Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	$ 918	$ 798	$ 1,723	$ 1,502
Research and development
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	194	161	356	308
General and administrative
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	646	556	1,231	1,065
Sales and marketing
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	$ 78	$ 81	$ 136	$ 129