Debt - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended				12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended
	Mar. 31, 2009	Mar. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2009	Apr. 06, 2009	Dec. 31, 2013 Convertible Notes Hedge Warrant	Mar. 31, 2009 Convertible Notes Hedge Warrant	Mar. 31, 2009 4.50% Convertible Senior Notes Due March 15, 2014	Dec. 31, 2013 4.50% Convertible Senior Notes Due March 15, 2014 D M	Feb. 27, 2014 4.50% Convertible Senior Notes Due March 15, 2014 Subsequent Event	Dec. 31, 2013 4.50% Convertible Senior Notes Due March 15, 2014 Option One	Dec. 31, 2013 4.50% Convertible Senior Notes Due March 15, 2014 Option Two	Apr. 30, 2009 Convertible Senior Notes	Dec. 31, 2013 Convertible Senior Notes	Apr. 30, 2009 4.50% Convertible Senior Notes	Dec. 31, 2013 Current Debt
Debt Instrument
Borrowings from local bank	$ 10,000,000
Term of loan, years	5 years
Debt instrument, interest rate, stated percentage	0.80%									4.50%
Loan collateralized by real estate mortgage	6,000,000
Loan collateralized by real estate mortgage net book value				10,800,000
Unsecured loan	4,000,000
Semiannual principal payments of loan		1,000,000	1,000,000
Outstanding loan principal amount																		1,000,000
Aggregate principal amount				189,998,000	190,000,000	190,000,000	190,000,000			175,000,000						190,000,000
Additional aggregate principal amount											1,000				15,000,000
Senior notes maturity date																	Mar. 15, 2014
Initial conversion rate in number of shares											182.65
Initial debt conversion price				$ 5.48				$ 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, 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 consecutive trading days													5 days	30 days
Conversion period before expiration, period, months											3
Trading days used to determine average price per share											25 days
Maximum price per Note for each day of that measurement period											98.00%
Threshold trading days											20
Threshold percentage of stock price trigger											130.00%
Stock price trigger												$ 2,000
Percentage of principal amount				100.00%
Percentage of acquisition of total voting shares				50.00%
Antidilution adjustments, shares				34,703,196				34,700,000
Convertible note hedges				64,600,000
Strike price per share of warrant	$ 7.67
Warrants settled on a daily basis	534,000
Warrant settlement period	65 days
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%
Financing transaction							163,000,000
Carrying amount of equity component				63,400,000
Effective annual interest rate on notes				14.50%
Term of amortization, years																Five
Debt issuance costs, amortized to interest expense																4,100,000
Debt issuance costs																200,000
Unamortized discount				4,290,000	20,104,000											4,300,000
Debt instrument conversion price				$ 5.48
If-converted value of notes				$ 611,500,000