Mortgage Servicing Rights and Related Liabilities - Narrative (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Forward MSRs Sold
Servicing Assets at Fair Value [Line Items]
Unpaid principal balance sold	$ 1,070,000,000	$ 35,152,000,000
Forward MSRs Sold, Subservicing Retained
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	960,000,000	20,560,000,000
Reverse mortgage interests, net
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	18,091,000,000	22,725,000,000
Mortgage Servicing Right Liability
Servicing Assets at Fair Value [Line Items]
Excess spread financing - fair value	934,000,000	1,311,000,000
Mortgage servicing rights financing - fair value	33,000,000	37,000,000
Mortgage Servicing Rights
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	271,189,000,000	296,782,000,000
Impairment	$ 0	$ 0

Excess Spread Financing, Fair Value Disclosure

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- Definition

Mortgage Servicing Rights Liability Resulting from Sale or Securitization of Servicer Advances, Rights not Accounted for as a Sale

+ References

No definition available.

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- Definition

Principal Amount Outstanding On Loans Managed And Securitized, Sold

+ References

No definition available.

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- Definition

The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275

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- Definition

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

+ References

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=121570589&loc=d3e107314-111719

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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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