Lease obligation - Operating sublease income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lease obligation
Operating sublease income		$ 1,380	$ 838
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating Expenses	Operating Expenses	Operating Expenses