v3.26.3
Fair Value Measurements - Changes in Unrealized Gains (Losses) Included in Net Income for Financial Instruments Classified as Level 3 Still Held at Year End (Details) - Significant
Unobservable
Inputs
(Level 3) - Fair Value, Recurring [Member] - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets $ (3) $ 7 $ (43) $ (7)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Net realized losses Net realized losses Net realized losses Net realized losses
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI $ (37) $ 4 $ (74) $ 66
Equity Securities [Member]        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets 0 0 (2) 0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI 0 0 0 0
Securities available-for-sale and other        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets (3) 0 (4) 3
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI (37) 4 (74) 66
ABS | Securities available-for-sale and other        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets 0 0 (1) 0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI (7) 0 (10) 1
CMBS | Securities available-for-sale and other        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets 0 0 0 0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI (2) 2 (2) 5
Corporate | Securities available-for-sale and other        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets (3) 0 (3) 3
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI (28) 2 (61) 60
Collateralized Loan Obligations [Member] | Securities available-for-sale and other        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets 0 0 0 0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI 0 0 (1) 0
Collateralized Loan Obligations [Member] | Fair Value Option, Other Eligible Items        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets 0 7 (37) (10)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI $ 0 $ 0 $ 0 $ 0