Shareowners' Equity and Noncontrolling Interest (Summary of Changes in AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (7,327)	$ (7,729)	$ (7,327)	$ (7,729)	$ (7,964)	$ (8,334)	$ (7,484)	$ (7,619)
Other comprehensive (loss) income before reclassifications, net - Foreign Currency Translation	514	(359)	909	(596)
Amounts reclassified, pretax - Foreign Currency Translation	3	1	3	0
Tax (benefit) expense reclassified - Foreign Currency Translation	0	0	0	0
Other comprehensive (loss) income before reclassifications, net - Pension	37	(4)	39	21
Amounts reclassified, pretax - Pension	132	127	395	381
Tax (benefit) expense reclassified - Pension	66	47	164	140
Other comprehensive (loss) income before reclassifications, net - AFS Securities	12	30	11	87
Amounts reclassified, pretax - AFS Securities	138	20	545	72
Tax (benefit) expense reclassified - AFS Securities	50	8	205	27
Other comprehensive (loss) income before reclassifications, net - Unrealized Hedging (Losses) Gains	232	(5)	332	138
Amounts reclassified, pretax - Unrealized Hedging (Losses) Gains	24	(32)	14	(139)
Tax (benefit) expense reclassified - Unrealized Hedging (Losses) Gains	5	(9)	3	(37)
Other comprehensive (loss) income before reclassifications, net	681	(335)	1,130	(408)
Amounts reclassified, pretax	33	(138)	167	(448)
Tax (benefit) expense reclassified	(11)	(48)	44	(150)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(2,657)	(3,050)	(2,657)	(3,050)	(3,128)	(3,480)	(2,685)	(2,438)
Other comprehensive (loss) income before reclassifications, net - Foreign Currency Translation	474	(364)	826	(612)
Defined Benefit Pension and Post-retirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(4,853)	(4,915)	(4,853)	(4,915)	(4,882)	(5,045)	(4,999)	(5,135)
Unrealized Gains (Losses) on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	24	335	24	335	100	353	317	293
Unrealized Hedging (Losses) Gains
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 159	$ (99)	159	$ (99)	$ (54)	$ (162)	$ (117)	$ (339)
Sales of significant investments in AFS securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified, pretax - Unrealized Hedging (Losses) Gains			$ 500