Debt - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended			3 Months Ended		9 Months Ended				1 Months Ended		3 Months Ended	9 Months Ended	1 Months Ended
	Mar. 31, 2009 Y	Mar. 30, 2012	Sep. 29, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 29, 2013 Convertible Notes Hedge Warrant	Sep. 30, 2012 Convertible Notes Hedge Warrant	Sep. 29, 2013 Convertible Notes Hedge Warrant	Sep. 30, 2012 Convertible Notes Hedge Warrant	Mar. 31, 2009 Convertible Notes Hedge Warrant	Sep. 29, 2013 Convertible Senior Notes	Apr. 30, 2009 4.50% Convertible Senior Notes Due March 15, 2014	Mar. 31, 2009 4.50% Convertible Senior Notes Due March 15, 2014	Sep. 29, 2013 4.50% Convertible Senior Notes Due March 15, 2014 D	Sep. 29, 2013 4.50% Convertible Senior Notes Due March 15, 2014	Nov. 08, 2013 4.50% Convertible Senior Notes Due March 15, 2014 Subsequent Event
Debt Instrument
Borrowings from local bank	$ 10,000,000
Term of loan, years	5
Debt instrument, interest rate, stated percentage	0.80%											4.50%
Loan collateralized by real estate mortgage	6,000,000
Unsecured loan	4,000,000
Semiannual principal payments of loan		1,000,000		1,000,000
Outstanding loan principal amount			2,000,000
Aggregate principal amount			189,998,000		190,000,000							190,000,000
Senior notes maturity date												March 15, 2014
Initial conversion rate in number of shares															182.65
Additional aggregate principal amount															1,000
Initial debt conversion price			$ 5.48			$ 7.67	$ 7.67	$ 7.67	$ 7.67	$ 7.67			$ 5.48
Debt conversion premium percentage													25.00%
Last reported sale price per share of debt													$ 4.38
Initial conversion rate			The Notes may be converted, at the option of the holder, under certain circumstances and during certain periods, at an initial conversion rate of approximately 182.65 shares of Teradyne's common stock per $1,000 principal amount of Notes, which is equivalent to an initial conversion price of approximately $5.48, a 25% conversion premium based on the last reported sale price of $4.38 per share of Teradyne's common stock on March 31, 2009.
Threshold trading days														20
Threshold consecutive trading days														30 days
Threshold percentage of stock price trigger														130.00%
Stock price trigger																$ 2,000
Antidilution adjustments, shares			34,703,196			34,700,000	34,700,000	34,700,000	34,700,000
Convertible note hedges			64,600,000
Strike price per share of warrant	$ 7.67
Percentage of warrant price in excess of closing price of common stock	75.00%
Proceeds from warrants	43,000,000
Warrants conversion premium percentage	75.00%
Unamortized discount			8,448,000		20,104,000						8,400,000
Amortization period of unamortized discount, months			6 months
Carrying amount of equity component			63,400,000
Debt instrument conversion price			$ 5.48
If-converted value of notes			$ 579,900,000