Retirement Plans and Postretirement Medical Benefits (Other Changes in Plan Assets and Benefit Obligations) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
United States
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss		$ (8,003)	$ 214,593
Prior service credit		(428)	0
Amortization of net actuarial loss		(29,272)	(25,369)
Amortization of prior service credit (cost)		60	(9)
Net transition asset		0	0
Settlement / curtailment		(1,243)	(4,528)
Total recognized in other comprehensive income		(38,886)	184,687
Foreign
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss		8,663	61,525
Prior service credit		0	0
Amortization of net actuarial loss		(5,926)	(8,268)
Amortization of prior service credit (cost)		66	57
Net transition asset		9	10
Settlement / curtailment	$ 0	0
Total recognized in other comprehensive income		2,812	53,324
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss		(31,253)	37,532
Amortization of net actuarial loss		(7,528)	(5,949)
Amortization of prior service credit (cost)		(297)	(159)
Settlement / curtailment		$ 0	(2,160)
Other adjustments			412
Total recognized in other comprehensive income		$ (39,078)	$ 29,676