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 retention amount of loss reinsurance agreement contracts.

+ References

No definition available.

+ Details

Name:	dgica_LossReinsuranceAgreementContractsRetentionAmount
Namespace Prefix:	dgica_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of share in results of pooled business subsidiary.

+ References

No definition available.

+ Details

Name:	dgica_PercentageOfShareInResultsOfPooledBusinessSubsidiary
Namespace Prefix:	dgica_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of reinsurance claims receivable from Michigan Catastrophic Claims Association.

+ References

No definition available.

+ Details

Name:	dgica_ReceivableFromReinsuranceClaims
Namespace Prefix:	dgica_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of reinsurance claims return estimated surplus from Michigan Catastrophic Claims Association.

+ References

No definition available.

+ Details

Name:	dgica_ReturnFromEstimatedSurplus
Namespace Prefix:	dgica_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_ReinsurancePolicyAndProceduresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387

+ Details

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

- 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:

- Details

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

- Details

Name:	dei_LegalEntityAxis=dgica_DonegalMutualMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Reinsurance (Details) - USD ($)	6 Months Ended
Reinsurance (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021	Nov. 30, 2021
Reinsurance Transactions [Abstract]
Loss reinsurance agreement contracts retention amount	$ 2,000,000.0
Return from estimated surplus			$ 3,000,000,000.0
Receivable from reinsurance claims	0	$ 18,112,800
Property Insurance [Member]
Reinsurance Transactions [Abstract]
Catastrophe reinsurance, set retention amount	2,000,000.0
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	38,000,000.0
Liability Insurance [Member]
Reinsurance Transactions [Abstract]
Catastrophe reinsurance, set retention amount	2,000,000.0
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	73,000,000.0
Workers' Compensation Insurance [Member]
Reinsurance Transactions [Abstract]
Catastrophe reinsurance, set retention amount	2,000,000.0
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	$ 18,000,000.0
Third Party Reinsurance [Member]
Reinsurance Transactions [Abstract]
Percentage of accumulation of losses	100.00%
Catastrophe reinsurance, set retention amount	$ 15,000,000.0
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	$ 185,000,000.0
Atlantic States [Member]
Reinsurance Transactions [Abstract]
Percentage of share in results of pooled business subsidiary	80.00%
Donegal Mutual [Member]
Reinsurance Transactions [Abstract]
Percentage of share in results of pooled business owned by third party	20.00%
Percentage of accumulation of losses	100.00%
Catastrophe reinsurance, set retention amount	$ 2,000,000.0
Maximum amount of loss coverage under reinsurance agreement of property catastrophe	13,000,000.0
Additional coverage amount	$ 5,000,000.0