Loans - Consumer, Excluding Credit Card Loan Portfolio, Impaired Loans (Details) - Consumer, excluding credit card $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) payment	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Impaired loans
Loans modified subsequent to repurchase from Ginnie Mae	$ 4,000		$ 4,000		$ 3,800
TDRs less than 90 days past due	2,000		2,000		2,200
Total residential real estate – excluding PCI
Impaired loans
With an allowance	4,735		4,735		5,643
Without an allowance	2,043		2,043		2,095
Total impaired loans	6,778		6,778		7,738
Allowance for loan losses related to impaired loans	139		139		173
Unpaid principal balance of impaired loans	9,976		9,976		11,442
Impaired loans on nonaccrual status	2,529		2,529		2,775
Average impaired loans	6,937	$ 7,893	7,334	$ 8,074
Interest income on impaired loans	94	103	295	312
Interest income on impaired loans on a cash basis	40	39	$ 121	117
Number of payments under modified terms to recognize interest on cash basis \| payment			6
Residential mortgage
Impaired loans
With an allowance	3,558		$ 3,558		4,407
Without an allowance	1,164		1,164		1,213
Total impaired loans	4,722		4,722		5,620
Allowance for loan losses related to impaired loans	97		97		62
Unpaid principal balance of impaired loans	6,439		6,439		7,741
Impaired loans on nonaccrual status	1,536		1,536		1,743
Average impaired loans	4,872	5,743	5,242	5,861
Interest income on impaired loans	61	71	197	217
Interest income on impaired loans on a cash basis	19	19	$ 58	57
Residential mortgage \| Permanent Modification
Impaired loans
Rate of default for modified loans, estimated weighted average			13.00%
Home equity
Impaired loans
With an allowance	1,177		$ 1,177		1,236
Without an allowance	879		879		882
Total impaired loans	2,056		2,056		2,118
Allowance for loan losses related to impaired loans	42		42		111
Unpaid principal balance of impaired loans	3,537		3,537		3,701
Impaired loans on nonaccrual status	993		993		$ 1,032
Average impaired loans	2,065	2,150	2,092	2,213
Interest income on impaired loans	33	32	98	95
Interest income on impaired loans on a cash basis	$ 21	$ 20	$ 63	$ 60
Home equity \| Permanent Modification
Impaired loans
Rate of default for modified loans, estimated weighted average			9.00%

Impaired Financing Receivable, Recorded Investment, Nonaccrual Status

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- Definition

Represents the carrying amount of loans with terms that have been modified in trouble debt restructurings that have not yet made six payments under the modified terms.

+ References

No definition available.

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- Definition

Loans that are repurchased from US government agencies, such as the Government National Mortgage Association (GNMA or Ginnie Mae), and modified subsequent to repurchase. These loans are excluded from loans accounted for as troubled debt restructurings.

+ References

No definition available.

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- Definition

For loans modified in TDRs, the number of borrower payments under the modified terms to generally be recognized as interest income on a cash basis.

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This item represents the estimated weighted average default rate for modified loans.

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Section 50
-Paragraph 14A
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Amount of allowance for credit losses related to recorded investment.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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