Employee Benefit Plans - Pension Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Non-US
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0
Interest cost	1,814	1,747	2,151
Return on plan assets	(2,471)	(2,762)	(2,879)
Amortization of prior service cost	10	0	0
Recognized net actuarial loss	0	0	743
Settlement and curtailment gains	0	0	(838)
Net pension benefit cost (gain)	(647)	(1,015)	(823)
US plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost	8,711	8,179	8,593
Return on plan assets	(10,313)	(11,914)	(11,764)
Amortization of prior service cost	0	0	0
Recognized net actuarial loss	2,771	1,642	1,464
Settlement and curtailment gains	(37)	135	82
Net pension benefit cost (gain)	$ 1,132	$ (1,958)	$ (1,625)