Stockholders' Equity - Summary of Stock-Based Compensation Expense related to Stock-Based Payment Awards Granted (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]
Stock-based compensation expense	$ 11,236	$ 11,095	$ 33,963	$ 34,183
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	4,521	4,612	14,130	14,580
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	2,836	3,277	8,414	10,012
Selling and Marketing Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 3,879	$ 3,206	$ 11,419	$ 9,591