Employee Benefit Obligations - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net Periodic Benefit Cost
Service cost	$ 932	$ 820
Interest cost (income)	114	69
Expected return on plan assets	(97)	(54)
Amortization of transition obligation	54	65
Amortization of prior service costs	(19)	(18)
Total net periodic benefit cost	$ 984	$ 882
Weighted average assumptions:
Discount rate as of December 31	0.20%	0.90%
Expected long-term rate of return on assets	0.20%	0.90%
Rate of compensation increase	1.00%	1.00%