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Policyholder Account Balance (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024
Policyholder Account Balance [Roll Forward] |  |  |  |  |
Policyholders' Account Balance | $ 5,659.9 |  |  |  | $ 5,633.7
Operating Segments |  |  |  |  |
Policyholder Account Balance [Roll Forward] |  |  |  |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, Beginning of Year | 5,470.0 |  | $ 5,514.2 |  |
Policyholder Account Balance, Premium Received | 117.8 |  | 124.2 |  |
Policyholder Account Balance, Policy Charge | (175.7) | [1] | (170.8) | [2] |
Policyholder Account Balance, Surrender and Withdrawal | (70.7) |  | (64.5) |  |
Policyholder Account Balance, Benefit Payment | (147.1) |  | (167.9) |  |
Policyholder Account Balance, Interest Expense | 287.9 |  | 261.4 |  |
Policyholder Account Balance, Increase (Decrease) from Other Change | 8.0 |  | 8.6 |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, End of Period | 5,490.2 |  | 5,505.2 |  |
Policyholder Account Balance, Reserves in excess of Account Balance | 169.7 |  | 156.1 |  |
Policyholders' Account Balance | 5,659.9 |  | 5,661.3 |  |
Policyholder Account Balance, Reinsurance recoverable | 4,135.9 |  | 4,124.3 |  |
Policyholder Account Balance, After reinsurance recoverable | $ 1,524.0 |  | $ 1,537.0 |  |
Policyholder Account Balance, Weighted Average Crediting Rate | 7.30% |  | 6.50% |  |
Policyholder Account Balance, Net Amount at Risk | $ 13,228.0 | [3] | $ 14,234.1 | [4] |
Policyholder Account Balance, Cash Surrender Value | 5,421.7 |  | 5,440.2 |  |
Unum US | Voluntary Benefits |  |  |  |  |
Policyholder Account Balance [Roll Forward] |  |  |  |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, Beginning of Year | 568.8 |  | 578.6 |  |
Policyholder Account Balance, Premium Received | 37.3 |  | 40.7 |  |
Policyholder Account Balance, Policy Charge | (41.0) | [1] | (42.9) | [2] |
Policyholder Account Balance, Surrender and Withdrawal | (30.0) |  | (24.3) |  |
Policyholder Account Balance, Benefit Payment | (4.6) |  | (4.8) |  |
Policyholder Account Balance, Interest Expense | 15.1 |  | 15.7 |  |
Policyholder Account Balance, Increase (Decrease) from Other Change | 7.2 |  | 7.6 |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, End of Period | 552.8 |  | 570.6 |  |
Policyholder Account Balance, Reserves in excess of Account Balance | 114.6 |  | 104.4 |  |
Policyholders' Account Balance | 667.4 |  | 675.0 |  |
Policyholder Account Balance, Reinsurance recoverable | 0.7 |  | 0.8 |  |
Policyholder Account Balance, After reinsurance recoverable | $ 666.7 |  | $ 674.2 |  |
Policyholder Account Balance, Weighted Average Crediting Rate | 3.60% |  | 3.70% |  |
Policyholder Account Balance, Net Amount at Risk | $ 3,822.1 | [3] | $ 4,210.4 | [4] |
Policyholder Account Balance, Cash Surrender Value | 542.5 |  | 560.4 |  |
Colonial Life |  |  |  |  |
Policyholder Account Balance [Roll Forward] |  |  |  |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, Beginning of Year | 849.0 |  | 852.9 |  |
Policyholder Account Balance, Premium Received | 56.3 |  | 60.2 |  |
Policyholder Account Balance, Policy Charge | (52.2) | [1] | (54.2) | [2] |
Policyholder Account Balance, Surrender and Withdrawal | (28.3) |  | (30.4) |  |
Policyholder Account Balance, Benefit Payment | (5.9) |  | (6.0) |  |
Policyholder Account Balance, Interest Expense | 25.4 |  | 25.6 |  |
Policyholder Account Balance, Increase (Decrease) from Other Change | 0.1 |  | 0.2 |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, End of Period | 844.4 |  | 848.3 |  |
Policyholder Account Balance, Reserves in excess of Account Balance | 12.9 |  | 14.5 |  |
Policyholders' Account Balance | 857.3 |  | 862.8 |  |
Policyholder Account Balance, Reinsurance recoverable | 0.0 |  | 0.0 |  |
Policyholder Account Balance, After reinsurance recoverable | $ 857.3 |  | $ 862.8 |  |
Policyholder Account Balance, Weighted Average Crediting Rate | 4.10% |  | 4.10% |  |
Policyholder Account Balance, Net Amount at Risk | $ 7,795.1 | [3] | $ 8,325.0 | [4] |
Policyholder Account Balance, Cash Surrender Value | 821.9 |  | 817.1 |  |
Closed Block | Other Insurance Product Line |  |  |  |  |
Policyholder Account Balance [Roll Forward] |  |  |  |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, Beginning of Year | 4,052.2 |  | 4,082.7 |  |
Policyholder Account Balance, Premium Received | 24.2 |  | 23.3 |  |
Policyholder Account Balance, Policy Charge | (82.5) | [1] | (73.7) | [2] |
Policyholder Account Balance, Surrender and Withdrawal | (12.4) |  | (9.8) |  |
Policyholder Account Balance, Benefit Payment | (136.6) |  | (157.1) |  |
Policyholder Account Balance, Interest Expense | 247.4 |  | 220.1 |  |
Policyholder Account Balance, Increase (Decrease) from Other Change | 0.7 |  | 0.8 |  |
Policyholder Account Balance, before Reserves in excess of Account Balance, End of Period | 4,093.0 |  | 4,086.3 |  |
Policyholder Account Balance, Reserves in excess of Account Balance | 42.2 |  | 37.2 |  |
Policyholders' Account Balance | 4,135.2 |  | 4,123.5 |  |
Policyholder Account Balance, Reinsurance recoverable | 4,135.2 |  | 4,123.5 |  |
Policyholder Account Balance, After reinsurance recoverable | $ 0.0 |  | $ 0.0 |  |
Policyholder Account Balance, Weighted Average Crediting Rate | 8.50% |  | 7.40% |  |
Policyholder Account Balance, Net Amount at Risk | $ 1,610.8 | [3] | $ 1,698.7 | [4] |
Policyholder Account Balance, Cash Surrender Value | $ 4,057.3 |  | $ 4,062.7 |  |
[1] | 1 Contracts included in the policyholders' account balances are generally charged a premium and/or monthly assessments on the basis of the account balance.
[2] | 1 Contracts included in the policyholders' account balances are generally charged a premium and/or monthly assessments on the basis of the account balance.
[3] | 2 For 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] | 2 For 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.

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- Definition Amount of cash to be paid to policyholder upon termination and surrender of long-duration contract issued by insurance entity. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Subparagraph (b)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-7A Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 29F -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-29F + Details
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