v3.25.4
Fair Value Measurements - Quantitative Information about Significant Unobservable Inputs (Details) - Valuation, Market Approach - Significant Unobservable Inputs (Level 3)
$ in Millions
Dec. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Other    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Total Fair Value $ 102.5 $ 66.9
Total Level 3 Fixed Maturity Investments    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Total Fair Value 339.4 205.2
Investment-grade | Investment-grade    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Total Fair Value 99.1 59.9
Non-investment-grade | Senior Debt    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Total Fair Value 102.6 42.7
Non-investment-grade | Junior Debt    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Total Fair Value $ 35.2 $ 35.7
Measurement Input, Discount Rate | Investment-grade | Investment-grade | Minimum    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Alternative investment, measurement input 0.016 0.034
Measurement Input, Discount Rate | Investment-grade | Investment-grade | Maximum    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Alternative investment, measurement input 0.111 0.116
Measurement Input, Discount Rate | Investment-grade | Investment-grade | Weighted-average Yield    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Alternative investment, measurement input 0.072 0.079
Senior Debt | Measurement Input, Discount Rate | Non-investment-grade | Minimum    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Debt instrument, measurement input 0.063 0.070
Senior Debt | Measurement Input, Discount Rate | Non-investment-grade | Maximum    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Debt instrument, measurement input 0.261 0.241
Senior Debt | Measurement Input, Discount Rate | Non-investment-grade | Weighted-average Yield    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Debt instrument, measurement input 0.091 0.100
Junior Debt | Measurement Input, Discount Rate | Non-investment-grade | Minimum    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Debt instrument, measurement input 0.085 0.095
Junior Debt | Measurement Input, Discount Rate | Non-investment-grade | Maximum    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Debt instrument, measurement input 0.260 0.310
Junior Debt | Measurement Input, Discount Rate | Non-investment-grade | Weighted-average Yield    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Debt instrument, measurement input 0.134 0.132