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Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2015
Feb. 22, 2016
Jul. 02, 2015
Document Information      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2015    
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus FY    
Trading Symbol TER    
Entity Registrant Name TERADYNE, INC    
Entity Central Index Key 0000097210    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   204,336,493  
Entity Public Float     $ 4,100,000,000