Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Stock-Based Compensation
Stock-based compensation expense	$ 339	$ 66
Remaining unrecognized stock-based compensation expense	$ 4,400
Weighted average period for recognition of stock-based compensation expense	3 years 3 months 3 days
Cost of revenue
Stock-Based Compensation
Stock-based compensation expense	$ 3	2
Research and development expenses
Stock-Based Compensation
Stock-based compensation expense	60	17
Selling, general and administrative expenses
Stock-Based Compensation
Stock-based compensation expense	$ 276	$ 47

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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