Reinsurance (Details) $ in Millions	6 Months Ended
Jun. 30, 2026 USD ($)
Atlantic States [Member]
Reinsurance [Abstract]
Percentage of share in results of pooled business owned by third party	80.00%
Donegal Mutual [Member]
Reinsurance [Abstract]
Percentage of share in results of pooled business owned by third party	20.00%
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	$ 22.0
Catastrophe reinsurance, set retention amount	$ 3.0
Percentage of accumulation of losses	100.00%
Additional coverage amount	$ 6.0
Property Insurance [Member]
Reinsurance [Abstract]
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	36.0
Catastrophe reinsurance, set retention amount	4.0
Liability Insurance [Member]
Reinsurance [Abstract]
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	69.0
Catastrophe reinsurance, set retention amount	6.0
Liability Insurance [Member] \| Donegal Mutual [Member]
Reinsurance [Abstract]
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	3.0
Catastrophe reinsurance, set retention amount	3.0
Workers' Compensation Insurance [Member]
Reinsurance [Abstract]
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	17.0
Catastrophe reinsurance, set retention amount	3.0
Third Party Reinsurance [Member]
Reinsurance [Abstract]
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	200.0
Catastrophe reinsurance, set retention amount	$ 25.0
Percentage of accumulation of losses	100.00%

The retention amount of Catastrophe reinsurance agreement contracts.

No definition available.

Name:	dgica_CatastropheReinsuranceAgreementContractsRetentionAmount
Namespace Prefix:	dgica_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The maximum amount of loss coverage under reinsurance agreement of property catastrophe.

+ References

No definition available.

+ Details

Name:	dgica_MaximumAmountOfLossCoverageUnderReinsuranceAgreementOfPropertyCatastrophe
Namespace Prefix:	dgica_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of share in results of pooled business owned by third party.

+ References

No definition available.

+ Details

Name:	dgica_PercentageOfShareInResultsOfPooledBusinessOwnedByThirdParty
Namespace Prefix:	dgica_
Data Type:	dtr:percentItemType
Balance Type:	na
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 825
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477351/944-825-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 825
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477351/944-825-50-1B

+ Details

Name:	us-gaap_CededCreditRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio of insurance contracts that are subject to reinsurance participation to all contracts in force.

+ References

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

+ Details

Name:	us-gaap_ContractsInForceSubjectToParticipationThroughReinsurancePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount per event of risk ceded to reinsurer in excess of risk undertaken originally by insurer that is not ceded to reinsurer.

+ References

+ Details

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

- Details

Name:	srt_ConsolidatedEntitiesAxis=dgica_AtlanticStatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=dgica_DonegalMutualInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_PropertyInsuranceProductLineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_ProfessionalLiabilityInsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_WorkersCompensationInsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CededCreditRiskAxis=dgica_ThirdPartyReinsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: