<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.10.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>293</ContextCount>
  <ElementCount>301</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>52</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>4</UnitCount>
  <MyReports>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00000001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/cik0000355379-daei</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00000002 - Statement - Unaudited Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedBalanceSheets</Role>
      <ShortName>Unaudited Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00000003 - Statement - Unaudited Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Unaudited Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00000004 - Statement - Unaudited Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedStatementsOfOperations</Role>
      <ShortName>Unaudited Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00000005 - Statement - Unaudited Consolidated Statements of Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedStatementsOfComprehensiveIncomeLoss</Role>
      <ShortName>Unaudited Consolidated Statements of Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00000006 - Statement - Unaudited Consolidated Statement of Changes in Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedStatementOfChangesInEquity</Role>
      <ShortName>Unaudited Consolidated Statement of Changes in Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00000007 - Statement - Unaudited Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Unaudited Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>00000008 - Statement - Unaudited Consolidated Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnauditedConsolidatedStatementsOfCashFlowsParenthetical</Role>
      <ShortName>Unaudited Consolidated Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>00000009 - Disclosure - Organization</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/Organization</Role>
      <ShortName>Organization</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>00000010 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/BasisOfPresentation</Role>
      <ShortName>Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>00000011 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>00000012 - Disclosure - Acquisition of Direct Auto Insurance Company</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/AcquisitionOfDirectAutoInsuranceCompany</Role>
      <ShortName>Acquisition of Direct Auto Insurance Company</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>00000013 - Disclosure - Recent Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/RecentAccountingPronouncements</Role>
      <ShortName>Recent Accounting Pronouncements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>00000014 - Disclosure - Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/Investments</Role>
      <ShortName>Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>00000015 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>00000016 - Disclosure - Reinsurance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/Reinsurance</Role>
      <ShortName>Reinsurance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>00000017 - Disclosure - Deferred Policy Acquisition Costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/DeferredPolicyAcquisitionCosts</Role>
      <ShortName>Deferred Policy Acquisition Costs</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>00000018 - Disclosure - Unpaid Losses and Loss Adjustment Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnpaidLossesAndLossAdjustmentExpenses</Role>
      <ShortName>Unpaid Losses and Loss Adjustment Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>00000019 - Disclosure - Property and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/PropertyAndEquipment</Role>
      <ShortName>Property and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>00000020 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/RelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>00000021 - Disclosure - Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/BenefitPlans</Role>
      <ShortName>Benefit Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>00000022 - Disclosure - Line of Credit</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/LineOfCredit</Role>
      <ShortName>Line of Credit</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>00000023 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>00000024 - Disclosure - Operating Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/OperatingLeases</Role>
      <ShortName>Operating Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>00000025 - Disclosure - Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/Contingencies</Role>
      <ShortName>Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>00000026 - Disclosure - Common Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/CommonStock</Role>
      <ShortName>Common Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>00000027 - Disclosure - Stock Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensation</Role>
      <ShortName>Stock Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>00000028 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/EarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>00000029 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>00000030 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>00000031 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/SummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>00000032 - Disclosure - Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsTables</Role>
      <ShortName>Investments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/Investments</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>00000033 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/FairValueMeasurements</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>00000034 - Disclosure - Reinsurance (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/ReinsuranceTables</Role>
      <ShortName>Reinsurance (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/Reinsurance</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>00000035 - Disclosure - Deferred Policy Acquisition Costs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/DeferredPolicyAcquisitionCostsTables</Role>
      <ShortName>Deferred Policy Acquisition Costs (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/DeferredPolicyAcquisitionCosts</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>00000036 - Disclosure - Unpaid Losses and Loss Adjustment Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnpaidLossesAndLossAdjustmentExpensesTables</Role>
      <ShortName>Unpaid Losses and Loss Adjustment Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/UnpaidLossesAndLossAdjustmentExpenses</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>00000037 - Disclosure - Property and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/PropertyAndEquipmentTables</Role>
      <ShortName>Property and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/PropertyAndEquipment</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>00000038 - Disclosure - Related Party Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/RelatedPartyTransactionsTables</Role>
      <ShortName>Related Party Transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/RelatedPartyTransactions</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>00000039 - Disclosure - Common Stock (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/CommonStockTables</Role>
      <ShortName>Common Stock (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/CommonStock</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>00000040 - Disclosure - Stock Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensationTables</Role>
      <ShortName>Stock Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/StockBasedCompensation</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>00000041 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/EarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/EarningsPerShare</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>00000042 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SegmentInformationTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/SegmentInformation</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>00000043 - Disclosure - Organization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/OrganizationDetails</Role>
      <ShortName>Organization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/Organization</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>00000044 - Disclosure - Summary of Significant Accounting Policies (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Summary of Significant Accounting Policies (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/SummaryOfSignificantAccountingPoliciesPolicies</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>00000045 - Disclosure - Acquisition of Direct Auto Insurance Company (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/AcquisitionOfDirectAutoInsuranceCompanyNarrativeDetails</Role>
      <ShortName>Acquisition of Direct Auto Insurance Company (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/AcquisitionOfDirectAutoInsuranceCompany</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>00000046 - Disclosure - Recent Accounting Pronouncements (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/RecentAccountingPronouncementsNarrativeDetails</Role>
      <ShortName>Recent Accounting Pronouncements (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/RecentAccountingPronouncements</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>00000047 - Disclosure - Investments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsNarrativeDetails</Role>
      <ShortName>Investments (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/InvestmentsTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>00000048 - Disclosure - Investments (Schedule of amortized cost and estimated fair value of investment securities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsScheduleOfAmortizedCostAndEstimatedFairValueOfInvestmentSecuritiesDetails</Role>
      <ShortName>Investments (Schedule of amortized cost and estimated fair value of investment securities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/InvestmentsTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>00000049 - Disclosure - Investments (Schedule of Fixed Maturities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsScheduleOfFixedMaturitiesDetails</Role>
      <ShortName>Investments (Schedule of Fixed Maturities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/InvestmentsTables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>00000050 - Disclosure - Investments (Schedule of aggregate fair value and unrealized loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsScheduleOfAggregateFairValueAndUnrealizedLossDetails</Role>
      <ShortName>Investments (Schedule of aggregate fair value and unrealized loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/InvestmentsTables</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>00000051 - Disclosure - Investments (Schedule of Net Investment Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsScheduleOfNetInvestmentIncomeDetails</Role>
      <ShortName>Investments (Schedule of Net Investment Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/InvestmentsTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>00000052 - Disclosure - Investments (Schedule of components of Net realized capital gains on investments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/InvestmentsScheduleOfComponentsOfNetRealizedCapitalGainsOnInvestmentsDetails</Role>
      <ShortName>Investments (Schedule of components of Net realized capital gains on investments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/InvestmentsTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>00000053 - Disclosure - Fair Value Measurements (Schedule of assets, which are measured on a recurring basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/FairValueMeasurementsScheduleOfAssetsWhichAreMeasuredOnRecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements (Schedule of assets, which are measured on a recurring basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/FairValueMeasurementsTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>00000054 - Disclosure - Reinsurance (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/ReinsuranceNarrativeDetails</Role>
      <ShortName>Reinsurance (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/ReinsuranceTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>00000055 - Disclosure - Reinsurance (Schedule of reconciliation of direct to net premiums on both a written and an earned basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/ReinsuranceScheduleOfReconciliationOfDirectToNetPremiumsOnBothWrittenAndEarnedBasisDetails</Role>
      <ShortName>Reinsurance (Schedule of reconciliation of direct to net premiums on both a written and an earned basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/ReinsuranceTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>00000056 - Disclosure - Reinsurance (Schedule of reconciliation of direct to net losses and loss adjustment expenses) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/ReinsuranceScheduleOfReconciliationOfDirectToNetLossesAndLossAdjustmentExpensesDetails</Role>
      <ShortName>Reinsurance (Schedule of reconciliation of direct to net losses and loss adjustment expenses) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/ReinsuranceTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>00000057 - Disclosure - Deferred Policy Acquisition Costs (Schedule of deferred policy acquisition costs) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/DeferredPolicyAcquisitionCostsScheduleOfDeferredPolicyAcquisitionCostsDetails</Role>
      <ShortName>Deferred Policy Acquisition Costs (Schedule of deferred policy acquisition costs) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/DeferredPolicyAcquisitionCostsTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>00000058 - Disclosure - Unpaid Losses and Loss Adjustment Expenses (Schedule of liability for unpaid losses and loss adjustment expenses) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/UnpaidLossesAndLossAdjustmentExpensesScheduleOfLiabilityForUnpaidLossesAndLossAdjustmentExpensesDetails</Role>
      <ShortName>Unpaid Losses and Loss Adjustment Expenses (Schedule of liability for unpaid losses and loss adjustment expenses) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/UnpaidLossesAndLossAdjustmentExpensesTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>00000059 - Disclosure - Property and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/PropertyAndEquipmentDetails</Role>
      <ShortName>Property and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/PropertyAndEquipmentTables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>00000060 - Disclosure - Related Party Transactions (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/RelatedPartyTransactionsNarrativeDetails</Role>
      <ShortName>Related Party Transactions (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/RelatedPartyTransactionsTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>00000061 - Disclosure - Related Party Transactions (Schedule of impact of consolidating Battle Creek into our consolidated balance sheets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/RelatedPartyTransactionsScheduleOfImpactOfConsolidatingBattleCreekIntoOurConsolidatedBalanceSheetsDetails</Role>
      <ShortName>Related Party Transactions (Schedule of impact of consolidating Battle Creek into our consolidated balance sheets) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/RelatedPartyTransactionsTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>00000062 - Disclosure - Benefit Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/BenefitPlansDetails</Role>
      <ShortName>Benefit Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/BenefitPlans</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>00000063 - Disclosure - Line of Credit (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/LineOfCreditDetails</Role>
      <ShortName>Line of Credit (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/LineOfCredit</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>00000064 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/IncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/IncomeTaxes</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>00000065 - Disclosure - Operating Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/OperatingLeasesDetails</Role>
      <ShortName>Operating Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/OperatingLeases</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>00000066 - Disclosure - Common Stock (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/CommonStockNarrativeDetails</Role>
      <ShortName>Common Stock (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/CommonStockTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>00000067 - Disclosure - Common Stock (Schedule of changes in number of common stock) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/CommonStockScheduleOfChangesInNumberOfCommonStockDetails</Role>
      <ShortName>Common Stock (Schedule of changes in number of common stock) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/CommonStockTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>00000068 - Disclosure - Stock Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock Based Compensation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/StockBasedCompensationTables</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>00000069 - Disclosure - Stock Based Compensation (Schedule of Restricted Stock Outstanding) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensationScheduleOfRestrictedStockOutstandingDetails</Role>
      <ShortName>Stock Based Compensation (Schedule of Restricted Stock Outstanding) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/StockBasedCompensationTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>00000070 - Disclosure - Stock Based Compensation (Schedule of RSU activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensationScheduleOfRsuActivityDetails</Role>
      <ShortName>Stock Based Compensation (Schedule of RSU activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/StockBasedCompensationTables</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>00000071 - Disclosure - Stock Based Compensation (Schedule of Outstanding Performance Stock Units) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensationScheduleOfOutstandingPerformanceStockUnitsDetails</Role>
      <ShortName>Stock Based Compensation (Schedule of Outstanding Performance Stock Units) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/StockBasedCompensationTables</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>00000072 - Disclosure - Stock Based Compensation (Schedule of PSU Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/StockBasedCompensationScheduleOfPsuActivityDetails</Role>
      <ShortName>Stock Based Compensation (Schedule of PSU Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/StockBasedCompensationTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>00000073 - Disclosure - Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/EarningsPerShareDetails</Role>
      <ShortName>Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/EarningsPerShareTables</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>00000074 - Disclosure - Earnings per Share (Schedule of Calculations of Basic and Diluted Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/EarningsPerShareScheduleOfCalculationsOfBasicAndDilutedEarningsPerShareDetails</Role>
      <ShortName>Earnings per Share (Schedule of Calculations of Basic and Diluted Earnings Per Share) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="nodk-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>00000075 - Disclosure - Segment Information (Schedule of revenue by insurance product line) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://nodakmutual.com/role/SegmentInformationScheduleOfRevenueByInsuranceProductLineDetails</Role>
      <ShortName>Segment Information (Schedule of revenue by insurance product line) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://nodakmutual.com/role/SegmentInformationTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>nodk-20180630.xml</File>
    <File>nodk-20180630.xsd</File>
    <File>nodk-20180630_cal.xml</File>
    <File>nodk-20180630_def.xml</File>
    <File>nodk-20180630_lab.xml</File>
    <File>nodk-20180630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2018-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2018-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2018-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
