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Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail) (USD $)
In Thousands, unless otherwise specified
 0 Months Ended 12 Months Ended
Oct. 31, 2014
Oct. 25, 2013
Dec. 31, 2014
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]      
Discount rate 4.70%us-gaap_FairValueInputsDiscountRate 5.20%us-gaap_FairValueInputsDiscountRate  
Significant Unobservable Inputs (Level 3) | Income Approach Valuation Technique      
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]      
Contingent consideration     1,600us-gaap_BusinessCombinationContingentConsiderationLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= us-gaap_IncomeApproachValuationTechniqueMember
Revenue Earnout      
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]      
Target achievement, probability     0.00%ter_FairValueInputsProbabilityOfAchievingTarget
/ us-gaap_ContingentConsiderationByTypeAxis
= ter_RevenueEarnoutMember
Customer Orders      
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]      
Target achievement, probability     40.00%ter_FairValueInputsProbabilityOfAchievingTarget
/ us-gaap_ContingentConsiderationByTypeAxis
= ter_CustomerOrdersMember
Discount rate     5.20%us-gaap_FairValueInputsDiscountRate
/ us-gaap_ContingentConsiderationByTypeAxis
= ter_CustomerOrdersMember