Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	$ 3,968	$ 3,554
Research and development
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	903	736
General and administrative
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	2,710	2,460
Sales and marketing
Operating expenses include stock-based compensation as follows:
Total stock-based compensation	$ 355	$ 358