Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

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The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Fair value of securities received as collateral against derivative assets.

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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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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Fair value of securities pledged as collateral against derivative liabilities.

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Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 15,750,000,000		$ 15,750,000,000		$ 9,400,000,000
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	18,000,000		18,000,000		16,000,000
Aggregate fair value of derivative financial instruments in a liability position	3,000,000		3,000,000		13,000,000
Net liability positions with counterparties	3,000,000		3,000,000		13,000,000
Aggregate fair value of derivative financial instruments in asset position	49,000,000		49,000,000		13,000,000
Net fair value of derivative financial instruments in a net asset position	49,000,000		49,000,000		13,000,000
Collateral relating to net asset positions	46,000,000		46,000,000		12,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	3,000,000		3,000,000		12,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	48,000,000		48,000,000		52,000,000
Reduction in the fair value of derivative asset due to contractual settlements			(302,000,000)
Reduction in the fair value of derivative liability due to contractual settlements			(149,000,000)
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	(8,000,000)	$ 7,000,000	(12,000,000)	$ 18,000,000
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	40,300,000,000		40,300,000,000		29,900,000,000
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	869,000,000		869,000,000		$ 530,000,000
Credit Risk Derivative [Member]
Derivative [Line Items]
Fair value of additional collateral to be posted for derivative financial instruments	$ 0		$ 0