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Investment Securities - Cost and Amortized Cost Maturity Schedule (Details) - USD ($) $ in Millions | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Fixed Maturities, Excluding Asset-Backed Securities And Collateralized Loan Obligations |  |
Cost or Amortized Cost |  |
Due in one year or less | $ 455.3 | $ 205.8
Due after one year through five years | 1,349.8 | 1,494.5
Due after five years through ten years | 199.0 | 206.1
Due after ten years | 21.7 | 25.3
Carrying Value |  |
Due in one year or less | 455.2 | 203.9
Due after one year through five years | 1,354.1 | 1,478.7
Due after five years through ten years | 199.3 | 193.2
Due after ten years | 21.9 | 25.2
Mortgage and asset-backed securities and collateralized loan obligations |  |
Cost or Amortized Cost |  |
Mortgage and asset-backed securities and collateralized loan obligations | 749.0 | 637.5
Carrying Value |  |
Mortgage and asset-backed securities and collateralized loan obligations | 740.0 | 610.6
Fixed maturity investments |  |
Cost or Amortized Cost |  |
Total fixed maturity investments | 2,774.8 | 2,569.2
Carrying Value |  |
Total fixed maturity investments | $ 2,770.5 | $ 2,511.6

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