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, 2016	Dec. 31, 2015	Dec. 31, 2014
United States
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 105	$ 134	$ 6,908
Interest cost	73,699	74,331	77,655
Expected return on plan assets	(101,918)	(104,004)	(103,822)
Amortization of net transition asset	0	0	0
Amortization of prior service (credit) cost	(60)	(60)	9
Amortization of net actuarial loss	27,220	29,272	25,369
Special termination benefits	0	0	0
Settlement / curtailment	2,109	1,243	4,528
Net periodic benefit cost (income)	1,155	916	10,647
Foreign
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,148	2,229	3,565
Interest cost	21,886	24,261	28,518
Expected return on plan assets	(32,615)	(35,421)	(39,137)
Amortization of net transition asset	(8)	(9)	(10)
Amortization of prior service (credit) cost	(73)	(66)	(57)
Amortization of net actuarial loss	5,264	5,926	8,268
Special termination benefits	52	79	1,238
Settlement / curtailment	110	0	0
Net periodic benefit cost (income)	(3,236)	(3,001)	2,385
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,046	2,455	2,683
Interest cost	7,969	8,799	9,951
Amortization of prior service (credit) cost	297	297	159
Amortization of net actuarial loss	3,615	7,528	5,949
Net periodic benefit cost (income)	$ 13,927	$ 19,079	$ 18,742