Mortgage Servicing Rights and Related Liabilities - Narrative (Details) - USD ($)	5 Months Ended	7 Months Ended	12 Months Ended
Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Servicing Assets at Fair Value [Line Items]
Mortgage servicing liabilities	$ 71,000,000		$ 61,000,000	$ 71,000,000
MSL accretion	(15,000,000)		(47,000,000)
Mortgage servicing rights at fair value	3,665,000,000		3,496,000,000	3,665,000,000
Forward MSRs Sold
Servicing Assets at Fair Value [Line Items]
Unpaid principal balance sold	10,746,000,000	$ 1,203,000,000	35,152,000,000
Forward MSRs Sold, Subservicing Retained
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	0	1,000,000	20,560,000,000	0
Reverse mortgage interests
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	28,415,000,000		22,725,000,000	28,415,000,000
Mortgage Servicing Right Liability
Servicing Assets at Fair Value [Line Items]
MSL accretion	(15,000,000)	(11,000,000)	(47,000,000)
Impairment		56,000,000
Mortgage Servicing Rights
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	295,481,000,000		296,782,000,000	295,481,000,000
Mortgage servicing liabilities	71,000,000		61,000,000	71,000,000
Increase (decrease) servicing liability, amortized cost			37,000,000
Impairment			0	0
Reverse MSRs - amortized cost	11,000,000		6,000,000	11,000,000
Fair value of servicing liability, amortized cost	53,000,000		28,000,000	53,000,000
Mortgage servicing rights at fair value	3,665,000,000		3,496,000,000	3,665,000,000
Reverse Mortgage Servicing Rights
Servicing Assets at Fair Value [Line Items]
Impairment		$ 4,000,000
Amortization	(4,000,000)		(1,000,000)
Other changes, servicing asset, amortized cost			4,000,000
Mortgage servicing rights at fair value	$ 11,000,000		$ 6,000,000	$ 11,000,000

Fair Value of Servicing Liability, Amortized Cost

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- Definition

Principal Amount Outstanding On Loans Managed And Securitized, Sold

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No definition available.

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Servicing Liability at Amortized Cost, Accretion

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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
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- Definition

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

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of amortization of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of other increase (decrease) to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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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
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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.

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Amortized amount of contract to service financial assets under which estimated future revenues from contractually specified servicing fees, late charges, and other ancillary revenue are not expected to adequately compensate the servicer for performing the servicing.

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Amount of increase (decrease) to contract to service financial assets under which estimated future revenue from contractually specified servicing fees, late charges, and other ancillary revenues are not expected to adequately compensate the servicer for performing the servicing.

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