Comprehensive Income - Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Comprehensive Income
Foreign currency translation adjustments	$ (8,985)	$ (7,954)	$ (8,640)	$ (8,596)
Pension liability, net of tax	(9,211)	(9,357)	(11,414)	(11,597)
Total accumulated other comprehensive loss	$ (18,196)	$ (17,311)	$ (20,054)	$ (20,193)