Employee Benefits Plans - Valuation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Valuation
Maximum percentage of unrecognized gains (losses) for amortization	10.00%
Amortization period for gains (losses) of defined benefit plans	15 years
Fair value of plan assets	$ 89,972	$ 87,215	$ 75,875
Weighted-average assumptions used to determine net periodic benefit cost:
Expected asset return	2.73%
U.K. Pension Plan
Valuation
Historical performance period	10 years
Weighted-average assumptions used to determine benefit obligations:
Discount rate	1.80%	1.40%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	1.40%	2.10%
Expected asset return	2.72%	3.47%
U.K. Pension Plan | Minimum
Valuation
Historical performance period	15 years	10 years
U.K. Pension Plan | Maximum
Valuation
Historical performance period	20 years	20 years
Asterion Pension Plan
Weighted-average assumptions used to determine benefit obligations:
Discount rate	1.13%	0.79%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	1.13%	0.79%
Expected asset return	1.13%	0.79%
Norway Pension Plan
Weighted-average assumptions used to determine benefit obligations:
Discount rate	1.90%	1.70%
Rate of compensation increase	2.75%	2.25%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	1.90%	1.70%
Expected asset return	3.10%	2.70%
Rate of compensation increase	2.75%	2.25%
German Pension Plan
Weighted-average assumptions used to determine benefit obligations:
Discount rate	1.00%	0.75%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	1.00%	0.75%
Unfunded Plan | German Pension Plan
Valuation
Fair value of plan assets	$ 0