Loans - Consumer, Excluding Credit Card Loan Portfolio, PCI Accretable Yield Activity (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	$ 928,887	$ 947,651	$ 928,887	$ 947,651	$ 969,415
Consumer, excluding credit card
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	331,809	375,958	331,809	375,958	373,637
Consumer, excluding credit card \| In Process of Active or Suspended Foreclosure
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	546		546		653
Consumer, excluding credit card \| Total PCI
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	197,456		197,456		231,078
Consumer, excluding credit card \| Residential real estate – PCI \| Total PCI
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning balance	7,699	8,722	8,422	11,159
Accretion into interest income	(272)	(303)	(841)	(958)
Changes in interest rates on variable-rate loans	(308)	37	(402)	(231)
Other changes in expected cash flows	255	46	195	(1,468)
Ending balance	$ 7,374	$ 8,502	$ 7,374	$ 8,502
Accretable yield percentage	5.27%	4.95%	5.32%	4.88%
Loans	$ 21,290		$ 21,290		24,034
Consumer, excluding credit card \| Residential real estate – PCI \| Total PCI \| In Process of Active or Suspended Foreclosure
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Loans	$ 776		$ 776		$ 964

Accretable yield percentage.

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- Definition

Changes in the accretable yield due to changes in interest rates on variable rate loans.

+ References

No definition available.

+ Details

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- Definition

Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Other Changes to Nonaccretable Difference

+ References

No definition available.

+ Details

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- Definition

Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118938799&loc=d3e13503-111538

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544

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- Definition

Amount of accretion recognized for the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities, with evidence of deterioration of credit quality.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

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