XML 39 R28.htm IDEA: XBRL DOCUMENT v3.21.2

Organization - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2021 Segment
Business Acquisition [Line Items]
Operations commenced date	Aug. 26, 1986
Number of operating segments	3
Atlantic States [Member]
Business Acquisition [Line Items]
Voting power percentage of outstanding common stock	70.00%
Percentage of share in results of pooled business subsidiary	80.00%
Donegal Mutual [Member]
Business Acquisition [Line Items]
Premiums and losses related to certain products	100.00%
Class A Common Stock [Member]
Business Acquisition [Line Items]
Stock ownership percentage held by major shareholder	41.00%
Class B Common Stock [Member]
Business Acquisition [Line Items]
Stock ownership percentage held by major shareholder	84.00%

X

- Definition

Percentage of share in results of pooled business subsidiary.

+ References

No definition available.

+ Details

Name:	dgica_PercentageOfShareInResultsOfPooledBusinessSubsidiary
Namespace Prefix:	dgica_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage of voting power owned by major shareholder.

+ References

No definition available.

+ Details

Name:	dgica_PercentageOfVotingPowerOwnedByMajorShareholder
Namespace Prefix:	dgica_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Stock ownership percentage held by major shareholder.

+ References

No definition available.

+ Details

Name:	dgica_StockOwnershipPercentageHeldByMajorShareholder
Namespace Prefix:	dgica_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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

X

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Date the operations of the entity commenced, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_OperationsCommencedDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage of assumed premium earned to premium earned after effects of reinsurance, as disclosed in supplementary reinsurance information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column F))
-URI http://asc.fasb.org/extlink&oid=120401096&loc=d3e574992-122915

+ Details

Name:	us-gaap_PremiumsPercentageAssumedToNet
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: