Financial Instruments (Effect of Derivative Instruments on Income and Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Derivatives in Net Investment Hedging Relationship:
Revenues	$ 41,159	$ 36,339
Other income (expense), net	(220)	1,538
Revenues
Foreign exchange contracts
Total gains (losses)	49	137
Other income (expense), net
Foreign exchange contracts
Total gains (losses)	280	(185)
Foreign exchange contracts
Derivatives in Net Investment Hedging Relationship:
Total	544	28
Foreign exchange contracts \| Revenues \| Fair Value of Derivatives Not Designated as Hedging Instruments
Foreign exchange contracts
Derivatives not designated as hedging instruments	0	0
Foreign exchange contracts \| Other income (expense), net \| Fair Value of Derivatives Not Designated as Hedging Instruments
Foreign exchange contracts
Derivatives not designated as hedging instruments	229	(249)
Other derivatives \| Revenues \| Fair Value of Derivatives Not Designated as Hedging Instruments
Foreign exchange contracts
Derivatives not designated as hedging instruments	0	0
Other derivatives \| Other income (expense), net \| Fair Value of Derivatives Not Designated as Hedging Instruments
Foreign exchange contracts
Derivatives not designated as hedging instruments	(28)	0
Derivatives in Cash Flow Hedging Relationship \| Foreign exchange contracts
Derivatives in Cash Flow Hedging Relationship:
Amount included in the assessment of effectiveness	412	(6)
Amount excluded from the assessment of effectiveness	52	(30)
Derivatives in Cash Flow Hedging Relationship \| Foreign exchange contracts \| Revenues
Foreign exchange contracts
Amount of gains (losses) reclassified from AOCI to income	26	128
Amount excluded from the assessment of effectiveness recognized in earnings based on an amortization approach	23	9
Derivatives in Cash Flow Hedging Relationship \| Foreign exchange contracts \| Other income (expense), net
Foreign exchange contracts
Amount of gains (losses) reclassified from AOCI to income	0	0
Amount excluded from the assessment of effectiveness recognized in earnings based on an amortization approach	0	0
Derivatives in Net Investment Hedging Relationship: \| Foreign exchange contracts
Derivatives in Net Investment Hedging Relationship:
Amount included in the assessment of effectiveness	80	64
Derivatives in Net Investment Hedging Relationship: \| Foreign exchange contracts \| Revenues
Foreign exchange contracts
Amount excluded from the assessment of effectiveness	0	0
Derivatives in Net Investment Hedging Relationship: \| Foreign exchange contracts \| Other income (expense), net
Foreign exchange contracts
Amount excluded from the assessment of effectiveness	78	54
Derivatives in Fair Value Hedging Relationship \| Foreign exchange contracts \| Revenues
Foreign exchange contracts
Hedged items	0	0
Derivatives designated as hedging instruments	0	0
Amount excluded from the assessment of effectiveness	0	0
Derivatives in Fair Value Hedging Relationship \| Foreign exchange contracts \| Other income (expense), net
Foreign exchange contracts
Hedged items	(17)	22
Derivatives designated as hedging instruments	17	(22)
Amount excluded from the assessment of effectiveness	$ 1	$ 10

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