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Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail) (TSR Performance-Based Restricted Stock Units) | 3 Months Ended
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Apr. 05, 2015 | Mar. 30, 2014
TSR Performance-Based Restricted Stock Units |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |
Risk-free interest rate | 0.77%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember | 0.75%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember
Teradyne volatility-historical | 28.20%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember | 36.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember
Philadelphia Semiconductor Index volatility-historical | 19.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember | 24.60%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember
Dividend yield | 1.33%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember | 1.25%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = ter_ShareholderReturnPerformanceBasedRestrictedStockUnitsMember

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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Details
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