v3.25.4
Property and Casualty Insurance Reserves - Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability (Details)
$ in Millions
Dec. 31, 2025
USD ($)
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance $ 2,704.5
Reinsurance Recoverables on Unpaid Losses and Allocated LAE 25.6
Unallocated LAE 210.1
Specialty Personal Automobile Insurance—Liability  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 1,637.6
Reinsurance Recoverables on Unpaid Losses and Allocated LAE 5.2
Specialty Personal Automobile Insurance—Liability | Variable Interest Entity, Primary Beneficiary  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 29.1
Specialty Personal Automobile Insurance—Physical Damage  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 23.5
Specialty Personal Automobile Insurance—Physical Damage | Variable Interest Entity, Primary Beneficiary  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 0.3
Commercial Automobile Insurance—Liability  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 888.0
Commercial Automobile Insurance—Physical Damage  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 15.8
Preferred Personal Automobile Insurance—Liability  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 92.6
Reinsurance Recoverables on Unpaid Losses and Allocated LAE 18.9
Preferred Personal Automobile Insurance—Physical Damage  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 0.1
Homeowners Insurance  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 17.0
Reinsurance Recoverables on Unpaid Losses and Allocated LAE 0.0
Other  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Net of Reinsurance 29.9
Reinsurance Recoverables on Unpaid Losses and Allocated LAE 1.5
Property and Casualty Insurance Product Line  
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]  
Property and Casualty Insurance Reserves, Gross of Reinsurance $ 2,940.2