Shareholders' Equity (Accumulated other comprehensive income) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (12,748)	$ (13,903)
OCI before reclassifications	[1]	(241)	(178)
Amounts reclassified from AOCI	[1]	151	266
Net current period Other comprehensive income/(loss)	[1]	(90)	88
Ending Balance	[1]	(12,838)	(13,815)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax		131	244
Amortization of actuarial losses included in net periodic pension cost, tax		(72)	(137)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(39)	53
OCI before reclassifications		$ 23	$ (88)
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		$ 23	$ (88)
Ending Balance		$ (16)	(35)
Unrealized Gains and Losses on Certain Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(8)
OCI before reclassifications		$ (2)	$ 1
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		$ (2)	$ 1
Ending Balance		(2)	(7)
Unrealized Gains and Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(197)	(136)
OCI before reclassifications		58	(91)
Amounts reclassified from AOCI		23	12
Net current period Other comprehensive income/(loss)		81	(79)
Ending Balance		(116)	(215)
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(12,512)	$ (13,812)
OCI before reclassifications		(320)
Amounts reclassified from AOCI	[2]	128	$ 254
Net current period Other comprehensive income/(loss)		(192)	254
Ending Balance		$ (12,704)	$ (13,558)

[1] Net of tax.

[2] Primarily relates to amortization of actuarial gains/losses for the three months ended March 31, 2016 and 2015 totaling $131 and $244 (net of tax of $(72) and $(137)). These are included in the net periodic pension cost of which a portion is allocated to production as inventoried costs. See Note 10.