Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Aug. 05, 2019
Document and Entity Information [Abstract]    
Amendment Flag false  
Document Type 10-Q  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0000097210  
Current Fiscal Year End Date --12-31  
Document Period End Date Jun. 30, 2019  
Entity Registrant Name TERADYNE, INC  
Entity Filer Category Large Accelerated Filer  
Trading Symbol TER  
Document Quarterly Report true  
Document Transition Report false  
Entity Interactive Data Current Yes  
Entity Current Reporting Status Yes  
Title of 12(b) Security Common Stock  
Security Exchange Name NASDAQ  
Entity File Number 001-06462  
Entity Incorporation, State or Country Code MA  
Entity Tax Identification Number 04-2272148  
Entity Address, Address Line One 600 Riverpark Drive  
Entity Address, City or Town North Reading  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 01864  
City Area Code 978  
Local Phone Number 370-2700  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   169,945,820