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Schedule I - Summary Of Investments (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
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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 |

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