XML 38 R89.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Employee Benefit Plans US Pension Assets, Fair Value Inputs (Details) (Pension Benefits, U.S. Plans, USD $) In Millions, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
--- | --- | ---
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | $ 1,469.4 unm_FairValueofInvestedPensionAssets | $ 1,586.4 unm_FairValueofInvestedPensionAssets
Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 550.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 598.3 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 796.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 884.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 122.1 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 103.7 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
United States Government and Government Agencies and Authorities |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 258.1 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 113.1 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
United States Government and Government Agencies and Authorities | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 243.5 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 105.7 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
United States Government and Government Agencies and Authorities | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 14.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 7.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
United States Government and Government Agencies and Authorities | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USTreasuryAndGovernmentMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Corporate Debt Securities |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 322.8 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 270.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Corporate Debt Securities | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 1.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 97.8 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Corporate Debt Securities | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 321.2 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 172.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Corporate Debt Securities | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
States, Municipalities, and Political Subdivisions |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 2.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 12.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
States, Municipalities, and Political Subdivisions | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
States, Municipalities, and Political Subdivisions | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 2.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 12.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
States, Municipalities, and Political Subdivisions | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Opportunistic Credits [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 147.8 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_OpportunisticCreditsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember |
Opportunistic Credits [Member] | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 62.8 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_OpportunisticCreditsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
Opportunistic Credits [Member] | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 85.0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_OpportunisticCreditsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
Opportunistic Credits [Member] | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_OpportunisticCreditsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
Private Equity Direct Investments |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 17.2 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 7.2 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Private Equity Direct Investments | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Private Equity Direct Investments | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Private Equity Direct Investments | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 17.2 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 7.2 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = unm_PrivateEquityDirectInvestmentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Private Equity Funds |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 34.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 29.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Private Equity Funds | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Private Equity Funds | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Private Equity Funds | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 34.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 29.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_PrivateEquityFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Hedge Funds |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 70.0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 66.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Hedge Funds | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Hedge Funds | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Hedge Funds | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 70.0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 66.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_HedgeFundsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Cash and Cash Equivalents |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 52.8 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember | 28.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember
Cash and Cash Equivalents | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 52.8 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 28.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Cash and Cash Equivalents | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Cash and Cash Equivalents | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_CashAndCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
U.S. Large Cap | Equity Securites |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 181.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember | 343.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember
U.S. Large Cap | Equity Securites | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
U.S. Large Cap | Equity Securites | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 181.4 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 343.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
U.S. Large Cap | Equity Securites | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USLargeCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
U.S. Mid Cap | Equity Securites |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 88.3 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember | 139.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember
U.S. Mid Cap | Equity Securites | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
U.S. Mid Cap | Equity Securites | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 88.3 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 139.6 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
U.S. Mid Cap | Equity Securites | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USMidCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
U.S. Small Cap | Equity Securites |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 118.7 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember | 231.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember
U.S. Small Cap | Equity Securites | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 118.7 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 231.9 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
U.S. Small Cap | Equity Securites | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
U.S. Small Cap | Equity Securites | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_USSmallCapMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
International Securities | Equity Securites |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 134.5 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember | 266.2 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember
International Securities | Equity Securites | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 71.0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 134.5 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
International Securities | Equity Securites | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 63.5 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 131.7 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
International Securities | Equity Securites | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_InternationalSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Emerging Markets | Equity Securites |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 40.0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember | 76.3 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember
Emerging Markets | Equity Securites | Fair Value, Inputs, Level 1 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member | 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Emerging Markets | Equity Securites | Fair Value, Inputs, Level 2 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | 40.0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member | 76.3 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Emerging Markets | Equity Securites | Fair Value, Inputs, Level 3 |  |
Defined Benefit Plans and Other Postretirement Benefit Plans |  |
Fair Value of Invested Pension Assets | $ 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member | $ 0 unm_FairValueofInvestedPensionAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_UnitedStatesPensionPlansOfUSEntityDefinedBenefitMember / us-gaap_EquitySecuritiesByEntitySizeAxis = unm_EmergingMarketsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member

X
- Definition Fair Value of Invested Pension Assets + References No definition available. + Details
Name: | unm_FairValueofInvestedPensionAssets
Namespace Prefix: | unm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=unm_OpportunisticCreditsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=unm_PrivateEquityDirectInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_HedgeFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_PrivateEquityFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByEntitySizeAxis=unm_EmergingMarketsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByEntitySizeAxis=unm_InternationalSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByEntitySizeAxis=unm_USLargeCapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByEntitySizeAxis=unm_USMidCapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByEntitySizeAxis=unm_USSmallCapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |