<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.2.0.727</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>296</ContextCount>
  <ElementCount>347</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>77</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>101 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>103 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/StatementOfFinancialPositionClassified</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>104 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>105 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/StatementOfIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>106 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/StatementOfOtherComprehensiveIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>107 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/StatementOfOtherComprehensiveIncomeParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>108 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/StatementOfCashFlowsIndirect</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>109 - Disclosure - The Company</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsNatureOfOperations</Role>
      <ShortName>The Company</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>110 - Disclosure - Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlock</Role>
      <ShortName>Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>111 - Disclosure - Recently Issued Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDescriptionOfNewAccountingPronouncementsNotYetAdopted</Role>
      <ShortName>Recently Issued Accounting Pronouncements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>112 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsBusinessCombinationDisclosureTextBlock</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>113 - Disclosure - Financial Instruments and Derivatives</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock</Role>
      <ShortName>Financial Instruments and Derivatives</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>114 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>115 - Disclosure - Prepayments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsPrepaidExpenseDisclosureTextBlock</Role>
      <ShortName>Prepayments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>116 - Disclosure - Deferred Revenue and Customer Advances</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDeferredRevenueDisclosureTextBlock</Role>
      <ShortName>Deferred Revenue and Customer Advances</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>117 - Disclosure - Product Warranty</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsProductWarrantyDisclosureTextBlock</Role>
      <ShortName>Product Warranty</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>118 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>119 - Disclosure - Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlock</Role>
      <ShortName>Accumulated Other Comprehensive Income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>120 - Disclosure - Goodwill and Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsGoodwillAndIntangibleAssetsDisclosureTextBlock</Role>
      <ShortName>Goodwill and Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>121 - Disclosure - Net Income per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlock</Role>
      <ShortName>Net Income per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>122 - Disclosure - Restructuring and Other</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsRestructuringAndRelatedActivitiesDisclosureTextBlock</Role>
      <ShortName>Restructuring and Other</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>123 - Disclosure - Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsPensionAndOtherPostretirementBenefitsDisclosureTextBlock</Role>
      <ShortName>Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>124 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>125 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlock</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>126 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsSegmentReportingDisclosureTextBlock</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>127 - Disclosure - Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsStockholdersEquityNoteDisclosureTextBlock</Role>
      <ShortName>Shareholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>128 - Disclosure - Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlockPolicies</Role>
      <ShortName>Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlock</ParentRole>
      <Position>27</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>129 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsBusinessCombinationDisclosureTextBlockTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsBusinessCombinationDisclosureTextBlock</ParentRole>
      <Position>28</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>130 - Disclosure - Financial Instruments and Derivatives (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</Role>
      <ShortName>Financial Instruments and Derivatives (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock</ParentRole>
      <Position>29</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>131 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</ParentRole>
      <Position>30</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>132 - Disclosure - Prepayments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsPrepaidExpenseDisclosureTextBlockTables</Role>
      <ShortName>Prepayments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsPrepaidExpenseDisclosureTextBlock</ParentRole>
      <Position>31</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>133 - Disclosure - Deferred Revenue and Customer Advances (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDeferredRevenueDisclosureTextBlockTables</Role>
      <ShortName>Deferred Revenue and Customer Advances (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDeferredRevenueDisclosureTextBlock</ParentRole>
      <Position>32</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>134 - Disclosure - Product Warranty (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsProductWarrantyDisclosureTextBlockTables</Role>
      <ShortName>Product Warranty (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsProductWarrantyDisclosureTextBlock</ParentRole>
      <Position>33</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>135 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock</ParentRole>
      <Position>34</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>136 - Disclosure - Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlockTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlock</ParentRole>
      <Position>35</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>137 - Disclosure - Goodwill and Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsGoodwillAndIntangibleAssetsDisclosureTextBlockTables</Role>
      <ShortName>Goodwill and Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsGoodwillAndIntangibleAssetsDisclosureTextBlock</ParentRole>
      <Position>36</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>138 - Disclosure - Net Income per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlockTables</Role>
      <ShortName>Net Income per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlock</ParentRole>
      <Position>37</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>139 - Disclosure - Retirement Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsPensionAndOtherPostretirementBenefitsDisclosureTextBlockTables</Role>
      <ShortName>Retirement Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsPensionAndOtherPostretirementBenefitsDisclosureTextBlock</ParentRole>
      <Position>38</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>140 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsSegmentReportingDisclosureTextBlockTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsSegmentReportingDisclosureTextBlock</ParentRole>
      <Position>39</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>141 - Disclosure - The Company - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureTheCompanyAdditionalInformation</Role>
      <ShortName>The Company - Additional information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>142 - Disclosure - Acquisitions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureAcquisitionsAdditionalInformation</Role>
      <ShortName>Acquisitions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>143 - Disclosure - Allocation of Final Purchase Price (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureAllocationOfFinalPurchasePrice</Role>
      <ShortName>Allocation of Final Purchase Price (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>144 - Disclosure - Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureComponentsOfIntangibleAssetsAndTheirEstimatedUsefulLivesAtAcquisitionDate</Role>
      <ShortName>Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>145 - Disclosure - Pro Forma Results Under Acquisition (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureProFormaResultsUnderAcquisition</Role>
      <ShortName>Pro Forma Results Under Acquisition (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>146 - Disclosure - Financial Instruments and Derivatives - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureFinancialInstrumentsAndDerivativesAdditionalInformation</Role>
      <ShortName>Financial Instruments and Derivatives - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>147 - Disclosure - Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfFairValueOfFinancialAssetsAndLiabilitiesMeasuredOnRecurringBasis</Role>
      <ShortName>Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>148 - Disclosure - Schedule of Reported Financial Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfReportedFinancialAssetsAndLiabilities</Role>
      <ShortName>Schedule of Reported Financial Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>149 - Disclosure - Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfChangesInFairValueOfLevel3ContingentConsideration</Role>
      <ShortName>Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>150 - Disclosure - Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfChangesInFairValueOfLevel3ContingentConsiderationParenthetical</Role>
      <ShortName>Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>151 - Disclosure - Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureQuantitativeInformationAssociatedWithFairValueMeasurementOfLevel3FinancialInstrument</Role>
      <ShortName>Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>152 - Disclosure - Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfCarryingAmountsAndFairValuesOfFinancialInstruments</Role>
      <ShortName>Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>153 - Disclosure - Schedule of Available for Sale Marketable Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfAvailableForSaleMarketableSecurities</Role>
      <ShortName>Schedule of Available for Sale Marketable Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>154 - Disclosure - Schedule of Reported Available for Sale Marketable Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfReportedAvailableForSaleMarketableSecurities</Role>
      <ShortName>Schedule of Reported Available for Sale Marketable Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>155 - Disclosure - Contractual Maturities of Investments Held (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureContractualMaturitiesOfInvestmentsHeld</Role>
      <ShortName>Contractual Maturities of Investments Held (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>156 - Disclosure - Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfEffectOfDerivativeInstrumentsInStatementOfOperationsRecognized</Role>
      <ShortName>Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>157 - Disclosure - Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureDebtAdditionalInformation</Role>
      <ShortName>Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>158 - Disclosure - Interest Expense on Convertible Senior Notes (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureInterestExpenseOnConvertibleSeniorNotes</Role>
      <ShortName>Interest Expense on Convertible Senior Notes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>159 - Disclosure - Schedule of Prepayments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfPrepayments</Role>
      <ShortName>Schedule of Prepayments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>160 - Disclosure - Deferred Revenue and Customer Advances (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureDeferredRevenueAndCustomerAdvances</Role>
      <ShortName>Deferred Revenue and Customer Advances (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.teradyne.com/taxonomy/role/NotesToFinancialStatementsDeferredRevenueDisclosureTextBlockTables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>161 - Disclosure - Warranty Accrual Included in Other Accrued Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureWarrantyAccrualIncludedInOtherAccruedLiabilities</Role>
      <ShortName>Warranty Accrual Included in Other Accrued Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>162 - Disclosure - Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureExtendedProductWarrantyIncludedInShortAndLongTermDeferredRevenueAndCustomerAdvances</Role>
      <ShortName>Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>163 - Disclosure - Stock Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformation</Role>
      <ShortName>Stock Based Compensation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>164 - Disclosure - Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfEstimatedFairValueOfTSRPerformanceBasedRestrictedStockUnitAwardsAssumptions</Role>
      <ShortName>Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>165 - Disclosure - Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfEstimatedFairValueOfStockOptionsGrantUsingBlackScholesOptionPricingModel</Role>
      <ShortName>Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>166 - Disclosure - Changes in Accumulated Other Comprehensive Income (Loss) Balances (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureChangesInAccumulatedOtherComprehensiveIncomeLossBalances</Role>
      <ShortName>Changes in Accumulated Other Comprehensive Income (Loss) Balances (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>167 - Disclosure - Changes in Accumulated Other Comprehensive Income (Loss) Balances (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureChangesInAccumulatedOtherComprehensiveIncomeLossBalancesParenthetical</Role>
      <ShortName>Changes in Accumulated Other Comprehensive Income (Loss) Balances (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>168 - Disclosure - Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureReclassificationOutOfAccumulatedOtherComprehensiveIncomeToStatementOfOperations</Role>
      <ShortName>Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>169 - Disclosure - Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureReclassificationOutOfAccumulatedOtherComprehensiveIncomeToStatementOfOperationsParenthetical</Role>
      <ShortName>Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>170 - Disclosure - Changes in Carrying Amount of Goodwill by Segment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureChangesInCarryingAmountOfGoodwillBySegment</Role>
      <ShortName>Changes in Carrying Amount of Goodwill by Segment (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>171 - Disclosure - Schedule of Amortizable Intangible Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfAmortizableIntangibleAssets</Role>
      <ShortName>Schedule of Amortizable Intangible Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>172 - Disclosure - Goodwill and Intangible Assets - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsAdditionalInformation</Role>
      <ShortName>Goodwill and Intangible Assets - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>173 - Disclosure - Schedule of Estimated Intangible Asset Amortization Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfEstimatedIntangibleAssetAmortizationExpense</Role>
      <ShortName>Schedule of Estimated Intangible Asset Amortization Expense (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>174 - Disclosure - Computation of Basic and Diluted Net Income Per Common Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureComputationOfBasicAndDilutedNetIncomePerCommonShare</Role>
      <ShortName>Computation of Basic and Diluted Net Income Per Common Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>175 - Disclosure - Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureComputationOfBasicAndDilutedNetIncomePerCommonShareParenthetical</Role>
      <ShortName>Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>176 - Disclosure - Net Income Per Common Share - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureNetIncomePerCommonShareAdditionalInformation</Role>
      <ShortName>Net Income Per Common Share - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>177 - Disclosure - Restructuring and Other - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureRestructuringAndOtherAdditionalInformation</Role>
      <ShortName>Restructuring and Other - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>178 - Disclosure - Retirement Plans - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureRetirementPlansAdditionalInformation</Role>
      <ShortName>Retirement Plans - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>179 - Disclosure - Schedule of Net Periodic Pension and Postretirement Cost (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfNetPeriodicPensionAndPostretirementCost</Role>
      <ShortName>Schedule of Net Periodic Pension and Postretirement Cost (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>180 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformation</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>181 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureIncomeTaxesAdditionalInformation</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>182 - Disclosure - Segment Information - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureSegmentInformationAdditionalInformation</Role>
      <ShortName>Segment Information - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>183 - Disclosure - Schedule of Segment Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfSegmentInformation</Role>
      <ShortName>Schedule of Segment Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>184 - Disclosure - Schedule of Segment Reporting Information by Segment Charges (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureScheduleOfSegmentReportingInformationBySegmentCharges</Role>
      <ShortName>Schedule of Segment Reporting Information by Segment Charges (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>185 - Disclosure - Shareholders' Equity - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.teradyne.com/taxonomy/role/DisclosureShareholdersEquityAdditionalInformation</Role>
      <ShortName>Shareholders' Equity - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9999.htm</HtmlFileName>
      <LongName>Uncategorized Items - ter-20150705.xml</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/role/uncategorizedFacts</Role>
      <ShortName>Uncategorized Items - ter-20150705.xml</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">In ''CONDENSED CONSOLIDATED BALANCE SHEETS'', column(s) 3, 4 are contained in other reports, so were removed by flow through suppression.</Log>
    <Log type="Info">In ''CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS'', column(s) 1, 2 are contained in other reports, so were removed by flow through suppression.</Log>
    <Log type="Warn">In ''Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)'', fact us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue with value 2230000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2014-06-29. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)'', fact us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue with value 2230000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2013-12-31. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)'', fact us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue with value 2230000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2014-03-30. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)'', fact us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue with value 2230000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2014-06-29. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)'', fact us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue with value 2230000 and preferred label periodStartLabel, was not shown because there are no facts in a duration starting at 2014-03-30. Change the preferred label role or add facts.</Log>
    <Log type="Warn">In ''Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail)'', fact us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue with value 2230000 and preferred label periodEndLabel, was not shown because there are no facts in a duration ending at 2013-12-31. Change the preferred label role or add facts.</Log>
  </Logs>
  <InputFiles>
    <File>ter-20150705.xml</File>
    <File>ter-20150705_cal.xml</File>
    <File>ter-20150705_def.xml</File>
    <File>ter-20150705_lab.xml</File>
    <File>ter-20150705_pre.xml</File>
    <File>ter-20150705.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>

