Employee Benefit Plans - Pension Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Defined Benefit Plan, Benefit Obligation, Beginning Balance	$ 4,881	$ 5,033	$ 4,881	$ 5,033	$ 4,264
Service cost	243	259
Interest cost	74	71
Actuarial (gains) losses	(202)	(528)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(13)
Adjustment for prior year balance	0	343
Foreign currency translation adjustment	(254)	624
Defined Benefit Plan, Benefit Obligation, Ending Balance	$ 4,881	$ 5,033
Current portion (presented under “Accrued and other current liabilities”)			63	34
Long-term portion (presented under “Other non-current liabilities”)			$ 4,818	$ 4,999