Pension and Non-pension Postretirement Benefits (Net Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,242	$ 1,832	$ 3,736	$ 5,525
Interest cost	4,403	4,763	13,227	14,331
Expected return on plan assets	(5,757)	(6,274)	(17,272)	(18,840)
Amortization of unrecognized:
Prior service cost	12	42	37	126
Actuarial loss / (gain)	1,480	2,223	4,021	6,683
Settlement Charge			212	0
Pension expense or non-pension postretirement benefit expense	1,380	2,586	3,961	7,825
Defined Benefit Plan, Contributions [Abstract]
Employer contributions made to defined benefit plans	700		3,100
Estimated employer contributions to defined benefit plans in remainder of 2016			1,200
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	929	1,091	2,788	3,274
Interest cost	3,740	3,678	11,222	11,036
Expected return on plan assets	(5,757)	(5,666)	(17,272)	(16,996)
Amortization of unrecognized:
Prior service cost	65	104	197	313
Actuarial loss / (gain)	1,068	1,823	3,204	5,468
Settlement Charge			42	0
Pension expense or non-pension postretirement benefit expense	45	1,030	181	3,095
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	313	741	948	2,251
Interest cost	663	1,085	2,005	3,295
Expected return on plan assets	0	(608)	0	(1,844)
Amortization of unrecognized:
Prior service cost	(53)	(62)	(160)	(187)
Actuarial loss / (gain)	412	400	817	1,215
Settlement Charge			170	0
Pension expense or non-pension postretirement benefit expense	1,335	1,556	3,780	4,730
Non-Pension Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	200	214	599	642
Interest cost	663	644	1,991	1,942
Amortization of unrecognized:
Prior service cost	35	35	105	105
Actuarial loss / (gain)	11	129	29	401
Pension expense or non-pension postretirement benefit expense	909	1,022	2,724	3,090
Defined Benefit Plan, Contributions [Abstract]
Employer contributions made to defined benefit plans	900		2,700
Estimated employer contributions to defined benefit plans in year 2016			4,000
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	200	214	598	641
Interest cost	652	634	1,956	1,903
Amortization of unrecognized:
Prior service cost	35	35	105	105
Actuarial loss / (gain)	21	148	61	444
Pension expense or non-pension postretirement benefit expense	908	1,031	2,720	3,093
Non-U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	11	10	35	39
Amortization of unrecognized:
Prior service cost	0	0	0	0
Actuarial loss / (gain)	(10)	(19)	(32)	(43)
Pension expense or non-pension postretirement benefit expense	$ 1	$ (9)	$ 4	$ (3)