Teradyne (TER) 10-K 29 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 22, 2016	Jul. 02, 2015
Document Information
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	TER
Entity Registrant Name	TERADYNE, INC
Entity Central Index Key	97,210
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		204,336,493
Entity Public Float			$ 4,100,000,000

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents		$ 264,705	$ 294,256
Marketable securities		477,696	533,787
Accounts receivable, less allowance for doubtful accounts of $2,407 and $2,491 in 2015 and 2014, respectively		211,293	151,034
Inventories:
Parts		73,117	70,821
Assemblies in process		32,825	10,347
Finished goods		47,646	23,961
Inventory, Net, Total		153,588	105,129
Deferred tax assets		54,973	57,239
Prepayments		91,519	95,819
Other current assets		6,194	6,582
Total current assets		1,259,968	1,243,846
Property, plant and equipment, net		273,414	329,038
Marketable securities		265,928	470,789
Deferred tax assets		7,404	7,494
Other assets		13,080	10,419
Retirement plans assets		636	12,896
Intangible assets, net		239,831	190,600
Goodwill		488,413	273,438
Total assets	[1]	2,548,674	2,538,520
Current liabilities:
Accounts payable		92,358	47,763
Accrued employees' compensation and withholdings		113,994	100,994
Deferred revenue and customer advances		85,527	71,603
Other accrued liabilities		43,727	50,247
Contingent consideration		15,500	895
Accrued income taxes		21,751	20,049
Total current liabilities		372,857	291,551
Long-term deferred revenue and customer advances		25,745	19,929
Retirement plans liabilities		103,531	108,460
Deferred tax liabilities		26,663	23,315
Long-term other accrued liabilities		32,156	13,830
Long-term contingent consideration		21,936	2,455
Total liabilities		$ 582,888	$ 459,540
Commitments and contingencies (Note J)
SHAREHOLDERS' EQUITY
Common stock, $0.125 par value, 1,000,000 shares authorized, 203,641 and 216,613 shares issued and outstanding at December 31, 2015 and 2014, respectively		$ 25,455	$ 27,077
Additional paid-in capital		1,480,647	1,437,135
Accumulated other comprehensive (loss) income		(8,144)	4,689
Retained earnings		467,828	610,079
Total shareholders' equity		1,965,786	2,078,980
Total liabilities and shareholders' equity		$ 2,548,674	$ 2,538,520
[1]	Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable, less allowance for doubtful accounts	$ 2,407	$ 2,491
Common stock, par value	$ 0.125	$ 0.125
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	203,641,000	216,613,000
Common stock, shares outstanding	203,641,000	216,613,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended														12 Months Ended
	Dec. 31, 2015	[1],[2]	Oct. 04, 2015	[3]	Jul. 05, 2015	[4]	Apr. 05, 2015	Dec. 31, 2014	[5],[6],[7]	Sep. 28, 2014	[5],[8]	Jun. 29, 2014	[5]	Mar. 30, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Revenues:
Products	$ 244,510		$ 386,488		$ 437,243		$ 272,325	$ 253,162		$ 402,987		$ 452,488		$ 255,386	$ 1,340,566		$ 1,364,024		$ 1,154,922
Services	73,934		79,506		75,496		70,076	70,074		75,023		73,079		65,624	299,012		283,800		273,011
Total revenues	318,444		465,994		512,739		342,401	323,236		478,010		525,567		321,010	1,639,578	[9]	1,647,824	[9]	1,427,933	[9]
Cost of revenues:
Cost of products	120,322		170,963		181,491		118,996	131,337		182,591		202,411		124,448	591,772		640,787		499,030
Cost of services	32,096		36,405		32,680		30,982	31,673		34,298		32,743		29,515	132,163		128,229		120,102
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	152,418		207,368		214,171		149,978	163,010		216,889		235,154		153,963	723,935		769,016		619,132
Gross profit	166,026		258,626		298,568		192,423	160,226		261,121		290,413		167,047	915,643		878,808		808,801
Operating expenses:
Engineering and development	70,941		74,027		75,832		71,450	79,188		71,953		73,414		67,085	292,250		291,639		264,055
Selling and administrative	79,718		77,481		77,073		72,041	91,157		73,064		77,489		78,003	306,313		319,713		279,560
Goodwill impairment								98,897									98,897		0
Acquired intangible assets amortization	19,911		20,053		15,258		13,808	15,957		18,271		18,271		18,271	69,031		70,771		72,447
Restructuring and other	5,204		261		(385)			1,198		(405)		572			5,080		1,365		2,080
Total operating expenses	175,774		171,822		167,778		157,299	286,397		162,883		169,746		163,359	672,674		782,385		618,142
Income from operations	(9,748)		86,804		130,790		35,124	(126,171)		98,238		120,667		3,688	242,969		96,423		190,659
Non-operating (income) expenses:
Interest income	(2,017)		(1,708)		(1,674)		(1,816)	(2,035)		(1,922)		(1,266)		(1,036)	(7,214)		(6,259)		(4,129)
Interest expense	762		508		444		162	214		144		159		6,417	1,876		6,934		26,097
Other (income) expense, net	364		596		(116)		(5,660)	463		(654)		382		180	(4,817)		372		(33,231)
Income (loss) before income taxes	(8,857)		87,408		132,136		42,438	(124,813)		100,670		121,392		(1,873)	253,124	[10],[11]	95,376	[10],[11]	201,922	[10],[11]
Income tax provision	(8,216)		15,955		29,257		9,651	(21,002)		17,721		20,187		(2,802)	46,647		14,104		36,975
Net income	$ (641)		$ 71,453		$ 102,879		$ 32,787	$ (103,811)		$ 82,949		$ 101,205		$ 929	$ 206,477		$ 81,272		$ 164,947
Net income per common share:
Basic	$ 0		$ 0.34		$ 0.48		$ 0.15	$ (0.48)		$ 0.40		$ 0.52		$ 0	$ 0.98		$ 0.40		$ 0.86
Diluted	0		0.34		0.48		0.15	(0.48)		0.38		0.47		0	$ 0.97		$ 0.37		$ 0.70
Weighted average common shares-basic															211,544		202,908		190,772
Weighted average common shares-diluted															213,321		222,550		235,599
Cash dividend declared per common share	$ 0.06		$ 0.06		$ 0.06		$ 0.06	$ 0.06		$ 0.06		$ 0.06		$ 0	$ 0.24		$ 0.18
[1]	In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[2]	Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[3]	Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[4]	Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[5]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[6]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[7]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[8]	Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[9]	Revenues attributable to a country are based on location of customer site.
[10]	Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges and goodwill impairment charges.
[11]	Interest income, interest expense, other (income) expense, net, contingent consideration adjustments and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income		$ 206,477	$ 81,272	$ 164,947
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustment, net of tax of $0		(8,759)
Unrealized (losses) gains on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), $1,449, $(216), respectively		(3,075)	2,417	(1,097)
Less: Reclassification adjustment for gains included in net income, net of tax of $(390), $(645), $(257), respectively		(704)	(1,433)	(447)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total		(3,779)	984	(1,544)
Defined benefit pension and post-retirement plans:
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $(169), $(169), $(159), respectively	[1]	(295)	(295)	(276)
Other comprehensive (loss) income		(12,833)	689	(1,820)
Comprehensive income		$ 193,644	$ 81,961	$ 163,127
[1]	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note M: "Retirement Plans."

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Foreign currency translation adjustment, tax	$ 0
Unrealized (losses) gains on marketable securities arising during period, tax	(1,667)	$ 1,449	$ (216)
Amounts reclassified from accumulated other comprehensive income, tax	(390)	(645)	(257)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, tax	$ (169)	$ (169)	$ (159)

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance, at Dec. 31, 2012	$ 1,778,355		$ 23,488	$ 1,347,762	$ 5,820	$ 401,285
Balance, Shares at Dec. 31, 2012			187,908
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax (in shares)			3,823
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax	5,404		$ 478	4,926
Stock-based compensation expense	35,612			35,612
Tax benefit related to stock options and restricted stock units	2,596			2,596
Net income	164,947					164,947
Unrealized gains (losses) on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), $1,449, $(216), respectively	(1,097)				(1,097)
Less: Reclassification adjustment for gains included in net income, net of tax of $(390), $(645), $(257), respectively	(447)				(447)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $(169), $(169), $(159), respectively	(276)	[1]			(276)
Balance, at Dec. 31, 2013	1,985,094		$ 23,966	1,390,896	4,000	566,232
Balance, Shares at Dec. 31, 2013			191,731
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax (in shares)			3,661
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax	9,273		$ 458	8,815
Warrant settlement			$ 2,653	(2,653)
Warrant settlement Shares			21,221
Stock-based compensation expense	39,868			39,868
Tax benefit related to stock options and restricted stock units	209			209
Cash dividends	(37,425)					(37,425)
Net income	81,272					81,272
Unrealized gains (losses) on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), $1,449, $(216), respectively	2,417				2,417
Less: Reclassification adjustment for gains included in net income, net of tax of $(390), $(645), $(257), respectively	(1,433)				(1,433)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $(169), $(169), $(159), respectively	(295)	[1]			(295)
Balance, at Dec. 31, 2014	2,078,980		$ 27,077	1,437,135	4,689	610,079
Balance, Shares at Dec. 31, 2014			216,613
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax (in shares)			2,649
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax	8,933		$ 331	8,602
Stock-based compensation expense	30,285			30,285
Repurchase of common stock	$ (299,949)		$ (1,953)			(297,996)
Repurchase of common stock (in shares)	(15,621)		(15,621)
Tax benefit related to stock options and restricted stock units	$ 4,625			4,625
Cash dividends	(50,732)					(50,732)
Net income	206,477					206,477
Foreign currency translation adjustment	(8,759)				(8,759)
Unrealized gains (losses) on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), $1,449, $(216), respectively	(3,075)				(3,075)
Less: Reclassification adjustment for gains included in net income, net of tax of $(390), $(645), $(257), respectively	(704)				(704)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $(169), $(169), $(159), respectively	(295)	[1]			(295)
Balance, at Dec. 31, 2015	$ 1,965,786		$ 25,455	$ 1,480,647	$ (8,144)	$ 467,828
Balance, Shares at Dec. 31, 2015			203,641
[1]	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note M: "Retirement Plans."

CONSOLIDATED STATEMENTS OF SHA8

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Issuance of stock to employees under benefit plans, shares withheld for payroll tax	$ 10,597	$ 12,018	$ 12,192
Unrealized (losses) gains on marketable securities arising during period, tax	(1,667)	1,449	(216)
Amounts reclassified from accumulated other comprehensive income, tax	(390)	(645)	(257)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, tax	$ (169)	$ (169)	$ (159)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 206,477	$ 81,272	$ 164,947
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Depreciation	68,181	73,390	57,317
Amortization	72,592	79,154	93,370
Stock-based compensation	30,451	40,307	36,612
Goodwill impairment		98,897	0
Provision for excess and obsolete inventory	21,332	22,193	16,592
Deferred taxes	(7,124)	(19,928)	(3,316)
Gain from the sale of an equity investment	(5,406)		(34,212)
Tax benefit related to employee stock compensation awards	(4,715)	(535)	(2,675)
Non cash charge for the sale of inventories revalued at the date of acquisition	1,567
Retirement plans actuarial losses (gains)	17,732	46,564	(10,340)
Contingent consideration adjustment	2,489	(630)
Other	(34)	2,874	(5)
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(57,267)	8,060	(3,656)
Inventories	15,559	51,803	22,282
Prepayments and other assets	3,034	41,537	(49,572)
Accounts payable and other accrued expenses	48,213	(45,430)	15,205
Deferred revenue and customer advances	17,011	22,033	(28,979)
Retirement plan contributions	(12,095)	(33,916)	(5,540)
Income taxes	(5,156)	24,417	680
Net cash provided by operating activities	412,841	492,062	268,710
Cash flows from investing activities:
Purchases of property, plant and equipment	(89,878)	(168,982)	(106,731)
Purchases of available-for-sale marketable securities	(1,424,002)	(1,578,743)	(1,170,506)
Acquisition of businesses, net of cash acquired	(282,741)	(19,419)	(14,999)
Proceeds from maturities of available-for-sale marketable securities	360,264	570,358	516,499
Proceeds from sales of available-for-sale marketable securities	1,316,131	859,729	458,491
Proceeds from (purchases of) life insurance	1,098	4,184	(307)
Proceeds from the sale of an equity investment	5,406		34,212
Net cash used for investing activities	(113,722)	(332,873)	(283,341)
Cash flows from financing activities:
Issuance of common stock under stock option and stock purchase plans	19,530	21,291	17,596
Repurchase of common stock	(299,949)
Tax benefit related to employee stock compensation awards	4,715	535	2,675
Dividend payments	(50,713)	(37,425)
Payment of revolving credit facility costs	(2,253)
Payments of long-term debt		(190,972)	(2,534)
Payments of contingent consideration			(388)
Net cash (used for) provided by financing activities	(328,670)	(206,571)	17,349
(Decrease) increase in cash and cash equivalents	(29,551)	(47,382)	2,718
Cash and cash equivalents at beginning of year	294,256	341,638	338,920
Cash and cash equivalents at end of year	264,705	294,256	341,638
Cash paid for:
Interest	301	4,294	8,590
Income taxes	$ 35,218	$ 25,893	$ 38,156

The Company

The Company	12 Months Ended
	Dec. 31, 2015
The Company	A. THE COMPANY Teradyne, Inc. (“Teradyne”) is a leading global supplier of automation equipment for test and industrial applications. Teradyne designs, develops, manufactures and sells automatic test systems used to test semiconductors, wireless products, data storage and complex electronics systems in the consumer electronics, wireless, automotive, industrial, computing, communications, and aerospace and defense industries. Teradyne’s industrial automation products include collaborative robots used by global manufacturing and light industrial customers to improve quality, increase manufacturing efficiency and decrease manufacturing costs. Teradyne’s automatic test equipment and industrial automation products and services include: • semiconductor test (“Semiconductor Test”) systems; • defense/aerospace (“Defense/Aerospace”) test instrumentation and systems, storage test (“Storage Test”) systems, and circuit-board test and inspection (“Production Board Test”) systems (collectively these products represent “System Test”); • wireless test (“Wireless Test”) systems; and • industrial automation (“Industrial Automation”) products. On June 11, 2015, Teradyne acquired Universal Robots A/S (“Universal Robots”) for approximately $284 million of cash plus up to an additional $65 million of cash if certain performance targets are met extending through 2018. Universal Robots is the leading supplier of collaborative robots which are low-cost, easy-to-deploy and simple-to-program robots that work side by side with production workers. Universal Robots is a separate operating and reportable segment, Industrial Automation.

Accounting Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies	B. ACCOUNTING POLICIES The consolidated financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions are eliminated. Certain prior years’ amounts were reclassified to conform to the current year presentation. Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going basis, management evaluates its estimates, including those related to inventories, investments, goodwill, intangible and other long-lived assets, accounts receivable, income taxes, deferred tax assets, pensions, warranties, and loss contingencies. Management bases its estimates on historical experience and on appropriate and customary assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ significantly from these estimates. Revenue Recognition Teradyne recognizes revenue when there is persuasive evidence of an arrangement, title and risk of loss have passed, delivery has occurred or the services have been rendered, the sales price is fixed or determinable and collection of the related receivable is reasonably assured. Title and risk of loss generally pass to Teradyne’s customers upon shipment or at delivery destination point. In circumstances where either title or risk of loss pass upon destination, acceptance or cash payment, Teradyne defers revenue recognition until such events occur except when title transfer is tied to cash payment outside the United States. Outside the United States, Teradyne recognizes revenue upon shipment or at delivery destination point, even if Teradyne retains a form of title to products delivered to customers, provided the sole purpose is to enable Teradyne to recover the products in the event of customer payment default and the arrangement does not prohibit the customer’s use or resale of the product in the ordinary course of business. Teradyne’s equipment has non-software and software components that function together to deliver the equipment’s essential functionality. Revenue is recognized upon shipment or at delivery destination point, provided that customer acceptance criteria can be demonstrated prior to shipment. Certain contracts require Teradyne to perform tests of the product to ensure that performance meets the published product specifications or customer requested specifications, which are generally conducted prior to shipment. Where the criteria cannot be demonstrated prior to shipment, revenue is deferred until customer acceptance has been received. Teradyne also defers the portion of the sales price that is not due until acceptance, which represents deferred profit. For multiple element arrangements, Teradyne allocates revenue to all deliverables based on their relative selling prices. In such circumstances, a hierarchy is used to determine the selling price for allocating revenue to deliverables as follows: (i) vendor-specific objective evidence of selling price (“VSOE”), (ii) third-party evidence of selling price (“TPE”), and (iii) best estimate of the selling price (“BESP”). For a delivered item to be considered a separate unit the delivered item must have value to the customer on a standalone basis and the delivery or performance of the undelivered item must be considered probable and substantially in Teradyne’s control. Teradyne’s post-shipment obligations include installation, training services, one-year standard warranties, and extended warranties. Installation does not alter the product capabilities, does not require specialized skills or tools and can be performed by the customers or other vendors. Installation is typically provided within five days of product shipment and is completed within one to two days thereafter. Training services are optional and do not affect the customers’ ability to use the product. Teradyne defers revenue for the selling price of installation and training. Extended warranties constitute warranty obligations beyond one year and Teradyne defers revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605-20, “Separately Priced Extended Warranty and Product Maintenance Contracts” “Revenue Recognition Multiple-Element Arrangements.” Teradyne’s products are generally subject to warranty and related costs of the warranty are provided for in cost of revenues when product revenue is recognized. Teradyne classifies shipping and handling costs in cost of revenue. Teradyne does not provide its customers with contractual rights of return for any of its products. As of December 31, 2015 and 2014, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2015 2014 (in thousands) Extended warranty $ 46,499 $ 43,300 Equipment maintenance and training 30,616 30,500 Customer advances 17,456 8,875 Undelivered elements and other 16,701 8,857 Total deferred revenue and customer advances $ 111,272 $ 91,532 Product Warranty Teradyne generally provides a one-year warranty on its products, commencing upon installation, acceptance 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 balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2012 $ 9,786 Accruals for warranties issued during the period 10,574 Accruals related to pre-existing warranties (3,534 ) Settlements made during the period (10,166 ) Balance at December 31, 2013 6,660 Accruals for warranties issued during the period 15,406 Accruals related to pre-existing warranties (2,008 ) Settlements made during the period (11,116 ) Balance at December 31, 2014 8,942 Acquisition 409 Accruals for warranties issued during the period 11,539 Accruals related to pre-existing warranties (3,159 ) Settlements made during the period (10,806 ) Balance at December 31, 2015 $ 6,925 When Teradyne receives revenue for extended warranties, beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2012 $ 28,044 Deferral of new extended warranty revenue 20,630 Recognition of extended warranty deferred revenue (13,765 ) Balance at December 31, 2013 34,909 Deferral of new extended warranty revenue 29,519 Recognition of extended warranty deferred revenue (21,128 ) Balance at December 31, 2014 43,300 Acquisition 870 Deferral of new extended warranty revenue 28,549 Recognition of extended warranty deferred revenue (26,220 ) Balance at December 31, 2015 $ 46,499 Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The volatility of the industries that Teradyne serves can cause certain of its customers to experience shortages of cash flows, which can impact their ability to make required payments. Teradyne maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Estimated allowances for doubtful accounts are reviewed periodically taking into account the customer’s recent payment history, the customer’s current financial statements and other information regarding the customer’s credit worthiness. Account balances are written off against the allowance when it is determined the receivable will not be recovered. Inventories Inventories are stated at the lower of cost (first-in, first-out basis) or net realizable value. On a quarterly basis, Teradyne uses consistent methodologies to evaluate all inventories for net realizable value. Teradyne records a provision for both excess and obsolete inventory when such write-downs or write-offs are identified through the quarterly review process. The inventory valuation is based upon assumptions about future demand, product mix and possible alternative uses. Investments Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, “ Investments—Debt and Equity Securities. • 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. As defined in ASC 820-10, “ Fair Value Measurements and Disclosures, 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. Matrix pricing is a mathematical technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, and therefore is considered a Level 2 input. 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. In accordance with ASC 820-10, Teradyne measures its debt and equity investments at fair value. Teradyne’s debt and equity investments are primarily classified within Level 1 and 2. Acquisition-related contingent consideration is classified within Level 3. Teradyne determines the fair value of acquisition-related contingent consideration based on an assessment of the probability that it would be required to make such payment. Prepayments Prepayments consist of the following and are included in prepayments on the balance sheet: 2015 2014 (in thousands) Contract manufacturer prepayments $ 66,283 $ 65,972 Prepaid maintenance and other services 8,481 7,343 Prepaid taxes 3,781 11,462 Other prepayments 12,974 11,042 Total prepayments $ 91,519 $ 95,819 Retirement and Postretirement Plans Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans. Goodwill, Intangible and Long-Lived Assets Teradyne accounts for goodwill and intangible assets in accordance with ASC 350-10, “Intangibles-Goodwill and Other.” In accordance with ASC 360-10 , “Impairment or Disposal of Long-Lived Assets,” Property, Plant and Equipment Property, plant and equipment are stated at cost and depreciated over the estimated useful lives of the assets. Leasehold improvements and major renewals are capitalized and included in property, plant and equipment accounts while expenditures for maintenance and repairs and minor renewals are charged to expense. When assets are retired, the assets and related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the statement of operations. Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 years Building improvements 5 to 10 years Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 years Machinery and equipment 3 to 5 years Software 3 to 5 years Test systems manufactured internally are used by Teradyne for customer evaluations and manufacturing and support of its customers. Teradyne depreciates the test systems manufactured internally over a six-year life to cost of revenues, engineering and development, and selling and administrative expenses. Teradyne often sells internally manufactured test equipment to customers. Upon the sale of an internally manufactured test system, the net book value of the system is transferred to inventory and expensed as cost of revenues. The net book value of internally manufactured test systems sold in the years ended December 31, 2015, 2014 and 2013 was $50.7 million, $9.7 million and $9.0 million, respectively. Engineering and Development Costs Teradyne’s products are highly technical in nature and require a large and continuing engineering and development effort. Software development costs incurred prior to the establishment of technological feasibility are charged to expense. Software development costs incurred subsequent to the establishment of technological feasibility are capitalized until the product is available for release to customers. To date, the period between achieving technological feasibility and general availability of the product has been short and software development costs eligible for capitalization have not been material. Engineering and development costs are expensed as incurred and consist primarily of salaries, contractor fees, allocated facility costs, depreciation, and tooling costs. Stock Compensation Plans and Employee Stock Purchase Plan Stock-based compensation expense is based on the grant-date fair value estimated in accordance with the provisions of ASC 718-10, “ Compensation-Stock Compensation Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The measurement of deferred tax assets is reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be realized. Teradyne performed the required assessment of positive and negative evidence regarding the realization of the net deferred tax assets in accordance with ASC 740, “Accounting for Income Taxes.” This assessment included the evaluation of scheduled reversals of deferred tax liabilities, estimates of projected future taxable income and tax-planning strategies. Although realization is not assured, based on its assessment, Teradyne concluded that it is more likely than not that such assets, net of the existing valuation allowance, will be realized. U.S. income taxes are not provided for on the earnings of non-U.S. subsidiaries which are expected to be reinvested indefinitely in operations outside the U.S. For intra-period tax allocations, Teradyne first utilizes non-equity related tax attributes, such as net operating losses and credit carryforwards and then equity-related tax attributes. Teradyne uses the with-and-without method for calculating excess stock compensation deductions and does not take into account any indirect impacts of excess stock compensation deductions on its research and development tax credits, domestic production activities deduction, and other differences between financial reporting and tax reporting. Advertising Costs Teradyne expenses all advertising costs as incurred. Advertising costs were $3.3 million, $1.9 million and $1.7 million in 2015, 2014 and 2013, respectively. Translation of Non-U.S. Currencies The functional currency for all subsidiaries is the U.S. dollar, except for the Industrial Automation segment for which the local currency is its functional currency. All foreign currency denominated monetary assets and liabilities are remeasured on a monthly basis into the functional currency using exchange rates in effect at the end of the period. All foreign currency denominated non-monetary assets and liabilities are remeasured into the functional currency using historical exchange rates. Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For Industrial Automation, assets and liabilities are translated into U.S. dollars using exchange rates in effect at the end of the period. Revenue and expense amounts are translated using an average of exchange rates in effect during the period. Translation adjustments are recorded within accumulated other comprehensive income (loss). Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net and were a gain of $2.5 million, a loss of $0.9 million and a loss of $6.9 million, respectively, for the years ended December 31, 2015, 2014 and 2013. These amounts do not reflect the corresponding gains (losses) from foreign exchange contracts. See Note F: “Financial Instruments” regarding foreign exchange contracts. Net Income per Common Share Basic net income per common share is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Except where the result would be antidilutive, diluted net income per common share is calculated by dividing net income by the sum of the weighted average number of common shares plus common stock equivalents, if applicable. Dilutive potential common shares included incremental shares from the assumed conversion of the convertible notes and the convertible notes hedge warrant shares, during the periods the convertible notes and warrants were outstanding. Incremental shares from the assumed conversion of the convertible notes were calculated using the difference between the average Teradyne stock price for the period and the conversion price of $5.48, 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. Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.67, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne’s call option for 34.7 million shares at an exercise price of $5.48 was not used in the GAAP earnings per share calculation as its effect was anti-dilutive. Teradyne settled its conversion spread (i.e., the intrinsic value of the embedded option feature contained in the convertible debt) in shares. Teradyne accounted for its conversion spread using the treasury stock method. Teradyne determined that it had the ability and intent to settle the principal amount of the convertible debt in cash; accordingly, the principal amount was excluded from the determination of diluted earnings per share. Comprehensive Income (Loss) Comprehensive income (loss) includes net income, unrealized pension and postretirement prior service costs and benefits, unrealized gains and losses on investments in debt and equity marketable securities and foreign currency translation adjustment.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2015
Recently Issued Accounting Pronouncements	C. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS In November 2015, the FASB issued Accounting Standards Update (“ASU”) 2015-17, “Balance Sheet Classification of Deferred Taxes ” In September 2015, the FASB issued ASU 2015-16, “Business Combinations (Topic 805)—Simplifying the Accounting for Measurement-Period Adjustments ” On April 7, 2015, the FASB issued ASU 2015-03, “Simplifying the Presentation of Debt Issuance Costs,” “Interest—Imputation of Interest (Subtopic 835-30)” In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),”

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2015
Acquisitions	D. ACQUISITIONS Business Universal Robots On June 11, 2015, Teradyne acquired all of the outstanding equity of Universal Robots located in Odense, Denmark. Universal Robots is the leading supplier of collaborative robots which are low-cost, easy-to-deploy and simple-to-program robots that work side by side with production workers to improve quality, increase manufacturing efficiency and decrease manufacturing costs. Universal Robots is a separate operating and reportable segment, Industrial Automation. The total purchase price of $315.4 million consisted of $283.8 million of cash paid and $31.6 million of contingent consideration, measured at fair value. The contingent consideration was valued using a Monte Carlo simulation based on the following key inputs: (1) forecasted revenue (2) forecasted EBITDA (3) revenue volatility (4) EBITDA volatility; and (5) discount rate. The contingent consideration is payable upon the achievement of certain thresholds and targets for earnings before income taxes, depreciation and amortization (“EBITDA”) for calendar year 2015, revenue for the period from July 1, 2015 to December 31, 2017 and revenue for the period from July 1, 2015 to December 31, 2018. The maximum amount of contingent consideration that could be paid is $65 million. Based on Universal Robots’ calendar 2015 EBITDA results, Teradyne will pay, in the first quarter of 2016, $15 million or 100% of the eligible EBITDA contingent consideration amount. In the fourth quarter of 2015, Teradyne finalized the valuation and purchase price allocation for the acquisition which resulted in a $5.4 million decrease in goodwill as a result of a $2.2 million decrease in the fair value of contingent consideration, a $1.6 million increase in intangible assets and a $1.6 million decrease in acquired liabilities. The Universal Robots acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s consolidated results of operations from the date of acquisition. The allocation of the total purchase price to Universal Robots’ net tangible liabilities and identifiable intangible assets was based on their estimated fair values as of the acquisition date. The excess of the purchase price over the identifiable intangible assets and net tangible liabilities in the amount of $221.1 million was allocated to goodwill, which is not deductible for tax purposes. The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 221,128 Intangible assets 121,590 Tangible assets acquired and liabilities assumed: Current assets 10,853 Non-current assets 3,415 Accounts payable and current liabilities (11,976 ) Long-term deferred tax liabilities (26,653 ) Long-term other liabilities (2,920 ) Total purchase price $ 315,437 Teradyne estimated the fair value of intangible assets using the income and cost approaches. Acquired intangible assets are amortized on a straight-line basis over their estimated useful lives. Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 89,240 4.9 Trademarks and tradenames 22,920 10.0 Customer relationships 9,430 2.0 Total intangible assets $ 121,590 5.6 For the period from June 12, 2015 to December 31, 2015, Universal Robots contributed $41.9 million of revenues and had a $7.6 million loss before income taxes. The following unaudited pro forma information gives effect to the acquisition of Universal Robots as if the acquisition occurred on January 1, 2014. The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Years Ended December 31, December 31, (in thousands, except per Revenue $ 1,657,626 $ 1,686,689 Net income 199,784 61,078 Net income per common share: Basic $ 0.94 $ 0.30 Diluted $ 0.94 $ 0.27 Pro forma results for the year ended December 31, 2015 were adjusted to exclude $1.6 million of non-recurring expense related to the fair value adjustment to acquisition-date inventory and $1.0 million of acquisition related costs incurred in 2015. Pro forma results for the year ended December 31, 2014, were adjusted to include $1.6 million of non-recurring expense related to the fair value adjustment to acquisition-date inventory and $1.0 million of acquisition related costs. Avionics Interface Technologies, LLC. On October 31, 2014, Teradyne acquired all of the assets and liabilities of Avionics Interface Technologies, LLC (“AIT”) located in Omaha, Nebraska and Dayton, Ohio. AIT is a supplier of equipment for testing state-of-the-art data communication buses. The acquisition of AIT complements Teradyne’s Defense/Aerospace line of bus test instrumentation for commercial and defense avionics systems. AIT is included in Teradyne’s System Test segment. The total purchase price of $21.2 million consisted of $19.4 million of cash paid to acquire AIT’s assets and liabilities and $1.8 million in fair value of contingent consideration payable upon the achievement of certain revenue and gross margin targets in 2015 and 2016. No contingent consideration was paid for 2015. The maximum remaining contingent consideration that could be paid is $1.1 million. The valuation of the contingent consideration utilized the following assumptions: (1) probability of meeting each target; (2) expected timing of meeting each target; and (3) discount rate reflecting the risk associated with the expected payments. The probabilities and timing for each target were estimated based on a review of the historical and projected results. A discount rate of 4.7 percent was selected based on the cost of debt for the business. A significant portion of the risk in achieving the contingent consideration was captured in the probabilities assigned to meeting each target. The AIT acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s consolidated results of operations from the date of acquisition. The allocation of the total purchase price of AIT’s net tangible and identifiable intangible assets was based on their estimated fair values as of the acquisition date. The excess of the purchase price over the identifiable intangible and net tangible assets in the amount of $10.5 million was allocated to goodwill, which is deductible for tax purposes. The following represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 10,516 Intangible assets 9,080 Tangible assets acquired and liabilities assumed: Current assets 2,452 Non-current assets 359 Accounts payable and current liabilities (1,164 ) Total purchase price $ 21,243 Teradyne estimated the fair value of intangible assets using the income approach. Acquired intangible assets are amortized on a straight-line basis over their estimated useful lives. Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Customer relationships $ 5,630 5.0 Developed technology 2,580 4.8 Trademarks and tradenames 380 5.0 Non-compete agreement 320 4.0 Customer order backlog 170 0.3 Total intangible assets $ 9,080 4.8 For the period from October 31, 2014 to December 31, 2014, AIT contributed $0.6 million of revenues and had a $0.8 million loss before income taxes. The following unaudited pro forma information gives effect to the acquisition of AIT as if the acquisition occurred on January 1, 2013. The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Year Ended December 31, December 31, (in thousands, except per Revenues $ 1,655,038 $ 1,434,699 Net income $ 82,169 $ 164,087 Income per common share: Basic $ 0.40 $ 0.86 Diluted $ 0.37 $ 0.70 ZTEC Instruments, Inc. On October 25, 2013, Teradyne acquired all of the outstanding equity of ZTEC Instruments, Inc. (“ZTEC”) located in Albuquerque, New Mexico. ZTEC is a supplier of modular wireless test instruments. The acquisition of ZTEC expands Teradyne’s Wireless Test segment into the design verification test of wireless components and chipsets. The total purchase price of $17.3 million consisted of $15.1 million of cash paid to acquire the outstanding common and preferred stock of ZTEC and $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 have been paid was $5.0 million. None of the contingent consideration was paid. The ZTEC acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s consolidated results of operation from the date of acquisition. The allocation of the total purchase price of ZTEC’s net tangible and identifiable intangible assets was based on their estimated fair values as of the acquisition date. The excess of the purchase price over the identifiable intangible and net tangible assets in the amount of $12.5 million was allocated to goodwill, which is not deductible for tax purposes. The following represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 12,520 Intangible assets 4,870 Tangible assets acquired and liabilities assumed: Cash 79 Other current assets 1,612 Non-current assets 1,757 Accounts payable and current liabilities (1,811 ) Long-term deferred tax liabilities (1,719 ) Total purchase price $ 17,308 Teradyne estimated the fair value of intangible assets using the income approach. Acquired intangible assets are amortized on a straight-line basis over their estimated useful lives. Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 3,500 5.0 Customer relationships 1,370 6.0 Total intangible assets $ 4,870 5.3 For the period from October 25, 2013 to December 31, 2013, ZTEC contributed $0.4 million of revenues and had a $0.8 million loss before income taxes. The following unaudited pro forma information gives effect to the acquisition of ZTEC as if the acquisition occurred on January 1, 2013. The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Year Ended December 31, (in thousands, except Revenues $ 1,431,270 Net income $ 163,394 Income per common share: Basic $ 0.86 Diluted $ 0.69

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment	E. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consist of the following: 2015 2014 (in thousands) Land $ 16,561 $ 16,561 Buildings 108,797 108,671 Machinery and equipment 595,445 659,743 Furniture and fixtures, and software 82,612 77,566 Leasehold improvements 43,328 31,981 Construction in progress 2,630 2,508 849,373 897,030 Less: accumulated depreciation 575,959 567,992 $ 273,414 $ 329,038 Depreciation of property, plant and equipment for the years ended December 31, 2015, 2014 and 2013 was $68.2 million, $73.4 million and $57.3 million, respectively. As of December 31, 2015 and 2014, the gross book value included in machinery and equipment for internally manufactured test systems being leased by customers was $20.4 million and $89.6 million, respectively. As of December 31, 2015 and 2014, the accumulated depreciation on these test systems was $8.5 million and $19.9 million, respectively.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2015
Financial Instruments	F. FINANCIAL INSTRUMENTS Cash Equivalents Teradyne considers all highly liquid investments with maturities of three months or less at the date of acquisition to be cash equivalents. Marketable Securities Teradyne’s available-for-sale securities are classified as Level 1 and Level 2. Contingent consideration is classified as Level 3. The vast majority of Level 2 securities are fixed income securities priced by third party 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. Realized losses recorded in 2015 were $0.4 million. There were no realized losses recorded in 2014 and 2013. Realized gains recorded in 2015, 2014 and 2013 were $1.7 million, $2.4 million and $1.0 million, respectively. Realized gains are included in interest income, and realized losses are included in interest expense. Unrealized gains and losses are included in accumulated other comprehensive income (loss). The cost of securities sold is based on the specific identification method. During the years ended December 31, 2015 and 2014, there were no transfers in or out of Level 1, Level 2 or Level 3 financial instruments. 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 December 31, 2015 and 2014: December 31, 2015 Quoted Prices Significant Significant Total (in thousands) Assets Cash $ 213,336 $ — $ — $ 213,336 Cash equivalents 49,241 2,128 — 51,369 Available for sale securities: U.S. Treasury securities — 419,958 — 419,958 Corporate debt securities — 161,634 — 161,634 U.S. government agency securities — 83,952 — 83,952 Certificates of deposit and time deposits — 43,394 — 43,394 Commercial paper — 20,308 — 20,308 Equity and debt mutual funds 13,954 — — 13,954 Non-U.S. government securities — 424 — 424 Total $ 276,531 $ 731,798 $ — $ 1,008,329 Derivative assets — 109 — 109 Total $ 276,531 $ 731,907 $ — $ 1,008,438 Liabilities Contingent consideration $ — $ — $ 37,436 $ 37,436 Derivative liabilities — 146 — 146 Total $ — $ 146 $ 37,436 $ 37,582 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 262,577 $ 2,128 $ — $ 264,705 Marketable securities — 477,696 — 477,696 Long-term marketable securities 13,954 251,974 — 265,928 Prepayments — 109 — 109 $ 276,531 $ 731,907 $ — $ 1,008,438 Liabilities Other current liabilities $ — $ 146 $ — $ 146 Contingent consideration — — 15,500 15,500 Long-term contingent consideration — — 21,936 21,936 $ — $ 146 $ 37,436 $ 37,582 December 31, 2014 Quoted Prices Significant Significant Total (in thousands) Assets Cash $ 111,471 $ — $ — $ 111,471 Cash equivalents 160,218 22,567 — 182,785 Available for sale securities: U.S. Treasury securities — 402,154 — 402,154 U.S. government agency securities — 258,502 — 258,502 Corporate debt securities — 141,467 — 141,467 Commercial paper — 140,638 — 140,638 Certificates of deposit and time deposits — 49,036 — 49,036 Equity and debt mutual funds 12,333 — — 12,333 Non-U.S. government securities — 446 — 446 Total $ 284,022 $ 1,014,810 $ — $ 1,298,832 Derivative assets — 220 — 220 Total $ 284,022 $ 1,015,030 $ — $ 1,299,052 Liabilities Contingent consideration $ — $ — $ 3,350 $ 3,350 Derivative liabilities — 369 — 369 Total $ — $ 369 $ 3,350 $ 3,719 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 271,689 $ 22,567 $ — $ 294,256 Marketable securities — 533,787 — 533,787 Long-term marketable securities 12,333 458,456 — 470,789 Prepayments — 220 — 220 $ 284,022 $ 1,015,030 $ — $ 1,299,052 Liabilities Other current liabilities $ — $ 369 $ — $ 369 Contingent consideration — — 895 895 Long-term other accrued liabilities — — 2,455 2,455 $ — $ 369 $ 3,350 $ 3,719 Changes in the fair value of Level 3 contingent consideration for the years ended December 31, 2015 and 2014 were as follows: Contingent Consideration (in thousands) Balance at December 31, 2013 $ 2,230 Acquisition of AIT 1,750 Fair value adjustment of ZTEC (630 ) Balance at December 31, 2014 3,350 Acquisition of Universal Robots 31,597 Fair value adjustment of ZTEC (1,600 ) Fair value adjustment of AIT (1,250 ) Fair value adjustment of Universal Robots 5,339 Balance at December 31, 2015 $ 37,436 The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instrument: Liability December 31, Valuation Unobservable Inputs Weighted (in thousands) Contingent consideration (Universal Robots) $ 21,936 Monte Carlo Revenue for the period July 1, 2015—December 31, 2017 volatility 15% Discount Rate 5.5% Revenue for the period July 1, 2015—December 31, 2018 volatility 15% Discount Rate 5.5% Contingent consideration (AIT) $ 500 Income approach- Revenue for calendar year 2016 probability 48% Discount rate 4.7% Based on Universal Robots’ calendar 2015 EBITDA results, Teradyne will pay, in first quarter of 2016, $15 million or 100% of the eligible EBITDA contingent consideration amount. As of December 31, 2015, the significant unobservable inputs used in the Monte Carlo simulation to fair value the Universal Robots contingent consideration include forecasted revenue, revenue volatility and discount rate. Increases or decreases in the inputs would result in a higher or lower fair value measurement. The significant unobservable inputs used in the AIT fair value measurement of contingent consideration are the probabilities of successful achievement of calendar year 2016 revenue threshold and target, and a discount rate. Increases or decreases in the revenue probabilities would result in a higher or lower fair value measurement. The carrying amounts and fair values of financial instruments at December 31, 2015 and 2014 were as follows: December 31, 2015 December 31, 2014 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 264,705 $ 264,705 $ 294,256 $ 294,256 Marketable securities 743,624 743,624 1,004,576 1,004,576 Derivative assets 109 109 220 220 Liabilities Contingent consideration 37,436 37,436 3,350 3,350 Derivative liabilities 146 146 369 369 The fair values of 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 December 31, 2015 and 2014: December 31, 2015 Available-for-Sale Fair Market Cost Unrealized Unrealized Fair Market (in thousands) U.S. Treasury securities $ 421,060 $ 65 $ (1,167 ) $ 419,958 $ 379,434 Corporate debt securities 163,297 902 (2,565 ) 161,634 145,373 U.S. government agency securities 84,032 42 (122 ) 83,952 55,120 Certificates of deposit and time deposits 43,391 6 (3 ) 43,394 10,527 Commercial paper 20,298 11 (1 ) 20,308 8,646 Equity and debt mutual funds 12,996 1,119 (161 ) 13,954 2,560 Non-U.S. government securities 424 — — 424 — $ 745,498 $ 2,145 $ (4,019 ) $ 743,624 $ 601,660 Reported as follows: Cost Unrealized Unrealized Fair Market Fair Market (in thousands) Marketable securities $ 478,306 $ 38 $ (648 ) $ 477,696 $ 374,785 Long-term marketable securities 267,192 2,107 (3,371 ) 265,928 226,875 $ 745,498 $ 2,145 $ (4,019 ) $ 743,624 $ 601,660 December 31, 2014 Available-for-Sale Fair Market Cost Unrealized Unrealized Fair Market (in thousands) U.S. Treasury securities $ 402,197 $ 362 $ (405 ) $ 402,154 $ 317,771 U.S. government agency securities 258,452 135 (85 ) 258,502 104,642 Corporate debt securities 139,374 2,414 (321 ) 141,467 96,998 Commercial paper 140,616 26 (4 ) 140,638 41,747 Certificates of deposit and time deposits 49,048 11 (23 ) 49,036 20,684 Equity and debt mutual funds 10,492 1,870 (29 ) 12,333 1,234 Non-U.S. government securities 446 — — 446 — $ 1,000,625 $ 4,818 $ (867 ) $ 1,004,576 $ 583,076 Reported as follows: Cost Unrealized Unrealized Fair Market Fair Market (in thousands) Marketable securities $ 533,833 $ 99 $ (145 ) $ 533,787 $ 240,234 Long-term marketable securities 466,792 4,719 (722 ) 470,789 342,842 $ 1,000,625 $ 4,818 $ (867 ) $ 1,004,576 $ 583,076 As of December 31, 2015, the fair market value of investments with unrealized losses totaled $601.7 million. Of this value, $0.9 million had unrealized losses of $0.5 million greater than one year and $600.8 million had unrealized losses of $3.6 million for less than one year. As of December 31, 2014, the fair market value of investments with unrealized losses totaled $583.1 million. Of this value, $2.3 million had unrealized losses of $0.1 million greater than one year and $580.8 million had unrealized losses of $0.8 million for 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 December 31, 2015 and 2014, were temporary. The contractual maturities of investments held at December 31, 2015 were as follows: Cost Fair Value (in thousands) Due within one year $ 478,306 $ 477,696 Due after 1 year through 5 years 209,822 209,314 Due after 5 years through 10 years 5,183 5,179 Due after 10 years 39,191 37,481 Total $ 732,502 $ 729,670 Contractual maturities of investments held at December 31, 2015, exclude $14 million of equity and debt mutual funds as they do not have a contractual maturity date. Assets measured at fair value on a non-recurring basis as of December 31, 2014 are summarized as follows: Fair Value Measurements at Reporting Period December 31, Quoted Prices Significant Significant Total Losses (in thousands) Assets Goodwill $ 273,438 $ — $ — $ 273,438 $ 98,897 Definite lived intangible assets 158,237 — — 158,237 — Long-lived assets held and used 10,189 — 10,189 — — $ 441,864 $ — $ 10,189 $ 431,675 $ 98,897 In accordance with the provisions of ASC 350-10 , “Intangibles- Goodwill and Other 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. At December 31, 2015 and 2014, Teradyne had the following contracts to buy and sell non-U.S. currencies for U.S. dollars and other non-U.S. currencies with the following notional amounts: December 31, 2015 December 31, 2014 Buy Sell Net Buy Sell Net (in millions) Japanese Yen $ (51.9 ) $ — $ (51.9 ) $ — $ 19.7 $ 19.7 British Pound Sterling (9.5 ) — (9.5 ) — 11.7 11.7 Korean Won (5.5 ) — (5.5 ) — 4.4 4.4 Taiwan Dollar (5.0 ) — (5.0 ) (0.9 ) 5.7 4.8 Euro — 27.2 27.2 (30.6 ) — (30.6 ) Singapore Dollar — 15.0 15.0 — — — Total $ (71.9 ) $ 42.2 $ (29.7 ) $ (31.5 ) $ 41.5 $ 10.0 The fair value of the outstanding contracts was $0.0 million at December 31, 2015 and a loss of $0.1 million at December 31, 2014. In 2015 and 2014, Teradyne recorded net realized losses related to foreign currency forward contracts hedging net monetary assets and liabilities of $3.0 million and $0.2 million, respectively. In 2013, Teradyne recorded net realized gains related to foreign currency forward contracts hedging net monetary assets and liabilities of $5.9 million. Gains and losses on foreign currency forward contracts and foreign currency remeasurement gains and losses on monetary assets and liabilities are included in other (income) expense, net. The following table summarizes the fair value of derivative instruments as of December 31, 2015 and 2014: Balance Sheet Location December 31, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 109 $ 220 Foreign exchange contracts Other current liabilities (146 ) (369 ) Total derivatives $ (37 ) $ (149 ) The following table summarizes the effect of derivative instruments in the statement of operations recognized for the years ended December 31, 2015, 2014 and 2013. The table does not reflect the corresponding gains and losses from the remeasurement of the monetary assets and liabilities denominated in foreign currencies. For the years ended December 31, 2015, 2014, and 2013, gains (losses) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $2.5 million, $(0.9) million, and $(6.9) million, respectively. Location of Losses (Gains) December 31, December 31, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ 3,047 $ 237 $ (5,933 ) Total derivatives $ 3,047 $ 237 $ (5,933 ) See Note G: “Debt” regarding derivatives related to the convertible senior notes. Concentration of Credit Risk Financial instruments which potentially subject Teradyne to concentrations of credit risk consist principally of cash equivalents, marketable securities, forward currency contracts and accounts receivable. Teradyne’s cash equivalents consist primarily of money market funds invested in U.S. Treasuries and government agencies. Teradyne’s fixed income available-for-sale marketable securities have a minimum rating of AA by one or more of the major credit rating agencies. Teradyne places foreign currency forward contracts with high credit-quality financial institutions in order to minimize credit risk exposure. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of geographically dispersed customers. Teradyne performs ongoing credit evaluations of its customers’ financial condition and from time to time may require customers to provide a letter of credit from a bank to secure accounts receivable. One customer comprised 10% or more of Teradyne’s accounts receivable balance as of December 31, 2015. A different customer comprised 10% or more of Teradyne’s accounts receivable balance as of December 31, 2014. Equity Interest On November 1, 2013, in connection with the acquisition of Empirix, Inc. by Thoma Bravo LLC, Teradyne sold its equity interest in Empirix, Inc., a private company, and received cash proceeds of $34.2 million which was recorded as a gain in other (income) expense, net. An additional $5.4 million of cash proceeds that was held in escrow for 15 months, for potential indemnifications to the buyer, was paid to Teradyne in February 2015 and it was recorded as a gain in other (income) expense, net in the first quarter of 2015.

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt	G. DEBT Revolving Credit Facility On April 27, 2015, Teradyne entered into a Credit Agreement (the “Credit Agreement”) with Barclays Bank PLC, as administrative agent and collateral agent, and the lenders party thereto. The Credit Agreement provides for a five-year, senior secured revolving credit facility of up to $350 million (the “Credit Facility”). The Credit Agreement further provides that, subject to customary conditions, Teradyne may seek to obtain from existing or new lenders incremental commitments under the Credit Facility in an aggregate principal amount not to exceed $150 million. Proceeds from the Credit Facility may be used for general corporate purposes and working capital. Teradyne incurred $2.3 million in costs related to the revolving credit facility. These costs are being amortized over the five year term of the revolving credit facility and are included in interest expense in the statement of operations. As of February 29, 2016, Teradyne has not borrowed any funds under the Credit Facility. The interest rates applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.00% to 1.00% per annum or LIBOR plus a margin ranging from 1.00% to 2.00% per annum, based on the Consolidated Leverage Ratio of Teradyne and its Restricted Subsidiaries. In addition, Teradyne will pay a commitment fee on the unused portion of the commitments under the Credit Facility ranging from 0.125% to 0.350% per annum, based on the then applicable Consolidated Leverage Ratio. Teradyne is not required to repay any loans under the Credit Facility prior to maturity, subject to certain customary exceptions. Teradyne is permitted to prepay all or any portion of the loans under the Credit Facility prior to maturity without premium or penalty, other than customary LIBOR breakage costs. The Credit Agreement contains customary events of default, representations, warranties and affirmative and negative covenants that, among other things, limit Teradyne’s and its Restricted Subsidiaries’ ability to sell assets, grant liens on assets, incur other secured indebtedness and make certain investments and restricted payments, all subject to exceptions set forth in the Credit Agreement. The Credit Agreement also requires Teradyne to satisfy two financial ratios measured as of the end of each fiscal quarter: a consolidated leverage ratio and an interest coverage ratio. As of December 31, 2015, Teradyne was in compliance with all covenants. The Credit Facility is guaranteed by certain of Teradyne’s domestic subsidiaries and collateralized by assets of Teradyne and such subsidiaries, including a pledge of 65% of the capital stock of certain foreign subsidiaries. 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. had guaranteed payment of the loan obligation. The principal was amortized over the term of the loan with semi-annual principal payments of approximately $1 million payable on September 30 and March 30 each year. The final principal and interest payments were made in March 2014. Convertible Senior Notes On March 31, 2009, Teradyne entered into an underwriting agreement regarding a public offering of $175.0 million aggregate principal amount of 4.50% convertible senior notes due March 15, 2014 (the “Notes”). On April 1, 2009, the underwriters exercised their option to purchase an additional $15.0 million aggregate principal amount of the Notes for a total aggregate principal amount of $190.0 million. The Notes bore interest at a rate of 4.50% per annum, payable semi-annually in arrears on March 15 and September 15 of each year, beginning on September 15, 2009. 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, being the fixed number specified in the Notes purchase agreement, less 50.7 shares). The 50.7 shares were determined, as specified in the Notes purchase agreement, 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 Teradyne retired. From June 17, 2014 to September 17, 2014, the hedge counterparty exercised its warrant agreement entered into with Teradyne at the time of issuance of the Notes. The warrants were net share settled. In 2014, Teradyne issued 21.2 million shares of its common stock for warrants exercised at a weighted average strike price of $7.6348 per share. For the year ended December 31, December 31, (in thousands) Contractual interest expense on the coupon $ — $ 1,757 Amortization of the discount component and debt issue fees recognized as interest expense — 4,493 Total interest expense on the convertible debt $ — $ 6,250

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2015
Accumulated Other Comprehensive Income	H. ACCUMULATED OTHER COMPREHENSIVE INCOME Changes in accumulated other comprehensive income, which is presented net of tax, consists of the following: Foreign Unrealized Retirement Total (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 $1,449 — 2,417 — 2,417 Amounts reclassified from accumulated other comprehensive income, net of tax of $(645), $(169) — (1,433 ) (295 ) (1,728 ) Net current period other comprehensive income, net of tax of $804, $(169) — 984 (295 ) 689 Balance at December 31, 2014, net of tax of $1,598, $(453) $ — $ 2,365 $ 2,324 $ 4,689 Other comprehensive loss before reclassifications, net of tax of $0, $(1,667) (8,759 ) (3,075 ) — (11,834 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $(390), $(169) — (704 ) (295 ) (999 ) Net current period other comprehensive loss, net of tax of $0, $(2,057), $(169) (8,759 ) (3,779 ) (295 ) (12,833 ) Balance at December 31, 2015, net of tax of $0, $(459), $(622) $ (8,759 ) $ (1,414 ) $ 2,029 $ (8,144 ) Reclassifications out of accumulated other comprehensive income to the statement of operations for the years ended December 31, 2015, 2014 and 2013, were as follows: Details about Accumulated Other Comprehensive Income Components For the year ended Affected Line Item December 31, December 31, December 31, (in thousands) Available-for-sale marketable securities Unrealized gains, net of tax of $390, $645, $257 $ 704 $ 1,433 $ 447 Interest income Amortization of defined benefit pension and postretirement plans Prior service benefit, net of tax of $169, $169, $159 $ 295 $ 295 $ 276 (a) Total reclassifications, net of tax of $559, $814, $416 $ 999 $ 1,728 $ 723 Net income (a) The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note M: “Retirement Plans.”

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets	I. GOODWILL AND INTANGIBLE ASSETS Goodwill Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, “Intangibles—Goodwill and Other” Teradyne has the option to perform a qualitative assessment (“Step zero”) to determine whether it is more-likely-than-not that the fair value of a reporting unit is less than its carrying amount. If Teradyne determines this is the case, Teradyne is required to perform the two-step goodwill impairment test to identify potential goodwill impairment and measure the amount of goodwill impairment loss to be recognized. If Teradyne determines that it is more-likely-than-not that the fair value of the reporting unit is greater than its carrying amounts, the two-step goodwill impairment test is not required. When performing the two-step process, the first step involves a comparison of the estimated fair value of a reporting unit to its carrying amount, including goodwill. In performing the first step, Teradyne determines the fair value of a reporting unit using the results derived from an income approach and a market approach. The income approach is estimated through the discounted cash flow (“DCF”) analysis. Determining fair value requires the exercise of significant judgment, including judgments about appropriate discount rates, perpetual growth rates, and the amount and timing of expected future cash flows. Discount rates are based on a weighted average cost of capital (“WACC”), which represents the average rate a business must pay its providers of debt and equity, plus a risk premium. The WACC used to test goodwill is derived from a group of comparable companies. The cash flows employed in the DCF analysis are derived from internal forecasts and external market forecasts. The market approach estimates the fair value of the reporting unit by utilizing the market comparable method which is based on revenue and earnings multiples from comparable companies. If the estimated fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired and the second step of the impairment test is not necessary. If the carrying amount of a reporting unit exceeds its estimated fair value, then the second step of the goodwill impairment test must be performed. The second step of the goodwill impairment test compares the implied fair value of the reporting unit’s goodwill with its carrying amount of goodwill to measure the amount of impairment loss, if any. The implied fair value of goodwill is determined in the same manner as the amount of goodwill recognized in a business combination, whereby the estimated fair value of the reporting unit is allocated to all of the assets and liabilities of that unit (including any unrecognized intangible assets) as if the reporting unit had been acquired in a business combination and the fair value of the reporting unit was the purchase price paid. If the carrying amount of the reporting unit’s goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to that excess. In 2015, Teradyne performed step one of the two step impairment test for the Wireless Test and Defense/Aerospace reporting units and the Step zero assessment for the Industrial Automation reporting unit. In 2015, there was no impairment. In 2014, as a result of decreased projected demand attributable to an estimated smaller future wireless test market due to reuse of wireless test equipment, price competition and different testing techniques, Teradyne determined that for its Wireless Test reporting unit, the carrying amount of its net assets exceeded its respective fair value, indicating that a potential impairment existed. After completing the second step of the goodwill impairment test, Teradyne recorded a $98.9 million goodwill impairment charge in the fourth quarter of 2014. The fourth quarter 2014 goodwill impairment test of Teradyne’s Defense/Aerospace reporting unit, which is included in Teradyne’s System Test reportable segment, did not identify any goodwill impairment. The fourth quarter 2013 goodwill impairment test of Teradyne’s Wireless Test reporting unit did not identify any goodwill impairment. The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2015 and 2014 are as follows: Wireless Industrial System Semiconductor Total (in thousands) Balance at December 31, 2013: Goodwill $ 361,792 $ — $ 148,183 $ 260,540 $ 770,515 Accumulated impairment losses — — (148,183 ) (260,540 ) (408,723 ) ZTEC adjustment 27 — — — 27 AIT acquisition — — 10,516 — 10,516 Balance at December 31, 2014: Goodwill 361,819 — 158,699 260,540 781,058 Accumulated impairment losses (98,897 ) — (148,183 ) (260,540 ) (507,620 ) Universal Robots acquisition — 221,128 — — 221,128 Foreign currency translation adjustment — (6,153 ) — — (6,153 ) Balance at December 31, 2015: Goodwill 361,819 214,975 158,699 260,540 996,033 Accumulated impairment losses (98,897 ) — (148,183 ) (260,540 ) (507,620 ) $ 262,922 $ 214,975 $ 10,516 $ — $ 488,413 Intangible Assets Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets: December 31, 2015 Gross Accumulated Net Weighted (in thousands) Developed technology $ 379,778 $ 220,306 $ 159,472 6.0 years Customer relationships 110,340 63,718 46,622 7.9 years Tradenames and trademarks 52,396 18,879 33,517 9.5 years Non-compete agreement 320 100 220 4.0 years Customer backlog 170 170 — 0.3 years Total intangible assets $ 543,004 $ 303,173 $ 239,831 6.7 years December 31, 2014 Gross Accumulated Net Weighted (in thousands) Developed technology $ 345,513 $ 224,059 $ 121,454 6.2 years Customer relationships 146,635 93,998 52,637 7.7 years Tradenames and trademarks 30,414 14,205 16,209 9.0 years Non-compete agreement 320 20 300 4.0 years Customer backlog 170 170 — 0.3 years Total intangible assets $ 523,052 $ 332,452 $ 190,600 6.8 years During the year ended December 31, 2015, Teradyne recorded intangible assets in the amount of $121.6 million related to its Universal Robots acquisition and Teradyne wrote off $98.2 million of fully amortized intangible assets. During the year ended December 31, 2014, Teradyne recorded intangible assets in the amount of $9.1 million related to its AIT acquisition. Aggregate intangible assets amortization expense for the years ended December 31, 2015, 2014 and 2013 was $69.0 million, $70.8 million, and $72.4 million, respectively. Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2016 $ 79,874 2017 71,133 2018 44,464 2019 23,611 2020 9,990 Thereafter 10,759

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies	J. COMMITMENTS AND CONTINGENCIES Purchase Commitments As of December 31, 2015, Teradyne had entered into non-cancelable purchase commitments for certain components and materials. The purchase commitments covered by the agreements aggregate to approximately $237.0 million, of which $230.3 million is for less than one year. Commitments Teradyne leases certain of its office buildings and other facilities under various operating lease arrangements that include renewal options and escalation clauses for adjusting rent payments to reflect changes in price indices. Rental expense for leases with fixed escalation clauses is recognized on a straight line basis over the lease term. Rental expense for the years ended December 31, 2015, 2014 and 2013 was $15.9 million, $16.0 million and $16.5 million, respectively. The following table reflects Teradyne’s non-cancelable operating lease commitments: Non-cancelable (in thousands) 2016 $ 15,665 2017 11,778 2018 9,559 2019 8,487 2020 7,222 Beyond 2021 16,009 Total $ 68,720 Legal Claims Teradyne is subject to legal proceedings, claims and investigations that arise in the ordinary course of business such as, but not limited to, patent, employment, commercial and environmental matters. Teradyne believes that it has meritorious defenses against all pending claims and intends to vigorously contest them. While it is not possible to predict or determine the outcomes of any pending claims or to provide possible ranges of losses that may arise, Teradyne believes the potential losses associated with all of these actions are unlikely to have a material adverse effect on its business, financial position or results of operations. Guarantees and Indemnification Obligations Teradyne provides indemnification, to the extent permitted by law, to its officers, directors, employees and agents for liabilities arising from certain events or occurrences while the officer, director, employee, or agent, is or was serving, at Teradyne’s request in such capacity. Teradyne has entered into indemnification agreements with certain of its officers and directors. With respect to acquisitions, Teradyne provides indemnifications to or assumes indemnification obligations for the current and former directors, officers and employees of the acquired companies in accordance with the acquired companies’ by-laws and charter. As a matter of practice, Teradyne has maintained directors’ and officers’ liability insurance coverage including coverage for directors and officers of acquired companies. Teradyne enters into agreements in the ordinary course of business with customers, resellers, distributors, integrators and suppliers. Most of these agreements require Teradyne to defend and/or indemnify the other party against intellectual property infringement claims brought by a third party with respect to Teradyne’s products. From time to time, Teradyne also indemnifies customers and business partners for damages, losses and liabilities they may suffer or incur relating to personal injury, personal property damage, product liability, breach of confidentiality obligations and environmental claims relating to the use of Teradyne’s products and services or resulting from the acts or omissions of Teradyne, its employees, authorized agents or subcontractors. On occasion, Teradyne has also provided guarantees to customers regarding the delivery and performance of its products in addition to the warranty described below. As a matter of ordinary business course, Teradyne warrants that its products will substantially perform in accordance with its standard published specifications in effect at the time of delivery. Most warranties have a one year duration commencing from installation. A provision is recorded upon revenue recognition to cost of revenue for estimated warranty expense based upon historical experience. When Teradyne receives revenue for extended warranties beyond the standard duration, it is deferred and recognized on a straight line basis over the contract period. Related costs are expensed as incurred. As of December 31, 2015 and 2014, Teradyne had a product warranty accrual of $6.9 million and $8.9 million, respectively, included in other accrued liabilities, and revenue deferrals related to extended warranties of $46.5 million and $43.3 million, respectively, included in short and long-term deferred revenue and customer advances. In addition, and in the ordinary course of business, Teradyne provides minimum purchase guarantees to certain vendors to ensure continuity of supply against the market demand. Although some of these guarantees provide penalties for cancellations and/or modifications to the purchase commitments as the market demand decreases, most of the guarantees do not. Therefore, as the market demand decreases, Teradyne re-evaluates these guarantees and determines what charges, if any, should be recorded. With respect to its agreements covering product, business or entity divestitures and acquisitions, Teradyne provides certain representations, warranties and covenants to purchasers and agrees to indemnify and hold such purchasers harmless against breaches of such representations, warranties and covenants. Many of the indemnification claims have a definite expiration date while some remain in force indefinitely. With respect to its acquisitions, Teradyne may, from time to time, assume the liability for certain events or occurrences that took place prior to the date of acquisition. As a matter of ordinary course of business, Teradyne occasionally guarantees certain indebtedness obligations of its subsidiary companies, limited to the borrowings from financial institutions, purchase commitments to certain vendors, and lease commitments to landlords. Based on historical experience and information known as of December 31, 2015 and 2014, except for product warranty, Teradyne has not recorded any liabilities for these guarantees and obligations because the amount would be immaterial.

Net Income per Common Share

Net Income per Common Share	12 Months Ended
	Dec. 31, 2015
Net Income per Common Share	K. NET INCOME PER COMMON SHARE The following table sets forth the computation of basic and diluted net income per common share: 2015 2014 2013 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 206,477 $ 81,272 $ 164,947 Weighted average common shares-basic 211,544 202,908 190,772 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) — 5,013 23,341 Convertible note hedge warrant shares (2) — 12,562 18,795 Restricted stock units 1,130 1,092 1,127 Stock options 606 944 1,528 Employee stock purchase rights 41 31 36 Dilutive potential common shares 1,777 19,642 44,827 Weighted average common shares-diluted 213,321 222,550 235,599 Net income per common share-basic $ 0.98 $ 0.40 $ 0.86 Net income per common share-diluted $ 0.97 $ 0.37 $ 0.70 (1) Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $5.48, 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. (2) Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.67, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne’s call option on its common stock (convertible note hedge transaction) was excluded from the calculation of diluted shares because the effect was anti-dilutive. See Note G: “Debt” regarding the convertible note hedge transaction. The computation of diluted net income per common share for 2015 excludes the effect of the potential exercise of stock options to purchase approximately 0.2 million shares because the effect would have been anti-dilutive. The computation of diluted net income per common share for 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 2013 excludes the effect of the potential exercise of stock options to purchase approximately 0.4 million shares because the effect would have been anti-dilutive.

Restructuring and Other

Restructuring and Other	12 Months Ended
	Dec. 31, 2015
Restructuring and Other	L. RESTRUCTURING AND OTHER Other During the year ended December 31, 2015, Teradyne recorded $3.6 million of other charges of which $5.3 million was an expense for the increase in the fair value of the Universal Robots contingent consideration liability and $1.0 million for acquisition costs related to Universal Robots, partially offset by a $2.9 million gain from fair value adjustments to decrease the acquisition contingent consideration liability related to ZTEC, $1.6 million, and AIT, $1.3 million. During the year ended December 31, 2014, Teradyne recorded a $0.6 million gain from the fair value adjustment to decrease the ZTEC acquisition contingent consideration, partially offset by $0.4 million of acquisition costs related to AIT. Restructuring During the year ended December 31, 2015, Teradyne recorded $1.5 million of severance charges related to headcount reductions of 23 people, primarily in System Test and Semiconductor Test. During the year ended December 31, 2014, Teradyne recorded $1.6 million of severance charges related to headcount reductions of approximately 43 people, primarily in Semiconductor Test and Wireless Test. During the year ended December 31, 2013, Teradyne recorded $1.9 million of severance charges related to headcount reductions of 48 people primarily in System Test and Semiconductor Test and a $(0.4) million credit in Corporate related to a change in the estimated exit costs related to a leased facility. The remaining accrual for severance of $0.4 million is reflected in the accrued employees’ compensation and withholdings on the balance sheet and is expected to be paid by March 2016.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2015
Retirement Plans	M. RETIREMENT PLANS ASC 715, “Compensation—Retirement Benefits” 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 the 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 (the “IRC”), as well as unfunded qualified foreign plans. The December 31 balances of these defined benefit pension plans assets and obligations are shown below: 2015 2014 United States Foreign United States Foreign (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 367,619 $ 58,210 $ 293,912 $ 52,182 Service cost 2,462 1,006 2,218 897 Interest cost 13,142 1,444 12,875 1,837 Actuarial (gain) loss (13,221 ) 7,498 72,596 8,975 Benefits paid (18,885 ) (859 ) (13,982 ) (1,265 ) Curtailment — (634 ) — — Plan participants’ contributions — 64 — 88 Non-U.S. currency movement — (4,439 ) — (4,504 ) End of year 351,117 62,290 367,619 58,210 Change in plan assets: Fair value of plan assets: Beginning of year 316,072 29,511 256,373 25,756 Company contributions 10,517 808 31,753 1,168 Plan participants’ contributions — 64 — 88 Actual return on plan assets (9,300 ) (136 ) 41,928 5,192 Benefits paid (18,885 ) (859 ) (13,982 ) (1,265 ) Admin expenses paid — (43 ) — — Non-U.S. currency movement — (1,204 ) — (1,428 ) End of year 298,404 28,141 316,072 29,511 Funded status $ (52,713 ) $ (34,149 ) $ (51,547 ) $ (28,699 ) The following table provides amounts recorded within the account line items of the statement of financial position as of December 31: 2015 2014 United Foreign United Foreign (in thousands) Retirement plans assets $ 636 $ — $ 3,090 $ 9,806 Accrued employees’ compensation and withholdings (2,564 ) (695 ) (2,492 ) (906 ) Retirement plans liabilities (50,785 ) (33,454 ) (52,145 ) (37,599 ) Funded status $ (52,713 ) $ (34,149 ) $ (51,547 ) $ (28,699 ) The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2015 2014 United States Foreign United States Foreign (in thousands) Prior service cost, before tax $ 224 $ — $ 358 $ — Deferred taxes 479 — 429 — Total recognized in other comprehensive income, net of tax $ 703 $ — $ 787 $ — The estimated portion of prior service cost remaining in accumulated other comprehensive income that is expected to be recognized as a component of net periodic pension cost in 2016 is $0.1 million. The accumulated benefit obligation for the United States defined benefit pension plans was $340.1 million and $357.0 million at December 31, 2015 and 2014, respectively. The accumulated benefit obligation for foreign defined benefit pension plans was $56.6 million and $49.8 million at December 31, 2015 and 2014, respectively. Information for pension plans with an accumulated benefit obligation in excess of plan assets as of December 31: 2015 2014 United States Foreign United States Foreign (in millions) Projected benefit obligation $ 53.3 $ 35.2 $ 54.6 $ 39.5 Accumulated benefit obligation 47.3 29.5 48.5 32.7 Fair value of plan assets — 1.0 — 1.0 Expense For the years ended December 31, 2015, 2014 and 2013, Teradyne’s net periodic pension cost (income) was comprised of the following: 2015 2014 2013 United Foreign United Foreign United Foreign (in thousands) Components of Net Periodic Pension Cost (Income): Service cost $ 2,462 $ 1,006 $ 2,218 $ 897 $ 2,393 $ 1,034 Interest cost 13,142 1,444 12,875 1,837 11,318 1,948 Expected return on plan assets (14,517 ) (781 ) (12,500 ) (868 ) (13,632 ) (959 ) Amortization of prior service cost 134 — 135 — 164 — Net actuarial loss (gain) 10,596 8,415 43,168 4,651 (7,063 ) (1,252 ) Curtailment — (634 ) — — — — Total net periodic pension cost (income) $ 11,817 $ 9,450 $ 45,896 $ 6,517 $ (6,820 ) $ 771 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service cost (134 ) — (135 ) — (164 ) — Total recognized in other comprehensive income (134 ) — (135 ) — (164 ) — Total recognized in net periodic pension cost (income) and other comprehensive income $ 11,683 $ 9,450 $ 45,761 $ 6,517 $ (6,984 ) $ 771 Weighted Average Assumptions to Determine Net Periodic Pension Cost at January 1: 2015 2014 2013 United States Foreign United States Foreign United States Foreign Discount rate 3.7 % 2.6 % 4.5 % 3.8 % 3.6 % 3.7 % Expected return on plan assets 4.8 2.6 5.0 3.4 5.0 3.7 Salary progression rate 2.9 3.2 3.0 3.5 3.0 3.5 Weighted Average Assumptions to Determine Pension Obligations at December 31: 2015 2014 United States Foreign United States Foreign Discount rate 4.0 % 2.3 % 3.7 % 2.6 % Salary progression rate 2.7 3.2 2.9 3.2 In developing the expected return on plan assets assumption, Teradyne evaluates input from its investment manager and pension consultants, including their review of asset class return expectations. Based on this review, Teradyne believes that 4.8% was an appropriate rate to use for fiscal 2015 for the U.S. Qualified Pension Plan (“U.S. Plan”). Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans. The discount rate utilized to determine future pension obligations for the U.S. Plan is based on Citigroup Pension Index adjusted for the plan’s expected cash flows and was 4.0% at December 31, 2015, up from 3.7% at December 31, 2014. Plan Assets As of December 31, 2015, the fair value of Teradyne’s pension plans’ assets totaled $326.6 million of which $298.4 million was related to the U.S. Plan, $27.1 million was related to the U.K. defined benefit pension plan, and $1.0 million was related to the Taiwan defined benefit pension plan. Substantially all Teradyne’s pension plans’ assets are held in individual trusts, which were established for the investment of assets of Teradyne’s sponsored retirement plans. Teradyne’s weighted average pension asset allocation at December 31, 2015 and 2014, by asset category is as follows: 2015 2014 United States Foreign United States Foreign Fixed income securities 88.6 % — % 83.3 % 77.3 % Equity securities 9.8 — 15.4 19.0 Other 1.6 100.0 1.3 3.7 100.0 % 100.0 % 100.0 % 100.0 % The assets of the U.S. Plan are overseen by the Teradyne Fiduciary Committee which is comprised of members of senior management drawn from appropriate diversified levels of the management team. The Fiduciary Committee is responsible for setting the policy that provides the framework for management of the U.S. Plan assets. In accordance with its responsibilities, the Fiduciary Committee meets on a regular basis to review the performance of the U.S. Plan assets and compliance with the investment policy. The policy sets forth an investment structure for managing U.S. Plan assets, including setting the asset allocation ranges, which are expected to provide an appropriate level of overall diversification required to maximize the long-term return on plan assets for a prudent and reasonable level of risk given prevailing market conditions, total investment return over the long term, and preservation of capital, while maintaining sufficient liquidity to pay the benefits of the U.S. Plan. The investment portfolio will not, at any time, have a direct investment in Teradyne stock. It may have indirect investment in Teradyne stock, if one of the funds selected by the investment manager invests in Teradyne stock. In developing the asset allocation ranges, third party asset allocation studies are periodically performed that consider the current and expected positions of the plan assets and funded status. Based on this study and other appropriate information, the Fiduciary Committee establishes asset allocation ranges taking into account acceptable risk targets and associated returns. The investment return objectives are to avoid excessive volatility and produce a rate of return that at least matches the Policy Index identified below. The manager’s investment performance is reviewed at least annually. Results for the total portfolio and for each major category of assets are evaluated in comparison with appropriate market indices and the Policy Index. The target asset allocation and the index for each asset category for the U.S. Plan, per the investment policy, are as follows: Asset Category: Policy Index: Target U.S. corporate fixed income Barclays U.S. Corporate A or Better Index 76 % Global equity MSCI World Minimum Volatility Index 10 U.S. government fixed income Barclays U.S. Long Government Bond Index 8 High yield fixed income Barclays U.S. Corporate High Yield 2% Issuer Cap Index 5 Cash Citigroup Three Month U.S. Treasury Bill Index 1 Teradyne’s U.S. Plan invests primarily in common trust funds. Units held in the common trust funds are valued at the unit price as reported by the investment manager based on the asset value of the underlying investments; underlying investments in equity securities are valued at the last reported sales price, and underlying investments in fixed-income securities are generally valued using methods based upon market transactions for comparable securities. In the fourth quarter of 2015, the Trustees of the U.K. defined benefit pension plan purchased group annuity insurance contracts. The cash flows from the contracts are intended to match the plan’s obligations. During the years ended December 31, 2015 and 2014, there were no transfers of pension assets in or out of Level 1, Level 2 or Level 3. The fair value of pension plan assets by asset category and by level at December 31, 2015 and December 31, 2014 were as follows: December 31, 2015 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 240,695 $ — $ 240,695 $ — $ — $ — $ — U.S. government securities — 23,761 — 23,761 — — — — Global equity — 29,193 — 29,193 — — — — Group annuity insurance contracts — — 2,982 2,982 — — 26,410 26,410 Other — — — — — 1,029 — 1,029 Cash and cash equivalents 1,773 — — 1,773 702 — — 702 Total $ 1,773 $ 293,649 $ 2,982 $ 298,404 $ 702 $ 1,029 $ 26,410 $ 28,141 December 31, 2014 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 193,741 $ — $ 193,741 $ — $ — $ — $ — U.S. government securities — 65,830 — 65,830 — — — — U.K. government securities — — — — — 22,811 — 22,811 Asset backed securities — 3,747 — 3,747 — — — — U.S. equity (large cap) — 33,970 — 33,970 — — — — International equity — 14,631 — 14,631 — 5,610 — 5,610 Group annuity insurance contracts — — 2,990 2,990 — — — — Other — 65 — 65 — 957 — 957 Cash and cash equivalents 1,098 — — 1,098 133 — — 133 Total $ 1,098 $ 311,984 $ 2,990 $ 316,072 $ 133 $ 29,378 $ — $ 29,511 The pension plan assets identified as level 3 above are related to group annuity insurance contracts held by the U.K. defined benefit pension plan and the U.S. Plan. The fair value of these assets was calculated using the present value of future pension payments due under the group annuity insurance contracts. The table below indicates the change in value related to these level 3 assets during 2015 and 2014: Group Annuity Insurance Contracts (in thousands) Balance at December 31, 2013 $ 2,985 Interest and market value adjustments 152 Benefits paid (125 ) Other (22 ) Balance at December 31, 2014 $ 2,990 Purchases of group annuity insurance contracts 27,313 Interest and market value adjustments (825 ) Benefits paid (67 ) Other (19 ) Balance at December 31, 2015 $ 29,392 Contributions Teradyne’s funding policy is to make contributions to the plans in accordance with local laws and to the extent that such contributions are tax deductible. During 2015, Teradyne contributed $8.0 million to the U.S Plan, $2.5 million to the U.S. supplemental executive defined benefit pension plan and $0.8 million to certain qualified plans for non-U.S. subsidiaries. During 2014, Teradyne contributed $30.0 million to the U.S Plan, $1.8 million to the U.S. supplemental executive defined benefit pension plan and $1.2 million to certain qualified plans for non-U.S. subsidiaries. In 2016, contributions to the U.S. supplemental executive defined benefit pension plan and non U.S. plans will be approximately $2.6 million and $0.8 million, respectively. Teradyne does not expect to make any contributions to the U.S. Plan in 2016. Expected Future Pension Benefit Payments Future benefit payments are expected to be paid as follows: United States Foreign (in thousands) 2016 $ 19,696 $ 1,062 2017 18,346 1,032 2018 18,836 1,021 2019 19,453 1,477 2020 20,129 1,266 2021-2025 109,860 8,561 Postretirement Benefit Plans 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 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. The December 31 balances of the postretirement assets and obligations are shown below: 2015 2014 (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 7,162 $ 9,019 Service cost 48 59 Interest cost 237 335 Actuarial (gain) loss (648 ) (1,255 ) Benefits paid (769 ) (996 ) End of year 6,030 7,162 Change in plan assets: Fair value of plan assets: Beginning of year — — Company contributions 769 996 Benefits paid (769 ) (996 ) End of year — — Funded status $ (6,030 ) $ (7,162 ) The following table provides amounts recorded within the account line items of financial position as of December 31: 2015 2014 (in thousands) Accrued employees’ compensation and withholdings $ (692 ) $ (780 ) Retirement plans liability (5,338 ) (6,382 ) Funded status $ (6,030 ) $ (7,162 ) The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2015 2014 (in thousands) Prior service credit, before tax $ (1,632 ) $ (2,230 ) Deferred taxes (1,100 ) (882 ) Total recognized in other comprehensive income, net of tax $ (2,732 ) $ (3,112 ) The estimated portion of prior service credit remaining in accumulated other comprehensive income that is expected to be recognized as a component of net periodic postretirement benefit (income) expense in 2016 is $(0.6) million. Expense For the years ended December 31, 2015, 2014 and 2013, Teradyne’s net periodic postretirement benefit income was comprised of the following: 2015 2014 2013 (in thousands) Components of Net Periodic Postretirement Benefit Income: Service cost $ 48 $ 59 $ 75 Interest cost 237 335 342 Amortization of prior service credit (598 ) (598 ) (598 ) Net actuarial gain (648 ) (1,255 ) (2,025 ) Total net periodic postretirement benefit income (961 ) (1,459 ) (2,206 ) Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service credit 598 598 598 Total recognized in other comprehensive income 598 598 598 Total recognized in net periodic postretirement benefit income and other comprehensive income $ (363 ) $ (861 ) $ (1,608 ) Weighted Average Assumptions to Determine Net Periodic Postretirement Benefit Income as of January 1: 2015 2014 2013 Discount rate 3.5 % 4.1 % 3.1 % Initial health care cost trend rate 7.5 8.0 8.5 Ultimate health care cost trend rate 5.0 5.0 5.0 Year in which ultimate health care cost trend rate is reached 2022 2020 2020 Weighted Average Assumptions to Determine Postretirement Benefit Obligation as of December 31: 2015 2014 2013 Discount rate 3.9 % 3.5 % 4.1 % Initial medical trend 7.5 7.5 8.0 Ultimate health care trend 5.0 5.0 5.0 Medical cost trend rate decrease to ultimate rate in year 2023 2022 2020 Assumed health care trend rates could have a significant effect on the amounts reported for health care plans. A one percentage point change in the assumed health care cost trend rates for the year ended December 31, 2015, would have the following effects: 1 Percentage 1 Percentage (in thousands) Effect on total service and interest cost components $ 3 $ (2 ) Effect on postretirement benefit obligations 59 (56 ) Expected Future Benefit Payments Future benefit payments are expected to be paid as follows: Benefit Payments (in thousands) 2016 $ 692 2017 587 2018 553 2019 492 2020 410 2021-2025 1,654

Stock Based Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2015
Stock Based Compensation	N. STOCK-BASED COMPENSATION Stock Compensation Plans At Teradyne’s annual meeting of stockholders held May 21, 2013, Teradyne’s stockholders approved an amendment to Teradyne’s 2006 Equity and Cash Compensation Incentive Plan to increase the number of shares issuable by 10.0 million for an aggregate of 32.0 million shares issuable thereunder. Teradyne’s stockholders also approved an amendment to Teradyne’s 1996 Employee Stock Purchase Plan to increase the number of shares issuable by 5.0 million, for an aggregate of 30.4 million shares issuable thereunder. Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Stock options to purchase Teradyne’s common stock at 100% of the fair market value on the grant date vest in equal annual installments over four years from the grant date and have a maximum term of seven years. Time-based restricted stock unit awards granted to employees vest in equal annual installments over four years. Restricted stock unit awards granted to non-employee directors vest after a one year period, with 100% of the award vesting on the first anniversary of the grant date. Teradyne expenses the cost of the restricted stock unit awards subject to time-based vesting, which is determined to be the fair market value of the shares at the date of grant, ratably over the period during which the restrictions lapse. For grants prior to January 2014, performance-based restricted stock units (“PRSUs”) granted to executive officers were subject to time-based vesting and performance-based vesting. The percentage level of performance satisfied for performance-based grants was assessed on or near the anniversary of the grant date and, in turn, that percentage level determined the number of performance-based restricted stock units available for vesting over a four-year vesting period; portions of the performance-based grants not available for vesting were forfeited. Commencing in January 2014, Teradyne granted 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. The TSR PRSUs will vest upon the three-year anniversary of the grant date. No TSR PRSUs will vest if the executive officer is no longer an employee at the end of the three-year period. Beginning with PRSUs granted in January 2014, if the recipient’s employment ends prior to the determination of the performance percentage due to (1) permanent disability or death or (2) retirement or termination other than for cause, after attaining both at least age sixty and at least ten years of service, then the recipient’s PRSUs (based on the actual performance percentage achieved on the determination date) will vest on the date the performance percentage is determined. 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 at any time during the three-year service period the executive officer is no longer an employee, subject to the retirement and termination eligibility provisions noted above. During 2015 and 2014, Teradyne granted 0.2 million and 0.1 million TSR PRSUs, respectively, with a grant date fair value of $18.21 and $22.06, respectively. The fair value was estimated using the Monte Carlo simulation model with the following assumptions: 2015 2014 Risk-free interest rate 0.77 % 0.75 % Teradyne volatility-historical 28.2 % 36.1 % Philadelphia Semiconductor Index volatility-historical 19.7 % 24.6 % Dividend yield 1.33 % 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 for 2015 and 2014 was based upon an estimated annual dividend amount of $0.24 per share divided by Teradyne’s stock price on the grant date of $18.10 for 2015 grants and $19.16 for 2014 grants. Stock Options Valuation Assumptions: The total number of stock options granted in 2015, 2014 and 2013 were 0.1 million, 0.1 million and 0.2 million, respectively, at the weighted average grant date fair value of $4.43, $5.49 and $6.09 per share, respectively. The fair value of the stock options at grant date was estimated using the Black-Scholes option-pricing model with the following assumptions: 2015 2014 2013 Expected life (years) 4.0 4.0 4.0 Risk-free interest rate 1.1 % 1.2 % 0.6 % Volatility-historical 33.4 % 38.8 % 46.8 % Dividend yield 1.33 % 1.25 % 0.0 % Teradyne determined the stock option’s expected life based upon historical exercise data for executive officers, the age of executives and the terms of the stock option award. Volatility was determined using historical volatility for a period equal to the expected life. The interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Stock compensation plan activity for the years 2015, 2014 and 2013 follows: 2015 2014 2013 (in thousands) Restricted Stock Units: Non-vested at January 1 4,352 4,636 4,970 Awarded 1,681 1,870 2,110 Vested (1,679 ) (1,965 ) (2,322 ) Forfeited (284 ) (189 ) (122 ) Non-vested at December 31 4,070 4,352 4,636 Stock Options: Outstanding at January 1 1,507 2,706 3,841 Granted 132 89 213 Exercised (518 ) (1,248 ) (1,220 ) Forfeited — (38 ) (104 ) Expired — (2 ) (24 ) Outstanding at December 31 1,121 1,507 2,706 Vested and expected to vest at December 31 1,121 1,507 2,694 Exercisable at December 31 779 1,089 1,814 Total shares available for the years 2015, 2014 and 2013: 2015 2014 2013 (in thousands) Shares available: Available for grant at January 1 12,443 14,213 6,414 Options granted (132 ) (89 ) (213 ) Restricted stock units awarded (1,681 ) (1,870 ) (2,110 ) Restricted stock units forfeited 284 189 122 Additional shares reserved — — 10,000 Available for grant at December 31 10,914 12,443 14,213 Weighted average restricted stock unit award date fair value information for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Non-vested at January 1 $ 17.24 $ 15.60 $ 12.72 Awarded 17.36 18.41 16.62 Vested 16.85 14.38 10.40 Forfeited 17.08 16.97 15.48 Non-vested at December 31 $ 17.46 $ 17.24 $ 15.60 Restricted stock unit awards aggregate intrinsic value information at December 31 for the years 2015, 2014 and 2013 follows: 2015 2014 2013 (in thousands) Outstanding $ 84,129 $ 86,113 $ 81,680 Expected to vest 79,611 81,582 77,388 Restricted stock units weighted average remaining contractual terms (in years) information at December 31, for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Outstanding 1.09 1.11 1.14 Expected to vest 1.08 1.10 1.13 Weighted average stock options exercise price information for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Outstanding at January 1 $ 7.89 $ 6.29 $ 4.64 Options granted 18.10 19.16 16.56 Options exercised 5.49 5.34 3.28 Options forfeited 8.67 3.59 2.57 Options cancelled 3.28 2.21 8.05 Outstanding at December 31 10.21 7.89 6.29 Exercisable at December 31 6.92 5.00 4.55 Stock option aggregate intrinsic value information for the years ended December 31, 2015, 2014 and 2013 follows: 2015 2014 2013 (in thousands) Exercised $ 7,255 $ 17,847 $ 16,848 Outstanding 11,729 17,936 30,673 Vested and expected to vest 11,729 17,936 30,512 Exercisable 10,716 16,101 23,707 Stock options weighted average remaining contractual terms (in years) information at December 31, for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Outstanding 4.2 4.5 4.9 Vested and expected to vest 4.2 4.5 4.9 Exercisable 3.9 4.2 4.3 Significant option groups outstanding at December 31, 2015 and related weighted average price and remaining contractual life information follow: Options Outstanding Options Exercisable Range Of Exercise Prices Weighted- Shares Weighted- Shares Weighted- (shares in thousands) $1.48 – $2.67 4.58 416 $ 2.33 416 $ 2.33 $3.23 – $7.71 2.71 139 4.60 139 4.60 $11.37 – $16.95 3.54 345 16.63 202 16.62 $18.10 – $19.16 5.68 221 18.53 22 19.16 1,121 $ 10.21 779 $ 6.92 As of December 31, 2015, total unrecognized expense related to non-vested restricted stock unit awards and stock options was $44.9 million, and is expected to be recognized over a weighted average period of 2.3 years. Effective January 31, 2014, Michael Bradley retired as Chief Executive Officer of Teradyne. 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. Employee Stock Purchase Plan Under the Teradyne 1996 Employee Stock Purchase Plan (“ESPP”), eligible employees may purchase shares of common stock through regular payroll deductions of up to 10% of their compensation, to a maximum of shares with a fair market value of $25,000 per calendar year, not to exceed 6,000 shares. Under the plan, the price paid for the common stock is equal to 85% of the stock price on the last business day of the six month purchase period. In July 2015, 0.5 million shares of common stock were issued to employees who participated in the plan during the first half of 2015, at the price of $16.40 per share. In January 2016, Teradyne issued 0.5 million shares of common stock to employees who participated in the plan during the second half of 2015, at the price of $17.57 per share. In July 2014, 0.5 million shares of common stock were issued to employees who participated in the plan during the first half of 2014, at the price of $16.66 per share. In January 2015, Teradyne issued 0.5 million shares of common stock to employees who participated in the plan during the second half of 2014, at the price of $16.82 per share. In July 2013, 0.4 million shares of common stock were issued to employees who participated in the plan during the first half of 2013, at the price of $14.94 per share. In January 2014, Teradyne issued 0.4 million shares of common stock to employees who participated in the plan during the second half of 2013, at the price of $14.98 per share. As of December 31, 2015, there were 4.9 million shares available for grant under the ESPP. The effect to income from operations for recording stock-based compensation for the years ended December 31 was as follows: 2015 2014 2013 (in thousands) Cost of revenues $ 3,065 $ 3,675 $ 4,338 Engineering and development 9,362 10,146 12,452 Selling and administrative 18,024 26,486 19,822 Stock-based compensation 30,451 40,307 36,612 Income tax benefit (8,528 ) (11,537 ) (9,762 ) Total stock-based compensation expense after income taxes $ 21,923 $ 28,770 $ 26,850

Savings Plan

Savings Plan	12 Months Ended
	Dec. 31, 2015
Savings Plan	O. SAVINGS PLAN Teradyne sponsors a defined contribution employee retirement savings plan (“Savings Plan”) covering substantially all U.S. employees. Under the Savings Plan, employees may contribute up to 20% of their compensation (subject to Internal Revenue Service limitations). The Savings Plan provides for a discretionary employer match that is determined each year. In 2015, 2014 and 2013, Teradyne matched 100% of eligible employee contributions up to 4% of their compensation for employees not accruing benefits in the U.S. Qualified Pension Plan. There was no match for employees still actively accruing benefits in the U.S. Qualified Pension Plan. Teradyne’s contributions vest 25% per year for the first four years of employment, and contributions for those employees with four years of service vest immediately. In addition, Teradyne established an unfunded U.S. Supplemental Savings Plan to provide savings benefits in excess of those allowed by Employee Retirement Income Security Act of 1974 and the Internal Revenue Code. The provisions of this plan are the same as the Savings Plan. Teradyne also established defined contribution savings plans for its foreign employees. Under Teradyne’s savings plans, amounts charged to the statement of operations for the years ended December 31, 2015, 2014 and 2013 were $13.5 million, $12.8 million and $12.0 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Taxes	P. INCOME TAXES The components of income (loss) before income taxes and the provision for income taxes as shown in the consolidated statements of operations were as follows: 2015 2014 2013 (in thousands) Income (loss) before income taxes: U.S. $ 56,270 $ (151,889 ) $ 79,229 Non-U.S. 196,854 247,265 122,693 $ 253,124 $ 95,376 $ 201,922 Provision (benefit) for income taxes: Current: U.S. Federal $ 16,635 $ 5,197 $ 18,051 Non-U.S. 35,707 28,157 22,509 State 1,429 678 (269 ) 53,771 34,032 40,291 Deferred: U.S. Federal (574 ) (20,449 ) (1,692 ) Non-U.S. (7,761 ) (404 ) (1,386 ) State 1,211 925 (238 ) (7,124 ) (19,928 ) (3,316 ) Total provision for income taxes: $ 46,647 $ 14,104 $ 36,975 Income tax expense for 2015, 2014 and 2013 totaled $46.6 million, $14.1 million and $37.0 million, respectively. The effective tax rate for 2015, 2014 and 2013 was 18.4%, 14.8% and 18.3%, respectively. The increase in the effective tax rate from 2014 to 2015 resulted from a shift in the geographic distribution of income which increased income subject to taxation in the United States relative to lower tax rate jurisdictions and a reduction in the benefit from U.S. research and development tax credits. These increases in the effective tax rate were partially offset by decreases associated with uncertain tax positions and a non-deductible goodwill impairment charge. The decrease in the effective tax rate from 2013 to 2014 was primarily attributable to a shift in the geographic distribution of income which decreased income subject to taxation in the United States relative to lower tax rate jurisdictions, partially offset by increases in the effective tax rate associated with uncertain tax positions and a non-deductible goodwill impairment charge. A reconciliation of the effective tax rate for the years 2015, 2014 and 2013 follows: 2015 2014 2013 U.S. statutory federal tax rate 35.0 % 35.0 % 35.0 % Foreign taxes (16.5 ) (58.1 ) (11.4 ) Goodwill impairment — 36.3 — U.S. research and development credit (3.0 ) (7.9 ) (7.2 ) Uncertain tax positions 2.1 7.9 4.2 Valuation allowance — — 0.4 State income taxes, net of federal tax benefit 0.4 (0.1 ) 0.1 Other, net 0.4 1.7 (2.8 ) 18.4 % 14.8 % 18.3 % 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 attributable to the tax holiday for the years ended December 31, 2015, 2014 and 2013 were $11.5 million or $0.05 per diluted share, $13.2 million or $0.06 per diluted share and $4.7 million or $0.02 per diluted share, respectively. In December 2015, Teradyne entered into an agreement with the Singapore Economic Development Board which extended the tax holiday under substantially similar terms to the agreement which expired on December 31, 2015. The new tax holiday is scheduled to expire on December 31, 2020. Significant components of Teradyne’s deferred tax assets (liabilities) as of December 31, 2015 and 2014 were as follows: 2015 2014 (in thousands) Deferred tax assets: Tax credits $ 44,684 $ 50,554 Pension liabilities 31,742 30,036 Inventory valuations 29,445 29,105 Accruals 26,563 23,323 Deferred revenue 10,232 10,242 Equity compensation 9,674 11,131 Net operating loss carryforwards 7,989 10,989 Vacation accrual 7,354 7,425 Other 502 1,725 Gross deferred tax assets 168,185 174,530 Less: valuation allowance (43,039 ) (41,737 ) Total deferred tax assets $ 125,146 $ 132,793 Deferred tax liabilities: Intangible assets $ (68,433 ) $ (64,871 ) Depreciation (20,541 ) (24,905 ) Marketable securities (458 ) (1,599 ) Total deferred tax liabilities $ (89,432 ) $ (91,375 ) Net deferred assets $ 35,714 $ 41,418 Teradyne records all interest and penalties related to income taxes as a component of income tax expense. Accrued interest and penalties related to income tax items at December 31, 2015 and 2014 amounted to $0.5 million and $0.6 million respectively. For the years ended December 31, 2015, 2014 and 2013, benefit of $0.2 million, expense of $0.2 million and expense of $0.2 million respectively, was recorded for interest and penalties related to income tax items. During 2015, Teradyne’s valuation allowance increased by $1.3 million primarily due to the increase in the deferred tax assets related to state tax credits generated in 2015. As of December 31, 2015 and 2014, Teradyne evaluated the likelihood that it would realize the deferred income taxes to offset future taxable income and concluded that it is more likely than not that a substantial majority of its deferred tax assets will be realized through consideration of both the positive and negative evidence. At December 31, 2015 and 2014, Teradyne maintained a valuation allowance for certain deferred tax assets of $43.0 million and $41.7 million, respectively, primarily related to state net operating losses and state tax credit carryforwards, due to the uncertainty regarding their realization. Adjustments could be required in the future if Teradyne estimates that the amount of deferred tax assets to be realized is more or less than the net amount recorded. At December 31, 2015, Teradyne had operating loss carryforwards that expire in the following years: U.S. Federal State Foreign (in thousands) 2016 $ — $ 925 $ — 2017 — 10,649 — 2018 — 8,563 — 2019 — 1,203 — 2020 — 269 — 2021-2025 4,870 35,777 — 2026-2030 — 39,411 — Beyond 2030 — 6,359 143 Non-expiring — — 8,202 Total $ 4,870 $ 103,156 $ 8,345 Of the U.S. federal operating loss carryforwards, $4.9 million relates to the acquisition of GenRad, Inc. (“GenRad”) in 2001. GenRad losses are limited in the annual amount that can be used as a result of “change in ownership” rules as defined in the Internal Revenue Code of 1986. The operating loss carryforward does not include any excess tax deduction related to stock based compensation which has not been recognized for financial statement purposes. Teradyne has approximately $121.2 million of tax credit carryforwards. Federal business tax credits of approximately $43.2 million expire in the years 2017 through 2035. Teradyne has alternative minimum tax credits of approximately $6.6 million, which do not expire. In addition, there are state tax credits of $71.4 million of which $42.4 million do not expire and the remainder of which expires in the years 2016 through 2030. Teradyne has federal tax credits of $42.9 million, that are attributable to stock based compensation deductions which will be recorded as an increase in additional paid in capital on the consolidated balance sheet if and when they are “realized” in accordance with ASC 718-10, “Compensation—Stock Compensation.” Teradyne’s gross unrecognized tax benefits for the years ended December 31, 2015, 2014 and 2013 were as follows: 2015 2014 2013 (in thousands) Beginning balance, as of January 1 $ 30,418 $ 21,203 $ 18,666 Additions: Tax positions for current year 6,626 8,414 4,586 Tax positions for prior years 792 3,781 2,112 Reductions: Tax positions for prior years (708 ) (2,480 ) (4,161 ) Settlements with tax authorities (336 ) (500 ) — Ending balance as of December 31 $ 36,792 $ 30,418 $ 21,203 Current year and prior year additions include assessment of potential transfer pricing issues worldwide, federal and state tax credits and incentives, capitalization rules, and domestic production activities deductions. Reductions for tax positions for prior years primarily relate to statute expiration and the settlement of a foreign tax audit. Of the $36.8 million of unrecognized tax benefits as of December 31, 2015, $29.2 million would impact the consolidated income tax rate if ultimately recognized. The remaining $7.6 million would impact the valuation allowance if recognized. Teradyne estimates that it is reasonably possible that the balance of unrecognized tax benefits as of December 31, 2015 may decrease approximately $7.6 million in the next twelve months, as a result of a lapse of statutes of limitation and the settlement of a tax audit. The estimated decrease is composed primarily of reserves relating to federal tax credits and transfer pricing. Teradyne is subject to U.S. federal income tax, as well as income tax in multiple state, local and foreign jurisdictions. As of December 31, 2015, all material state and local income tax matters have been concluded through 2008, all material federal income tax matters have been concluded through 2011 and all material foreign income tax matters have been concluded through 2009. However, in some jurisdictions, including the United States, operating losses and tax credits may be subject to adjustment until such time as they are utilized and the year of utilization is closed to adjustment. As of December 31, 2015, a deferred tax liability has not been established for approximately $783 million of cumulative undistributed earnings of non-U.S. subsidiaries, which are expected to be reinvested indefinitely in operations outside the U.S. except for instances where Teradyne can remit such earnings to the U.S. without an associated net tax cost. Determination of the unrecognized deferred tax liability on unremitted earnings is not practicable due to uncertainty regarding the remittance structure, the mix of earnings and earnings and profit pools in the year of remittance, and overall complexity of the calculation.

Operating Segment, Geographic a

Operating Segment, Geographic and Significant Customer Information	12 Months Ended
	Dec. 31, 2015
Operating Segment, Geographic and Significant Customer Information	Q. OPERATING SEGMENT, GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION Teradyne has four operating segments (Semiconductor Test, System Test, Wireless Test and Industrial Automation), 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 System Test segment includes operations related to the design, manufacturing and marketing of products and services for defense/aerospace instrumentation test, storage test and circuit-board test. The Wireless Test segment includes operations related to the design, manufacturing and marketing of wireless test products and services. The Industrial Automation segment includes operations related to the design, manufacturing and marketing of collaborative robots. 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 using several factors, of which the primary financial measure is business segment income (loss) from operations before taxes. The accounting policies of the business segments are the same as those described in Note B: “Accounting Policies.” Segment information for the years ended December 31, 2015, 2014 and 2013 is as follows: Semiconductor Wireless Test System Industrial Corporate Consolidated (in thousands) 2015 Revenues $ 1,201,530 $ 184,572 $ 211,584 $ 41,892 $ — $ 1,639,578 Income (loss) before taxes (1)(2) 260,154 (13,830 ) 25,101 (7,574 ) (10,727 ) 253,124 Total assets (3) 610,869 427,880 102,547 344,260 1,063,118 2,548,674 Property additions 79,052 3,133 6,228 1,465 — 89,878 Depreciation and amortization expense 64,415 53,440 4,390 14,500 4,027 140,772 2014 Revenues $ 1,300,790 $ 184,535 $ 162,499 $ — $ — $ 1,647,824 Income (loss) before taxes (1)(2) 255,803 (116,196 ) 12,116 — (56,347 ) 95,376 Total assets (3) 580,501 478,974 95,105 — 1,383,940 2,538,520 Property additions 159,783 3,730 5,469 — — 168,982 Depreciation and amortization expense 84,990 53,308 5,399 — 8,847 152,544 2013 Revenues $ 1,023,041 $ 251,871 $ 153,021 $ — $ — $ 1,427,933 Income before taxes (1)(2) 153,797 23,153 3,115 — 21,857 201,922 Total assets (3) 632,840 645,001 79,983 — 1,272,000 2,629,824 Property additions 94,303 5,358 7,070 — — 106,731 Depreciation and amortization expense 72,472 51,675 5,180 — 21,360 150,687 (1) Interest income, interest expense, other (income) expense, net, contingent consideration adjustments and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges and goodwill impairment charges. (3) Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets. Included in the Semiconductor Test segment are charges in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory charge $ 10,508 $ 14,389 $ 5,218 Restructuring and other 499 490 1,016 Included in the System Test segment are charges in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory charge $ 8,324 $ 2,125 $ 4,168 Restructuring and other 1,037 742 1,431 Included in the Wireless Test segment are charges in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory charge $ 2,500 $ 5,679 $ 7,206 Restructuring and other — 565 82 Goodwill impairment charge — 98,897 — Included in the Industrial Automation segment are charges in the following account: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory step-up (1) $ 1,567 $ — $ — (1) Included in the cost of revenues for the years ended December 31, 2015 is the cost for purchase accounting inventory step-up. Included in the Corporate and Eliminations segment are charges and credits in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Restructuring and other—Universal Robots contingent consideration adjustment $ 5,339 $ — $ — Restructuring and other—ZTEC contingent consideration adjustment (1,600 ) (630 ) — Restructuring and other—AIT contingent consideration adjustment (1,250 ) — — Restructuring and other—acquisition costs 1,104 372 — Restructuring and other — 198 (449 ) Other (income) expense, net—gain from the sale of an equity investment (5,406 ) — (34,212 ) Selling and administrative—stock based compensation expense (1) — 6,598 — (1) Expense related to the January 2014 retirement of Teradyne’s former chief executive officer; see Note N: “Stock-Based Compensation.” Information as to Teradyne’s revenues by country is as follows: 2015 2014 2013 (in thousands) Revenues from customers (1): Taiwan $ 436,389 $ 495,942 $ 265,472 China 264,898 292,145 323,564 United States 217,386 213,104 230,178 Japan 128,228 63,761 81,806 Korea 120,224 145,608 119,286 Europe 111,903 111,043 90,797 Singapore 105,216 119,421 114,765 Philippines 96,103 68,662 63,392 Malaysia 76,707 83,910 86,900 Thailand 59,104 44,117 32,209 Rest of the World 23,420 10,111 19,564 $ 1,639,578 $ 1,647,824 $ 1,427,933 (1) Revenues attributable to a country are based on location of customer site. In 2015, one customer of Teradyne’s Semiconductor Test segment accounted for 13% of total consolidated revenues. In 2014, no single customer accounted for more than 10% of total consolidated revenues. In 2013, one customer of Teradyne’s Wireless Test and Semiconductor Test segments, accounted for 12% of total consolidated revenues. Long-lived assets by geographic area: United Foreign(1) Total (in thousands) December 31, 2015 $ 198,424 $ 74,990 $ 273,414 December 31, 2014 $ 206,334 $ 122,704 $ 329,038 (1) As of December 31, 2015 and 2014, long-lived assets attributable to Singapore were $39.9 million and $99.2 million, respectively.

Stock Repurchase Program

Stock Repurchase Program	12 Months Ended
	Dec. 31, 2015
Stock Repurchase Program	R. STOCK REPURCHASE PROGRAM In January 2015, the Board of Directors cancelled the November 2010 stock repurchase program and authorized a new stock repurchase program for up to $500 million of common stock. The cumulative repurchases as of December 31, 2015 totaled 15.6 million shares of common stock for a total purchase price of $300 million at an average price per share of $19.20. The total price includes commissions and is recorded as a reduction to retained earnings. In November 2010, the Board authorized a stock repurchase program for up to $200 million. Under the November 2010 plan, Teradyne repurchased 2.6 million shares of common stock for $31.2 million at an average price of $11.84.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events	S. SUBSEQUENT EVENTS In January 2016, Teradyne’s Board of Directors declared a quarterly dividend of $0.06 per share to be paid on March 21, 2016 to shareholders of record as of February 26, 2016. While Teradyne declared a quarterly cash dividend and authorized a share repurchase program, it may reduce or eliminate the cash dividend or share repurchase program in the future. Future cash dividends and stock repurchases are subject to the discretion of Teradyne’s Board of Directors which will consider, among other things, Teradyne’s earnings, capital requirements and financial condition.

Supplementary Information

Supplementary Information	12 Months Ended
	Dec. 31, 2015
Supplementary Information	SUPPLEMENTARY INFORMATION (Unaudited) The following sets forth certain unaudited consolidated quarterly statements of operations data for each of Teradyne’s last eight quarters. In management’s opinion, this quarterly information reflects all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement for the periods presented. Such quarterly results are not necessarily indicative of future results of operations and should be read in conjunction with the audited consolidated financial statements of Teradyne and the notes thereto included elsewhere herein. 2015 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (3) (4) (1)(2) (in thousands, except per share amounts) Revenues: Products $ 272,325 $ 437,243 $ 386,488 $ 244,510 Services 70,076 75,496 79,506 73,934 Total revenues 342,401 512,739 465,994 318,444 Cost of revenues: Cost of products 118,996 181,491 170,963 120,322 Cost of services 30,982 32,680 36,405 32,096 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 149,978 214,171 207,368 152,418 Gross profit 192,423 298,568 258,626 166,026 Operating expenses: Engineering and development 71,450 75,832 74,027 70,941 Selling and administrative 72,041 77,073 77,481 79,718 Acquired intangible assets amortization 13,808 15,258 20,053 19,911 Restructuring and other — (385 ) 261 5,204 Total operating expenses 157,299 167,778 171,822 175,774 Income (loss) from operations 35,124 130,790 86,804 (9,748 ) Non-operating (income) expense: Interest income (1,816 ) (1,674 ) (1,708 ) (2,017 ) Interest expense 162 444 508 762 Other (income) expense, net (5,660 ) (116 ) 596 364 Income (loss) before income taxes 42,438 132,136 87,408 (8,857 ) Income tax provision (benefit) 9,651 29,257 15,955 (8,216 ) Net income (loss) $ 32,787 $ 102,879 $ 71,453 $ (641 ) Net income (loss) per common share—basic $ 0.15 $ 0.48 $ 0.34 $ (0.00 ) Net income (loss) per common share—diluted $ 0.15 $ 0.48 $ 0.34 $ (0.00 ) Cash dividend declared per common share $ 0.06 $ 0.06 $ 0.06 $ 0.06 (1) Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration. (2) In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: “Accounting Policies” for a discussion of our accounting policy. (3) Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration. (4) Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration. 2014 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (1)(2) (1)(3)(4) (in thousands, except per share amounts) Revenues: Products $ 255,386 $ 452,488 $ 402,987 $ 253,162 Services 65,624 73,079 75,023 70,074 Total revenues 321,010 525,567 478,010 323,236 Cost of revenues: Cost of products 124,448 202,411 182,591 131,337 Cost of services 29,515 32,743 34,298 31,673 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 153,963 235,154 216,889 163,010 Gross profit 167,047 290,413 261,121 160,226 Operating expenses: Engineering and development 67,085 73,414 71,953 79,188 Selling and administrative 78,003 77,489 73,064 91,157 Goodwill impairment — — — 98,897 Acquired intangible assets amortization 18,271 18,271 18,271 15,957 Restructuring and other — 572 (405 ) 1,198 Total operating expenses 163,359 169,746 162,883 286,397 Income (loss) from operations 3,688 120,667 98,238 (126,171 ) Non-operating (income) expense: Interest income (1,036 ) (1,266 ) (1,922 ) (2,035 ) Interest expense 6,417 159 144 214 Other (income) expense, net 180 382 (654 ) 463 (Loss) income before income taxes (1,873 ) 121,392 100,670 (124,813 ) Income tax (benefit) provision (2,802 ) 20,187 17,721 (21,002 ) Net income (loss) $ 929 $ 101,205 $ 82,949 $ (103,811 ) Net income (loss) per common share—basic $ 0.00 $ 0.52 $ 0.40 $ (0.48 ) Net income (loss) per common share—diluted $ 0.00 $ 0.47 $ 0.38 $ (0.48 ) Cash dividend declared per common share $ 0.00 $ 0.06 $ 0.06 $ 0.06 (1) Dividends declared by Teradyne’s Board of Directors were paid in the second, third and fourth quarters of 2014. (2) Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration. (3) In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: “Accounting Policies” for a discussion of our accounting policy. (4) In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts	TERADYNE, INC. SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS Column A Column B Column C Column D Column E Column F Description Balance at Additions Other Deductions Balance at (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Accounts receivable: 2015 Allowance for doubtful accounts $ 2,491 $ — $ — $ 84 $ 2,407 2014 Allowance for doubtful accounts $ 2,912 $ 55 $ — $ 476 $ 2,491 2013 Allowance for doubtful accounts $ 4,118 $ 69 $ — $ 1,275 (1) $ 2,912 (1) Based upon an improvement in the aging of accounts receivables in 2013, Teradyne reduced its allowance for doubtful accounts by approximately $1 million. Column A Column B Column C Column D Column E Column F Description Balance at Additions Other Deductions Balance at (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Inventory: 2015 Inventory reserve $ 111,252 $ 21,332 $ 1,680 $ 14,888 $ 119,376 2014 Inventory reserve $ 115,857 $ 22,193 $ 7,064 $ 33,862 $ 111,252 2013 Inventory reserve $ 141,838 $ 16,592 $ 2,568 $ 45,141 $ 115,857 Column A Column B Column C Column D Column E Column F Description Balance at Additions Other Deductions Balance at (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Deferred taxes: 2015 Valuation allowance $ 41,737 $ 1,322 $ — $ 20 $ 43,039 2014 Valuation allowance $ 40,386 $ 1,380 $ — $ 29 $ 41,737 2013 Valuation allowance $ 55,446 $ 4,546 $ — $ 19,606 $ 40,386

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
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 reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going basis, management evaluates its estimates, including those related to inventories, investments, goodwill, intangible and other long-lived assets, accounts receivable, income taxes, deferred tax assets, pensions, warranties, and loss contingencies. Management bases its estimates on historical experience and on appropriate and customary assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ significantly from these estimates.
Revenue Recognition	Revenue Recognition Teradyne recognizes revenue when there is persuasive evidence of an arrangement, title and risk of loss have passed, delivery has occurred or the services have been rendered, the sales price is fixed or determinable and collection of the related receivable is reasonably assured. Title and risk of loss generally pass to Teradyne’s customers upon shipment or at delivery destination point. In circumstances where either title or risk of loss pass upon destination, acceptance or cash payment, Teradyne defers revenue recognition until such events occur except when title transfer is tied to cash payment outside the United States. Outside the United States, Teradyne recognizes revenue upon shipment or at delivery destination point, even if Teradyne retains a form of title to products delivered to customers, provided the sole purpose is to enable Teradyne to recover the products in the event of customer payment default and the arrangement does not prohibit the customer’s use or resale of the product in the ordinary course of business. Teradyne’s equipment has non-software and software components that function together to deliver the equipment’s essential functionality. Revenue is recognized upon shipment or at delivery destination point, provided that customer acceptance criteria can be demonstrated prior to shipment. Certain contracts require Teradyne to perform tests of the product to ensure that performance meets the published product specifications or customer requested specifications, which are generally conducted prior to shipment. Where the criteria cannot be demonstrated prior to shipment, revenue is deferred until customer acceptance has been received. Teradyne also defers the portion of the sales price that is not due until acceptance, which represents deferred profit. For multiple element arrangements, Teradyne allocates revenue to all deliverables based on their relative selling prices. In such circumstances, a hierarchy is used to determine the selling price for allocating revenue to deliverables as follows: (i) vendor-specific objective evidence of selling price (“VSOE”), (ii) third-party evidence of selling price (“TPE”), and (iii) best estimate of the selling price (“BESP”). For a delivered item to be considered a separate unit the delivered item must have value to the customer on a standalone basis and the delivery or performance of the undelivered item must be considered probable and substantially in Teradyne’s control. Teradyne’s post-shipment obligations include installation, training services, one-year standard warranties, and extended warranties. Installation does not alter the product capabilities, does not require specialized skills or tools and can be performed by the customers or other vendors. Installation is typically provided within five days of product shipment and is completed within one to two days thereafter. Training services are optional and do not affect the customers’ ability to use the product. Teradyne defers revenue for the selling price of installation and training. Extended warranties constitute warranty obligations beyond one year and Teradyne defers revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605-20, “Separately Priced Extended Warranty and Product Maintenance Contracts” “Revenue Recognition Multiple-Element Arrangements.” Teradyne’s products are generally subject to warranty and related costs of the warranty are provided for in cost of revenues when product revenue is recognized. Teradyne classifies shipping and handling costs in cost of revenue. Teradyne does not provide its customers with contractual rights of return for any of its products. As of December 31, 2015 and 2014, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2015 2014 (in thousands) Extended warranty $ 46,499 $ 43,300 Equipment maintenance and training 30,616 30,500 Customer advances 17,456 8,875 Undelivered elements and other 16,701 8,857 Total deferred revenue and customer advances $ 111,272 $ 91,532
Product Warranty	Product Warranty Teradyne generally provides a one-year warranty on its products, commencing upon installation, acceptance 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 balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2012 $ 9,786 Accruals for warranties issued during the period 10,574 Accruals related to pre-existing warranties (3,534 ) Settlements made during the period (10,166 ) Balance at December 31, 2013 6,660 Accruals for warranties issued during the period 15,406 Accruals related to pre-existing warranties (2,008 ) Settlements made during the period (11,116 ) Balance at December 31, 2014 8,942 Acquisition 409 Accruals for warranties issued during the period 11,539 Accruals related to pre-existing warranties (3,159 ) Settlements made during the period (10,806 ) Balance at December 31, 2015 $ 6,925 When Teradyne receives revenue for extended warranties, beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2012 $ 28,044 Deferral of new extended warranty revenue 20,630 Recognition of extended warranty deferred revenue (13,765 ) Balance at December 31, 2013 34,909 Deferral of new extended warranty revenue 29,519 Recognition of extended warranty deferred revenue (21,128 ) Balance at December 31, 2014 43,300 Acquisition 870 Deferral of new extended warranty revenue 28,549 Recognition of extended warranty deferred revenue (26,220 ) Balance at December 31, 2015 $ 46,499
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The volatility of the industries that Teradyne serves can cause certain of its customers to experience shortages of cash flows, which can impact their ability to make required payments. Teradyne maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Estimated allowances for doubtful accounts are reviewed periodically taking into account the customer’s recent payment history, the customer’s current financial statements and other information regarding the customer’s credit worthiness. Account balances are written off against the allowance when it is determined the receivable will not be recovered.
Inventories	Inventories Inventories are stated at the lower of cost (first-in, first-out basis) or net realizable value. On a quarterly basis, Teradyne uses consistent methodologies to evaluate all inventories for net realizable value. Teradyne records a provision for both excess and obsolete inventory when such write-downs or write-offs are identified through the quarterly review process. The inventory valuation is based upon assumptions about future demand, product mix and possible alternative uses.
Investments	Investments Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, “ Investments—Debt and Equity Securities. • 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. As defined in ASC 820-10, “ Fair Value Measurements and Disclosures, 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. Matrix pricing is a mathematical technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, and therefore is considered a Level 2 input. 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. In accordance with ASC 820-10, Teradyne measures its debt and equity investments at fair value. Teradyne’s debt and equity investments are primarily classified within Level 1 and 2. Acquisition-related contingent consideration is classified within Level 3. Teradyne determines the fair value of acquisition-related contingent consideration based on an assessment of the probability that it would be required to make such payment.
Prepayments	Prepayments Prepayments consist of the following and are included in prepayments on the balance sheet: 2015 2014 (in thousands) Contract manufacturer prepayments $ 66,283 $ 65,972 Prepaid maintenance and other services 8,481 7,343 Prepaid taxes 3,781 11,462 Other prepayments 12,974 11,042 Total prepayments $ 91,519 $ 95,819
Retirement and Postretirement Plans	Retirement and Postretirement Plans Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans.
Goodwill, Intangible and Long-Lived Assets	Goodwill, Intangible and Long-Lived Assets Teradyne accounts for goodwill and intangible assets in accordance with ASC 350-10, “Intangibles-Goodwill and Other.” In accordance with ASC 360-10 , “Impairment or Disposal of Long-Lived Assets,”
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost and depreciated over the estimated useful lives of the assets. Leasehold improvements and major renewals are capitalized and included in property, plant and equipment accounts while expenditures for maintenance and repairs and minor renewals are charged to expense. When assets are retired, the assets and related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the statement of operations. Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 years Building improvements 5 to 10 years Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 years Machinery and equipment 3 to 5 years Software 3 to 5 years Test systems manufactured internally are used by Teradyne for customer evaluations and manufacturing and support of its customers. Teradyne depreciates the test systems manufactured internally over a six-year life to cost of revenues, engineering and development, and selling and administrative expenses. Teradyne often sells internally manufactured test equipment to customers. Upon the sale of an internally manufactured test system, the net book value of the system is transferred to inventory and expensed as cost of revenues. The net book value of internally manufactured test systems sold in the years ended December 31, 2015, 2014 and 2013 was $50.7 million, $9.7 million and $9.0 million, respectively.
Engineering and Development Costs	Engineering and Development Costs Teradyne’s products are highly technical in nature and require a large and continuing engineering and development effort. Software development costs incurred prior to the establishment of technological feasibility are charged to expense. Software development costs incurred subsequent to the establishment of technological feasibility are capitalized until the product is available for release to customers. To date, the period between achieving technological feasibility and general availability of the product has been short and software development costs eligible for capitalization have not been material. Engineering and development costs are expensed as incurred and consist primarily of salaries, contractor fees, allocated facility costs, depreciation, and tooling costs.
Stock Compensation Plans and Employee Stock Purchase Plan	Stock Compensation Plans and Employee Stock Purchase Plan Stock-based compensation expense is based on the grant-date fair value estimated in accordance with the provisions of ASC 718-10, “ Compensation-Stock Compensation Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”).
Income Taxes	Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The measurement of deferred tax assets is reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be realized. Teradyne performed the required assessment of positive and negative evidence regarding the realization of the net deferred tax assets in accordance with ASC 740, “Accounting for Income Taxes.” This assessment included the evaluation of scheduled reversals of deferred tax liabilities, estimates of projected future taxable income and tax-planning strategies. Although realization is not assured, based on its assessment, Teradyne concluded that it is more likely than not that such assets, net of the existing valuation allowance, will be realized. U.S. income taxes are not provided for on the earnings of non-U.S. subsidiaries which are expected to be reinvested indefinitely in operations outside the U.S. For intra-period tax allocations, Teradyne first utilizes non-equity related tax attributes, such as net operating losses and credit carryforwards and then equity-related tax attributes. Teradyne uses the with-and-without method for calculating excess stock compensation deductions and does not take into account any indirect impacts of excess stock compensation deductions on its research and development tax credits, domestic production activities deduction, and other differences between financial reporting and tax reporting.
Advertising Costs	Advertising Costs Teradyne expenses all advertising costs as incurred. Advertising costs were $3.3 million, $1.9 million and $1.7 million in 2015, 2014 and 2013, respectively.
Translation of Non-U.S. Currencies	Translation of Non-U.S. Currencies The functional currency for all subsidiaries is the U.S. dollar, except for the Industrial Automation segment for which the local currency is its functional currency. All foreign currency denominated monetary assets and liabilities are remeasured on a monthly basis into the functional currency using exchange rates in effect at the end of the period. All foreign currency denominated non-monetary assets and liabilities are remeasured into the functional currency using historical exchange rates. Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For Industrial Automation, assets and liabilities are translated into U.S. dollars using exchange rates in effect at the end of the period. Revenue and expense amounts are translated using an average of exchange rates in effect during the period. Translation adjustments are recorded within accumulated other comprehensive income (loss). Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net and were a gain of $2.5 million, a loss of $0.9 million and a loss of $6.9 million, respectively, for the years ended December 31, 2015, 2014 and 2013. These amounts do not reflect the corresponding gains (losses) from foreign exchange contracts. See Note F: “Financial Instruments” regarding foreign exchange contracts.
Net Income per Common Share	Net Income per Common Share Basic net income per common share is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Except where the result would be antidilutive, diluted net income per common share is calculated by dividing net income by the sum of the weighted average number of common shares plus common stock equivalents, if applicable. Dilutive potential common shares included incremental shares from the assumed conversion of the convertible notes and the convertible notes hedge warrant shares, during the periods the convertible notes and warrants were outstanding. Incremental shares from the assumed conversion of the convertible notes were calculated using the difference between the average Teradyne stock price for the period and the conversion price of $5.48, 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. Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.67, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne’s call option for 34.7 million shares at an exercise price of $5.48 was not used in the GAAP earnings per share calculation as its effect was anti-dilutive. Teradyne settled its conversion spread (i.e., the intrinsic value of the embedded option feature contained in the convertible debt) in shares. Teradyne accounted for its conversion spread using the treasury stock method. Teradyne determined that it had the ability and intent to settle the principal amount of the convertible debt in cash; accordingly, the principal amount was excluded from the determination of diluted earnings per share.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) includes net income, unrealized pension and postretirement prior service costs and benefits, unrealized gains and losses on investments in debt and equity marketable securities and foreign currency translation adjustment.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Deferred Revenue and Customer Advances	As of December 31, 2015 and 2014, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2015 2014 (in thousands) Extended warranty $ 46,499 $ 43,300 Equipment maintenance and training 30,616 30,500 Customer advances 17,456 8,875 Undelivered elements and other 16,701 8,857 Total deferred revenue and customer advances $ 111,272 $ 91,532
Warranty Accrual Included in Other Accrued Liabilities	The balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2012 $ 9,786 Accruals for warranties issued during the period 10,574 Accruals related to pre-existing warranties (3,534 ) Settlements made during the period (10,166 ) Balance at December 31, 2013 6,660 Accruals for warranties issued during the period 15,406 Accruals related to pre-existing warranties (2,008 ) Settlements made during the period (11,116 ) Balance at December 31, 2014 8,942 Acquisition 409 Accruals for warranties issued during the period 11,539 Accruals related to pre-existing warranties (3,159 ) Settlements made during the period (10,806 ) Balance at December 31, 2015 $ 6,925
Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances	The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2012 $ 28,044 Deferral of new extended warranty revenue 20,630 Recognition of extended warranty deferred revenue (13,765 ) Balance at December 31, 2013 34,909 Deferral of new extended warranty revenue 29,519 Recognition of extended warranty deferred revenue (21,128 ) Balance at December 31, 2014 43,300 Acquisition 870 Deferral of new extended warranty revenue 28,549 Recognition of extended warranty deferred revenue (26,220 ) Balance at December 31, 2015 $ 46,499
Schedule of Prepayments	Prepayments consist of the following and are included in prepayments on the balance sheet: 2015 2014 (in thousands) Contract manufacturer prepayments $ 66,283 $ 65,972 Prepaid maintenance and other services 8,481 7,343 Prepaid taxes 3,781 11,462 Other prepayments 12,974 11,042 Total prepayments $ 91,519 $ 95,819
Useful Lives of Assets	Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 years Building improvements 5 to 10 years Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 years Machinery and equipment 3 to 5 years Software 3 to 5 years

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2015
Universal Robots
Final Allocation of Purchase Price	The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 221,128 Intangible assets 121,590 Tangible assets acquired and liabilities assumed: Current assets 10,853 Non-current assets 3,415 Accounts payable and current liabilities (11,976 ) Long-term deferred tax liabilities (26,653 ) Long-term other liabilities (2,920 ) Total purchase price $ 315,437
Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date	Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 89,240 4.9 Trademarks and tradenames 22,920 10.0 Customer relationships 9,430 2.0 Total intangible assets $ 121,590 5.6
Pro Forma Results Under Acquisitions	The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Years Ended December 31, December 31, (in thousands, except per Revenue $ 1,657,626 $ 1,686,689 Net income 199,784 61,078 Net income per common share: Basic $ 0.94 $ 0.30 Diluted $ 0.94 $ 0.27
Avionics Interface Technologies, LLC
Final Allocation of Purchase Price	The following represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 10,516 Intangible assets 9,080 Tangible assets acquired and liabilities assumed: Current assets 2,452 Non-current assets 359 Accounts payable and current liabilities (1,164 ) Total purchase price $ 21,243
Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date	Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Customer relationships $ 5,630 5.0 Developed technology 2,580 4.8 Trademarks and tradenames 380 5.0 Non-compete agreement 320 4.0 Customer order backlog 170 0.3 Total intangible assets $ 9,080 4.8
Pro Forma Results Under Acquisitions	The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Year Ended December 31, December 31, (in thousands, except per Revenues $ 1,655,038 $ 1,434,699 Net income $ 82,169 $ 164,087 Income per common share: Basic $ 0.40 $ 0.86 Diluted $ 0.37 $ 0.70
ZTEC Instruments, Inc.
Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date	Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 3,500 5.0 Customer relationships 1,370 6.0 Total intangible assets $ 4,870 5.3
Pro Forma Results Under Acquisitions	The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Year Ended December 31, (in thousands, except Revenues $ 1,431,270 Net income $ 163,394 Income per common share: Basic $ 0.86 Diluted $ 0.69
Final Allocation of Purchase Price	The following represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 12,520 Intangible assets 4,870 Tangible assets acquired and liabilities assumed: Cash 79 Other current assets 1,612 Non-current assets 1,757 Accounts payable and current liabilities (1,811 ) Long-term deferred tax liabilities (1,719 ) Total purchase price $ 17,308

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property Plant and Equipment	Property, plant and equipment consist of the following: 2015 2014 (in thousands) Land $ 16,561 $ 16,561 Buildings 108,797 108,671 Machinery and equipment 595,445 659,743 Furniture and fixtures, and software 82,612 77,566 Leasehold improvements 43,328 31,981 Construction in progress 2,630 2,508 849,373 897,030 Less: accumulated depreciation 575,959 567,992 $ 273,414 $ 329,038

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
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 December 31, 2015 and 2014: December 31, 2015 Quoted Prices Significant Significant Total (in thousands) Assets Cash $ 213,336 $ — $ — $ 213,336 Cash equivalents 49,241 2,128 — 51,369 Available for sale securities: U.S. Treasury securities — 419,958 — 419,958 Corporate debt securities — 161,634 — 161,634 U.S. government agency securities — 83,952 — 83,952 Certificates of deposit and time deposits — 43,394 — 43,394 Commercial paper — 20,308 — 20,308 Equity and debt mutual funds 13,954 — — 13,954 Non-U.S. government securities — 424 — 424 Total $ 276,531 $ 731,798 $ — $ 1,008,329 Derivative assets — 109 — 109 Total $ 276,531 $ 731,907 $ — $ 1,008,438 Liabilities Contingent consideration $ — $ — $ 37,436 $ 37,436 Derivative liabilities — 146 — 146 Total $ — $ 146 $ 37,436 $ 37,582 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 262,577 $ 2,128 $ — $ 264,705 Marketable securities — 477,696 — 477,696 Long-term marketable securities 13,954 251,974 — 265,928 Prepayments — 109 — 109 $ 276,531 $ 731,907 $ — $ 1,008,438 Liabilities Other current liabilities $ — $ 146 $ — $ 146 Contingent consideration — — 15,500 15,500 Long-term contingent consideration — — 21,936 21,936 $ — $ 146 $ 37,436 $ 37,582 December 31, 2014 Quoted Prices Significant Significant Total (in thousands) Assets Cash $ 111,471 $ — $ — $ 111,471 Cash equivalents 160,218 22,567 — 182,785 Available for sale securities: U.S. Treasury securities — 402,154 — 402,154 U.S. government agency securities — 258,502 — 258,502 Corporate debt securities — 141,467 — 141,467 Commercial paper — 140,638 — 140,638 Certificates of deposit and time deposits — 49,036 — 49,036 Equity and debt mutual funds 12,333 — — 12,333 Non-U.S. government securities — 446 — 446 Total $ 284,022 $ 1,014,810 $ — $ 1,298,832 Derivative assets — 220 — 220 Total $ 284,022 $ 1,015,030 $ — $ 1,299,052 Liabilities Contingent consideration $ — $ — $ 3,350 $ 3,350 Derivative liabilities — 369 — 369 Total $ — $ 369 $ 3,350 $ 3,719 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 271,689 $ 22,567 $ — $ 294,256 Marketable securities — 533,787 — 533,787 Long-term marketable securities 12,333 458,456 — 470,789 Prepayments — 220 — 220 $ 284,022 $ 1,015,030 $ — $ 1,299,052 Liabilities Other current liabilities $ — $ 369 $ — $ 369 Contingent consideration — — 895 895 Long-term other accrued liabilities — — 2,455 2,455 $ — $ 369 $ 3,350 $ 3,719
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	Changes in the fair value of Level 3 contingent consideration for the years ended December 31, 2015 and 2014 were as follows: Contingent Consideration (in thousands) Balance at December 31, 2013 $ 2,230 Acquisition of AIT 1,750 Fair value adjustment of ZTEC (630 ) Balance at December 31, 2014 3,350 Acquisition of Universal Robots 31,597 Fair value adjustment of ZTEC (1,600 ) Fair value adjustment of AIT (1,250 ) Fair value adjustment of Universal Robots 5,339 Balance at December 31, 2015 $ 37,436
Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument	The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instrument: Liability December 31, Valuation Unobservable Inputs Weighted (in thousands) Contingent consideration (Universal Robots) $ 21,936 Monte Carlo Revenue for the period July 1, 2015—December 31, 2017 volatility 15% Discount Rate 5.5% Revenue for the period July 1, 2015—December 31, 2018 volatility 15% Discount Rate 5.5% Contingent consideration (AIT) $ 500 Income approach- Revenue for calendar year 2016 probability 48% Discount rate 4.7%
Schedule of Carrying Amounts and Fair Values of Financial Instruments	The carrying amounts and fair values of financial instruments at December 31, 2015 and 2014 were as follows: December 31, 2015 December 31, 2014 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 264,705 $ 264,705 $ 294,256 $ 294,256 Marketable securities 743,624 743,624 1,004,576 1,004,576 Derivative assets 109 109 220 220 Liabilities Contingent consideration 37,436 37,436 3,350 3,350 Derivative liabilities 146 146 369 369
Schedule of Available-for-Sale Marketable Securities	The following tables summarize the composition of available for sale marketable securities at December 31, 2015 and 2014: December 31, 2015 Available-for-Sale Fair Market Cost Unrealized Unrealized Fair Market (in thousands) U.S. Treasury securities $ 421,060 $ 65 $ (1,167 ) $ 419,958 $ 379,434 Corporate debt securities 163,297 902 (2,565 ) 161,634 145,373 U.S. government agency securities 84,032 42 (122 ) 83,952 55,120 Certificates of deposit and time deposits 43,391 6 (3 ) 43,394 10,527 Commercial paper 20,298 11 (1 ) 20,308 8,646 Equity and debt mutual funds 12,996 1,119 (161 ) 13,954 2,560 Non-U.S. government securities 424 — — 424 — $ 745,498 $ 2,145 $ (4,019 ) $ 743,624 $ 601,660 Reported as follows: Cost Unrealized Unrealized Fair Market Fair Market (in thousands) Marketable securities $ 478,306 $ 38 $ (648 ) $ 477,696 $ 374,785 Long-term marketable securities 267,192 2,107 (3,371 ) 265,928 226,875 $ 745,498 $ 2,145 $ (4,019 ) $ 743,624 $ 601,660 December 31, 2014 Available-for-Sale Fair Market Cost Unrealized Unrealized Fair Market (in thousands) U.S. Treasury securities $ 402,197 $ 362 $ (405 ) $ 402,154 $ 317,771 U.S. government agency securities 258,452 135 (85 ) 258,502 104,642 Corporate debt securities 139,374 2,414 (321 ) 141,467 96,998 Commercial paper 140,616 26 (4 ) 140,638 41,747 Certificates of deposit and time deposits 49,048 11 (23 ) 49,036 20,684 Equity and debt mutual funds 10,492 1,870 (29 ) 12,333 1,234 Non-U.S. government securities 446 — — 446 — $ 1,000,625 $ 4,818 $ (867 ) $ 1,004,576 $ 583,076 Reported as follows: Cost Unrealized Unrealized Fair Market Fair Market (in thousands) Marketable securities $ 533,833 $ 99 $ (145 ) $ 533,787 $ 240,234 Long-term marketable securities 466,792 4,719 (722 ) 470,789 342,842 $ 1,000,625 $ 4,818 $ (867 ) $ 1,004,576 $ 583,076
Contractual Maturities of Investments Held	The contractual maturities of investments held at December 31, 2015 were as follows: Cost Fair Value (in thousands) Due within one year $ 478,306 $ 477,696 Due after 1 year through 5 years 209,822 209,314 Due after 5 years through 10 years 5,183 5,179 Due after 10 years 39,191 37,481 Total $ 732,502 $ 729,670
Assets Measured at Fair Value on Non-Recurring Basis	Assets measured at fair value on a non-recurring basis as of December 31, 2014 are summarized as follows: Fair Value Measurements at Reporting Period December 31, Quoted Prices Significant Significant Total Losses (in thousands) Assets Goodwill $ 273,438 $ — $ — $ 273,438 $ 98,897 Definite lived intangible assets 158,237 — — 158,237 — Long-lived assets held and used 10,189 — 10,189 — — $ 441,864 $ — $ 10,189 $ 431,675 $ 98,897
Schedule of Notional Amount of Derivatives	At December 31, 2015 and 2014, Teradyne had the following contracts to buy and sell non-U.S. currencies for U.S. dollars and other non-U.S. currencies with the following notional amounts: December 31, 2015 December 31, 2014 Buy Sell Net Buy Sell Net (in millions) Japanese Yen $ (51.9 ) $ — $ (51.9 ) $ — $ 19.7 $ 19.7 British Pound Sterling (9.5 ) — (9.5 ) — 11.7 11.7 Korean Won (5.5 ) — (5.5 ) — 4.4 4.4 Taiwan Dollar (5.0 ) — (5.0 ) (0.9 ) 5.7 4.8 Euro — 27.2 27.2 (30.6 ) — (30.6 ) Singapore Dollar — 15.0 15.0 — — — Total $ (71.9 ) $ 42.2 $ (29.7 ) $ (31.5 ) $ 41.5 $ 10.0
Schedule of Derivative Instruments in Statement of Financial Position at Fair Value	The following table summarizes the fair value of derivative instruments as of December 31, 2015 and 2014: Balance Sheet Location December 31, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 109 $ 220 Foreign exchange contracts Other current liabilities (146 ) (369 ) Total derivatives $ (37 ) $ (149 )
Schedule of Effect of Derivative Instruments on Statement of Operations Recognized	The following table summarizes the effect of derivative instruments in the statement of operations recognized for the years ended December 31, 2015, 2014 and 2013. The table does not reflect the corresponding gains and losses from the remeasurement of the monetary assets and liabilities denominated in foreign currencies. For the years ended December 31, 2015, 2014, and 2013, gains (losses) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $2.5 million, $(0.9) million, and $(6.9) million, respectively. Location of Losses (Gains) December 31, December 31, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ 3,047 $ 237 $ (5,933 ) Total derivatives $ 3,047 $ 237 $ (5,933 )

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Components of Convertible Senior Notes	For the year ended December 31, December 31, (in thousands) Contractual interest expense on the coupon $ — $ 1,757 Amortization of the discount component and debt issue fees recognized as interest expense — 4,493 Total interest expense on the convertible debt $ — $ 6,250

Accumulated Other Comprehensi37

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2015
Changes in Accumulated Other Comprehensive Income	Changes in accumulated other comprehensive income, which is presented net of tax, consists of the following: Foreign Unrealized Retirement Total (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 $1,449 — 2,417 — 2,417 Amounts reclassified from accumulated other comprehensive income, net of tax of $(645), $(169) — (1,433 ) (295 ) (1,728 ) Net current period other comprehensive income, net of tax of $804, $(169) — 984 (295 ) 689 Balance at December 31, 2014, net of tax of $1,598, $(453) $ — $ 2,365 $ 2,324 $ 4,689 Other comprehensive loss before reclassifications, net of tax of $0, $(1,667) (8,759 ) (3,075 ) — (11,834 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $(390), $(169) — (704 ) (295 ) (999 ) Net current period other comprehensive loss, net of tax of $0, $(2,057), $(169) (8,759 ) (3,779 ) (295 ) (12,833 ) Balance at December 31, 2015, net of tax of $0, $(459), $(622) $ (8,759 ) $ (1,414 ) $ 2,029 $ (8,144 )
Reclassifications Out of Accumulated Other Comprehensive Income to Statement of Operations	Reclassifications out of accumulated other comprehensive income to the statement of operations for the years ended December 31, 2015, 2014 and 2013, were as follows: Details about Accumulated Other Comprehensive Income Components For the year ended Affected Line Item December 31, December 31, December 31, (in thousands) Available-for-sale marketable securities Unrealized gains, net of tax of $390, $645, $257 $ 704 $ 1,433 $ 447 Interest income Amortization of defined benefit pension and postretirement plans Prior service benefit, net of tax of $169, $169, $159 $ 295 $ 295 $ 276 (a) Total reclassifications, net of tax of $559, $814, $416 $ 999 $ 1,728 $ 723 Net income (a) The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note M: “Retirement Plans.”

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Changes in Carrying Amount of Goodwill by Segment	The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2015 and 2014 are as follows: Wireless Industrial System Semiconductor Total (in thousands) Balance at December 31, 2013: Goodwill $ 361,792 $ — $ 148,183 $ 260,540 $ 770,515 Accumulated impairment losses — — (148,183 ) (260,540 ) (408,723 ) ZTEC adjustment 27 — — — 27 AIT acquisition — — 10,516 — 10,516 Balance at December 31, 2014: Goodwill 361,819 — 158,699 260,540 781,058 Accumulated impairment losses (98,897 ) — (148,183 ) (260,540 ) (507,620 ) Universal Robots acquisition — 221,128 — — 221,128 Foreign currency translation adjustment — (6,153 ) — — (6,153 ) Balance at December 31, 2015: Goodwill 361,819 214,975 158,699 260,540 996,033 Accumulated impairment losses (98,897 ) — (148,183 ) (260,540 ) (507,620 ) $ 262,922 $ 214,975 $ 10,516 $ — $ 488,413
Schedule of Amortizable Intangible Assets	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets: December 31, 2015 Gross Accumulated Net Weighted (in thousands) Developed technology $ 379,778 $ 220,306 $ 159,472 6.0 years Customer relationships 110,340 63,718 46,622 7.9 years Tradenames and trademarks 52,396 18,879 33,517 9.5 years Non-compete agreement 320 100 220 4.0 years Customer backlog 170 170 — 0.3 years Total intangible assets $ 543,004 $ 303,173 $ 239,831 6.7 years December 31, 2014 Gross Accumulated Net Weighted (in thousands) Developed technology $ 345,513 $ 224,059 $ 121,454 6.2 years Customer relationships 146,635 93,998 52,637 7.7 years Tradenames and trademarks 30,414 14,205 16,209 9.0 years Non-compete agreement 320 20 300 4.0 years Customer backlog 170 170 — 0.3 years Total intangible assets $ 523,052 $ 332,452 $ 190,600 6.8 years
Schedule of Estimated Intangible Asset Amortization Expense	Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2016 $ 79,874 2017 71,133 2018 44,464 2019 23,611 2020 9,990 Thereafter 10,759

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Non-Cancelable Operating Lease Commitments	The following table reflects Teradyne’s non-cancelable operating lease commitments: Non-cancelable (in thousands) 2016 $ 15,665 2017 11,778 2018 9,559 2019 8,487 2020 7,222 Beyond 2021 16,009 Total $ 68,720

Net Income per Common Share (Ta

Net Income per Common Share (Tables)	12 Months Ended
	Dec. 31, 2015
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: 2015 2014 2013 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 206,477 $ 81,272 $ 164,947 Weighted average common shares-basic 211,544 202,908 190,772 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) — 5,013 23,341 Convertible note hedge warrant shares (2) — 12,562 18,795 Restricted stock units 1,130 1,092 1,127 Stock options 606 944 1,528 Employee stock purchase rights 41 31 36 Dilutive potential common shares 1,777 19,642 44,827 Weighted average common shares-diluted 213,321 222,550 235,599 Net income per common share-basic $ 0.98 $ 0.40 $ 0.86 Net income per common share-diluted $ 0.97 $ 0.37 $ 0.70 (1) Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $5.48, 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. (2) Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.67, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne’s call option on its common stock (convertible note hedge transaction) was excluded from the calculation of diluted shares because the effect was anti-dilutive. See Note G: “Debt” regarding the convertible note hedge transaction.

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Defined Benefit Pension Plans
Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligations	The December 31 balances of these defined benefit pension plans assets and obligations are shown below: 2015 2014 United States Foreign United States Foreign (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 367,619 $ 58,210 $ 293,912 $ 52,182 Service cost 2,462 1,006 2,218 897 Interest cost 13,142 1,444 12,875 1,837 Actuarial (gain) loss (13,221 ) 7,498 72,596 8,975 Benefits paid (18,885 ) (859 ) (13,982 ) (1,265 ) Curtailment — (634 ) — — Plan participants’ contributions — 64 — 88 Non-U.S. currency movement — (4,439 ) — (4,504 ) End of year 351,117 62,290 367,619 58,210 Change in plan assets: Fair value of plan assets: Beginning of year 316,072 29,511 256,373 25,756 Company contributions 10,517 808 31,753 1,168 Plan participants’ contributions — 64 — 88 Actual return on plan assets (9,300 ) (136 ) 41,928 5,192 Benefits paid (18,885 ) (859 ) (13,982 ) (1,265 ) Admin expenses paid — (43 ) — — Non-U.S. currency movement — (1,204 ) — (1,428 ) End of year 298,404 28,141 316,072 29,511 Funded status $ (52,713 ) $ (34,149 ) $ (51,547 ) $ (28,699 )
Amounts Recorded Within Statement of Financial Position	The following table provides amounts recorded within the account line items of the statement of financial position as of December 31: 2015 2014 United Foreign United Foreign (in thousands) Retirement plans assets $ 636 $ — $ 3,090 $ 9,806 Accrued employees’ compensation and withholdings (2,564 ) (695 ) (2,492 ) (906 ) Retirement plans liabilities (50,785 ) (33,454 ) (52,145 ) (37,599 ) Funded status $ (52,713 ) $ (34,149 ) $ (51,547 ) $ (28,699 )
Amounts Recognized in Accumulated Other Comprehensive Income	The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2015 2014 United States Foreign United States Foreign (in thousands) Prior service cost, before tax $ 224 $ — $ 358 $ — Deferred taxes 479 — 429 — Total recognized in other comprehensive income, net of tax $ 703 $ — $ 787 $ —
Pension Plans with Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets	Information for pension plans with an accumulated benefit obligation in excess of plan assets as of December 31: 2015 2014 United States Foreign United States Foreign (in millions) Projected benefit obligation $ 53.3 $ 35.2 $ 54.6 $ 39.5 Accumulated benefit obligation 47.3 29.5 48.5 32.7 Fair value of plan assets — 1.0 — 1.0
Net Periodic Pension and Postretirement Benefit Costs	For the years ended December 31, 2015, 2014 and 2013, Teradyne’s net periodic pension cost (income) was comprised of the following: 2015 2014 2013 United Foreign United Foreign United Foreign (in thousands) Components of Net Periodic Pension Cost (Income): Service cost $ 2,462 $ 1,006 $ 2,218 $ 897 $ 2,393 $ 1,034 Interest cost 13,142 1,444 12,875 1,837 11,318 1,948 Expected return on plan assets (14,517 ) (781 ) (12,500 ) (868 ) (13,632 ) (959 ) Amortization of prior service cost 134 — 135 — 164 — Net actuarial loss (gain) 10,596 8,415 43,168 4,651 (7,063 ) (1,252 ) Curtailment — (634 ) — — — — Total net periodic pension cost (income) $ 11,817 $ 9,450 $ 45,896 $ 6,517 $ (6,820 ) $ 771 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service cost (134 ) — (135 ) — (164 ) — Total recognized in other comprehensive income (134 ) — (135 ) — (164 ) — Total recognized in net periodic pension cost (income) and other comprehensive income $ 11,683 $ 9,450 $ 45,761 $ 6,517 $ (6,984 ) $ 771
Weighted Average Assumptions to Determine Net Periodic Cost and Benefit Obligation	Weighted Average Assumptions to Determine Net Periodic Pension Cost at January 1: 2015 2014 2013 United States Foreign United States Foreign United States Foreign Discount rate 3.7 % 2.6 % 4.5 % 3.8 % 3.6 % 3.7 % Expected return on plan assets 4.8 2.6 5.0 3.4 5.0 3.7 Salary progression rate 2.9 3.2 3.0 3.5 3.0 3.5 Weighted Average Assumptions to Determine Pension Obligations at December 31: 2015 2014 United States Foreign United States Foreign Discount rate 4.0 % 2.3 % 3.7 % 2.6 % Salary progression rate 2.7 3.2 2.9 3.2
Weighted Average Pension Asset Allocations by Category	Teradyne’s weighted average pension asset allocation at December 31, 2015 and 2014, by asset category is as follows: 2015 2014 United States Foreign United States Foreign Fixed income securities 88.6 % — % 83.3 % 77.3 % Equity securities 9.8 — 15.4 19.0 Other 1.6 100.0 1.3 3.7 100.0 % 100.0 % 100.0 % 100.0 %
Target Asset Allocation and Index for Each Asset Category	The target asset allocation and the index for each asset category for the U.S. Plan, per the investment policy, are as follows: Asset Category: Policy Index: Target U.S. corporate fixed income Barclays U.S. Corporate A or Better Index 76 % Global equity MSCI World Minimum Volatility Index 10 U.S. government fixed income Barclays U.S. Long Government Bond Index 8 High yield fixed income Barclays U.S. Corporate High Yield 2% Issuer Cap Index 5 Cash Citigroup Three Month U.S. Treasury Bill Index 1
Changes in Fair Value of Pension Assets	The fair value of pension plan assets by asset category and by level at December 31, 2015 and December 31, 2014 were as follows: December 31, 2015 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 240,695 $ — $ 240,695 $ — $ — $ — $ — U.S. government securities — 23,761 — 23,761 — — — — Global equity — 29,193 — 29,193 — — — — Group annuity insurance contracts — — 2,982 2,982 — — 26,410 26,410 Other — — — — — 1,029 — 1,029 Cash and cash equivalents 1,773 — — 1,773 702 — — 702 Total $ 1,773 $ 293,649 $ 2,982 $ 298,404 $ 702 $ 1,029 $ 26,410 $ 28,141 December 31, 2014 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 193,741 $ — $ 193,741 $ — $ — $ — $ — U.S. government securities — 65,830 — 65,830 — — — — U.K. government securities — — — — — 22,811 — 22,811 Asset backed securities — 3,747 — 3,747 — — — — U.S. equity (large cap) — 33,970 — 33,970 — — — — International equity — 14,631 — 14,631 — 5,610 — 5,610 Group annuity insurance contracts — — 2,990 2,990 — — — — Other — 65 — 65 — 957 — 957 Cash and cash equivalents 1,098 — — 1,098 133 — — 133 Total $ 1,098 $ 311,984 $ 2,990 $ 316,072 $ 133 $ 29,378 $ — $ 29,511
Expected Future Benefit Payments	Future benefit payments are expected to be paid as follows: United States Foreign (in thousands) 2016 $ 19,696 $ 1,062 2017 18,346 1,032 2018 18,836 1,021 2019 19,453 1,477 2020 20,129 1,266 2021-2025 109,860 8,561
Postretirement Benefit Plans
Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligations	The December 31 balances of the postretirement assets and obligations are shown below: 2015 2014 (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 7,162 $ 9,019 Service cost 48 59 Interest cost 237 335 Actuarial (gain) loss (648 ) (1,255 ) Benefits paid (769 ) (996 ) End of year 6,030 7,162 Change in plan assets: Fair value of plan assets: Beginning of year — — Company contributions 769 996 Benefits paid (769 ) (996 ) End of year — — Funded status $ (6,030 ) $ (7,162 )
Amounts Recorded Within Statement of Financial Position	The following table provides amounts recorded within the account line items of financial position as of December 31: 2015 2014 (in thousands) Accrued employees’ compensation and withholdings $ (692 ) $ (780 ) Retirement plans liability (5,338 ) (6,382 ) Funded status $ (6,030 ) $ (7,162 )
Amounts Recognized in Accumulated Other Comprehensive Income	The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2015 2014 (in thousands) Prior service credit, before tax $ (1,632 ) $ (2,230 ) Deferred taxes (1,100 ) (882 ) Total recognized in other comprehensive income, net of tax $ (2,732 ) $ (3,112 )
Net Periodic Pension and Postretirement Benefit Costs	For the years ended December 31, 2015, 2014 and 2013, Teradyne’s net periodic postretirement benefit income was comprised of the following: 2015 2014 2013 (in thousands) Components of Net Periodic Postretirement Benefit Income: Service cost $ 48 $ 59 $ 75 Interest cost 237 335 342 Amortization of prior service credit (598 ) (598 ) (598 ) Net actuarial gain (648 ) (1,255 ) (2,025 ) Total net periodic postretirement benefit income (961 ) (1,459 ) (2,206 ) Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service credit 598 598 598 Total recognized in other comprehensive income 598 598 598 Total recognized in net periodic postretirement benefit income and other comprehensive income $ (363 ) $ (861 ) $ (1,608 )
Weighted Average Assumptions to Determine Net Periodic Cost and Benefit Obligation	Weighted Average Assumptions to Determine Net Periodic Postretirement Benefit Income as of January 1: 2015 2014 2013 Discount rate 3.5 % 4.1 % 3.1 % Initial health care cost trend rate 7.5 8.0 8.5 Ultimate health care cost trend rate 5.0 5.0 5.0 Year in which ultimate health care cost trend rate is reached 2022 2020 2020 Weighted Average Assumptions to Determine Postretirement Benefit Obligation as of December 31: 2015 2014 2013 Discount rate 3.9 % 3.5 % 4.1 % Initial medical trend 7.5 7.5 8.0 Ultimate health care trend 5.0 5.0 5.0 Medical cost trend rate decrease to ultimate rate in year 2023 2022 2020
Expected Future Benefit Payments	Future benefit payments are expected to be paid as follows: Benefit Payments (in thousands) 2016 $ 692 2017 587 2018 553 2019 492 2020 410 2021-2025 1,654
One Percentage Point Change in Assumed Health Care Cost Trend Rates for Year	A one percentage point change in the assumed health care cost trend rates for the year ended December 31, 2015, would have the following effects: 1 Percentage 1 Percentage (in thousands) Effect on total service and interest cost components $ 3 $ (2 ) Effect on postretirement benefit obligations 59 (56 )
Group Annuity Insurance Contracts
Changes in Fair Value of Pension Assets	The table below indicates the change in value related to these level 3 assets during 2015 and 2014: Group Annuity Insurance Contracts (in thousands) Balance at December 31, 2013 $ 2,985 Interest and market value adjustments 152 Benefits paid (125 ) Other (22 ) Balance at December 31, 2014 $ 2,990 Purchases of group annuity insurance contracts 27,313 Interest and market value adjustments (825 ) Benefits paid (67 ) Other (19 ) Balance at December 31, 2015 $ 29,392

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions	The fair value was estimated using the Monte Carlo simulation model with the following assumptions: 2015 2014 Risk-free interest rate 0.77 % 0.75 % Teradyne volatility-historical 28.2 % 36.1 % Philadelphia Semiconductor Index volatility-historical 19.7 % 24.6 % Dividend yield 1.33 % 1.25 %
Stock Compensation Plan Activity	Stock compensation plan activity for the years 2015, 2014 and 2013 follows: 2015 2014 2013 (in thousands) Restricted Stock Units: Non-vested at January 1 4,352 4,636 4,970 Awarded 1,681 1,870 2,110 Vested (1,679 ) (1,965 ) (2,322 ) Forfeited (284 ) (189 ) (122 ) Non-vested at December 31 4,070 4,352 4,636 Stock Options: Outstanding at January 1 1,507 2,706 3,841 Granted 132 89 213 Exercised (518 ) (1,248 ) (1,220 ) Forfeited — (38 ) (104 ) Expired — (2 ) (24 ) Outstanding at December 31 1,121 1,507 2,706 Vested and expected to vest at December 31 1,121 1,507 2,694 Exercisable at December 31 779 1,089 1,814
Share Based Compensation Total Shares Available	Total shares available for the years 2015, 2014 and 2013: 2015 2014 2013 (in thousands) Shares available: Available for grant at January 1 12,443 14,213 6,414 Options granted (132 ) (89 ) (213 ) Restricted stock units awarded (1,681 ) (1,870 ) (2,110 ) Restricted stock units forfeited 284 189 122 Additional shares reserved — — 10,000 Available for grant at December 31 10,914 12,443 14,213
Weighted-Average Restricted Stock Unit Award Date Fair Value	Weighted average restricted stock unit award date fair value information for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Non-vested at January 1 $ 17.24 $ 15.60 $ 12.72 Awarded 17.36 18.41 16.62 Vested 16.85 14.38 10.40 Forfeited 17.08 16.97 15.48 Non-vested at December 31 $ 17.46 $ 17.24 $ 15.60
Restricted Stock Unit Awards Aggregate Intrinsic Value	Restricted stock unit awards aggregate intrinsic value information at December 31 for the years 2015, 2014 and 2013 follows: 2015 2014 2013 (in thousands) Outstanding $ 84,129 $ 86,113 $ 81,680 Expected to vest 79,611 81,582 77,388
Restricted Stock Units Weighted Average Remaining Contractual Terms	Restricted stock units weighted average remaining contractual terms (in years) information at December 31, for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Outstanding 1.09 1.11 1.14 Expected to vest 1.08 1.10 1.13
Weighted Average Stock Options Exercise Price	Weighted average stock options exercise price information for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Outstanding at January 1 $ 7.89 $ 6.29 $ 4.64 Options granted 18.10 19.16 16.56 Options exercised 5.49 5.34 3.28 Options forfeited 8.67 3.59 2.57 Options cancelled 3.28 2.21 8.05 Outstanding at December 31 10.21 7.89 6.29 Exercisable at December 31 6.92 5.00 4.55
Stock Option Aggregate Intrinsic Value Information	Stock option aggregate intrinsic value information for the years ended December 31, 2015, 2014 and 2013 follows: 2015 2014 2013 (in thousands) Exercised $ 7,255 $ 17,847 $ 16,848 Outstanding 11,729 17,936 30,673 Vested and expected to vest 11,729 17,936 30,512 Exercisable 10,716 16,101 23,707
Stock Options Weighted Average Remaining Contractual Terms	Stock options weighted average remaining contractual terms (in years) information at December 31, for the years 2015, 2014 and 2013 follows: 2015 2014 2013 Outstanding 4.2 4.5 4.9 Vested and expected to vest 4.2 4.5 4.9 Exercisable 3.9 4.2 4.3
Significant Option Groups Outstanding	Significant option groups outstanding at December 31, 2015 and related weighted average price and remaining contractual life information follow: Options Outstanding Options Exercisable Range Of Exercise Prices Weighted- Shares Weighted- Shares Weighted- (shares in thousands) $1.48 – $2.67 4.58 416 $ 2.33 416 $ 2.33 $3.23 – $7.71 2.71 139 4.60 139 4.60 $11.37 – $16.95 3.54 345 16.63 202 16.62 $18.10 – $19.16 5.68 221 18.53 22 19.16 1,121 $ 10.21 779 $ 6.92
Effect to Income (Loss) from Operations for Recording Stock-Based Compensation	The effect to income from operations for recording stock-based compensation for the years ended December 31 was as follows: 2015 2014 2013 (in thousands) Cost of revenues $ 3,065 $ 3,675 $ 4,338 Engineering and development 9,362 10,146 12,452 Selling and administrative 18,024 26,486 19,822 Stock-based compensation 30,451 40,307 36,612 Income tax benefit (8,528 ) (11,537 ) (9,762 ) Total stock-based compensation expense after income taxes $ 21,923 $ 28,770 $ 26,850
Stock Options
Fair Value of Stock Options Using Assumptions	The fair value of the stock options at grant date was estimated using the Black-Scholes option-pricing model with the following assumptions: 2015 2014 2013 Expected life (years) 4.0 4.0 4.0 Risk-free interest rate 1.1 % 1.2 % 0.6 % Volatility-historical 33.4 % 38.8 % 46.8 % Dividend yield 1.33 % 1.25 % 0.0 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income (loss) Before Income Taxes	The components of income (loss) before income taxes and the provision for income taxes as shown in the consolidated statements of operations were as follows: 2015 2014 2013 (in thousands) Income (loss) before income taxes: U.S. $ 56,270 $ (151,889 ) $ 79,229 Non-U.S. 196,854 247,265 122,693 $ 253,124 $ 95,376 $ 201,922 Provision (benefit) for income taxes: Current: U.S. Federal $ 16,635 $ 5,197 $ 18,051 Non-U.S. 35,707 28,157 22,509 State 1,429 678 (269 ) 53,771 34,032 40,291 Deferred: U.S. Federal (574 ) (20,449 ) (1,692 ) Non-U.S. (7,761 ) (404 ) (1,386 ) State 1,211 925 (238 ) (7,124 ) (19,928 ) (3,316 ) Total provision for income taxes: $ 46,647 $ 14,104 $ 36,975
Reconciliation of Effective Tax Rate	A reconciliation of the effective tax rate for the years 2015, 2014 and 2013 follows: 2015 2014 2013 U.S. statutory federal tax rate 35.0 % 35.0 % 35.0 % Foreign taxes (16.5 ) (58.1 ) (11.4 ) Goodwill impairment — 36.3 — U.S. research and development credit (3.0 ) (7.9 ) (7.2 ) Uncertain tax positions 2.1 7.9 4.2 Valuation allowance — — 0.4 State income taxes, net of federal tax benefit 0.4 (0.1 ) 0.1 Other, net 0.4 1.7 (2.8 ) 18.4 % 14.8 % 18.3 %
Deferred Tax Assets (Liabilities)	Significant components of Teradyne’s deferred tax assets (liabilities) as of December 31, 2015 and 2014 were as follows: 2015 2014 (in thousands) Deferred tax assets: Tax credits $ 44,684 $ 50,554 Pension liabilities 31,742 30,036 Inventory valuations 29,445 29,105 Accruals 26,563 23,323 Deferred revenue 10,232 10,242 Equity compensation 9,674 11,131 Net operating loss carryforwards 7,989 10,989 Vacation accrual 7,354 7,425 Other 502 1,725 Gross deferred tax assets 168,185 174,530 Less: valuation allowance (43,039 ) (41,737 ) Total deferred tax assets $ 125,146 $ 132,793 Deferred tax liabilities: Intangible assets $ (68,433 ) $ (64,871 ) Depreciation (20,541 ) (24,905 ) Marketable securities (458 ) (1,599 ) Total deferred tax liabilities $ (89,432 ) $ (91,375 ) Net deferred assets $ 35,714 $ 41,418
Operating Loss Carryforwards	At December 31, 2015, Teradyne had operating loss carryforwards that expire in the following years: U.S. Federal State Foreign (in thousands) 2016 $ — $ 925 $ — 2017 — 10,649 — 2018 — 8,563 — 2019 — 1,203 — 2020 — 269 — 2021-2025 4,870 35,777 — 2026-2030 — 39,411 — Beyond 2030 — 6,359 143 Non-expiring — — 8,202 Total $ 4,870 $ 103,156 $ 8,345
Unrecognized Tax Benefits	Teradyne’s gross unrecognized tax benefits for the years ended December 31, 2015, 2014 and 2013 were as follows: 2015 2014 2013 (in thousands) Beginning balance, as of January 1 $ 30,418 $ 21,203 $ 18,666 Additions: Tax positions for current year 6,626 8,414 4,586 Tax positions for prior years 792 3,781 2,112 Reductions: Tax positions for prior years (708 ) (2,480 ) (4,161 ) Settlements with tax authorities (336 ) (500 ) — Ending balance as of December 31 $ 36,792 $ 30,418 $ 21,203

Operating Segment, Geographic44

Operating Segment, Geographic and Significant Customer Information (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Information	Semiconductor Wireless Test System Industrial Corporate Consolidated (in thousands) 2015 Revenues $ 1,201,530 $ 184,572 $ 211,584 $ 41,892 $ — $ 1,639,578 Income (loss) before taxes (1)(2) 260,154 (13,830 ) 25,101 (7,574 ) (10,727 ) 253,124 Total assets (3) 610,869 427,880 102,547 344,260 1,063,118 2,548,674 Property additions 79,052 3,133 6,228 1,465 — 89,878 Depreciation and amortization expense 64,415 53,440 4,390 14,500 4,027 140,772 2014 Revenues $ 1,300,790 $ 184,535 $ 162,499 $ — $ — $ 1,647,824 Income (loss) before taxes (1)(2) 255,803 (116,196 ) 12,116 — (56,347 ) 95,376 Total assets (3) 580,501 478,974 95,105 — 1,383,940 2,538,520 Property additions 159,783 3,730 5,469 — — 168,982 Depreciation and amortization expense 84,990 53,308 5,399 — 8,847 152,544 2013 Revenues $ 1,023,041 $ 251,871 $ 153,021 $ — $ — $ 1,427,933 Income before taxes (1)(2) 153,797 23,153 3,115 — 21,857 201,922 Total assets (3) 632,840 645,001 79,983 — 1,272,000 2,629,824 Property additions 94,303 5,358 7,070 — — 106,731 Depreciation and amortization expense 72,472 51,675 5,180 — 21,360 150,687 (1) Interest income, interest expense, other (income) expense, net, contingent consideration adjustments and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges and goodwill impairment charges. (3) Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.
Revenues by Country	Information as to Teradyne’s revenues by country is as follows: 2015 2014 2013 (in thousands) Revenues from customers (1): Taiwan $ 436,389 $ 495,942 $ 265,472 China 264,898 292,145 323,564 United States 217,386 213,104 230,178 Japan 128,228 63,761 81,806 Korea 120,224 145,608 119,286 Europe 111,903 111,043 90,797 Singapore 105,216 119,421 114,765 Philippines 96,103 68,662 63,392 Malaysia 76,707 83,910 86,900 Thailand 59,104 44,117 32,209 Rest of the World 23,420 10,111 19,564 $ 1,639,578 $ 1,647,824 $ 1,427,933 (1) Revenues attributable to a country are based on location of customer site.
Long-Lived Assets by Geographic Area	Long-lived assets by geographic area: United Foreign(1) Total (in thousands) December 31, 2015 $ 198,424 $ 74,990 $ 273,414 December 31, 2014 $ 206,334 $ 122,704 $ 329,038 (1) As of December 31, 2015 and 2014, long-lived assets attributable to Singapore were $39.9 million and $99.2 million, respectively.
Semiconductor Test
Schedule of Segment Reporting Information by Segment Charges	Included in the Semiconductor Test segment are charges in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory charge $ 10,508 $ 14,389 $ 5,218 Restructuring and other 499 490 1,016
System Test
Schedule of Segment Reporting Information by Segment Charges	Included in the System Test segment are charges in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory charge $ 8,324 $ 2,125 $ 4,168 Restructuring and other 1,037 742 1,431
Wireless Test
Schedule of Segment Reporting Information by Segment Charges	Included in the Wireless Test segment are charges in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory charge $ 2,500 $ 5,679 $ 7,206 Restructuring and other — 565 82 Goodwill impairment charge — 98,897 —
Industrial Automation
Schedule of Segment Reporting Information by Segment Charges	Included in the Industrial Automation segment are charges in the following account: For the Year Ended December 31, 2015 2014 2013 (in thousands) Cost of revenues—inventory step-up (1) $ 1,567 $ — $ — (1) Included in the cost of revenues for the years ended December 31, 2015 is the cost for purchase accounting inventory step-up.
Corporate And Eliminations
Schedule of Segment Reporting Information by Segment Charges	Included in the Corporate and Eliminations segment are charges and credits in the following accounts: For the Year Ended December 31, 2015 2014 2013 (in thousands) Restructuring and other—Universal Robots contingent consideration adjustment $ 5,339 $ — $ — Restructuring and other—ZTEC contingent consideration adjustment (1,600 ) (630 ) — Restructuring and other—AIT contingent consideration adjustment (1,250 ) — — Restructuring and other—acquisition costs 1,104 372 — Restructuring and other — 198 (449 ) Other (income) expense, net—gain from the sale of an equity investment (5,406 ) — (34,212 ) Selling and administrative—stock based compensation expense (1) — 6,598 — (1) Expense related to the January 2014 retirement of Teradyne’s former chief executive officer; see Note N: “Stock-Based Compensation.”

Supplementary Information (Tabl

Supplementary Information (Tables)	12 Months Ended
	Dec. 31, 2015
Consolidated Quarterly Statements of Operations	The following sets forth certain unaudited consolidated quarterly statements of operations data for each of Teradyne’s last eight quarters. In management’s opinion, this quarterly information reflects all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement for the periods presented. Such quarterly results are not necessarily indicative of future results of operations and should be read in conjunction with the audited consolidated financial statements of Teradyne and the notes thereto included elsewhere herein. 2015 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (3) (4) (1)(2) (in thousands, except per share amounts) Revenues: Products $ 272,325 $ 437,243 $ 386,488 $ 244,510 Services 70,076 75,496 79,506 73,934 Total revenues 342,401 512,739 465,994 318,444 Cost of revenues: Cost of products 118,996 181,491 170,963 120,322 Cost of services 30,982 32,680 36,405 32,096 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 149,978 214,171 207,368 152,418 Gross profit 192,423 298,568 258,626 166,026 Operating expenses: Engineering and development 71,450 75,832 74,027 70,941 Selling and administrative 72,041 77,073 77,481 79,718 Acquired intangible assets amortization 13,808 15,258 20,053 19,911 Restructuring and other — (385 ) 261 5,204 Total operating expenses 157,299 167,778 171,822 175,774 Income (loss) from operations 35,124 130,790 86,804 (9,748 ) Non-operating (income) expense: Interest income (1,816 ) (1,674 ) (1,708 ) (2,017 ) Interest expense 162 444 508 762 Other (income) expense, net (5,660 ) (116 ) 596 364 Income (loss) before income taxes 42,438 132,136 87,408 (8,857 ) Income tax provision (benefit) 9,651 29,257 15,955 (8,216 ) Net income (loss) $ 32,787 $ 102,879 $ 71,453 $ (641 ) Net income (loss) per common share—basic $ 0.15 $ 0.48 $ 0.34 $ (0.00 ) Net income (loss) per common share—diluted $ 0.15 $ 0.48 $ 0.34 $ (0.00 ) Cash dividend declared per common share $ 0.06 $ 0.06 $ 0.06 $ 0.06 (1) Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration. (2) In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: “Accounting Policies” for a discussion of our accounting policy. (3) Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration. (4) Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration. 2014 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (1)(2) (1)(3)(4) (in thousands, except per share amounts) Revenues: Products $ 255,386 $ 452,488 $ 402,987 $ 253,162 Services 65,624 73,079 75,023 70,074 Total revenues 321,010 525,567 478,010 323,236 Cost of revenues: Cost of products 124,448 202,411 182,591 131,337 Cost of services 29,515 32,743 34,298 31,673 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 153,963 235,154 216,889 163,010 Gross profit 167,047 290,413 261,121 160,226 Operating expenses: Engineering and development 67,085 73,414 71,953 79,188 Selling and administrative 78,003 77,489 73,064 91,157 Goodwill impairment — — — 98,897 Acquired intangible assets amortization 18,271 18,271 18,271 15,957 Restructuring and other — 572 (405 ) 1,198 Total operating expenses 163,359 169,746 162,883 286,397 Income (loss) from operations 3,688 120,667 98,238 (126,171 ) Non-operating (income) expense: Interest income (1,036 ) (1,266 ) (1,922 ) (2,035 ) Interest expense 6,417 159 144 214 Other (income) expense, net 180 382 (654 ) 463 (Loss) income before income taxes (1,873 ) 121,392 100,670 (124,813 ) Income tax (benefit) provision (2,802 ) 20,187 17,721 (21,002 ) Net income (loss) $ 929 $ 101,205 $ 82,949 $ (103,811 ) Net income (loss) per common share—basic $ 0.00 $ 0.52 $ 0.40 $ (0.48 ) Net income (loss) per common share—diluted $ 0.00 $ 0.47 $ 0.38 $ (0.48 ) Cash dividend declared per common share $ 0.00 $ 0.06 $ 0.06 $ 0.06 (1) Dividends declared by Teradyne’s Board of Directors were paid in the second, third and fourth quarters of 2014. (2) Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration. (3) In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: “Accounting Policies” for a discussion of our accounting policy. (4) In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.

The Company - Additional inform

The Company - Additional information (Detail) - Universal Robots	Jun. 11, 2015USD ($)
Business Acquisition [Line Items]
Cash paid to acquire outstanding common and preferred stock	$ 283,800,000
Arrangement range of outcomes value high	$ 65,000,000

Deferred Revenue and Customer A

Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred Revenue Arrangement
Extended warranty	$ 46,499	$ 43,300	$ 34,909	$ 28,044
Equipment maintenance and training	30,616	30,500
Customer advances	17,456	8,875
Undelivered elements and other	16,701	8,857
Total deferred revenue and customer advances	$ 111,272	$ 91,532

Warranty Accrual Included in Ot

Warranty Accrual Included in Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 8,942	$ 6,660	$ 9,786
Acquisition	409
Accruals for warranties issued during the period	11,539	15,406	10,574
Accruals related to pre-existing warranties	(3,159)	(2,008)	(3,534)
Settlements made during the period	(10,806)	(11,116)	(10,166)
Balance at end of period	$ 6,925	$ 8,942	$ 6,660

Extended Product Warranty Inclu

Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 43,300	$ 34,909	$ 28,044
Acquisition	870
Deferral of new extended warranty revenue	28,549	29,519	20,630
Recognition of extended warranty deferred revenue	(26,220)	(21,128)	(13,765)
Balance at end of period	$ 46,499	$ 43,300	$ 34,909

Schedule of Prepayments (Detail

Schedule of Prepayments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Prepaid And Other Current Assets [Line Items]
Contract manufacturer prepayments	$ 66,283	$ 65,972
Prepaid maintenance and other services	8,481	7,343
Prepaid taxes	3,781	11,462
Other prepayments	12,974	11,042
Total prepayments	$ 91,519	$ 95,819

Useful Lives of Assets (Detail)

Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2015
Buildings
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	40 years
Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years
Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	10 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful lives, description	Lesser of lease term or 10 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	10 years
Test Systems Manufactured Internally
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	6 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	3 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years
Software | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	3 years
Software | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years

Accounting Policies - Additiona

Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Depreciation over life to cost of revenues and selling and administrative expenses, years	6 years
Net book value of internally manufactured test systems sold	$ 50.7	$ 9.7	$ 9
Advertising costs	3.3	1.9	1.7
Gains and losses on foreign exchange contracts	$ 2.5	$ (0.9)	$ (6.9)
Convertible Notes
Summary Of Significant Accounting Policies [Line Items]
Initial debt conversion price	$ 5.48
Shares that would be issued upon conversion	34.7
Convertible Notes Hedge Warrant
Summary Of Significant Accounting Policies [Line Items]
Initial debt conversion price	$ 7.67
Shares that would be issued upon conversion	34.7

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($)	Jun. 11, 2015	Oct. 31, 2014	Oct. 25, 2013	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Payments of contingent consideration											$ 388,000
Goodwill				$ 273,438,000			$ 488,413,000	$ 488,413,000	$ 488,413,000	$ 273,438,000
ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Total purchase price			$ 17,308,000
Cash paid to acquire outstanding common and preferred stock			15,100,000
Contingent consideration			2,200,000
Revenues					$ 400,000
Income (loss) before income taxes					$ (800,000)
Net income											163,394,000
Goodwill			12,520,000
Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total purchase price		$ 21,243,000
Cash paid to acquire outstanding common and preferred stock		19,400,000
Contingent consideration		1,800,000
Arrangement range of outcomes value high		$ 1,100,000
Revenues				600,000
Income (loss) before income taxes				$ (800,000)
Net income										82,169,000	$ 164,087,000
Discount rate		4.70%
Goodwill, expected tax deduction		$ 10,500,000
Goodwill		$ 10,516,000
Universal Robots
Business Acquisition [Line Items]
Total purchase price	$ 315,437,000
Cash paid to acquire outstanding common and preferred stock	283,800,000
Contingent consideration	31,600,000
Arrangement range of outcomes value high	65,000,000
Decrease in goodwill							(5,400,000)
Contingent consideration adjustment							(2,200,000)
Increase in intangible assets							1,600,000
Decrease in acquired liabilities							$ (1,600,000)
Goodwill, not deductible for tax purposes	221,100,000
Revenues								41,900,000
Income (loss) before income taxes								$ (7,600,000)
Net income									199,784,000	61,078,000
Goodwill	$ 221,128,000
Universal Robots | Fair Value Adjustment to Inventory
Business Acquisition [Line Items]
Net income									(1,600,000)	1,600,000
Universal Robots | Acquisition Related Costs
Business Acquisition [Line Items]
Net income									$ (1,000,000)	$ 1,000,000
Universal Robots | Scenario, Forecast
Business Acquisition [Line Items]
Payments of contingent consideration						$ 15,000,000
EBITDA contingent consideration amount, percentage						100.00%
Maximum | ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Contingent consideration			$ 5,000,000

Allocation of Final Purchase Pr

Allocation of Final Purchase Price (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Jun. 11, 2015	Dec. 31, 2014	Oct. 31, 2014	Oct. 25, 2013
Business Acquisition [Line Items]
Goodwill	$ 488,413		$ 273,438
Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Goodwill				$ 10,516
Intangible assets				9,080
Current assets				2,452
Non-current assets				359
Accounts payable and current liabilities				(1,164)
Total purchase price				$ 21,243
Universal Robots
Business Acquisition [Line Items]
Goodwill		$ 221,128
Intangible assets		121,590
Current assets		10,853
Non-current assets		3,415
Accounts payable and current liabilities		(11,976)
Long-term deferred tax liabilities		(26,653)
Long-term other liabilities		(2,920)
Total purchase price		$ 315,437
ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Goodwill					$ 12,520
Intangible assets					4,870
Cash					79
Other current assets					1,612
Non-current assets					1,757
Accounts payable and current liabilities					(1,811)
Long-term deferred tax liabilities					(1,719)
Total purchase price					$ 17,308

Components of Intangible Assets

Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date (Detail) - USD ($) $ in Thousands	Jun. 11, 2015	Oct. 31, 2014	Oct. 25, 2013	Dec. 31, 2015	Dec. 31, 2014
ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Total intangible assets, fair value			$ 4,870
Total intangible assets, estimated useful life, years			5 years 3 months 18 days
Universal Robots
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 121,590			$ 121,590
Total intangible assets, estimated useful life, years	5 years 7 months 6 days
Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total intangible assets, fair value		$ 9,080			$ 9,080
Total intangible assets, estimated useful life, years		4 years 9 months 18 days
Developed technology | ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Total intangible assets, fair value			$ 3,500
Total intangible assets, estimated useful life, years			5 years
Developed technology | Universal Robots
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 89,240
Total intangible assets, estimated useful life, years	4 years 10 months 24 days
Developed technology | Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total intangible assets, fair value		$ 2,580
Total intangible assets, estimated useful life, years		4 years 9 months 18 days
Customer Relationships | ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Total intangible assets, fair value			$ 1,370
Total intangible assets, estimated useful life, years			6 years
Customer Relationships | Universal Robots
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 9,430
Total intangible assets, estimated useful life, years	2 years
Customer Relationships | Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total intangible assets, fair value		$ 5,630
Total intangible assets, estimated useful life, years		5 years
Trademarks and tradenames | Universal Robots
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 22,920
Total intangible assets, estimated useful life, years	10 years
Trademarks and tradenames | Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total intangible assets, fair value		$ 380
Total intangible assets, estimated useful life, years		5 years
Non-compete Agreements | Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total intangible assets, fair value		$ 320
Total intangible assets, estimated useful life, years		4 years
Customer backlog | Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Total intangible assets, fair value		$ 170
Total intangible assets, estimated useful life, years		3 months 18 days

Pro Forma Results Under Acquisi

Pro Forma Results Under Acquisition (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Universal Robots
Business Acquisition [Line Items]
Revenue	$ 1,657,626	$ 1,686,689
Net income	$ 199,784	$ 61,078
Net income per common share, basic	$ 0.94	$ 0.30
Net income per common share, diluted	$ 0.94	$ 0.27
Avionics Interface Technologies, LLC
Business Acquisition [Line Items]
Revenue		$ 1,655,038	$ 1,434,699
Net income		$ 82,169	$ 164,087
Net income per common share, basic		$ 0.40	$ 0.86
Net income per common share, diluted		$ 0.37	$ 0.70
ZTEC Instruments, Inc.
Business Acquisition [Line Items]
Revenue			$ 1,431,270
Net income			$ 163,394
Net income per common share, basic			$ 0.86
Net income per common share, diluted			$ 0.69

Property Plant and Equipment (D

Property Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Land	$ 16,561	$ 16,561
Buildings	108,797	108,671
Machinery and equipment	595,445	659,743
Furniture and fixtures, and software	82,612	77,566
Leasehold improvements	43,328	31,981
Construction in progress	2,630	2,508
Property, Plant and Equipment, Gross, Total	849,373	897,030
Less: accumulated depreciation	575,959	567,992
Property, plant and equipment, net	$ 273,414	$ 329,038

Property, Plant and Equipment -

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciation of property, plant and equipment	$ 68,181	$ 73,390	$ 57,317
Machinery and equipment	595,445	659,743
Accumulated depreciation	575,959	567,992
Test Systems Leased By Customers
Property, Plant and Equipment [Line Items]
Machinery and equipment	20,400	89,600
Accumulated depreciation	$ 8,500	$ 19,900

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended				12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized loss					$ 400,000	$ 0	$ 0
Available-for-sale securities, realized gain					1,700,000	2,400,000	1,000,000
Payments of contingent consideration							388,000
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses			$ 583,076,000		601,660,000	583,076,000
Fair market value of investments with unrealized losses greater than one year			2,300,000		900,000	2,300,000
Aggregate loss of investments with unrealized losses greater than one year					500,000	100,000
Fair market value of investments with unrealized losses less than one year			580,800,000		600,800,000	580,800,000
Aggregate loss of investments with unrealized losses less than one year					3,600,000	800,000
Goodwill, carrying value			781,058,000		996,033,000	781,058,000	770,515,000
Goodwill, impairment loss			98,897,000	[1],[2],[3]		98,897,000	0
Gains (losses) on foreign currency transactions					2,500,000	(900,000)	(6,900,000)
Realized (losses) gains on foreign currency contracts					(3,000,000)	(200,000)	5,900,000
Proceeds from sale of equity interest		$ 5,406,000			5,406,000		$ 34,212,000
Equity And Debt Mutual Funds
Financial Instruments and Fair Value [Line Items]
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses			1,234,000		2,560,000	1,234,000
Available for sale securities with out contractual maturity date					14,000,000
Foreign Currency Forward Contracts
Financial Instruments and Fair Value [Line Items]
Gains (losses) on foreign currency transactions					$ 0	(100,000)
Fair Value, Measurements, Nonrecurring
Financial Instruments and Fair Value [Line Items]
Goodwill, carrying value			372,300,000			372,300,000
Goodwill, fair value			$ 273,438,000			273,438,000
Goodwill, impairment loss						$ 98,897,000
Scenario, Forecast | Universal Robots
Financial Instruments and Fair Value [Line Items]
Payments of contingent consideration	$ 15,000,000
EBITDA contingent consideration amount, percentage	100.00%
Accounts Receivable | Customer 1 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage					10.00%
Accounts Receivable | Customer 2 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage						10.00%
[1]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[2]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[3]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

Schedule of Fair Value of Finan

Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	$ 743,624	$ 1,004,576
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	419,958	402,154
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	161,634	141,467
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,952	258,502
Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	43,394	49,036
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	20,308	140,638
Equity And Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	13,954	12,333
Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	424	446
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,008,329	1,298,832
Derivative assets	109	220
Total	1,008,438	1,299,052
Contingent consideration	37,436	3,350
Derivative liabilities	146	369
Total	37,582	3,719
Fair Value, Measurements, Recurring | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	213,336	111,471
Fair Value, Measurements, Recurring | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	51,369	182,785
Fair Value, Measurements, Recurring | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	419,958	402,154
Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	161,634	141,467
Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,952	258,502
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	43,394	49,036
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	20,308	140,638
Fair Value, Measurements, Recurring | Equity And Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	13,954	12,333
Fair Value, Measurements, Recurring | Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	424	446
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
Total	276,531	284,022
Total	276,531	284,022
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	213,336	111,471
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	49,241	160,218
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	13,954	12,333
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	731,798	1,014,810
Derivative assets	109	220
Total	731,907	1,015,030
Derivative liabilities	146	369
Total	146	369
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	2,128	22,567
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	419,958	402,154
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	161,634	141,467
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	83,952	258,502
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	43,394	49,036
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	20,308	140,638
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	424	446
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration	37,436	3,350
Total	$ 37,436	$ 3,350

Schedule of Reported Financial

Schedule of Reported Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,008,438	$ 1,299,052
Liabilities	37,582	3,719
Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	146	369
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	264,705	294,256
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	477,696	533,787
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	265,928	470,789
Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	109	220
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	15,500	895
Long-term other accrued liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		2,455
Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	21,936
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	276,531	284,022
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	262,577	271,689
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	13,954	12,333
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	731,907	1,015,030
Liabilities	146	369
Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	146	369
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	2,128	22,567
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	477,696	533,787
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	251,974	458,456
Significant Other Observable Inputs (Level 2) | Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	109	220
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	37,436	3,350
Significant Unobservable Inputs (Level 3) | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	15,500	895
Significant Unobservable Inputs (Level 3) | Long-term other accrued liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		$ 2,455
Significant Unobservable Inputs (Level 3) | Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	$ 21,936

Schedule of Changes in Fair Val

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 3,350	$ 2,230
Ending Balance	37,436	3,350
Avionics Interface Technologies, LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Acquisition		1,750
Fair value adjustment	(1,250)
ZTEC Instruments, Inc.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value adjustment	(1,600)	$ (630)
Universal Robots
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Acquisition	31,597
Fair value adjustment	$ 5,339

Quantitative Information Associ

Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail) - USD ($) $ in Thousands	Oct. 31, 2014	Dec. 31, 2015	Jun. 11, 2015
Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration			$ 31,600
Avionics Interface Technologies, LLC
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration	$ 1,800
Discount rate	4.70%
Monte Carlo simulation model | Revenue for the period July 1, 2015-December 31, 2017 | Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Target achievement, volatility		15.00%
Discount rate		5.50%
Monte Carlo simulation model | Revenue for the period July 1, 2015-December 31, 2018 | Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Target achievement, volatility		15.00%
Discount rate		5.50%
Monte Carlo simulation model | Significant Unobservable Inputs (Level 3) | Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration		$ 21,936
Income Approach Valuation Technique | Revenue for calendar year 2016 | Avionics Interface Technologies, LLC
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Target achievement, probability		48.00%
Discount rate		4.70%
Income Approach Valuation Technique | Significant Unobservable Inputs (Level 3) | Avionics Interface Technologies, LLC
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration		$ 500

Schedule of Carrying Amounts an

Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Marketable securities	$ 743,624	$ 1,004,576
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents	264,705	294,256
Marketable securities	743,624	1,004,576
Derivative assets	109	220
Contingent consideration	37,436	3,350
Derivative liabilities	146	369
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents	264,705	294,256
Marketable securities	743,624	1,004,576
Derivative assets	109	220
Contingent consideration	37,436	3,350
Derivative liabilities	$ 146	$ 369

Schedule of Available for Sale

Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 745,498	$ 1,000,625
Available-for-sale marketable securities, Unrealized Gain	2,145	4,818
Available-for-sale marketable securities, Unrealized (Loss)	(4,019)	(867)
Available-for-sale marketable securities, Fair Market Value	743,624	1,004,576
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	601,660	583,076
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	421,060	402,197
Available-for-sale marketable securities, Unrealized Gain	65	362
Available-for-sale marketable securities, Unrealized (Loss)	(1,167)	(405)
Available-for-sale marketable securities, Fair Market Value	419,958	402,154
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	379,434	317,771
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	84,032	258,452
Available-for-sale marketable securities, Unrealized Gain	42	135
Available-for-sale marketable securities, Unrealized (Loss)	(122)	(85)
Available-for-sale marketable securities, Fair Market Value	83,952	258,502
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	55,120	104,642
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	163,297	139,374
Available-for-sale marketable securities, Unrealized Gain	902	2,414
Available-for-sale marketable securities, Unrealized (Loss)	(2,565)	(321)
Available-for-sale marketable securities, Fair Market Value	161,634	141,467
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	145,373	96,998
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	20,298	140,616
Available-for-sale marketable securities, Unrealized Gain	11	26
Available-for-sale marketable securities, Unrealized (Loss)	(1)	(4)
Available-for-sale marketable securities, Fair Market Value	20,308	140,638
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	8,646	41,747
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	43,391	49,048
Available-for-sale marketable securities, Unrealized Gain	6	11
Available-for-sale marketable securities, Unrealized (Loss)	(3)	(23)
Available-for-sale marketable securities, Fair Market Value	43,394	49,036
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	10,527	20,684
Equity And Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	12,996	10,492
Available-for-sale marketable securities, Unrealized Gain	1,119	1,870
Available-for-sale marketable securities, Unrealized (Loss)	(161)	(29)
Available-for-sale marketable securities, Fair Market Value	13,954	12,333
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	2,560	1,234
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	424	446
Available-for-sale marketable securities, Fair Market Value	$ 424	$ 446

Schedule of Reported Available

Schedule of Reported Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 745,498	$ 1,000,625
Available-for-sale marketable securities, Unrealized Gain	2,145	4,818
Available-for-sale marketable securities, Unrealized (Loss)	(4,019)	(867)
Available-for-sale marketable securities, Fair Market Value	743,624	1,004,576
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	601,660	583,076
Marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	478,306	533,833
Available-for-sale marketable securities, Unrealized Gain	38	99
Available-for-sale marketable securities, Unrealized (Loss)	(648)	(145)
Available-for-sale marketable securities, Fair Market Value	477,696	533,787
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	374,785	240,234
Long-term marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	267,192	466,792
Available-for-sale marketable securities, Unrealized Gain	2,107	4,719
Available-for-sale marketable securities, Unrealized (Loss)	(3,371)	(722)
Available-for-sale marketable securities, Fair Market Value	265,928	470,789
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 226,875	$ 342,842

Contractual Maturities of Inves

Contractual Maturities of Investments Held (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Schedule of Available-for-sale Securities
Due within one year, cost	$ 478,306
Due after 1 year through 5 years, cost	209,822
Due after 5 years through 10 years, cost	5,183
Due after 10 years, cost	39,191
Total, cost	732,502
Due within one year, fair value	477,696
Due after 1 year through 5 years, fair value	209,314
Due after 5 years through 10 years, fair value	5,179
Due after 10 years, fair value	37,481
Total, fair value	$ 729,670

Assets Measured at Fair Value o

Assets Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets, impairment loss
Goodwill, impairment loss	$ 98,897	[1],[2],[3]		$ 98,897	$ 0
Definite lived intangible assets, impairment loss			$ 98,200
Fair Value, Measurements, Nonrecurring
Assets
Goodwill, fair value	273,438			273,438
Definite lived intangible assets, fair value	158,237			158,237
Long-lived assets held and used, fair value	10,189			10,189
Total	441,864			441,864
Assets, impairment loss
Goodwill, impairment loss				98,897
Definite lived intangible assets, impairment loss				0
Long-lived assets held and used, impairment loss				0
Asset Impairment Charges, Total				98,897
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Assets
Long-lived assets held and used, fair value	10,189			10,189
Total	10,189			10,189
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3)
Assets
Goodwill, fair value	273,438			273,438
Definite lived intangible assets, fair value	158,237			158,237
Total	$ 431,675			$ 431,675
[1]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[2]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[3]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

Schedule of Notional Amount of

Schedule of Notional Amount of Derivatives (Detail) - Foreign Currency Forward Contracts - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	$ (29.7)	$ 10
Buy Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(71.9)	(31.5)
Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	42.2	41.5
Japanese Yen
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(51.9)	19.7
Japanese Yen | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(51.9)
Japanese Yen | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts		19.7
British Pound Sterling
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(9.5)	11.7
British Pound Sterling | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(9.5)
British Pound Sterling | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts		11.7
Korean Won
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(5.5)	4.4
Korean Won | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(5.5)
Korean Won | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts		4.4
Taiwan Dollar
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(5)	4.8
Taiwan Dollar | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	(5)	(0.9)
Taiwan Dollar | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts		5.7
Euro
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	27.2	(30.6)
Euro | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts		$ (30.6)
Euro | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	27.2
Singapore Dollar
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	15
Singapore Dollar | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Notional amounts	$ 15

Schedule of Derivative Instrume

Schedule of Derivative Instruments in Statement of Financial Position at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net	$ (37)	$ (149)
Not Designated as Hedging Instrument | Foreign Currency Forward Contracts | Prepayments
Derivatives, Fair Value [Line Items]
Derivative assets	109	220
Not Designated as Hedging Instrument | Foreign Currency Forward Contracts | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (146)	$ (369)

Schedule of Effect of Derivativ

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts derivatives not designated as hedging instruments, Gains (Losses) Recognized in Statement of Operations	$ 3,047	$ 237	$ (5,933)
Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange contracts derivatives not designated as hedging instruments, Gains (Losses) Recognized in Statement of Operations	$ 3,047	$ 237	$ (5,933)

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Apr. 27, 2015	Mar. 13, 2014	Apr. 01, 2009	Mar. 31, 2009	Mar. 30, 2014	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument
Term of loan, years	5 years			5 years
Pledge percentage of capital stock	65.00%
Borrowings from local bank				$ 10,000,000
Debt instrument, interest rate, stated percentage				0.80%
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
Payments of long-term debt								$ 190,972,000	$ 2,534,000
Common stock shares were issued for warrants exercised								21,200,000
Strike price per share of warrant								$ 7.6348
Maximum
Debt Instrument
Aggregate principal amount	$ 150,000,000
Commitment fee percentage of unused portion of credit facility	0.35%
Minimum
Debt Instrument
Commitment fee percentage of unused portion of credit facility	0.125%
Base Rate | Maximum
Debt Instrument
Debt instrument, basis spread on variable rate	1.00%
Base Rate | Minimum
Debt Instrument
Debt instrument, basis spread on variable rate	0.00%
London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument
Debt instrument, basis spread on variable rate	2.00%
London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument
Debt instrument, basis spread on variable rate	1.00%
Revolving Credit Facility
Debt Instrument
Financing cost							$ 2,300,000
Financing cost, amortization term							5 years
Revolving Credit Facility | Maximum
Debt Instrument
Credit facility, borrowing capacity	$ 350,000,000
4.50% Convertible Senior Notes Due March 15, 2014
Debt Instrument
Aggregate principal amount			$ 190,000,000	$ 175,000,000
Debt instrument, interest rate, stated percentage				4.50%
Additional aggregate principal amount			$ 15,000,000	$ 1,000
Senior notes maturity date			Mar. 15, 2014	Mar. 15, 2014
Conversion rate in number of shares				182.65			131.95
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							$ 190,000,000
Stock issued in conversion of notes							25,100,000
Stock received and retired		25,100,000

Interest Expense on Convertible

Interest Expense on Convertible Senior Notes (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2014USD ($)
Debt Instrument
Contractual interest expense on the coupon	$ 1,757
Amortization of the discount component and debt issue fees recognized as interest expense	4,493
Total interest expense on the convertible debt	$ 6,250

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income (Loss) Balances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 4,689		$ 4,000
Other comprehensive income (loss) before reclassifications, net of tax	(11,834)	$ 2,417
Amounts reclassified from accumulated other comprehensive income, net of tax	(999)	(1,728)	(723)
Other comprehensive (loss) income	(12,833)	689	(1,820)
Ending balance	(8,144)	4,689
Foreign currency translation reclassification adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	(8,759)
Other comprehensive (loss) income	(8,759)
Ending balance	(8,759)
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	2,365		1,381
Other comprehensive income (loss) before reclassifications, net of tax	(3,075)	2,417
Amounts reclassified from accumulated other comprehensive income, net of tax	(704)	(1,433)
Other comprehensive (loss) income	(3,779)	984
Ending balance	(1,414)	2,365
Retirement Plans Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	2,324		$ 2,619
Amounts reclassified from accumulated other comprehensive income, net of tax	(295)	(295)
Other comprehensive (loss) income	(295)	(295)
Ending balance	$ 2,029	$ 2,324

Changes in Accumulated Other 75

Changes in Accumulated Other Comprehensive Income (Loss) Balances (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income before reclassifications, tax	$ (1,667)	$ 1,449	$ (216)
Other comprehensive income before reclassifications, tax	0
Amounts reclassified from accumulated other comprehensive income, tax	(390)	(645)	(257)
Amounts reclassified from accumulated other comprehensive income, tax	(169)	(169)	(159)
Foreign currency translation adjustments, tax	0
Unrealized gains (losses) on marketable securities, tax	(459)	1,598	794
Retirement plans prior service benefit, tax	(622)	(453)	$ (284)
Foreign currency translation reclassification adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), tax	0
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), tax	(2,057)	804
Retirement Plans Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), tax	$ (169)	$ (169)

Reclassification Out of Accumul

Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains, net of tax		$ 704	$ 1,433	$ 447
Prior service benefit	[1]	295	295	276
Total reclassifications		999	1,728	723
Interest Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains, net of tax		$ 704	$ 1,433	$ 447
[1]	The amortization of prior service benefit is included in the computation of net periodic pension cost and postretirement benefit; see Note M: "Retirement Plans."

Reclassification Out of Accum77

Reclassification Out of Accumulated Other Comprehensive Income to Statement of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains, tax	$ (390)	$ (645)	$ (257)
Prior service benefit, tax	(169)	(169)	(159)
Total reclassifications, tax	$ 559	$ 814	$ 416

Goodwill and Intangible Asset78

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands

Jun. 11, 2015

Oct. 31, 2014

Dec. 31, 2015

[4],[5]

Oct. 04, 2015

[6]

Jul. 05, 2015

[7]

Apr. 05, 2015

Dec. 31, 2014

Sep. 28, 2014

[1],[8]

Jun. 29, 2014

[1]

Mar. 30, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Goodwill and Intangible Assets Disclosure [Line Items]

Goodwill impairment charge

$ 98,897

[1],[2],[3]

$ 98,897

$ 0

Fully amortized intangible assets wrote off

$ 98,200

Acquired intangible assets amortization

$ 19,911

$ 20,053

$ 15,258

$ 13,808

15,957

[1],[2],[3]

$ 18,271

$ 18,271

$ 18,271

69,031

70,771

$ 72,447

Avionics Interface Technologies, LLC

Goodwill and Intangible Assets Disclosure [Line Items]

Intangible assets

$ 9,080

$ 9,080

Universal Robots

Goodwill and Intangible Assets Disclosure [Line Items]

Intangible assets

$ 121,590

$ 121,590

System Test

Goodwill and Intangible Assets Disclosure [Line Items]

Goodwill impairment charge

$ 0

[1]

Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.

[2]

In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.

[3]

In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[4]

In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[5]

Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[6]

Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[7]

Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[8]

Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

Changes in Carrying Amount of G

Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Jun. 11, 2015	Oct. 31, 2014	Oct. 25, 2013
Goodwill [Line Items]
Goodwill	$ 781,058	$ 770,515	$ 996,033
Accumulated impairment losses	(507,620)	(408,723)	(507,620)
Goodwill	273,438		488,413
Foreign currency translation adjustment	(6,153)
ZTEC Instruments, Inc.
Goodwill [Line Items]
Goodwill						$ 12,520
Adjustment		27
Avionics Interface Technologies, LLC
Goodwill [Line Items]
Goodwill					$ 10,516
Acquisition		10,516
Universal Robots
Goodwill [Line Items]
Goodwill				$ 221,128
Acquisition	221,128
Semiconductor Test
Goodwill [Line Items]
Goodwill	361,819	361,792	361,819
Accumulated impairment losses	(98,897)		(98,897)
Goodwill			262,922
Semiconductor Test | ZTEC Instruments, Inc.
Goodwill [Line Items]
Adjustment		27
Industrial Automation
Goodwill [Line Items]
Goodwill			214,975
Goodwill			214,975
Foreign currency translation adjustment	(6,153)
Industrial Automation | Universal Robots
Goodwill [Line Items]
Acquisition	221,128
System Test
Goodwill [Line Items]
Goodwill	158,699	148,183	158,699
Accumulated impairment losses	(148,183)	(148,183)	(148,183)
Goodwill			10,516
System Test | Avionics Interface Technologies, LLC
Goodwill [Line Items]
Acquisition		10,516
Wireless Test
Goodwill [Line Items]
Goodwill	260,540	260,540	260,540
Accumulated impairment losses	$ (260,540)	$ (260,540)	$ (260,540)

Schedule of Amortizable Intangi

Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 543,004	$ 523,052
Accumulated Amortization	303,173	332,452
Net Carrying Amount	$ 239,831	$ 190,600
Weighted Average Useful Life, years	6 years 8 months 12 days	6 years 9 months 18 days
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 379,778	$ 345,513
Accumulated Amortization	220,306	224,059
Net Carrying Amount	$ 159,472	$ 121,454
Weighted Average Useful Life, years	6 years	6 years 2 months 12 days
Customer Relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 110,340	$ 146,635
Accumulated Amortization	63,718	93,998
Net Carrying Amount	$ 46,622	$ 52,637
Weighted Average Useful Life, years	7 years 10 months 24 days	7 years 8 months 12 days
Trademarks and tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 52,396	$ 30,414
Accumulated Amortization	18,879	14,205
Net Carrying Amount	$ 33,517	$ 16,209
Weighted Average Useful Life, years	9 years 6 months	9 years
Non-compete agreements
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 320	$ 320
Accumulated Amortization	100	20
Net Carrying Amount	$ 220	$ 300
Weighted Average Useful Life, years	4 years	4 years
Customer backlog
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 170	$ 170
Accumulated Amortization	$ 170	$ 170
Weighted Average Useful Life, years	3 months 18 days	3 months 18 days

Schedule of Estimated Intangibl

Schedule of Estimated Intangible Asset Amortization Expense (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Finite-Lived Intangible Assets
2,016	$ 79,874
2,017	71,133
2,018	44,464
2,019	23,611
2,020	9,990
Thereafter	$ 10,759

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments	$ 237
Purchase commitments less than one year	230.3
Rental expense under lease commitments	$ 15.9	$ 16	$ 16.5
Warranty period	1 year
Product warranty accrual	$ 6.9	8.9
Revenue deferrals related to extended warranties	$ 46.5	$ 43.3

Non Cancelable Operating Lease

Non Cancelable Operating Lease Commitments (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Commitments and Contingencies Disclosure [Line Items]
2,016	$ 15,665
2,017	11,778
2,018	9,559
2,019	8,487
2,020	7,222
Beyond 2,021	16,009
Total	$ 68,720

Computation of Basic and Dilute

Computation of Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended														12 Months Ended
		Dec. 31, 2015	[1],[2]	Oct. 04, 2015	[3]	Jul. 05, 2015	[4]	Apr. 05, 2015	Dec. 31, 2014	[5],[6],[7]	Sep. 28, 2014	[5],[8]	Jun. 29, 2014	[5]	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income Loss Per Common Share
Net income for basic and diluted net income per share		$ (641)		$ 71,453		$ 102,879		$ 32,787	$ (103,811)		$ 82,949		$ 101,205		$ 929	$ 206,477	$ 81,272	$ 164,947
Weighted average common shares-basic																211,544	202,908	190,772
Incremental shares from assumed conversion of convertible notes	[9]																5,013	23,341
Convertible note hedge warrant shares	[10]																12,562	18,795
Employee stock purchase rights																41	31	36
Dilutive potential common shares																1,777	19,642	44,827
Weighted average common shares-diluted																213,321	222,550	235,599
Net income per common share-basic		$ 0		$ 0.34		$ 0.48		$ 0.15	$ (0.48)		$ 0.40		$ 0.52		$ 0	$ 0.98	$ 0.40	$ 0.86
Net income per common share-diluted		$ 0		$ 0.34		$ 0.48		$ 0.15	$ (0.48)		$ 0.38		$ 0.47		$ 0	$ 0.97	$ 0.37	$ 0.70
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements																1,130	1,092	1,127
Stock Options
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements																606	944	1,528
[1]	In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[2]	Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[3]	Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[4]	Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[5]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[6]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[7]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[8]	Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[9]	Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $5.48, 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.
[10]	Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $7.67, multiplied by 34.7 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne's call option on its common stock (convertible note hedge transaction) was excluded from the calculation of diluted shares because the effect was anti-dilutive. See Note G: "Debt" regarding the convertible note hedge transaction.

Computation of Basic and Dilu85

Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail) shares in Millions	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Convertible Notes
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 5.48
Shares that would be issued upon conversion | shares	34.7
Convertible Notes Hedge Warrant
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 7.67
Shares that would be issued upon conversion | shares	34.7

Net Income Per Common Share - A

Net Income Per Common Share - Additional Information (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income Loss Per Common Share
Exercise of stock options	0.2	0.3	0.4

Restructuring and Other - Addit

Restructuring and Other - Additional Information (Detail) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2015USD ($)	Oct. 04, 2015USD ($)	Jul. 05, 2015USD ($)	Sep. 28, 2014USD ($)	Dec. 31, 2015USD ($)Employee	Dec. 31, 2014USD ($)Employee	Dec. 31, 2013USD ($)Employee
Restructuring Cost and Reserve
Other restructuring charges					$ 3,600
Contingent consideration adjustment					2,489	$ (630)
Severance benefit and charges					400
System Test and Semiconductor Test
Restructuring Cost and Reserve
Severance benefit and charges					$ 1,500		$ 1,900
Reduction in employees headcount | Employee					23		48
Corporate And Eliminations
Restructuring Cost and Reserve
Change in estimated exit costs related to leased facility							$ (400)
Semiconductor Test and Wireless Test
Restructuring Cost and Reserve
Severance benefit and charges						$ 1,600
Reduction in employees headcount | Employee						43
ZTEC Instruments, Inc.
Restructuring Cost and Reserve
Contingent consideration adjustment			$ (1,600)	$ (630)	$ (1,600)	$ (630)
Avionics Interface Technologies, LLC
Restructuring Cost and Reserve
Contingent consideration adjustment	$ (300)	$ (1,000)			(1,250)
Acquisition related costs						$ 372
Universal Robots
Restructuring Cost and Reserve
Contingent consideration adjustment	$ 5,339				5,339
Acquisition related costs					1,104
ZTEC Corporation and Avionics Interface Technologies LLC
Restructuring Cost and Reserve
Contingent consideration adjustment					$ (2,900)

Schedule of Defined Benefit Pen

Schedule of Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligation (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure
Actuarial (gain) loss	$ (17,732)	$ (46,564)	$ (17,732)	$ (46,564)	$ 10,340
Ending Balance	326,600		326,600
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year			367,619	293,912
Service cost			2,462	2,218	2,393
Interest cost			13,142	12,875	11,318
Actuarial (gain) loss			(13,221)	72,596
Benefits paid			(18,885)	(13,982)
Projected benefit obligation, End of year	351,117	367,619	351,117	367,619	293,912
Beginning Balance			316,072	256,373
Company contributions			10,517	31,753
Actual return on plan assets			(9,300)	41,928
Benefits paid			(18,885)	(13,982)
Ending Balance	298,404	316,072	298,404	316,072	256,373
Funded status	(52,713)	(51,547)	(52,713)	(51,547)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year			58,210	52,182
Service cost			1,006	897	1,034
Interest cost			1,444	1,837	1,948
Actuarial (gain) loss			7,498	8,975
Benefits paid			(859)	(1,265)
Curtailment			(634)
Plan participants' contributions			64	88
Non-U.S. currency movement			(4,439)	(4,504)
Projected benefit obligation, End of year	62,290	58,210	62,290	58,210	52,182
Beginning Balance			29,511	25,756
Company contributions			808	1,168
Plan participants' contributions			64	88
Actual return on plan assets			(136)	5,192
Benefits paid			(859)	(1,265)
Admin expenses paid			(43)
Non-U.S. currency movement			(1,204)	(1,428)
Ending Balance	28,141	29,511	28,141	29,511	25,756
Funded status	(34,149)	(28,699)	(34,149)	(28,699)
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year			7,162	9,019
Service cost			48	59	75
Interest cost			237	335	342
Actuarial (gain) loss			(648)	(1,255)
Benefits paid			(769)	(996)
Projected benefit obligation, End of year	6,030	7,162	6,030	7,162	$ 9,019
Company contributions			769	996
Benefits paid			(769)	(996)
Funded status	$ (6,030)	$ (7,162)	$ (6,030)	$ (7,162)

Schedule of Amounts Recorded wi

Schedule of Amounts Recorded within Statement of Financial Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Retirement plans assets	$ 636	$ 3,090
Accrued employees' compensation and withholdings	(2,564)	(2,492)
Retirement plans liabilities	(50,785)	(52,145)
Funded status	(52,713)	(51,547)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Retirement plans assets		9,806
Accrued employees' compensation and withholdings	(695)	(906)
Retirement plans liabilities	(33,454)	(37,599)
Funded status	(34,149)	(28,699)
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Accrued employees' compensation and withholdings	(692)	(780)
Retirement plans liabilities	(5,338)	(6,382)
Funded status	$ (6,030)	$ (7,162)

Schedule of Amounts Recognized

Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure
Deferred taxes	$ (10,597)	$ (12,018)	$ (12,192)
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Prior service cost, before tax	224	358
Deferred taxes	479	429
Total recognized in other comprehensive income, net of tax	703	787
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Prior service cost, before tax	(1,632)	(2,230)
Deferred taxes	(1,100)	(882)
Total recognized in other comprehensive income, net of tax	$ (2,732)	$ (3,112)

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure
Accumulated other comprehensive income (loss), prior service cost expected to be recognized in 2016	$ 100
Fair value of pension plans assets totaled	$ 326,600
United States Plans
Defined Benefit Plan Disclosure
Percentage of expected return on plan assets assumption	4.80%
Discount rate utilized to determine future pension obligations	4.00%	3.70%
Fair value of pension plans assets totaled	$ 298,400
Contribution to defined benefit pension plans	8,000	$ 30,000
U.K. Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Fair value of pension plans assets totaled	27,100
Taiwan Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Fair value of pension plans assets totaled	1,000
U.S. Supplemental Executive Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans	2,500	1,800
Contribution to defined benefit pension plans in 2016	2,600
Non-United States Subsidiaries
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans	800	$ 1,200
Contribution to defined benefit pension plans in 2016	800
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Accumulated other comprehensive income (loss), prior service cost expected to be recognized in 2016	$ (600)
Discount rate utilized to determine future pension obligations	3.90%	3.50%	4.10%
Contribution to defined benefit pension plans	$ 769	$ 996
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Accumulated benefit obligation for defined benefit pension plans	$ 340,100	$ 357,000
Percentage of expected return on plan assets assumption	4.80%	5.00%	5.00%
Discount rate utilized to determine future pension obligations	4.00%	3.70%
Fair value of pension plans assets totaled	$ 298,404	$ 316,072	$ 256,373
Contribution to defined benefit pension plans	10,517	31,753
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Accumulated benefit obligation for defined benefit pension plans	$ 56,600	$ 49,800
Percentage of expected return on plan assets assumption	2.60%	3.40%	3.70%
Discount rate utilized to determine future pension obligations	2.30%	2.60%
Fair value of pension plans assets totaled	$ 28,141	$ 29,511	$ 25,756
Contribution to defined benefit pension plans	$ 808	$ 1,168

Schedule of Pension Plans with

Schedule of Pension Plans with Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation	$ 53.3	$ 54.6
Accumulated benefit obligation	47.3	48.5
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation	35.2	39.5
Accumulated benefit obligation	29.5	32.7
Fair value of plan assets	$ 1	$ 1

Schedule of Net Periodic Pensio

Schedule of Net Periodic Pension and Postretirement (income) Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	$ 2,462	$ 2,218	$ 2,393
Interest cost	13,142	12,875	11,318
Expected return on plan assets	(14,517)	(12,500)	(13,632)
Amortization of prior service cost	134	135	164
Net actuarial loss (gain)	10,596	43,168	(7,063)
Total net periodic pension cost (income)	11,817	45,896	(6,820)
Prior service cost	(134)	(135)	(164)
Total recognized in other comprehensive income	(134)	(135)	(164)
Total recognized in net periodic pension cost (income) and other comprehensive income	11,683	45,761	(6,984)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	1,006	897	1,034
Interest cost	1,444	1,837	1,948
Expected return on plan assets	(781)	(868)	(959)
Net actuarial loss (gain)	8,415	4,651	(1,252)
Curtailment	(634)
Total net periodic pension cost (income)	9,450	6,517	771
Total recognized in net periodic pension cost (income) and other comprehensive income	9,450	6,517	771
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Service cost	48	59	75
Interest cost	237	335	342
Amortization of prior service cost	(598)	(598)	(598)
Net actuarial loss (gain)	(648)	(1,255)	(2,025)
Total net periodic pension cost (income)	(961)	(1,459)	(2,206)
Prior service cost	598	598	598
Total recognized in other comprehensive income	598	598	598
Total recognized in net periodic pension cost (income) and other comprehensive income	$ (363)	$ (861)	$ (1,608)

Schedule of Weighted Average -

Schedule of Weighted Average - Assumptions to Determine Net Periodic Pension Cost (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	3.70%	4.50%	3.60%
Expected return on plan assets	4.80%	5.00%	5.00%
Salary progression rate	2.90%	3.00%	3.00%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	2.60%	3.80%	3.70%
Expected return on plan assets	2.60%	3.40%	3.70%
Salary progression rate	3.20%	3.50%	3.50%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	3.50%	4.10%	3.10%
Initial health care cost trend rate	7.50%	8.00%	8.50%
Ultimate health care cost trend rate	5.00%	5.00%	5.00%
Year in which ultimate health care cost trend rate is reached	2,022	2,020	2,020

Schedule of Weighted Average As

Schedule of Weighted Average Assumptions to Determine Pension Obligations (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	4.00%	3.70%
Salary progression rate	2.70%	2.90%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	2.30%	2.60%
Salary progression rate	3.20%	3.20%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	3.90%	3.50%	4.10%
Initial medical trend	7.50%	7.50%	8.00%
Ultimate health care trend	5.00%	5.00%	5.00%
Medical cost trend rate decrease to ultimate rate in year	2,023	2,022	2,020

Schedule of Weighted Average Pe

Schedule of Weighted Average Pension Assets Allocations by Category (Detail)	Dec. 31, 2015	Dec. 31, 2014
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	100.00%	100.00%
United States Pension Plans, Defined Benefit | Fixed income securities
Defined Benefit Plan Disclosure
Total	88.60%	83.30%
United States Pension Plans, Defined Benefit | Equity securities
Defined Benefit Plan Disclosure
Total	9.80%	15.40%
United States Pension Plans, Defined Benefit | Other than Securities Investment
Defined Benefit Plan Disclosure
Total	1.60%	1.30%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	100.00%	100.00%
Foreign Pension Plans, Defined Benefit | Fixed income securities
Defined Benefit Plan Disclosure
Total		77.30%
Foreign Pension Plans, Defined Benefit | Equity securities
Defined Benefit Plan Disclosure
Total		19.00%
Foreign Pension Plans, Defined Benefit | Other than Securities Investment
Defined Benefit Plan Disclosure
Total	100.00%	3.70%

Schedule of Target Assets Alloc

Schedule of Target Assets Allocation (Detail)	12 Months Ended
	Dec. 31, 2015
Barclays Corporate A or Better Index | U.S. corporate fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	76.00%
Msci World Minimum Volatility Index | Global equity Securities
Defined Benefit Plan Disclosure
Target assets allocation percentage	10.00%
Barclays U.S. Long Government/Credit Bond Index | U.S. government fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	8.00%
Barclays Corporate High Yield Issuer Cap Index | High yield fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	5.00%
Citi Group Three Month Treasury Bill Index | Cash
Defined Benefit Plan Disclosure
Target assets allocation percentage	1.00%

Schedule of Fair Value of Pensi

Schedule of Fair Value of Pensions Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure
Total	$ 326,600
Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	29,392	$ 2,990	$ 2,985
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	298,404	316,072	256,373
United States Pension Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	1,773	1,098
United States Pension Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	293,649	311,984
United States Pension Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	2,982	2,990
United States Pension Plans, Defined Benefit | Corporate Debt Securities
Defined Benefit Plan Disclosure
Total	240,695	193,741
United States Pension Plans, Defined Benefit | Corporate Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	240,695	193,741
United States Pension Plans, Defined Benefit | US Government Debt Securities
Defined Benefit Plan Disclosure
Total	23,761	65,830
United States Pension Plans, Defined Benefit | US Government Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	23,761	65,830
United States Pension Plans, Defined Benefit | Global equity Securities
Defined Benefit Plan Disclosure
Total	29,193
United States Pension Plans, Defined Benefit | Global equity Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	29,193
United States Pension Plans, Defined Benefit | Group Annuity Insurance Contracts
Defined Benefit Plan Disclosure
Total	2,982	2,990
United States Pension Plans, Defined Benefit | Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	2,982	2,990
United States Pension Plans, Defined Benefit | Other
Defined Benefit Plan Disclosure
Total		65
United States Pension Plans, Defined Benefit | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total		65
United States Pension Plans, Defined Benefit | Cash and Cash Equivalents
Defined Benefit Plan Disclosure
Total	1,773	1,098
United States Pension Plans, Defined Benefit | Cash and Cash Equivalents | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	1,773	1,098
United States Pension Plans, Defined Benefit | Asset-backed Securities
Defined Benefit Plan Disclosure
Total		3,747
United States Pension Plans, Defined Benefit | Asset-backed Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total		3,747
United States Pension Plans, Defined Benefit | U.S. Equity (Large Cap)
Defined Benefit Plan Disclosure
Total		33,970
United States Pension Plans, Defined Benefit | U.S. Equity (Large Cap) | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total		33,970
United States Pension Plans, Defined Benefit | International Equity
Defined Benefit Plan Disclosure
Total		14,631
United States Pension Plans, Defined Benefit | International Equity | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total		14,631
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	28,141	29,511	$ 25,756
Foreign Pension Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	702	133
Foreign Pension Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	1,029	29,378
Foreign Pension Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	26,410
Foreign Pension Plans, Defined Benefit | Group Annuity Insurance Contracts
Defined Benefit Plan Disclosure
Total	26,410
Foreign Pension Plans, Defined Benefit | Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	26,410
Foreign Pension Plans, Defined Benefit | Other
Defined Benefit Plan Disclosure
Total	1,029	957
Foreign Pension Plans, Defined Benefit | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	1,029	957
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents
Defined Benefit Plan Disclosure
Total	702	133
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	$ 702	133
Foreign Pension Plans, Defined Benefit | U.K. Government Securities
Defined Benefit Plan Disclosure
Total		22,811
Foreign Pension Plans, Defined Benefit | U.K. Government Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total		22,811
Foreign Pension Plans, Defined Benefit | International Equity
Defined Benefit Plan Disclosure
Total		5,610
Foreign Pension Plans, Defined Benefit | International Equity | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total		$ 5,610

Schedule of defined benefit pla

Schedule of defined benefit plans disclosures (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure
Ending Balance	$ 326,600
Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Beginning Balance	2,990	$ 2,985
Purchases of group annuity insurance contracts	27,313
Interest and market value adjustments	(825)	152
Benefits paid	(67)	(125)
Other	(19)	(22)
Ending Balance	$ 29,392	$ 2,990

Schedule of Expected Future Ben

Schedule of Expected Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2015USD ($)
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
2,016	$ 19,696
2,017	18,346
2,018	18,836
2,019	19,453
2,020	20,129
2021-2025	109,860
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
2,016	1,062
2,017	1,032
2,018	1,021
2,019	1,477
2,020	1,266
2021-2025	8,561
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
2,016	692
2,017	587
2,018	553
2,019	492
2,020	410
2021-2025	$ 1,654

Schedule of One Percent Point C

Schedule of One Percent Point Change in assumed Health Care Cost Trends Rate (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure
Effect of one percentage point increase on total service and interest cost components	$ 3
Effect of one percentage point increase on postretirement benefit obligations	59
Effect of one percentage point decrease on total service and interest cost components	(2)
Effect of one percentage point decrease on postretirement benefit obligations	$ (56)

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($)	May. 21, 2013	Jan. 31, 2016	Jul. 31, 2015	Jan. 31, 2015	Jul. 31, 2014	Jan. 31, 2014	Jul. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of common stock price paid								85.00%
Stock options term								7 years
Restricted stock unit awards granted								1,681,000	1,870,000	2,110,000
Weighted average grant date fair value of restricted stock units granted								$ 17.36	$ 18.41	$ 16.62
Stock options granted								132,000	89,000	213,000
Weighted average grant date fair value								$ 4.43	$ 5.49	$ 6.09
Total unrecognized expense related to non-vested restricted stock unit awards and stock options								$ 44,900,000
Unrecognized expense related to non-vested restricted stock unit awards and stock options expected to be recognized over weighted average period, in years								2 years 3 months 18 days
Stock based compensation expense						$ 6,600,000		$ 30,451,000	$ 40,307,000	$ 36,612,000
Maximum percent of shares allowed to purchase								10.00%
Fair market value								$ 25,000
Maximum number of shares allowed to purchase								6,000
Common stock issued to employees			500,000	500,000	500,000	400,000	400,000
Value of common stock issued to employees per share			$ 16.40	$ 16.82	$ 16.66	$ 14.98	$ 14.94
Number of shares available for grant								10,914,000	12,443,000	14,213,000	6,414,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of common stock price paid								100.00%
Period of stock granted to employees and executive officers vest in equal annual installments								4 years
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted								1,681,000	1,870,000	2,110,000
Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal annual installments								4 years
Restricted Stock Units | Director
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal annual installments								1 year
Percentage of awards vesting on the first anniversary of grant date								100.00%
TSR Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Total shareholder return performance measurement period						3 years
Minimum age of retirement to be eligible for PRSUs						60 years
Minimum years of service for retirement to be eligible for PRSUs						10 years
Restricted stock unit awards granted								200,000	100,000
Weighted average grant date fair value of restricted stock units granted								$ 18.21	$ 22.06
Estimated annual dividend amount per share								0.24	0.24
Stock price								$ 18.10	$ 19.16
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved						200.00%
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved						0.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares available for grant								4,900,000
2006 Equity and Cash Compensation Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award
Employee Stock Purchase Plan to increase the number of shares issuable	10,000,000
Aggregate number of shares issuable	32,000,000
1996 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Employee Stock Purchase Plan to increase the number of shares issuable	5,000,000
Aggregate number of shares issuable	30,400,000
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued to employees		500,000
Value of common stock issued to employees per share		$ 17.57

Schedule of Estimated Fair Valu

Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail) - TSR Performance-Based Restricted Stock Units	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rate	0.77%	0.75%
Teradyne volatility-historical	28.20%	36.10%
Philadelphia Semiconductor Index volatility-historical	19.70%	24.60%
Dividend yield	1.33%	1.25%

Schedule of Estimated Fair V104

Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail) - Stock Options	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Expected life (years)	4 years	4 years	4 years
Risk-free interest rate	1.10%	1.20%	0.60%
Volatility-historical	33.40%	38.80%	46.80%
Dividend yield	1.33%	1.25%	0.00%

Schedule of Stock Compensation

Schedule of Stock Compensation Plan Activity (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Awarded	1,681	1,870	2,110
Forfeited	(284)	(189)	(122)
Outstanding at January 1	1,507	2,706	3,841
Granted	132	89	213
Exercised	(518)	(1,248)	(1,220)
Forfeited		(38)	(104)
Expired		(2)	(24)
Outstanding at December 31	1,121	1,507	2,706
Vested and expected to vest at December 31	1,121	1,507	2,694
Exercisable at December 31	779	1,089	1,814
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Non-vested at January 1	4,352	4,636	4,970
Awarded	1,681	1,870	2,110
Vested	(1,679)	(1,965)	(2,322)
Forfeited	(284)	(189)	(122)
Non-vested at December 31	4,070	4,352	4,636

Schedule of Share Based Compens

Schedule of Share Based Compensation Total Shares Available (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Available for grant at January 1	12,443	14,213	6,414
Options granted	(132)	(89)	(213)
Restricted stock units awarded	(1,681)	(1,870)	(2,110)
Restricted stock units forfeited	284	189	122
Additional shares reserved			10,000
Available for grant at December 31	10,914	12,443	14,213

Schedule of Weighted-Average Re

Schedule of Weighted-Average Restricted Stock Unit Award Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Non-vested at January 1	$ 17.24	$ 15.60	$ 12.72
Awarded	17.36	18.41	16.62
Vested	16.85	14.38	10.40
Forfeited	17.08	16.97	15.48
Non-vested at December 31	$ 17.46	$ 17.24	$ 15.60

Schedule of Restricted Stock Un

Schedule of Restricted Stock Unit Awards Aggregate Intrinsic Value (Detail) - Restricted Stock Units - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	$ 84,129	$ 86,113	$ 81,680
Expected to vest	$ 79,611	$ 81,582	$ 77,388

Schedule of Restricted Stock109

Schedule of Restricted Stock Units Weighted Average Remaining Contractual Terms (Detail) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	1 year 1 month 2 days	1 year 1 month 10 days	1 year 1 month 21 days
Expected to vest	1 year 29 days	1 year 1 month 6 days	1 year 1 month 17 days

Schedule of Weighted Average St

Schedule of Weighted Average Stock Options Exercise Price (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding at January 1	$ 7.89	$ 6.29	$ 4.64
Options granted	18.10	19.16	16.56
Options exercised	5.49	5.34	3.28
Options forfeited	8.67	3.59	2.57
Options cancelled	3.28	2.21	8.05
Outstanding at December 31	10.21	7.89	6.29
Exercisable at December 31	$ 6.92	$ 5	$ 4.55

Schedule of Stock Option Aggreg

Schedule of Stock Option Aggregated Intrinsic Value Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Exercised	$ 7,255	$ 17,847	$ 16,848
Outstanding	11,729	17,936	30,673
Vested and expected to vest	11,729	17,936	30,512
Exercisable	$ 10,716	$ 16,101	$ 23,707

Schedule of Stock Options Weigh

Schedule of Stock Options Weighted Average Remaining Contractual Terms (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	4 years 2 months 12 days	4 years 6 months	4 years 10 months 24 days
Vested and expected to vest	4 years 2 months 12 days	4 years 6 months	4 years 10 months 24 days
Exercisable	3 years 10 months 24 days	4 years 2 months 12 days	4 years 3 months 18 days

Schedule of Significant Option

Schedule of Significant Option Groups Outstanding (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Shares | shares	1,121
Options Exercisable, Shares | shares	779
Options Outstanding, Weighted-Average Exercise Price	$ 10.21
Options Exercisable, Weighted-Average Exercise Price	$ 6.92
$1.48 - $2.67
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	4 years 6 months 29 days
Options Outstanding, Shares | shares	416
Options Exercisable, Shares | shares	416
Range Of Exercise Prices, Lower Limit	$ 1.48
Range Of Exercise Prices, Upper Limit	2.67
Options Outstanding, Weighted-Average Exercise Price	2.33
Options Exercisable, Weighted-Average Exercise Price	$ 2.33
$3.23 - $7.71
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	2 years 8 months 16 days
Options Outstanding, Shares | shares	139
Options Exercisable, Shares | shares	139
Range Of Exercise Prices, Lower Limit	$ 3.23
Range Of Exercise Prices, Upper Limit	7.71
Options Outstanding, Weighted-Average Exercise Price	4.60
Options Exercisable, Weighted-Average Exercise Price	$ 4.60
$11.37 - $16.95
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	3 years 6 months 15 days
Options Outstanding, Shares | shares	345
Options Exercisable, Shares | shares	202
Range Of Exercise Prices, Lower Limit	$ 11.37
Range Of Exercise Prices, Upper Limit	16.95
Options Outstanding, Weighted-Average Exercise Price	16.63
Options Exercisable, Weighted-Average Exercise Price	$ 16.62
$18.10 - $19.16
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	5 years 8 months 5 days
Options Outstanding, Shares | shares	221
Options Exercisable, Shares | shares	22
Range Of Exercise Prices, Lower Limit	$ 18.10
Range Of Exercise Prices, Upper Limit	19.16
Options Outstanding, Weighted-Average Exercise Price	18.53
Options Exercisable, Weighted-Average Exercise Price	$ 19.16

Stock Based Compensation (Detai

Stock Based Compensation (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 6,600	$ 30,451	$ 40,307	$ 36,612
Income tax benefit		(8,528)	(11,537)	(9,762)
Total stock-based compensation expense after income taxes		21,923	28,770	26,850
Cost Of Revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		3,065	3,675	4,338
Engineering And Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		9,362	10,146	12,452
Selling and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		$ 18,024	$ 26,486	$ 19,822

Savings Plan - Additional Infor

Savings Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Savings Plan [Line Items]
Savings plan maximum percentage of employees contribution allowable	20.00%
Percentage of employer contributions vested per year	25.00%
Maximum employment period considered for vesting of employers' contribution, in years	4 years
U.S. Qualified Pension Plan
Savings Plan [Line Items]
Maximum percentage of matching contributions made by the employer	100.00%	100.00%	100.00%
Percentage of employer match on employee contribution	4.00%	4.00%	4.00%
Savings Plan
Savings Plan [Line Items]
Amounts charged to statement of operations	$ 13.5	$ 12.8	$ 12

Schedule of Income (loss) Befor

Schedule of Income (loss) Before Income Taxes (Detail) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2015

[1],[2]

Oct. 04, 2015

[3]

Jul. 05, 2015

[4]

Apr. 05, 2015

Dec. 31, 2014

[5],[6],[7]

Sep. 28, 2014

[5],[8]

Jun. 29, 2014

[5]

Mar. 30, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Income Tax Disclosure [Line Items]

U.S.

$ 56,270

$ (151,889)

$ 79,229

Non-U.S.

196,854

247,265

122,693

Income (loss) before income taxes

$ (8,857)

$ 87,408

$ 132,136

$ 42,438

$ (124,813)

$ 100,670

$ 121,392

$ (1,873)

$ 253,124

[9],[10]

$ 95,376

[9],[10]

$ 201,922

[9],[10]

[1]

In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[2]

Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[3]

Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[4]

Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[5]

Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.

[6]

In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.

[7]

In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[8]

Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[9]

Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges and goodwill impairment charges.

[10]

Interest income, interest expense, other (income) expense, net, contingent consideration adjustments and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations.

Schedule of Provision Benefit f

Schedule of Provision Benefit for Income Taxes from Operations (Detail) - USD ($) $ in Thousands	3 Months Ended														12 Months Ended
	Dec. 31, 2015	[1],[2]	Oct. 04, 2015	[3]	Jul. 05, 2015	[4]	Apr. 05, 2015	Dec. 31, 2014	[5],[6],[7]	Sep. 28, 2014	[5],[8]	Jun. 29, 2014	[5]	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
Current, U.S. Federal															$ 16,635	$ 5,197	$ 18,051
Current, Non-U.S.															35,707	28,157	22,509
Current, State															1,429	678	(269)
Current, Total															53,771	34,032	40,291
Deferred, U.S. Federal															(574)	(20,449)	(1,692)
Deferred, Non-U.S.															(7,761)	(404)	(1,386)
Deferred, State															1,211	925	(238)
Deferred, Total															(7,124)	(19,928)	(3,316)
Total provision for income taxes:	$ (8,216)		$ 15,955		$ 29,257		$ 9,651	$ (21,002)		$ 17,721		$ 20,187		$ (2,802)	$ 46,647	$ 14,104	$ 36,975
[1]	In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[2]	Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[3]	Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[4]	Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[5]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[6]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[7]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[8]	Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended														12 Months Ended
	Dec. 31, 2015		Oct. 04, 2015	[3]	Jul. 05, 2015	[4]	Apr. 05, 2015	Dec. 31, 2014		Sep. 28, 2014	[5],[8]	Jun. 29, 2014	[5]	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Income tax expense (benefit) from operations, total	$ (8,216,000)	[1],[2]	$ 15,955,000		$ 29,257,000		$ 9,651,000	$ (21,002,000)	[5],[6],[7]	$ 17,721,000		$ 20,187,000		$ (2,802,000)	$ 46,647,000	$ 14,104,000	$ 36,975,000
Effective tax rate															18.40%	14.80%	18.30%
Tax savings due to the tax holiday															$ 11,500,000	$ 13,200,000	$ 4,700,000
Tax savings due to the tax holiday, per share															$ 0.05	$ 0.06	$ 0.02
Tax holiday expiration date															December 31, 2015
Accrued interest and penalties	500,000							600,000							$ 500,000	$ 600,000
Interest and penalties related to income tax															200,000	200,000	$ 200,000
Valuation allowance amount decrease/increase															1,300,000
Valuation allowance includes net deferred tax assets	43,039,000							41,737,000							43,039,000	41,737,000
U.S. Federal operating loss carryforwards	4,870,000														4,870,000
Net operating loss carryforward excess tax deductions related to stock based compensation	0														0
Tax credit carryforwards, approximately	121,200,000														121,200,000
Tax credits carryforwards	44,684,000							50,554,000							44,684,000	50,554,000
Unrecognized tax benefits	36,792,000							$ 30,418,000							36,792,000	$ 30,418,000	$ 21,203,000	$ 18,666,000
Unrecognized tax benefits, if recognized would impact effective tax rate	29,200,000														29,200,000
Unrecognized tax benefits, if recognized would impact valuation allowance	7,600,000														7,600,000
Decrease in unrecognized tax benefits															(7,600,000)
Deferred tax liability not been established	783,000,000														783,000,000
United States
Income Taxes [Line Items]
Tax credits carryforwards, business	43,200,000														43,200,000
Tax credits carryforwards	42,900,000														42,900,000
State and Local Jurisdiction
Income Taxes [Line Items]
Tax credits carryforwards	71,400,000														$ 71,400,000
Earliest Tax Year | United States
Income Taxes [Line Items]
Tax credit carryforward, expiration date															2,017
Earliest Tax Year | State and Local Jurisdiction
Income Taxes [Line Items]
Tax credit carryforward, expiration date															2,016
Latest Tax Year | United States
Income Taxes [Line Items]
Tax credit carryforward, expiration date															2,035
Latest Tax Year | State and Local Jurisdiction
Income Taxes [Line Items]
Tax credit carryforward, expiration date															2,030
Do Not Expire
Income Taxes [Line Items]
Alternative minimum tax credits carryforwards	6,600,000														$ 6,600,000
Do Not Expire | State and Local Jurisdiction
Income Taxes [Line Items]
Tax credits carryforwards	42,400,000														42,400,000
GenRad, Inc.
Income Taxes [Line Items]
U.S. Federal operating loss carryforwards	$ 4,900,000														$ 4,900,000
[1]	In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[2]	Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[3]	Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[4]	Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[5]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[6]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[7]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[8]	Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

Schedule of Reconciliation of E

Schedule of Reconciliation of Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
U.S. statutory federal tax rate	35.00%	35.00%	35.00%
Foreign taxes	(16.50%)	(58.10%)	(11.40%)
Goodwill impairment		36.30%
U.S. research and development credit	(3.00%)	(7.90%)	(7.20%)
Uncertain tax positions	2.10%	7.90%	4.20%
Valuation allowance			0.40%
State income taxes, net of federal tax benefit	0.40%	(0.10%)	0.10%
Other, net	0.40%	1.70%	(2.80%)
Effective tax rate, Total	18.40%	14.80%	18.30%

Schedule of Components of Defer

Schedule of Components of Deferred Tax Assets Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Tax credits	$ 44,684	$ 50,554
Pension liabilities	31,742	30,036
Inventory valuations	29,445	29,105
Accruals	26,563	23,323
Deferred revenue	10,232	10,242
Equity compensation	9,674	11,131
Net operating loss carryforwards	7,989	10,989
Vacation accrual	7,354	7,425
Other	502	1,725
Gross deferred tax assets	168,185	174,530
Less: valuation allowance	(43,039)	(41,737)
Total deferred tax assets	125,146	132,793
Intangible assets	(68,433)	(64,871)
Depreciation	(20,541)	(24,905)
Marketable securities	(458)	(1,599)
Total deferred tax liabilities	(89,432)	(91,375)
Net deferred assets	$ 35,714	$ 41,418

Summary of Operating Loss Carry

Summary of Operating Loss Carryforwards (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Operating Loss Carryforwards [Line Items]
U.S. Federal operating loss carryforwards	$ 4,870
State Operating Loss Carryforwards	103,156
Foreign Operating Loss Carryforwards	8,345
2,016
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	925
2,017
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	10,649
2,018
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	8,563
2,019
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	1,203
2,020
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	269
2021-2025
Operating Loss Carryforwards [Line Items]
U.S. Federal operating loss carryforwards	4,870
State Operating Loss Carryforwards	35,777
2026-2030
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	39,411
Beyond 2,030
Operating Loss Carryforwards [Line Items]
State Operating Loss Carryforwards	6,359
Foreign Operating Loss Carryforwards	143
Non-Expiring
Operating Loss Carryforwards [Line Items]
Foreign Operating Loss Carryforwards	$ 8,202

Schedule of Unrecognized Tax Be

Schedule of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
Beginning balance, as of January 1	$ 30,418	$ 21,203	$ 18,666
Tax positions for current year	6,626	8,414	4,586
Tax positions for prior years	792	3,781	2,112
Tax positions for prior years	(708)	(2,480)	(4,161)
Settlements with tax authorities	(336)	(500)
Ending balance as of December 31	$ 36,792	$ 30,418	$ 21,203

Operating Segment, Geographi123

Operating Segment, Geographic and Significant Customer Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015Segment	Dec. 31, 2014Customer	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating segments | Segment	4
Number of customer accounted for more than consolidated revenue | Customer		0
Customer 1 | Consolidated Revenue | Revenue from Rights Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage	13.00%		12.00%

Schedule of Segment Information

Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended														12 Months Ended
		Dec. 31, 2015		Oct. 04, 2015	[3]	Jul. 05, 2015	[4]	Apr. 05, 2015	Dec. 31, 2014		Sep. 28, 2014	[5],[8]	Jun. 29, 2014	[5]	Mar. 30, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues		$ 318,444	[1],[2]	$ 465,994		$ 512,739		$ 342,401	$ 323,236	[5],[6],[7]	$ 478,010		$ 525,567		$ 321,010	$ 1,639,578	[9]	$ 1,647,824	[9]	$ 1,427,933	[9]
Income (loss) before taxes		(8,857)	[1],[2]	$ 87,408		$ 132,136		$ 42,438	(124,813)	[5],[6],[7]	$ 100,670		$ 121,392		$ (1,873)	253,124	[10],[11]	95,376	[10],[11]	201,922	[10],[11]
Total assets	[12]	2,548,674							2,538,520							2,548,674		2,538,520		2,629,824
Property additions																89,878		168,982		106,731
Depreciation and amortization expense																140,772		152,544		150,687
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues																1,201,530		1,300,790		1,023,041
Income (loss) before taxes	[10],[11]															260,154		255,803		153,797
Total assets	[12]	610,869							580,501							610,869		580,501		632,840
Property additions																79,052		159,783		94,303
Depreciation and amortization expense																64,415		84,990		72,472
Wireless Test
Segment Reporting Information [Line Items]
Revenues																184,572		184,535		251,871
Income (loss) before taxes	[10],[11]															(13,830)		(116,196)		23,153
Total assets	[12]	427,880							478,974							427,880		478,974		645,001
Property additions																3,133		3,730		5,358
Depreciation and amortization expense																53,440		53,308		51,675
System Test
Segment Reporting Information [Line Items]
Revenues																211,584		162,499		153,021
Income (loss) before taxes	[10],[11]															25,101		12,116		3,115
Total assets	[12]	102,547							95,105							102,547		95,105		79,983
Property additions																6,228		5,469		7,070
Depreciation and amortization expense																4,390		5,399		5,180
Industrial Automation
Segment Reporting Information [Line Items]
Revenues																41,892
Income (loss) before taxes	[10],[11]															(7,574)
Total assets	[12]	344,260														344,260
Property additions																1,465
Depreciation and amortization expense																14,500
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) before taxes	[10],[11]															(10,727)		(56,347)		21,857
Total assets	[12]	$ 1,063,118							$ 1,383,940							1,063,118		1,383,940		1,272,000
Depreciation and amortization expense																$ 4,027		$ 8,847		$ 21,360
[1]	In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[2]	Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[3]	Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[4]	Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[5]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[6]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[7]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[8]	Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[9]	Revenues attributable to a country are based on location of customer site.
[10]	Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges and goodwill impairment charges.
[11]	Interest income, interest expense, other (income) expense, net, contingent consideration adjustments and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations.
[12]	Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.

Schedule of Segment Reporting I

Schedule of Segment Reporting Information by Segment Charges (Detail) - USD ($) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Jan. 31, 2014

Dec. 31, 2015

Oct. 04, 2015

Jul. 05, 2015

Dec. 31, 2014

Sep. 28, 2014

Jun. 29, 2014

[5]

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Segment Reporting Information [Line Items]

Restructuring and other

$ 5,204

[1],[2]

$ 261

[3]

$ (385)

[4]

$ 1,198

[5],[6],[7]

$ (405)

[5],[8]

$ 572

$ 5,080

$ 1,365

$ 2,080

Goodwill impairment charge

98,897

[5],[6],[7]

98,897

0

Contingent consideration adjustment

2,489

(630)

Gain from the sale of an equity investment

5,406

34,212

Stock based compensation expense

$ 6,600

30,451

40,307

36,612

Selling and Administrative

Segment Reporting Information [Line Items]

Stock based compensation expense

18,024

26,486

19,822

Universal Robots

Segment Reporting Information [Line Items]

Contingent consideration adjustment

5,339

5,339

Acquisition related costs

1,104

ZTEC Instruments, Inc.

Segment Reporting Information [Line Items]

Contingent consideration adjustment

$ (1,600)

$ (630)

(1,600)

(630)

Avionics Interface Technologies, LLC

Segment Reporting Information [Line Items]

Contingent consideration adjustment

$ (300)

$ (1,000)

(1,250)

Acquisition related costs

372

System Test

Segment Reporting Information [Line Items]

Cost of revenues-inventory charge

8,324

2,125

4,168

Restructuring and other

1,037

742

1,431

Goodwill impairment charge

$ 0

Semiconductor Test

Segment Reporting Information [Line Items]

Cost of revenues-inventory charge

10,508

14,389

5,218

Restructuring and other

499

490

1,016

Wireless Test

Segment Reporting Information [Line Items]

Cost of revenues-inventory charge

2,500

5,679

7,206

Restructuring and other

565

82

Goodwill impairment charge

98,897

Industrial Automation

Segment Reporting Information [Line Items]

Cost of revenues-inventory step-up

[9]

1,567

Corporate And Eliminations

Segment Reporting Information [Line Items]

Restructuring and other

198

(449)

Corporate And Eliminations | Restructuring and other

Segment Reporting Information [Line Items]

Acquisition related costs

1,104

372

Corporate And Eliminations | Other (income) expense, net

Segment Reporting Information [Line Items]

Gain from the sale of an equity investment

(5,406)

$ (34,212)

Corporate And Eliminations | Selling and Administrative

Segment Reporting Information [Line Items]

Stock based compensation expense

[10]

6,598

Corporate And Eliminations | Universal Robots | Restructuring and other

Segment Reporting Information [Line Items]

Contingent consideration adjustment

5,339

Corporate And Eliminations | ZTEC Instruments, Inc. | Restructuring and other

Segment Reporting Information [Line Items]

Contingent consideration adjustment

(1,600)

$ (630)

Corporate And Eliminations | Avionics Interface Technologies, LLC | Restructuring and other

Segment Reporting Information [Line Items]

Contingent consideration adjustment

$ (1,250)

[1]

In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[2]

Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[3]

Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[4]

Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[5]

Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.

[6]

In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.

[7]

In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[8]

Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[9]

Included in the cost of revenues for the years ended December 31, 2015 is the cost for purchase accounting inventory step-up.

[10]

Expense related to the January 2014 retirement of Teradyne's former chief executive officer; see Note N: "Stock-Based Compensation."

Schedule of Revenues by Country

Schedule of Revenues by Country (Detail) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2015

[1],[2]

Oct. 04, 2015

[3]

Jul. 05, 2015

[4]

Apr. 05, 2015

Dec. 31, 2014

[5],[6],[7]

Sep. 28, 2014

[5],[8]

Jun. 29, 2014

[5]

Mar. 30, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

$ 318,444

$ 465,994

$ 512,739

$ 342,401

$ 323,236

$ 478,010

$ 525,567

$ 321,010

$ 1,639,578

[9]

$ 1,647,824

[9]

$ 1,427,933

[9]

TAIWAN

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

436,389

495,942

265,472

CHINA

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

264,898

292,145

323,564

UNITED STATES

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

217,386

213,104

230,178

JAPAN

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

128,228

63,761

81,806

KOREA

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

120,224

145,608

119,286

Europe

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

111,903

111,043

90,797

SINGAPORE

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

105,216

119,421

114,765

PHILIPPINES

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

96,103

68,662

63,392

MALAYSIA

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

76,707

83,910

86,900

THAILAND

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

59,104

44,117

32,209

Rest Of The World

Revenues from External Customers and Long-Lived Assets [Line Items]

Revenue from unaffiliated customers

[9]

$ 23,420

$ 10,111

$ 19,564

[1]

In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[2]

Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[3]

Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.

[4]

Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[5]

Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.

[6]

In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.

[7]

In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[8]

Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.

[9]

Revenues attributable to a country are based on location of customer site.

Schedule of Long-Lived Assets b

Schedule of Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		$ 273,414	$ 329,038
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		198,424	206,334
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	[1]	$ 74,990	$ 122,704
[1]	As of December 31, 2015 and 2014, long-lived assets attributable to Singapore were $39.9 million and $99.2 million, respectively.

Schedule of Long-Lived Asset128

Schedule of Long-Lived Assets by Geographic Area (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 273,414	$ 329,038
SINGAPORE
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 39,900	$ 99,200

Stock Repurchase Program - Addi

Stock Repurchase Program - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands	1 Months Ended	12 Months Ended
	Nov. 30, 2010	Dec. 31, 2015	Jan. 31, 2015
Stock Repurchase Programs [Line Items]
Repurchase of stock, shares	2,600	15,621
Repurchase of stock, value	$ 31,200,000	$ 299,949,000
Common stock average price	$ 11.84	$ 19.20
Maximum
Stock Repurchase Programs [Line Items]
Stock repurchase program - shares authorized to repurchase	$ 200,000,000		$ 500,000,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - Subsequent Event	1 Months Ended
	Jan. 31, 2016$ / shares
Subsequent Event [Line Items]
Dividends payable, amount per share	$ 0.06
Dividends payable, date to be paid	Mar. 21, 2016
Dividends payable, record date	Feb. 26, 2016

Consolidated Quarterly Statemen

Consolidated Quarterly Statements of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended														12 Months Ended
	Dec. 31, 2015	[1],[2]	Oct. 04, 2015	[3]	Jul. 05, 2015	[4]	Apr. 05, 2015	Dec. 31, 2014	[5],[6],[7]	Sep. 28, 2014	[5],[8]	Jun. 29, 2014	[5]	Mar. 30, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Quarterly Financial Information [Line Items]
Products	$ 244,510		$ 386,488		$ 437,243		$ 272,325	$ 253,162		$ 402,987		$ 452,488		$ 255,386	$ 1,340,566		$ 1,364,024		$ 1,154,922
Services	73,934		79,506		75,496		70,076	70,074		75,023		73,079		65,624	299,012		283,800		273,011
Total revenues	318,444		465,994		512,739		342,401	323,236		478,010		525,567		321,010	1,639,578	[9]	1,647,824	[9]	1,427,933	[9]
Cost of products	120,322		170,963		181,491		118,996	131,337		182,591		202,411		124,448	591,772		640,787		499,030
Cost of services	32,096		36,405		32,680		30,982	31,673		34,298		32,743		29,515	132,163		128,229		120,102
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	152,418		207,368		214,171		149,978	163,010		216,889		235,154		153,963	723,935		769,016		619,132
Gross profit	166,026		258,626		298,568		192,423	160,226		261,121		290,413		167,047	915,643		878,808		808,801
Engineering and development	70,941		74,027		75,832		71,450	79,188		71,953		73,414		67,085	292,250		291,639		264,055
Selling and administrative	79,718		77,481		77,073		72,041	91,157		73,064		77,489		78,003	306,313		319,713		279,560
Goodwill impairment								98,897									98,897		0
Acquired intangible assets amortization	19,911		20,053		15,258		13,808	15,957		18,271		18,271		18,271	69,031		70,771		72,447
Restructuring and other	5,204		261		(385)			1,198		(405)		572			5,080		1,365		2,080
Total operating expenses	175,774		171,822		167,778		157,299	286,397		162,883		169,746		163,359	672,674		782,385		618,142
Income (loss) from operations	(9,748)		86,804		130,790		35,124	(126,171)		98,238		120,667		3,688	242,969		96,423		190,659
Interest income	(2,017)		(1,708)		(1,674)		(1,816)	(2,035)		(1,922)		(1,266)		(1,036)	(7,214)		(6,259)		(4,129)
Interest expense	762		508		444		162	214		144		159		6,417	1,876		6,934		26,097
Other (income) expense, net	364		596		(116)		(5,660)	463		(654)		382		180	(4,817)		372		(33,231)
(Loss) income before income taxes	(8,857)		87,408		132,136		42,438	(124,813)		100,670		121,392		(1,873)	253,124	[10],[11]	95,376	[10],[11]	201,922	[10],[11]
Income tax (benefit) provision	(8,216)		15,955		29,257		9,651	(21,002)		17,721		20,187		(2,802)	46,647		14,104		36,975
Net income (loss)	$ (641)		$ 71,453		$ 102,879		$ 32,787	$ (103,811)		$ 82,949		$ 101,205		$ 929	$ 206,477		$ 81,272		$ 164,947
Net income (loss) per common share-basic	$ 0		$ 0.34		$ 0.48		$ 0.15	$ (0.48)		$ 0.40		$ 0.52		$ 0	$ 0.98		$ 0.40		$ 0.86
Net income (loss) per common share-diluted	0		0.34		0.48		0.15	(0.48)		0.38		0.47		0	0.97		0.37		$ 0.70
Cash dividend declared per common share	$ 0.06		$ 0.06		$ 0.06		$ 0.06	$ 0.06		$ 0.06		$ 0.06		$ 0	$ 0.24		$ 0.18
[1]	In the fourth quarter ended December 31, 2015, Teradyne recorded pension and post retirement net actuarial losses of $17.7 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[2]	Restructuring and other includes a $5.3 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and a $(0.3) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[3]	Restructuring and other includes a $(1.0) million fair value adjustment to decrease the AIT acquisition contingent consideration.
[4]	Restructuring and other includes a $(1.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[5]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[6]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[7]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.
[8]	Restructuring and other includes a $(0.6) million fair value adjustment to decrease the ZTEC acquisition contingent consideration.
[9]	Revenues attributable to a country are based on location of customer site.
[10]	Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges and goodwill impairment charges.
[11]	Interest income, interest expense, other (income) expense, net, contingent consideration adjustments and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations.

Consolidated Quarterly State132

Consolidated Quarterly Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2015	Oct. 04, 2015	Jul. 05, 2015	Dec. 31, 2014		Sep. 28, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information [Line Items]
Changes to fair value of contingent consideration							$ 2,489	$ (630)
Pension and post retirement net actuarial losses (gain)	$ 17,732			$ 46,564			17,732	46,564	$ (10,340)
Goodwill impairment				$ 98,897	[1],[2],[3]			98,897	$ 0
ZTEC Instruments, Inc.
Quarterly Financial Information [Line Items]
Changes to fair value of contingent consideration			$ (1,600)			$ (630)	(1,600)	$ (630)
Universal Robots
Quarterly Financial Information [Line Items]
Changes to fair value of contingent consideration	5,339						5,339
Avionics Interface Technologies, LLC
Quarterly Financial Information [Line Items]
Changes to fair value of contingent consideration	$ (300)	$ (1,000)					$ (1,250)
[1]	Dividends declared by Teradyne's Board of Directors were paid in the second, third and fourth quarters of 2014.
[2]	In the fourth quarter ended December 31, 2014, Teradyne recorded a goodwill impairment charge of $98.9 million in its Wireless Test segment.
[3]	In the fourth quarter ended December 31, 2014, Teradyne recorded pension and post retirement net actuarial losses of $46.6 million. See Note B: "Accounting Policies" for a discussion of our accounting policy.

Valuation and Qualifying Acc133

Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 2,491	$ 2,912	$ 4,118
Additions Charged to Cost and Expenses		55	69
Deductions	84	476	1,275	[1]
Balance at End of Period	2,407	2,491	2,912
Inventory Reserve
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	111,252	115,857	141,838
Additions Charged to Cost and Expenses	21,332	22,193	16,592
Other	1,680	7,064	2,568
Deductions	14,888	33,862	45,141
Balance at End of Period	119,376	111,252	115,857
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	41,737	40,386	55,446
Additions Charged to Cost and Expenses	1,322	1,380	4,546
Deductions	20	29	19,606
Balance at End of Period	$ 43,039	$ 41,737	$ 40,386
[1]	Based upon an improvement in the aging of accounts receivables in 2013, Teradyne reduced its allowance for doubtful accounts by approximately $1 million.

Valuation and Qualifying Acc134

Valuation and Qualifying Accounts (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2013USD ($)
Valuation and Qualifying Accounts Disclosure [Line Items]
Decrease in allowance for doubtful accounts	$ (1)