Stock Based Compensation, Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-Based Compensation Expense [Abstract]
Total share based compensation expense	$ 7,311	$ 4,489	$ 15,211	$ 8,450
Research and Development [Member]
Stock-Based Compensation Expense [Abstract]
Total share based compensation expense	3,148	1,679	6,064	3,414
General and Administrative [Member]
Stock-Based Compensation Expense [Abstract]
Total share based compensation expense	4,163	2,810	9,147	5,036
Stock Options [Member]
Stock-Based Compensation Expense [Abstract]
Total share based compensation expense	7,215	4,489	15,041	8,450
Restricted Stock Units [Member]
Stock-Based Compensation Expense [Abstract]
Total share based compensation expense	$ 96	$ 0	$ 170	$ 0