Share-Based Compensation - Components of 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]
Stock compensation expense	$ 6,217	$ 0	$ 14,185	$ 0
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	2,588	0	5,185	0
Selling, general, and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 3,629	$ 0	$ 9,000	$ 0