Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Components of Net periodic pension cost for the Company's defined benefit pension plans and U.S. post-retirement medical plan
Service cost, net	$ 4,298	$ 4,919	$ 8,645	$ 9,873
Interest cost on projected benefit obligations	3,764	5,158	7,747	10,354
Expected return on plan assets	(10,286)	(11,734)	(20,725)	(23,427)
Net amortization and deferral	(1,747)	(1,453)	(3,494)	(2,895)
Recognition of actuarial losses/(gains)	5,792	4,881	11,499	9,764
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	7,963	0	7,963	0
Net periodic pension cost/(credit)	9,784	1,771	11,635	3,669
Net Periodic Benefit Cost (Textuals) [Abstract]
Defined Benefit Plan, Settlements, Benefit Obligation			14,600
Other Comprehensive Income (Loss), Finalization of Pension and Other Postretirement Benefit Plan Valuation, before Tax			(8,189)	0
Defined Benefit Plan, Settlement Loss after tax			4,900
United States Pension Plans of US Entity, Defined Benefit [Member]
Components of Net periodic pension cost for the Company's defined benefit pension plans and U.S. post-retirement medical plan
Service cost, net	145	208	262	417
Interest cost on projected benefit obligations	1,072	1,608	2,364	3,216
Expected return on plan assets	(1,945)	(2,394)	(4,044)	(4,788)
Net amortization and deferral	0	0	0	0
Recognition of actuarial losses/(gains)	1,902	1,907	3,792	3,814
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	7,963	0	7,963	0
Net periodic pension cost/(credit)	9,137	1,329	10,337	2,659
Foreign Pension Plans, Defined Benefit [Member]
Components of Net periodic pension cost for the Company's defined benefit pension plans and U.S. post-retirement medical plan
Service cost, net	4,153	4,711	8,383	9,456
Interest cost on projected benefit obligations	2,673	3,515	5,345	7,069
Expected return on plan assets	(8,341)	(9,340)	(16,681)	(18,639)
Net amortization and deferral	(1,278)	(984)	(2,556)	(1,957)
Recognition of actuarial losses/(gains)	4,563	3,817	9,053	7,635
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	0	0	0	0
Net periodic pension cost/(credit)	1,770	1,719	3,544	3,564
Net Periodic Benefit Cost (Textuals) [Abstract]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			19,400
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Components of Net periodic pension cost for the Company's defined benefit pension plans and U.S. post-retirement medical plan
Service cost, net	0	0	0	0
Interest cost on projected benefit obligations	19	35	38	69
Expected return on plan assets	0	0	0	0
Net amortization and deferral	(469)	(469)	(938)	(938)
Recognition of actuarial losses/(gains)	(673)	(843)	(1,346)	(1,685)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	0	0	0	0
Net periodic pension cost/(credit)	$ (1,123)	$ (1,277)	(2,246)	$ (2,554)
Net Periodic Benefit Cost (Textuals) [Abstract]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			$ 500