Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Payable to brokers
Assets and Liabilities Measured at Fair Value [Abstract]
Liabilities	$ (82)	$ (70)
Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	22,117	24,845
States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	8,317	11,943
Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	7,193	7,585
Fixed maturities available-for-sale
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	37,627	44,373
Fixed maturities trading
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	70	7
Total fixed maturities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	37,697	44,380
Equity securities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	1,139	1,674
Short term and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	4,706	4,770
Receivables
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	19
Level 1 | Payable to brokers
Assets and Liabilities Measured at Fair Value [Abstract]
Liabilities	(82)	(70)
Level 1 | Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	120	140
Level 1 | States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Assets
Level 1 | Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Assets
Level 1 | Fixed maturities available-for-sale
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	120	140
Level 1 | Fixed maturities trading
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	1
Level 1 | Total fixed maturities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	121	140
Level 1 | Equity securities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	669	924
Level 1 | Short term and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	4,539	4,696
Level 1 | Receivables
Assets and Liabilities Measured at Fair Value [Abstract]
Assets
Level 2 | Payable to brokers
Assets and Liabilities Measured at Fair Value [Abstract]
Liabilities
Level 2 | Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	21,187	23,768
Level 2 | States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	8,274	11,887
Level 2 | Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	6,405	7,029
Level 2 | Fixed maturities available-for-sale
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	35,866	42,684
Level 2 | Fixed maturities trading
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	69	7
Level 2 | Total fixed maturities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	35,935	42,691
Level 2 | Equity securities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	435	721
Level 2 | Short term and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	167	74
Level 2 | Receivables
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	19
Level 3 | Payable to brokers
Assets and Liabilities Measured at Fair Value [Abstract]
Liabilities
Level 3 | Corporate bonds and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	810	937
Level 3 | States, municipalities and political subdivisions
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	43	56
Level 3 | Asset-backed
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	788	556
Level 3 | Fixed maturities available-for-sale
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	1,641	1,549
Level 3 | Fixed maturities trading
Assets and Liabilities Measured at Fair Value [Abstract]
Assets
Level 3 | Total fixed maturities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	1,641	1,549
Level 3 | Equity securities
Assets and Liabilities Measured at Fair Value [Abstract]
Assets	35	29
Level 3 | Short term and other
Assets and Liabilities Measured at Fair Value [Abstract]
Assets
Level 3 | Receivables
Assets and Liabilities Measured at Fair Value [Abstract]
Assets