Retirement Plans and Postretirement Medical Benefits (Components of Net Periodic Benefit Cost for Defined Benefit Pension Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
United States
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 134	$ 6,908	$ 13,981
Interest cost	74,331	77,655	74,370
Expected return on plan assets	(104,004)	(103,822)	(107,608)
Amortization of net transition asset	0	0	0
Amortization of prior service (credit) cost	(60)	9	380
Amortization of net actuarial loss	29,272	25,369	32,494
Special termination benefits	0	0	548
Settlement / curtailment	1,243	4,528	2,638
Net periodic benefit cost (income)	916	10,647	16,803
Foreign
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,229	3,565	6,272
Interest cost	24,261	28,518	27,365
Expected return on plan assets	(35,421)	(39,137)	(34,769)
Amortization of net transition asset	(9)	(10)	(9)
Amortization of prior service (credit) cost	(66)	(57)	112
Amortization of net actuarial loss	5,926	8,268	14,445
Special termination benefits	79	1,238	935
Settlement / curtailment	0	0	0
Net periodic benefit cost (income)	(3,001)	2,385	14,351
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,455	2,683	3,684
Interest cost	8,799	9,951	9,503
Amortization of prior service (credit) cost	297	159	128
Amortization of net actuarial loss	7,528	5,949	7,433
Curtailment	0	0	2,920
Net periodic benefit cost (income)	$ 19,079	$ 18,742	$ 23,668