Fair Value Measurements (Fair Value Hierarchy For Assets Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	$ 13,791	$ 12,132
Separate accounts taxable fixed maturities	925	892
Total	25,701	22,845
Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	7,452	6,869
States, Municipalities and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	4,703	4,622
Government-Sponsored Enterprises
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	1,224	183
United States Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	200	191
Mortgage-backed
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	187	234
Foreign Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	25	33
Top Hat Savings Plan - Mutual Funds and Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Top Hat savings plan mutual funds and common equity (included in Other assets)	67	57
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	200	191
Total	10,908	9,702
Level 1 | Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 1 | States, Municipalities and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 1 | Government-Sponsored Enterprises
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 1 | United States Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	200	191
Level 1 | Mortgage-backed
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 1 | Foreign Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 1 | Top Hat Savings Plan - Mutual Funds and Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Top Hat savings plan mutual funds and common equity (included in Other assets)	67	57
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	13,591	11,941
Total	14,793	13,143
Level 2 | Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	7,452	6,869
Level 2 | States, Municipalities and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	4,703	4,622
Level 2 | Government-Sponsored Enterprises
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	1,224	183
Level 2 | United States Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 2 | Mortgage-backed
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	187	234
Level 2 | Foreign Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	25	33
Level 2 | Top Hat Savings Plan - Mutual Funds and Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Top Hat savings plan mutual funds and common equity (included in Other assets)	0	0
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Total	0	0
Level 3 | Corporate Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 3 | States, Municipalities and Political Subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 3 | Government-Sponsored Enterprises
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 3 | United States Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 3 | Mortgage-backed
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 3 | Foreign Government
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of fixed maturities	0	0
Level 3 | Top Hat Savings Plan - Mutual Funds and Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Top Hat savings plan mutual funds and common equity (included in Other assets)	0	0
Equity Securities | Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	10,641	9,454
Equity Securities | Nonredeemable Preferred Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	348	387
Equity Securities | Level 1 | Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	10,641	9,454
Equity Securities | Level 1 | Nonredeemable Preferred Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	0	0
Equity Securities | Level 2 | Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	0	0
Equity Securities | Level 2 | Nonredeemable Preferred Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	348	387
Equity Securities | Level 3 | Common Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	0	0
Equity Securities | Level 3 | Nonredeemable Preferred Equities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Total	0	0
Taxable Fixed Maturities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Separate accounts taxable fixed maturities	854	815
Taxable Fixed Maturities | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Separate accounts taxable fixed maturities	0	0
Taxable Fixed Maturities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Separate accounts taxable fixed maturities	854	815
Taxable Fixed Maturities | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Separate accounts taxable fixed maturities	$ 0	$ 0