Comprehensive Income - Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Comprehensive Income
Foreign currency translation adjustments	$ (9,046)	$ (7,954)	$ (8,902)	$ (8,596)
Pension liability, net of tax	(9,284)	(9,357)	$ (11,498)	$ (11,597)
Total accumulated other comprehensive loss	$ (18,330)	$ (17,311)