Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total AOCI ending balance at March 31	$ (7,501)		$ (7,366)
Derivative instruments [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	(145)
Parent Company [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total AOCI ending balance at March 31	(7,501)	$ (6,669)
Foreign currency transaction [Abstract]
Beginning balance	(4,800)	(4,277)
Gains/(Losses) on foreign currency translation	271	244
Less: Tax/(Tax benefit)	28	(50)
Net gains/(losses) on foreign currency translation	243	294
(Gains)/Losses reclassified from AOCI to income	0	2
Other comprehensive income/(loss), net of tax	243	296
Ending balance	(4,557)	(3,981)
Marketable securities [Abstract]
Beginning balance	(59)	(48)
Gains/(Losses) on available for sale securities	80	(69)
Less: Tax/(Tax benefit)	19	(17)
Net gains/(losses) on available for sale securities	61	(52)
(Gains)/Losses reclassified from AOCI to net income	3	6
Less: Tax/(Tax benefit)	1	1
Net (gains)/losses reclassified from AOCI to net income	2	5
Other comprehensive income/(loss), net of tax	63	(47)
Ending balance	4	(95)
Derivative instruments [Abstract]
Beginning balance	201	18
Gains/(Losses) on available for sale securities	(510)	61
Less: Tax/(Tax benefit)	(102)	15
Net gains/(losses) on available for sale securities	(408)	46
(Gains)/Losses reclassified from AOCI to net income	(49)	(17)
Less: Tax/(Tax benefit)	(11)	(4)
Net (gains)/losses reclassified from AOCI to net income	(38)	(13)
Other comprehensive income/(loss), net of tax	(446)	33
Ending balance	(245)	51
Pension and other postretirement benefits
Beginning balance	(2,708)	(2,652)
Amortization of prior service costs/(credits)	12	15
Less: Tax/(Tax benefit)	2	3
Net prior service costs/(credits) reclassified from AOCI to net income	10	12
Translation impact on non-U.S. plans	(5)	(4)
Other comprehensive income/(loss), net of tax	5	8
Ending balance	$ (2,703)	$ (2,644)