Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Unusual Risk or Uncertainty [Line Items]
Cash, cash equivalents and marketable securities	$ 423,100						$ 423,100
Net loss	(20,452)	$ (13,373)	$ (16,538)	$ (14,224)	$ (11,031)	$ (12,625)	(50,363)	$ (37,880)
Net cash used in operations							(46,386)	(35,193)
Indefinite-lived intangible assets	27,200						27,200		$ 30,700
Intangible asset impairment	$ 3,500						3,500	$ 3,500
COVID-19
Unusual Risk or Uncertainty [Line Items]
Intangible asset impairment							$ 27,200