v3.26.3
Fair Value Measurements - Fair Value Recurring Basis, Unobservable Input (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Liabilities          
Assets, Fair Value Disclosure $ 50,943   $ 50,943   $ 50,655
Significant
Unobservable
Inputs
(Level 3)          
Liabilities          
Assets, Fair Value Disclosure $ 4,332   $ 4,332   4,028
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring          
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]          
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration] Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent  
Assets          
Beginning balance $ 4,361 $ 3,435 $ 4,028 $ 2,992  
Total realized/unrealized gains (losses), Included in net income (7) 7 (53) (9)  
Total realized/unrealized gains (losses), Included in OCI (32) 4 (66) 71  
Purchases 786 830 2,570 1,864  
Settlements (590) (487) (1,534) (787)  
Sales (100) (12) (289) (98)  
Transfers into Level 3 0 2 4 83  
Transfers out of Level 3 (86) (37) (328) (374)  
Ending balance $ 4,332 $ 3,742 $ 4,332 $ 3,742  
Liabilities          
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  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Equity securities, at fair value          
Assets          
Beginning balance $ 124 $ 93 $ 106 $ 87  
Total realized/unrealized gains (losses), Included in net income 0 0 (2) (1)  
Total realized/unrealized gains (losses), Included in OCI 0 0 0 0  
Purchases 0 29 30 39  
Settlements 0 (16) 0 (19)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 0 0 (10) 0  
Ending balance 124 106 124 106  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Short-term investments          
Assets          
Beginning balance 709 116 382 98  
Total realized/unrealized gains (losses), Included in net income 0 0 0 0  
Total realized/unrealized gains (losses), Included in OCI 0 0 (1) 0  
Purchases 217 201 1,278 268  
Settlements (351) (110) (910) (159)  
Sales (87) 0 (261) 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 0 0 0 0  
Ending balance 488 207 488 207  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 3,403 3,045 3,372 2,610  
Total realized/unrealized gains (losses), Included in net income (7) 0 (14) 2  
Total realized/unrealized gains (losses), Included in OCI (32) 4 (65) 71  
Purchases 568 593 1,260 1,542  
Settlements (236) (357) (614) (598)  
Sales (13) (12) (28) (98)  
Transfers into Level 3 0 2 4 83  
Transfers out of Level 3 (86) (37) (318) (374)  
Ending balance 3,597 3,238 3,597 3,238  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Fair Value Option, Other Eligible Items | Total Fixed Maturities, AFS          
Assets          
Beginning balance 125   168    
Total realized/unrealized gains (losses), Included in net income 0   (37)    
Total realized/unrealized gains (losses), Included in OCI 0   0    
Purchases 1   2    
Settlements (3)   (10)    
Sales 0   0    
Transfers into Level 3 0   0    
Transfers out of Level 3 0   0    
Ending balance 123   123    
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | ABS | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 175 92 167 22  
Total realized/unrealized gains (losses), Included in net income 0 0 0 0  
Total realized/unrealized gains (losses), Included in OCI (7) 0 (10) 1  
Purchases 86 13 116 86  
Settlements (5) (12) (13) (16)  
Sales (1) 0 (1) 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 0 (10) (11) (10)  
Ending balance 248 83 248 83  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Collateralized Loan Obligations [Member] | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 200 70 217 116  
Total realized/unrealized gains (losses), Included in net income 0 0 0 0  
Total realized/unrealized gains (losses), Included in OCI 0 0 (1) 0  
Purchases 190 119 372 347  
Settlements 0 (10) 0 (29)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 (75) (15) (273) (270)  
Ending balance 315 164 315 164  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Collateralized Loan Obligations [Member] | Fair Value Option, Other Eligible Items | Total Fixed Maturities, AFS          
Assets          
Beginning balance   181   197  
Total realized/unrealized gains (losses), Included in net income   7   (10)  
Total realized/unrealized gains (losses), Included in OCI   0   0  
Purchases   7   15  
Settlements   (4)   (11)  
Sales   0   0  
Transfers into Level 3   0   0  
Transfers out of Level 3   0   0  
Ending balance   191   191  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | CMBS | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 97 137 115 167  
Total realized/unrealized gains (losses), Included in net income (4) 0 (11) (1)  
Total realized/unrealized gains (losses), Included in OCI 1 2 5 6  
Purchases 0 0 0 0  
Settlements (1) (8) (13) (21)  
Sales (11) 0 (18) (10)  
Transfers into Level 3 0 2 4 45  
Transfers out of Level 3 0 0 0 (53)  
Ending balance 82 133 82 133  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Corporate | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 2,916 2,734 2,866 2,281  
Total realized/unrealized gains (losses), Included in net income (3) 0 (3) 3  
Total realized/unrealized gains (losses), Included in OCI (26) 2 (59) 64  
Purchases 239 448 708 1,072  
Settlements (229) (325) (584) (523)  
Sales (1) (12) (9) (88)  
Transfers into Level 3 0 0 0 38  
Transfers out of Level 3 0 (12) (23) (12)  
Ending balance 2,896 2,835 2,896 2,835  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | RMBS | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 15 12 7 24  
Total realized/unrealized gains (losses), Included in net income 0 0 0 0  
Total realized/unrealized gains (losses), Included in OCI 0 0 0 0  
Purchases 53 13 64 37  
Settlements (1) (2) (4) (9)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 (11) 0 (11) (29)  
Ending balance 56 $ 23 56 $ 23  
Quoted Prices in
Active Markets
for Identical
Assets
(Level 1)          
Liabilities          
Assets, Fair Value Disclosure 889   889   966
Significant
Observable
Inputs
(Level 2)          
Liabilities          
Assets, Fair Value Disclosure $ 45,722   $ 45,722   $ 45,661