Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,053	$ 3,415	$ 8,521	$ 7,066
Restricted stock awards | Deferred Salary And Bonuses Settlement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	14,620	0
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1,879	933	2,873	2,493
Research and development | Restricted stock awards | Deferred Salary And Bonuses Settlement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	6,061	0
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	538	215	847	633
Sales and marketing | Restricted stock awards | Deferred Salary And Bonuses Settlement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	1,797	0
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	2,636	2,267	$ 4,801	$ 3,940
General and administrative | Restricted stock awards | Deferred Salary And Bonuses Settlement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 6,762	$ 0