Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	$ 910	$ 895	$ 2,633	$ 2,397
Research and development
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	182	176	538	484
General and administrative
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	657	627	1,888	1,692
Sales and marketing
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	$ 71	$ 92	$ 207	$ 221