Loan Servicing - Residential Mortgage Banking Activities (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Servicing fees recognized from mortgage loans serviced for others	$ 1,222	$ 1,220	$ 2,402	$ 2,391
Residential
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
UPB of residential mortgage and home equity loan servicing portfolio	118,753		118,753		$ 118,424
UPB of residential mortgage loans serviced for others, primarily agency conforming fixed rate	88,492		88,492		89,124
Mortgage loans sold with recourse	452		452		490
Maximum recourse exposure from mortgage loans sold with recourse liability	237		237		251
Indemnification, recourse and repurchase reserves	$ 34		34		$ 37
UPB of residential mortgage loans sold from LHFS			5,536	6,309
Pre-tax gains recognized on mortgage loans sold and held for sale			$ 74	$ 65
Approximate weighted average servicing fee on the outstanding balance of residential mortgage loans serviced for others	0.28%	0.28%	0.28%	0.28%
Weighted average interest rate on mortgage loans serviced for others	4.01%	4.00%	4.01%	4.00%
Bank Servicing \| Residential
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Servicing fees recognized from mortgage loans serviced for others			$ 128	$ 133

Represents the carrying amount of residential mortgage loans sold with recourse.

No definition available.

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- Definition

Represents the weighted average servicing fee earned from servicing residential mortgage loans. The amount is presented as the percentage of fee income divided by the outstanding balances of the residential mortgage loans being serviced.

+ References

No definition available.

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- Definition

Represents the unpaid principal balance of total residential mortgage servicing portfolio. This includes the unpaid principal balances held for investment included on the balance sheet as well as the portion serviced for others representing the balances sold to third-party investors.

+ References

No definition available.

+ Details

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- Definition

Represents the unpaid principal balance of residential mortgage loans serviced for others that were previously sold to third-party investors.

+ References

No definition available.

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- Definition

Represents the weighted average interest rate on the portfolio of residential mortgage loans serviced for others.

+ References

No definition available.

+ Details

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- Definition

The amount of any significant sales of financing receivables during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=115931803&loc=d3e12069-110248

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=115931803&loc=d3e12069-110248

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- Definition

The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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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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