Computation of Basic and Diluted Net Income Per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 30, 2014		Mar. 31, 2013
Net Income Loss Per Common Share
Net income for basic and diluted net income per share	$ 929		$ 6,589
Weighted average common shares-basic	193,311		189,686
Incremental shares from assumed conversion of convertible notes	20,052	[1]	23,386	[1]
Convertible note hedge warrant shares	20,942	[2]	18,859	[2]
Employee stock purchase plan	22		27
Dilutive potential common shares	43,173		45,071
Weighted average common shares-diluted	236,484		234,757
Net income per common share-basic	$ 0.00		$ 0.03
Net income per common share-diluted	$ 0.00		$ 0.03
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements	1,051		1,123
Stock Option
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements	1,106		1,676

[1] Incremental shares from conversion of the convertible notes for the three months ended March 30, 2014 were calculated using the difference between the average Teradyne stock price from January 1, 2014 through March 12, 2014 and the conversion price of $5.4750, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the convertible debt, was divided by the average Teradyne stock price for the period from January 1, 2014 to March 12, 2014 and adjusted for the number of days the convertible notes were outstanding during the three months ended March 30, 2014. Incremental shares from assumed conversion of the convertible notes for the three months ended March 31, 2013 were calculated using the difference between the average Teradyne stock price for the period and the conversion price of $5.4750, multiplied by the 34.7 million shares to be issued upon conversion. The result of this calculation, representing the total intrinsic value of the convertible debt, was divided by the average Teradyne stock price for the period.

[2] Convertible note hedge warrant shares for the three months ended March 30, 2014 and March 31, 2013 are calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.6650, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the warrant, is divided by the average Teradyne stock price for the period.