Schedule I - Summary Of Investments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Cost	$ 2,652
Investments	2,664
Short-term investments, at cost (approximates fair value)	2,197	$ 2,041
Other Investments	475	568
Available-for-sale Securities	1,710	1,395
Investments	2,664	2,593
Municipal Bonds [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	72	44
Available-for-sale Securities	72	43
Corporate Debt Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	785	659
Available-for-sale Securities	745	598
Debt Security, Government, Non-US [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	105	85
Available-for-sale Securities	100	76
Residential Mortgage-Backed Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	239	230
Available-for-sale Securities	250	238
Collateralized Debt Obligations [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	139	141
Available-for-sale Securities	139	137
Asset-backed Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	301	227
Available-for-sale Securities	303	224
Short-term Investments [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	426	507
Available-for-sale Securities	426	507
U S Government Obligations [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	85
Available-for-sale Securities	82
US Government Debt Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	85	68
Available-for-sale Securities	82	65
ShortTermInvestmentsMember, including Pledged
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	452
Available-for-sale Securities	452
Corporate Obligations, Excluding Related Party Investments
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	785
Available-for-sale Securities	745
Other Investments [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	432
Available-for-sale Securities	463
Other Investments [Member] | Fixed Income Funds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities	475
Commercial Mortgage Backed Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	19	15
Available-for-sale Securities	19	0
Available-for-sale Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	24
Available-for-sale Securities	27
Fixed Income Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short-term investments, at cost (approximates fair value)	1,744	$ 1,469
Fair Value Amount, Excluding Related Party Investments [Domain]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Investments	$ 2,652