v3.26.1
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 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Changes in Unrealized Gain/(Loss) Included in Net Income, Assets $ (4) $ (13) $ (39) $ (14)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Net realized gains (losses) Net realized gains (losses) Net realized gains (losses) Net realized gains (losses)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI $ 2 $ 46 $ (37) $ 62
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 (1) 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 0 0 0 3
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI 2 46 (37) 62
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 0 0
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI (1) 0 (3) 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 1 1 0 3
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 0 0 0 3
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI 2 45 (33) 58
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 (3) (13) (37) (17)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI $ 0 $ 0 $ 0 $ 0