v3.26.1
Investment Securities - Cost and Amortized Cost Maturity Schedule (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Fixed Maturities, Excluding Asset-Backed Securities And Collateralized Loan Obligations    
Cost or Amortized Cost    
Due in one year or less $ 511.0 $ 455.3
Due after one year through five years 1,368.6 1,349.8
Due after five years through ten years 257.0 199.0
Due after ten years 14.7 21.7
Carrying Value    
Due in one year or less 511.1 455.2
Due after one year through five years 1,359.2 1,354.1
Due after five years through ten years 253.6 199.3
Due after ten years 14.5 21.9
Mortgage and asset-backed securities and collateralized loan obligations    
Cost or Amortized Cost    
Mortgage and asset-backed securities and collateralized loan obligations 761.9 749.0
Carrying Value    
Mortgage and asset-backed securities and collateralized loan obligations 747.7 740.0
Fixed maturity investments    
Cost or Amortized Cost    
Total fixed maturity investments 2,913.2 2,774.8
Carrying Value    
Total fixed maturity investments $ 2,886.1 $ 2,770.5