Fair Value Measurements - Level 3 Reconciliation (Details) - Recurring Fair Value Measurements - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Excess spread financing
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of period	$ 934	$ 1,311
Changes in fair value included in earnings	14	(101)
Other changes	0	0
Purchases	0	0
Issuances	0	24
Sales	0
Settlements and repayments	(81)	(110)
Balance - end of period	867	1,124
Mortgage servicing rights financing
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of period	33	37
Changes in fair value included in earnings	(12)	12
Other changes	0	0
Purchases	0	0
Issuances	0	0
Sales	0
Settlements and repayments	0	0
Balance - end of period	21	49
Forward mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of period	2,703	3,496
Changes in fair value included in earnings	(190)	(1,055)
Other changes	34	43
Purchases	218	24
Issuances	554	249
Sales	(12)
Settlements and repayments	0	0
Balance - end of period	3,307	2,757
IRLCs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of period	414	135
Changes in fair value included in earnings	(210)	235
Other changes	0	0
Purchases	0	0
Issuances	0	0
Sales	0
Settlements and repayments	0	0
Balance - end of period	204	$ 370
LPCs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of period	38
Changes in fair value included in earnings	(28)
Other changes	0
Purchases	0
Issuances	0
Sales	0
Settlements and repayments	0
Balance - end of period	$ 10

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Other Fair Value Changes

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- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Other Fair Value Changes

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No definition available.

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

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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