Loan Servicing - Residential MSR Sensitivity (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2026	Dec. 31, 2025
Residential MSRs
Servicing Assets at Fair Value [Line Items]
Composition of loans serviced for others	100.00%	100.00%
Residential MSRs \| Minimum
Servicing Assets at Fair Value [Line Items]
Prepayment speed	5.80%	6.10%
OAS	1.30%	1.40%
Residential MSRs \| Maximum
Servicing Assets at Fair Value [Line Items]
Prepayment speed	8.50%	13.90%
OAS	12.00%	12.20%
Residential MSRs \| Weighted Average
Servicing Assets at Fair Value [Line Items]
Prepayment speed	6.40%	7.20%
Effect on fair value of a 10% increase	$ (124)	$ (107)
Effect on fair value of a 20% increase	$ (240)	$ (208)
OAS	3.80%	4.40%
Effect on fair value of a 10% increase	$ (81)	$ (75)
Effect on fair value of a 20% increase	$ (159)	$ (146)
Weighted average life	7 years 10 months 24 days	7 years 7 months 6 days
Fixed-rate residential mortgage loans
Servicing Assets at Fair Value [Line Items]
Composition of loans serviced for others	99.50%	99.70%
Adjustable-rate residential mortgage loans
Servicing Assets at Fair Value [Line Items]
Composition of loans serviced for others	0.50%	0.30%

Option adjusted spread assumption used in valuing MSRs

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- Definition

Composition Of Mortgage Loans Serviced For Others

+ References

No definition available.

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- Definition

Effect on fair value of a 10% increase in weighted average OAS

+ References

No definition available.

+ Details

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- Definition

Effect on fair value of a 20% increase in weighted average OAS

+ References

No definition available.

+ Details

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- Definition

Weighted-average life of securitized asset regardless of when transfer occurred, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481326/860-20-50-4

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- Definition

Estimated rate of prepayment of principal on financial assets regardless of when the transfer occurred.

+ References

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- Definition

The hypothetical financial impact of a 10 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 860
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481326/860-20-50-4

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- Definition

The hypothetical financial impact of a 20 percent adverse change of prepayment speed on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ 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/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(4)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481229/860-50-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481229/860-50-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481229/860-50-50-3

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481229/860-50-50-3

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481229/860-50-50-4

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