Mortgage Servicing Rights and Related Liabilities - UPB and Related Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Servicing Assets at Fair Value [Line Items]
Mortgage servicing rights at fair value	$ 3,496	$ 3,665
Mortgage Servicing Rights
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	296,782	295,481
Mortgage servicing rights at fair value	3,496	3,665
Mortgage Servicing Rights \| Credit sensitive
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	147,895	135,752
Mortgage servicing rights at fair value	1,613	1,495
Mortgage Servicing Rights \| Interest sensitive
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	148,887	159,729
Mortgage servicing rights at fair value	$ 1,883	$ 2,170

This is the sum of principal amount outstanding for both securitized and unsecuritized loans of all types.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118948506&loc=d3e107314-111719

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746

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+ References

No definition available.

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