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Fair Value of Assets and Liabilities - Schedule of Changes In Level 3 Assets And Liabilities Measured At Fair Value (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |  |
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other expense | Other expense | Other expense
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other expense | Other expense |
Level 3 |  |  |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |  |
Beginning balance | $ (27) | $ (23) | $ (14)
Total net gains (losses) included in net income | (15) | (23) | (19)
Purchases | 0 | 0 | 0
Sales | 0 | 0 | 0
Settlements | 19 | 19 | 10
Repayments |  | 0 |
Net transfers into (out of) Level 3 | 0 | 0 | 0
Ending balance | (23) | (27) | (23)
Net unrealized gains (losses) included in net income | (15) | (23) | (19)
Interest-only strips | Level 3 |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Beginning balance | 25 | 38 | 32
Total net gains (losses) included in net income | (12) | (7) | 3
Purchases | 0 | 0 | 0
Sales | (54) | (76) | (68)
Settlements | 0 | 0 | 0
Repayments |  | 0 |
Net transfers into (out of) Level 3 | 54 | 70 | 71
Ending balance | 13 | 25 | 38
Net unrealized gains (losses) included in net income | (1) | (2) | (2)
Loans held for sale | Level 3 |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Beginning balance | 22 | 28 | 12
Total net gains (losses) included in net income | 4 | 0 | 1
Purchases | 3 | 2 | 10
Sales | (3) | (12) | (18)
Settlements | (2) | (2) | (3)
Repayments |  | (1) |
Net transfers into (out of) Level 3 | 2 | 7 | 26
Ending balance | 26 | 22 | 28
Net unrealized gains (losses) included in net income | $ 4 | 0 | 1
Loans held for investment | Level 3 |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Beginning balance |  | $ 0 | 16
Total net gains (losses) included in net income |  |  | 0
Purchases |  |  | 0
Sales |  |  | 0
Settlements |  |  | (2)
Net transfers into (out of) Level 3 |  |  | (14)
Ending balance |  |  | 0
Net unrealized gains (losses) included in net income |  |  | $ 0

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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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