Reduction in workforce - Narrative (Details) $ in Thousands		1 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($)	Jul. 31, 2021 USD ($) employee	Apr. 30, 2021 USD ($) employee	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expense				$ 25,801	$ 0	$ 0
Stock-based compensation expense				98,740	$ 122,596	$ 131,083
April 2021 reduction
Restructuring Cost and Reserve [Line Items]
Number of employees impacted | employee			50
Restructuring expense			$ 4,600	4,625
July 2021 reduction
Restructuring Cost and Reserve [Line Items]
Number of employees impacted | employee		90
Restructuring expense		$ 21,200		21,176
July 2021 reduction | Unrestricted Stock
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense	$ 2,500
July 2021 reduction | Unrestricted Stock | Research And Development And Selling, General And Administrative Expenses
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense				$ 2,500