v3.25.2
Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Net unrealized investment gains (losses) on fixed maturity securities, net of tax        
Beginning of period     $ 1,287.5  
Other comprehensive income (loss) before reclassifications $ 2.1 $ 7.9 33.3 $ 28.8
Amounts reclassified from AOCI 3.2 1.7 3.1 2.5
Other comprehensive income 5.3 9.6 36.4 31.3
End of period 1,360.3 1,208.8 1,360.3 1,208.8
Pretax reclassification amounts from accumulated other comprehensive income (loss) (2.2) (3.2) (4.1) (3.9)
Pretax reclassification amounts from AOCI, tax (0.5) (0.7) (0.9) (0.8)
Total        
Net unrealized investment gains (losses) on fixed maturity securities, net of tax        
Beginning of period (222.4) (292.3) (253.5) (314.0)
End of period (217.1) (282.7) (217.1) (282.7)
Net Unrealized Investment Gains (Losses) on Fixed Maturity Securities        
Net unrealized investment gains (losses) on fixed maturity securities, net of tax        
Beginning of period (314.5) (348.0) (357.4) (328.3)
Other comprehensive income (loss) before reclassifications 1.4 (24.1) 44.4 (44.6)
Amounts reclassified from AOCI 3.2 1.7 3.1 2.5
Other comprehensive income 4.6 (22.4) 47.5 (42.1)
End of period (309.9) (370.4) (309.9) (370.4)
Net Reserve Remeasurements Attributable to Discount Rates        
Net unrealized investment gains (losses) on fixed maturity securities, net of tax        
Beginning of period 99.1 63.3 110.9 21.9
Other comprehensive income (loss) before reclassifications 0.7 32.0 (11.1) 73.4
Amounts reclassified from AOCI 0.0 0.0 0.0 0.0
Other comprehensive income 0.7 32.0 (11.1) 73.4
End of period 99.8 95.3 99.8 95.3
Net Funded Status of Benefit Plans        
Net unrealized investment gains (losses) on fixed maturity securities, net of tax        
Beginning of period (7.0) (7.6) (7.0) (7.6)
Other comprehensive income (loss) before reclassifications 0.0 0.0 0.0 0.0
Amounts reclassified from AOCI 0.0 0.0 0.0 0.0
Other comprehensive income 0.0 0.0 0.0 0.0
End of period $ (7.0) $ (7.6) $ (7.0) $ (7.6)