Employee benefit plans - Fair Value Measurement of Pension Plan Assets (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure
Fair value of pension plan assets	$ 17,609	$ 16,106	$ 19,257
Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of pension plan assets	783	759
U.S. large cap
Defined Benefit Plan Disclosure
Fair value of pension plan assets	9,482	7,365
International
Defined Benefit Plan Disclosure
Fair value of pension plan assets	1,671	2,338
U.S. Treasury securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	343	511
U.S. Government Agencies
Defined Benefit Plan Disclosure
Fair value of pension plan assets	2,149	1,991
Corporate bonds
Defined Benefit Plan Disclosure
Fair value of pension plan assets	3,181	3,142
Level 1
Defined Benefit Plan Disclosure
Fair value of pension plan assets	11,936	10,462
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of pension plan assets	783	759
Level 1 | U.S. large cap
Defined Benefit Plan Disclosure
Fair value of pension plan assets	9,482	7,365
Level 1 | International
Defined Benefit Plan Disclosure
Fair value of pension plan assets	1,671	2,338
Level 2
Defined Benefit Plan Disclosure
Fair value of pension plan assets	5,673	5,644
Level 2 | U.S. Treasury securities
Defined Benefit Plan Disclosure
Fair value of pension plan assets	343	511
Level 2 | U.S. Government Agencies
Defined Benefit Plan Disclosure
Fair value of pension plan assets	2,149	1,991
Level 2 | Corporate bonds
Defined Benefit Plan Disclosure
Fair value of pension plan assets	$ 3,181	$ 3,142