v3.25.1
Policyholder Account Balance (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Policyholder Account Balance [Roll Forward]      
Policyholders' Account Balances $ 5,620.8   $ 5,633.7
Operating Segments      
Policyholder Account Balance [Roll Forward]      
Balance, beginning of year 5,470.0 $ 5,514.2  
Premiums received 40.2 40.2  
Policy Charges (59.9) [1] (60.6) [2]  
Surrenders and withdrawals (23.2) (22.8)  
Benefit payments (69.2) (79.5)  
Interest credited 95.6 95.6  
Other 2.5 3.2  
Balance, end of period 5,456.0 5,490.3  
Reserves in excess of account balance 164.8 148.7  
Policyholders' Account Balances 5,620.8 5,639.0  
Policyholder Account Balance, Reinsurance recoverable 4,086.8 4,097.9  
Net policyholders' account balances, after reinsurance recoverable $ 1,534.0 $ 1,541.1  
Weighted average crediting rate 7.20% 7.20%  
Net Amount at Risk $ 13,800.0 [3] $ 14,828.5 [4]  
Cash surrender value 5,393.0 5,425.2  
Colonial Life      
Policyholder Account Balance [Roll Forward]      
Balance, beginning of year 849.0 852.9  
Premiums received 19.4 20.5  
Policy Charges (17.6) [1] (18.3) [2]  
Surrenders and withdrawals (10.0) (9.7)  
Benefit payments (2.2) (2.1)  
Interest credited 8.5 8.6  
Other (0.1) 0.1  
Balance, end of period 847.0 852.0  
Reserves in excess of account balance 13.8 16.2  
Policyholders' Account Balances 860.8 868.2  
Policyholder Account Balance, Reinsurance recoverable 0.1 0.0  
Net policyholders' account balances, after reinsurance recoverable $ 860.7 $ 868.2  
Weighted average crediting rate 4.10% 4.10%  
Net Amount at Risk $ 8,057.8 [3] $ 8,621.0 [4]  
Cash surrender value 821.1 816.6  
Voluntary Benefits | Unum US      
Policyholder Account Balance [Roll Forward]      
Balance, beginning of year 568.8 578.6  
Premiums received 12.9 14.0  
Policy Charges (13.9) [1] (14.5) [2]  
Surrenders and withdrawals (8.9) (10.2)  
Benefit payments (1.6) (1.9)  
Interest credited 5.1 5.3  
Other 2.5 2.8  
Balance, end of period 564.9 574.1  
Reserves in excess of account balance 109.2 99.7  
Policyholders' Account Balances 674.1 673.8  
Policyholder Account Balance, Reinsurance recoverable 0.8 0.9  
Net policyholders' account balances, after reinsurance recoverable $ 673.3 $ 672.9  
Weighted average crediting rate 3.70% 3.70%  
Net Amount at Risk $ 4,040.4 [3] $ 4,393.5 [4]  
Cash surrender value 554.9 563.3  
Other Insurance Product Line | Closed Block      
Policyholder Account Balance [Roll Forward]      
Balance, beginning of year 4,052.2 4,082.7  
Premiums received 7.9 5.7  
Policy Charges (28.4) [1] (27.8) [2]  
Surrenders and withdrawals (4.3) (2.9)  
Benefit payments (65.4) (75.5)  
Interest credited 82.0 81.7  
Other 0.1 0.3  
Balance, end of period 4,044.1 4,064.2  
Reserves in excess of account balance 41.8 32.8  
Policyholders' Account Balances 4,085.9 4,097.0  
Policyholder Account Balance, Reinsurance recoverable 4,085.9 4,097.0  
Net policyholders' account balances, after reinsurance recoverable $ 0.0 $ 0.0  
Weighted average crediting rate 8.40% 8.30%  
Net Amount at Risk $ 1,701.8 [3] $ 1,814.0 [4]  
Cash surrender value $ 4,017.0 $ 4,045.3  
[1]
1Contracts included in the policyholders' account balances are generally charged a premium and/or monthly assessments on the basis of the account balance.
[2]
1Contracts included in the policyholders' account balances are generally charged a premium and/or monthly assessments on the basis of the account balance.
[3]
2For those guarantees of benefits that are payable in the event of death, the net amount at risk is generally defined as the current guaranteed minimum death benefit in excess of the current account balance at the balance sheet date.
[4]
2For those guarantees of benefits that are payable in the event of death, the net amount at risk is generally defined as the current guaranteed minimum death benefit in excess of the current account balance at the balance sheet date.