<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>140</ContextCount>
  <ElementCount>199</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>41</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover Page</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CoverPage</Role>
      <ShortName>Cover Page</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0000003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0000004 - Statement - Condensed Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedStatementsofOperations</Role>
      <ShortName>Condensed Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0000005 - Statement - Condensed Consolidated Statements of Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedStatementsofComprehensiveLoss</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive Loss</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0000006 - Statement - Condensed Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedStatementsofStockholdersEquity</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0000007 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedStatementsofCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0000008 - Statement - Condensed Consolidated Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CondensedConsolidatedStatementsofCashFlowsParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0000009 - Disclosure - Organization</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/Organization</Role>
      <ShortName>Organization</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0000010 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/SummaryofSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0000011 - Disclosure - Investment Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/InvestmentSecurities</Role>
      <ShortName>Investment Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0000012 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0000013 - Disclosure - Inventory</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/Inventory</Role>
      <ShortName>Inventory</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0000014 - Disclosure - Right of Use Assets and Lease Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/RightofUseAssetsandLeaseLiabilities</Role>
      <ShortName>Right of Use Assets and Lease Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0000015 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0000016 - Disclosure - Share-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/ShareBasedCompensation</Role>
      <ShortName>Share-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0000017 - Disclosure - Loss Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/LossPerShare</Role>
      <ShortName>Loss Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0000018 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/SummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>18</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0000019 - Disclosure - Investment Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/InvestmentSecuritiesTables</Role>
      <ShortName>Investment Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/InvestmentSecurities</ParentRole>
      <Position>19</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>0000020 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/FairValueMeasurements</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>0000021 - Disclosure - Inventory (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/InventoryTables</Role>
      <ShortName>Inventory (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/Inventory</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>0000022 - Disclosure - Right of Use Assets and Lease Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/RightofUseAssetsandLeaseLiabilitiesTables</Role>
      <ShortName>Right of Use Assets and Lease Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/RightofUseAssetsandLeaseLiabilities</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>0000023 - Disclosure - Share-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/ShareBasedCompensationTables</Role>
      <ShortName>Share-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/ShareBasedCompensation</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>0000024 - Disclosure - Loss Per Share - (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/LossPerShareTables</Role>
      <ShortName>Loss Per Share - (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.intracellulartherapies.com/role/LossPerShare</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>0000025 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/SummaryofSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>0000026 - Disclosure - Investment Securities - Summary of Investment Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/InvestmentSecuritiesSummaryofInvestmentSecuritiesDetail</Role>
      <ShortName>Investment Securities - Summary of Investment Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>0000027 - Disclosure - Investment Securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/InvestmentSecuritiesAdditionalInformationDetail</Role>
      <ShortName>Investment Securities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>0000028 - Disclosure - Fair Value Measurements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/FairValueMeasurementsAdditionalInformationDetail</Role>
      <ShortName>Fair Value Measurements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>0000029 - Disclosure - Fair Value Measurements - Schedule of Fair Value Measurements of Cash Equivalents (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/FairValueMeasurementsScheduleofFairValueMeasurementsofCashEquivalentsDetail</Role>
      <ShortName>Fair Value Measurements - Schedule of Fair Value Measurements of Cash Equivalents (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>0000030 - Disclosure - Inventory - Schedule of Inventory, Current (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/InventoryScheduleofInventoryCurrentDetail</Role>
      <ShortName>Inventory - Schedule of Inventory, Current (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>0000031 - Disclosure - Right of Use Assets and Lease Liabilities - Schedule Of Quantitative Information About Operating Leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/RightofUseAssetsandLeaseLiabilitiesScheduleOfQuantitativeInformationAboutOperatingLeasesDetail</Role>
      <ShortName>Right of Use Assets and Lease Liabilities - Schedule Of Quantitative Information About Operating Leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>0000032 - Disclosure - Right of Use Assets and Lease Liabilities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/RightofUseAssetsandLeaseLiabilitiesAdditionalInformationDetails</Role>
      <ShortName>Right of Use Assets and Lease Liabilities - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>0000033 - Disclosure - Right of Use Assets and Lease Liabilities - Maturity analysis under the lease agreements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/RightofUseAssetsandLeaseLiabilitiesMaturityanalysisundertheleaseagreementsDetail</Role>
      <ShortName>Right of Use Assets and Lease Liabilities - Maturity analysis under the lease agreements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>0000034 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/CommitmentsandContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>0000035 - Disclosure - Share-Based Compensation - Total Stock-Based Compensation Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/ShareBasedCompensationTotalStockBasedCompensationExpenseDetail</Role>
      <ShortName>Share-Based Compensation - Total Stock-Based Compensation Expense (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>0000036 - Disclosure - Share-Based Compensation - Stock Options Activity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/ShareBasedCompensationStockOptionsActivityDetail</Role>
      <ShortName>Share-Based Compensation - Stock Options Activity (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>0000037 - Disclosure - Share-Based Compensation - Summary of Information Regarding the Time Based RSU Activity and Changes (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/ShareBasedCompensationSummaryofInformationRegardingtheTimeBasedRSUActivityandChangesDetail</Role>
      <ShortName>Share-Based Compensation - Summary of Information Regarding the Time Based RSU Activity and Changes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>0000038 - Disclosure - Share-Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/ShareBasedCompensationAdditionalInformationDetail</Role>
      <ShortName>Share-Based Compensation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="itci-20230331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>0000039 - Disclosure - Loss Per Share - Common Stock Equivalents Excluded in Calculation of Diluted Loss Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.intracellulartherapies.com/role/LossPerShareCommonStockEquivalentsExcludedinCalculationofDilutedLossPerShareDetail</Role>
      <ShortName>Loss Per Share - Common Stock Equivalents Excluded in Calculation of Diluted Loss Per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</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="itci-20230331.htm">itci-20230331.htm</File>
    <File>itci-20230331.xsd</File>
    <File>itci-20230331_cal.xml</File>
    <File>itci-20230331_def.xml</File>
    <File>itci-20230331_lab.xml</File>
    <File>itci-20230331_pre.xml</File>
    <File>itci-20230331xex102.htm</File>
    <File>itci-20230331xex311.htm</File>
    <File>itci-20230331xex312.htm</File>
    <File>itci-20230331xex32.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="434">http://fasb.org/us-gaap/2022</BaseTaxonomy>
    <BaseTaxonomy items="29">http://xbrl.sec.gov/dei/2022</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
