Shareholders' Equity (Accumulated other comprehensive income) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balance	[1]	$ (12,748)	$ (13,903)	$ (9,894)
OCI before reclassifications	[1]	(1,434)	(51)	(4,878)
Amounts reclassified from AOCI	[1]	559	1,206	869
Net current period OCI	[1]	(875)	1,155	(4,009)
Balance	[1]	(13,623)	(12,748)	(13,903)
Defined benefit pension plans & other postretirement benefits:
Amortization of actuarial losses included in net periodic pension cost, net of tax of ($570), ($367), and ($849)		524	1,038	661
Amortization of actuarial losses included in net periodic pension cost, tax		(288)	(570)	(367)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balance		(39)	53	150
OCI before reclassifications		(104)	(92)	(97)
Amounts reclassified from AOCI
Net current period OCI		(104)	(92)	(97)
Balance		(143)	(39)	53
Unrealized Gains and Losses on Certain Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balance		0	(8)	(8)
OCI before reclassifications		(2)	8
Amounts reclassified from AOCI
Net current period OCI		(2)	8
Balance		(2)	0	(8)
Unrealized Gains and Losses on Derivative Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balance		(197)	(136)	(6)
OCI before reclassifications		(8)	(140)	(137)
Amounts reclassified from AOCI		78	79	7
Net current period OCI		70	(61)	(130)
Balance		(127)	(197)	(136)
Defined Benefit Pension Plans and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Balance		(12,512)	(13,812)	(10,030)
OCI before reclassifications		(1,320)	173	(4,644)
Amounts reclassified from AOCI	[2]	481	1,127	862
Net current period OCI		(839)	1,300	(3,782)
Balance		$ (13,351)	$ (12,512)	$ (13,812)

[1] Net of tax.

[2] Primarily relates to amortization of actuarial losses for the years ended December 31, 2016, 2015, and 2014 totaling $524, $1,038, and $661 (net of tax of ($288), ($570), and ($367)), respectively. These are included in the net periodic pension cost of which a portion is allocated to production as inventoried costs. See Note 14.