<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.21.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>386</ContextCount>
  <ElementCount>482</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>72</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001002 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITION</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002003 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITIONParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003004 - Statement - CONSOLIDATED STATEMENTS OF INCOME (LOSS)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFINCOMELOSS</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF INCOME (LOSS)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1004005 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1005006 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSSParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1006007 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1007008 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITYParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>1008009 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2101101 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/BasisofPresentation</Role>
      <ShortName>Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2103102 - Disclosure - Business Combinations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/BusinessCombinations</Role>
      <ShortName>Business Combinations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2107103 - Disclosure - Earnings (Loss) per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/EarningsLossperShare</Role>
      <ShortName>Earnings (Loss) per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2111104 - Disclosure - Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/Securities</Role>
      <ShortName>Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2121105 - Disclosure - Loans Receivable, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNet</Role>
      <ShortName>Loans Receivable, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2130106 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/Deposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2134107 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2139108 - Disclosure - Derivatives, Hedging Activities, and Other Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DerivativesHedgingActivitiesandOtherFinancialInstruments</Role>
      <ShortName>Derivatives, Hedging Activities, and Other Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2143109 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2150110 - Disclosure - Subsequent Event</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SubsequentEvent</Role>
      <ShortName>Subsequent Event</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2202201 - Disclosure - Basis of Presentation (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/BasisofPresentationPolicies</Role>
      <ShortName>Basis of Presentation (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2304301 - Disclosure - Business Combinations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/BusinessCombinationsTables</Role>
      <ShortName>Business Combinations (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/BusinessCombinations</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2308302 - Disclosure - Earnings (Loss) per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/EarningsLossperShareTables</Role>
      <ShortName>Earnings (Loss) per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/EarningsLossperShare</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2312303 - Disclosure - Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesTables</Role>
      <ShortName>Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/Securities</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2322304 - Disclosure - Loans Receivable, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetTables</Role>
      <ShortName>Loans Receivable, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/LoansReceivableNet</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2331305 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/Deposits</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2335306 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/FairValueMeasurements</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2340307 - Disclosure - Derivatives, Hedging Activities, and Other Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DerivativesHedgingActivitiesandOtherFinancialInstrumentsTables</Role>
      <ShortName>Derivatives, Hedging Activities, and Other Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/DerivativesHedgingActivitiesandOtherFinancialInstruments</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2344308 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/Leases</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2405401 - Disclosure - Business Combinations - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/BusinessCombinationsAdditionalInformationDetails</Role>
      <ShortName>Business Combinations - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - Business Combinations - Summary of Assets Acquired and Liabilities Assumed and Their Initial Fair Value Estimates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/BusinessCombinationsSummaryofAssetsAcquiredandLiabilitiesAssumedandTheirInitialFairValueEstimatesDetails</Role>
      <ShortName>Business Combinations - Summary of Assets Acquired and Liabilities Assumed and Their Initial Fair Value Estimates (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - Earnings (Loss) per Share - Reconciliation of Shares Outstanding for Basic and Diluted Earnings per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/EarningsLossperShareReconciliationofSharesOutstandingforBasicandDilutedEarningsperShareDetails</Role>
      <ShortName>Earnings (Loss) per Share - Reconciliation of Shares Outstanding for Basic and Diluted Earnings per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/EarningsLossperShareTables</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2410404 - Disclosure - Earnings (Loss) per Share - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/EarningsLossperShareAdditionalInformationDetails</Role>
      <ShortName>Earnings (Loss) per Share - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.oceanfirstonline.com/role/EarningsLossperShareTables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2413405 - Disclosure - Securities - Amortized Cost and Estimated Fair Value of Securities Available-for-Sale and Held-to-Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesAmortizedCostandEstimatedFairValueofSecuritiesAvailableforSaleandHeldtoMaturityDetails</Role>
      <ShortName>Securities - Amortized Cost and Estimated Fair Value of Securities Available-for-Sale and Held-to-Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2414406 - Disclosure - Securities - Allowance for Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesAllowanceforCreditLossesDetails</Role>
      <ShortName>Securities - Allowance for Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2415407 - Disclosure - Securities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesAdditionalInformationDetails</Role>
      <ShortName>Securities - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2416408 - Disclosure - Securities - Carrying Value of Held-to-Maturity Investment Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesCarryingValueofHeldtoMaturityInvestmentSecuritiesDetails</Role>
      <ShortName>Securities - Carrying Value of Held-to-Maturity Investment Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2417409 - Disclosure - Securities - Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesAmortizedCostandEstimatedFairValueofInvestmentSecuritiesbyContractualMaturityDetails</Role>
      <ShortName>Securities - Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2418410 - Disclosure - Securities - Estimated Fair Value and Unrealized Loss for Securities Available-for-Sale and Held-to-Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesEstimatedFairValueandUnrealizedLossforSecuritiesAvailableforSaleandHeldtoMaturityDetails</Role>
      <ShortName>Securities - Estimated Fair Value and Unrealized Loss for Securities Available-for-Sale and Held-to-Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2419411 - Disclosure - Securities - Credit Quality Indicator (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesCreditQualityIndicatorDetails</Role>
      <ShortName>Securities - Credit Quality Indicator (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2420412 - Disclosure - Securities - Equity Securities Realized Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/SecuritiesEquitySecuritiesRealizedLossesDetails</Role>
      <ShortName>Securities - Equity Securities Realized Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2423413 - Disclosure - Loans Receivable, Net - Components of Loans Receivable, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetComponentsofLoansReceivableNetDetails</Role>
      <ShortName>Loans Receivable, Net - Components of Loans Receivable, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2424414 - Disclosure - Loans Receivable, Net - Credit Grades and Risk Characteristics (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetCreditGradesandRiskCharacteristicsDetails</Role>
      <ShortName>Loans Receivable, Net - Credit Grades and Risk Characteristics (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2425415 - Disclosure - Loans Receivable, Net - Allowance for Loan Losses and Recorded Investment in Loans by Portfolio Segment and Based on Impairment Method Excluding PCI Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetAllowanceforLoanLossesandRecordedInvestmentinLoansbyPortfolioSegmentandBasedonImpairmentMethodExcludingPCILoansDetails</Role>
      <ShortName>Loans Receivable, Net - Allowance for Loan Losses and Recorded Investment in Loans by Portfolio Segment and Based on Impairment Method Excluding PCI Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2426416 - Disclosure - Loans Receivable, Net - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetAdditionalInformationDetails</Role>
      <ShortName>Loans Receivable, Net - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2427417 - Disclosure - Loans Receivable, Net - Recorded Investment in Non-Accrual Loans by Loan Portfolio Segment Excluding PCI Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetRecordedInvestmentinNonAccrualLoansbyLoanPortfolioSegmentExcludingPCILoansDetails</Role>
      <ShortName>Loans Receivable, Net - Recorded Investment in Non-Accrual Loans by Loan Portfolio Segment Excluding PCI Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2428418 - Disclosure - Loans Receivable, Net - Aging of Recorded Investment in Past Due Loans Excluding PCI Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetAgingofRecordedInvestmentinPastDueLoansExcludingPCILoansDetails</Role>
      <ShortName>Loans Receivable, Net - Aging of Recorded Investment in Past Due Loans Excluding PCI Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2429419 - Disclosure - Loans Receivable, Net - Troubled Debt Restructurings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LoansReceivableNetTroubledDebtRestructuringsDetails</Role>
      <ShortName>Loans Receivable, Net - Troubled Debt Restructurings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2432420 - Disclosure - Deposits - Summary of Major Types of Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DepositsSummaryofMajorTypesofDepositsDetails</Role>
      <ShortName>Deposits - Summary of Major Types of Deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2433421 - Disclosure - Deposits - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DepositsAdditionalInformationDetails</Role>
      <ShortName>Deposits - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2436422 - Disclosure - Fair Value Measurements - Financial Assets and Financial Liabilities Measured at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/FairValueMeasurementsFinancialAssetsandFinancialLiabilitiesMeasuredatFairValueDetails</Role>
      <ShortName>Fair Value Measurements - Financial Assets and Financial Liabilities Measured at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2437423 - Disclosure - Fair Value Measurements - Debt Securities Available for Sale Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/FairValueMeasurementsDebtSecuritiesAvailableforSaleReconciliationDetails</Role>
      <ShortName>Fair Value Measurements - Debt Securities Available for Sale Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2438424 - Disclosure - Fair Value Measurements - Book Value and Estimated Fair Value of Bank's Significant Financial Instruments Not Recorded at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/FairValueMeasurementsBookValueandEstimatedFairValueofBanksSignificantFinancialInstrumentsNotRecordedatFairValueDetails</Role>
      <ShortName>Fair Value Measurements - Book Value and Estimated Fair Value of Bank's Significant Financial Instruments Not Recorded at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2441425 - Disclosure - Derivatives, Hedging Activities, and Other Financial Instruments - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DerivativesHedgingActivitiesandOtherFinancialInstrumentsAdditionalInformationDetails</Role>
      <ShortName>Derivatives, Hedging Activities, and Other Financial Instruments - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2442426 - Disclosure - Derivatives, Hedging Activities, and Other Financial Instruments - Notional and Fair Value of Derivatives Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/DerivativesHedgingActivitiesandOtherFinancialInstrumentsNotionalandFairValueofDerivativesAssetsandLiabilitiesDetails</Role>
      <ShortName>Derivatives, Hedging Activities, and Other Financial Instruments - Notional and Fair Value of Derivatives Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2445427 - Disclosure - Leases - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LeasesNarrativeDetails</Role>
      <ShortName>Leases - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2446428 - Disclosure - Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LeasesScheduleofRightofUseAssetsandLeaseLiabilitiesDetails</Role>
      <ShortName>Leases - Schedule of Right-of-Use Assets and Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2447429 - Disclosure - Leases - Schedule of Weighted Average Remaining Lease Term and Discount Rate (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LeasesScheduleofWeightedAverageRemainingLeaseTermandDiscountRateDetails</Role>
      <ShortName>Leases - Schedule of Weighted Average Remaining Lease Term and Discount Rate (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2448430 - Disclosure - Leases - Schedule of Lease Costs and Other Lease Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LeasesScheduleofLeaseCostsandOtherLeaseInformationDetails</Role>
      <ShortName>Leases - Schedule of Lease Costs and Other Lease Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2449431 - Disclosure - Leases - Future Minimum Payments for Operating and Financing Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.oceanfirstonline.com/role/LeasesFutureMinimumPaymentsforOperatingandFinancingLeasesDetails</Role>
      <ShortName>Leases - Future Minimum Payments for Operating and Financing Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ocfc-20210930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9999.htm</HtmlFileName>
      <LongName>Uncategorized Items - ocfc-20210930.htm</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/role/uncategorizedFacts</Role>
      <ShortName>Uncategorized Items - ocfc-20210930.htm</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>60</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" original="ocfc-20210930.htm">ocfc-20210930.htm</File>
    <File>exhibit1012021q3.htm</File>
    <File>exhibit1022021q3.htm</File>
    <File>exhibit311q321.htm</File>
    <File>exhibit312q321.htm</File>
    <File>exhibit320q321.htm</File>
    <File>ocfc-20210930.xsd</File>
    <File>ocfc-20210930_cal.xml</File>
    <File>ocfc-20210930_def.xml</File>
    <File>ocfc-20210930_lab.xml</File>
    <File>ocfc-20210930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2021</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2021-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
