Fair Value of Assets and Liabilities - Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ (14)	$ (23)	$ (32)
Acquired		0
Total net gains (losses) included in net income	(19)	(1)	(4)
Purchases	0	0	0
Sales	0	0	0
Settlements	10	10	13
Net transfers into (out of) Level 3	0	0	0
Ending balance	(23)	(14)	(23)
Net unrealized gains (losses) included in net income	(19)	(1)	(4)
Trading securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	1	2
Acquired		0
Total net gains (losses) included in net income		(1)	0
Purchases		0	0
Sales		0	0
Settlements		0	(1)
Net transfers into (out of) Level 3		0	0
Ending balance		0	1
Net unrealized gains (losses) included in net income		0	0
Interest-only strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	32	19	10
Acquired		0
Total net gains (losses) included in net income	3	(6)	(5)
Purchases	0	6	0
Sales	(68)	(11)	(47)
Settlements	0	0	0
Net transfers into (out of) Level 3	71	24	61
Ending balance	38	32	19
Net unrealized gains (losses) included in net income	(2)	(4)	(2)
Loans held for sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	12	14	16
Acquired		0
Total net gains (losses) included in net income	1	1	2
Purchases	10	0	0
Sales	(18)	0	0
Settlements	(3)	(3)	(4)
Net transfers into (out of) Level 3	26	0	0
Ending balance	28	12	14
Net unrealized gains (losses) included in net income	1	1	2
Loans held for investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	16	0
Acquired		14
Total net gains (losses) included in net income	0	0
Purchases	0	0
Sales	0	(4)
Settlements	(2)	(3)
Net transfers into (out of) Level 3	(14)	9
Ending balance	0	16	$ 0
Net unrealized gains (losses) included in net income	$ 0	$ 0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Acquisition

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Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Acquisition

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No definition available.

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

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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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Fair value of financial instrument classified as 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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