Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenues:
Total revenues	$ 0	$ 444
Cost and expenses:
Cost of revenues	0	909
Research and development	5,829	6,769
Sales and marketing	0	5,541
General and administrative	3,733	4,498
Total cost and expenses	9,562	17,717
Loss from operations	(9,562)	(17,273)
Other income (expense):
Interest income (expense), net	(239)	0
Total other income (expense)	(239)	0
Loss from operations, before income taxes	(9,801)	(17,273)
Income tax benefit	0	0
Net loss	(9,801)	(17,273)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	0	0
Comprehensive loss	$ (9,801)	$ (17,273)
Net loss per share:
Basic and diluted net loss per share (in dollars per share)	$ (0.26)	$ (0.58)
Weighted average shares used to compute net loss per common share — basic and diluted (in shares)	37,390	29,745
Product [Member]
Revenues:
Total revenues	$ 0	$ 444