Pension and Severance Plans (Changes and Components) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 33,854	$ 12,481
Interest cost	3,641	2,954
Recognized actuarial (gain) loss	2,801	2,631
Foreign Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	33,854	12,481	$ 5,042
Interest cost	3,641	2,954	3,051
Expected return on plan assets	(3,788)	(3,330)	(3,094)
Amortization of prior service cost	35	34	116
Recognized actuarial (gain) loss	94	91	141
Net periodic pension cost	33,836	12,230	5,256
Settlement (gain) loss	128	27	97
Total pension expense	$ 33,964	$ 12,257	$ 5,353