Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 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	$ 4,319	$ 4,983	$ 12,934	$ 14,856
Interest cost on projected benefit obligations	3,575	5,196	11,438	15,550
Expected return on plan assets	(10,045)	(11,623)	(30,932)	(35,050)
Net amortization and deferral	(1,757)	(2,144)	(5,264)	(5,040)
Recognition of actuarial losses/(gains)	5,753	4,819	17,265	14,585
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments			7,963	0
Net periodic pension cost/(credit)	1,845	1,231	13,404	4,901
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	103	211	328	628
Interest cost on projected benefit obligations	1,014	1,607	3,414	4,823
Expected return on plan assets	(1,868)	(2,395)	(5,912)	(7,183)
Net amortization and deferral	0	0	0	0
Recognition of actuarial losses/(gains)	1,907	1,906	5,699	5,720
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments			7,963	0
Net periodic pension cost/(credit)	1,156	1,329	11,492	3,988
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	4,216	4,772	12,606	14,228
Interest cost on projected benefit obligations	2,542	3,554	7,967	10,623
Expected return on plan assets	(8,177)	(9,228)	(25,020)	(27,867)
Net amortization and deferral	(1,288)	(1,675)	(3,856)	(3,632)
Recognition of actuarial losses/(gains)	4,519	3,756	13,585	11,393
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments			0	0
Net periodic pension cost/(credit)	1,812	1,179	5,282	4,745
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	57	104
Expected return on plan assets	0	0	0	0
Net amortization and deferral	(469)	(469)	(1,408)	(1,408)
Recognition of actuarial losses/(gains)	(673)	(843)	(2,019)	(2,528)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments			0	0
Net periodic pension cost/(credit)	$ (1,123)	$ (1,277)	(3,370)	$ (3,832)
Net Periodic Benefit Cost (Textuals) [Abstract]
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			$ 500