Variable Interest Entities - Loans Sold to Third-Party Sponsored Securitization Entities (Details) - Nonconsolidated entities - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summary of loan sale activities [Abstract]
Carrying value of loans sold	$ 11,968	$ 15,402	$ 28,804	$ 44,282
Proceeds received from loan sales as cash	1	104	1	117
Proceeds from loans sales as securities	11,713	15,093	28,291	43,682
Total proceeds received from loan sales	11,714	15,197	28,292	43,799
Gains on loan sales	$ 9	$ 41	$ 32	$ 114

Proceeds received from the sale of originated and purchased mortgage loans.

No definition available.

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- Definition

Securities proceeds received from the sale of originated and purchased mortgage loans.

+ References

No definition available.

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- Definition

Summary Of Loan Sale Activities.

+ References

No definition available.

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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

Mortgage loan related to property sales in noncash investing and financing activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

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- Definition

The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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