Shareholders' Equity (Accumulated other comprehensive income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (8,659)	[1]	$ (16,794)	[1]	$ (9,894)	[1]	$ (17,416)	[1]
OCI before reclassifications	(161)	[1]	179	[1]	527	[1]	35	[1]
Amounts reclassified from AOCI	167	[1]	428	[1]	714	[1]	1,194	[1]
Net current period Other comprehensive income/(loss)	6	[1]	607	[1]	1,241	[1]	1,229	[1]
Ending Balance	(8,653)	[1]	(16,187)	[1]	(8,653)	[1]	(16,187)	[1]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss, Net of Tax	165		380		498		1,135
Amortization of actuarial losses included in net periodic pension cost, tax	(90)		(213)		(275)		(644)
Settlements, curtailments and amortization of actuarial gains/losses included in net periodic pension cost, net of tax	165				700
Settlements, curtailments and amortization of actuarial gains/losses included in net periodic pension cost, tax	(90)				(388)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	188		126		150		214
OCI before reclassifications	(72)		42		(34)		(46)
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)	(72)		42		(34)		(46)
Ending Balance	116		168		116		168
Unrealized Gains and Losses on Certain Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5)		(8)		(8)		(8)
OCI before reclassifications	(1)				2
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)	(1)				2
Ending Balance	(6)		(8)		(6)		(8)
Unrealized Gains and Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	20		(6)		(6)		86
OCI before reclassifications	(89)		35		(64)		(54)
Amounts reclassified from AOCI	(3)		(10)		(2)		(13)
Net current period Other comprehensive income/(loss)	(92)		25		(66)		(67)
Ending Balance	(72)		19		(72)		19
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(8,862)		(16,906)		(10,030)		(17,708)
OCI before reclassifications	1		102		623		135
Amounts reclassified from AOCI	170	[2]	438	[2]	716	[2]	1,207	[2]
Net current period Other comprehensive income/(loss)	171		540		1,339		1,342
Ending Balance	$ (8,691)		$ (16,366)		$ (8,691)		$ (16,366)

[1] Net of tax.

[2] Primarily relates to amortization of actuarial gains/losses for the nine and three months ended September 30, 2013 totaling $1,135 and $380 (net of tax of $(644) and $(213)) and to amortization of actuarial gains/losses, settlements and curtailments for the nine and three months ended September 30, 2014 totaling $700 and $165 (net of tax of ($388) and $(90)). These are included in the net periodic pension cost of which a portion is allocated to production as inventoried costs.