Employee Benefit Plans - Schedule of Benefit Obligation, Fair Value of Plan Assets, and Funded Status of our Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in Benefit Obligation [Roll Forward]
Service cost	$ 258	$ 270
Interest cost	4,228	5,151
Change in Plan Assets [Roll Forward]
Fair value of plan assets - ending	134,234
Pension Plan, Defined Benefit
Change in Benefit Obligation [Roll Forward]
Benefit obligation - beginning	146,801	145,019
Service cost	258	270
Interest cost	4,228	5,151
Actuarial loss	4,910	29,793
Benefits paid	(4,313)	(6,816)
Currency changes	14,179	(26,616)
Benefit obligation - ending	166,063	146,801
Change in Plan Assets [Roll Forward]
Fair value of plan assets - beginning	118,658	116,386
Employer contribution	2,974	2,105
Actual return on plan assets	5,454	28,422
Benefits paid	(4,313)	(6,816)
Currency changes	11,461	(21,439)
Fair value of plan assets - ending	134,234	118,658
Underfunded status	$ (31,829)	$ (28,143)