<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.10.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>315</ContextCount>
  <ElementCount>449</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>98</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000100 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>010000 - Statement - CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ConsolidatedStatementsOfIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>020000 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>030000 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>030100 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>040000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>050000 - Statement - CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDER'S EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ConsolidatedStatementOfChangesInStockholderSEquity</Role>
      <ShortName>CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDER'S EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>060100 - Disclosure - BACKGROUND AND BASIS OF PRESENTATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/BackgroundAndBasisOfPresentation</Role>
      <ShortName>BACKGROUND AND BASIS OF PRESENTATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>060200 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SummaryOfSignificantAccountingPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>060300 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FairValueOfFinancialInstruments</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>060400 - Disclosure - INVENTORIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/Inventories</Role>
      <ShortName>INVENTORIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>060500 - Disclosure - PROPERTY, PLANT AND EQUIPMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/PropertyPlantAndEquipment</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>060600 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/GoodwillAndOtherIntangibleAssets</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>060700 - Disclosure - OTHER LONG-TERM ASSETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/OtherLongtermAssets</Role>
      <ShortName>OTHER LONG-TERM ASSETS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>060800 - Disclosure - ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/AccruedExpensesIncomeTaxesPayableAndOtherCurrentLiabilities</Role>
      <ShortName>ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>060900 - Disclosure - DEBT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/Debt</Role>
      <ShortName>DEBT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>061000 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS, Cash Flow Hedges, Foreign Currency Contracts, and Net Investment Contracts</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DerivativeFinancialInstrumentsCashFlowHedgesForeignCurrencyContractsAndNetInvestmentContracts</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS, Cash Flow Hedges, Foreign Currency Contracts, and Net Investment Contracts</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>061100 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/AccumulatedOtherComprehensiveIncome</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>061200 - Disclosure - SHARE-BASED COMPENSATION PLANS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlans</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>061300 - Disclosure - SAVINGS PLAN</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SavingsPlan</Role>
      <ShortName>SAVINGS PLAN</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>061400 - Disclosure - OTHER INCOME, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/OtherIncomeNet</Role>
      <ShortName>OTHER INCOME, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>061500 - Disclosure - STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/StockholdersEquity</Role>
      <ShortName>STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>061600 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxes</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>061700 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/CommitmentsAndContingencies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>061800 - Disclosure - EARNINGS PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/EarningsPerShare</Role>
      <ShortName>EARNINGS PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>061900 - Disclosure - FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FinancialInformationByIndustrySegmentGeographicAreaAndProductLine</Role>
      <ShortName>FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>062000 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SubsequentEvents</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>062100 - Disclosure - SELECTED QUARTERLY OPERATING RESULTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SelectedQuarterlyOperatingResults</Role>
      <ShortName>SELECTED QUARTERLY OPERATING RESULTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>062200 - Schedule - SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ScheduleIiValuationAndQualifyingAccounts</Role>
      <ShortName>SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>070200 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>080200 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>080300 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FairValueOfFinancialInstrumentsTables</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>080400 - Disclosure - INVENTORIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/InventoriesTables</Role>
      <ShortName>INVENTORIES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>080500 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/PropertyPlantAndEquipmentTables</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>080600 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/GoodwillAndOtherIntangibleAssetsTables</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>080700 - Disclosure - OTHER LONG-TERM ASSETS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/OtherLongtermAssetsTables</Role>
      <ShortName>OTHER LONG-TERM ASSETS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>080800 - Disclosure - ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/AccruedExpensesIncomeTaxesPayableAndOtherCurrentLiabilitiesTables</Role>
      <ShortName>ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>081000 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS, Cash Flow Hedges, Foreign Currency Contracts, and Net Investment Contracts (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DerivativeFinancialInstrumentsCashFlowHedgesForeignCurrencyContractsAndNetInvestmentContractsTables</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS, Cash Flow Hedges, Foreign Currency Contracts, and Net Investment Contracts (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>081100 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/AccumulatedOtherComprehensiveIncomeTables</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>081200 - Disclosure - SHARE-BASED COMPENSATION PLANS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlansTables</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>081400 - Disclosure - OTHER INCOME, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/OtherIncomeNetTables</Role>
      <ShortName>OTHER INCOME, NET (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>081500 - Disclosure - STOCKHOLDERS' EQUITY (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/StockholdersEquityTables</Role>
      <ShortName>STOCKHOLDERS' EQUITY (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>081600 - Disclosure - INCOME TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesTables</Role>
      <ShortName>INCOME TAXES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>081700 - Disclosure - COMMITMENTS AND CONTINGENCIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/CommitmentsAndContingenciesTables</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>081800 - Disclosure - EARNINGS PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/EarningsPerShareTables</Role>
      <ShortName>EARNINGS PER SHARE (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>081900 - Disclosure - FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FinancialInformationByIndustrySegmentGeographicAreaAndProductLineTables</Role>
      <ShortName>FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>082100 - Disclosure - SELECTED QUARTERLY OPERATING RESULTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SelectedQuarterlyOperatingResultsTables</Role>
      <ShortName>SELECTED QUARTERLY OPERATING RESULTS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>090100 - Disclosure - BACKGROUND AND BASIS OF PRESENTATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/BackgroundAndBasisOfPresentationDetails</Role>
      <ShortName>BACKGROUND AND BASIS OF PRESENTATION (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>090200 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>090300 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>090400 - Disclosure - INVENTORIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/InventoriesDetails</Role>
      <ShortName>INVENTORIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>090500 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/PropertyPlantAndEquipmentDetails</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>090600 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/GoodwillAndOtherIntangibleAssetsDetails</Role>
      <ShortName>GOODWILL AND OTHER INTANGIBLE ASSETS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>090700 - Disclosure - OTHER LONG-TERM ASSETS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/OtherLongtermAssetsDetails</Role>
      <ShortName>OTHER LONG-TERM ASSETS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>090800 - Disclosure - ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/AccruedExpensesIncomeTaxesPayableAndOtherCurrentLiabilitiesDetails</Role>
      <ShortName>ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>090900 - Disclosure - DEBT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DebtDetails</Role>
      <ShortName>DEBT (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>091000 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS, Cash Flow Hedges, Foreign Currency Contracts, and Net Investment Contracts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DerivativeFinancialInstrumentsCashFlowHedgesForeignCurrencyContractsAndNetInvestmentContractsDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS, Cash Flow Hedges, Foreign Currency Contracts, and Net Investment Contracts (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>091002 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS, Net Investment Hedges in Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DerivativeFinancialInstrumentsNetInvestmentHedgesInAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS, Net Investment Hedges in Accumulated Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>091004 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS, Fair Value of Derivative Instruments in the Consolidated Balance Sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DerivativeFinancialInstrumentsFairValueOfDerivativeInstrumentsInConsolidatedBalanceSheetDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS, Fair Value of Derivative Instruments in the Consolidated Balance Sheet (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>091006 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS, Effect of Derivative Instruments on the Consolidated Statement of Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/DerivativeFinancialInstrumentsEffectOfDerivativeInstrumentsOnConsolidatedStatementOfIncomeDetails</Role>
      <ShortName>DERIVATIVE FINANCIAL INSTRUMENTS, Effect of Derivative Instruments on the Consolidated Statement of Income (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>091100 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/AccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>091200 - Disclosure - SHARE-BASED COMPENSATION PLANS, Equity and Omnibus Incentive Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlansEquityAndOmnibusIncentivePlansDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS, Equity and Omnibus Incentive Plans (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>091202 - Disclosure - SHARE-BASED COMPENSATION PLANS, Weighted Average Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlansWeightedAverageAssumptionsDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS, Weighted Average Assumptions (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>091204 - Disclosure - SHARE-BASED COMPENSATION PLANS, Share-Based Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlansSharebasedCompensationExpenseDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS, Share-Based Compensation Expense (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>091206 - Disclosure - SHARE-BASED COMPENSATION PLANS, Stock Option Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlansStockOptionActivityDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS, Stock Option Activity (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>091208 - Disclosure - SHARE-BASED COMPENSATION PLANS, Restricted Stock and Restricted Stock Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SharebasedCompensationPlansRestrictedStockAndRestrictedStockUnitsDetails</Role>
      <ShortName>SHARE-BASED COMPENSATION PLANS, Restricted Stock and Restricted Stock Units (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>091300 - Disclosure - SAVINGS PLAN (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SavingsPlanDetails</Role>
      <ShortName>SAVINGS PLAN (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>091400 - Disclosure - OTHER INCOME, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/OtherIncomeNetDetails</Role>
      <ShortName>OTHER INCOME, NET (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>091500 - Disclosure - STOCKHOLDERS' EQUITY (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/StockholdersEquityDetails</Role>
      <ShortName>STOCKHOLDERS' EQUITY (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>091600 - Disclosure - INCOME TAXES, Income Before Income Taxes and Taxes on Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesIncomeBeforeIncomeTaxesAndTaxesOnIncomeDetails</Role>
      <ShortName>INCOME TAXES, Income Before Income Taxes and Taxes on Income (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>091602 - Disclosure - INCOME TAXES, Provision for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesProvisionForIncomeTaxesDetails</Role>
      <ShortName>INCOME TAXES, Provision for Income Taxes (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>091604 - Disclosure - INCOME TAXES, Tax Act and Tax Impact of Foreign Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesTaxActAndTaxImpactOfForeignOperationsDetails</Role>
      <ShortName>INCOME TAXES, Tax Act and Tax Impact of Foreign Operations (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>091606 - Disclosure - INCOME TAXES, Changes in the Gross Unrecognized Tax benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesChangesInGrossUnrecognizedTaxBenefitsDetails</Role>
      <ShortName>INCOME TAXES, Changes in the Gross Unrecognized Tax benefits (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>091608 - Disclosure - INCOME TAXES, Components of Net Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesComponentsOfNetDeferredTaxAssetsAndLiabilitiesDetails</Role>
      <ShortName>INCOME TAXES, Components of Net Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>091610 - Disclosure - INCOME TAXES, Net Operating Loss, Capital, and Tax Credit Carryforwards (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/IncomeTaxesNetOperatingLossCapitalAndTaxCreditCarryforwardsDetails</Role>
      <ShortName>INCOME TAXES, Net Operating Loss, Capital, and Tax Credit Carryforwards (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>091700 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/CommitmentsAndContingenciesDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>091800 - Disclosure - EARNINGS PER SHARE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/EarningsPerShareDetails</Role>
      <ShortName>EARNINGS PER SHARE (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>091900 - Disclosure - FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Financial Information by Geographic Area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FinancialInformationByIndustrySegmentGeographicAreaAndProductLineFinancialInformationByGeographicAreaDetails</Role>
      <ShortName>FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Financial Information by Geographic Area (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>091902 - Disclosure - FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Revenue by Major Foreign Customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FinancialInformationByIndustrySegmentGeographicAreaAndProductLineRevenueByMajorForeignCustomersDetails</Role>
      <ShortName>FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Revenue by Major Foreign Customers (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>091904 - Disclosure - FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Long-Lived Assets by Major Customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FinancialInformationByIndustrySegmentGeographicAreaAndProductLineLonglivedAssetsByMajorCustomersDetails</Role>
      <ShortName>FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Long-Lived Assets by Major Customers (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>091906 - Disclosure - FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Revenue Generated by Product Area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/FinancialInformationByIndustrySegmentGeographicAreaAndProductLineRevenueGeneratedByProductAreaDetails</Role>
      <ShortName>FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, Revenue Generated by Product Area (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>092000 - Disclosure - SUBSEQUENT EVENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SubsequentEventsDetails</Role>
      <ShortName>SUBSEQUENT EVENTS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>092100 - Disclosure - SELECTED QUARTERLY OPERATING RESULTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/SelectedQuarterlyOperatingResultsDetails</Role>
      <ShortName>SELECTED QUARTERLY OPERATING RESULTS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="ccmp-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>092200 - Schedule - SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://cabotcmp.com/role/ScheduleIiValuationAndQualifyingAccountsDetails</Role>
      <ShortName>SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ccmp-20180930.xml</File>
    <File>ccmp-20180930.xsd</File>
    <File>ccmp-20180930_cal.xml</File>
    <File>ccmp-20180930_def.xml</File>
    <File>ccmp-20180930_lab.xml</File>
    <File>ccmp-20180930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/srt/2018-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2018-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2018-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/invest/2013-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
