v3.26.1
Net (Loss) Income Per Unrestricted Share - Reconciliation of Numerator and Denominator Used in Calculation (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Earnings Per Share [Abstract]        
Net (Loss) Income attributable to Kemper Corporation $ (464.8) $ 72.6 $ (466.5) $ 172.3
Weighted-Average Unrestricted Shares Outstanding (in shares) 58,866,000 63,938,900 58,804,700 63,912,900
Equity-based Compensation Equivalent Shares (in shares) 0 661,200 0 713,600
Weighted-Average Unrestricted Shares and Equivalent Shares Outstanding Assuming Dilution (in shares) 58,866,000 64,600,100 58,804,700 64,626,500
Basic Net (Loss) Income Per Unrestricted Share (in shares) $ (7.90) $ 1.13 $ (7.93) $ 2.69
Diluted Net (Loss) Income Per Unrestricted Share (in shares) $ (7.90) $ 1.12 $ (7.93) $ 2.66