Other Employee Benefit Plans (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Change in benefit obligation:
Benefit obligation at January 1	$ 10,149	$ 11,419
Service costs	0	0	$ 0
Interest costs	96	386	397
Actuarial loss (gain)	22	(1,720)
Benefits paid	6,230	310
Foreign currency exchange changes	(327)	374
Benefit obligation at December 31	3,710	10,149	$ 11,419
Fair value of plan assets at December 31	0	0
Unfunded status at December 31	3,710	10,149
Amounts recognized in the Consolidated Balance Sheets:
Current liabilities	293	6,262
Non-current liabilities	$ 3,417	$ 3,887		$ 51,842
Supplemental Executive Retirement Plan (SERP)
Net periodic benefit cost:
Discount rate	2.75%	4.00%
Rate of increase in compensation levels		3.00%
Funded status and projected benefit obligation:
Discount rate	3.40%	2.75%
Defined benefit pension plan for employees outside the United States
Change in benefit obligation:
Actuarial loss (gain)	$ 600	$ 1,700
Net periodic benefit cost:
Discount rate	1.75%	2.00%
Funded status and projected benefit obligation:
Discount rate	1.75%	1.75%