Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total AOCI ending balance at June 30	$ (7,204)		$ (7,204)		$ (6,959)
Derivative instruments [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	165
Parent Company [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total AOCI ending balance at June 30	(7,204)	$ (6,716)	(7,204)	$ (6,716)
Foreign currency transaction [Abstract]
Beginning balance	(3,981)	(4,350)	(4,277)	(4,593)
Gains/(Losses) on foreign currency translation	(527)	(39)	(283)	150
Less: Tax/(Tax benefit)	69	(123)	19	(177)
Net gains/(losses) on foreign currency translation	(596)	84	(302)	327
(Gains)/Losses reclassified from AOCI to income	0	0	2	0
Other comprehensive income/(loss), net of tax	(596)	84	(300)	327
Ending balance	(4,577)	(4,266)	(4,577)	(4,266)
Marketable securities [Abstract]
Beginning balance	(95)	(15)	(48)	(14)
Gains/(Losses) on available for sale securities	(15)	2	(84)	3
Less: Tax/(Tax benefit)	(4)	2	(21)	5
Net gains/(losses) on available for sale securities	(11)	0	(63)	(2)
(Gains)/Losses reclassified from AOCI to net income	4	4	10	5
Less: Tax/(Tax benefit)	1	0	2	0
Net (gains)/losses reclassified from AOCI to net income	3	4	8	5
Other comprehensive income/(loss), net of tax	(8)	4	(55)	3
Ending balance	(103)	(11)	(103)	(11)
Derivative instruments [Abstract]
Beginning balance	51	116	18	283
Gains/(Losses) on available for sale securities	60	318	121	206
Less: Tax/(Tax benefit)	14	85	29	51
Net gains/(losses) on available for sale securities	46	233	92	155
(Gains)/Losses reclassified from AOCI to net income	12	(124)	(5)	(242)
Less: Tax/(Tax benefit)	6	(28)	2	(57)
Net (gains)/losses reclassified from AOCI to net income	6	(96)	(7)	(185)
Other comprehensive income/(loss), net of tax	52	137	85	(30)
Ending balance	103	253	103	253
Pension and other postretirement benefits
Beginning balance	(2,644)	(2,680)	(2,652)	(2,689)
Amortization of prior service costs/(credits)	14	15	29	30
Less: Tax/(Tax benefit)	3	23	6	28
Net prior service costs/(credits) reclassified from AOCI to net income	11	(8)	23	2
Translation impact on non-U.S. plans	6	(4)	2	(5)
Other comprehensive income/(loss), net of tax	17	(12)	25	(3)
Ending balance	$ (2,627)	$ (2,692)	$ (2,627)	$ (2,692)