<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.2.0.727</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>187</ContextCount>
  <ElementCount>318</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>66</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>9</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/StatementCONDENSEDCONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/StatementCONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSSUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTOFCHANGESINSTOCKHOLDERSEQUITYUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Disclosure - BUSINESS AND NATURE OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureBUSINESSANDNATUREOFOPERATIONS</Role>
      <ShortName>BUSINESS AND NATURE OF OPERATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Disclosure - BASIS OF PRESENTATION AND MANAGEMENT PLANS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureBASISOFPRESENTATIONANDMANAGEMENTPLANS</Role>
      <ShortName>BASIS OF PRESENTATION AND MANAGEMENT PLANS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSIGNIFICANTACCOUNTINGPOLICIES</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - FAIR VALUE MEASUREMENTS AND INVESTMENTS IN MARKETABLE SECURITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureFAIRVALUEMEASUREMENTSANDINVESTMENTSINMARKETABLESECURITIES</Role>
      <ShortName>FAIR VALUE MEASUREMENTS AND INVESTMENTS IN MARKETABLE SECURITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - PROPERTY AND EQUIPMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosurePROPERTYANDEQUIPMENT</Role>
      <ShortName>PROPERTY AND EQUIPMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - LICENSE AND COLLABORATION AGREEMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureLICENSEANDCOLLABORATIONAGREEMENTS</Role>
      <ShortName>LICENSE AND COLLABORATION AGREEMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - CONVERTIBLE NOTES PAYABLE</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureCONVERTIBLENOTESPAYABLE</Role>
      <ShortName>CONVERTIBLE NOTES PAYABLE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSTOCKHOLDERSEQUITY</Role>
      <ShortName>STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - STOCK BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSTOCKBASEDCOMPENSATION</Role>
      <ShortName>STOCK BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureINCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - RELATED PARTIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureRELATEDPARTIES</Role>
      <ShortName>RELATED PARTIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureCOMMITMENTSANDCONTINGENCIES</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - T-CELL FACTORY ACQUISITION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCELLFACTORYACQUISITION</Role>
      <ShortName>T-CELL FACTORY ACQUISITION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSIGNIFICANTACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSIGNIFICANTACCOUNTINGPOLICIESTables</Role>
      <ShortName>SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSIGNIFICANTACCOUNTINGPOLICIES</ParentRole>
      <Position>21</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - FAIR VALUE MEASUREMENTS AND INVESTMENTS IN MARKETABLE SECURITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureFAIRVALUEMEASUREMENTSANDINVESTMENTSINMARKETABLESECURITIESTables</Role>
      <ShortName>FAIR VALUE MEASUREMENTS AND INVESTMENTS IN MARKETABLE SECURITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureFAIRVALUEMEASUREMENTSANDINVESTMENTSINMARKETABLESECURITIES</ParentRole>
      <Position>22</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - PROPERTY AND EQUIPMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosurePROPERTYANDEQUIPMENTTables</Role>
      <ShortName>PROPERTY AND EQUIPMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kitepharma.com/20150630/taxonomy/role/DisclosurePROPERTYANDEQUIPMENT</ParentRole>
      <Position>23</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - STOCK BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSTOCKBASEDCOMPENSATIONTables</Role>
      <ShortName>STOCK BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSTOCKBASEDCOMPENSATION</ParentRole>
      <Position>24</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - T-CELL FACTORY ACQUISITION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCELLFACTORYACQUISITIONTables</Role>
      <ShortName>T-CELL FACTORY ACQUISITION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCELLFACTORYACQUISITION</ParentRole>
      <Position>25</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Business and Nature of Operations - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureBusinessAndNatureOfOperationsAdditionalInformationDetails</Role>
      <ShortName>Business and Nature of Operations - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Basis of Presentation and Management Plans - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureBasisOfPresentationAndManagementPlansAdditionalInformationDetails</Role>
      <ShortName>Basis of Presentation and Management Plans - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Significant Accounting Policies - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSignificantAccountingPoliciesAdditionalInformationDetails</Role>
      <ShortName>Significant Accounting Policies - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Significant Accounting Policies - Summary of Accrued Expenses and Other Current Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSignificantAccountingPoliciesSummaryOfAccruedExpensesAndOtherCurrentLiabilitiesDetail</Role>
      <ShortName>Significant Accounting Policies - Summary of Accrued Expenses and Other Current Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Significant Accounting Policies - Summary of Potentially Dilutive Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSignificantAccountingPoliciesSummaryOfPotentiallyDilutiveSecuritiesDetail</Role>
      <ShortName>Significant Accounting Policies - Summary of Potentially Dilutive Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Significant Accounting Policies - Summary of Securities Excluded from the Computation of Potentially Dilutive Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSignificantAccountingPoliciesSummaryOfSecuritiesExcludedFromComputationOfPotentiallyDilutiveSecuritiesDetail</Role>
      <ShortName>Significant Accounting Policies - Summary of Securities Excluded from the Computation of Potentially Dilutive Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Significant Accounting Policies - Schedule of Summary of Calculation of Basic and Diluted Net Loss Per Common Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureSignificantAccountingPoliciesScheduleOfSummaryOfCalculationOfBasicAndDilutedNetLossPerCommonShareDetail</Role>
      <ShortName>Significant Accounting Policies - Schedule of Summary of Calculation of Basic and Diluted Net Loss Per Common Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Fair Value Measurements and Investments in Marketable Securities - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureFairValueMeasurementsAndInvestmentsInMarketableSecuritiesSummaryOfAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetail</Role>
      <ShortName>Fair Value Measurements and Investments in Marketable Securities - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Fair Value Measurements and Investments in Marketable Securities - Available-for-sale Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureFairValueMeasurementsAndInvestmentsInMarketableSecuritiesAvailableForSaleSecuritiesDetail</Role>
      <ShortName>Fair Value Measurements and Investments in Marketable Securities - Available-for-sale Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Fair Value Measurements and Investments in Marketable Securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureFairValueMeasurementsAndInvestmentsInMarketableSecuritiesAdditionalInformationDetail</Role>
      <ShortName>Fair Value Measurements and Investments in Marketable Securities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Property and Equipment - Summary of Property and Equipment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosurePropertyAndEquipmentSummaryOfPropertyAndEquipmentDetail</Role>
      <ShortName>Property and Equipment - Summary of Property and Equipment (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Property and Equipment - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosurePropertyAndEquipmentAdditionalInformationDetail</Role>
      <ShortName>Property and Equipment - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100370 - Disclosure - License and Collaboration Agreements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail</Role>
      <ShortName>License and Collaboration Agreements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Convertible Notes Payable - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureConvertibleNotesPayableAdditionalInformationDetail</Role>
      <ShortName>Convertible Notes Payable - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Stockholders' Equity - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetail</Role>
      <ShortName>Stockholders' Equity - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Stock Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail</Role>
      <ShortName>Stock Based Compensation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Stock Based Compensation - Summary of Options Issued Under the Plan (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureStockBasedCompensationSummaryOfOptionsIssuedUnderPlanDetail</Role>
      <ShortName>Stock Based Compensation - Summary of Options Issued Under the Plan (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Stock Based Compensation - Schedule of Black-Scholes Option Pricing Model (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureStockBasedCompensationScheduleOfBlackScholesOptionPricingModelDetail</Role>
      <ShortName>Stock Based Compensation - Schedule of Black-Scholes Option Pricing Model (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Stock Based Compensation - Summary of Stock Based Compensation (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockBasedCompensationDetail</Role>
      <ShortName>Stock Based Compensation - Summary of Stock Based Compensation (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Stock Based Compensation- Schedule of Stock Options Outstanding (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureStockBasedCompensationScheduleOfStockOptionsOutstandingDetail</Role>
      <ShortName>Stock Based Compensation- Schedule of Stock Options Outstanding (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Related Parties - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureRelatedPartiesAdditionalInformationDetail</Role>
      <ShortName>Related Parties - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100480 - Disclosure - T-Cell Factory Acquisition - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCellFactoryAcquisitionAdditionalInformationDetails</Role>
      <ShortName>T-Cell Factory Acquisition - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100490 - Disclosure - T-Cell Factory Acquisition - Schedule of Calculation of Purchase Price (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCellFactoryAcquisitionScheduleOfCalculationOfPurchasePriceDetails</Role>
      <ShortName>T-Cell Factory Acquisition - Schedule of Calculation of Purchase Price (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100500 - Disclosure - T-Cell Factory Acquisition - Summary of Fair Value of Tangible and Intangible Assets Acquired and Liabilities Assumed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCellFactoryAcquisitionSummaryOfFairValueOfTangibleAndIntangibleAssetsAcquiredAndLiabilitiesAssumedDetails</Role>
      <ShortName>T-Cell Factory Acquisition - Summary of Fair Value of Tangible and Intangible Assets Acquired and Liabilities Assumed (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100510 - Disclosure - T-Cell Factory Acquisition - Summary of Amortizable Intangible Assets Acquired With Respective Amortization Periods (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kitepharma.com/20150630/taxonomy/role/DisclosureTCellFactoryAcquisitionSummaryOfAmortizableIntangibleAssetsAcquiredWithRespectiveAmortizationPeriodsDetails</Role>
      <ShortName>T-Cell Factory Acquisition - Summary of Amortizable Intangible Assets Acquired With Respective Amortization Periods (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9999.htm</HtmlFileName>
      <LongName>Uncategorized Items - kite-20150630.xml</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/role/uncategorizedFacts</Role>
      <ShortName>Uncategorized Items - kite-20150630.xml</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">In ''CONDENSED CONSOLIDATED BALANCE SHEETS'', column(s) 2, 4, 5 are contained in other reports, so were removed by flow through suppression.</Log>
    <Log type="Info">In ''CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)'', column(s) 1, 2 are contained in other reports, so were removed by flow through suppression.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value 420848000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value 42000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value 420848000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value -297000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:SharesOutstanding with value 41855304 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:SharesOutstanding with value 41855304 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value -58004000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value -297000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value 42000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2015-01-01. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited)'', fact us-gaap:StockholdersEquity with value -58004000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2015-01-01. Change the preferred label role or add facts.</Log>
  </Logs>
  <InputFiles>
    <File>kite-20150630.xml</File>
    <File>kite-20150630_cal.xml</File>
    <File>kite-20150630_def.xml</File>
    <File>kite-20150630_lab.xml</File>
    <File>kite-20150630_pre.xml</File>
    <File>kite-20150630.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>

