Derivative Financial Instruments - Impact on Derivatives and Hedged Items on Consolidated Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain (loss) on derivative recognized in consolidated statement of income	$ (19)	$ 88	$ 47	$ 107
Amount of gain (loss) on hedged item recognized in consolidated statement of income	19	(88)	(48)	(109)
Net unrealized gains (losses) on available-for-sale securities designated in fair value hedges, net of related taxes	36	256	70	526
Available-for-sale securities \| Net interest income \| Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain (loss) on derivative recognized in consolidated statement of income	57	349	99	707
Amount of gain (loss) on hedged item recognized in consolidated statement of income	(57)	(349)	(100)	(709)
Long-term debt \| Net interest income \| Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain (loss) on derivative recognized in consolidated statement of income	(76)	(261)	(52)	(600)
Amount of gain (loss) on hedged item recognized in consolidated statement of income	$ 76	$ 261	$ 52	$ 600

Other Comprehensive Income (Loss), Securities, Available-For-Sale, Designated In Fair Value Hedges, Unrealized Holding Gain (Loss) Arising During Period, After Tax

No definition available.

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- Definition

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 815
-SubTopic 25
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480238/815-25-50-1

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- Definition

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

+ References

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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.

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