Shareholders' Equity (Accumulated other comprehensive income) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (13,415)	$ (12,838)	$ (13,623)	$ (12,748)
OCI before reclassifications	[1]	61	(97)	149	(338)
Amounts reclassified from AOCI	[1]	120	140	240	291
Net current period Other comprehensive income/(loss)	[1]	181	43	389	(47)
Ending Balance	[1]	(13,234)	(12,795)	(13,234)	(12,795)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax		131	130	263	261
Amortization of actuarial losses included in net periodic pension cost, tax		(73)	(73)	(145)	(145)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(109)	(16)	(143)	(39)
OCI before reclassifications		43	(16)	77	7
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		43	(16)	77	7
Ending Balance		(66)	(32)	(66)	(32)
Unrealized Gains and Losses on Certain Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(1)	(2)	(2)
OCI before reclassifications		(1)	1		(1)
Amounts reclassified from AOCI
Net current period Other comprehensive income/(loss)		(1)	1		(1)
Ending Balance		(2)	(1)	(2)	(1)
Unrealized Gains and Losses on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(59)	(116)	(127)	(197)
OCI before reclassifications		19	(17)	71	41
Amounts reclassified from AOCI		18	20	34	43
Net current period Other comprehensive income/(loss)		37	3	105	84
Ending Balance		(22)	(113)	(22)	(113)
Defined Benefit Pension Plans and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(13,246)	(12,704)	(13,351)	(12,512)
OCI before reclassifications			(65)	1	(385)
Amounts reclassified from AOCI	[2]	102	120	206	248
Net current period Other comprehensive income/(loss)		102	55	207	(137)
Ending Balance		$ (13,144)	$ (12,649)	$ (13,144)	$ (12,649)

[1] Net of tax.

[2] Primarily relates to amortization of actuarial losses for the six and three months ended June 30, 2016 totaling $261 and $130 (net of tax of ($145) and ($73)) and for the six and three months ended June 30, 2017 totaling $263 and $131 (net of tax of ($145) and ($73)). These are included in the net periodic pension cost of which a portion is allocated to production as inventoried costs. See Note 17.