Retirement Plans and Postretirement Medical Benefits (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Eligibility age for retiree medical benefits	55 years
Percent of all foreign plan assets	75.00%
Fair value of plan assets	$ 399,000		$ 427,000
Expected return on plan assets	7.00%		7.50%
Assumed health care cost trend rate	6.00%		6.50%
Next year's assumed health care cost trend rate	6.00%
Assumed health care cost trend rate decline	5.00%
Total contributions to defined contribution plans	$ 28,000		$ 25,000
United States
Defined Benefit Plan Disclosure [Line Items]
Next year's anticipated total contributions to pension plans	$ 9,000
Nominal rate of return	7.00%
Fair value of plan assets	$ 1,460,111		$ 1,592,774
Expected return on plan assets	7.00%		7.00%		7.25%
Benefit obligation	$ 1,689,885		$ 1,868,176		$ 1,622,591
Foreign
Defined Benefit Plan Disclosure [Line Items]
Next year's anticipated total contributions to pension plans	$ 46,000
Nominal rate of return	6.50%
Fair value of plan assets	$ 412,418		437,209
Benefit obligation	647,112		715,287		672,773
U.S. nonpension postretirement plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	198,000		231,000
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	$ 211,878	[1]	$ 253,980	[1]	$ 231,153

[1] The benefit obligation for the U.S. nonpension postretirement plans was $198 million and $231 million at December 31, 2015 and 2014, respectively.