Computation of Basic and Diluted Net Income (loss) Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016
Net Income Loss Per Common Share
Net income (loss) for basic and diluted net income (loss) per common share		$ 174,976	$ (223,546)	$ 260,197	$ (173,560)
Weighted average common shares-basic		198,774	203,018	199,390	203,645
Incremental shares from assumed conversion of convertible note	[1]	752		376
Employee stock purchase plan		63		36
Dilutive potential common shares		2,755		2,342
Weighted average common shares-diluted		201,529	203,018	201,732	203,645
Net income (loss) per common share-basic		$ 0.88	$ (1.10)	$ 1.30	$ (0.85)
Net income (loss) per common share-diluted		$ 0.87	$ (1.10)	$ 1.29	$ (0.85)
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		1,622		1,576
Stock Options
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		318		354

[1] Incremental shares from assumed conversion of the convertible notes for the three and six months ended July 2, 2017 are calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.84, multiplied by the 14.4 million shares that would be issued upon conversion. The result of this calculation, representing the total intrinsic value of the convertible debt, is divided by the average Teradyne stock price for the period.