Benefit Plans (Movements in Other Comprehensive Earnings/Losses) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss, Amortization	$ 187	$ 340	$ 281
Prior service cost/credit	(33)	(35)	(35)
Net loss, Other expense (income)		6	21
Prior service cost/credit, Other expense (income)			(26)
Deferred income taxes	(60)	(120)	(93)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	94	191	148
Net loss, Other movements during the year	(1,411)	1,568	(815)
Prior service cost/credit, Other movements during the year		(9)
Deferred income taxes, Other movements during the year	550	(609)	315
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(861)	950	(500)
Total movements in other comprehensive earnings/losses	(767)	1,141	(352)
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss, Amortization	147	271	224
Prior service cost/credit	10	10	10
Net loss, Other expense (income)		6	21
Prior service cost/credit, Other expense (income)			0
Deferred income taxes	(61)	(111)	(99)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	96	176	156
Net loss, Other movements during the year	(1,093)	1,218	(643)
Prior service cost/credit, Other movements during the year		(7)
Deferred income taxes, Other movements during the year	425	(470)	249
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(668)	741	(394)
Total movements in other comprehensive earnings/losses	(572)	917	(238)
Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss, Amortization	22	51	40
Prior service cost/credit	(43)	(45)	(45)
Net loss, Other expense (income)		0	0
Prior service cost/credit, Other expense (income)			(26)
Deferred income taxes	8	(2)	12
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	(13)	4	(19)
Net loss, Other movements during the year	(306)	327	(161)
Prior service cost/credit, Other movements during the year		(2)
Deferred income taxes, Other movements during the year	120	(129)	63
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(186)	196	(98)
Total movements in other comprehensive earnings/losses	(199)	200	(117)
Postemployment Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss, Amortization	18	18	17
Prior service cost/credit	0	0	0
Net loss, Other expense (income)		0	0
Prior service cost/credit, Other expense (income)			0
Deferred income taxes	(7)	(7)	(6)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	11	11	11
Net loss, Other movements during the year	(12)	23	(11)
Prior service cost/credit, Other movements during the year		0
Deferred income taxes, Other movements during the year	5	(10)	3
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(7)	13	(8)
Total movements in other comprehensive earnings/losses	$ 4	$ 24	$ 3