Nature of Business and Overview (Details) $ in Thousands		12 Months Ended
	Feb. 08, 2019	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Nature of Business and Overview
Reverse stock split	0.067
Cash, cash equivalents and marketable securities		$ 408,300
Net loss		(70,511)	$ (59,780)	$ (50,878)
Net cash used in operations		(60,909)	(40,404)	$ (46,415)
Gross carrying amount of indefinite-lived		$ 27,200	$ 30,700