Income taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Increase—income tax benefit	$ 94,232,000	$ 8,011,000
Net operating loss carryforwards, federal	402,000,000
Net operating loss carryforwards, state	$ 294,000,000
Deferred tax assets, operating loss carryforwards expiration period	5 years
Percentage of taxable income limitation	80.00%
Deferred tax assets, operating loss carryforwards expiration year	2036
Unrecognized tax benefits	$ 968,000.000	$ 229,000	$ 100,000
Interest and penalties related to uncertain tax positions	0
Income tax examination, liability (refund)	0
Federal [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards, research	$ 3,200,000
Deferred tax assets, tax credit carryforwards, research expiration year	2036
Year under examination	2017
State [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards, research	$ 1,900,000
Year under examination	2017