Retirement Plans and Postretirement Medical Benefits (Components of Net Periodic Benefit Cost for Defined Benefit Pension Plans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
United States
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 6,908	$ 13,981	$ 18,939
Interest cost		77,655	74,370	81,040
Expected return on plan assets		(103,822)	(107,608)	(121,623)
Amortization of net transition asset		0	0	0
Amortization of prior service cost (credit)		9	380	803
Amortization of net actuarial loss		25,369	32,494	52,957
Special termination benefits		0	548	0
Settlement / curtailment		4,528	2,638	(48)
Special termination benefits		0	(548)
Net periodic benefit cost		10,647	16,803	32,068
Foreign
Defined Benefit Plan Disclosure [Line Items]
Service cost		3,565	6,272	7,763
Interest cost		28,518	27,365	27,793
Expected return on plan assets		(39,137)	(34,769)	(32,299)
Amortization of net transition asset		(10)	(9)	(10)
Amortization of prior service cost (credit)		(57)	112	112
Amortization of net actuarial loss		8,268	14,445	14,103
Special termination benefits		1,238	935	601
Settlement / curtailment	0	0	0	444
Special termination benefits		(1,238)	(935)
Net periodic benefit cost		2,385	14,351	18,507
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		2,683	3,684	3,563
Interest cost		9,951	9,503	11,187
Amortization of prior service cost (credit)		159	128	(1,724)
Amortization of net actuarial loss		5,949	7,433	8,214
Curtailment		0	2,920	0
Net periodic benefit cost		$ 18,742	$ 23,668	$ 21,240