Stock-Based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Options to purchase common stock
Stock based compensation expense
Options granted (in shares)	221,000
Stock-based compensation expense	$ 35,087	$ 23,232
Unrecognized compensation expense	$ 368,900
Unrecognized compensation expense, weighted average period of recognition	3 years
Options to purchase common stock | Cost of revenues
Stock based compensation expense
Stock-based compensation expense	$ 1,716	708
Options to purchase common stock | Research and development
Stock based compensation expense
Stock-based compensation expense	9,421	3,874
Options to purchase common stock | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	23,950	18,650
Employee stock options
Stock based compensation expense
Stock-based compensation expense	34,597	22,962
Employee stock options | Cost of revenues
Stock based compensation expense
Stock-based compensation expense	1,716	708
Employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	9,006	3,650
Employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	$ 23,875	18,604
Non-employee stock options
Stock based compensation expense
Options granted (in shares)	28,053
Stock-based compensation expense	$ 490	270
Non-employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	415	224
Non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	$ 75	$ 46