Derivative Instruments and Hedging Activities - Schedule of Estimated Fair Value of Derivative Instruments included in the Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Designated as Hedging Instrument
Derivative [Line Items]
Estimated fair value of derivative assets	$ 139	$ 130
Estimated fair value of derivative liabilities	7	1
Not Designated as Hedging Instruments
Derivative [Line Items]
Estimated fair value of derivative assets	63	41
Estimated fair value of derivative liabilities	139	40
Cash Flow Hedges
Derivative [Line Items]
Estimated fair value of derivative assets	92	83
Estimated fair value of derivative liabilities	0	0
Fair Value Hedges
Derivative [Line Items]
Estimated fair value of derivative assets	48	47
Estimated fair value of derivative liabilities	7	1
Interest rate contracts \| Not Designated as Hedging Instruments
Derivative [Line Items]
Notional Amount	21,991	6,425
Estimated fair value of derivative assets	59	40
Estimated fair value of derivative liabilities	139	40
Interest rate contracts \| Cash Flow Hedges
Derivative [Line Items]
Notional Amount	12,250	9,750
Estimated fair value of derivative assets	92	83
Estimated fair value of derivative liabilities	0	0
Interest rate contracts \| Fair Value Hedges
Derivative [Line Items]
Notional Amount	6,562	4,340
Estimated fair value of derivative assets	48	47
Estimated fair value of derivative liabilities	7	1
Mortgage derivatives - forward commitments to sell fixed-rate mortgage loans \| Not Designated as Hedging Instruments \| Mortgage derivatives - interest rate lock commitments
Derivative [Line Items]
Notional Amount	159	64
Estimated fair value of derivative assets	2	1
Estimated fair value of derivative liabilities	0	0
Mortgage derivatives - forward commitments to sell fixed-rate mortgage loans \| Not Designated as Hedging Instruments \| Mortgage derivatives - forward commitments to sell fixed-rate mortgage loans
Derivative [Line Items]
Notional Amount	150	53
Estimated fair value of derivative assets	1	0
Estimated fair value of derivative liabilities	0	0
Foreign exchange contracts \| Not Designated as Hedging Instruments
Derivative [Line Items]
Notional Amount	171	0
Estimated fair value of derivative assets	1	0
Estimated fair value of derivative liabilities	$ 0	$ 0

Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-7A

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

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- Definition

Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ 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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 181
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480401/815-10-55-181

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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