Fair Value of Assets and Liabilities - Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Net derivative liabilities
Beginning balance	$ (23)	$ (14)
Total net gains (losses) included in net income		(9)
Purchases	0
Sales	0	0
Settlements	5	2
Net transfers into (out of) Level 3	0	0
Ending balance	(18)	(21)
Net unrealized gains (losses) included in net income	0	(9)
Interest- only strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	38	32
Total net gains (losses) included in net income		5
Purchases	0
Sales	(37)	(27)
Settlements	0	0
Net transfers into (out of) Level 3	11	12
Ending balance	12	22
Net unrealized gains (losses) included in net income	(1)	2
Loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	28	12
Total net gains (losses) included in net income		1
Purchases	1
Sales	0	0
Settlements	(1)	(1)
Net transfers into (out of) Level 3	4	0
Ending balance	32	12
Net unrealized gains (losses) included in net income	$ 0	1
Loans held for investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		16
Total net gains (losses) included in net income		0
Sales		0
Settlements		(2)
Net transfers into (out of) Level 3		3
Ending balance		17
Net unrealized gains (losses) included in net income		$ 0

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

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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 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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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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No definition available.

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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 unrealized gain (loss) recognized in income for derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), 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 derivative asset (liability) after deduction of derivative liability (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 sales of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (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 settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative 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 transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into (out of) level 3 of the fair value hierarchy.

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