<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>998</ContextCount>
  <ElementCount>555</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>147</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>15</UnitCount>
  <MyReports>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>9952151 - Statement - Condensed Consolidated Balance Sheets (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedBalanceSheetsUnaudited</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952152 - Statement - Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952153 - Statement - Condensed Consolidated Statements of Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedStatementsofIncomeUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952155 - Statement - Condensed Consolidated Statements of Changes in Shareholders??? Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Changes in Shareholders??? Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952156 - Statement - Condensed Consolidated Statements of Changes in Shareholders??? Equity (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedStatementsofChangesinShareholdersEquityUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Changes in Shareholders??? Equity (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - MERGER</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/MERGER</Role>
      <ShortName>MERGER</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - INVESTMENT SECURITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIES</Role>
      <ShortName>INVESTMENT SECURITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSES</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - LEASES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LEASES</Role>
      <ShortName>LEASES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETS</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - SHARE-BASED COMPENSATION PLANS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANS</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - DEPOSITS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DEPOSITS</Role>
      <ShortName>DEPOSITS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTS</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - SUBORDINATED NOTES</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.orrstown.com/role/SUBORDINATEDNOTES</Role>
      <ShortName>SUBORDINATED NOTES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - SHAREHOLDERS' EQUITY AND REGULATORY CAPITAL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREHOLDERSEQUITYANDREGULATORYCAPITAL</Role>
      <ShortName>SHAREHOLDERS' EQUITY AND REGULATORY CAPITAL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - EARNINGS PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/EARNINGSPERSHARE</Role>
      <ShortName>EARNINGS PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9952171 - Disclosure - FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FINANCIALINSTRUMENTSWITHOFFBALANCESHEETRISK</Role>
      <ShortName>FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9952172 - Disclosure - FAIR VALUE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUE</Role>
      <ShortName>FAIR VALUE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9952173 - Disclosure - SEGMENT REPORTING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SEGMENTREPORTING</Role>
      <ShortName>SEGMENT REPORTING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9952174 - Disclosure - CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CONTINGENCIES</Role>
      <ShortName>CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - MERGER (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/MERGERTables</Role>
      <ShortName>MERGER (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/MERGER</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - INVESTMENT SECURITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIESTables</Role>
      <ShortName>INVESTMENT SECURITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/INVESTMENTSECURITIES</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESTables</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSES</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - LEASES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LEASESTables</Role>
      <ShortName>LEASES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/LEASES</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETSTables</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETS</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - INCOME TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INCOMETAXESTables</Role>
      <ShortName>INCOME TAXES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/INCOMETAXES</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - SHARE-BASED COMPENSATION PLANS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANSTables</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANS</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - DEPOSITS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DEPOSITSTables</Role>
      <ShortName>DEPOSITS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/DEPOSITS</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTSTables</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTS</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - SUBORDINATED NOTES (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.orrstown.com/role/SUBORDINATEDNOTESTables</Role>
      <ShortName>SUBORDINATED NOTES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/SUBORDINATEDNOTES</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - SHAREHOLDERS' EQUITY AND REGULATORY CAPITAL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREHOLDERSEQUITYANDREGULATORYCAPITALTables</Role>
      <ShortName>SHAREHOLDERS' EQUITY AND REGULATORY CAPITAL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/SHAREHOLDERSEQUITYANDREGULATORYCAPITAL</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - EARNINGS PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/EARNINGSPERSHARETables</Role>
      <ShortName>EARNINGS PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/EARNINGSPERSHARE</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FINANCIALINSTRUMENTSWITHOFFBALANCESHEETRISKTables</Role>
      <ShortName>FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/FINANCIALINSTRUMENTSWITHOFFBALANCESHEETRISK</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - FAIR VALUE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUETables</Role>
      <ShortName>FAIR VALUE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/FAIRVALUE</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - MERGER - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/MERGERNarrativeDetails</Role>
      <ShortName>MERGER - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - MERGER - Summary of Purchase Price Consideration Paid (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/MERGERSummaryofPurchasePriceConsiderationPaidDetails</Role>
      <ShortName>MERGER - Summary of Purchase Price Consideration Paid (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - MERGER - Summary of Consideration Paid and Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/MERGERSummaryofConsiderationPaidandEstimatedFairValueofAssetsAcquiredandLiabilitiesAssumedDetails</Role>
      <ShortName>MERGER - Summary of Consideration Paid and Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - MERGER - Summary of Fair Value of Acquired PCD Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/MERGERSummaryofFairValueofAcquiredPCDLoansDetails</Role>
      <ShortName>MERGER - Summary of Fair Value of Acquired PCD Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - INVESTMENT SECURITIES - Amortized Cost and Fair Values of AFS Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIESAmortizedCostandFairValuesofAFSSecuritiesDetails</Role>
      <ShortName>INVESTMENT SECURITIES - Amortized Cost and Fair Values of AFS Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - INVESTMENT SECURITIES - Summary of AFS Securities with Unrealized Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIESSummaryofAFSSecuritieswithUnrealizedLossesDetails</Role>
      <ShortName>INVESTMENT SECURITIES - Summary of AFS Securities with Unrealized Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - INVESTMENT SECURITIES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIESNarrativeDetails</Role>
      <ShortName>INVESTMENT SECURITIES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - INVESTMENT SECURITIES - Summary of Amortized Cost and Fair Values of AFS Securities by Contractual Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIESSummaryofAmortizedCostandFairValuesofAFSSecuritiesbyContractualMaturityDetails</Role>
      <ShortName>INVESTMENT SECURITIES - Summary of Amortized Cost and Fair Values of AFS Securities by Contractual Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - INVESTMENT SECURITIES - Summary of Proceeds from Sales of AFS Securities and Gross Gains and Gross Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INVESTMENTSECURITIESSummaryofProceedsfromSalesofAFSSecuritiesandGrossGainsandGrossLossesDetails</Role>
      <ShortName>INVESTMENT SECURITIES - Summary of Proceeds from Sales of AFS Securities and Gross Gains and Gross Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESNarrativeDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Loan Portfolio, Excluding Residential Loans Held for Sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESSummaryofLoanPortfolioExcludingResidentialLoansHeldforSaleDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Loan Portfolio, Excluding Residential Loans Held for Sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Amortized Cost of the Loan Portfolio, by Year of Origination, Loan Class, and Credit Quality (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESAmortizedCostoftheLoanPortfoliobyYearofOriginationLoanClassandCreditQualityDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Amortized Cost of the Loan Portfolio, by Year of Origination, Loan Class, and Credit Quality (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Amortized Cost of Nonaccrual Loans by Class, With and Without Loan Reserves (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESAmortizedCostofNonaccrualLoansbyClassWithandWithoutLoanReservesDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Amortized Cost of Nonaccrual Loans by Class, With and Without Loan Reserves (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Amortized Cost Basis of Collateral Dependent Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESAmortizedCostBasisofCollateralDependentLoansDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Amortized Cost Basis of Collateral Dependent Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Effect of Loans Modified (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESEffectofLoansModifiedDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Effect of Loans Modified (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loan Portfolio Summarized by Aging Categories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESLoanPortfolioSummarizedbyAgingCategoriesDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Loan Portfolio Summarized by Aging Categories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - LOANS AND ALLOWANCE FOR CREDIT LOSSES - Activity in Allowance for Loan Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LOANSANDALLOWANCEFORCREDITLOSSESActivityinAllowanceforLoanLossesDetails</Role>
      <ShortName>LOANS AND ALLOWANCE FOR CREDIT LOSSES - Activity in Allowance for Loan Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - LEASES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LEASESNarrativeDetails</Role>
      <ShortName>LEASES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - LEASES - Summary of Information Related to Operating Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LEASESSummaryofInformationRelatedtoOperatingLeasesDetails</Role>
      <ShortName>LEASES - Summary of Information Related to Operating Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - LEASES - Summary of Maturities of Operating Leases Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/LEASESSummaryofMaturitiesofOperatingLeasesLiabilitiesDetails</Role>
      <ShortName>LEASES - Summary of Maturities of Operating Leases Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETSNarrativeDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Changes in Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETSSummaryofChangesinGoodwillDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Changes in Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Changes in Other Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETSSummaryofChangesinOtherIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Changes in Other Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Components of Other Identifiable Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETSSummaryofComponentsofOtherIdentifiableIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Components of Other Identifiable Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Estimated Aggregate Amortization Expense for Other Identifiable Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/GOODWILLANDOTHERINTANGIBLEASSETSSummaryofEstimatedAggregateAmortizationExpenseforOtherIdentifiableIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Estimated Aggregate Amortization Expense for Other Identifiable Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9955551 - Disclosure - INCOME TAXES - Summary of Income Tax Expense (Benefit) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/INCOMETAXESSummaryofIncomeTaxExpenseBenefitDetails</Role>
      <ShortName>INCOME TAXES - Summary of Income Tax Expense (Benefit) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9955552 - Disclosure - SHARE-BASED COMPENSATION PLANS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANSNarrativeDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9955553 - Disclosure - SHARE-BASED COMPENSATION PLANS - Summary of Nonvested Restricted Shares Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANSSummaryofNonvestedRestrictedSharesActivityDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS - Summary of Nonvested Restricted Shares Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9955554 - Disclosure - SHARE-BASED COMPENSATION PLANS - Summary of Restricted Shares Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANSSummaryofRestrictedSharesCompensationExpenseDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS - Summary of Restricted Shares Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9955555 - Disclosure - SHARE-BASED COMPENSATION PLANS - Summary of Outstanding Stock Options Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANSSummaryofOutstandingStockOptionsActivityDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS - Summary of Outstanding Stock Options Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9955556 - Disclosure - SHARE-BASED COMPENSATION PLANS - Summary of Employee Stock Purchase Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREBASEDCOMPENSATIONPLANSSummaryofEmployeeStockPurchasePlanDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS - Summary of Employee Stock Purchase Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9955557 - Disclosure - DEPOSITS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DEPOSITSNarrativeDetails</Role>
      <ShortName>DEPOSITS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9955558 - Disclosure - DEPOSITS - Summary of Composition of Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DEPOSITSSummaryofCompositionofDepositsDetails</Role>
      <ShortName>DEPOSITS - Summary of Composition of Deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>9955559 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTSNarrativeDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>9955560 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Fair Value of Derivative Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTSSummaryofFairValueofDerivativeInstrumentsDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Fair Value of Derivative Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>9955561 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Carrying Amount and Cumulative Adjustment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTSSummaryofCarryingAmountandCumulativeAdjustmentDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Carrying Amount and Cumulative Adjustment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>9955562 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Effect of Derivative Financial Instruments on OCI and Net Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTSSummaryofEffectofDerivativeFinancialInstrumentsonOCIandNetIncomeDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Effect of Derivative Financial Instruments on OCI and Net Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>9955563 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Components of Interest Rate Swaps (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/DERIVATIVEFINANCIALINSTRUMENTSSummaryofComponentsofInterestRateSwapsDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Components of Interest Rate Swaps (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>9955564 - Disclosure - SUBORDINATED NOTES - Narrative (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.orrstown.com/role/SUBORDINATEDNOTESNarrativeDetails</Role>
      <ShortName>SUBORDINATED NOTES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>9955565 - Disclosure - SUBORDINATED NOTES - Summary of Maturities of Subordinated Notes and Trust Preferred Debt (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.orrstown.com/role/SUBORDINATEDNOTESSummaryofMaturitiesofSubordinatedNotesandTrustPreferredDebtDetails</Role>
      <ShortName>SUBORDINATED NOTES - Summary of Maturities of Subordinated Notes and Trust Preferred Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>9955566 - Disclosure - SHAREHOLDERS??? EQUITY AND REGULATORY CAPITAL - Summary of Actual and Required Capital Amounts and Ratios (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREHOLDERSEQUITYANDREGULATORYCAPITALSummaryofActualandRequiredCapitalAmountsandRatiosDetails</Role>
      <ShortName>SHAREHOLDERS??? EQUITY AND REGULATORY CAPITAL - Summary of Actual and Required Capital Amounts and Ratios (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>9955567 - Disclosure - SHAREHOLDERS' EQUITY AND REGULATORY CAPITAL - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SHAREHOLDERSEQUITYANDREGULATORYCAPITALNarrativeDetails</Role>
      <ShortName>SHAREHOLDERS' EQUITY AND REGULATORY CAPITAL - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>9955568 - Disclosure - EARNINGS PER SHARE - Summary of Calculation of Basic and Diluted Earnings per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/EARNINGSPERSHARESummaryofCalculationofBasicandDilutedEarningsperShareDetails</Role>
      <ShortName>EARNINGS PER SHARE - Summary of Calculation of Basic and Diluted Earnings per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>9955569 - Disclosure - EARNINGS PER SHARE - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/EARNINGSPERSHARENarrativeDetails</Role>
      <ShortName>EARNINGS PER SHARE - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>9955570 - Disclosure - FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK - Summary of Contractual or Notional Amounts, Commitments to Fund (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FINANCIALINSTRUMENTSWITHOFFBALANCESHEETRISKSummaryofContractualorNotionalAmountsCommitmentstoFundDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK - Summary of Contractual or Notional Amounts, Commitments to Fund (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>9955571 - Disclosure - FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FINANCIALINSTRUMENTSWITHOFFBALANCESHEETRISKNarrativeDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/FINANCIALINSTRUMENTSWITHOFFBALANCESHEETRISKTables</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>9955572 - Disclosure - FAIR VALUE - Summary of Assets Measured at Fair Value on Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUESummaryofAssetsMeasuredatFairValueonRecurringBasisDetails</Role>
      <ShortName>FAIR VALUE - Summary of Assets Measured at Fair Value on Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>9955573 - Disclosure - FAIR VALUE - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUENarrativeDetails</Role>
      <ShortName>FAIR VALUE - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>9955574 - Disclosure - FAIR VALUE - Summary of Level 3 Fair Value Measurement Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUESummaryofLevel3FairValueMeasurementActivityDetails</Role>
      <ShortName>FAIR VALUE - Summary of Level 3 Fair Value Measurement Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>9955575 - Disclosure - FAIR VALUE - Summary of Assets Measured at Fair Value on Nonrecurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUESummaryofAssetsMeasuredatFairValueonNonrecurringBasisDetails</Role>
      <ShortName>FAIR VALUE - Summary of Assets Measured at Fair Value on Nonrecurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>9955576 - Disclosure - FAIR VALUE - Summary of Additional Qualitative Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUESummaryofAdditionalQualitativeInformationDetails</Role>
      <ShortName>FAIR VALUE - Summary of Additional Qualitative Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>9955577 - Disclosure - FAIR VALUE - Summary of Financial Instruments at Carrying Amounts and Estimated Fair Values (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/FAIRVALUESummaryofFinancialInstrumentsatCarryingAmountsandEstimatedFairValuesDetails</Role>
      <ShortName>FAIR VALUE - Summary of Financial Instruments at Carrying Amounts and Estimated Fair Values (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>9955578 - Disclosure - SEGMENT REPORTING (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/SEGMENTREPORTINGDetails</Role>
      <ShortName>SEGMENT REPORTING (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/SEGMENTREPORTING</ParentRole>
      <Position>94</Position>
    </Report>
    <Report instance="orrf-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>9955579 - Disclosure - CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.orrstown.com/role/CONTINGENCIESDetails</Role>
      <ShortName>CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.orrstown.com/role/CONTINGENCIES</ParentRole>
      <Position>95</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="orrf-20260331.htm">orrf-20260331.htm</File>
    <File>orrf-20260331.xsd</File>
    <File>orrf-20260331_cal.xml</File>
    <File>orrf-20260331_def.xml</File>
    <File>orrf-20260331_lab.xml</File>
    <File>orrf-20260331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="1">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="3226">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="29">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
