Derivative Financial Instruments - Hedging Programs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Instruments in net investment hedges
Derivative Financial Instruments
Notional amount	$ 8,200	$ 7,200
Average remaining maturity	2 months 12 days	3 months 18 days
Interest rate swaps \| Derivative instruments in fair value hedges
Derivative Financial Instruments
Notional amount	$ 400	$ 3,000
Amount of terminated derivative	$ 1,250
Average remaining maturity	2 years	1 year 2 months 12 days
Interest rate swaps \| Derivative instruments in cash flow hedges
Derivative Financial Instruments
Notional amount	$ 0	$ 0
Foreign exchange contracts \| Not designated as hedging instruments - economic hedges
Derivative Financial Instruments
Notional amount	$ 6,100	6,800
Foreign exchange contracts \| Not designated as hedging instruments - economic hedges \| Maximum
Derivative Financial Instruments
Term of contract	1 year
Foreign exchange contracts \| Instruments in net investment hedges
Derivative Financial Instruments
Notional amount	$ 15,700	16,400
Foreign exchange forward contracts \| Derivative instruments in cash flow hedges
Derivative Financial Instruments
Maximum length of time hedged	3 years
Notional amount	$ 7,700	$ 8,000
Average remaining maturity	8 months 12 days	8 months 12 days
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges	$ 115	$ (192)
Gains (losses) expected to be reclassified to net income within the next 12 months	$ 30
Cross-currency swaps \| Derivative instruments in cash flow hedges
Derivative Financial Instruments
Maximum length of time hedged	7 years
Notional amount	$ 1,500	1,500
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges	(199)	$ (236)
Gains (losses) expected to be reclassified to net income within the next 12 months	$ (24)
Forward-starting interest rate swaps \| Derivative instruments in cash flow hedges
Derivative Financial Instruments
Number of derivative instruments outstanding	0	0
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges	$ (170)	$ (174)
Gains (losses) expected to be reclassified to net income within the next 12 months	(18)
Equity contracts hedging employee compensation obligations \| Not designated as hedging instruments - economic hedges
Derivative Financial Instruments
Notional amount	$ 1,300	$ 1,300

Amount of terminated derivative instrument.

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- Definition

Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, attributable to parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners).

+ References

No definition available.

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- Definition

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994

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- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

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-Publisher FASB
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-Topic 815
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-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 815
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-Section 50
-Paragraph 1
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