<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>232</ContextCount>
  <ElementCount>285</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>85</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000110 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>000111 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>000120 - Statement - Consolidated Statements of Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedStatementsOfComprehensiveIncomeLoss</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>000130 - Statement - Consolidated Statement of Stockholders' Equity and Mezzanine Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedStatementOfStockholdersEquityAndMezzanineEquity</Role>
      <ShortName>Consolidated Statement of Stockholders' Equity and Mezzanine Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>000131 - Statement - Consolidated Statement of Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedStatementOfStockholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statement of Stockholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>000140 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>000141 - Statement - Consolidated Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/StatementConsolidatedStatementsOfCashFlowsParenthetical</Role>
      <ShortName>Consolidated Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100100 - Disclosure - OVERVIEW AND BASIS OF PRESENTATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentation</Role>
      <ShortName>OVERVIEW AND BASIS OF PRESENTATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100200 - Disclosure - ACQUISITIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAcquisitions</Role>
      <ShortName>ACQUISITIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100300 - Disclosure - SEGMENT INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureSegmentInformation</Role>
      <ShortName>SEGMENT INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100401 - Disclosure - SIGNIFICANT CLIENTS AND OTHER CONCENTRATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureSignificantClientsAndOtherConcentrations</Role>
      <ShortName>SIGNIFICANT CLIENTS AND OTHER CONCENTRATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100500 - Disclosure - GOODWILL</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureGoodwill</Role>
      <ShortName>GOODWILL</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100600 - Disclosure - DERIVATIVES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivatives</Role>
      <ShortName>DERIVATIVES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100700 - Disclosure - FAIR VALUE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureFairValue</Role>
      <ShortName>FAIR VALUE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100800 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100900 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>101000 - Disclosure - DEFERRED REVENUE AND REMAINING PERFORMANCE OBLIGATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDeferredRevenueAndRemainingPerformanceObligations</Role>
      <ShortName>DEFERRED REVENUE AND REMAINING PERFORMANCE OBLIGATIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>101100 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLoss</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>101200 - Disclosure - WEIGHTED AVERAGE SHARE COUNTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureWeightedAverageShareCounts</Role>
      <ShortName>WEIGHTED AVERAGE SHARE COUNTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>101300 - Disclosure - EMPLOYEE COMPENSATION PLANS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureEmployeeCompensationPlans</Role>
      <ShortName>EMPLOYEE COMPENSATION PLANS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>101400 - Disclosure - RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>RELATED PARTY TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>200101 - Disclosure - OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureOverviewAndSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>300100 - Disclosure - OVERVIEW AND BASIS OF PRESENTATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentationTables</Role>
      <ShortName>OVERVIEW AND BASIS OF PRESENTATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentation</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>300200 - Disclosure - ACQUISITIONS AND DIVESTITURES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAcquisitionsAndDivestituresTables</Role>
      <ShortName>ACQUISITIONS AND DIVESTITURES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>300300 - Disclosure - SEGMENT INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureSegmentInformationTables</Role>
      <ShortName>SEGMENT INFORMATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureSegmentInformation</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>300400 - Disclosure - ACCOUNTS RECEIVABLE AND SIGNIFICANT CLIENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccountsReceivableAndSignificantClientsTables</Role>
      <ShortName>ACCOUNTS RECEIVABLE AND SIGNIFICANT CLIENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>300500 - Disclosure - GOODWILL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureGoodwillTables</Role>
      <ShortName>GOODWILL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureGoodwill</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>300600 - Disclosure - DERIVATIVES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivativesTables</Role>
      <ShortName>DERIVATIVES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDerivatives</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>300700 - Disclosure - FAIR VALUE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureFairValueTables</Role>
      <ShortName>FAIR VALUE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureFairValue</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>301100 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLossTables</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLoss</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>301200 - Disclosure - WEIGHTED AVERAGE SHARE COUNTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureWeightedAverageShareCountsTables</Role>
      <ShortName>WEIGHTED AVERAGE SHARE COUNTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureWeightedAverageShareCounts</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>400105 - Disclosure - OVERVIEW AND BASIS OF PRESENTATION (TABLES) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentationTablesDetails</Role>
      <ShortName>OVERVIEW AND BASIS OF PRESENTATION (TABLES) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentationTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>400130 - Disclosure - OVERVIEW AND BASIS OF PRESENTATION (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentationNarrativeDetails</Role>
      <ShortName>OVERVIEW AND BASIS OF PRESENTATION (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureOverviewAndBasisOfPresentationTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>400200 - Disclosure - ACQUISITIONS ASSETS ACQUIRED (TABLES) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAcquisitionsAssetsAcquiredTablesDetails</Role>
      <ShortName>ACQUISITIONS ASSETS ACQUIRED (TABLES) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>400210 - Disclosure - ACQUISITIONS AND DIVESTITURES (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAcquisitionsAndDivestituresNarrativeDetails</Role>
      <ShortName>ACQUISITIONS AND DIVESTITURES (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureAcquisitionsAndDivestituresTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>400300 - Disclosure - SEGMENT INFORMATION (SEGMENT FINANCIALS) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureSegmentInformationSegmentFinancialsDetails</Role>
      <ShortName>SEGMENT INFORMATION (SEGMENT FINANCIALS) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureSegmentInformationTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>400310 - Disclosure - SEGMENT INFORMATION (REVENUE GEOGRAPHY) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureSegmentInformationRevenueGeographyDetails</Role>
      <ShortName>SEGMENT INFORMATION (REVENUE GEOGRAPHY) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureSegmentInformationTables</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>400410 - Disclosure - ACCOUNTS RECEIVABLE (SCHEDULE OF CHANGE IN ALLOWANCE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccountsReceivableScheduleOfChangeInAllowanceDetails</Role>
      <ShortName>ACCOUNTS RECEIVABLE (SCHEDULE OF CHANGE IN ALLOWANCE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureAccountsReceivableAndSignificantClientsTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>400430 - Disclosure - ACCOUNTS RECEIVABLE AND SIGNIFICANT CLIENTS(NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccountsReceivableAndSignificantClientsNarrativeDetails</Role>
      <ShortName>ACCOUNTS RECEIVABLE AND SIGNIFICANT CLIENTS(NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>400440 - Disclosure - Receivables Sales Agreement - Additional Information (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureReceivablesSalesAgreementAdditionalInformationNarrativeDetail</Role>
      <ShortName>Receivables Sales Agreement - Additional Information (Narrative) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>400500 - Disclosure - GOODWILL (GOODWILL ROLLFORWARD) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureGoodwillGoodwillRollforwardDetails</Role>
      <ShortName>GOODWILL (GOODWILL ROLLFORWARD) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureGoodwillTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>400600 - Disclosure - DERIVATIVES (OCI ROLLFORWARD) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivativesOciRollforwardDetails</Role>
      <ShortName>DERIVATIVES (OCI ROLLFORWARD) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDerivativesTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>400610 - Disclosure - DERIVATIVES (NOTIONAL TABLE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivativesNotionalTableDetails</Role>
      <ShortName>DERIVATIVES (NOTIONAL TABLE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDerivativesTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>400630 - Disclosure - DERIVATIVES (BALANCE SHEET CLASSIFICATION) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivativesBalanceSheetClassificationDetails</Role>
      <ShortName>DERIVATIVES (BALANCE SHEET CLASSIFICATION) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDerivativesTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>400640 - Disclosure - DERIVATIVES (INCOME STATEMENT CLASSIFICATION) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivativesIncomeStatementClassificationDetails</Role>
      <ShortName>DERIVATIVES (INCOME STATEMENT CLASSIFICATION) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDerivativesTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>400650 - Disclosure - DERIVATIVES (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDerivativesNarrativeDetails</Role>
      <ShortName>DERIVATIVES (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDerivativesTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>400700 - Disclosure - FAIR VALUE (DERIVATIVES TABLE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureFairValueDerivativesTableDetails</Role>
      <ShortName>FAIR VALUE (DERIVATIVES TABLE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureFairValueTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>400710 - Disclosure - FAIR VALUE (FAIR VALUE ASSETS AND LIABILITIES) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureFairValueFairValueAssetsAndLiabilitiesDetails</Role>
      <ShortName>FAIR VALUE (FAIR VALUE ASSETS AND LIABILITIES) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureFairValueTables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>400720 - Disclosure - FAIR VALUE (CONTINGENT CONSIDERATION TABLE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureFairValueContingentConsiderationTableDetails</Role>
      <ShortName>FAIR VALUE (CONTINGENT CONSIDERATION TABLE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureFairValueTables</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>400730 - Disclosure - FAIR VALUE (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureFairValueNarrativeDetails</Role>
      <ShortName>FAIR VALUE (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureFairValueTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>400800 - Disclosure - INCOME TAXES (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureIncomeTaxesNarrativeDetails</Role>
      <ShortName>INCOME TAXES (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureIncomeTaxes</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>400920 - Disclosure - COMMITMENTS AND CONTINGENCIES (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureCommitmentsAndContingenciesNarrativeDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>401000 - Disclosure - DEFERRED REVENUE AND REMAINING PERFORMANCE OBLIGATIONS (NARRATIVE") (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureDeferredRevenueAndRemainingPerformanceObligationsNarrativeDetails</Role>
      <ShortName>DEFERRED REVENUE AND REMAINING PERFORMANCE OBLIGATIONS (NARRATIVE") (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureDeferredRevenueAndRemainingPerformanceObligations</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>401100 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (ROLLFORWARD TABLE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLossRollforwardTableDetails</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (ROLLFORWARD TABLE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>401110 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (INCOME STATEMENT CLASSIFICATION TABLE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLossIncomeStatementClassificationTableDetails</Role>
      <ShortName>ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (INCOME STATEMENT CLASSIFICATION TABLE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>401200 - Disclosure - WEIGHTED AVERAGE SHARE COUNTS (DILUTED SHARES TABLE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureWeightedAverageShareCountsDilutedSharesTableDetails</Role>
      <ShortName>WEIGHTED AVERAGE SHARE COUNTS (DILUTED SHARES TABLE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureWeightedAverageShareCountsTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>401210 - Disclosure - WEIGHTED AVERAGE SHARE COUNTS (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureWeightedAverageShareCountsNarrativeDetails</Role>
      <ShortName>WEIGHTED AVERAGE SHARE COUNTS (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureWeightedAverageShareCountsTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>401300 - Disclosure - EQUITY-BASED COMPENSATION PLANS (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureEquityBasedCompensationPlansNarrativeDetails</Role>
      <ShortName>EQUITY-BASED COMPENSATION PLANS (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ttec-20220331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>401400 - Disclosure - RELATED PARTY TRANSACTIONS (NARRATIVE) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://teletech.com/role/DisclosureRelatedPartyTransactionsNarrativeDetails</Role>
      <ShortName>RELATED PARTY TRANSACTIONS (NARRATIVE) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://teletech.com/role/DisclosureRelatedPartyTransactions</ParentRole>
      <Position>60</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" original="ttec-20220331x10q.htm">ttec-20220331x10q.htm</File>
    <File>ttec-20220331.xsd</File>
    <File>ttec-20220331_cal.xml</File>
    <File>ttec-20220331_def.xml</File>
    <File>ttec-20220331_lab.xml</File>
    <File>ttec-20220331_pre.xml</File>
    <File>ttec-20220331xex10d35.htm</File>
    <File>ttec-20220331xex10d84.htm</File>
    <File>ttec-20220331xex31d1.htm</File>
    <File>ttec-20220331xex31d2.htm</File>
    <File>ttec-20220331xex32d1.htm</File>
    <File>ttec-20220331xex32d2.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="720">http://fasb.org/us-gaap/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2021q4</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
