v3.26.1
Computation of Basic and Diluted Earnings Per Common Share Attributable to Teradyne (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 28, 2026
Jun. 29, 2025
Jun. 28, 2026
Jun. 29, 2025
Net Income Loss Per Common Share        
Net Income (Loss) $ 374,533 $ 78,372 $ 773,442 $ 177,269
Weighted average common shares-basic 156,470 159,967 156,440 160,734
Employee stock purchase plan 0 6 2 26
Dilutive potential common shares 1,223 168 1,224 331
Weighted average common shares-diluted 157,693 160,135 157,664 161,065
Earnings per common share attributable to Teradyne - basic $ 2.39 $ 0.49 $ 4.94 $ 1.1
Earnings per common share attributable to Teradyne - diluted $ 2.38 $ 0.49 $ 4.91 $ 1.1
Restricted Stock Units        
Net Income Loss Per Common Share        
Incremental shares attributable to share based payment arrangements 1,142 160 1,145 302
Employee Stock Option [Member]        
Net Income Loss Per Common Share        
Incremental shares attributable to share based payment arrangements 81 2 77 3