Condensed Consolidated Statements Of Operations And Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues:
Revenues	$ 265		$ 709
Cost and expenses:
Cost of revenues	1,344		2,253
Research and development	5,458	$ 7,459	12,227	$ 16,522
Sales and marketing	3,690	3,147	9,231	7,293
General and administrative	3,787	4,200	8,285	9,516
Total costs and expenses	14,279	14,806	31,996	33,331
Loss from operations	(14,014)	(14,806)	(31,287)	(33,331)
Other income (expense):
Interest income (expense), net	18	(517)	18	(631)
Total other income (expense)	18	(517)	18	(631)
Net loss	(13,996)	(15,323)	(31,269)	(33,962)
Other comprehensive gain (loss):
Unrealized gain on available-for-sale securities				1
Comprehensive loss	$ (13,996)	$ (15,323)	$ (31,269)	$ (33,961)
Net loss per share:
Basic net loss per share	$ (0.44)	$ (0.58)	$ (1.02)	$ (1.29)
Diluted net loss per share	$ (0.44)	$ (0.58)	$ (1.02)	$ (1.29)
Weighted average shares used to compute net loss per common share — basic	31,492	26,477	30,623	26,276
Weighted average shares used to compute net loss per common share — diluted	31,492	26,477	30,623	26,276
Product [Member]
Revenues:
Revenues	$ 265		$ 709