Retirement Plans and Postretirement Medical Benefits (Pretax Amounts Recognized in AOCI) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
United States
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 873,523	$ 880,123
Prior service credit	(452)	(512)
Transition asset	0	0
Total	873,071	879,611
Foreign
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	342,169	255,994
Prior service credit	(667)	(740)
Transition asset	(32)	(40)
Total	341,470	255,214
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	41,625	59,174
Prior service credit	1,763	2,060
Total	$ 43,388	$ 61,234