Employee Benefit Plans - Pension Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 2,914
Interest cost	1,747	2,151	2,412
Return on plan assets	(2,762)	(2,879)	(3,393)
Amortization of prior service cost	0	0	104
Recognized net actuarial loss	0	743	142
Settlement and curtailment gains	0	(838)	600
Net pension benefit cost (gain)	(1,015)	(823)	2,779
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	6,647
Interest cost	8,179	8,593	9,557
Return on plan assets	(11,914)	(11,764)	(12,389)
Amortization of prior service cost	0	0	118
Recognized net actuarial loss	1,642	1,464	4,398
Settlement and curtailment gains	135	82	200
Net pension benefit cost (gain)	$ (1,958)	$ (1,625)	$ 8,531