XML 58 R40.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value of Financial Instruments - Financial Instruments Measured and Carried at Fair Value (Details) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | $ (1,466) | $ 1,196 |  |
Net unrealized investment gains (losses) included in other comprehensive income |  | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 |  |
Purchases |  | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 |  |
Issuances | 1,332 | 3,389 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 243,868 | 248,757 | $ 230,257 | $ 212,104
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | 78,486 | 64,261 | 80,733 | 59,393
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 25,600 | 50,171 |  |
Transfers into Level 3 | 0 | 0 |  |
Net realized investment gains (losses) included in net income related to financial assets | 3 | 0 |  |
Net realized gains (losses) included in net income related to financial liabilities | (2,222) | 2,308 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 6,861 |  |
Transfers out of Level 3 | 0 | 0 |  |
Financial Liabilities |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 3 | 0 |  |
Sales |  | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 |  |
Settlements |  | 0 |  |
FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPaydownsAndMaturities | 1,357 | 829 |  |
Paydowns, maturities and distributions | 10,523 | 7,853 |  |
Short-term investments |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 0 | 0 | 0 | 751
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 | 0 |  |
Net realized investment gains (losses) included in net income related to financial assets | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 751 |  |
Financial Liabilities |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 |  |
Paydowns, maturities and distributions | 0 | 0 |  |
Municipal bonds |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 443 | 1,871 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 49,748 | 53,462 | 49,328 | 46,497
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 | 5,214 |  |
Net realized investment gains (losses) included in net income related to financial assets | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 0 |  |
Financial Liabilities |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 |  |
Paydowns, maturities and distributions | 23 | 120 |  |
Corporate bonds |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | (887) | 96 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 78,780 | 82,495 | 72,979 | 60,191
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 10,778 | 29,918 |  |
Net realized investment gains (losses) included in net income related to financial assets | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 6,110 |  |
Financial Liabilities |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 |  |
Paydowns, maturities and distributions | 4,090 | 1,600 |  |
Equity securities |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 6 | 6 | 6 | $ 6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 | 0 |  |
Net realized investment gains (losses) included in net income related to financial assets | 3 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 | 0 |  |
Financial Liabilities |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 3 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 | 0 |  |
Paydowns, maturities and distributions | 0 | $ 0 |  |
Carrying Amount |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 7,813,029 |  | 7,950,184 |
Financial Liabilities |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 518 |  | 594 |
Other policyholder funds, embedded derivatives | 78,486 |  | 80,733 |
Carrying Amount | Recurring |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 7,634,682 |  | 7,724,075 |
Carrying Amount | Short-term investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 22,194 |  | 62,593 |
Carrying Amount | Mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 710,958 |  | 696,725 |
Carrying Amount | Other, including U.S. Treasury securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 761,967 |  | 735,408 |
Carrying Amount | Municipal bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 1,861,304 |  | 1,893,253 |
Carrying Amount | Foreign government bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 99,041 |  | 102,738 |
Carrying Amount | Corporate bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 2,481,270 |  | 2,578,954 |
Carrying Amount | Other mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 1,720,142 |  | 1,716,997 |
Carrying Amount | Equity securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 131,023 |  | 135,466 |
Carrying Amount | Other investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 25,130 |  | 28,050 |
Fair Value |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 7,813,029 |  | 7,950,184 |
Financial Liabilities |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 518 |  | 594 |
Other policyholder funds, embedded derivatives | 78,486 |  | 80,733 |
Fair Value | Recurring |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 7,634,682 |  | 7,724,075 |
Fair Value | Short-term investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 22,194 |  | 62,593 |
Fair Value | Mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 710,958 |  | 696,725 |
Fair Value | Other, including U.S. Treasury securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 761,967 |  | 735,408 |
Fair Value | Municipal bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 1,861,304 |  | 1,893,253 |
Fair Value | Foreign government bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 99,041 |  | 102,738 |
Fair Value | Corporate bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 2,481,270 |  | 2,578,954 |
Fair Value | Other mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 1,720,142 |  | 1,716,997 |
Fair Value | Equity securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 131,023 |  | 135,466 |
Fair Value | Other investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 25,130 |  | 28,050 |
Fair Value | Level 1 |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 129,046 |  | 172,539 |
Financial Liabilities |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 0 |  | 0 |
Other policyholder funds, embedded derivatives | 0 |  | 0 |
Fair Value | Level 1 | Recurring |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 26,982 |  | 27,738 |
Fair Value | Level 1 | Short-term investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 22,194 |  | 62,593 |
Fair Value | Level 1 | Mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 1 | Other, including U.S. Treasury securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 13,249 |  | 13,393 |
Fair Value | Level 1 | Municipal bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 1 | Foreign government bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 1 | Corporate bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 13,733 |  | 14,345 |
Fair Value | Level 1 | Other mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 1 | Equity securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 79,870 |  | 82,208 |
Fair Value | Level 1 | Other investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 2 |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 7,440,115 |  | 7,547,388 |
Financial Liabilities |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 518 |  | 594 |
Other policyholder funds, embedded derivatives | 0 |  | 0 |
Fair Value | Level 2 | Recurring |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 7,363,838 |  | 7,466,086 |
Fair Value | Level 2 | Short-term investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 2 | Mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 707,842 |  | 693,375 |
Fair Value | Level 2 | Other, including U.S. Treasury securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 748,718 |  | 722,015 |
Fair Value | Level 2 | Municipal bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 1,811,556 |  | 1,843,925 |
Fair Value | Level 2 | Foreign government bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 99,041 |  | 102,738 |
Fair Value | Level 2 | Corporate bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 2,388,757 |  | 2,491,630 |
Fair Value | Level 2 | Other mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 1,607,924 |  | 1,612,403 |
Fair Value | Level 2 | Equity securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 51,147 |  | 53,252 |
Fair Value | Level 2 | Other investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 25,130 |  | 28,050 |
Fair Value | Level 3 |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 243,868 |  | 230,257 |
Financial Liabilities |  |  |  |
Investment contract and life policy reserves, embedded derivatives | 0 |  | 0 |
Other policyholder funds, embedded derivatives | 78,486 |  | 80,733 |
Fair Value | Level 3 | Recurring |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 243,862 |  | 230,251 |
Fair Value | Level 3 | Short-term investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 3 | Mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 3,116 |  | 3,350 |
Fair Value | Level 3 | Other, including U.S. Treasury securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 3 | Municipal bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 49,748 |  | 49,328 |
Fair Value | Level 3 | Foreign government bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 0 |  | 0 |
Fair Value | Level 3 | Corporate bonds |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 78,780 |  | 72,979 |
Fair Value | Level 3 | Other mortgage-backed securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 112,218 |  | 104,594 |
Fair Value | Level 3 | Equity securities |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | 6 |  | 6 |
Fair Value | Level 3 | Other investments |  |  |  |
U.S. Government and federally sponsored agency obligations: |  |  |  |
Investments | $ 0 |  | $ 0 |

X
- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset paydowns and maturities. + References No definition available. + Details
Name: | hmn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPaydownsAndMaturities
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Paydowns And Maturities + References No definition available. + Details
Name: | hmn_Fairvaluemeasurementwithunobservableinputsreconciliationrecurringbasisliabilitypaydownsandmaturities
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value disclosure of accrued obligation to policyholders that relates to insured events under other insurance contracts. + References No definition available. + Details
Name: | hmn_LiabilityForFuturePolicyBenefitsDerivativeInstrumentsFairValueDisclosure
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value of the liability as of the policyholders for funds held that are returnable under the terms of insurance contracts that were not separately reported. + References No definition available. + Details
Name: | hmn_OtherPolicyholderFundsDerivativeInstrumentsFairValueDisclosure
Namespace Prefix: | hmn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition U.S. government and federally sponsored agency obligations. + References No definition available. + Details
Name: | hmn_UsGovernmentAndFederallySponsoredAgencyObligationsAbstract
Namespace Prefix: | hmn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of transfers of financial instrument classified as a liability into level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of issuances of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of sales of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=hmn_OtherIncludingUsTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ForeignGovernmentDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=hmn_OtherInvestmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
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: |