Retirement Plans and Postretirement Medical Benefits (Benefit Obligations and Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
United States
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,677,288	$ 1,688,982
Projected benefit obligation
Benefit obligation - beginning of year	1,689,885	1,868,176
Service cost	105	134	$ 6,908
Interest cost	73,699	74,331	77,655
Plan participants' contributions	0	0
Actuarial loss (gain)	31,764	(131,179)
Foreign currency changes	0	0
Plan amendments	0	(428)
Settlement / curtailment	(5,887)	(3,678)
Special termination benefits	0	0
Benefits paid	(111,469)	(117,471)
Benefit obligation - end of year	1,678,097	1,689,885	1,868,176
Fair value of plan assets available for benefits
Fair value of plan assets - beginning of year	1,460,790	1,593,463
Actual return on plan assets	110,954	(19,173)
Company contributions	9,694	7,649
Plan participants' contributions	0	0
Settlement / curtailment	(5,887)	(3,678)
Foreign currency changes	0	0
Benefits paid	(111,469)	(117,471)
Fair value of plan assets - end of year	1,464,082	1,460,790	1,593,463
Amounts recognized in the Consolidated Balance Sheets
Noncurrent asset	310	271
Current liability	(7,937)	(9,088)
Noncurrent liability	(206,388)	(220,277)
Funded status	(214,015)	(229,094)
Foreign
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	675,566	635,600
Projected benefit obligation
Benefit obligation - beginning of year	647,112	715,287
Service cost	2,148	2,229	3,565
Interest cost	21,886	24,261	28,518
Plan participants' contributions	6	8
Actuarial loss (gain)	127,054	(15,375)
Foreign currency changes	(88,138)	(53,945)
Plan amendments	0	0
Settlement / curtailment	0	0
Special termination benefits	(423)	79
Benefits paid	(21,473)	(25,432)
Benefit obligation - end of year	688,172	647,112	715,287
Fair value of plan assets available for benefits
Fair value of plan assets - beginning of year	530,112	574,992
Actual return on plan assets	68,067	11,383
Company contributions	40,872	14,194
Plan participants' contributions	6	8
Settlement / curtailment	(423)	0
Foreign currency changes	(69,871)	(45,033)
Benefits paid	(21,473)	(25,432)
Fair value of plan assets - end of year	547,290	530,112	574,992
Amounts recognized in the Consolidated Balance Sheets
Noncurrent asset	11,744	11,566
Current liability	(1,045)	(1,031)
Noncurrent liability	(151,581)	(127,535)
Funded status	(140,882)	(117,000)
Nonpension postretirement benefit plans
Projected benefit obligation
Benefit obligation - beginning of year	211,878	253,980
Service cost	2,046	2,455	2,683
Interest cost	7,969	8,799	9,951
Plan participants' contributions	4,241	4,332
Actuarial loss (gain)	(13,934)	(31,253)
Foreign currency changes	409	(3,289)
Benefits paid	(22,837)	(23,146)
Benefit obligation - end of year	189,772	211,878	253,980
Fair value of plan assets available for benefits
Fair value of plan assets - beginning of year	0	0
Company contributions	18,596	18,814
Plan participants' contributions	4,241	4,332
Benefits paid	(22,837)	(23,146)
Fair value of plan assets - end of year	0	0	$ 0
Amounts recognized in the Consolidated Balance Sheets
Current liability	(18,127)	(19,406)
Noncurrent liability	(171,645)	(192,472)
Funded status	$ (189,772)	$ (211,878)