Fair Value Measurements - Reconciliation of Level 3 (Details) - Fair Value, Recurring - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Excess Spread Financing
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of year	$ 934	$ 1,311
Changes in fair value included in earnings	(10)	(194)
Purchases	0	0
Equity consideration received	0
Issuances	0	24
Sales	0	0
Settlements and repayments	(156)	(207)
Other changes	0	0
Balance - end of year	768	934
Mortgage Servicing Rights Financing
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of year	33	37
Changes in fair value included in earnings	(23)	(4)
Purchases	0	0
Equity consideration received	0
Issuances	0	0
Sales	0	0
Settlements and repayments	0	0
Other changes	0	0
Balance - end of year	10	33
Forward Mortgage Servicing Rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of year	2,703	3,496
Changes in fair value included in earnings	(506)	(1,667)
Purchases	948	124
Equity consideration received	0
Issuances	1,077	687
Sales	(55)	(9)
Settlements and repayments	0	0
Other changes	56	(72)
Balance - end of year	4,223	2,703
IRLCs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of year	414	135
Changes in fair value included in earnings	(280)	279
Purchases	0	0
Equity consideration received	0
Issuances	0	0
Sales	0	0
Settlements and repayments	0	0
Other changes	0	0
Balance - end of year	134	414
LPCs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of year	38	12
Changes in fair value included in earnings	(35)	26
Purchases	0	0
Equity consideration received	0
Issuances	0	0
Sales	0	0
Settlements and repayments	0	0
Other changes	0	0
Balance - end of year	3	38
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance - beginning of year	0
Changes in fair value included in earnings	(1)
Purchases	0
Equity consideration received	55
Issuances	0
Sales	0
Settlements and repayments	0
Other changes	0
Balance - end of year	$ 54	$ 0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Equity Consideration Received

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

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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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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 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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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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