Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Derivative instruments [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			$ (304)
Pension and other postretirement benefits
Total AOCI ending balance at June 30	$ (8,268)		(8,268)		$ (8,294)
Parent Company [Member]
Foreign currency transaction [Abstract]
Beginning balance	(5,237)	$ (6,079)	(5,526)	$ (4,626)
Gains/(Losses) on foreign currency translation	(46)	(141)	348	(1,547)
Less: Tax/(Tax benefit)	(30)	(50)	67	(23)
Net gains/(losses) on foreign currency translation	(16)	(91)	281	(1,524)
(Gains)/Losses reclassified from AOCI to income	4	(11)	(4)	(31)
Other comprehensive income/(loss), net of tax (b)	(12)	(102)	277	(1,555)
Ending balance	(5,249)	(6,181)	(5,249)	(6,181)
Marketable securities [Abstract]
Beginning balance	91	85	156	71
Gains/(Losses) on available for sale securities	(10)	146	(86)	165
Less: Tax/(Tax benefit)	(3)	33	(22)	38
Net gains/(losses) on available for sale securities	(7)	113	(64)	127
(Gains)/Losses reclassified from AOCI to net income	(4)	(18)	(15)	(18)
Less: Tax/(Tax benefit)	(1)	(4)	(4)	(4)
Net (gains)/losses reclassified from AOCI to net income	(3)	(14)	(11)	(14)
Other comprehensive income/(loss), net of tax	(10)	99	(75)	113
Ending balance	81	184	81	184
Derivative instruments [Abstract]
Beginning balance	(567)	204	(266)	(488)
Gains/(Losses) on available for sale securities	(10)	(64)	(391)	732
Less: Tax/(Tax benefit)	(3)	(23)	(77)	150
Net gains/(losses) on available for sale securities	(7)	(41)	(314)	582
(Gains)/Losses reclassified from AOCI to net income	153	18	160	102
Less: Tax/(Tax benefit)	34	1	35	16
Net (gains)/losses reclassified from AOCI to net income	119	17	125	86
Other comprehensive income/(loss), net of tax	112	(24)	(189)	668
Ending balance	(455)	180	(455)	180
Pension and other postretirement benefits
Beginning balance	(2,657)	(2,671)	(2,658)	(2,685)
Amortization of prior service costs/(credits)	17	22	20	26
Less: Tax/(Tax benefit)	3	3	4	4
Net prior service costs/(credits) reclassified from AOCI to net income	14	19	16	22
Translation impact on non-U.S. plans	(2)	(2)	(3)	9
Other comprehensive income/(loss), net of tax	12	17	13	31
Ending balance	(2,645)	(2,654)	(2,645)	(2,654)
Total AOCI ending balance at June 30	$ (8,268)	$ (8,471)	(8,268)	$ (8,471)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest			$ 2