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Investments - Distribution of Fixed Maturity Securities by Expected Maturity (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2025 | Dec. 31, 2024
Amortized Cost, net |  |
Due in 1 year or less | $ 238.2 |
Due after 1 year through 5 years | 1,406.8 |
Due after 5 years through 10 years | 1,509.7 |
Due after 10 years through 20 years | 1,550.9 |
Due after 20 years | 1,152.1 |
Amortized Cost, net | 5,857.7 | $ 5,842.5
Fair Value |  |
Due in 1 year or less | 235.9 |
Due after 1 year through 5 years | 1,383.0 |
Due after 5 years through 10 years | 1,453.4 |
Due after 10 years through 20 years | 1,405.6 |
Due after 20 years | 979.8 |
Total | $ 5,457.7 | $ 5,387.9
Percent of Total Fair Value |  |
Due in 1 year Or less (percent) | 4.30% |
Due after 1 year through 5 years (percent) | 25.30% |
Due after 5 years through 10 years (percent) | 26.60% |
Due after 10 years through 20 years (percent) | 25.80% |
Due after 20 years (percent) | 18.00% |
Total (percent) | 100.00% |
Average option-adjusted duration, in years | 5 years 6 months |

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