Derivatives (Derivative Financial Instruments - Additional Information) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Derivative
Valuation adjustments related to the credit risk associated with counterparties of customer accommodation derivative contracts	$ 17	$ 3
Deferred gains, net of tax, on cash flow hedges were recorded in accumulated other comprehensive income	422	160
Notional amount of the risk participations agreements	3,943	4,002
Amount of variation margin payment applied to derivative asset contracts	623	249
Amount of variation margin payment applied to derivative liability contracts	$ 488	23
Interest Rate Contract [Member] \| Credit Risk [Member]
Derivative
Credit Risk Derivatives Average Life	3 years 7 months 6 days
Fair value of risk participation agreements	$ 8	8
Interest Rate Contract [Member] \| Cash Flow Hedging
Derivative
Maximum Length of Time Hedged in Interest Rate Cash Flow Hedge	60 months
Net deferred gains or losses, net of tax, recorded in AOCI are expected to be reclassified into earnings	$ 101
Total collateral
Derivative
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	894	481
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 347	$ 551

Variation margin payments derivative assets.

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- Definition

Variation margin payments derivative liabilities.

+ References

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- Definition

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Amount of credit risk valuation adjustment to derivative assets to properly reflect the credit quality of the counterparties.

+ References

No definition available.

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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.

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Fair value, after effects of master netting arrangements, 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 offset against the right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

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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.

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- Definition

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Fair value of all derivative liabilities not designated as a hedging instrument.

+ References

No definition available.

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