Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 9,131	$ 7,915
Cost of revenues	6,264	6,531
Gross profit	2,867	1,384
Operating expenses:
Research and development	5,692	6,009
Selling, general and administrative	16,534	18,404
Total operating expenses	22,226	24,413
Loss from operations	(19,359)	(23,029)
Interest income	288	214
Interest expense	(1,480)	(5,692)
Other income, net	1,101	949
Net loss and comprehensive loss	(19,450)	(27,558)
Accretion of preferred stock dividends	(3,580)	(2,918)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock		(5,216)
Net loss applicable to common stockholders	$ (23,030)	$ (35,692)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (3.18)	$ (33.42)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	7,239	1,068