Loans and Allowance for Credit Losses - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019 USD ($) MortgageLoan	Jun. 30, 2019 USD ($) SecurityLoan MortgageLoan	Dec. 31, 2018 USD ($)
Loans and Allowance for Credit Losses [Line Items]
Loans pledged at the Federal Home Loan Bank	$ 92,200	$ 92,200	$ 88,700
Loans pledged at the Federal Reserve Bank	74,200	74,200	70,100
Unearned interest and deferred fees and costs on originated loans	815	815	872
Foreclosed residential real estate property included in other real estate owned	84	84	106
Foreclosed residential real estate related to mortgage loans whose payments are insured by the Federal Housing Administration or guaranteed by the United States Department of Veterans Affairs	201	201	235
Residential mortgage loans secured by residential real estate in process of foreclosure	$ 1,500	$ 1,500	1,500
Number of residential mortgage loans, home equity and second mortgage loans, and GNMA loans where trial period was unsuccessful and no longer eligible for a permanent modification \| MortgageLoan	156	415
Outstanding balance of residential mortgage loans, home equity and second mortgage loans, and GNMA loans where trial period was unsuccessful and no longer eligible for a permanent modification	$ 23	$ 56
Government National Mortgage Association [Member]
Loans and Allowance for Credit Losses [Line Items]
Residential mortgage loans secured by residential real estate in process of foreclosure	$ 1,200	$ 1,200	$ 1,200
Home Equity and Second Mortgages [Member]
Loans and Allowance for Credit Losses [Line Items]
Number of loans in trial period \| SecurityLoan		19
Outstanding balance of loans in trial period		$ 1
Estimated post-modification balance of loans in trial period		$ 1
Residential Mortgages [Member]
Loans and Allowance for Credit Losses [Line Items]
Number of loans in trial period \| SecurityLoan		45
Outstanding balance of loans in trial period		$ 6
Estimated post-modification balance of loans in trial period		$ 6
Government National Mortgage Association [Member]
Loans and Allowance for Credit Losses [Line Items]
Number of loans in trial period \| SecurityLoan		1,125
Outstanding balance of loans in trial period		$ 155
Estimated post-modification balance of loans in trial period		$ 153

Amount of loan receivable in which the terms of the loan agreement have been modified on a trial basis.

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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

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- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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- Definition

The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of FHLB debt obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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Foreclosed residential real estate related to mortgage loans whose payments are insured by the Federal Housing Administration or guaranteed by the United States Department of Veterans Affairs.

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Loan restructuring trial modifications estimated post-modification balance.

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Loans and allowance for credit losses.

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Number of loans in trial period.

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Number of residential mortgage loans, home equity and second mortgage loans, and GNMA loans where trial period was unsuccessful and no longer eligible for a permanent modification.

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Outstanding balance of residential mortgage loans, home equity and second mortgage loans, and GNMA loans where trial period was unsuccessful and no longer eligible for a permanent modification.

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Pledged financial instruments not separately reported loans receivable pledged for federal reserve bank debt.

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Residential mortgage loans secured by residential real estate in process of foreclosure

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