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Organization - Additional Information (Detail) | 6 Months Ended
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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%

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- Definition Percentage of voting power owned by major shareholder. + References No definition available. + Details
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- 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
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- 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
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