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Fair Value Measurements (Summary Of Quantitative Information About Level 3 Fair Value Measurements) (Details) - Discounted Cash Flow [Member] - Residential Mortgage [Member] $ in Millions	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 1,026	$ 906
Recurring Fair Value Measurements [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted Average CPR	0.039	0.056
Option-Adjusted Spread	4.60%	4.50%
Recurring Fair Value Measurements [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted Average CPR	0.280	0.215
Option-Adjusted Spread	8.20%	8.20%
Recurring Fair Value Measurements [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted Average CPR	0.082	0.082
Option-Adjusted Spread	4.90%	4.80%

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- Definition

Option-Adjusted Spread

+ References

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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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

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- Definition

Value of input used to measure servicing asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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