Fair Value Of Financial Instruments (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Percentage of level 3 assets at fair value in total assets measured at fair value value	4.00%		20.00%
Percentage of level 3 liabilities at fair value in total liabilities measured at fair value	69.00%		68.00%
Cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option	$ (39)		$ (115)
Loan Repurchase Commitments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Payments for Litigation Settlements	600
Instrument-specific credit risk of liabilities measured at fair value, net [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option	36		$ 51
Loss on instrument-specific credit risk recognized in earnings	$ 20	$ 2

Approximate percentage of level 3 assets at fair value in total assets measured at fair value.

No definition available.

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- Definition

Approximate percentage of level 3 liabilities at fair value in total liabilities measured at fair value.

+ References

No definition available.

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

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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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Amount of damages paid to the plaintiff in the legal matter.

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Amount, after tax, of reclassification adjustment from accumulated other comprehensive income (loss) for unrealized gain (loss) from increase (decrease) in instrument-specific credit risk, realized upon derecognition of financial liability measured under fair value option.

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