v3.25.2
Market Risk Benefits - Net Asset (Liability) Balances and Changes in Valuation of the MRBs for Individual Variable Annuities (Details) - USD ($)
$ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Net asset (liability) balances and the changes in the valuation of the MRBs    
Balance at beginning of period, market risk benefits $ 137.4  
Balance at end of period, market risk benefits 111.4 $ 137.4
Retirement and Income Solutions | Individual variable annuities    
Net asset (liability) balances and the changes in the valuation of the MRBs    
Balance at beginning of period, market risk benefits 137.4 41.5
Effect of changes in nonperformance risk at beginning of period 19.0 7.7
Adjusted balance at beginning of period, market risk benefits 156.4 49.2
Interest accrual and expected policyholder behavior (27.6) (66.8)
Benefit payments   0.6
Changes in interest rates 0.4 100.4
Changes in equity markets 12.3 92.4
Changes in equity index volatility (9.6) 12.0
Actual policyholder behavior different from expected behavior (3.7) (12.7)
Changes in future expected policyholder behavior   (20.2)
Changes in other future expected assumptions   1.5
Adjusted balance at end of period, market risk benefits 128.2 156.4
Effect of changes in nonperformance risk at end of period 16.8 19.0
Balance at end of period, market risk benefits $ 111.4 $ 137.4
Weighted-average attained age of policyholders (years) 67 years 2 months 12 days 67 years 4 months 24 days
Net amount at risk $ 45.0 $ 46.8