v3.26.1
Fair Value Measurements - Fair Value Recurring Basis, Unobservable Input (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Liabilities          
Assets, Fair Value Disclosure $ 50,372   $ 50,372   $ 50,655
Significant
Unobservable
Inputs
(Level 3)          
Liabilities          
Assets, Fair Value Disclosure $ 4,361   $ 4,361   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 $ 4,152 $ 3,224 $ 4,028 $ 2,992  
Total realized/unrealized gains (losses), Included in net income (11) (12) (46) (16)  
Total realized/unrealized gains (losses), Included in OCI 6 48 (34) 67  
Purchases 1,114 580 1,784 1,034  
Settlements (662) (149) (944) (300)  
Sales (99) (75) (189) (86)  
Transfers into Level 3 2 8 4 81  
Transfers out of Level 3 (141) (189) (242) (337)  
Ending balance $ 4,361 $ 3,435 $ 4,361 $ 3,435  
Liabilities          
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)  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Equity securities, at fair value          
Assets          
Beginning balance $ 123 $ 91 $ 106 $ 87  
Total realized/unrealized gains (losses), Included in net income (1) 0 (2) (1)  
Total realized/unrealized gains (losses), Included in OCI 0 0 0 0  
Purchases 12 2 30 10  
Settlements 0 0 0 (3)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 (10) 0 (10) 0  
Ending balance 124 93 124 93  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Short-term investments          
Assets          
Beginning balance 688 59 382 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 626 57 1,061 67  
Settlements (518) 0 (559) (49)  
Sales (87) 0 (174) 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 0 0 0 0  
Ending balance 709 116 709 116  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 3,211 2,879 3,372 2,610  
Total realized/unrealized gains (losses), Included in net income (7) 1 (7) 2  
Total realized/unrealized gains (losses), Included in OCI 6 48 (33) 67  
Purchases 476 519 692 949  
Settlements (142) (146) (378) (241)  
Sales (12) (75) (15) (86)  
Transfers into Level 3 2 8 4 81  
Transfers out of Level 3 (131) (189) (232) (337)  
Ending balance 3,403 3,045 3,403 3,045  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Fair Value Option, Other Eligible Items | Total Fixed Maturities, AFS          
Assets          
Beginning balance 130   168    
Total realized/unrealized gains (losses), Included in net income (3)   (37)    
Total realized/unrealized gains (losses), Included in OCI 0   0    
Purchases 0   1    
Settlements (2)   (7)    
Sales 0   0    
Transfers into Level 3 0   0    
Transfers out of Level 3 0   0    
Ending balance 125   125    
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | ABS | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 163 56 167 22  
Total realized/unrealized gains (losses), Included in net income 0 0 0 0  
Total realized/unrealized gains (losses), Included in OCI (1) 0 (3) 1  
Purchases 18 39 30 73  
Settlements (5) (3) (8) (4)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 0 0 (11) 0  
Ending balance 175 92 175 92  
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 233 233 217 116  
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 75 20 182 228  
Settlements 0 (18) 0 (19)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 (108) (165) (198) (255)  
Ending balance 200 70 200 70  
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   195   197  
Total realized/unrealized gains (losses), Included in net income   (13)   (17)  
Total realized/unrealized gains (losses), Included in OCI   0   0  
Purchases   2   8  
Settlements   (3)   (7)  
Sales   0   0  
Transfers into Level 3   0   0  
Transfers out of Level 3   0   0  
Ending balance   181   181  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | CMBS | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 116 150 115 167  
Total realized/unrealized gains (losses), Included in net income (7) (1) (7) (1)  
Total realized/unrealized gains (losses), Included in OCI 5 1 4 4  
Purchases 0 0 0 0  
Settlements (12) (13) (12) (13)  
Sales (7) (8) (7) (10)  
Transfers into Level 3 2 8 4 43  
Transfers out of Level 3 0 0 0 (53)  
Ending balance 97 137 97 137  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | Corporate | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 2,694 2,401 2,866 2,281  
Total realized/unrealized gains (losses), Included in net income 0 2 0 3  
Total realized/unrealized gains (losses), Included in OCI 2 47 (33) 62  
Purchases 372 460 469 624  
Settlements (124) (109) (355) (198)  
Sales (5) (67) (8) (76)  
Transfers into Level 3 0 0 0 38  
Transfers out of Level 3 (23) 0 (23) 0  
Ending balance 2,916 2,734 2,916 2,734  
Significant
Unobservable
Inputs
(Level 3) | Fair Value, Measurements, Recurring | RMBS | Available-for-sale Securities [Member] | Total Fixed Maturities, AFS          
Assets          
Beginning balance 5 39 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 11 0 11 24  
Settlements (1) (3) (3) (7)  
Sales 0 0 0 0  
Transfers into Level 3 0 0 0 0  
Transfers out of Level 3 0 (24) 0 (29)  
Ending balance 15 $ 12 15 $ 12  
Quoted Prices in
Active Markets
for Identical
Assets
(Level 1)          
Liabilities          
Assets, Fair Value Disclosure 1,164   1,164   966
Significant
Observable
Inputs
(Level 2)          
Liabilities          
Assets, Fair Value Disclosure $ 44,847   $ 44,847   $ 45,661