Stock Options - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock options
Stock-based compensation expense included in Total operating expenses	$ 18,409	$ 7,172	$ 4,872
Stock options
Stock options
Stock-based compensation expense included in Total operating expenses	14,528	5,725	4,230
Unvested restricted stock units
Stock options
Stock-based compensation expense included in Total operating expenses	3,522	1,187	410
Employee stock purchase plan
Stock options
Stock-based compensation expense included in Total operating expenses	359	260	232
Research and development
Stock options
Stock-based compensation expense included in Total operating expenses	9,984	3,841	2,245
General and administrative
Stock options
Stock-based compensation expense included in Total operating expenses	$ 8,425	$ 3,331	$ 2,627