Shareholders' Equity (Accumulated other comprehensive income) (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (13,420)		$ (8,659)		$ (13,903)	$ (9,894)
OCI before reclassifications	[1]	(134)		(161)		(209)	527
Amounts reclassified from AOCI	[1]	291		167		849	714
Net current period Other comprehensive income/(loss)	[1]	157		6		640	1,241
Ending Balance	[1]	(13,263)		(8,653)		(13,263)	(8,653)
OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForSettlementsAndCurtailmentsAndNetGainLossNetOfTax		257		165		768	700
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for for settlements, curtailments and net (gain) loss, Tax		(143)		(90)		(427)	(388)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		9		188		53	150
OCI before reclassifications		$ (35)		$ (72)		$ (79)	$ (34)
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		$ (35)		$ (72)		$ (79)	$ (34)
Ending Balance		(26)		116		(26)	116
Unrealized Gains and Losses on Certain Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(4)		(5)		(8)	(8)
OCI before reclassifications		$ 1		$ (1)		$ 5	$ 2
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		$ 1		$ (1)		$ 5	$ 2
Ending Balance		(3)		(6)		(3)	(6)
Unrealized Gains and Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(174)		20		(136)	(6)
OCI before reclassifications		(73)		(89)		(139)	(64)
Amounts reclassified from AOCI		24		(3)		52	(2)
Net current period Other comprehensive income/(loss)		(49)		(92)		(87)	(66)
Ending Balance		(223)		(72)		(223)	(72)
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(13,251)		(8,862)		(13,812)	(10,030)
OCI before reclassifications		(27)		1		4	623
Amounts reclassified from AOCI		267	[2]	170	[2]	797	716
Net current period Other comprehensive income/(loss)		240		171		801	1,339
Ending Balance		$ (13,011)		$ (8,691)		$ (13,011)	$ (8,691)

[1] Net of tax.

[2] Primarily relates to amortization of actuarial gains/losses, settlements, and curtailments for the nine months ended September 30, 2014 totaling $700 (net of tax of $(388)) and to amortization of actuarial gains/losses for the three months ended September 30, 2014 totaling $165 (net of tax of $(90)) and the nine and three months ended September 30, 2015 totaling $768 and $257 (net of tax of $(427) and $(143)). These are included in the net periodic pension cost of which a portion is allocated to production as inventoried costs. See Note 12.