Derivatives - Derivatives Associated with Interest Rate Risk Management Activities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Customer interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional	$ 4,158	$ 4,067
Assets	37	22
Liabilities	132	197
Customer interest rate contracts \| Customer Interest Rate Contracts Hedging \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Notional	8,385	8,375
Assets	48	21
Liabilities	257	392
Offsetting upstream interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional	4,329	4,273
Assets	89	135
Liabilities	38	23
Offsetting upstream interest rate contracts \| Customer Interest Rate Contracts Hedging \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Notional	8,385	8,375
Assets	255	389
Liabilities	$ 48	$ 22

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4E

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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
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

No definition available.

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- Definition

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

+ References

No definition available.

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