v3.26.1
Investments - Net Investment Income (Parenthetical) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Mar. 31, 2025
Schedule of Net Investment Income, Reported Amounts, by Category [Line Items]            
Investment, Type [Extensible Enumeration] Deposit Asset Underlying10 Insurance Agreement [Member] Deposit Asset Underlying10 Insurance Agreement [Member] Deposit Asset Underlying10 Insurance Agreement [Member] Deposit Asset Underlying10 Insurance Agreement [Member]    
Gains (losses) recognized for change in fair value of deposit asset underlying the 10% coinsurance agreement $ 0.0 $ 0.2 $ 0.0 $ 0.7    
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Realized Investment Gains (Losses) Realized Investment Gains (Losses) Realized Investment Gains (Losses) Realized Investment Gains (Losses)    
Percentage of coinsurance costs 10.00% 10.00% 10.00% 10.00% 10.00% 10.00%