Name:	hmn_AssumedInsurancePremiumsAndContractChargesEarned
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Insurance premiums written and contract deposits for all insurance contracts assumed from other insurers as a result of reinsurance arrangements.

No definition available.

Name:	hmn_AssumedInsurancePremiumsWrittenAndContractDeposits
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Insurance premiums and contract charges assumed and earned by another insurer as a result of reinsurance arrangements.

No definition available.

Name:	hmn_CededInsurancePremiumsAndContractChargesEarned
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Insurance premiums written and contract deposits assumed by another insurer as a result of reinsurance arrangements.

No definition available.

Name:	hmn_CededInsurancePremiumsWrittenAndContractDeposits
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The sum of insurance premiums earned, premiums earned on the income statement for all insurance contracts before subtracting any amounts ceded to another insurer or adding premiums assumed from other insurers, plus contract charges earned on investment and universal life-type contracts.

No definition available.

Name:	hmn_DirectInsurancePremiumsAndContractChargesEarned
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The sum of insurance premiums written for all insurance contracts before subtracting any amounts ceded to another insurer or adding premiums assumed from other insurers plus contract deposits on investment and universal life-type contracts.

No definition available.

Name:	hmn_DirectInsurancePremiumsWrittenAndContractDeposits
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The sum of insurance premiums written for all insurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers, plus contract deposits on investment and universal life-type contracts.

No definition available.

Name:	hmn_InsurancePremiumsWrittenAndContractDeposits
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The sum of insurance premiums earned, premiums earned on the income statement for all insurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers, plus contract charges earned on investment and universal life-type contracts.

No definition available.

Name:	hmn_PremiumsAndContractChargesEarnedNetAmount
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Reinsurance, Assumed from Other Companies [Abstract]

No definition available.

Name:	hmn_ReinsuranceAssumedfromOtherCompaniesAbstract
Namespace Prefix:	hmn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reinsurance, Ceded to Other Companies [Abstract]

No definition available.

Name:	hmn_ReinsuranceCededtoOtherCompaniesAbstract
Namespace Prefix:	hmn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reinsurance, Gross Amounts [Abstract]

No definition available.

Name:	hmn_ReinsuranceGrossAmountsAbstract
Namespace Prefix:	hmn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reinsurance, Net Amount [Abstract]

No definition available.

Name:	hmn_ReinsuranceNetAmountAbstract
Namespace Prefix:	hmn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

Name:	us-gaap_PolicyholderBenefitsAndClaimsIncurredGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-14

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-11

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 11
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-11

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479868/944-20-45-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Name:	us-gaap_PolicyholderBenefitsAndClaimsIncurredNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of policy benefits and costs incurred for policies assumed.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479838/944-20-50-3

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Name:	us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-14

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-11

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479838/944-20-50-3

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1