XML 61 R45.htm IDEA: XBRL DOCUMENT v3.25.3
Fair Value of Financial Instruments - Financial Instruments Measured and Carried at Fair Value (Details) - USD ($)
$ in Millions
Sep. 30, 2025
Dec. 31, 2024
Financial Assets    
Total fixed maturity securities $ 5,666.5 $ 5,387.9
Equity securities 44.3 66.5
Limited partnership interests 1,137.8 1,121.3
Mortgage-backed securities    
Financial Assets    
Total fixed maturity securities 632.4 755.8
Other, including U.S. Treasury securities    
Financial Assets    
Total fixed maturity securities 359.9 357.6
Municipal bonds    
Financial Assets    
Total fixed maturity securities 1,198.2 1,150.8
Foreign government bonds    
Financial Assets    
Total fixed maturity securities 13.5 13.1
Corporate bonds    
Financial Assets    
Total fixed maturity securities 1,840.7 1,782.4
Other asset-backed securities    
Financial Assets    
Total fixed maturity securities 1,621.8 1,328.2
Recurring    
Financial Assets    
Limited partnership interests 33.5 28.9
Recurring | Carrying Amount    
Financial Assets    
Total fixed maturity securities 5,666.5 5,387.9
Equity securities 44.3 66.5
Limited partnership interests 33.5 28.9
Short-term investments 198.1 101.1
Other investments 19.5 18.5
Totals 5,961.9 5,602.9
Separate Account (variable annuity) assets 4,088.3 3,708.8
Financial Liabilities 75.3 79.6
Recurring | Carrying Amount | Mortgage-backed securities    
Financial Assets    
Total fixed maturity securities 632.3 755.8
Recurring | Carrying Amount | Other, including U.S. Treasury securities    
Financial Assets    
Total fixed maturity securities 359.9 357.6
Recurring | Carrying Amount | Municipal bonds    
Financial Assets    
Total fixed maturity securities 1,198.1 1,150.8
Recurring | Carrying Amount | Foreign government bonds    
Financial Assets    
Total fixed maturity securities 13.5 13.1
Recurring | Carrying Amount | Corporate bonds    
Financial Assets    
Total fixed maturity securities 1,840.8 1,782.4
Recurring | Carrying Amount | Other asset-backed securities    
Financial Assets    
Total fixed maturity securities 1,621.9 1,328.2
Recurring | Fair Value    
Financial Assets    
Total fixed maturity securities 5,666.5 5,387.9
Equity securities 44.3 66.5
Limited partnership interests 33.5 28.9
Short-term investments 198.1 101.1
Other investments 19.5 18.5
Totals 5,961.9 5,602.9
Separate Account (variable annuity) assets 4,088.3 3,708.8
Financial Liabilities 75.3 79.6
Recurring | Fair Value | Mortgage-backed securities    
Financial Assets    
Total fixed maturity securities 632.3 755.8
Recurring | Fair Value | Other, including U.S. Treasury securities    
Financial Assets    
Total fixed maturity securities 359.9 357.6
Recurring | Fair Value | Municipal bonds    
Financial Assets    
Total fixed maturity securities 1,198.1 1,150.8
Recurring | Fair Value | Foreign government bonds    
Financial Assets    
Total fixed maturity securities 13.5 13.1
Recurring | Fair Value | Corporate bonds    
Financial Assets    
Total fixed maturity securities 1,840.8 1,782.4
Recurring | Fair Value | Other asset-backed securities    
Financial Assets    
Total fixed maturity securities 1,621.9 1,328.2
Recurring | Fair Value | Level 1    
Financial Assets    
Total fixed maturity securities 30.3 32.4
Equity securities 1.4 1.4
Limited partnership interests 0.0 0.0
Short-term investments 198.1 101.1
Other investments 0.0 0.0
Totals 229.8 134.9
Separate Account (variable annuity) assets 4,088.3 3,708.8
Financial Liabilities 0.0 0.0
Recurring | Fair Value | Level 1 | Mortgage-backed securities    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 1 | Other, including U.S. Treasury securities    
Financial Assets    
Total fixed maturity securities 25.4 24.7
Recurring | Fair Value | Level 1 | Municipal bonds    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 1 | Foreign government bonds    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 1 | Corporate bonds    
Financial Assets    
Total fixed maturity securities 4.9 7.7
Recurring | Fair Value | Level 1 | Other asset-backed securities    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 2    
Financial Assets    
Total fixed maturity securities 5,158.8 4,855.6
Equity securities 38.7 60.9
Limited partnership interests 0.0 0.0
Short-term investments 0.0 0.0
Other investments 19.5 18.5
Totals 5,217.0 4,935.0
Separate Account (variable annuity) assets 0.0 0.0
Financial Liabilities 5.5 4.1
Recurring | Fair Value | Level 2 | Mortgage-backed securities    
Financial Assets    
Total fixed maturity securities 632.3 755.8
Recurring | Fair Value | Level 2 | Other, including U.S. Treasury securities    
Financial Assets    
Total fixed maturity securities 334.4 332.9
Recurring | Fair Value | Level 2 | Municipal bonds    
Financial Assets    
Total fixed maturity securities 1,120.1 1,075.9
Recurring | Fair Value | Level 2 | Foreign government bonds    
Financial Assets    
Total fixed maturity securities 13.5 13.1
Recurring | Fair Value | Level 2 | Corporate bonds    
Financial Assets    
Total fixed maturity securities 1,495.7 1,423.4
Recurring | Fair Value | Level 2 | Other asset-backed securities    
Financial Assets    
Total fixed maturity securities 1,562.8 1,254.5
Recurring | Fair Value | Level 3    
Financial Assets    
Total fixed maturity securities 477.4 499.9
Equity securities 4.2 4.2
Limited partnership interests 33.5 28.9
Short-term investments 0.0 0.0
Other investments 0.0 0.0
Totals 515.1 533.0
Separate Account (variable annuity) assets 0.0 0.0
Financial Liabilities 69.8 75.5
Recurring | Fair Value | Level 3 | Mortgage-backed securities    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 3 | Other, including U.S. Treasury securities    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 3 | Municipal bonds    
Financial Assets    
Total fixed maturity securities 78.1 74.9
Recurring | Fair Value | Level 3 | Foreign government bonds    
Financial Assets    
Total fixed maturity securities 0.0 0.0
Recurring | Fair Value | Level 3 | Corporate bonds    
Financial Assets    
Total fixed maturity securities 340.2 351.3
Recurring | Fair Value | Level 3 | Other asset-backed securities    
Financial Assets    
Total fixed maturity securities $ 59.1 $ 73.7