Derivative Financial Instruments - Schedule of Differences Between the Gains (Losses) on the Derivative and the Gains (Losses) on the Hedged Item (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Derivative [Line Items]
Gain (loss) on derivative recognized in OCI, cash flow hedge	$ 45	$ 19
Gain (loss) on derivative recognized in OCI, net investment hedge	185	(41)
Other comprehensive income (loss), derivative, before reclassification and tax	230	(22)
Gain (loss) on hedges reclassified to income, cash flow hedge	199	(51)
Other comprehensive income (loss), derivative, gain (loss), reclassification, before tax	199	(51)
Gain (loss) on hedges reclassified to income, net investment hedge	$ 0	0
Floating-rate loans
Derivative [Line Items]
Term of debt instrument	5 years
Interest rate contracts
Derivative [Line Items]
Gain (loss) on derivative recognized in OCI, cash flow hedge	$ (14)	3
Interest rate contracts \| Net interest income
Derivative [Line Items]
Gain (loss) on hedges reclassified to income, cash flow hedge	(55)	(51)
Foreign exchange contracts
Derivative [Line Items]
Gain (loss) on derivative recognized in OCI, cash flow hedge	59	16
Gain (loss) on derivative recognized in OCI, net investment hedge	185	(41)
Foreign exchange contracts \| Net interest income
Derivative [Line Items]
Gain (loss) on hedges reclassified to income, cash flow hedge	254	0
Foreign exchange contracts \| Gains (losses) related to investment securities, net
Derivative [Line Items]
Gain (loss) on hedges reclassified to income, net investment hedge	$ 0	$ 0

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-Section 50
-Paragraph 4CCC
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Amount, before tax, of reclassification from accumulated other comprehensive income (AOCI) for gain (loss) from derivative designated and qualifying as net investment hedge.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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