Summary of significant accounting policies - Contract assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Contract with Customer, Asset, Allowance for Credit Loss [Roll Forward]
Balance, beginning of the period	$ 1,792	$ 947	$ 499
Balance, end of the period	817	1,792	947
Change	$ (975)	$ 845	$ 448