Retirement Plans and Postretirement Medical Benefits (Benefit Obligations and Funded Status) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
United States
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,866,914		$ 1,611,457
Projected benefit obligation
Benefit obligation - beginning of year	1,622,591		1,822,677
Service cost	6,908		13,981		18,939
Interest cost	77,655		74,370		81,040
Plan participants' contributions	0		0
Actuarial loss (gain)	306,718		(154,996)
Foreign currency changes	0		0
Settlement / curtailment	(16,867)		(3,275)
Special termination benefits	0		548
Benefits paid	(128,829)		(130,714)
Benefit obligation - end of year	1,868,176		1,622,591		1,822,677
Fair value of plan assets available for benefits
Fair value of plan assets - beginning of year	1,523,679		1,583,932
Actual return on plan assets	195,946		60,569
Company contributions	19,534		9,892
Plan participants' contributions	0		0
Settlement / curtailment	(16,867)		0
Foreign currency changes	0		0
Benefits paid	(128,829)		(130,714)
Fair value of plan assets - end of year	1,593,463		1,523,679		1,583,932
Funded status	(274,713)		(98,912)
Non-current asset	300		195
Current liability	(6,590)		(18,097)
Non-current liability	(268,423)		(81,010)
Net amount recognized	(274,713)		(98,912)
Foreign
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	698,176		659,602
Projected benefit obligation
Benefit obligation - beginning of year	672,773		663,826
Service cost	3,565		6,272		7,763
Interest cost	28,518		27,365		27,793
Plan participants' contributions	59		496
Actuarial loss (gain)	89,695		(1,224)
Foreign currency changes	(52,750)		(204)
Settlement / curtailment	0		(86)
Special termination benefits	1,238		935
Benefits paid	(27,811)		(24,607)
Benefit obligation - end of year	715,287		672,773		663,826
Fair value of plan assets available for benefits
Fair value of plan assets - beginning of year	561,078		509,331
Actual return on plan assets	67,306		62,777
Company contributions	15,323		14,509
Plan participants' contributions	59		496
Settlement / curtailment	0		0
Foreign currency changes	(40,963)		(1,428)
Benefits paid	(27,811)		(24,607)
Fair value of plan assets - end of year	574,992		561,078		509,331
Funded status	(140,295)		(111,695)
Non-current asset	5,813		11,951
Current liability	(1,008)		(1,051)
Non-current liability	(145,100)		(122,595)
Net amount recognized	(140,295)		(111,695)
Nonpension postretirement benefit plans
Projected benefit obligation
Benefit obligation - beginning of year	231,153	[1]	282,857
Service cost	2,683		3,684		3,563
Interest cost	9,951		9,503		11,187
Plan participants' contributions	5,418		4,313
Actuarial loss (gain)	37,532		(30,051)
Foreign currency changes	(2,096)		(1,693)
Settlement / curtailment	(2,160)		(4,839)
Benefits paid	(28,501)		(32,621)
Benefit obligation - end of year	253,980	[1]	231,153	[1]	282,857
Fair value of plan assets available for benefits
Fair value of plan assets - beginning of year	0		0
Company contributions	23,083		28,308
Plan participants' contributions	5,418		4,313
Benefits paid	(28,501)		(32,621)
Fair value of plan assets - end of year	0		0		0
Funded status	(253,980)		(231,153)
Current liability	(22,113)		(23,668)
Non-current liability	(231,867)		(207,485)
Net amount recognized	$ (253,980)		$ (231,153)

[1] Fair value of plan assets Fair value of plan assets - beginning of year$— $—Company contribution23,083 28,308Plan participants' contributions5,418 4,313Benefits paid(28,501) (32,621)Fair value of plan assets - end of year$— $—