Shareholders' Equity (Accumulated other comprehensive income) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (12,795)	$ (13,420)	$ (12,748)	$ (13,903)
OCI before reclassifications	[1]	6	(134)	(332)	(209)
Amounts reclassified from AOCI	[1]	131	291	422	849
Net current period Other comprehensive income/(loss)	[1]	137	157	90	640
Ending Balance	[1]	(12,658)	(13,263)	(12,658)	(13,263)
Other Comprehensive Income Loss Reclassification Adjustment From AOCI Pension And Other Postretirement Benefit Plans For Settlements And Curtailments And Net Gain Loss Net Of Tax			257		768
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for for settlements, curtailments and net (gain) loss, Tax			(143)		(427)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax		131	257	392	765
Amortization of actuarial losses included in net periodic pension cost, tax		(72)	(143)	(217)	(425)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(32)	9	(39)	53
OCI before reclassifications		(10)	(35)	(3)	(79)
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		(10)	(35)	(3)	(79)
Ending Balance		(42)	(26)	(42)	(26)
Unrealized Gains and Losses on Certain Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(1)	(4)		(8)
OCI before reclassifications		2	1	1	5
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		2	1	1	5
Ending Balance		1	(3)	1	(3)
Unrealized Gains and Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(113)	(174)	(197)	(136)
OCI before reclassifications		13	(73)	54	(139)
Amounts reclassified from AOCI		15	24	58	52
Net current period Other comprehensive income/(loss)		28	(49)	112	(87)
Ending Balance		(85)	(223)	(85)	(223)
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(12,649)	(13,251)	(12,512)	(13,812)
OCI before reclassifications		1	(27)	(384)	4
Amounts reclassified from AOCI	[2]	116	267	364	797
Net current period Other comprehensive income/(loss)		117	240	(20)	801
Ending Balance		$ (12,532)	$ (13,011)	$ (12,532)	$ (13,011)

[1] Net of tax.

[2] Primarily relates to amortization of actuarial losses for the nine months and three months ended September 30, 2015 totaling $768 and $257 (net of tax of ($427) and ($143)) and for the nine and three months ended September 30, 2016 totaling $392 and $131 (net of tax of ($217) and ($72)). These are included in the net periodic pension cost of which a portion is allocated to production as inventoried costs. See Note 11.