Income taxes - Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 0	$ 0	$ 0
State	46	11	0
Foreign	185	205	9
Total current tax provision	231	216	9
Deferred:
Federal	(62)	(2,924)	(17,703)
State	0	(2,314)	(2,424)
Foreign	0	0	0
Total deferred tax benefit	(62)	(5,238)	(20,127)
Income tax expense (benefit)	$ 169	$ (5,022)	$ (20,118)