Income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 0	$ 0
Increase in valuation allowance	7,800	3,700
Federal operating loss	68,800	47,300
State net operating loss	69,200	47,700
Net operating loss generated not subject to expiration	51,800
Uncertain tax positions	0	$ 0
Percentage of taxable income offset from net operating loss		80.00%
Interest and penalties	0	$ 0
Federal
Operating Loss Carryforwards [Line Items]
R&D tax credits	$ 2,000