Employee Benefit Obligations - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Net Periodic Benefit Cost
Service cost	$ 1,483	$ 932
Interest cost (income)	37	114
Expected return on plan assets	(31)	(97)
Amortization of transition obligation	120	54
Amortization of prior service costs	(21)	(19)
Total net periodic benefit cost	$ 1,588	$ 984
Weighted average assumptions:
Discount rate as of December 31	0.20%	0.20%
Expected long-term rate of return on assets	0.20%	0.20%
Rate of compensation increase	1.00%	1.00%