v3.24.2
Fair Value Measurements (Details) - Fair Value Hierarchy - Recurring basis [Member] - USD ($)
$ in Millions
Jun. 30, 2024
Dec. 31, 2023
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis $ 79,851 $ 78,433
Fixed maturities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 79,188 77,807
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 5,940 6,368
Obligations of U.S. states, municipalities and political subdivisions [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 27,256 28,506
Debt securities issued by foreign governments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 880 1,006
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 10,201 7,818
Corporate and all other bonds [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 34,911 34,109
Equity securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 644 608
Common stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 594 560
Non-redeemable preferred stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 50 48
Other Investments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 19 18
Level 1 [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 6,579 6,955
Level 1 [Member] | Fixed maturities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 5,957 6,368
Level 1 [Member] | U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 5,940 6,368
Level 1 [Member] | Obligations of U.S. states, municipalities and political subdivisions [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 1 [Member] | Debt securities issued by foreign governments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 1 [Member] | Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 17 0
Level 1 [Member] | Corporate and all other bonds [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 1 [Member] | Equity securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 603 569
Level 1 [Member] | Common stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 587 553
Level 1 [Member] | Non-redeemable preferred stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 16 16
Level 1 [Member] | Other Investments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 19 18
Level 2 [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 72,928 71,183
Level 2 [Member] | Fixed maturities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 72,925 71,181
Level 2 [Member] | U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 2 [Member] | Obligations of U.S. states, municipalities and political subdivisions [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 27,256 28,506
Level 2 [Member] | Debt securities issued by foreign governments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 880 1,006
Level 2 [Member] | Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 10,139 7,818
Level 2 [Member] | Corporate and all other bonds [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 34,650 33,851
Level 2 [Member] | Equity securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 3 2
Level 2 [Member] | Common stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 2 [Member] | Non-redeemable preferred stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 3 2
Level 2 [Member] | Other Investments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 3 [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 344 295
Level 3 [Member] | Fixed maturities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 306 258
Level 3 [Member] | U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 3 [Member] | Obligations of U.S. states, municipalities and political subdivisions [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 3 [Member] | Debt securities issued by foreign governments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 0 0
Level 3 [Member] | Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 45 0
Level 3 [Member] | Corporate and all other bonds [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 261 258
Level 3 [Member] | Equity securities [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 38 37
Level 3 [Member] | Common stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 7 7
Level 3 [Member] | Non-redeemable preferred stock [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 31 30
Level 3 [Member] | Investment in non-public common and preferred equity securities where the fair value estimate is determined either internally or by an external fund manager [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis 38 37
Level 3 [Member] | Other Investments [Member]    
Level within the fair value hierarchy at which the Company's financial assets and financial liabilities are measured    
Total invested assets measured on a recurring basis $ 0 $ 0