Derivatives - Derivatives Associated with Cash Flow Hedges and Mortgage Banking Hedges (Details) - Hedging Instruments And Hedged Items - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Interest Rate Contract \| Cash Flow Hedge
Derivative Instruments, Gain (Loss) [Line Items]
Variability in cash flows related to debt instruments (primarily loans)	$ 5,000	$ 5,200
Interest Rate Swap \| Cash Flow Hedge
Derivative Instruments, Gain (Loss) [Line Items]
Notional	5,000	5,200
Assets	0	0
Liabilities	9	32
Option contracts written \| Mortgage Banking Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Notional	77	55
Assets	1	1
Liabilities	0	0
Forward contracts written \| Mortgage Banking Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Notional	123	93
Assets	0	0
Liabilities	$ 0	$ 1

Held-to-maturity trust preferred loans.

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- Definition

Fair value of all asset derivatives designated as cash flow hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

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- Definition

Fair value of all liability derivatives designated as cash flow hedging instruments.

+ References

+ Details

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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

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

Aggregate fair value of all derivative assets designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

+ References

No definition available.

+ Details

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- Definition

Aggregate fair value of all derivative liabilities designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

+ 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
-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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