XML 143 R117.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Retirement Plans and Other Postretirement Benefits - Narrative (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 USD ($) plan | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2006 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Number of supplemental defined benefit plans frozen | plan | 2 |  |  |
Pension cost (credit) | $ 9.3 | $ 8.9 | $ 9.1 |
Health reimbursement account, amount | 1.4 |  |  | $ 7.3
Health reimbursement accounts funding | 0.1 | $ 0.1 | $ 0.1 |
Defined Benefit Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected amortization of gain (loss) next year | 0.3 |  |  |
Supplemental Defined Benefit Plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected amortization of gain (loss) next year | $ 0.3 |  |  |
Qualified plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Number of retirement plans | plan | 2 |  |  |
Qualified plan | 401(k) plan | Defined Benefit Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Frozen supplemental defined benefit plans, vesting percentage | 100.00% |  |  |
Employer matching contribution as percent of employees' gross pay | 3.00% |  |  |
Percentage of employer match | 5.00% |  |  |
Vesting period for Company contributions | 5 years |  |  |
Nonqualified plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Number of retirement plans | plan | 3 |  |  |
Equity securities |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined benefit pension plan to approximate allocation | 50.00% |  |  |
Fixed income funds |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined benefit pension plan to approximate allocation | 50.00% |  |  |

X
- Definition Defined Contribution Plan, Vesting Period for Company Contributions + References No definition available. + Details
Name: | hmn_DefinedContributionPlanVestingPeriodforCompanyContributions
Namespace Prefix: | hmn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Frozen Supplemental Defined Benefit Plans, Vesting Percentage + References No definition available. + Details
Name: | hmn_FrozenSupplementalDefinedBenefitPlansVestingPercentage
Namespace Prefix: | hmn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Health reimbursement account balance. + References No definition available. + Details
Name: | hmn_HealthReimbursementAccountBalance
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Health reimbursement accounts funding. + References No definition available. + Details
Name: | hmn_HealthReimbursementAccountsFunding
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number Of Retirement Plans + References No definition available. + Details
Name: | hmn_NumberOfRetirementPlans
Namespace Prefix: | hmn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Supplemental Defined Benefit Plans Frozen + References No definition available. + Details
Name: | hmn_NumberOfSupplementalDefinedBenefitPlansFrozen
Namespace Prefix: | hmn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanExpectedAmortizationOfGainLossNextFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage employer matches of the employee's percentage contribution matched. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cost (reversal of cost) for pension benefits. Excludes other postretirement benefits. + References No definition available. + Details
Name: | us-gaap_PensionExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=us-gaap_QualifiedPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanNameAxis=hmn_FourZeroOneKPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=us-gaap_NonqualifiedPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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