Pension and Other Post-Retirement Benefits - Projected benefit obligations, the plan assets, and the funded status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in benefit obligation
Projected benefit obligation at beginning of year	$ 21,615	$ 16,563
Service costs	1,441	1,136	$ 870
Interest cost	323	292	311
Plan participant contributions	134	124
Actuarial (gains) losses	(503)	695
Defined Benefit Plan, Benefit Obligation, Business Combination	918	2,393
Benefit payments	(872)	(357)
Expenses paid from assets	(43)	(40)
Effect of foreign currency translation	(1,283)	1,319
Projected benefit obligation at end of year	21,473	21,615	16,563
Change in plan assets
Fair value of plan assets at beginning of year	6,665	5,487
Actual return on plan assets	262	213
Plan participant contributions	134	124
Defined Benefit Plan, Plan Assets, Business Combination	0	99
Employer contributions	1,366	583
Benefit payments	(872)	(357)
Expenses paid from assets	43	40
Effect of foreign currency translation	(538)	556
Fair value of plan assets at end of year	6,717	6,665	$ 5,487
Unfunded status	(14,756)	(14,950)
Defined Benefit Plan, Plan Assets, Payment for Settlement	(257)	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	(257)	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	$ 0	$ (510)