v3.25.4
Schedule 1 - Investments Other Than Investments in Related Parties (Details)
$ in Millions
Dec. 31, 2025
USD ($)
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost $ 9,402.0
Amount Carried in Balance Sheet 8,669.6
Fixed Maturities:  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 7,475.7
Fair Value 6,743.3
Amount Carried in Balance Sheet 6,743.3
United States Government and Government Agencies and Authorities  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 702.0
Fair Value 622.4
Amount Carried in Balance Sheet 622.4
States and Political Subdivisions  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 1,437.3
Fair Value 1,253.2
Amount Carried in Balance Sheet 1,253.2
Foreign Governments  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 10.7
Fair Value 11.0
Amount Carried in Balance Sheet 11.0
Other Bonds and Notes  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 4,089.8
Fair Value 3,650.3
Amount Carried in Balance Sheet 3,650.3
Redeemable Preferred Stocks  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 9.8
Fair Value 10.2
Amount Carried in Balance Sheet 10.2
Collateralized Loan Obligations  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 850.8
Fair Value 843.0
Amount Carried in Balance Sheet 843.0
Other Mortgage- and Asset-backed  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 375.3
Fair Value 353.2
Amount Carried in Balance Sheet 353.2
Equity Securities at Fair Value:  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 306.4
Fair Value 306.4
Amount Carried in Balance Sheet 306.4
Preferred Stocks  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 19.2
Fair Value 19.2
Amount Carried in Balance Sheet 19.2
Common Stock  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 65.0
Fair Value 65.0
Amount Carried in Balance Sheet 65.0
Other Equity Interests  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 222.2
Fair Value 222.2
Amount Carried in Balance Sheet 222.2
Equity Method Limited Liability Investments at Cost Plus Cumulative Undistributed Earnings  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 176.0
Amount Carried in Balance Sheet 176.0
Short-term Investments  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 313.5
Amount Carried in Balance Sheet 313.5
Company-Owned Life Insurance  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 579.2
Amount Carried in Balance Sheet 579.2
Loans to Policyholders  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 279.9
Amount Carried in Balance Sheet 279.9
Other Investments  
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]  
Amortized Cost 271.3
Amount Carried in Balance Sheet $ 271.3