Pension and Non-pension Postretirement Benefits (Net Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,181	$ 1,784	$ 2,494	$ 3,693
Interest cost	4,375	4,756	8,824	9,568
Expected return on plan assets	(5,760)	(6,306)	(11,515)	(12,566)
Amortization of unrecognized:
Prior service cost	13	44	25	84
Actuarial loss / (gain)	1,219	2,168	2,541	4,460
Settlement Charge	212	0	212	0
Pension expense or non-pension postretirement benefit expense	1,240	2,446	2,581	5,239
Defined Benefit Plan, Contributions [Abstract]
Employer contributions made to defined benefit plans	1,000		2,500
Estimated employer contributions to defined benefit plans in remainder of 2016			1,900
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	863	1,022	1,859	2,183
Interest cost	3,705	3,649	7,482	7,358
Expected return on plan assets	(5,760)	(5,668)	(11,515)	(11,330)
Amortization of unrecognized:
Prior service cost	66	105	132	209
Actuarial loss / (gain)	1,016	1,759	2,136	3,645
Settlement Charge	42	0	42	0
Pension expense or non-pension postretirement benefit expense	(68)	867	136	2,065
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	318	762	635	1,510
Interest cost	670	1,107	1,342	2,210
Expected return on plan assets	0	(638)	0	(1,236)
Amortization of unrecognized:
Prior service cost	(53)	(61)	(107)	(125)
Actuarial loss / (gain)	203	409	405	815
Settlement Charge	170	0	170	0
Pension expense or non-pension postretirement benefit expense	1,308	1,579	2,445	3,174
Non-Pension Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	200	146	399	428
Interest cost	664	619	1,328	1,298
Amortization of unrecognized:
Prior service cost	35	35	70	70
Actuarial loss / (gain)	9	76	18	272
Pension expense or non-pension postretirement benefit expense	908	876	1,815	2,068
Defined Benefit Plan, Contributions [Abstract]
Employer contributions made to defined benefit plans	900		1,700
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	145	398	427
Interest cost	652	609	1,304	1,269
Amortization of unrecognized:
Prior service cost	35	35	70	70
Actuarial loss / (gain)	20	100	40	296
Pension expense or non-pension postretirement benefit expense	906	889	1,812	2,062
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1	1
Interest cost	12	10	24	29
Amortization of unrecognized:
Prior service cost	0	0	0	0
Actuarial loss / (gain)	(11)	(24)	(22)	(24)
Pension expense or non-pension postretirement benefit expense	$ 2	$ (13)	$ 3	$ 6