Loans - Consumer, Excluding Credit Card Loan Portfolio, Loan Modifications, Nature and Extent of Modifications (Details) - Consumer, excluding credit card - Residential real estate $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Financing Receivable, Impaired [Line Items]
New TDRs \| $	$ 819	$ 490	$ 736
Percentage, sum of items by type, may exceed	100.00%
Trial Modification
Financing Receivable, Impaired [Line Items]
Number of loans modified	5,522	5,872	7,175
Permanent Modification
Financing Receivable, Impaired [Line Items]
Number of loans modified	6,850	4,918	7,853
Interest rate reduction
Financing Receivable, Impaired [Line Items]
Concession granted	50.00%	77.00%	54.00%
Term or payment extension
Financing Receivable, Impaired [Line Items]
Concession granted	49.00%	71.00%	62.00%
Principal and/or interest deferred
Financing Receivable, Impaired [Line Items]
Concession granted	14.00%	13.00%	29.00%
Principal forgiveness
Financing Receivable, Impaired [Line Items]
Concession granted	2.00%	5.00%	7.00%
Other
Financing Receivable, Impaired [Line Items]
Concession granted	66.00%	63.00%	51.00%

Financing Receivable, Modifications, Percentage of Modifications

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- Definition

In a group of items by type, the percentage that the sum of the items may exceed due to the inclusion of some items in more than one category. For example, in loan modifications, some loans may have more than one type of concession granted on the loan, so a sum of all types of loan modifications granted would exceed 100%.

+ References

No definition available.

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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.

+ References

No definition available.

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

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- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

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