v3.26.1
Investments - Schedule of Unrealized Gains and Losses on Available for Sale Fixed Maturity and Short-Term Investments, at Fair Value (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments $ 664.2 $ 707.1
Gross unrealized gains 1.6 6.0
Gross unrealized losses (3.6) (1.1)
Fair value 662.2 712.0
Corporate    
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments 229.1 244.4
Gross unrealized gains 0.8 2.6
Gross unrealized losses (1.1) (0.1)
Fair value 228.8 246.9
US government and agency    
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments 131.0 123.6
Gross unrealized gains 0.1 1.0
Gross unrealized losses (0.5) (0.1)
Fair value 130.6 124.5
Non-US government and agency    
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments 226.8 247.0
Gross unrealized gains 0.5 1.5
Gross unrealized losses (1.6) (0.4)
Fair value 225.7 248.1
Residential mortgage-backed    
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments 54.3 55.5
Gross unrealized gains 0.1 0.6
Gross unrealized losses (0.3) (0.5)
Fair value 54.1 55.6
Commercial mortgage-backed    
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments 7.6 14.8
Gross unrealized gains 0.1 0.2
Gross unrealized losses 0.0 0.0
Fair value 7.7 15.0
Other asset-backed securities    
Debt Securities, Available-for-Sale [Line Items]    
Total fixed maturity and short-term investments 15.4 21.8
Gross unrealized gains 0.0 0.1
Gross unrealized losses (0.1) 0.0
Fair value $ 15.3 $ 21.9