Teradyne (TER) 10-Q 8 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 29, 2014	Aug. 01, 2014
Document Information	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	29-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'TER	'
Entity Registrant Name	'TERADYNE, INC	'
Entity Central Index Key	'0000097210	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	204,676,850

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$254,625	$341,638
Marketable securities	488,439	586,882
Accounts receivable, less allowance for doubtful accounts of $2,461 and $2,912 at June 29, 2014 and December 31, 2013, respectively	300,767	157,642
Inventories:	'	'
Parts	70,444	84,232
Assemblies in process	15,191	15,539
Finished goods	41,239	38,168
Inventory, Net, Total	126,874	137,939
Deferred tax assets	68,460	72,478
Prepayments	110,473	136,374
Other current assets	4,989	7,324
Total current assets	1,354,627	1,440,277
Net property, plant and equipment	308,521	275,236
Marketable securities	364,077	271,078
Deferred tax assets	5,810	5,217
Other assets	10,927	14,591
Retirement plans assets	9,134	9,342
Intangible assets, net	215,748	252,291
Goodwill	361,819	361,792
Total assets	2,630,663	2,629,824
Current liabilities:	'	'
Accounts payable	102,214	62,874
Accrued employees' compensation and withholdings	86,765	95,619
Deferred revenue and customer advances	63,968	55,404
Other accrued liabilities	93,103	63,712
Accrued income taxes	15,182	11,360
Current debt	'	186,663
Total current liabilities	361,232	475,632
Long-term deferred revenue and customer advances	18,992	13,756
Retirement plans liabilities	92,485	91,517
Deferred tax liabilities	39,616	40,686
Long-term other accrued liabilities	16,865	23,139
Total liabilities	529,190	644,730
Commitments and contingencies (Note O)	'	'
SHAREHOLDERS' EQUITY	'	'
Common stock, $0.125 par value, 1,000,000 shares authorized, 196,321 shares and 191,731 shares issued and outstanding at June 29, 2014 and December 31, 2013, respectively	24,540	23,966
Additional paid-in capital	1,414,513	1,390,896
Accumulated other comprehensive income	5,709	4,000
Retained earnings	656,711	566,232
Total shareholders' equity	2,101,473	1,985,094
Total liabilities and shareholders' equity	$2,630,663	$2,629,824

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, except Per Share data, unless otherwise specified
Accounts receivable, less allowance for doubtful accounts	$2,461	$2,912
Common stock, par value	$0.13	$0.13
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares issued	196,321	191,731
Common stock, shares outstanding	196,321	191,731

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended				6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 29, 2014		Jun. 30, 2013		Jun. 29, 2014		Jun. 30, 2013
Net revenues:	'		'		'		'
Products	$452,488		$363,087		$707,874		$577,387
Services	73,079		65,802		138,703		131,869
Total net revenues	525,567		428,889		846,577		709,256
Cost of revenues:	'		'		'		'
Cost of products	202,411		158,411		326,859		255,204
Cost of services	32,743		29,245		62,258		59,402
Total cost of revenues	235,154		187,656		389,117		314,606
Gross profit	290,413		241,233		457,460		394,650
Operating expenses:	'		'		'		'
Engineering and development	73,414		67,773		140,499		130,524
Selling and administrative	77,489		69,230		155,492		137,120
Acquired intangible assets amortization	18,271		18,063		36,542		36,099
Restructuring and other	572		259		572		591
Total operating expenses	169,746		155,325		333,105		304,334
Income from operations	120,667		85,908		124,355		90,316
Interest income	1,266		903		2,302		1,975
Interest expense and other	541		6,454		7,138		13,360
Income before income taxes	121,392	[1],[2]	80,357	[1],[2]	119,519	[1],[2]	78,931	[1],[2]
Income tax provision	20,187		13,801		17,385		5,786
Net income	$101,205		$66,556		$102,134		$73,145
Net income per common share:	'		'		'		'
Basic	$0.52		$0.35		$0.53		$0.38
Diluted	$0.47		$0.28		$0.45		$0.31
Weighted average common shares-basic	194,408		190,569		193,860		190,128
Weighted average common shares-diluted	216,568		234,909		226,526		234,833
Cash dividend declared per common share	'		'		$0.06		'
[1]	Pension and postretirement actuarial gains and losses, interest income, and interest expense and other are included in Corporate and Eliminations.
[2]	Included in the income (loss) before income taxes for each of the segments are charges and credits for the three and six months ended June 29, 2014 and June 30, 2013 that include restructuring and other, and provision for excess and obsolete inventory, as follows:

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014		Jun. 30, 2013		Jun. 29, 2014		Jun. 30, 2013
Net income	$101,205		$66,556		$102,134		$73,145
Other comprehensive income (loss):	'		'		'		'
Net unrealized gains (losses) on marketable securities arising during period, net of tax of $558, $(841), $1,242, $(726)	1,165		-1,463		2,304		-1,263
Less: Reclassification adjustment for net gains included in net income, net of tax of $(141), $(39), $(243), $(122)	-272		-68		-448		-212
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total	893		-1,531		1,856		-1,475
Defined benefit pension and post-retirement plans:	'		'		'		'
Amortization of net prior service benefit included in net periodic pension expense and post-retirement income, net of tax of $(42), $(40), $(85), $(79)	-74	[1]	-69	[1]	-147	[1]	-138	[1]
Other comprehensive income (loss)	819		-1,600		1,709		-1,613
Comprehensive income	$102,024		$64,956		$103,843		$71,532
[1]	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: "Retirement Plans."

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Net unrealized gains on marketable securities arising during period, tax	$558	($841)	$1,242	($726)
Reclassification adjustment for net gains included in net income, tax	-141	-39	-243	-122
Amortization of prior service benefit, tax	($42)	($40)	($85)	($79)

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013
Cash flows from operating activities:	'	'
Net income	$102,134	$73,145
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	33,785	27,552
Amortization	42,990	46,052
Stock-based compensation	23,530	18,077
Provision for excess and obsolete inventory	15,071	5,775
Deferred taxes	-5,697	-15,230
Tax benefit related to stock options and restricted stock units	-1,671	-1,584
Retirement plans actuarial gains	'	-1,359
Other	1,165	24
Changes in operating assets and liabilities:	'	'
Accounts receivable	-143,125	-74,785
Inventories	18,469	26,373
Prepayments and other assets	27,000	-17,277
Accounts payable and other accrued expenses	52,796	-15,428
Deferred revenue and customer advances	13,800	-2,811
Retirement plans contributions	-2,388	-2,511
Accrued income taxes	5,495	2,964
Net cash provided by operating activities	183,354	68,977
Cash flows from investing activities:	'	'
Purchases of property, plant and equipment	-91,389	-50,798
Purchases of marketable securities	-523,306	-458,070
Proceeds from maturities of marketable securities	377,436	268,546
Proceeds from sales of marketable securities	152,818	50,255
Proceeds from life insurance	4,391	'
Net cash used for investing activities	-80,050	-190,067
Cash flows from financing activities:	'	'
Issuance of common stock under employee stock purchase and stock options plans	10,643	9,638
Tax benefit related to stock options and restricted stock units	1,671	1,584
Payments of dividend	-11,656	'
Payments of long-term debt	-190,975	-1,063
Payments of contingent consideration	'	-388
Net cash (used for) provided by financing activities	-190,317	9,771
Decrease in cash and cash equivalents	-87,013	-111,319
Cash and cash equivalents at beginning of period	341,638	338,920
Cash and cash equivalents at end of period	$254,625	$227,601

The_Company

The Company	6 Months Ended
	Jun. 29, 2014
The Company	'
	A. The Company
	Teradyne, Inc. (the “Company” or “Teradyne”) is a leading global supplier of automatic test equipment. Teradyne’s automatic test equipment products and services include:
		•	semiconductor test (“Semiconductor Test”) systems;
		•	wireless test (“Wireless Test”) systems; and
		•	military/aerospace (“Mil/Aero”) test instrumentation and systems, storage test (“Storage Test”) systems, and circuit-board test (“Production Board Test”) systems (collectively these products represent “System Test”).

Accounting_Policies

Accounting Policies	6 Months Ended
	Jun. 29, 2014
Accounting Policies	'
	B. Accounting Policies
	Basis of Presentation
	The consolidated interim financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated. These interim financial statements are unaudited and reflect all normal recurring adjustments that are, in the opinion of management, necessary for the fair presentation of such interim financial statements. Certain prior year’s amounts were reclassified to conform to the current year presentation. The December 31, 2013 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.
	The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in Teradyne’s Annual Report on Form 10-K, filed with the U.S. Securities and Exchange Commission (“SEC”) on February 28, 2014, for the year ended December 31, 2013.
	Preparation of Financial Statements and Use of Estimates
	The preparation of consolidated financial statements requires management to make estimates and judgments that affect the amounts reported in the financial statements. Actual results may differ significantly from these estimates.

Recently_Issued_Accounting_Pro

Recently Issued Accounting Pronouncements	6 Months Ended
	Jun. 29, 2014
Recently Issued Accounting Pronouncements	'
	C. Recently Issued Accounting Pronouncements
	On July 18, 2013, Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2013-11, “Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists.” Under this ASU, unrecognized tax benefits will be netted against all available same-jurisdiction loss or other tax carryforwards that would be utilized, rather than only against carryforwards that are created by unrecognized tax benefits. The provisions of this ASU are effective for interim and annual periods beginning on or after December 15, 2013. Teradyne’s implementation of this ASU did not have a material impact on Teradyne’s financial position and results of operations.
	In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606)” which will replace numerous requirements in U.S. GAAP, including industry-specific requirements, and provide companies with a single revenue recognition model for recognizing revenue from contracts with customers. The core principle of the new standard is that a company should recognize revenue to show the transfer of promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard will be effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. For Teradyne, the standard will be effective in the first quarter of 2017. The two permitted transition methods under the new standard are the full retrospective method, in which case the standard would be applied to each prior reporting period presented, or the modified retrospective method, in which case the cumulative effect of applying the standard would be recognized at the date of initial application. Teradyne has not yet selected a transition method. Teradyne is currently evaluating the impact of this ASU on its financial position and results of operations.

Financial_Instruments_and_Deri

Financial Instruments and Derivatives	6 Months Ended
	Jun. 29, 2014
Financial Instruments and Derivatives	'
	D. Financial Instruments and Derivatives
	Cash Equivalents
	Teradyne considers all highly liquid investments with maturities of three months or less at the date of acquisition to be cash equivalents.
	Financial Instruments
	Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, “Investments—Debt and Equity Securities.” ASC 320-10 requires that certain debt and equity securities be classified into one of three categories; trading, available-for-sale or held-to-maturity securities. As of June 29, 2014, Teradyne’s investments in debt and equity securities were classified as available-for-sale and recorded at their fair market value.
	On a quarterly basis, Teradyne reviews its investments to identify and evaluate those that have an indication of a potential other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include:
		•		The length of time and the extent to which the market value has been less than cost;
		•		The financial condition and near-term prospects of the issuer; and
		•		The intent and ability to retain the investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value.
	Teradyne uses the market and income approach techniques to value its financial instruments and there were no changes in valuation techniques during the three and six months ended June 29, 2014 and June 30, 2013. As defined in ASC 820-10 “Fair Value Measurements and Disclosures”, fair value is the price that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. ASC 820-10 requires that assets and liabilities carried at fair value be classified and disclosed in one of the following three categories:
	Level 1: Quoted prices in active markets for identical assets as of the reporting date.
	Level 2: Inputs other than Level 1, that are observable either directly or indirectly as of the reporting date. For example, a common approach for valuing fixed income securities is the use of matrix pricing, a technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3: Unobservable inputs that are not supported by market data. Unobservable inputs are developed based on the best information available, which might include Teradyne’s own data.
	Substantially all of Teradyne’s fixed income securities are classified as Level 2, with the exception of investments in equity and debt mutual funds, which are classified as Level 1, and contingent consideration, which is classified as Level 3. The majority of Teradyne’s Level 2 securities are priced by pricing vendors. These pricing vendors utilize the most recent observable market information in pricing these securities or, if specific prices are not available, use other observable inputs like market transactions involving identical or comparable securities.
	During the six months ended June 29, 2014 and June 30, 2013, there were no transfers in or out of Level 1, Level 2 or Level 3 financial instruments.
	There were no realized losses recorded in the three and six months ended June 29, 2014 and June 30, 2013. Realized gains recorded in the three and six months ended June 29, 2014 were $0.4 million and $0.7 million, respectively. Realized gains recorded in the three and six months ended June 30, 2013 were $0.1 million and $0.3 million, respectively. Realized gains are included in interest income.
	The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of June 29, 2014 and December 31, 2013.
			June 29, 2014
			Quoted Prices				Significant				Significant			Total
			in Active				Other				Unobservable
			Markets for				Observable				Inputs
			Identical				Inputs				(Level 3)
			Instruments				(Level 2)
			(Level 1)
			(in thousands)
	Assets
	Cash		$	136,730			$	—			$	—		$	136,730
	Cash equivalents			112,152				5,743				—			117,895
	Available-for-sale securities:
	U.S. Treasury securities			—				404,942				—			404,942
	U.S. government agency securities			—				228,075				—			228,075
	Commercial paper			—				108,459				—			108,459
	Corporate debt securities			—				82,490				—			82,490
	Equity and debt mutual funds			14,441				—				—			14,441
	Certificates of deposit and time deposits			—				14,030				—			14,030
	Non-U.S. government securities			—				79				—			79
	Total		$	263,323			$	843,818			$	—		$	1,107,141
	Liabilities
	Contingent consideration		$	—			$	—			$	2,230		$	2,230
	Derivatives			—				306				—			306
	Total		$	—			$	306			$	2,230		$	2,536
	Reported as follows:
			(Level 1)				(Level 2)				(Level 3)			Total
			(in thousands)
	Assets
	Cash and cash equivalents		$	248,882			$	5,743			$	—		$	254,625
	Marketable securities			—				488,439				—			488,439
	Long-term marketable securities			14,441				349,636				—			364,077
			$	263,323			$	843,818			$	—		$	1,107,141
	Liabilities
	Other accrued liabilities		$	—			$	306			$	—		$	306
	Long-term other accrued liabilities			—				—				2,230			2,230
			$	—			$	306			$	2,230		$	2,536
			December 31, 2013
			Quoted Prices				Significant				Significant			Total
			in Active				Other				Unobservable
			Markets for				Observable				Inputs
			Identical				Inputs				(Level 3)
			Instruments				(Level 2)
			(Level 1)
			(in thousands)
	Assets
	Cash		$	117,242			$	—			$	—		$	117,242
Cash equivalents			165,865				58,531				—			224,396
Available-for-sale securities:
U.S. Treasury securities			—				467,895				—			467,895
U.S. government agency securities			—				202,588				—			202,588
Commercial paper			—				105,598				—			105,598
Corporate debt securities			—				65,387				—			65,387
Equity and debt mutual funds			13,156				—				—			13,156
Certificates of deposit and time deposits			—				3,258				—			3,258
Non-U.S. government securities			—				78				—			78
Total			296,263				903,335				—			1,199,598
Derivatives			—				153				—			153
Total		$	296,263			$	903,488			$	—		$	1,199,751
Liabilities
Contingent consideration		$	—			$	—			$	2,230		$	2,230
Total		$	—			$	—			$	2,230		$	2,230
Reported as follows:
		(Level 1)				(Level 2)				(Level 3)			Total
		(in thousands)
Assets
Cash and cash equivalents		$	283,107			$	58,531			$	—		$	341,638
Marketable securities			—				586,882				—			586,882
Long-term marketable securities			13,156				257,922				—			271,078
Other current assets			—				153				—			153
		$	296,263			$	903,488			$	—		$	1,199,751
Liabilities
Long-term other accrued liabilities		$	—			$	—			$	2,230		$	2,230
		$	—			$	—			$	2,230		$	2,230
Contingent consideration relates to Teradyne’s acquisition of ZTEC on October 25, 2013. The total purchase price included $2.2 million in fair value of contingent consideration payable upon achievement of certain customer order and revenue targets through 2015. The maximum amount of contingent consideration that could be paid is $5.0 million. Based on the projected results for the acquisition, no value was assigned to the revenue component of the contingent consideration.
The valuation of the customer order component of the contingent consideration utilized the following assumptions: (1) probability of meeting each benchmark; (2) expected timing of meeting each benchmark; and (3) discount rate reflecting the risk associated with the expected payments. The probabilities and timing for each benchmark were estimated based on a review of the historical and projected results. A discount rate of 5.2 percent was selected based on the cost of debt for the business, as a significant portion of the risk in achieving the customer order contingent consideration was captured in the probabilities assigned to meeting each benchmark. There were no changes to the fair value of the contingent consideration during the six months ended June 29, 2014.
Changes in the fair value of Level 3 contingent consideration for the three and six months ended June 29, 2014 and June 30, 2013 were as follows:
Contingent consideration related to Teradyne’s acquisition of ZTEC
in October 2013		For the Three and Six Months
		Ended
		June 29, 2014
		(in thousands)
Balance at December 31, 2013		$	2,230
Contingent consideration payments			—
Balance at March 30, 2014			2,230
Contingent consideration payments			—
Balance at June 29, 2014		$	2,230
Contingent consideration related to Teradyne’s acquisition of LitePoint		For the Three and Six Months
in October 2011		Ended
		30-Jun-13
		(in thousands)
Balance at December 31, 2012		$	388
Contingent consideration payments			(313	)
Balance at March 31, 2013			75
Contingent consideration payments			(75	)
Balance at June 30, 2013		$	—
The carrying amounts and fair values of Teradyne’s financial instruments at June 29, 2014 and December 31, 2013 were as follows:
		June 29, 2014								December 31, 2013
		Carrying Value				Fair Value				Carrying Value			Fair Value
		(in thousands)
Cash and cash equivalents		$	254,625			$	254,625			$	341,638		$	341,638
Marketable securities			852,516				852,516				857,960			857,960
Convertible debt(1)			—				—				185,708			611,433
Japan loan			—				—				955			955
-1	The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion feature.
The fair values of cash and cash equivalents, accounts receivable, net and accounts payable approximate the carrying amount due to the short-term nature of these instruments.
The following tables summarize the composition of available-for-sale marketable securities at June 29, 2014 and December 31, 2013:
		June 29, 2014
		Available-for-Sale														Fair Market
																Value of
																Investments
																with Unrealized
		Cost				Unrealized				Unrealized			Fair Market			Losses
						Gain				(Loss)			Value
		(in thousands)
U.S. Treasury securities		$	404,707			$	308			$	(73	)	$	404,942		$	36,402
U.S. government agency securities			227,889				202				(16	)		228,075			41,122
Commercial paper			108,446				13				—			108,459			—
Corporate debt securities			80,771				1,903				(184	)		82,490			25,959
Equity and debt mutual funds			11,567				2,898				(24	)		14,441			839
Certificates of deposit and time deposits			14,027				3				—			14,030			—
Non-U.S. government securities			79				—				—			79			—
		$	847,486			$	5,327			$	(297	)	$	852,516		$	104,322
Reported as follows:
		Cost				Unrealized				Unrealized			Fair Market			Fair Market
						Gain				(Loss)			Value			Value of
																Investments
																with Unrealized
																Losses
		(in thousands)
Marketable securities		$	488,257			$	186			$	(4	)	$	488,439		$	26,407
Long-term marketable securities			359,229				5,141				(293	)		364,077			77,915
		$	847,486			$	5,327			$	(297	)	$	852,516		$	104,322
		December 31, 2013
		Available-for-Sale														Fair Market
																Value of
																Investments
																with Unrealized
		Cost				Unrealized				Unrealized			Fair Market			Losses
						Gain				(Loss)			Value
		(in thousands)
U.S. Treasury securities		$	468,084			$	94			$	(283	)	$	467,895		$	108,212
U.S. government agency securities			202,573				75				(60	)		202,588			84,498
Commercial paper			105,583				16				(1	)		105,598			7,993
Corporate debt securities			65,747				762				(1,122	)		65,387			40,355
Equity and debt mutual funds			10,463				2,742				(49	)		13,156			702
Certificates of deposit and time deposits			3,258				—				—			3,258			—
Non-U.S. government securities			78				—				—			78			—
		$	855,786			$	3,689			$	(1,515	)	$	857,960		$	241,760
Reported as follows:
		Cost				Unrealized				Unrealized			Fair Market			Fair Market
						Gain				(Loss)			Value			Value of
																Investments
																with Unrealized
																Losses
		(in thousands)
Marketable securities		$	586,818			$	85			$	(21	)	$	586,882		$	137,670
Long-term marketable securities			268,968				3,604				(1,494	)		271,078			104,090
		$	855,786			$	3,689			$	(1,515	)	$	857,960		$	241,760
As of June 29, 2014, the fair market value of investments with unrealized losses was $104.3 million. Of this value, $6.9 million had unrealized losses greater than one year and $97.4 million had unrealized losses less than one year. As of December 31, 2013, the fair market value of investments with unrealized losses was $241.8 million. Of this value, $0.9 million had unrealized losses greater than one year and $240.9 million had unrealized losses less than one year. Teradyne reviews its investments to identify and evaluate investments that have an indication of possible impairment. Based on this review, Teradyne determined that the unrealized losses related to these investments, at June 29, 2014 and December 31, 2013, were temporary.
The contractual maturities of investments held at June 29, 2014 were as follows:
		June 29, 2014
		Cost				Fair Market
						Value
		(in thousands)
Due within one year		$	488,257			$	488,439
Due after 1 year through 5 years			317,047				317,321
Due after 5 years through 10 years			6,289				6,467
Due after 10 years			24,326				25,848
Total		$	835,919			$	838,075
Contractual maturities of investments held at June 29, 2014 exclude equity and debt mutual funds as they do not have a contractual maturity date.
Derivatives
Teradyne conducts business in a number of foreign countries, with certain transactions denominated in local currencies. The purpose of Teradyne’s foreign currency management is to minimize the effect of exchange rate fluctuations on certain foreign currency denominated monetary assets and liabilities. Teradyne does not use derivative financial instruments for trading or speculative purposes.
To minimize the effect of exchange rate fluctuations associated with the remeasurement of monetary assets and liabilities denominated in foreign currencies, Teradyne enters into foreign currency forward contracts. The change in fair value of these derivatives is recorded directly in earnings, and is used to offset the change in value of the monetary assets and liabilities denominated in foreign currencies.
The notional amount of foreign currency forward contracts was $69.4 million and $74.8 million at June 29, 2014 and December 31, 2013, respectively.
The fair value of the outstanding contracts was a loss of $0.3 million and a gain of $0.2 million at June 29, 2014 and December 31, 2013, respectively. The following table summarizes the fair value of derivative instruments at June 29, 2014 and December 31, 2013:
		Balance Sheet Location		June 29,				December 31,
				2014				2013
				(in thousands)
Derivatives not designated as hedging instruments:
Foreign currency forward contracts		Other current assets		$	—			$	153
		Other accrued liabilities			306				—
				$	306			$	153
Teradyne had no offsetting foreign exchange contracts at June 29, 2014 and December 31, 2013.
In the three and six months ended June 29, 2014, Teradyne recorded net realized losses of $1.1 million and $1.9 million, respectively, related to foreign currency forward contracts hedging net monetary positions. In the three and six months ended June 30, 2013, Teradyne recorded net realized gains of $1.8 million and $4.1 million, respectively, related to foreign currency forward contracts hedging net monetary positions. Gains and losses on foreign currency forward contracts and foreign currency remeasurement gains and losses on monetary assets and liabilities are included in interest expense and other.
The following table summarizes the effect of derivative instruments recognized in the statement of operations during the three and six months ended June 29, 2014 and June 30, 2013. The table does not reflect the corresponding gains (losses) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies. For the three and six months ended June 29, 2014, gains from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $0.7 million and $1.3 million, respectively. For the three and six months ended June 30, 2013, (losses) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $(1.8) million and $(4.6) million, respectively.
		Location of Gains				For the Three Months							For the Six
		(Losses)				Ended							Months
		Recognized in											Ended
		Statement
		of Operations				June 29,				June 30,			June 29,			June 30,
						2014				2013			2014			2013
						(in thousands)
Derivatives not designated as hedging instruments:
Foreign exchange contracts			Interest expense and other			$	(1,122	)		$	1,818		$	(1,869	)	$	4,067
						$	(1,122	)		$	1,818		$	(1,869	)	$	4,067
See Note E: “Debt” regarding derivatives related to convertible senior notes.

Debt

Debt	6 Months Ended
	Jun. 29, 2014
Debt	'
	E. Debt
	Loan Agreement
	On March 31, 2009, Teradyne K.K., Teradyne’s wholly-owned subsidiary in Japan, entered into a loan agreement with a local bank in Japan to borrow approximately $10.0 million (the loan was denominated in Japanese Yen). The loan had a term of 5 years and a fixed interest rate of 0.8%. Approximately $6.0 million of the loan was collateralized by a real estate mortgage on Teradyne K.K.’s building and land in Kumamoto, Japan and approximately $4.0 million was unsecured. Teradyne, Inc. guaranteed payment of the loan obligation. The loan was amortized over the term of the loan with semiannual principal payments of approximately $1.0 million on September 30 and March 30 each year. The final principal and interest payments were made in March 2014.
	Convertible Senior Notes
	In April 2009, Teradyne issued 4.50% convertible senior notes (the “Notes”) at an aggregate principal amount of $190 million and a conversion price of $5.4750 or 182.65 shares of Teradyne’s common stock per $1,000 principal amount of Notes. The Notes had a maturity date of March 15, 2014. Substantially all of the Notes were converted prior to March 15, 2014 and were “net share settled,” meaning that the holders received, for each $1,000 in principal amount of Notes, $1,000 in cash and approximately 131.95 shares of Teradyne common stock (calculated by taking 182.65 shares less 50.7 shares). The 50.7 shares were determined by dividing the $1,000 principal amount by the $19.74 average trading price of Teradyne’s common stock over the 25 day trading period from February 5, 2014 to March 12, 2014.
	Teradyne satisfied the Notes “net share settlement” by paying the aggregate principal amount of $190 million in cash and issuing 25.1 million shares of common stock. On March 13, 2014, Teradyne exercised its call option agreement entered into with Goldman, Sachs & Co. (the “hedge counterparty”) at the time of issuance of the Notes and received 25.1 million shares of Teradyne’s common stock, which were retired.
	Subsequently, the hedge counterparty can exercise warrants with a strike price of $7.6389. The warrants are net share settled. Approximately 536,000 warrants expire on a daily basis over a 65-day trading period from June 17, 2014 to September 17, 2014. In the three months ended June 29, 2014, approximately 1.9 million shares were issued for warrants exercised.
	The tables below represent the components of Teradyne’s convertible senior notes:
		June 29,		December 31,
		2014		2013
		(in thousands)
	Debt principal	$	—	$	189,998
	Unamortized debt discount		—		4,290
	Net carrying amount of the convertible debt	$	—	$	185,708
	The interest expense on Teradyne’s convertible senior notes for the three and six months ended June 29, 2014 and June 30, 2013 was as follows:
		For the Three Months				For the Six Months
		Ended				Ended
		June 29,		June 30,		June 29,		June 30,
		2014		2013		2014		2013
		(in thousands)
	Contractual interest expense	$	—	$	2,137	$	1,757	$	4,274
	Amortization of the discount component and debt issue fees		—		4,087		4,493		8,044
	Total interest expense on the convertible debt	$	—	$	6,224	$	6,250	$	12,318

Prepayments

Prepayments	6 Months Ended
	Jun. 29, 2014
Prepayments	'
	F. Prepayments
	Prepayments consist of the following and are included in prepayments on the balance sheet:
		June 29,		December 31,
		2014		2013
		(in thousands)
	Contract manufacturer prepayments	$	92,196	$	115,388
	Prepaid maintenance and other services		6,838		6,538
	Prepaid taxes		1,960		3,281
	Other prepayments		9,479		11,167
	Total prepayments	$	110,473	$	136,374

Deferred_Revenue_and_Customer_

Deferred Revenue and Customer Advances	6 Months Ended
	Jun. 29, 2014
Deferred Revenue and Customer Advances	'
	G. Deferred Revenue and Customer Advances
	Deferred revenue and customer advances consist of the following and are included in short and long-term deferred revenue and customer advances on the balance sheet:
		June 29,		December 31,
		2014		2013
		(in thousands)
	Extended warranty	$	40,052	$	34,909
	Equipment maintenance and training		26,535		22,455
	Customer advances		8,926		4,825
	Undelivered elements		5,831		6,971
	Customer acceptance		1,616		—
	Total deferred revenue and customer advances	$	82,960	$	69,160

Product_Warranty

Product Warranty	6 Months Ended
	Jun. 29, 2014
Product Warranty	'
	H. Product Warranty
	Teradyne generally provides a one-year warranty on its products, commencing upon installation or shipment. A provision is recorded upon revenue recognition to cost of revenues for estimated warranty expense based on historical experience. Related costs are charged to the warranty accrual as incurred. The warranty balance below is included in other accrued liabilities on the balance sheet.
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Balance at beginning of period	$	6,615		$	7,075		$	6,660		$	9,786
	Accruals for warranties issued during the period		5,399			3,684			8,257			5,107
	Adjustments related to pre-existing warranties		(302	)		(869	)		(442	)		(1,798	)
	Settlements made during the period		(2,639	)		(2,539	)		(5,402	)		(5,744	)
	Balance at end of period	$	9,073		$	7,351		$	9,073		$	7,351
	When Teradyne receives revenue for extended warranty beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The extended warranty balance below is included in short and long-term deferred revenue and customer advances on the balance sheet.
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Balance at beginning of period	$	33,949		$	28,599		$	34,909		$	26,987
	Deferral of new extended warranty revenue		11,960			8,734			14,321			12,205
	Recognition of extended warranty deferred revenue		(5,857	)		(2,479	)		(9,178	)		(4,338	)
	Balance at end of period	$	40,052		$	34,854		$	40,052		$	34,854

StockBased_Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 29, 2014
Stock-Based Compensation	'
	I. Stock-Based Compensation
	In January 2014, Teradyne granted performance-based restricted stock units (“PRSUs”) to its executive officers with a performance metric based on relative total shareholder return (“TSR”). Teradyne’s three-year TSR performance will be measured against the Philadelphia Semiconductor Index, which consists of thirty companies in the semiconductor device and capital equipment industries. The final number of TSR PRSUs that vest will vary based upon the level of performance achieved from 200% of the target shares to 0% of the target shares. All TSR PRSUs will vest upon the three-year anniversary of the January 24, 2014 grant date. No TSR PRSUs will vest if the executive officer is no longer an employee at the end of the three-year period. The TSR PRSUs are valued using a Monte Carlo simulation model. The number of units expected to be earned, based upon the achievement of the TSR market condition, is factored into the grant date Monte Carlo valuation. Compensation expense is recognized on a straight-line basis over the three-year service period. Compensation expense is recognized regardless of the eventual number of units that are earned based upon the market condition, provided the executive officer remains an employee at the end of the three-year period. Compensation expense is reversed if the executive officer is not an employee at the end of the three-year service period. During the six months ended June 29, 2014, Teradyne granted 0.1 million TSR performance-based restricted stock unit awards with a grant date fair value of $22.06. The fair value was estimated using the Monte Carlo simulation model with the following assumptions:
		For the Six Months
		Ended
		June 29,
		2014
	Risk-free interest rate		0.75	%
	Teradyne volatility-historical		36.1	%
	Philadelphia Semiconductor Index volatility-historical		24.6	%
	Dividend yield		1.25	%
	Expected volatility was based on the historical volatility of Teradyne’s stock and the Philadelphia Semiconductor Index over the most recent three year period. The risk-free interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield was based upon an estimated annual dividend amount of $0.24 per share divided by Teradyne’s January 24, 2014 stock price of $19.16.
	During the six months ended June 29, 2014, Teradyne granted 1.6 million of service-based restricted stock unit awards to employees at a weighted average grant date fair value of $19.08 and 0.1 million of service-based stock options to executive officers at a weighted average grant date fair value of $5.49.
	During the six months ended June 30, 2013, Teradyne granted 1.9 million of service-based restricted stock unit awards to employees at a weighted average grant date fair value of $16.60 and 0.2 million of service-based stock options to executive officers at a weighted average grant date fair value of $6.09.
	Restricted stock unit awards granted to employees vest in equal annual installments over four years. Stock options vest in equal annual installments over four years, and have a term of seven years from the date of grant.
	The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions:
		For the Six Months
		Ended
		June 29,			June 30,
		2014			2013
	Expected life (years)		4			4
	Risk-free interest rate		1.2	%		0.6	%
	Volatility-historical		38.8	%		46.8	%
	Dividend yield		1.25	%		0	%
	Teradyne determined the stock options’ expected life based upon historical exercise data for executive officers, the age of the executive officers and the terms of the stock option grant. Volatility was determined using historical volatility for a period equal to the expected life. The risk-free interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield was based upon an estimated annual dividend amount of $0.24 per share divided by Teradyne’s January 24, 2014 stock price of $19.16.
	Effective January 31, 2014, Michael Bradley retired as Chief Executive Officer of Teradyne. Mr. Bradley will continue to serve on Teradyne’s Board of Directors. On January 22, 2014, Teradyne entered into an agreement (the “Retirement Agreement”) with Mr. Bradley. Under the Retirement Agreement, Mr. Bradley’s unvested restricted stock units and stock options granted prior to his retirement date will continue to vest in accordance with their terms through January 31, 2017; and any vested options or options that vest during that period may be exercised for the remainder of the applicable option term. In the Retirement Agreement, Mr. Bradley agreed to be bound by non-competition and non-solicitation restrictions through January 31, 2017. In January 2014, Teradyne recorded a one-time charge to stock-based compensation expense of $6.6 million related to the Retirement Agreement.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 29, 2014
Accumulated Other Comprehensive Income	'
	J. Accumulated Other Comprehensive Income
	Changes in accumulated other comprehensive income, which is presented net of tax, consist of the following:
			Unrealized			Retirement			Total
			Gains on			Plans Prior
			Marketable			Service
			Securities			Credit
			(in thousands)
	Balance at December 31, 2013, net of tax of $794, $(284)		$	1,381		$	2,619		$	4,000
	Other comprehensive income before reclassifications, net of tax of $1,242, $0			2,304			—			2,304
	Amounts reclassified from accumulated other comprehensive income, net of tax of $(243), $(85)			(448	)		(147	)		(595	)
	Net current period other comprehensive income			1,856			(147	)		1,709
	Balance at June 29, 2014, net of tax of $1,793, $(369)		$	3,237		$	2,472		$	5,709
	Reclassifications out of accumulated other comprehensive income to the statement of operations for the three and six months ended June 29, 2014 and June 30, 2013, were as follows:
	Details about Accumulated Other Comprehensive Income		For the Three						For the Six					Affected Line Item
	Components		Months						Months					in the Statements
			Ended						Ended					of Operations
			June 29,			June 30,			June 29,			June 30,
			2014			2013			2014			2013
						(in thousands)
	Available-for-sale marketable securities:
	Unrealized gains, net of tax of $141, $39, $243, $122		$	272		$	68		$	448		$	212	Interest income
	Amortization of defined benefit pension and postretirement plans:
	Prior service benefit, net of tax of $42, $40, $85, $79			74			69			147			138	(a)
	Total reclassifications		$	346		$	137		$	595		$	350	Net income
	(a)	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: “Retirement Plans.”

Intangible_Assets

Intangible Assets	6 Months Ended
	Jun. 29, 2014
Intangible Assets	'
	K. Intangible Assets
	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet:
		June 29, 2014
		Gross		Accumulated		Net		Weighted
		Carrying		Amortization		Carrying		Average
		Amount				Amount		Useful Life
		(in thousands)
	Developed technology	$	342,933	$	200,154	$	142,779		6.2 years
	Customer relationships		141,497		86,145		55,352		8.0 years
	Trade names and trademarks		30,034		12,417		17,617		9.1 years
	Customer backlog		1,000		1,000		—		0.4 years
	Total intangible assets	$	515,464	$	299,716	$	215,748		6.9 years
		December 31, 2013
		Gross		Accumulated		Net		Weighted
		Carrying		Amortization		Carrying		Average
		Amount				Amount		Useful Life
		(in thousands)
	Developed technology	$	342,933	$	174,563	$	168,370		6.2 years
	Customer relationships		141,497		76,963		64,534		8.0 years
	Trade names and trademarks		30,034		10,647		19,387		9.1 years
	Customer backlog		1,000		1,000		—		0.4 years
	Total intangible assets	$	515,464	$	263,173	$	252,291		6.9 years
	Aggregate intangible asset amortization expense was $18.3 million and $36.5 million, respectively, for the three and six months ended June 29, 2014 and $18.1 million and $36.1 million, respectively, for the three and six months ended June 30, 2013. Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows:
	Year	Amortization Expense
		(in thousands)
	2014 (remainder)	$	33,598
	2015		53,391
	2016		53,391
	2017		47,232
	2018		22,691

Net_Income_per_Common_Share

Net Income per Common Share	6 Months Ended
	Jun. 29, 2014
Net Income per Common Share	'
	L. Net Income per Common Share
	The following table sets forth the computation of basic and diluted net income per common share:
			For the Three Months				For the Six Months
			Ended				Ended
			June 29,		June 30,		June 29,		June 30,
			2014		2013		2014		2013
			(in thousands, except per share amounts)
	Net income for basic and diluted net income per share		$	101,205	$	66,556	$	102,134	$	73,145
	Weighted average common shares-basic			194,408		190,569		193,860		190,128
	Effect of dilutive potential common shares:
	Incremental shares from assumed conversion of convertible notes (1)			—		23,266		10,026		23,326
	Convertible note hedge warrant shares (2)			20,406		18,689		20,674		18,774
	Restricted stock units			705		772		878		947
	Stock options			1,006		1,554		1,056		1,615
	Employee stock purchase rights			43		59		32		43
	Dilutive potential common shares			22,160		44,340		32,666		44,705
	Weighted average common shares-diluted			216,568		234,909		226,526		234,833
	Net income per common share-basic		$	0.52	$	0.35	$	0.53	$	0.38
	Net income per common share-diluted		$	0.47	$	0.28	$	0.45	$	0.31
	-1	Incremental shares from conversion of the convertible notes for the six months ended June 29, 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 six months ended June 29, 2014. Incremental shares from assumed conversion of the convertible notes for the three and six months ended June 30, 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 and six months ended June 29, 2014 and June 30, 2013 are calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.6389, multiplied by the weighted average warrant shares outstanding. The result of this calculation, representing the total intrinsic value of the warrant, is divided by the average Teradyne stock price for the period.
	The computation of diluted net income per common share for the three and six months ended June 29, 2014 excludes the effect of the potential exercise of stock options to purchase approximately 0.3 million shares because the effect would have been anti-dilutive.
	The computation of diluted net income per common share for the three and six months ended June 30, 2013 excludes the effect of the potential exercise of stock options to purchase approximately 0.5 million shares because the effect would have been anti-dilutive.

Restructuring_and_Other

Restructuring and Other	6 Months Ended
	Jun. 29, 2014
Restructuring and Other	'
	M. Restructuring and Other
	Restructuring
	During the six months ended June 29, 2014, Teradyne recorded $0.6 million of severance charges related to headcount reductions of 28 people, primarily in Wireless Test. During the six months ended June 30, 2013, Teradyne recorded $0.6 million of severance charges related to headcount reductions in System Test and Semiconductor Test.
		Severance			Facility			Total
		and			Exit
		Benefits			Costs
		(in thousands)
	Pre-2013 Activities
	Balance at December 31, 2012	$	243		$	1,084		$	1,327
	Change in estimate		—			(553	)		(553	)
	Cash payments		(243	)		(531	)		(774	)
	Balance at December 31, 2013	$	—		$	—		$	—
	2013 Activities
	Q3 2013 Activity:
	Provision	$	1,337		$	—		$	1,337
	Cash payments		(966	)		—			(966	)
	Balance at December 31, 2013		371			—			371
	Cash payments		(161	)		—			(161	)
	Balance at March 30, 2014		210			—			210
	Cash payments		—			—			—
	Balance at June 29, 2014	$	210		$	—		$	210
	Q4 2013 Activity:
	Provision	$	600		$	—		$	600
	Cash payments		(486	)		—			(486	)
	Balance at December 31, 2013		114			—			114
	Cash payments		(114	)		—			(114	)
	Balance at March 30, 2014	$	—		$	—		$	—
	2014 Activities
	Q2 2014 Activity:
	Provision	$	572		$	—		$	572
	Cash payments		(530	)		—			(530	)
	Balance at June 29, 2014	$	42		$	—		$	42
	Balance at June 29, 2014	$	252		$	—		$	252
	The accrual balance for severance and benefits of $0.3 million is reflected in the accrued employees’ compensation and withholdings on the balance sheet and is expected to be paid by September 2014.

Retirement_Plans

Retirement Plans	6 Months Ended
	Jun. 29, 2014
Retirement Plans	'
	N. Retirement Plans
	ASC 715, “Compensation—Retirement Benefits” requires an employer with defined benefit plans or other postretirement benefit plans to recognize an asset or a liability on its balance sheet for the overfunded or underfunded status of the plans as defined by ASC 715. The pension asset or liability represents a difference between the fair value of the pension plan’s assets and the projected benefit obligation.
	Defined Benefit Pension Plans
	Teradyne has defined benefit pension plans covering a portion of domestic employees and employees of certain non-U.S. subsidiaries. Benefits under these plans are based on employees’ years of service and compensation. Teradyne’s funding policy is to make contributions to these plans in accordance with local laws and to the extent that such contributions are tax deductible. The assets of these plans consist primarily of fixed income and equity securities. In addition, Teradyne has an unfunded supplemental executive defined benefit plan in the United States to provide retirement benefits in excess of levels allowed by the Employment Retirement Income Security Act (“ERISA”) and the Internal Revenue Code (“IRC”), as well as unfunded foreign plans. In the six months ended June 29, 2014, Teradyne contributed $0.9 million to the U.S. supplemental executive defined benefit pension plan and $1.0 million to certain qualified plans for non-U.S. subsidiaries.
	For the three and six months ended June 29, 2014 and June 30, 2013, Teradyne’s net periodic pension cost was comprised of the following:
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Service cost	$	811		$	852		$	1,607		$	1,686
	Interest cost		3,732			3,281			7,452			6,651
	Expected return on plan assets		(3,384	)		(3,631	)		(6,725	)		(7,261	)
	Amortization of unrecognized prior service cost		34			41			67			82
	Actuarial loss (gain)		362			(1,123	)		362			(1,123	)
	Total net periodic pension cost (benefit)	$	1,555		$	(580	)	$	2,763		$	35
	Postretirement Benefit Plan
	In addition to receiving pension benefits, U.S. Teradyne employees who meet early retirement eligibility requirements as of their termination dates may participate in Teradyne’s Welfare Plan, which includes death, and medical and dental benefits up to age 65. Death benefits provide a fixed sum to retirees’ survivors and are available to all retirees. Substantially all of Teradyne’s current U.S. employees could become eligible for these benefits, and the existing benefit obligation relates primarily to those employees.
	For the three and six months ended June 29, 2014 and June 30, 2013, Teradyne’s net periodic postretirement benefit was comprised of the following:
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Service cost	$	17		$	21		$	29		$	37
	Interest cost		82			84			168			171
	Amortization of unrecognized prior service benefit		(150	)		(150	)		(299	)		(299	)
	Actuarial gain		(247	)		(236	)		(247	)		(236	)
	Total net periodic post-retirement benefit	$	(298	)	$	(281	)	$	(349	)	$	(327	)

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 29, 2014
Commitments and Contingencies	'
	O. Commitments and Contingencies
	Purchase Commitments
	As of June 29, 2014, Teradyne had entered into purchase commitments for certain components and materials. The purchase commitments covered by the agreements aggregate to approximately $222.5 million, of which $211.5 million is for less than one year.
	Legal Claims
	Teradyne is subject to various legal proceedings and claims which have arisen in the ordinary course of business. In the opinion of management, the ultimate disposition of these matters will not have a material adverse effect on Teradyne’s results of operations, financial condition or cash flows.

Income_Taxes

Income Taxes	6 Months Ended
	Jun. 29, 2014
Income Taxes	'
	P. Income Taxes
	The effective tax rate for the three months ended June 29, 2014 and June 30, 2013 was 17%. The effective tax rate for the six months ended June 29, 2014 and June 30, 2013 was 15% and 7%, respectively. The increase in the tax rate for the six months ended June 29, 2014 compared to the six months ended June 30, 2013 was primarily because income tax expense for the six months ended June 30, 2013 was reduced for a discrete tax benefit from the January 2013 reinstatement of the U.S. research and development credit for fiscal year 2012.
	The effective tax rate for each of these periods is lower than the 35% U.S. statutory federal tax rate primarily due to the geographic mix of income and profits earned by Teradyne’s international subsidiaries being taxed at rates lower than the U.S. statutory rate.
	Teradyne qualifies for a tax holiday in Singapore by fulfilling the requirements of an agreement with the Singapore Economic Development Board under which certain headcount and spending requirements must be met. The tax savings due to the tax holiday for the six months ended June 29, 2014 were $6.1 million or $0.03 per diluted share. The tax holiday is currently expected to expire on December 31, 2015.

Segment_Information

Segment Information	6 Months Ended
	Jun. 29, 2014
Segment Information	'
	Q. Segment Information
	Teradyne has three operating segments (Semiconductor Test, Wireless Test and System Test), which are its reportable segments. The Semiconductor Test segment includes operations related to the design, manufacturing and marketing of semiconductor test products and services. The Wireless Test segment includes operations related to design, manufacturing and marketing of wireless test products and services. The System Test segment includes operations related to design, manufacturing and marketing of products and services for military/aerospace instrumentation test, storage test and circuit-board test. Each operating segment has a segment manager who is directly accountable to and maintains regular contact with Teradyne’s chief operating decision maker (Teradyne’s chief executive officer) to discuss operating activities, financial results, forecasts, and plans for the segment.
	Teradyne evaluates performance based on several factors, of which the primary financial measure is business segment income before income taxes. The accounting policies of the business segments are the same as those described in Note B: “Accounting Policies” in Teradyne’s Annual Report on Form 10-K for the year ended December 31, 2013. Segment information is as follows:
			Semiconductor		Wireless			System			Corporate			Consolidated
			Test		Test			Test			and
											Eliminations
			(in thousands)
	Three months ended June 29, 2014:
	Net revenues		$	421,434	$	68,699		$	35,434		$	—		$	525,567
	Income (loss) before income taxes(1)(2)			107,270		14,229			(715	)		608			121,392
	Three months ended June 30, 2013:
	Net revenues		$	292,431	$	99,386		$	37,072		$	—		$	428,889
	Income (loss) before income taxes(1)(2)			58,606		23,913			779			(2,941	)		80,357
	Six months ended June 29, 2014:
	Net revenues		$	683,171	$	89,909		$	73,497		$	—		$	846,577
	Income (loss) before income taxes(1)(2)			141,870		(10,856	)		(267	)		(11,228	)		119,519
	Six months ended June 30, 2013:
	Net revenues		$	503,937	$	132,984		$	72,335		$	—		$	709,256
	Income (loss) before income taxes(1)(2)			72,372		13,916			2,309			(9,666	)		78,931
	-1	Pension and postretirement actuarial gains and losses, interest income, and interest expense and other are included in Corporate and Eliminations.
	-2	Included in the income (loss) before income taxes for each of the segments are charges and credits for the three and six months ended June 29, 2014 and June 30, 2013 that include restructuring and other, and provision for excess and obsolete inventory, as follows:
	Included in the Semiconductor Test segment are charges for the following:
			For the Three Months					For the Six Months
			Ended					Ended
			June 29,		June 30,			June 29,			June 30,
			2014		2013			2014			2013
			(in thousands)
	Cost of revenues—provision for excess and obsolete inventory		$	3,713	$	287		$	9,918		$	500
	Total		$	3,713	$	287		$	9,918		$	500
	Included in the Wireless Test segment are charges for the following:
			For the Three Months					For the Six Months
			Ended					Ended
			June 29,		June 30,			June 29,			June 30,
			2014		2013			2014			2013
			(in thousands)
	Cost of revenues—provision for excess and obsolete inventory		$	879	$	1,398		$	3,972		$	4,066
	Restructuring and other			426		—			426			—
	Total		$	1,305	$	1,398		$	4,398		$	4,066
	Included in the System Test segment are charges for the following:
			For the Three Months					For the Six Months
			Ended					Ended
			June 29,		June 30,			June 29,			June 30,
			2014		2013			2014			2013
			(in thousands)
	Cost of revenues—provision for excess and obsolete inventory		$	440	$	290		$	1,181		$	1,209
	Restructuring and other			146		131			146			375
	Total		$	586	$	421		$	1,327		$	1,584

Shareholders_Equity

Shareholders' Equity	6 Months Ended
	Jun. 29, 2014
Shareholders' Equity	'
	R. Shareholders’ Equity
	Stock Repurchase Program
	In November 2010, Teradyne’s Board of Directors authorized a stock repurchase program for up to $200 million. In the three and six months ended June 29, 2014 and June 30, 2013, Teradyne did not repurchase any shares. The cumulative repurchases under the new program as of June 29, 2014 totaled 2.6 million shares of common stock for $31.2 million at an average price of $11.84.
	Dividend
	In January 2014, Teradyne’s Board of Directors declared an initial quarterly cash dividend of $0.06 per share that was paid on June 2, 2014 to stockholders of record as of May 9, 2014. The total dividend payment was $11.7 million. Payment of future cash dividends will rest within the discretion of Teradyne’s Board of Directors and will depend, among other things, upon Teradyne’s earnings, capital requirements and financial condition.

Accounting_Policies_Policies

Accounting Policies (Policies)	6 Months Ended
	Jun. 29, 2014
Basis of Presentation	'
	Basis of Presentation
	The consolidated interim financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated. These interim financial statements are unaudited and reflect all normal recurring adjustments that are, in the opinion of management, necessary for the fair presentation of such interim financial statements. Certain prior year’s amounts were reclassified to conform to the current year presentation. The December 31, 2013 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.
	The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in Teradyne’s Annual Report on Form 10-K, filed with the U.S. Securities and Exchange Commission (“SEC”) on February 28, 2014, for the year ended December 31, 2013.
Preparation of Financial Statements and Use of Estimates	'
	Preparation of Financial Statements and Use of Estimates
	The preparation of consolidated financial statements requires management to make estimates and judgments that affect the amounts reported in the financial statements. Actual results may differ significantly from these estimates.

Financial_Instruments_and_Deri1

Financial Instruments and Derivatives (Tables)	6 Months Ended
	Jun. 29, 2014
Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	'
	The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of June 29, 2014 and December 31, 2013.
			June 29, 2014
			Quoted Prices				Significant				Significant			Total
			in Active				Other				Unobservable
			Markets for				Observable				Inputs
			Identical				Inputs				(Level 3)
			Instruments				(Level 2)
			(Level 1)
			(in thousands)
	Assets
	Cash		$	136,730			$	—			$	—		$	136,730
	Cash equivalents			112,152				5,743				—			117,895
	Available-for-sale securities:
	U.S. Treasury securities			—				404,942				—			404,942
	U.S. government agency securities			—				228,075				—			228,075
	Commercial paper			—				108,459				—			108,459
	Corporate debt securities			—				82,490				—			82,490
	Equity and debt mutual funds			14,441				—				—			14,441
	Certificates of deposit and time deposits			—				14,030				—			14,030
	Non-U.S. government securities			—				79				—			79
	Total		$	263,323			$	843,818			$	—		$	1,107,141
	Liabilities
	Contingent consideration		$	—			$	—			$	2,230		$	2,230
	Derivatives			—				306				—			306
	Total		$	—			$	306			$	2,230		$	2,536
	Reported as follows:
			(Level 1)				(Level 2)				(Level 3)			Total
			(in thousands)
	Assets
	Cash and cash equivalents		$	248,882			$	5,743			$	—		$	254,625
	Marketable securities			—				488,439				—			488,439
	Long-term marketable securities			14,441				349,636				—			364,077
			$	263,323			$	843,818			$	—		$	1,107,141
	Liabilities
	Other accrued liabilities		$	—			$	306			$	—		$	306
	Long-term other accrued liabilities			—				—				2,230			2,230
			$	—			$	306			$	2,230		$	2,536
			December 31, 2013
			Quoted Prices				Significant				Significant			Total
			in Active				Other				Unobservable
			Markets for				Observable				Inputs
			Identical				Inputs				(Level 3)
			Instruments				(Level 2)
			(Level 1)
			(in thousands)
	Assets
	Cash		$	117,242			$	—			$	—		$	117,242
	Cash equivalents			165,865				58,531				—			224,396
	Available-for-sale securities:
	U.S. Treasury securities			—				467,895				—			467,895
	U.S. government agency securities			—				202,588				—			202,588
	Commercial paper			—				105,598				—			105,598
	Corporate debt securities			—				65,387				—			65,387
	Equity and debt mutual funds			13,156				—				—			13,156
	Certificates of deposit and time deposits			—				3,258				—			3,258
	Non-U.S. government securities			—				78				—			78
	Total			296,263				903,335				—			1,199,598
	Derivatives			—				153				—			153
	Total		$	296,263			$	903,488			$	—		$	1,199,751
	Liabilities
	Contingent consideration		$	—			$	—			$	2,230		$	2,230
	Total		$	—			$	—			$	2,230		$	2,230
	Reported as follows:
		(Level 1)				(Level 2)				(Level 3)			Total
		(in thousands)
Assets
Cash and cash equivalents		$	283,107			$	58,531			$	—		$	341,638
Marketable securities			—				586,882				—			586,882
Long-term marketable securities			13,156				257,922				—			271,078
Other current assets			—				153				—			153
		$	296,263			$	903,488			$	—		$	1,199,751
Liabilities
Long-term other accrued liabilities		$	—			$	—			$	2,230		$	2,230
		$	—			$	—			$	2,230		$	2,230
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	'
	Changes in the fair value of Level 3 contingent consideration for the three and six months ended June 29, 2014 and June 30, 2013 were as follows:
	Contingent consideration related to Teradyne’s acquisition of ZTEC
	in October 2013		For the Three and Six Months
			Ended
			June 29, 2014
			(in thousands)
	Balance at December 31, 2013		$	2,230
	Contingent consideration payments			—
	Balance at March 30, 2014			2,230
	Contingent consideration payments			—
	Balance at June 29, 2014		$	2,230
	Contingent consideration related to Teradyne’s acquisition of LitePoint		For the Three and Six Months
	in October 2011		Ended
			30-Jun-13
			(in thousands)
	Balance at December 31, 2012		$	388
	Contingent consideration payments			(313	)
	Balance at March 31, 2013			75
	Contingent consideration payments			(75	)
	Balance at June 30, 2013		$	—
Schedule of Carrying Amounts and Fair Values of Financial Instruments	'
	The carrying amounts and fair values of Teradyne’s financial instruments at June 29, 2014 and December 31, 2013 were as follows:
			June 29, 2014								December 31, 2013
			Carrying Value				Fair Value				Carrying Value			Fair Value
			(in thousands)
	Cash and cash equivalents		$	254,625			$	254,625			$	341,638		$	341,638
	Marketable securities			852,516				852,516				857,960			857,960
	Convertible debt(1)			—				—				185,708			611,433
	Japan loan			—				—				955			955
	-1	The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion feature.
Schedule of Available-for-Sale Marketable Securities	'
	The following tables summarize the composition of available-for-sale marketable securities at June 29, 2014 and December 31, 2013:
			June 29, 2014
			Available-for-Sale														Fair Market
																	Value of
																	Investments
																	with Unrealized
			Cost				Unrealized				Unrealized			Fair Market			Losses
							Gain				(Loss)			Value
			(in thousands)
	U.S. Treasury securities		$	404,707			$	308			$	(73	)	$	404,942		$	36,402
	U.S. government agency securities			227,889				202				(16	)		228,075			41,122
	Commercial paper			108,446				13				—			108,459			—
	Corporate debt securities			80,771				1,903				(184	)		82,490			25,959
	Equity and debt mutual funds			11,567				2,898				(24	)		14,441			839
	Certificates of deposit and time deposits			14,027				3				—			14,030			—
	Non-U.S. government securities			79				—				—			79			—
			$	847,486			$	5,327			$	(297	)	$	852,516		$	104,322
	Reported as follows:
			Cost				Unrealized				Unrealized			Fair Market			Fair Market
							Gain				(Loss)			Value			Value of
																	Investments
																	with Unrealized
																	Losses
			(in thousands)
	Marketable securities		$	488,257			$	186			$	(4	)	$	488,439		$	26,407
	Long-term marketable securities			359,229				5,141				(293	)		364,077			77,915
			$	847,486			$	5,327			$	(297	)	$	852,516		$	104,322
			December 31, 2013
			Available-for-Sale														Fair Market
																	Value of
																	Investments
																	with Unrealized
			Cost				Unrealized				Unrealized			Fair Market			Losses
							Gain				(Loss)			Value
			(in thousands)
	U.S. Treasury securities		$	468,084			$	94			$	(283	)	$	467,895		$	108,212
	U.S. government agency securities			202,573				75				(60	)		202,588			84,498
	Commercial paper			105,583				16				(1	)		105,598			7,993
	Corporate debt securities			65,747				762				(1,122	)		65,387			40,355
	Equity and debt mutual funds			10,463				2,742				(49	)		13,156			702
	Certificates of deposit and time deposits			3,258				—				—			3,258			—
	Non-U.S. government securities			78				—				—			78			—
			$	855,786			$	3,689			$	(1,515	)	$	857,960		$	241,760
	Reported as follows:
			Cost				Unrealized				Unrealized			Fair Market			Fair Market
							Gain				(Loss)			Value			Value of
																	Investments
																	with Unrealized
																	Losses
			(in thousands)
	Marketable securities		$	586,818			$	85			$	(21	)	$	586,882		$	137,670
	Long-term marketable securities			268,968				3,604				(1,494	)		271,078			104,090
			$	855,786			$	3,689			$	(1,515	)	$	857,960		$	241,760
Contractual Maturities of Investments Held	'
	The contractual maturities of investments held at June 29, 2014 were as follows:
			June 29, 2014
			Cost				Fair Market
							Value
			(in thousands)
	Due within one year		$	488,257			$	488,439
	Due after 1 year through 5 years			317,047				317,321
	Due after 5 years through 10 years			6,289				6,467
	Due after 10 years			24,326				25,848
	Total		$	835,919			$	838,075
Schedule of Derivative Instruments in Statement of Financial Position at Fair Value	'
	The following table summarizes the fair value of derivative instruments at June 29, 2014 and December 31, 2013:
			Balance Sheet Location		June 29,				December 31,
					2014				2013
					(in thousands)
	Derivatives not designated as hedging instruments:
	Foreign currency forward contracts		Other current assets		$	—			$	153
			Other accrued liabilities			306				—
					$	306			$	153
Schedule of Effect of Derivative Instruments on Statement of Operations Recognized	'
	The following table summarizes the effect of derivative instruments recognized in the statement of operations during the three and six months ended June 29, 2014 and June 30, 2013. The table does not reflect the corresponding gains (losses) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies. For the three and six months ended June 29, 2014, gains from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $0.7 million and $1.3 million, respectively. For the three and six months ended June 30, 2013, (losses) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $(1.8) million and $(4.6) million, respectively.
			Location of Gains				For the Three Months							For the Six
			(Losses)				Ended							Months
			Recognized in											Ended
			Statement
			of Operations				June 29,				June 30,			June 29,			June 30,
							2014				2013			2014			2013
							(in thousands)
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts			Interest expense and other			$	(1,122	)		$	1,818		$	(1,869	)	$	4,067
							$	(1,122	)		$	1,818		$	(1,869	)	$	4,067

Debt_Tables

Debt (Tables)	6 Months Ended
	Jun. 29, 2014
Components of Convertible Senior Notes	'
	The tables below represent the components of Teradyne’s convertible senior notes:
		June 29,		December 31,
		2014		2013
		(in thousands)
	Debt principal	$	—	$	189,998
	Unamortized debt discount		—		4,290
	Net carrying amount of the convertible debt	$	—	$	185,708
Interest Expense on Convertible Senior Notes	'
	The interest expense on Teradyne’s convertible senior notes for the three and six months ended June 29, 2014 and June 30, 2013 was as follows:
		For the Three Months				For the Six Months
		Ended				Ended
		June 29,		June 30,		June 29,		June 30,
		2014		2013		2014		2013
		(in thousands)
	Contractual interest expense	$	—	$	2,137	$	1,757	$	4,274
	Amortization of the discount component and debt issue fees		—		4,087		4,493		8,044
	Total interest expense on the convertible debt	$	—	$	6,224	$	6,250	$	12,318

Prepayments_Tables

Prepayments (Tables)	6 Months Ended
	Jun. 29, 2014
Schedule of Prepayments	'
	Prepayments consist of the following and are included in prepayments on the balance sheet:
		June 29,		December 31,
		2014		2013
		(in thousands)
	Contract manufacturer prepayments	$	92,196	$	115,388
	Prepaid maintenance and other services		6,838		6,538
	Prepaid taxes		1,960		3,281
	Other prepayments		9,479		11,167
	Total prepayments	$	110,473	$	136,374

Deferred_Revenue_and_Customer_1

Deferred Revenue and Customer Advances (Tables)	6 Months Ended
	Jun. 29, 2014
Deferred Revenue and Customer Advances	'
	Deferred revenue and customer advances consist of the following and are included in short and long-term deferred revenue and customer advances on the balance sheet:
		June 29,		December 31,
		2014		2013
		(in thousands)
	Extended warranty	$	40,052	$	34,909
	Equipment maintenance and training		26,535		22,455
	Customer advances		8,926		4,825
	Undelivered elements		5,831		6,971
	Customer acceptance		1,616		—
	Total deferred revenue and customer advances	$	82,960	$	69,160

Product_Warranty_Tables

Product Warranty (Tables)	6 Months Ended
	Jun. 29, 2014
Other Accrued Liabilities	'
	The warranty balance below is included in other accrued liabilities on the balance sheet.
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Balance at beginning of period	$	6,615		$	7,075		$	6,660		$	9,786
	Accruals for warranties issued during the period		5,399			3,684			8,257			5,107
	Adjustments related to pre-existing warranties		(302	)		(869	)		(442	)		(1,798	)
	Settlements made during the period		(2,639	)		(2,539	)		(5,402	)		(5,744	)
	Balance at end of period	$	9,073		$	7,351		$	9,073		$	7,351
Extended Product Warranty of Short and Long-Term Deferred Revenue and Customer Advances	'
	The extended warranty balance below is included in short and long-term deferred revenue and customer advances on the balance sheet.
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Balance at beginning of period	$	33,949		$	28,599		$	34,909		$	26,987
	Deferral of new extended warranty revenue		11,960			8,734			14,321			12,205
	Recognition of extended warranty deferred revenue		(5,857	)		(2,479	)		(9,178	)		(4,338	)
	Balance at end of period	$	40,052		$	34,854		$	40,052		$	34,854

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 29, 2014
Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions	'
	$22.06. The fair value was estimated using the Monte Carlo simulation model with the following assumptions:
		For the Six Months
		Ended
		June 29,
		2014
	Risk-free interest rate		0.75	%
	Teradyne volatility-historical		36.1	%
	Philadelphia Semiconductor Index volatility-historical		24.6	%
	Dividend yield		1.25	%
Schedule of Estimated Fair Value of Stock Options Assumptions	'
	The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions:
		For the Six Months
		Ended
		June 29,			June 30,
		2014			2013
	Expected life (years)		4			4
	Risk-free interest rate		1.2	%		0.6	%
	Volatility-historical		38.8	%		46.8	%
	Dividend yield		1.25	%		0	%

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 29, 2014
Changes in Accumulated Other Comprehensive Income	'
	Changes in accumulated other comprehensive income, which is presented net of tax, consist of the following:
			Unrealized			Retirement			Total
			Gains on			Plans Prior
			Marketable			Service
			Securities			Credit
			(in thousands)
	Balance at December 31, 2013, net of tax of $794, $(284)		$	1,381		$	2,619		$	4,000
	Other comprehensive income before reclassifications, net of tax of $1,242, $0			2,304			—			2,304
	Amounts reclassified from accumulated other comprehensive income, net of tax of $(243), $(85)			(448	)		(147	)		(595	)
	Net current period other comprehensive income			1,856			(147	)		1,709
	Balance at June 29, 2014, net of tax of $1,793, $(369)		$	3,237		$	2,472		$	5,709
Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations	'
	Reclassifications out of accumulated other comprehensive income to the statement of operations for the three and six months ended June 29, 2014 and June 30, 2013, were as follows:
	Details about Accumulated Other Comprehensive Income		For the Three						For the Six					Affected Line Item
	Components		Months						Months					in the Statements
			Ended						Ended					of Operations
			June 29,			June 30,			June 29,			June 30,
			2014			2013			2014			2013
						(in thousands)
	Available-for-sale marketable securities:
	Unrealized gains, net of tax of $141, $39, $243, $122		$	272		$	68		$	448		$	212	Interest income
	Amortization of defined benefit pension and postretirement plans:
	Prior service benefit, net of tax of $42, $40, $85, $79			74			69			147			138	(a)
	Total reclassifications		$	346		$	137		$	595		$	350	Net income
	(a)	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: “Retirement Plans.”

Intangible_Assets_Tables

Intangible Assets (Tables)	6 Months Ended
	Jun. 29, 2014
Schedule of Amortizable Intangible Assets	'
	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet:
		June 29, 2014
		Gross		Accumulated		Net		Weighted
		Carrying		Amortization		Carrying		Average
		Amount				Amount		Useful Life
		(in thousands)
	Developed technology	$	342,933	$	200,154	$	142,779		6.2 years
	Customer relationships		141,497		86,145		55,352		8.0 years
	Trade names and trademarks		30,034		12,417		17,617		9.1 years
	Customer backlog		1,000		1,000		—		0.4 years
	Total intangible assets	$	515,464	$	299,716	$	215,748		6.9 years
		December 31, 2013
		Gross		Accumulated		Net		Weighted
		Carrying		Amortization		Carrying		Average
		Amount				Amount		Useful Life
		(in thousands)
	Developed technology	$	342,933	$	174,563	$	168,370		6.2 years
	Customer relationships		141,497		76,963		64,534		8.0 years
	Trade names and trademarks		30,034		10,647		19,387		9.1 years
	Customer backlog		1,000		1,000		—		0.4 years
	Total intangible assets	$	515,464	$	263,173	$	252,291		6.9 years
Schedule of Estimated Intangible Asset Amortization Expense	'
	Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows:
	Year	Amortization Expense
		(in thousands)
	2014 (remainder)	$	33,598
	2015		53,391
	2016		53,391
	2017		47,232
	2018		22,691

Net_Income_per_Common_Share_Ta

Net Income per Common Share (Tables)	6 Months Ended
	Jun. 29, 2014
Computation of Basic and Diluted Net Income Per Common Share	'
	The following table sets forth the computation of basic and diluted net income per common share:
			For the Three Months				For the Six Months
			Ended				Ended
			June 29,		June 30,		June 29,		June 30,
			2014		2013		2014		2013
			(in thousands, except per share amounts)
	Net income for basic and diluted net income per share		$	101,205	$	66,556	$	102,134	$	73,145
	Weighted average common shares-basic			194,408		190,569		193,860		190,128
	Effect of dilutive potential common shares:
	Incremental shares from assumed conversion of convertible notes (1)			—		23,266		10,026		23,326
	Convertible note hedge warrant shares (2)			20,406		18,689		20,674		18,774
	Restricted stock units			705		772		878		947
	Stock options			1,006		1,554		1,056		1,615
	Employee stock purchase rights			43		59		32		43
	Dilutive potential common shares			22,160		44,340		32,666		44,705
	Weighted average common shares-diluted			216,568		234,909		226,526		234,833
	Net income per common share-basic		$	0.52	$	0.35	$	0.53	$	0.38
	Net income per common share-diluted		$	0.47	$	0.28	$	0.45	$	0.31
	-1	Incremental shares from conversion of the convertible notes for the six months ended June 29, 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 six months ended June 29, 2014. Incremental shares from assumed conversion of the convertible notes for the three and six months ended June 30, 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 and six months ended June 29, 2014 and June 30, 2013 are calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.6389, multiplied by the weighted average warrant shares outstanding. The result of this calculation, representing the total intrinsic value of the warrant, is divided by the average Teradyne stock price for the period.

Restructuring_and_Other_Tables

Restructuring and Other (Tables)	6 Months Ended
	Jun. 29, 2014
Restructuring and Other	'
		Severance			Facility			Total
		and			Exit
		Benefits			Costs
		(in thousands)
	Pre-2013 Activities
	Balance at December 31, 2012	$	243		$	1,084		$	1,327
	Change in estimate		—			(553	)		(553	)
	Cash payments		(243	)		(531	)		(774	)
	Balance at December 31, 2013	$	—		$	—		$	—
	2013 Activities
	Q3 2013 Activity:
	Provision	$	1,337		$	—		$	1,337
	Cash payments		(966	)		—			(966	)
	Balance at December 31, 2013		371			—			371
	Cash payments		(161	)		—			(161	)
	Balance at March 30, 2014		210			—			210
	Cash payments		—			—			—
	Balance at June 29, 2014	$	210		$	—		$	210
	Q4 2013 Activity:
	Provision	$	600		$	—		$	600
	Cash payments		(486	)		—			(486	)
	Balance at December 31, 2013		114			—			114
	Cash payments		(114	)		—			(114	)
	Balance at March 30, 2014	$	—		$	—		$	—
	2014 Activities
	Q2 2014 Activity:
	Provision	$	572		$	—		$	572
	Cash payments		(530	)		—			(530	)
	Balance at June 29, 2014	$	42		$	—		$	42
	Balance at June 29, 2014	$	252		$	—		$	252

Retirement_Plans_Tables

Retirement Plans (Tables)	6 Months Ended
	Jun. 29, 2014
Postretirement Benefit Plans	'
Net Periodic Pension and Postretirement Cost (Benefit)	'
	For the three and six months ended June 29, 2014 and June 30, 2013, Teradyne’s net periodic postretirement benefit was comprised of the following:
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Service cost	$	17		$	21		$	29		$	37
	Interest cost		82			84			168			171
	Amortization of unrecognized prior service benefit		(150	)		(150	)		(299	)		(299	)
	Actuarial gain		(247	)		(236	)		(247	)		(236	)
	Total net periodic post-retirement benefit	$	(298	)	$	(281	)	$	(349	)	$	(327	)
Defined Benefit Pension Plans	'
Net Periodic Pension and Postretirement Cost (Benefit)	'
	For the three and six months ended June 29, 2014 and June 30, 2013, Teradyne’s net periodic pension cost was comprised of the following:
		For the Three Months						For the Six Months
		Ended						Ended
		June 29,			June 30,			June 29,			June 30,
		2014			2013			2014			2013
		(in thousands)
	Service cost	$	811		$	852		$	1,607		$	1,686
	Interest cost		3,732			3,281			7,452			6,651
	Expected return on plan assets		(3,384	)		(3,631	)		(6,725	)		(7,261	)
	Amortization of unrecognized prior service cost		34			41			67			82
	Actuarial loss (gain)		362			(1,123	)		362			(1,123	)
	Total net periodic pension cost (benefit)	$	1,555		$	(580	)	$	2,763		$	35

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Jun. 29, 2014
Segment Information	'
	ended December 31, 2013. Segment information is as follows:
			Semiconductor		Wireless			System			Corporate			Consolidated
			Test		Test			Test			and
											Eliminations
			(in thousands)
	Three months ended June 29, 2014:
	Net revenues		$	421,434	$	68,699		$	35,434		$	—		$	525,567
	Income (loss) before income taxes(1)(2)			107,270		14,229			(715	)		608			121,392
	Three months ended June 30, 2013:
	Net revenues		$	292,431	$	99,386		$	37,072		$	—		$	428,889
	Income (loss) before income taxes(1)(2)			58,606		23,913			779			(2,941	)		80,357
	Six months ended June 29, 2014:
	Net revenues		$	683,171	$	89,909		$	73,497		$	—		$	846,577
	Income (loss) before income taxes(1)(2)			141,870		(10,856	)		(267	)		(11,228	)		119,519
	Six months ended June 30, 2013:
	Net revenues		$	503,937	$	132,984		$	72,335		$	—		$	709,256
	Income (loss) before income taxes(1)(2)			72,372		13,916			2,309			(9,666	)		78,931
	-1	Pension and postretirement actuarial gains and losses, interest income, and interest expense and other are included in Corporate and Eliminations.
	-2	Included in the income (loss) before income taxes for each of the segments are charges and credits for the three and six months ended June 29, 2014 and June 30, 2013 that include restructuring and other, and provision for excess and obsolete inventory, as follows:
Semiconductor Test	'
Schedule of Segment Reporting Information by Segment Charges	'
	Included in the Semiconductor Test segment are charges for the following:
			For the Three Months					For the Six Months
			Ended					Ended
			June 29,		June 30,			June 29,			June 30,
			2014		2013			2014			2013
			(in thousands)
	Cost of revenues—provision for excess and obsolete inventory		$	3,713	$	287		$	9,918		$	500
	Total		$	3,713	$	287		$	9,918		$	500
Wireless Test	'
Schedule of Segment Reporting Information by Segment Charges	'
	Included in the Wireless Test segment are charges for the following:
			For the Three Months					For the Six Months
			Ended					Ended
			June 29,		June 30,			June 29,			June 30,
			2014		2013			2014			2013
			(in thousands)
	Cost of revenues—provision for excess and obsolete inventory		$	879	$	1,398		$	3,972		$	4,066
	Restructuring and other			426		—			426			—
	Total		$	1,305	$	1,398		$	4,398		$	4,066
System Test	'
Schedule of Segment Reporting Information by Segment Charges	'
	Included in the System Test segment are charges for the following:
			For the Three Months					For the Six Months
			Ended					Ended
			June 29,		June 30,			June 29,			June 30,
			2014		2013			2014			2013
			(in thousands)
	Cost of revenues—provision for excess and obsolete inventory		$	440	$	290		$	1,181		$	1,209
	Restructuring and other			146		131			146			375
	Total		$	586	$	421		$	1,327		$	1,584

Financial_Instruments_and_Deri2

Financial Instruments and Derivatives - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended					6 Months Ended	12 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013	Dec. 31, 2013	Oct. 25, 2013	Oct. 25, 2013	Jun. 29, 2014	Dec. 31, 2013
						ZTEC Instruments, Inc.	ZTEC Instruments, Inc.	Foreign Currency Forward Contracts	Foreign Currency Forward Contracts
							Maximum
Financial Instruments and Fair Value [Line Items]	'	'	'	'	'	'	'	'	'
Available-for-sale securities, realized gain	$400,000	$100,000	$700,000	$300,000	'	'	'	'	'
Available-for-sale securities, realized losses	0	0	0	0	'	'	'	'	'
Contingent consideration	'	'	'	'	'	2,200,000	5,000,000	'	'
Contingent consideration discount rate	'	'	5.20%	'	'	'	'	'	'
Changes to fair value of contingent consideration	'	'	0	'	'	'	'	'	'
Fair market value of investments with unrealized losses	104,322,000	'	104,322,000	'	241,760,000	'	'	'	'
Fair market value of investments with unrealized losses greater than one year	6,900,000	'	6,900,000	'	900,000	'	'	'	'
Fair market value of investments with unrealized losses less than one year	97,400,000	'	97,400,000	'	240,900,000	'	'	'	'
Notional amount of foreign currency forward contracts	'	'	'	'	'	'	'	69,400,000	74,800,000
Gains (losses) on foreign currency transactions	700,000	-1,800,000	1,300,000	-4,600,000	'	'	'	-300,000	200,000
Offsetting foreign exchange contracts	0	'	0	'	0	'	'	'	'
Realized (losses) gains on foreign currency contracts	($1,100,000)	$1,800,000	($1,900,000)	$4,100,000	'	'	'	'	'

Schedule_of_Fair_Value_of_Fina

Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	$852,516	$857,960
U.S. Treasury Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	404,942	467,895
U.S. Government Agency Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	228,075	202,588
Commercial Paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	108,459	105,598
Corporate Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	82,490	65,387
Equity And Debt Mutual Funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	14,441	13,156
Certificates of Deposit and Time Deposits	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	14,030	3,258
Non-U.S. Government Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	79	78
Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Derivatives assets	'	153
Available for sale securities	1,107,141	'
Total including derivatives	1,107,141	1,199,751
Contingent consideration	2,230	2,230
Derivatives liabilities	306	'
Liabilities	2,536	2,230
Fair Value, Measurements, Recurring | Cash	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Cash and Cash equivalents	136,730	117,242
Fair Value, Measurements, Recurring | Cash Equivalents	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Cash and Cash equivalents	117,895	224,396
Fair Value, Measurements, Recurring | U.S. Treasury Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	404,942	467,895
Fair Value, Measurements, Recurring | U.S. Government Agency Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	228,075	202,588
Fair Value, Measurements, Recurring | Commercial Paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	108,459	105,598
Fair Value, Measurements, Recurring | Corporate Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	82,490	65,387
Fair Value, Measurements, Recurring | Equity And Debt Mutual Funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	14,441	13,156
Fair Value, Measurements, Recurring | Certificates of Deposit and Time Deposits	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	14,030	3,258
Fair Value, Measurements, Recurring | Non-U.S. Government Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	79	78
Fair Value, Measurements, Recurring | Subtotal	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	'	1,199,598
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	263,323	'
Total including derivatives	263,323	296,263
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Cash	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Cash and Cash equivalents	136,730	117,242
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Cash Equivalents	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Cash and Cash equivalents	112,152	165,865
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Equity And Debt Mutual Funds	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	14,441	13,156
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Subtotal	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	'	296,263
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Derivatives assets	'	153
Available for sale securities	843,818	'
Total including derivatives	843,818	903,488
Derivatives liabilities	306	'
Liabilities	306	'
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Cash Equivalents	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Cash and Cash equivalents	5,743	58,531
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. Treasury Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	404,942	467,895
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. Government Agency Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	228,075	202,588
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Commercial Paper	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	108,459	105,598
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate Debt Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	82,490	65,387
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Certificates of Deposit and Time Deposits	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	14,030	3,258
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Non-U.S. Government Securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	79	78
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Subtotal	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Available for sale securities	'	903,335
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Contingent consideration	2,230	2,230
Liabilities	$2,230	$2,230

Schedule_of_Reported_Financial

Schedule of Reported Financial Assets and Liabilities (Detail) (Fair Value, Measurements, Recurring, USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	$1,107,141	$1,199,751
Liabilities	2,536	2,230
Other Accrued Liabilities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Liabilities	306	'
Other current assets	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	'	153
Cash and Cash Equivalents	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	254,625	341,638
Marketable securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	488,439	586,882
Long-term marketable securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	364,077	271,078
Long-term other accrued liabilities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Liabilities	2,230	2,230
Quoted Prices in Active Markets for Identical Instruments (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	263,323	296,263
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Cash and Cash Equivalents	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	248,882	283,107
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Long-term marketable securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	14,441	13,156
Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	843,818	903,488
Liabilities	306	'
Significant Other Observable Inputs (Level 2) | Other Accrued Liabilities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Liabilities	306	'
Significant Other Observable Inputs (Level 2) | Other current assets	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	'	153
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	5,743	58,531
Significant Other Observable Inputs (Level 2) | Marketable securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	488,439	586,882
Significant Other Observable Inputs (Level 2) | Long-term marketable securities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Assets	349,636	257,922
Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Liabilities	2,230	2,230
Significant Unobservable Inputs (Level 3) | Long-term other accrued liabilities	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Liabilities	$2,230	$2,230

Schedule_of_Changes_in_Fair_Va

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Mar. 30, 2014	Jun. 30, 2013	Mar. 31, 2013
Fair Value Measurements	'	'	'	'
Beginning Balance	$2,230	$2,230	$75	$388
Contingent consideration payments	0	0	-75	-313
Ending Balance	$2,230	$2,230	$0	$75

Schedule_of_Carrying_Amounts_a

Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) (USD $)	Jun. 29, 2014	Dec. 31, 2013		Jun. 30, 2013	Dec. 31, 2012	Mar. 31, 2009
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions	'	'		'	'	'
Cash and cash equivalents, Carrying Value	$254,625	$341,638		$227,601	$338,920	'
Convertible debt, Carrying Value	0	185,708		'	'	'
Japan loan, Carrying Value	'	'		'	'	10,000
Carrying Value	'	'		'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions	'	'		'	'	'
Cash and cash equivalents, Carrying Value	254,625	341,638		'	'	'
Marketable securities, Carrying Value	852,516	857,960		'	'	'
Convertible debt, Carrying Value	'	185,708	[1]	'	'	'
Japan loan, Carrying Value	'	955		'	'	'
Fair Value	'	'		'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions	'	'		'	'	'
Cash and cash equivalents, Fair Value	254,625	341,638		'	'	'
Marketable securities, Fair Value	852,516	857,960		'	'	'
Convertible debt, Fair Value	'	611,433	[1]	'	'	'
Japan loan, Fair Value	'	$955		'	'	'
[1]	The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion feature.

Schedule_of_Available_for_Sale

Schedule of Available for Sale Marketable Securities (Detail) (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	$847,486	$855,786
Available-for-sale marketable securities, Unrealized Gain	5,327	3,689
Available-for-sale marketable securities, Unrealized (Loss)	-297	-1,515
Available-for-sale marketable securities, Fair Market Value	852,516	857,960
Available-for-sale marketable securities, Fair Market Value of Investment with Unrealized Losses	104,322	241,760
U.S. Government Agency Securities	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	227,889	202,573
Available-for-sale marketable securities, Unrealized Gain	202	75
Available-for-sale marketable securities, Unrealized (Loss)	-16	-60
Available-for-sale marketable securities, Fair Market Value	228,075	202,588
Available-for-sale marketable securities, Fair Market Value of Investment with Unrealized Losses	41,122	84,498
U.S. Treasury Securities	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	404,707	468,084
Available-for-sale marketable securities, Unrealized Gain	308	94
Available-for-sale marketable securities, Unrealized (Loss)	-73	-283
Available-for-sale marketable securities, Fair Market Value	404,942	467,895
Available-for-sale marketable securities, Fair Market Value of Investment with Unrealized Losses	36,402	108,212
Commercial Paper	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	108,446	105,583
Available-for-sale marketable securities, Unrealized Gain	13	16
Available-for-sale marketable securities, Unrealized (Loss)	'	-1
Available-for-sale marketable securities, Fair Market Value	108,459	105,598
Available-for-sale marketable securities, Fair Market Value of Investment with Unrealized Losses	'	7,993
Corporate Debt Securities	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	80,771	65,747
Available-for-sale marketable securities, Unrealized Gain	1,903	762
Available-for-sale marketable securities, Unrealized (Loss)	-184	-1,122
Available-for-sale marketable securities, Fair Market Value	82,490	65,387
Available-for-sale marketable securities, Fair Market Value of Investment with Unrealized Losses	25,959	40,355
Equity And Debt Mutual Funds	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	11,567	10,463
Available-for-sale marketable securities, Unrealized Gain	2,898	2,742
Available-for-sale marketable securities, Unrealized (Loss)	-24	-49
Available-for-sale marketable securities, Fair Market Value	14,441	13,156
Available-for-sale marketable securities, Fair Market Value of Investment with Unrealized Losses	839	702
Certificates of Deposit and Time Deposits	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	14,027	3,258
Available-for-sale marketable securities, Unrealized Gain	3	'
Available-for-sale marketable securities, Fair Market Value	14,030	3,258
Non-U.S. Government Securities	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	79	78
Available-for-sale marketable securities, Fair Market Value	$79	$78

Schedule_of_Reported_Available

Schedule of Reported Available for Sale Marketable Securities (Detail) (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	$847,486	$855,786
Available-for-sale marketable securities, Unrealized Gain	5,327	3,689
Available-for-sale marketable securities, Unrealized (Loss)	-297	-1,515
Available-for-sale marketable securities, Fair Market Value	852,516	857,960
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	104,322	241,760
Marketable securities	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	488,257	586,818
Available-for-sale marketable securities, Unrealized Gain	186	85
Available-for-sale marketable securities, Unrealized (Loss)	-4	-21
Available-for-sale marketable securities, Fair Market Value	488,439	586,882
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	26,407	137,670
Long-term marketable securities	'	'
Schedule of Available-for-sale Securities	'	'
Available-for-sale marketable securities, Cost	359,229	268,968
Available-for-sale marketable securities, Unrealized Gain	5,141	3,604
Available-for-sale marketable securities, Unrealized (Loss)	-293	-1,494
Available-for-sale marketable securities, Fair Market Value	364,077	271,078
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$77,915	$104,090

Contractual_Maturities_of_Inve

Contractual Maturities of Investments Held (Detail) (USD $)	Jun. 29, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities	'
Due within one year, cost	$488,257
Due after 1 year through 5 years, cost	317,047
Due after 5 years through 10 years, cost	6,289
Due after 10 years, cost	24,326
Total, cost	835,919
Due within one year, fair value	488,439
Due after 1 year through 5 years, fair value	317,321
Due after 5 years through 10 years, fair value	6,467
Due after 10 years, fair value	25,848
Total, fair value	$838,075

Schedule_of_Effect_of_Derivati

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013	Dec. 31, 2013
Fair Value, Option, Quantitative Disclosures	'	'	'	'	'
Derivatives not designated as hedging instruments	$306	'	$306	'	$153
Foreign exchange contracts derivatives not designated as hedging instruments, Gains (Losses) Recognized in Statement of Operations	-1,122	1,818	-1,869	4,067	'
Interest Expense and Other	'	'	'	'	'
Fair Value, Option, Quantitative Disclosures	'	'	'	'	'
Foreign exchange contracts derivatives not designated as hedging instruments, Gains (Losses) Recognized in Statement of Operations	-1,122	1,818	-1,869	4,067	'
Not Designated as Hedging Instrument | Foreign Currency Forward Contracts | Other current assets	'	'	'	'	'
Fair Value, Option, Quantitative Disclosures	'	'	'	'	'
Derivatives asset not designated as hedging instruments	'	'	'	'	153
Not Designated as Hedging Instrument | Foreign Currency Forward Contracts | Other Accrued Liabilities	'	'	'	'	'
Fair Value, Option, Quantitative Disclosures	'	'	'	'	'
Derivatives liability not designated as hedging instruments	$306	'	$306	'	'

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended				0 Months Ended	1 Months Ended	6 Months Ended
	Mar. 31, 2009	Mar. 30, 2014	Sep. 30, 2013	Jun. 29, 2014	Jun. 30, 2013	Dec. 31, 2013	Mar. 31, 2009	Mar. 13, 2014	Apr. 30, 2009	Jun. 29, 2014
								4.50% Convertible Senior Notes Due March 15, 2014	4.50% Convertible Senior Notes Due March 15, 2014	4.50% Convertible Senior Notes Due March 15, 2014
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	'	'	'
Unsecured loan	'	'	'	'	'	'	4,000,000	'	'	'
Semiannual principal payments of loan	'	1,000,000	1,000,000	'	'	'	'	'	'	'
Aggregate principal amount	'	'	'	0	'	189,998,000	'	'	190,000,000	'
Initial debt conversion price	'	'	'	'	'	'	'	'	$5.47	'
Conversion rate in number of shares	'	'	'	'	'	'	'	'	182.65	131.95
Additional aggregate principal amount	'	'	'	'	'	'	'	'	1,000	'
Senior notes maturity date	'	'	'	'	'	'	'	'	15-Mar-14	'
Number of shares excluded for conversion rate calculation	'	'	'	'	'	'	'	'	'	50.7
Trading days used to determine average price per share	'	'	'	'	'	'	'	'	'	'25 days
Average trading price of common shares	'	'	'	'	'	'	'	'	'	$19.74
Payments of long-term debt	'	'	'	$190,975,000	$1,063,000	'	'	'	'	$190,000,000
Stock issued in conversion of notes	'	'	'	'	'	'	'	'	'	25,100,000
Stock received and retired	'	'	'	'	'	'	'	25,100,000	'	'
Strike price per share of warrant	'	'	'	$7.64	'	'	'	'	'	'
Warrants settled on a daily basis	'	'	'	536,000	'	'	'	'	'	'
Warrant settlement period	'	'	'	'65 days	'	'	'	'	'	'
Common stock shares were issued for warrants exercised	'	'	'	1,900,000	'	'	'	'	'	'

Components_of_Convertible_Seni

Components of Convertible Senior Notes (Detail) (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument	'	'
Debt principal	$0	$189,998
Unamortized debt discount	0	4,290
Net carrying amount of the convertible debt	$0	$185,708

Interest_Expense_on_Convertibl

Interest Expense on Convertible Senior Notes (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Debt Instrument	'	'	'	'
Contractual interest expense	$0	$2,137	$1,757	$4,274
Amortization of the discount component and debt issue fees	0	4,087	4,493	8,044
Total interest expense on the convertible debt	$0	$6,224	$6,250	$12,318

Schedule_of_Prepayments_Detail

Schedule of Prepayments (Detail) (USD $)	Jun. 29, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Prepaid Expenses [Line Items]	'	'
Contract manufacturer prepayments	$92,196	$115,388
Prepaid maintenance and other services	6,838	6,538
Prepaid taxes	1,960	3,281
Other prepayments	9,479	11,167
Prepayments	$110,473	$136,374

Deferred_Revenue_and_Customer_2

Deferred Revenue and Customer Advances (Detail) (USD $)	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred Revenue Arrangement	'	'	'	'	'	'
Extended warranty	$40,052	$33,949	$34,909	$34,854	$28,599	$26,987
Equipment maintenance and training	26,535	'	22,455	'	'	'
Customer advances	8,926	'	4,825	'	'	'
Undelivered elements	5,831	'	6,971	'	'	'
Customer acceptance	1,616	'	'	'	'	'
Total deferred revenue and customer advances	$82,960	'	$69,160	'	'	'

Warranty_Accrual_Included_in_O

Warranty Accrual Included in Other Accrued Liabilities (Detail) (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Schedule of Accrued Liabilities [Line Items]	'	'	'	'
Balance at beginning of period	$6,615	$7,075	$6,660	$9,786
Accruals for warranties issued during the period	5,399	3,684	8,257	5,107
Adjustments related to pre-existing warranties	-302	-869	-442	-1,798
Settlements made during the period	-2,639	-2,539	-5,402	-5,744
Balance at end of period	$9,073	$7,351	$9,073	$7,351

Extended_Product_Warranty_Incl

Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Schedule of Accrued Liabilities [Line Items]	'	'	'	'
Balance at beginning of period	$33,949	$28,599	$34,909	$26,987
Deferral of new extended warranty revenue	11,960	8,734	14,321	12,205
Recognition of extended warranty deferred revenue	-5,857	-2,479	-9,178	-4,338
Balance at end of period	$40,052	$34,854	$40,052	$34,854

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)

1 Months Ended

6 Months Ended

1 Months Ended

6 Months Ended

1 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Jan. 31, 2014

Jun. 29, 2014

Jun. 30, 2013

Jun. 29, 2014

Jun. 30, 2013

Jun. 29, 2014

Jun. 29, 2014

Jan. 24, 2014

Jan. 31, 2014

Jun. 29, 2014

Jan. 24, 2014

Jan. 31, 2014

Jan. 31, 2014

Service-Based Restricted Stock Units

Service-Based Restricted Stock Units

Restricted Stock Units

Stock Options

Stock Options

TSR Performance-Based Restricted Stock Units

TSR Performance-Based Restricted Stock Units

TSR Performance-Based Restricted Stock Units

TSR Performance-Based Restricted Stock Units

TSR Performance-Based Restricted Stock Units

Employees

Maximum

Minimum

Share-based Compensation Arrangement by Share-based Payment Award

'

'

'

'

'

'

'

'

'

'

'

'

'

Total shareholder return performance measurement period

'

'

'

'

'

'

'

'

'3 years

'

'

'

'

Percentage of vesting of target shares upon performance achieved

'

'

'

'

'

'

'

'

'

'

'

200.00%

0.00%

Restricted stock unit awards to employees

'

'

'

1.6

1.9

'

'

'

'

0.1

'

'

'

Weighted average grant date fair value of restricted stock units granted

'

'

'

$19.08

$16.60

'

'

'

'

$22.06

'

'

'

Estimated annual dividend amount per share

'

'

'

'

'

'

$0.24

'

'

$0.24

'

'

'

Stock price

'

'

'

'

'

'

'

$19.16

'

'

$19.16

'

'

Number of service-based stock options granted to executive officers

'

0.1

0.2

'

'

'

'

'

'

'

'

'

'

Weighted average grant date fair value of stock options granted to executive officers

'

$5.49

$6.09

'

'

'

'

'

'

'

'

'

'

Period of stock granted to employees and executive officers vest in equal installments

'

'

'

'

'

'4 years

'4 years

'

'

'

'

'

'

Stock options term

'

'7 years

'

'

'

'

'

'

'

'

'

'

'

Stock based compensation expense related to retirement agreement

$6,600,000

'

'

'

'

'

'

'

'

'

'

'

'

Schedule_of_Estimated_Fair_Val

Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail) (TSR Performance-Based Restricted Stock Units)	6 Months Ended
	Jun. 29, 2014
TSR Performance-Based Restricted Stock Units	'
Share-based Compensation Arrangement by Share-based Payment Award	'
Risk-free interest rate	0.75%
Teradyne volatility-historical	36.10%
Philadelphia Semiconductor Index volatility-historical	24.60%
Dividend yield	1.25%

Schedule_of_Estimated_Fair_Val1

Schedule of Estimated Fair Value of Stock Options Assumptions (Detail) (Stock Options)	6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013
Stock Options	'	'
Share-based Compensation Arrangement by Share-based Payment Award	'	'
Expected life (years)	'4 years	'4 years
Risk-free interest rate	1.20%	0.60%
Volatility-historical	38.80%	46.80%
Dividend yield	1.25%	0.00%

Changes_in_Accumulated_Other_C

Changes in Accumulated Other Comprehensive Income Balances (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Beginning balance	'	'	$4,000	'
Other comprehensive income before reclassifications, net of tax	'	'	2,304	'
Amounts reclassified from accumulated other comprehensive income, net of tax	-346	-137	-595	-350
Other comprehensive income (loss)	819	-1,600	1,709	-1,613
Ending balance	5,709	'	5,709	'
Unrealized Gains on Marketable Securities	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Beginning balance	'	'	1,381	'
Other comprehensive income before reclassifications, net of tax	'	'	2,304	'
Amounts reclassified from accumulated other comprehensive income, net of tax	'	'	-448	'
Other comprehensive income (loss)	'	'	1,856	'
Ending balance	3,237	'	3,237	'
Retirement Plans Prior Service Benefit	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Beginning balance	'	'	2,619	'
Amounts reclassified from accumulated other comprehensive income, net of tax	'	'	-147	'
Other comprehensive income (loss)	'	'	-147	'
Ending balance	$2,472	'	$2,472	'

Changes_in_Accumulated_Other_C1

Changes in Accumulated Other Comprehensive Income Balances (Parenthetical) (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'	'
Other comprehensive income before reclassifications, tax	$558	($841)	$1,242	($726)	'
Other comprehensive income before reclassifications, tax	'	'	0	'	'
Amounts reclassified from accumulated other comprehensive income, tax	-141	-39	-243	-122	'
Amounts reclassified from accumulated other comprehensive income, tax	-42	-40	-85	-79	'
Unrealized gains on marketable securities, tax	1,793	'	1,793	'	794
Retirement plans prior service benefit, tax	-369	'	-369	'	-284
Unrealized Gains on Marketable Securities	'	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'	'
Other comprehensive income before reclassifications, tax	'	'	1,242	'	'
Amounts reclassified from accumulated other comprehensive income, tax	'	'	-243	'	'
Retirement Plans Prior Service Benefit	'	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'	'
Other comprehensive income before reclassifications, tax	'	'	0	'	'
Amounts reclassified from accumulated other comprehensive income, tax	'	'	($85)	'	'

Reclassification_Out_of_Accumu

Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Detail) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014		Jun. 30, 2013		Jun. 29, 2014		Jun. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Unrealized gains	$272		$68		$448		$212
Prior service benefit	74	[1]	69	[1]	147	[1]	138	[1]
Total reclassifications	$346		$137		$595		$350
[1]	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: "Retirement Plans."

Reclassification_Out_of_Accumu1

Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Parenthetical) (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Unrealized gains, tax	$141	$39	$243	$122
Prior service benefit, tax	$42	$40	$85	$79

Schedule_of_Amortizable_Intang

Schedule of Amortizable Intangible Assets (Detail) (USD $)	6 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets	'	'
Gross Carrying Amount	$515,464	$515,464
Accumulated Amortization	299,716	263,173
Net Carrying Amount	215,748	252,291
Weighted Average Useful Life, years	'6 years 10 months 24 days	'6 years 10 months 24 days
Developed technology	'	'
Finite-Lived Intangible Assets	'	'
Gross Carrying Amount	342,933	342,933
Accumulated Amortization	200,154	174,563
Net Carrying Amount	142,779	168,370
Weighted Average Useful Life, years	'6 years 2 months 12 days	'6 years 2 months 12 days
Customer Relationships	'	'
Finite-Lived Intangible Assets	'	'
Gross Carrying Amount	141,497	141,497
Accumulated Amortization	86,145	76,963
Net Carrying Amount	55,352	64,534
Weighted Average Useful Life, years	'8 years	'8 years
Trade names and trademarks	'	'
Finite-Lived Intangible Assets	'	'
Gross Carrying Amount	30,034	30,034
Accumulated Amortization	12,417	10,647
Net Carrying Amount	17,617	19,387
Weighted Average Useful Life, years	'9 years 1 month 6 days	'9 years 1 month 6 days
Customer backlog	'	'
Finite-Lived Intangible Assets	'	'
Gross Carrying Amount	1,000	1,000
Accumulated Amortization	$1,000	$1,000
Weighted Average Useful Life, years	'4 months 24 days	'4 months 24 days

Intangible_Assets_Additional_I

Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Goodwill and Intangible Assets Disclosure [Line Items]	'	'	'	'
Aggregate intangible asset amortization expense	$18,271	$18,063	$36,542	$36,099

Schedule_of_Estimated_Intangib

Schedule of Estimated Intangible Asset Amortization Expense (Detail) (USD $)	Jun. 29, 2014
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets	'
2014 (remainder)	$33,598
2015	53,391
2016	53,391
2017	47,232
2018	$22,691

Computation_of_Basic_and_Dilut

Computation of Basic and Diluted Net Income Per Common Share (Detail) (USD $)	3 Months Ended				6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 29, 2014		Jun. 30, 2013		Jun. 29, 2014		Jun. 30, 2013
Net Income Loss Per Common Share	'		'		'		'
Net income for basic and diluted net income per share	$101,205		$66,556		$102,134		$73,145
Weighted average common shares-basic	194,408		190,569		193,860		190,128
Incremental shares from assumed conversion of convertible notes	'		23,266	[1]	10,026	[1]	23,326	[1]
Convertible note hedge warrant shares	20,406	[2]	18,689	[2]	20,674	[2]	18,774	[2]
Employee stock purchase rights	43		59		32		43
Dilutive potential common shares	22,160		44,340		32,666		44,705
Weighted average common shares-diluted	216,568		234,909		226,526		234,833
Net income per common share-basic	$0.52		$0.35		$0.53		$0.38
Net income per common share-diluted	$0.47		$0.28		$0.45		$0.31
Restricted Stock Units	'		'		'		'
Net Income Loss Per Common Share	'		'		'		'
Incremental shares attributable to share based payment arrangements	705		772		878		947
Stock Option	'		'		'		'
Net Income Loss Per Common Share	'		'		'		'
Incremental shares attributable to share based payment arrangements	1,006		1,554		1,056		1,615
[1]	Incremental shares from conversion of the convertible notes for the six months ended June 29, 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 six months ended June 29, 2014. Incremental shares from assumed conversion of the convertible notes for the three and six months ended June 30, 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 and six months ended June 29, 2014 and June 30, 2013 are calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.6389, multiplied by the weighted average warrant shares outstanding. The result of this calculation, representing the total intrinsic value of the warrant, is divided by the average Teradyne stock price for the period.

Computation_of_Basic_and_Dilut1

Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail) (USD $)	3 Months Ended	6 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Net Income Loss Per Common Share	'	'	'
Shares that would be issued upon conversion	34.7	34.7	34.7
Convertible Notes	'	'	'
Net Income Loss Per Common Share	'	'	'
Initial debt conversion price	5.475	5.475	5.475
Convertible Notes Hedge Warrant	'	'	'
Net Income Loss Per Common Share	'	'	'
Initial debt conversion price	7.6389	7.6389	7.6389

Net_Income_Per_Common_Share_Ad

Net Income Per Common Share - Additional Information (Detail)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Net Income Loss Per Common Share	'	'	'	'
Exercise of stock options	0.3	0.5	0.3	0.5

Restructuring_and_Other_Additi

Restructuring and Other - Additional Information (Detail) (USD $)	Jun. 29, 2014	Jun. 29, 2014	Jun. 29, 2014	Jun. 30, 2013
		Q3 2014 Activity	Wireless Test	System Test and Semiconductor Test
			Employee
Restructuring Cost and Reserve	'	'	'	'
Severance benefit and charges	'	'	$600,000	$600,000
Reduction in employees head count	'	'	28	'
Accrual balance for severance and benefits	$252,000	$252,000	'	'

Schedule_of_Restructuring_and_

Schedule of Restructuring and Other Net (Detail) (USD $)

Jun. 29, 2014

Dec. 31, 2013

Mar. 30, 2014

Dec. 31, 2013

Jun. 29, 2014

Mar. 30, 2014

Dec. 31, 2013

Jun. 29, 2014

Jun. 29, 2014

Dec. 31, 2013

Mar. 30, 2014

Dec. 31, 2013

Jun. 29, 2014

Mar. 30, 2014

Dec. 31, 2013

Jun. 29, 2014

Dec. 31, 2013

In Thousands, unless otherwise specified

Pre-2013 Activities

Q3 2013 Activity

Q3 2013 Activity

Q3 2013 Activity

Q4 2013 Activity

Q4 2013 Activity

Q2 2014 Activity

Severance and Benefits

Severance and Benefits

Severance and Benefits

Severance and Benefits

Severance and Benefits

Severance and Benefits

Severance and Benefits

Severance and Benefits

Facility Exit Costs

Pre-2013 Activities

Q3 2013 Activity

Q3 2013 Activity

Q3 2013 Activity

Q4 2013 Activity

Q4 2013 Activity

Q2 2014 Activity

Pre-2013 Activities

Restructuring Cost and Reserve

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Beginning Balance

$252

$1,327

$371

'

$210

$114

'

'

$252

$243

$371

'

$210

$114

'

'

$1,084

Provision

'

'

'

1,337

'

'

600

572

'

'

'

1,337

'

'

600

572

'

Change in estimate

'

-553

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-553

Cash payments

'

-774

-161

-966

'

-114

-486

-530

'

-243

-161

-966

'

-114

-486

-530

-531

Ending balance

$252

$0

$210

$371

$210

'

$114

$42

$252

$0

$210

$371

$210

'

$114

$42

$0

Retirement_Plans_Additional_In

Retirement Plans - Additional Information (Detail) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 29, 2014
U.S. Supplemental Executive Defined Benefit Pension Plan	'
Defined Benefit Plan Disclosure	'
Contribution to defined benefit pension plans	$0.90
Foreign Pension Plans, Defined Benefit	'
Defined Benefit Plan Disclosure	'
Contribution to defined benefit pension plans	$1

Schedule_of_Net_Periodic_Pensi

Schedule of Net Periodic Pension and Postretirement Cost (Benefit) (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Defined Benefit Plan Disclosure	'	'	'	'
Actuarial gain	'	'	'	($1,359)
Defined Benefit Pension Plans	'	'	'	'
Defined Benefit Plan Disclosure	'	'	'	'
Service cost	811	852	1,607	1,686
Interest cost	3,732	3,281	7,452	6,651
Expected return on plan assets	-3,384	-3,631	-6,725	-7,261
Amortization of unrecognized prior service benefit	34	41	67	82
Actuarial gain	362	-1,123	362	-1,123
Total net periodic pension/ postretirement cost (benefit)	1,555	-580	2,763	35
Postretirement Benefit Plans	'	'	'	'
Defined Benefit Plan Disclosure	'	'	'	'
Service cost	17	21	29	37
Interest cost	82	84	168	171
Amortization of unrecognized prior service benefit	-150	-150	-299	-299
Actuarial gain	-247	-236	-247	-236
Total net periodic pension/ postretirement cost (benefit)	($298)	($281)	($349)	($327)

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 29, 2014
Purchase Commitment, Excluding Long-term Commitment	'
Aggregate purchase commitments	222.5
Purchase commitments less than one year	211.5
Maximum	'
Purchase Commitment, Excluding Long-term Commitment	'
Purchase commitments period	'1 year

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Income Taxes [Line Items]	'	'	'	'
Effective tax rate	17.00%	17.00%	15.00%	7.00%
U.S. statutory federal tax rate	'	'	35.00%	'
Tax savings due to the tax holiday	'	'	$6.10	'
Tax savings due to the tax holiday, per share	'	'	$0.03	'
Tax holiday expiration date	'	'	'December 31, 2015	'

Schedule_of_Segment_Informatio

Schedule of Segment Information (Detail) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014		Jun. 30, 2013		Jun. 29, 2014		Jun. 30, 2013
Segment Reporting Information [Line Items]	'		'		'		'
Net revenues	$525,567		$428,889		$846,577		$709,256
Income (loss) before income taxes	121,392	[1],[2]	80,357	[1],[2]	119,519	[1],[2]	78,931	[1],[2]
Semiconductor Test	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Net revenues	421,434		292,431		683,171		503,937
Income (loss) before income taxes	107,270	[1],[2]	58,606	[1],[2]	141,870	[1],[2]	72,372	[1],[2]
Wireless Test	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Net revenues	68,699		99,386		89,909		132,984
Income (loss) before income taxes	14,229	[1],[2]	23,913	[1],[2]	-10,856	[1],[2]	13,916	[1],[2]
System Test	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Net revenues	35,434		37,072		73,497		72,335
Income (loss) before income taxes	-715	[1],[2]	779	[1],[2]	-267	[1],[2]	2,309	[1],[2]
Corporate And Eliminations	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Income (loss) before income taxes	$608	[1],[2]	($2,941)	[1],[2]	($11,228)	[1],[2]	($9,666)	[1],[2]
[1]	Pension and postretirement actuarial gains and losses, interest income, and interest expense and other are included in Corporate and Eliminations.
[2]	Included in the income (loss) before income taxes for each of the segments are charges and credits for the three and six months ended June 29, 2014 and June 30, 2013 that include restructuring and other, and provision for excess and obsolete inventory, as follows:

Schedule_of_Segment_Reporting_

Schedule of Segment Reporting Information by Segment Charges (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Restructuring and other	$572	$259	$572	$591
Semiconductor Test	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Cost of revenues-provision for excess and obsolete inventory	3,713	287	9,918	500
Total	3,713	287	9,918	500
System Test	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Cost of revenues-provision for excess and obsolete inventory	440	290	1,181	1,209
Restructuring and other	146	131	146	375
Total	586	421	1,327	1,584
Wireless Test	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Cost of revenues-provision for excess and obsolete inventory	879	1,398	3,972	4,066
Restructuring and other	426	'	426	'
Total	$1,305	$1,398	$4,398	$4,066

Shareholders_Equity_Additional

Shareholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended		44 Months Ended	1 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Jan. 31, 2014	Jun. 29, 2014	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Nov. 30, 2010
						Maximum
Stockholders Equity Note Disclosure [Line Items]	'	'	'	'	'	'
Stock repurchase program, authorized amount	'	'	'	'	'	$200,000,000
Repurchase of stock, shares	'	0	'	0	2.6	'
Repurchase of stock, value	'	'	'	'	31,200,000	'
Common stock average price	'	'	'	'	$11.84	'
Dividends payable, amount per share	$0.06	'	'	'	'	'
Dividends payable, date to be paid	2-Jun-14	'	'	'	'	'
Dividends payable, record date	9-May-14	'	'	'	'	'
Dividend payment	$11,700,000	'	$11,656,000	'	'	'