loss per share:
Basic and diluted net loss per share (in dollars per share)	$ (1.72)	$ (2.28)	$ (2.14)
Weighted average shares used to compute net loss per common share — basic and diluted (in shares)	33,935	27,964	23,248
Product [Member]
Revenues:
Total revenues	$ 700	$ 1,418	$ 0