Pension and Non-pension Postretirement Benefits (Net Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,313	$ 1,909
Interest cost	4,449	4,812
Expected return on plan assets	(5,755)	(6,260)
Amortization of unrecognized:
Prior service cost	12	40
Actuarial loss / (gain)	1,322	2,292
Pension expense or non-pension postretirement benefit expense	1,341	2,793
Defined Benefit Plan, Contributions [Abstract]
Employer contributions made to defined benefit plans	1,500
Estimated employer contributions to defined benefit plans in remainder of 2016	1,000
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	996	1,161
Interest cost	3,777	3,709
Expected return on plan assets	(5,755)	(5,662)
Amortization of unrecognized:
Prior service cost	66	104
Actuarial loss / (gain)	1,120	1,886
Pension expense or non-pension postretirement benefit expense	204	1,198
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	317	748
Interest cost	672	1,103
Expected return on plan assets	0	(598)
Amortization of unrecognized:
Prior service cost	(54)	(64)
Actuarial loss / (gain)	202	406
Pension expense or non-pension postretirement benefit expense	1,137	1,595
Non-Pension Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	199	282
Interest cost	664	679
Amortization of unrecognized:
Prior service cost	35	35
Actuarial loss / (gain)	9	196
Pension expense or non-pension postretirement benefit expense	907	1,192
Defined Benefit Plan, Contributions [Abstract]
Employer contributions made to defined benefit plans	800
Estimated employer contributions to defined benefit plans in year 2016	5,000
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	199	282
Interest cost	652	660
Amortization of unrecognized:
Prior service cost	35	35
Actuarial loss / (gain)	20	196
Pension expense or non-pension postretirement benefit expense	906	1,173
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost	12	19
Amortization of unrecognized:
Prior service cost	0	0
Actuarial loss / (gain)	(11)	0
Pension expense or non-pension postretirement benefit expense	$ 1	$ 19