Computation of Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 29, 2024	Oct. 01, 2023	Sep. 29, 2024	Oct. 01, 2023
Net Income Loss Per Common Share
Net Income (Loss)		$ 145,649	$ 128,116	$ 396,119	$ 331,698
Weighted average common shares-basic		163,002,000	153,762,000	157,951,000	154,809,000
Convertible note hedge warrant shares	[1]	460,000	9,168,000	4,751,000	9,009,000
Incremental shares from assumed conversion of convertible notes	[2]	0	629,000	0	762,000
Incremental Common Shares Attributable to Dilutive Effect of Equity Unit Purchase Agreements		10,000	10,000	5	8
Weighted Average Number of Shares Outstanding, Diluted, Adjustment, Total		1,251,000	10,288,000	5,406,000	10,228,000
Weighted average common shares-diluted		164,253,000	164,050,000	163,357,000	165,037,000
Earnings Per Share, Basic		$ 0.89	$ 0.83	$ 2.51	$ 2.14
Earnings Per Share, Diluted		$ 0.89	$ 0.78	$ 2.42	$ 2.01
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		768,000	455,000	637	410
Employee Stock Option [Member]
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		13,000	26,000	13	39

[1] Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price, multiplied by the number of warrant shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period.

[2] Incremental shares from assumed conversion of the convertible notes were calculated using the difference between the average Teradyne stock price for the period and the conversion price, multiplied by the number of convertible notes shares. The result of this calculation, representing the total intrinsic value of the convertible notes, was divided by the average Teradyne stock price for the period.