v3.26.3
Investment Securities - Cost and Amortized Cost Maturity Schedule (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Fixed Maturities, Excluding Asset-Backed Securities And Collateralized Loan Obligations    
Cost or Amortized Cost    
Due in one year or less $ 345.5 $ 455.3
Due after one year through five years 1,658.1 1,349.8
Due after five years through ten years 310.1 199.0
Due after ten years 21.7 21.7
Carrying Value    
Due in one year or less 345.5 455.2
Due after one year through five years 1,610.0 1,354.1
Due after five years through ten years 293.4 199.3
Due after ten years 20.7 21.9
Mortgage and asset-backed securities and collateralized loan obligations    
Cost or Amortized Cost    
Mortgage and asset-backed securities and collateralized loan obligations 808.9 749.0
Carrying Value    
Mortgage and asset-backed securities and collateralized loan obligations 771.2 740.0
Fixed maturity investments    
Cost or Amortized Cost    
Total fixed maturity investments 3,144.3 2,774.8
Carrying Value    
Total fixed maturity investments $ 3,040.8 $ 2,770.5