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Investments - Distribution of Fixed Maturity Securities by Expected Maturity (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2024 | Dec. 31, 2023
Amortized Cost, net |  |
Due in 1 year or less | $ 296.6 |
Due after 1 year through 5 years | 1,497.3 |
Due after 5 years through 10 years | 1,524.5 |
Due after 10 years through 20 years | 1,452.8 |
Due after 20 years | 1,045.3 |
Amortized Cost, net | 5,816.5 | $ 5,652.9
Fair Value |  |
Due in 1 year or less | 292.4 |
Due after 1 year through 5 years | 1,451.5 |
Due after 5 years through 10 years | 1,449.0 |
Due after 10 years through 20 years | 1,289.1 |
Due after 20 years | 863.4 |
Total | $ 5,345.4 | $ 5,235.3
Percent of Total Fair Value |  |
Due in 1 year Or less (percent) | 5.50% |
Due after 1 year through 5 years (percent) | 27.10% |
Due after 5 years through 10 years (percent) | 27.10% |
Due after 10 years through 20 years (percent) | 24.10% |
Due after 20 years (percent) | 16.20% |
Total (percent) | 100.00% |
Average option-adjusted duration, in years | 5 years 9 months 18 days |

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