Teradyne (TER) 10-Q 11 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Apr. 01, 2018	May 07, 2018
Document Information
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Apr. 1, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	TER
Entity Registrant Name	TERADYNE, INC
Entity Central Index Key	97,210
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		191,316,067

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Apr. 01, 2018		Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 637,873		$ 429,843
Marketable securities	860,526		1,347,979
Accounts receivable, less allowance for doubtful accounts of $2,206 and $2,219 at April 1, 2018 and December 31, 2017, respectively	413,978		272,783
Inventories, net	131,857		107,525
Prepayments and other current assets	112,191		112,151
Total current assets	2,156,425		2,270,281
Property, plant and equipment, net	281,284		268,447
Marketable securities	89,259		125,926
Deferred tax assets	77,705		84,026
Retirement plans assets	17,928		17,491
Other assets	12,479		12,275
Acquired intangible assets, net	84,413		79,088
Goodwill	275,700		252,011
Total assets	2,995,193	[1]	3,109,545
Current liabilities:
Accounts payable	103,950		86,393
Accrued employees' compensation and withholdings	86,292		141,694
Deferred revenue and customer advances	85,892		83,614
Other accrued liabilities	64,782		59,083
Contingent consideration	15,581		24,497
Income taxes payable	34,828		59,055
Total current liabilities	391,325		454,336
Retirement plans liabilities	124,689		119,776
Long-term deferred revenue and customer advances	21,726		30,127
Deferred tax liabilities	6,185		6,720
Long-term other accrued liabilities	16,683		10,273
Long-term contingent consideration			20,605
Long-term income taxes payable	160,181		148,075
Long-term debt	369,421		365,987
Total liabilities	1,090,210		1,155,899
Commitments and contingencies (See Note Q)
SHAREHOLDERS' EQUITY
Common stock, $0.125 par value, 1,000,000 shares authorized; 193,808 and 195,548 shares issued and outstanding at April 1, 2018 and December 31, 2017, respectively	24,226		24,444
Additional paid-in capital	1,638,756		1,638,413
Accumulated other comprehensive income	25,881		18,776
Retained earnings	216,120		272,013
Total shareholders' equity	1,904,983		1,953,646
Total liabilities and shareholders' equity	$ 2,995,193		$ 3,109,545
[1]	Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Accounts receivable, less allowance for doubtful accounts	$ 2,206	$ 2,219
Common stock, par value	$ 0.125	$ 0.125
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	193,808,000	195,548,000
Common stock, shares outstanding	193,808,000	195,548,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Revenues:
Products	$ 403,925	$ 373,204
Services	83,542	83,709
Total revenues	487,467	456,913
Cost of revenues:
Cost of products	180,958	154,883
Cost of services	36,677	37,014
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	217,635	191,897
Gross profit	269,832	265,016
Operating expenses:
Selling and administrative	90,505	84,792
Engineering and development	74,408	75,978
Acquired intangible assets amortization	7,698	7,952
Restructuring and other	(313)	2,511
Total operating expenses	172,298	171,233
Income from operations	97,534	93,783
Non-operating (income) expense:
Interest income	(5,981)	(3,520)
Interest expense	6,890	5,402
Other (income) expense, net	805	(115)
Income before income taxes	95,820	92,016
Income tax provision	8,846	6,795
Net income	$ 86,974	$ 85,221
Net income per common share:
Basic	$ 0.45	$ 0.43
Diluted	$ 0.43	$ 0.42
Weighted average common shares-basic	195,255	200,005
Weighted average common shares-diluted	203,484	201,936
Cash dividend declared per common share	$ 0.09	$ 0.07

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Net income	$ 86,974	$ 85,221
Other comprehensive income, net of tax:
Foreign currency translation adjustment, net of tax of $0, $0, respectively	10,541	8,963
Available-for-sale marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(718), $420, respectively	(2,687)	513
Less: Reclassification adjustment for losses (gains) included in net income, net of tax of $78, $(64), respectively	1,668	(95)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total	(1,019)	418
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 of $(18), $(38), respectively	(61)	(68)
Other comprehensive income (loss)	9,461	9,313
Comprehensive income	$ 96,435	$ 94,534

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Foreign currency translation adjustments, tax	$ 0	$ 0
Unrealized (losses) gains on marketable securities arising during period, tax	(718)	420
Reclassification adjustment for gains included in net income, tax	78	(64)
Amortization of net prior service (credit) cost included in net periodic pension and post-retirement expense/income, tax	$ (18)	$ (38)

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Cash flows from operating activities:
Net income	$ 86,974	$ 85,221
Adjustments to reconcile net income to net cash used for operating activities:
Depreciation	16,336	16,143
Amortization	9,204	11,070
Stock-based compensation	9,544	8,945
Provision for excess and obsolete inventory	3,522	2,726
Deferred taxes	8,696	(3,477)
Contingent consideration adjustment	(4,968)	634
Other	1,393	2
Changes in operating assets and liabilities, net of business acquired:
Accounts receivable	(140,747)	(123,792)
Inventories	(21,017)	(62,152)
Prepayments and other assets	(679)	1,104
Accounts payable and other accrued expenses	(46,706)	(7,553)
Deferred revenue and customer advances	9,644	(3,333)
Retirement plans contributions	(1,020)	(947)
Income taxes	(12,106)	14,288
Net cash used for operating activities	(81,930)	(61,121)
Cash flows from investing activities:
Purchases of property, plant and equipment	(34,797)	(22,066)
Purchases of marketable securities	(490,324)	(153,317)
Proceeds from sales of marketable securities	800,671	213,593
Proceeds from maturities of marketable securities	212,698	88,184
Acquisition of business, net of cash acquired	(25,356)
Net cash provided by investing activities	462,892	126,394
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	10,654	15,084
Repurchase of common stock	(134,276)	(37,730)
Payments related to net settlement of employee stock compensation awards	(19,629)	(12,289)
Dividend payments	(17,588)	(14,021)
Payments of contingent consideration	(13,571)	(1,050)
Net cash used for financing activities	(174,410)	(50,006)
Effects of exchange rate changes on cash and cash equivalents	1,478	1,595
Increase in cash and cash equivalents	208,030	16,862
Cash and cash equivalents at beginning of period	429,843	307,884
Cash and cash equivalents at end of period	$ 637,873	$ 324,746

The Company

The Company	3 Months Ended
	Apr. 01, 2018
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 robotic arms, and advanced robotic control software used by global manufacturing and light industrial customers to improve quality, increase manufacturing and material handling 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”); • industrial automation (“Industrial Automation”) products; and • wireless test (“Wireless Test”) systems.

Accounting Policies

Accounting Policies	3 Months Ended
	Apr. 01, 2018
Accounting Policies	B. ACCOUNTING POLICIES Basis of Presentation The consolidated interim financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated. These interim financial statements are unaudited and reflect all normal recurring adjustments that are, in the opinion of management, necessary for the fair statement of such interim financial statements. Certain prior year amounts were reclassified to conform to the current year presentation. The December 31, 2017 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America. The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in Teradyne’s Annual Report on Form 10-K, Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the amounts reported in the financial statements. Actual results may differ significantly from these estimates. Revenue from Contracts with Customers Teradyne adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers” (“ASC 606”) “Revenue Recognition” (“ASC 605”) 10-K In accordance with ASC 606, Teradyne recognizes revenues, when or as control is transferred to a customer. Teradyne’s determination of revenue is dependent upon a five step process outlined below. Step 1: Identify the contract with the customer Teradyne accounts for a contract with a customer when there is written approval, the contract is committed, the rights of the parties, including payment terms, are identified, the contract has commercial substance and consideration is probable of collection. Step 2: Identify the performance obligations in the contract Teradyne periodically enters into contracts with its customers in which a customer may purchase a combination of goods and or services, such as products with extended warranty obligations. Teradyne determines performance obligations by assessing whether the products or services are distinct from the other elements of the contract. In order to be distinct the product or service must perform either on its own or with readily available resources and must be separate within the context of the contract. Step 3: Determine the transaction price Teradyne considers the amount stated on the face of the purchase order to be the transaction price. Teradyne does not have material variable consideration which could impact the stated purchase price agreed to by Teradyne and the customer. Step 4: Allocate the transaction price to the performance obligations in the contract Transaction price is allocated to each individual performance obligation based on the standalone selling price of that performance obligation. Teradyne uses standalone transactions when available to value each performance obligation. If standalone transactions are not available, Teradyne will estimate the standalone selling price through market assessments or cost plus a reasonable margin analysis. Any discounts from standalone selling price are spread proportionally to each performance obligation. Step 5: Recognize revenue when (or as) the entity satisfies a performance obligation In order to determine the appropriate timing for revenue recognition, Teradyne first determines if the transaction meets any of three criteria for over time recognition. If the transaction meets the criteria for over time recognition, Teradyne recognizes revenue as the good or service is delivered. Teradyne uses input variables such as hours or months utilized or costs incurred to determine the amount of revenue to recognize in a given period. Input variables are used as they best align consumption with benefit to the customer. For transactions which do not meet the criteria for over time recognition, Teradyne will recognize revenue at a point in time based on an assessment of the five criteria for transfer of control. Teradyne has concluded that revenue should be recognized when shipped or delivered based on contractual terms. Typically acceptance of Teradyne’s products and services is a formality as Teradyne delivers similar systems, instruments and robots to standard specifications. In cases where acceptance is not deemed a formality, Teradyne will defer revenue recognition until customer acceptance. Revenue recognized in accordance with ASC 606 was $483.2 million for the period ended April 1, 2018. Teradyne also recognized $4.3 million in revenue on leases of Teradyne systems which are accounted for outside of ASC 606. Disaggregation of Revenue The following table provides information about disaggregated revenue by primary geographical market, major product line and timing of revenue recognition. Semiconductor System Test Industrial Wireless Corporate Consolidated SOC (1) Memory Defense/ Aerospace Storage Production Board Test (in thousands) Three Months Ended April 1, 2018 Americas Point in Time $ 9,600 $ 2,862 $ 11,597 $ 279 $ 1,760 $ 14,373 $ 4,979 $ (221 ) $ 45,229 Over Time 8,791 696 6,188 — 757 89 112 — 16,633 Europe, Middle East and Africa Point in Time 12,125 139 1,497 — 4,037 22,573 1,041 — 41,412 Over Time 5,214 269 551 — 1,559 143 227 — 7,963 Asia Pacific Point in Time 224,851 66,273 101 10,122 1,861 11,583 13,664 — 328,455 Over Time 36,338 2,323 208 1,533 735 73 2,296 — 43,506 Lease Revenue 3,847 — — — 234 — 188 — 4,269 Total $ 300,766 $ 72,562 $ 20,142 $ 11,934 $ 10,943 $ 48,834 $ 22,507 $ (221 ) $ 487,467 (1) System on a chip (“SOC”) Performance Obligations Hardware Teradyne hardware consists primarily of semiconductor test systems and instruments, defense/aerospace test instrumentation and systems, storage test systems and instruments, circuit-board test and inspection systems and instruments, collaborative robots, and wireless test systems. The hardware includes a standard 12 month warranty. This warranty is not considered a distinct performance obligation because it does not obligate Teradyne to provide a separate service to the customer and it cannot be purchased separately. Teradyne’s hardware is recognized at a point in time upon transfer of control to the customer. Extended Warranty Customers have the option to purchase an extended warranty, which extends the warranty period for systems and robots beyond the one year standard warranty. The extended warranty is purchased in the same transaction as the system or robot purchase and is classified as a separate performance obligation which meets the criteria for over time recognition. The relative standalone selling price of the extended warranty is recognized ratably over the course of the extended warranty based on months completed. Training and Applications Support Teradyne sells training and applications support to customers either in standalone transactions or included with system purchases. The training and support allow the customer to use Teradyne’s systems efficiently and effectively. Training and applications support included in system orders are valued based on their standalone selling price and all training and applications support is recognized over time as the customer receives and consumes the benefit associated with each. Both are recognized using an input method of hours consumed as this best depicts the transfer of services to the customer. Service Agreements Service agreements are recognized ratably over the period of agreement based on months completed. Post-Contract Customer Support (“PCS”) Teradyne provides support services for certain systems and robots outside of warranty. These services include telephone support, bug fixes, and when-and-if Teradyne does not allow customer returns or provide refunds to customers for any products or services. Contract Balances The following table provides information about contract liabilities. Teradyne does not have material contract assets on the balance sheet. April 1, 2018 January 1, 2018 (as adjusted) Increase (in thousands) Deferred revenue and customer advances $ 85,892 $ 76,638 $ 9,254 Long-term deferred revenue and customer advances 21,726 20,848 878 The amount of revenue recognized during the quarter ended April 1, 2018 that was included within the deferred revenue and customer advances balance at January 1, 2018 was $21.8 million and primarily relates to extended warranties, training, application support, and PCS. Each of these represents a distinct performance obligation. Customers typically pay for these services net 30 to 60 days from the date that transfer of control of the associated system or product occurs. Remaining Performance Obligations Teradyne does not have material remaining performance obligations from contracts with an original expected duration of greater than one year. Significant Judgments Teradyne makes no significant judgements in determining the amount or timing of revenue recognition. Practical Expedients Teradyne has adopted the practical expedients available within ASC 340 “Other Assets and Deferred Costs” Teradyne has adopted the practical expedient which states an entity need not adjust the promised amount of consideration for the effects of a significant financing component if the entity expects, at contract inception, that the period between when the entity transfers a promised good or service to the customer and when the customer pays for that good or service will be one year or less. Teradyne does not have material payments associated with performance obligations outside this one year time frame. Impacts The following tables summarize the impact of ASC 606 to Teradyne’s consolidated financial statements. Differences are the result of timing differences between the recognition of revenue under ASC 606 and ASC 605 primarily with respect to software transactions deferred due to lack of vendor specific objective evidence of price under ASC 605 and Teradyne’s assessment of acceptance under ASC 606. Under Legacy GAAP Teradyne did not recognize revenue prior to acceptance if payment, title, or risk of loss was tied to acceptance. Under ASC 606, Teradyne recognizes revenue prior to receipt of acceptance if acceptance is deemed a formality. Condensed Consolidated Balance Sheet: April 1, 2018 As Adjustments to Recognize Legacy (in thousands) ASSETS Accounts receivable, less allowance for doubtful accounts $ 413,978 $ (67,728 ) $ 346,250 Inventories, net 131,857 27,749 159,606 Deferred tax assets 77,705 2,923 80,628 LIABILITIES Deferred revenue and customer advances $ 85,892 $ 4,990 $ 90,882 Income taxes payable 34,828 (5,167 ) 29,661 Long-term deferred revenue and customer advances 21,726 9,178 30,904 SHAREHOLDERS’ EQUITY Retained earnings $ 216,120 $ (46,057 ) $ 170,063 Condensed Consolidated Statement of Operation: Three months ended April 1, 2018 As Adjustments to Recognize Legacy (in thousands except per share amounts) Total revenues $ 487,467 $ (65,642 ) $ 421,825 Total cost of revenues 217,635 (27,749 ) 189,886 Income tax provision 8,846 (4,515 ) 4,331 Net income 86,974 (33,378 ) 53,596 Net income per common share: Basic $ 0.45 $ (0.17 ) $ 0.27 Diluted $ 0.43 $ (0.16 ) $ 0.26 Retirement Benefits In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost non-service non-service non-service Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): Contingencies and Litigation Teradyne may be subject to certain legal proceedings, lawsuits and other claims as discussed in Note Q: “Commitments and Contingencies.” Teradyne accrues for a loss contingency, including legal proceedings, lawsuits, pending claims and other legal matters, when the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, Teradyne accrues the amount at the low end of the range. Teradyne adjusts the accruals from time to time as additional information is received, but the loss incurred may be significantly greater than or less than the amount accrued. Loss contingencies are disclosed when they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	3 Months Ended
	Apr. 01, 2018
Recently Issued Accounting Pronouncements	C. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS On January 26, 2017, the FASB issued ASU 2017-04, “Intangibles – Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment.” one-step In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” “Leases.” of-use

Acquisitions

Acquisitions	3 Months Ended
	Apr. 01, 2018
Acquisitions	D. ACQUISITIONS Energid Technologies Corporation On February 26, 2018, Teradyne acquired all the issued and outstanding shares of Energid Technologies Corporation (“Energid”) for a total preliminary purchase price of approximately $27.6 million. Energid’s technology enables and simplifies the programming of complex robotic motions used in a wide variety of end markets, ranging from heavy industry to healthcare; utilizing both traditional robots and collaborative robots. The Energid acquisition was accounted for as a business combination and, accordingly, Energid’s results have been included in Teradyne’s Industrial Automation segment from the date of acquisition. As of the acquisition date, Teradyne’s preliminary purchase price allocation was goodwill of $15.7 million, acquired intangible assets of $10.9 million with an average estimated useful life of 6.1 years, and $1.0 million of net tangible assets. The acquisition was not material to our condensed consolidated financial statements.

Inventories

Inventories	3 Months Ended
	Apr. 01, 2018
Inventories	E. INVENTORIES Inventories, net consisted of the following at April 1, 2018 and December 31, 2017: April 1, December 31, (in thousands) Raw material $ 74,762 $ 62,668 Work-in-process 21,256 19,464 Finished Goods 35,839 25,393 $ 131,857 $ 107,525 Inventory reserves for the periods ending April 1, 2018 and December 31, 2017 were $103.4 million and $102.9 million, respectively.

Financial Instruments

Financial Instruments	3 Months Ended
	Apr. 01, 2018
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 Effective January 1, 2018, Teradyne adopted ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): On a quarterly basis, Teradyne reviews its investments to identify and evaluate those that have an indication of a potential other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include: • The length of time and the extent to which the market value has been less than cost; • The financial condition and near-term prospects of the issuer; and • The intent and ability to retain the investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. Teradyne uses the market and income approach techniques to value its financial instruments and there were no changes in valuation techniques during the three months ended April 1, 2018 and April 2, 2017. As defined in ASC 820-10, Fair Value Measurements and Disclosures, 820-10 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 is considered a Level 2 input; or 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. Teradyne’s available-for-sale Realized gains recorded in the three months ended April 1, 2018 and April 2, 2017 were $0.3 million and $0.3 million, respectively. Realized losses recorded in the three months ended April 1, 2018 and April 2, 2017 were $1.5 million and $0.2 million, respectively. Realized gains are included in interest income and realized losses are included in interest expense. Unrealized gains and losses on available-for-sale During the three months ended April 1, 2018 and April 2, 2017, 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 April 1, 2018 and December 31, 2017. April 1, 2018 Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in thousands) Assets Cash $ 155,543 $ — $ — $ 155,543 Cash equivalents 306,710 175,620 — 482,330 Available-for-sale U.S. Treasury securities — 611,946 — 611,946 Commercial paper — 252,158 — 252,158 Corporate debt securities — 44,218 — 44,218 U.S. government agency securities — 10,726 — 10,726 Certificates of deposit and time deposits — 4,824 — 4,824 Debt mutual funds 2,741 — — 2,741 Non-U.S. — 559 — 559 Equity securities: Mutual funds 22,613 — — 22,613 $ 487,607 $ 1,100,051 $ — $ 1,587,658 Derivative assets — 12 — 12 Total $ 487,607 $ 1,100,063 $ — $ 1,587,670 Liabilities Contingent consideration $ — $ — $ 15,581 $ 15,581 Derivative liabilities — 224 — 224 Total $ — $ 224 $ 15,581 $ 15,805 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 462,253 $ 175,620 $ — $ 637,873 Marketable securities — 860,526 — 860,526 Long-term marketable securities 25,354 63,905 — 89,259 Prepayments — 12 — 12 Total $ 487,607 $ 1,100,063 $ — $ 1,587,670 Liabilities . Other current liabilities $ — $ 224 $ — $ 224 Contingent consideration — — 15,581 15,581 Total $ — $ 224 $ 15,581 $ 15,805 December 31, 2017 Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in thousands) Assets Cash $ 197,955 $ — $ — $ 197,955 Cash equivalents 206,335 25,553 — 231,888 Available-for-sale U.S. Treasury securities — 855,795 — 855,795 Commercial paper — 282,840 — 282,840 Certificates of deposit and time deposits — 167,342 — 167,342 Corporate debt securities — 133,186 — 133,186 Equity and debt mutual funds 23,430 — — 23,430 U.S. government agency securities — 10,726 — 10,726 Non-U.S. — 586 — 586 $ 427,720 $ 1,476,028 $ — $ 1,903,748 Derivative assets — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Contingent consideration $ — $ — $ 45,102 $ 45,102 Derivative liabilities — 446 — 446 Total $ — $ 446 $ 45,102 $ 45,548 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 404,290 $ 25,553 $ — $ 429,843 Marketable securities — 1,347,979 — 1,347,979 Long-term marketable securities 23,430 102,496 — 125,926 Prepayments — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Other accrued liabilities $ — $ 446 $ — $ 446 Contingent consideration — — 24,497 24,497 Long-term contingent consideration — — 20,605 20,605 Total $ — $ 446 $ 45,102 $ 45,548 Changes in the fair value of Level 3 contingent consideration for the three months ended April 1, 2018 and April 2, 2017 were as follows: For the Three Months Ended April 1, April 2, (in thousands) Balance at beginning of period $ 45,102 $ 38,332 Payments (a) (24,553 ) (1,050 ) Fair value adjustment (b) (4,968 ) 634 Balance at end of period $ 15,581 $ 37,916 (a) In the three months ended April 1, 2018, Teradyne paid $24.6 million of contingent consideration for the earn-out earn-out (b) In the three months ended April 1, 2018, the fair value of contingent consideration for the earn-out earn-out The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instruments: Liability April 1, 2018 Valuation Technique Unobservable Inputs Weighted Average (in thousands) Contingent consideration (Universal Robots) $ 15,581 Monte Carlo Simulation Revenue for the period July 1, 13.0 % Discount Rate 3.8 % As of April 1, 2018, 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 maximum payment for the remaining Universal Robots revenue earn-out The carrying amounts and fair values of Teradyne’s financial instruments at April 1, 2018 and December 31, 2017 were as follows: April 1, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 637,873 $ 637,873 $ 429,843 $ 429,843 Marketable securities 949,785 949,785 1,473,905 1,473,905 Derivative assets 12 12 389 389 Liabilities Contingent consideration 15,581 15,581 45,102 45,102 Derivative liabilities 224 224 446 446 Convertible debt (1) 369,421 700,626 365,987 659,525 (1) The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion features. The fair values of accounts receivable, net and accounts payable approximate the carrying value due to the short-term nature of these instruments. The following table summarize the composition of available-for-sale April 1, 2018 Cost Unrealized Gain Unrealized (Loss) Fair Value Fair Market Value of Investments with Unrealized Losses (in thousands) U.S. Treasury securities $ 614,365 $ 19 $ (2,438 ) $ 611,946 $ 610,938 Commercial paper 252,579 17 (438 ) 252,158 249,871 Corporate debt securities 43,472 1,200 (454 ) 44,218 17,742 U.S. government agency securities 10,791 — (65 ) 10,726 10,726 Certificates of deposit and time deposits 4,820 4 — 4,824 — Debt mutual funds 2,799 — (58 ) 2,741 1,679 Non-U.S. 559 — — 559 — $ 929,385 $ 1,240 $ (3,453 ) $ 927,172 $ 890,956 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 861,794 $ 54 $ (1,322 ) $ 860,526 $ 847,446 Long-term marketable securities 67,591 1,186 (2,131 ) 66,646 43,510 $ 929,385 $ 1,240 $ (3,453 ) $ 927,172 $ 890,956 The following table summarize the composition of available-for-sale December 31, 2017 Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) U.S. Treasury securities $ 858,258 $ 72 $ (2,535 ) $ 855,795 $ 850,163 Commercial paper 283,009 18 (187 ) 282,840 258,933 Certificates of deposit and time deposits 167,523 6 (187 ) 167,342 138,340 Corporate debt securities 131,179 2,380 (373 ) 133,186 91,010 Equity and debt mutual funds 19,403 4,102 (75 ) 23,430 1,723 U.S. government agency securities 10,775 — (49 ) 10,726 10,726 Non-U.S. 582 4 — 586 — $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 1,349,970 $ 38 $ (2,029 ) $ 1,347,979 $ 1,288,844 Long-term marketable securities 120,759 6,544 (1,377 ) 125,926 62,052 $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 As of April 1, 2018, the fair market value of investments in debt securities with unrealized losses totaled $891.0 million. Of this value, $62.1 million had unrealized losses of $1.6 million for greater than one year and $828.9 million had unrealized losses of $1.9 million for less than one year. As of December 31, 2017, the fair market value of investments with unrealized losses totaled $1,350.9 million. Of this value, $141.0 million had unrealized losses of $1.2 million for greater than one year and $1,209.9 million had unrealized losses of $2.2 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 April 1, 2018 and December 31, 2017 were temporary. The contractual maturities of investments in debt securities held at April 1, 2018 were as follows: April 1, 2018 Cost Fair Market Value (in thousands) Due within one year $ 861,794 $ 860,526 Due after 1 year through 5 years 10,173 10,058 Due after 5 years through 10 years 14,583 13,823 Due after 10 years 40,036 40,024 Total $ 926,586 $ 924,431 Contractual maturities of investments in debt securities held at April 1, 2018 exclude $2.7 million of debt mutual funds as they do not have a contractual maturity date. Derivatives Teradyne conducts business in a number of foreign countries, with certain transactions denominated in local currencies. The purpose of Teradyne’s foreign currency management is to minimize the effect of exchange rate fluctuations on certain foreign currency denominated monetary assets and liabilities. Teradyne does not use derivative financial instruments for trading or speculative purposes. To minimize the effect of exchange rate fluctuations associated with the remeasurement of monetary assets and liabilities denominated in foreign currencies, Teradyne enters into foreign currency forward contracts. The change in fair value of these derivatives is recorded directly in earnings, and is used to offset the change in value of monetary assets and liabilities denominated in foreign currencies. The notional amount of foreign currency forward contracts at April 1, 2018 and December 31, 2017 was $108.8 million and $116.8 million, respectively. 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 April 1, 2018 and December 31, 2017: Balance Sheet Location April 1, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign currency forward contracts assets Prepayments $ 12 $ 389 Foreign currency forward contracts liabilities Other current liabilities (224 ) (446 ) Total derivatives $ (212 ) $ (57 ) The following table summarizes the effect of derivative instruments recognized in the statement of operations for the three months ended April 1, 2018 and April 2, 2017. Location of Losses Recognized in Statement of Operations For the Three Months Ended April 1, 2018 April 2, 2017 (in thousands) Derivatives not designated as hedging instruments: Foreign currency forward contracts Other (income) expense, net $ 1,575 $ 1,011 (1) The table does not reflect the corresponding gains and losses from the remeasurement of monetary assets and liabilities denominated in foreign currencies. (2) For the three months ended April 1, 2018 and April 2, 2017, net gains from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $0.6 million and $1.5 million, respectively. See Note G: “Debt” regarding derivatives related to the convertible senior notes.

Debt

Debt	3 Months Ended
	Apr. 01, 2018
Debt	G. DEBT Convertible Senior Notes On December 12, 2016, Teradyne completed a private offering of $460.0 million convertible senior unsecured notes (the “Notes”). The Notes will mature on December 15, 2023, unless earlier repurchased or converted. The Notes bear interest from December 12, 2016 at a rate of 1.25% per year payable semi-annually in arrears on June 15 and December 15 of each year, beginning on June 15, 2017. The Notes will be convertible at the option of the noteholders at any time prior to the close of business on the business day immediately preceding September 15, 2023, under the following circumstances: (1) during any calendar quarter beginning after March 31, 2017 (and only during such calendar quarter), if the closing sale price of Teradyne’s common stock, for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the trading price (as defined in the Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the closing sale price of the Teradyne’s common stock and the conversion rate on each such trading day; and (3) upon the occurrence of specified corporate events. On or after September 15, 2023 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances. Teradyne may satisfy its conversion obligation by paying or delivering cash, shares of its common stock or a combination of cash and shares of its common stock, at Teradyne’s election. As of December 31, 2017 the conversion price was approximately $31.80 per share of Teradyne’s common stock. The conversion rate is subject to adjustment under certain circumstances. Concurrent with the offering of the Notes, Teradyne entered into convertible note hedge transactions (the “Note Hedge Transactions”) with the initial purchasers or their affiliates (the “Option Counterparties”). The Note Hedge Transactions cover, subject to customary anti-dilution adjustments, the number of shares of the common stock that underlie the Notes, with a strike price equal to the conversion price of the Notes of $31.80. The Note Hedge Transactions cover, subject to customary anti-dilution adjustments, approximately 14.5 million shares of Teradyne’s common stock. The convertible note hedge is considered indexed to Teradyne’s stock as the terms of the Note Hedge Transactions do not contain an exercise contingency and the settlement amount equals the difference between the fair value of a fixed number of Teradyne’s shares and a fixed strike price. Because the only variable that can affect the settlement amount is Teradyne’s stock price, which is an input to the fair value of a fixed-for-fixed Separately and concurrent with the pricing of the Notes, Teradyne entered into warrant transactions with the Option Counterparties (the “Warrant Transactions”) in which it sold net-share-settled The Note Hedge Transactions are expected to reduce the potential dilution to Teradyne’s common stock upon any conversion of the Notes. However, the Warrant Transactions could separately have a dilutive effect to the extent that the market value per share of Teradyne’s common stock exceeds the applicable strike price of the warrant. The net cost of the Notes Hedge Transactions, after being partially offset by the proceeds from the sale of the warrants, was approximately $33 million. In connection with establishing their initial hedge of these convertible note hedge and warrant transactions, the Option Counterparties have entered into various derivative transactions with respect to Teradyne’s common stock and/or purchased shares of Teradyne’s common stock or other securities, including the Notes, concurrent with, or shortly after, the pricing of the Notes. In addition, the Option Counterparties may modify their hedge positions by entering into or unwinding various derivative transactions with respect to Teradyne’s common stock or by selling Teradyne’s common stock or other securities, including the Notes, in secondary market transactions (and may do so during any observation period related to the conversion of the Notes). These activities could adversely affect the value of Teradyne’s common stock and the Notes. Teradyne’s effective annual interest rate on the Notes will be approximately 5.0%. The Notes are classified as long-term debt in the balance sheet based on their December 15, 2023 maturity date. Debt issuance costs of approximately $7.2 million are being amortized to interest expense using the effective interest method over the seven year term of the Notes. As of April 1, 2018, unamortized debt issuance costs were approximately $6.0 million. The below tables represent the key components of Teradyne’s convertible senior notes: April 1, 2018 December 31, 2017 (in thousands) Debt Principal $ 460,000 $ 460,000 Unamortized discount 90,579 94,013 Net Carrying amount of convertible debt $ 369,421 $ 365,987 For the Three Months Ended April 1, 2018 April 2, 2017 (in thousands) Contractual interest expense on the coupon $ 1,438 $ 1,438 Amortization of the discount component and debt issue fees recognized as interest expense 3,434 3,268 Total interest expense on the convertible debt $ 4,872 $ 4,706 As of April 1, 2018, the remaining unamortized discount was $90.6 million, which will be amortized over 5.8 years using the effective interest rate method. The carrying amount of the equity component was $100.8 million. As of April 1, 2018, the conversion rate was equal to the initial conversion price of approximately $31.80 per share and the if-converted 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 statements of operations. As of May 11, 2018, 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 May 11, 2018, 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.

Prepayments

Prepayments	3 Months Ended
	Apr. 01, 2018
Prepayments	H. PREPAYMENTS Prepayments consist of the following and are included in prepayments on the balance sheet: April 1, December 31, (in thousands) Contract manufacturer and supplier prepayments $ 76,204 $ 82,503 Prepaid maintenance and other services 8,449 8,189 Prepaid taxes 9,938 5,039 Other prepayments 11,964 12,386 Total prepayments $ 106,555 $ 108,117

Deferred Revenue and Customer A

Deferred Revenue and Customer Advances	3 Months Ended
	Apr. 01, 2018
Deferred Revenue and Customer Advances	I. DEFERRED REVENUE AND CUSTOMER ADVANCES Deferred revenue and customer advances consist of the following and are included in short and long-term deferred revenue and customer advances on the balance sheet: April 1, December 31, (in thousands) Maintenance and training $ 59,365 $ 57,256 Extended warranty 24,590 24,438 Customer advances, undelivered elements and other 23,663 32,047 Total deferred revenue and customer advances $ 107,618 $ 113,741

Product Warranty

Product Warranty	3 Months Ended
	Apr. 01, 2018
Product Warranty	J. PRODUCT WARRANTY Teradyne generally provides a one-year For the Three Months Ended April 1, April 2, (in thousands) Balance at beginning of period $ 8,200 $ 7,203 Accruals for warranties issued during the period 3,063 3,021 Adjustments related to pre-existing (139 ) (471 ) Settlements made during the period (3,576 ) (2,699 ) Balance at end of period $ 7,548 $ 7,054 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 on the balance sheet. For the Three April 1, April 2, (in thousands) Balance at beginning of period $ 24,438 $ 28,200 Deferral of new extended warranty revenue 5,139 4,048 Recognition of extended warranty deferred revenue (4,987 ) (7,279 ) Balance at end of period $ 24,590 $ 24,969

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Apr. 01, 2018
Stock-Based Compensation	K. STOCK-BASED COMPENSATION Under Teradyne’s stock compensation plans, Teradyne grants 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 Commencing in January 2014, Teradyne granted performance-based restricted stock units (“PRSUs”) to its executive officers with a performance metric based on relative total shareholder return (“TSR”). For TSR grants issued in 2018 and 2017, Teradyne’s three-year TSR performance is measured against the New York Stock Exchange (“NYSE”) Composite Index. The final number of TSR PRSUs that vest will vary based upon the level of performance achieved from 200% to 0% of the target shares capped at four times the grant date value. The TSR PRSUs will vest upon the three-year anniversary of the grant date. 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 shorter of the three-year service period or the period from the grant date to the date described in the retirement provisions below. Compensation expense for employees meeting the retirement provisions prior to the grant date will be recognized in full on the date of the grant. 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 below. In January 2018 and 2017, Teradyne granted PRSUs to its executive officers with a performance metric based on three-year cumulative non-GAAP Non-GAAP non-cash non-recurring 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 all or a portion of 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. Except as set forth in the preceding sentence, no PRSUs will vest if the executive officer is no longer an employee at the end of the three-year period. During the three months ended April 1, 2018 and April 2, 2017, Teradyne granted 0.1 million and 0.1 million TSR PRSUs, respectively, with a grant date fair value of $54.85 and $35.66, respectively. The fair value was estimated using the Monte Carlo simulation model with the following assumptions: For the Three Months Ended April 1, April 2, Risk-free interest rate 2.2 % 1.5 % Teradyne volatility-historical 26.8 % 26.6 % NYSE Composite Index volatility-historical 12.4 % 13.4 % Dividend yield 0.8 % 1.0 % Expected volatility was based on the historical volatility of Teradyne’s stock and the NYSE Composite Index for the 2018 and 2017 grant over the most recent three year period. The risk-free interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield was based upon an estimated annual dividend amount of $0.36 per share for 2018 grants and $0.28 per share for 2017 grants, divided by Teradyne’s stock price on the grant date of $47.70 for the 2018 grant and $28.56 for the 2017 grant. During the three months ended April 1, 2018 and April 2, 2017, Teradyne granted 0.1 million and 0.1 million, respectively, of PBIT PRSUs with a grant date fair value of $46.62 and $27.72, respectively. During the three months ended April 1, 2018, Teradyne granted 0.5 million of service-based restricted stock unit awards to employees at a weighted average grant date fair value of $46.58 and 0.1 million of service-based stock options to executive officers at a weighted average grant date fair value of $12.17. During the three months ended April 2, 2017, Teradyne granted 0.8 million of service-based restricted stock unit awards to employees at a weighted average grant date fair value of $27.86 and 0.1 million of service-based stock options to executive officers at a weighted average grant date fair value of $7.13. Restricted stock unit awards granted to employees vest in equal annual installments over four years. Stock options vest in equal annual installments over four years and have a term of seven years from the date of grant. The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended April 1, April 2, Expected life (years) 5.0 5.0 Risk-free interest rate 2.4 % 2.0 % Volatility-historical 26.4 % 27.8 % Dividend yield 0.8 % 1.0 % Teradyne determined the stock options’ expected life based upon historical exercise data for executive officers, the age of the executive officers and the terms of the stock option grant. Volatility was determined using historical volatility for a period equal to the expected life. The risk-free interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield was based upon an estimated annual dividend amount of $0.36 per share for 2018 grants and $0.28 per share for 2017 grants divided by Teradyne’s stock price on the grant date of $47.70 for the 2018 grant and $28.56 for the 2017 grant.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Apr. 01, 2018
Accumulated Other Comprehensive Income	L. ACCUMULATED OTHER COMPREHENSIVE INCOME Changes in accumulated other comprehensive income, which are presented net of tax, consist of the following: For the Three Months Ended April 1, 2018 Foreign Currency Translation Adjustment Unrealized Gains (Losses) on Marketable Securities Retirement Plans Prior Service Credit Total (in thousands) Three Months Ended April 1, 2018 Balance at December 31, 2017, net of tax of $0, $1,815, $(932), respectively $ 15,919 $ 1,362 $ 1,495 $ 18,776 Other comprehensive income (loss) before reclassifications, net of tax of $0, $(718), $0, respectively 10,541 (2,687 ) — 7,854 Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $78, $(18), respectively — 1,668 (61 ) 1,607 Net current period other comprehensive income (loss), net of tax of $0, $(640), $(18), respectively 10,541 (1,019 ) (61 ) 9,461 Reclassification of income tax effects from the Tax Reform Act, net of tax of $0, $(691), $(78), respectively (a) — 691 78 769 Reclassification of unrealized gains on equity securities, net of tax of $0, $(902), $0, respectively (b) — (3,125 ) — (3,125 ) Balance at April 1, 2018, net of tax of $0, $(418), $(1,028), respectively $ 26,460 $ (2,091 ) $ 1,512 $ 25,881 (a) In the three months ended April 1, 2018, Teradyne early adopted the ASU 2018-02, “Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” (b) In the three months ended April 1, 2018, Teradyne adopted the ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): For the Three Months ended April 2, 2017 Foreign Currency Translation Adjustments Unrealized Gains (Losses) on Marketable Securities Retirement Plans Prior Service Credit Total (in thousands) Three Months Ended April 2, 2017 Balance at December 31, 2016, net of tax of $0, $209, $(778), respectively $ (21,921 ) $ (60 ) $ 1,767 $ (20,214 ) Other comprehensive income before reclassifications, net of tax of $0, $420,$0, respectively 8,963 513 — 9,476 Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(64), $(38), respectively — (95 ) (68 ) (163 ) Net current period other comprehensive income (loss), net of tax of $0, $356, $(38), respectively 8,963 418 (68 ) 9,313 Balance as April 2, 2017, net of tax of $0, $565, $(816), respectively $ (12,958 ) $ 358 $ 1,699 $ (10,901 ) Reclassifications out of accumulated other comprehensive income (loss) to the statement of operations for the three months ended April 1, 2018 and April 2, 2017 were as follows: Details about Accumulated Other Comprehensive (Loss) Income Components For the Three Months Ended Affected Line Item in the Statements of Operations April 1, April 2, (in thousands) Available-for-sale Unrealized (losses) gains, net of tax of $(78), $64, respectively $ (1,668 ) $ 95 Interest (expense) Defined benefit pension and postretirement plans: Amortization of prior service credit, net of tax of $18, $38, respectively 61 68 (a) Total reclassifications, net of tax of $(60), $102, respectively $ (1,607 ) $ 163 Net income (a) The amortization of prior service credit is included in the computation of net periodic pension cost and postretirement benefit; see Note P: “Retirement Plans.”

Goodwill and Acquired Intangibl

Goodwill and Acquired Intangible Assets	3 Months Ended
	Apr. 01, 2018
Goodwill and Acquired Intangible Assets	M. GOODWILL AND ACQUIRED INTANGIBLE ASSETS Goodwill Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, “Intangibles—Goodwill and Other” The changes in the carrying amount of goodwill by reportable segments for the three months ended April 1, 2018, were as follows: Wireless Test Industrial Automation System Test Semiconductor Test Total (in thousands) Balance at December 31, 2017 Goodwill $ 361,819 $ 233,519 $ 158,699 $ 260,540 $ 1,014,577 Accumulated impairment losses (353,843 ) — (148,183 ) (260,540 ) (762,566 ) 7,976 233,519 10,516 — 252,011 Energid acquisition — 15,654 — — 15,654 Foreign currency translation adjustment — 8,035 — — 8,035 Balance at April 1, 2018 Goodwill 361,819 257,208 158,699 260,540 1,038,266 Accumulated impairment losses (353,843 ) — (148,183 ) (260,540 ) (762,566 ) $ 7,976 $ 257,208 $ 10,516 $ — $ 275,700 Intangible Assets Teradyne reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful lives of these assets are no longer appropriate. Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet: April 1, 2018 Gross Carrying Amount (1) Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 276,417 $ (231,266 ) $ 3,214 $ 48,365 Customer relationships 96,771 (84,940 ) 340 12,171 Tradenames and trademarks 51,120 (28,108 ) 825 23,837 Non-compete 320 (280 ) — 40 Total intangible assets $ 424,628 $ (344,594 ) $ 4,379 $ 84,413 December 31, 2017 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 270,877 $ (226,190 ) $ 1,618 $ 46,305 Customer relationships 92,741 (83,585 ) 171 9,327 Tradenames and trademarks 50,100 (27,120 ) 416 23,396 Non-compete 320 (260 ) — 60 Total intangible assets $ 414,038 $ (337,155 ) $ 2,205 $ 79,088 (1) Gross carrying amount includes $10.9 million of Energid acquired intangible assets. Aggregate intangible asset amortization expense was $7.7 million and $8.0 million, respectively, for the three months ended April 1, 2018 and April 2, 2017. Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2018 (remainder) 24,236 2019 28,316 2020 13,171 2021 5,298 2022 4,493 Thereafter 8,899

Net Income per Common Share

Net Income per Common Share	3 Months Ended
	Apr. 01, 2018
Net Income per Common Share	N. NET INCOME PER COMMON SHARE The following table sets forth the computation of basic and diluted net income per common share: For the Three Months Ended April 1, 2018 April 2, 2017 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 86,974 $ 85,221 Weighted average common shares-basic 195,255 200,005 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) 4,398 — Convertible note hedge warrant shares (2) 1,830 — Restricted stock units 1,666 1,533 Stock options 321 390 Employee stock purchase plan 14 8 Dilutive potential common shares 8,229 1,931 Weighted average common shares-diluted 203,484 201,936 Net income per common share-basic $ 0.45 $ 0.43 Net income per common share-diluted $ 0.43 $ 0.42 (1) Incremental shares from 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 $31.80, multiplied by 14.5 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 $39.91, multiplied by 14.5 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. The computation of diluted net income per common share for the three months ended April 1, 2018 excludes the effect of the potential vesting of 0.4 million shares of restricted stock units because the effect would have been anti-dilutive. The computation of diluted net income per common share for the three months ended April 2, 2017 excludes the effect of the potential exercise of stock options to purchase approximately 0.1 million shares because the effect would have been anti-dilutive.

Restructuring and Other

Restructuring and Other	3 Months Ended
	Apr. 01, 2018
Restructuring and Other	O. RESTRUCTURING AND OTHER During the three months ended April 1, 2018, Teradyne recorded a $5.0 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $3.9 million recorded for employee severance charges, primarily in Semiconductor Test, and $0.8 million of acquisition related expenses. During the three months ended April 2, 2017, Teradyne recorded $2.5 million of restructuring and other charges of which $1.3 million was for a lease impairment of a Wireless Test facility in Sunnyvale, CA which was terminated in September 2017, $0.6 million was for employee severance charges, and $0.6 million for the increase in the fair value of the Universal Robots contingent consideration liability.

Retirement Plans

Retirement Plans	3 Months Ended
	Apr. 01, 2018
Defined Benefit Pension Plans
Retirement Plans	P. 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. In the three months ended April 1, 2018, Teradyne contributed $0.6 million to the U.S. supplemental executive defined benefit pension plan and $0.2 million to certain qualified pension plans for non-U.S. For the three months ended April 1, 2018 and April 2, 2017, Teradyne’s net periodic pension cost was comprised of the following: For the Three Months Ended April 1, 2018 April 2, 2017 United States Foreign United States Foreign (in thousands) Service cost $ 571 $ 213 $ 560 $ 185 Interest cost 2,997 186 3,312 163 Expected return on plan assets (3,369 ) (5 ) (3,000 ) (6 ) Amortization of prior service cost 14 — 18 — Total net periodic pension cost $ 213 $ 394 $ 890 $ 342 Postretirement Benefit Plan In addition to receiving pension benefits, Teradyne employees in the United States 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. For the three months ended April 1, 2018 and April 2, 2017, Teradyne’s net periodic postretirement benefit cost (income) was comprised of the following: For the Three Ended April 1, April 2, (in thousands) Service cost $ 9 $ 10 Interest cost 50 50 Amortization of prior service credit (93 ) (124 ) Special termination benefits 1,626 — Total net periodic postretirement benefit cost (income) $ 1,592 $ (64 )

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Apr. 01, 2018
Commitments and Contingencies	Q. COMMITMENTS AND CONTINGENCIES Purchase Commitments As of April 1, 2018, Teradyne had entered into purchase commitments for certain components and materials. The purchase commitments covered by the agreements aggregate to approximately $285.8 million, of which $275.7 million is for less than one year. Legal Claims Teradyne is subject to various legal proceedings and claims which have arisen in the ordinary course of business. In the opinion of management, the ultimate disposition of these matters will not have a material adverse effect on Teradyne’s results of operations, financial condition or cash flows.

Income Taxes

Income Taxes	3 Months Ended
	Apr. 01, 2018
Income Taxes	R. INCOME TAXES The effective tax rate for the three months ended April 1, 2018 and April 2, 2017 was 9.2% and 7.4%, respectively. The increase in the effective tax rate from the three months ended April 2, 2017 to the three months ended April 1, 2018 primarily resulted from a projected shift in the geographic distribution of income which increased income subject to taxation in the U.S. relative to lower tax rate jurisdictions and a reduction in discrete tax benefits recognized. These increases were partially offset by the benefit of the reduction in the U.S. corporate tax rate from 35% to 21% and the U.S. foreign derived intangible income deduction. The effective tax rates for the three months ended April 1, 2018 and April 2, 2017 differed from the expected federal statutory rate primarily because of the favorable effect of statutory rates applicable to income earned outside the United States. The tax rate for the three months ended April 1, 2018 and April 2, 2017 was also reduced by the benefit from U.S. research and development tax credits, partially offset by additions to the uncertain tax positions for transfer pricing, both of which are included in the projected annual effective tax rate. Discrete tax benefits recorded in the three months ended April 1, 2018 amounted to $8.3 million composed of $7.6 million from stock based compensation and $0.7 million of other discrete tax benefits. Discrete tax expense amounted to $2.3 million composed of $1.7 million from the remeasurement of deferred tax assets as a result of reductions in tax rates and $0.6 million of other discrete tax expenses. The $7.6 million of discrete benefit from stock based compensation included $7.4 million of excess tax benefits recognized pursuant to ASU No. 2016-09 Discrete tax benefits recorded in the three months ended April 2, 2017 amounted to $7.0 million of which $5.5 million resulted from stock based compensation, $0.7 million related to U.S. research and development tax credits and $0.8 million from other discrete tax benefits. The $5.5 million of discrete benefit from stock based compensation included $5.2 million of excess tax benefits recognized pursuant to ASU No. 2016-09 On a quarterly basis, Teradyne evaluates the realizability of the deferred tax assets by jurisdiction and assesses the need for a valuation allowance. As of April 1, 2018, Teradyne believes that it will ultimately realize the deferred tax assets recorded on the condensed consolidated balance sheet. However, should Teradyne believe that it is more-likely-than-not As of April 1, 2018 and December 31, 2017, Teradyne had $37.3 million and $36.3 million, respectively, of reserves for uncertain tax positions. The $1.0 million net increase in reserves for uncertain tax positions is primarily composed of additions related to transfer pricing exposures and U.S. research and development tax credits. Teradyne is currently under examination by the Internal Revenue Service. The timing of resolution and closure of the tax audit is highly unpredictable. Given the uncertainty, it is reasonably possible that the balance of unrecognized tax benefits could significantly change within the next twelve months. However, an estimate of the range of reasonably possible adjustments cannot presently be made. Teradyne recognizes interest and penalties related to income tax matters in income tax expense. As of April 1, 2018 and December 31, 2017, $0.3 million and $0.3 million, respectively, of interest and penalties were accrued for uncertain tax positions. For the three months ended April 1, 2018, an expense of $0.03 million was recorded for interest and penalties related to income tax items. For the three months ended April 2, 2017, a benefit of $0.1 million was recorded for interest and penalties related to income tax items. Teradyne qualifies for a tax holiday in Singapore by fulfilling the requirements of an agreement with the Singapore Economic Development Board under which certain headcount and spending requirements must be met. The tax savings due to the tax holiday for the three months ended April 1, 2018 was $3.0 million, or $0.01 per diluted share. The tax savings due to the tax holiday for the three months ended April 2, 2017 was $4.7 million, or $0.02 per diluted share. The tax holiday is scheduled to expire on December 31, 2020. In the fourth quarter of 2017, Teradyne recorded a provisional amount of $186.0 million of additional income tax expense which represents Teradyne’s best estimate of the impact of the Tax Cuts and Jobs Act of 2017 (the “Tax Reform Act”) in accordance with Teradyne’s understanding of the Tax Reform Act and guidance available at that time. The $186.0 million is composed of expense of $161.0 million related to the one-time

Segment Information

Segment Information	3 Months Ended
	Apr. 01, 2018
Segment Information	S. SEGMENT INFORMATION Teradyne has four operating segments (Semiconductor Test, System Test, Industrial Automation and Wireless Test), which are its reportable segments. The Semiconductor Test segment includes operations related to the design, manufacturing and marketing of semiconductor test products and services. The 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 Industrial Automation segment includes operations related to the design, manufacturing and marketing of collaborative robotic arms and advanced robotic control software. The Wireless Test segment includes operations related to the design, manufacturing and marketing of wireless test products and services. Each operating segment has a segment manager who is directly accountable to and maintains regular contact with Teradyne’s chief operating decision maker (Teradyne’s chief executive officer) to discuss operating activities, financial results, forecasts, and plans for the segment. Teradyne evaluates performance based on several factors, of which the primary financial measure is business segment income (loss) before income taxes. The accounting policies of the business segments in effect are described in Note B: “Accounting Policies” in Teradyne’s Annual Report on Form 10-K Segment information for the three months ended April 1, 2018 and April 2, 2017 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate and Other Consolidated (in thousands) Three Months Ended April 1, 2018 Revenues $ 373,328 $ 43,019 $ 48,834 $ 22,507 $ (221 ) $ 487,467 Income before income taxes (1)(2) 88,079 5,888 784 464 605 95,820 Total assets (3) 758,737 90,785 406,557 59,739 1,679,375 2,995,193 Three Months Ended April 2, 2017 Revenues $ 355,528 $ 39,845 $ 36,272 $ 25,268 $ — $ 456,913 Income (loss) before income taxes (1)(2) 97,966 (2,759 ) (2,571 ) 1,532 (2,152 ) 92,016 Total assets (3) 740,334 106,754 331,016 61,356 1,602,820 2,842,280 (1) Included in Corporate and Other are: contingent consideration adjustments, severance charges, interest income, interest expense, net foreign exchange gains (losses), and acquisitions related charges. (2) Included in the income (loss) before income taxes for each of the segments are charges and credits related to restructuring and other and inventory 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 and credits in the following line items in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Restructuring and other—employee severance $ 3,761 $ (265 ) Cost of revenues—inventory charge 2,166 1,319 Included in the System Test segment are charges in the following line item in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Cost of revenues—inventory charge $ 320 $ 885 Included in the Industrial Automation segment are charges in the following line item in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Cost of revenues—inventory charge $ 200 $ — Restructuring and other—employee severance 120 624 Included in the Wireless Test segment are charges in the following line items in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Cost of revenues—inventory charge $ 836 $ 522 Restructuring and other—employee severance — 1,313 Included in Corporate and Other are charges and credits in the following line items in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Restructuring and other—Universal Robots contingent consideration adjustment $ (4,968 ) $ 634 Restructuring and other—acquisition related expense 774 — Restructuring and other—employee severance — 205

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Apr. 01, 2018
Shareholders' Equity	T. SHAREHOLDERS’ EQUITY Stock Repurchase Program In January 2018, Teradyne’s Board of Directors cancelled the December 2016 stock repurchase program and authorized a new stock repurchase program for up to $1.5 billion of common stock. Teradyne intends to repurchase $750 million in 2018. During the three months ended April 1, 2018, Teradyne repurchased 2.9 million shares of common stock for $134.3 million at an average price of $45.69 per share. In December 2016, the Board of Directors approved a $500 million share repurchase authorization which commenced on January 1, 2017. During the three months ended April 2, 2017, Teradyne repurchased 1.3 million shares of common stock for $37.7 million at an average price of $29.38 per share. The total price includes commissions and is recorded as a reduction to retained earnings. Dividend Holders of Teradyne’s common stock are entitled to receive dividends when they are declared by Teradyne’s Board of Directors. In January 2018, Teradyne’s Board of Directors declared a quarterly cash dividend of $0.09 per share. Dividend payments for the three months ended April 1, 2018 were $17.6 million. In January 2017, Teradyne’s Board of Directors declared a quarterly cash dividend of $0.07 per share. Dividend payments for the three months ended April 2, 2017 were $14.0 million. 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.

Subsequent Events

Subsequent Events	3 Months Ended
	Apr. 01, 2018
Subsequent Events	U. SUBSEQUENT EVENTS On April 25, 2018, Teradyne acquired all the issued and outstanding shares of Mobile Industrial Robots ApS (“MiR”), a Danish limited liability company located in Odense, Denmark, for an aggregate purchase price of approximately $148 million net of cash acquired, and up to an additional approximately $124 million payable upon the achievement of certain revenue and profit performance targets through 2020. The fair value of assets and liabilities acquired has not been disclosed because Teradyne has not completed the valuation. MiR is the leading maker of collaborative autonomous mobile robots for industrial applications. MiR will be part of Teradyne’s Industrial Automation segment.

Accounting Policies (Policies)

Accounting Policies (Policies)	3 Months Ended
	Apr. 01, 2018
Basis of Presentation	Basis of Presentation The consolidated interim financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated. These interim financial statements are unaudited and reflect all normal recurring adjustments that are, in the opinion of management, necessary for the fair statement of such interim financial statements. Certain prior year amounts were reclassified to conform to the current year presentation. The December 31, 2017 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America. The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in Teradyne’s Annual Report on Form 10-K,
Preparation of Financial Statements and Use of Estimates	Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the amounts reported in the financial statements. Actual results may differ significantly from these estimates.
Revenue from Contracts with Customers	Revenue from Contracts with Customers Teradyne adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers” (“ASC 606”) “Revenue Recognition” (“ASC 605”) 10-K In accordance with ASC 606, Teradyne recognizes revenues, when or as control is transferred to a customer. Teradyne’s determination of revenue is dependent upon a five step process outlined below. Step 1: Identify the contract with the customer Teradyne accounts for a contract with a customer when there is written approval, the contract is committed, the rights of the parties, including payment terms, are identified, the contract has commercial substance and consideration is probable of collection. Step 2: Identify the performance obligations in the contract Teradyne periodically enters into contracts with its customers in which a customer may purchase a combination of goods and or services, such as products with extended warranty obligations. Teradyne determines performance obligations by assessing whether the products or services are distinct from the other elements of the contract. In order to be distinct the product or service must perform either on its own or with readily available resources and must be separate within the context of the contract. Step 3: Determine the transaction price Teradyne considers the amount stated on the face of the purchase order to be the transaction price. Teradyne does not have material variable consideration which could impact the stated purchase price agreed to by Teradyne and the customer. Step 4: Allocate the transaction price to the performance obligations in the contract Transaction price is allocated to each individual performance obligation based on the standalone selling price of that performance obligation. Teradyne uses standalone transactions when available to value each performance obligation. If standalone transactions are not available, Teradyne will estimate the standalone selling price through market assessments or cost plus a reasonable margin analysis. Any discounts from standalone selling price are spread proportionally to each performance obligation. Step 5: Recognize revenue when (or as) the entity satisfies a performance obligation In order to determine the appropriate timing for revenue recognition, Teradyne first determines if the transaction meets any of three criteria for over time recognition. If the transaction meets the criteria for over time recognition, Teradyne recognizes revenue as the good or service is delivered. Teradyne uses input variables such as hours or months utilized or costs incurred to determine the amount of revenue to recognize in a given period. Input variables are used as they best align consumption with benefit to the customer. For transactions which do not meet the criteria for over time recognition, Teradyne will recognize revenue at a point in time based on an assessment of the five criteria for transfer of control. Teradyne has concluded that revenue should be recognized when shipped or delivered based on contractual terms. Typically acceptance of Teradyne’s products and services is a formality as Teradyne delivers similar systems, instruments and robots to standard specifications. In cases where acceptance is not deemed a formality, Teradyne will defer revenue recognition until customer acceptance. Revenue recognized in accordance with ASC 606 was $483.2 million for the period ended April 1, 2018. Teradyne also recognized $4.3 million in revenue on leases of Teradyne systems which are accounted for outside of ASC 606. Disaggregation of Revenue The following table provides information about disaggregated revenue by primary geographical market, major product line and timing of revenue recognition. Semiconductor System Test Industrial Wireless Corporate Consolidated SOC (1) Memory Defense/ Aerospace Storage Production Board Test (in thousands) Three Months Ended April 1, 2018 Americas Point in Time $ 9,600 $ 2,862 $ 11,597 $ 279 $ 1,760 $ 14,373 $ 4,979 $ (221 ) $ 45,229 Over Time 8,791 696 6,188 — 757 89 112 — 16,633 Europe, Middle East and Africa Point in Time 12,125 139 1,497 — 4,037 22,573 1,041 — 41,412 Over Time 5,214 269 551 — 1,559 143 227 — 7,963 Asia Pacific Point in Time 224,851 66,273 101 10,122 1,861 11,583 13,664 — 328,455 Over Time 36,338 2,323 208 1,533 735 73 2,296 — 43,506 Lease Revenue 3,847 — — — 234 — 188 — 4,269 Total $ 300,766 $ 72,562 $ 20,142 $ 11,934 $ 10,943 $ 48,834 $ 22,507 $ (221 ) $ 487,467 (1) System on a chip (“SOC”) Performance Obligations Hardware Teradyne hardware consists primarily of semiconductor test systems and instruments, defense/aerospace test instrumentation and systems, storage test systems and instruments, circuit-board test and inspection systems and instruments, collaborative robots, and wireless test systems. The hardware includes a standard 12 month warranty. This warranty is not considered a distinct performance obligation because it does not obligate Teradyne to provide a separate service to the customer and it cannot be purchased separately. Teradyne’s hardware is recognized at a point in time upon transfer of control to the customer. Extended Warranty Customers have the option to purchase an extended warranty, which extends the warranty period for systems and robots beyond the one year standard warranty. The extended warranty is purchased in the same transaction as the system or robot purchase and is classified as a separate performance obligation which meets the criteria for over time recognition. The relative standalone selling price of the extended warranty is recognized ratably over the course of the extended warranty based on months completed. Training and Applications Support Teradyne sells training and applications support to customers either in standalone transactions or included with system purchases. The training and support allow the customer to use Teradyne’s systems efficiently and effectively. Training and applications support included in system orders are valued based on their standalone selling price and all training and applications support is recognized over time as the customer receives and consumes the benefit associated with each. Both are recognized using an input method of hours consumed as this best depicts the transfer of services to the customer. Service Agreements Service agreements are recognized ratably over the period of agreement based on months completed. Post-Contract Customer Support (“PCS”) Teradyne provides support services for certain systems and robots outside of warranty. These services include telephone support, bug fixes, and when-and-if Teradyne does not allow customer returns or provide refunds to customers for any products or services. Contract Balances The following table provides information about contract liabilities. Teradyne does not have material contract assets on the balance sheet. April 1, 2018 January 1, 2018 (as adjusted) Increase (in thousands) Deferred revenue and customer advances $ 85,892 $ 76,638 $ 9,254 Long-term deferred revenue and customer advances 21,726 20,848 878 The amount of revenue recognized during the quarter ended April 1, 2018 that was included within the deferred revenue and customer advances balance at January 1, 2018 was $21.8 million and primarily relates to extended warranties, training, application support, and PCS. Each of these represents a distinct performance obligation. Customers typically pay for these services net 30 to 60 days from the date that transfer of control of the associated system or product occurs. Remaining Performance Obligations Teradyne does not have material remaining performance obligations from contracts with an original expected duration of greater than one year. Significant Judgments Teradyne makes no significant judgements in determining the amount or timing of revenue recognition. Practical Expedients Teradyne has adopted the practical expedients available within ASC 340 “Other Assets and Deferred Costs” Teradyne has adopted the practical expedient which states an entity need not adjust the promised amount of consideration for the effects of a significant financing component if the entity expects, at contract inception, that the period between when the entity transfers a promised good or service to the customer and when the customer pays for that good or service will be one year or less. Teradyne does not have material payments associated with performance obligations outside this one year time frame. Impacts The following tables summarize the impact of ASC 606 to Teradyne’s consolidated financial statements. Differences are the result of timing differences between the recognition of revenue under ASC 606 and ASC 605 primarily with respect to software transactions deferred due to lack of vendor specific objective evidence of price under ASC 605 and Teradyne’s assessment of acceptance under ASC 606. Under Legacy GAAP Teradyne did not recognize revenue prior to acceptance if payment, title, or risk of loss was tied to acceptance. Under ASC 606, Teradyne recognizes revenue prior to receipt of acceptance if acceptance is deemed a formality. Condensed Consolidated Balance Sheet: April 1, 2018 As Adjustments to Recognize Legacy (in thousands) ASSETS Accounts receivable, less allowance for doubtful accounts $ 413,978 $ (67,728 ) $ 346,250 Inventories, net 131,857 27,749 159,606 Deferred tax assets 77,705 2,923 80,628 LIABILITIES Deferred revenue and customer advances $ 85,892 $ 4,990 $ 90,882 Income taxes payable 34,828 (5,167 ) 29,661 Long-term deferred revenue and customer advances 21,726 9,178 30,904 SHAREHOLDERS’ EQUITY Retained earnings $ 216,120 $ (46,057 ) $ 170,063 Condensed Consolidated Statement of Operation: Three months ended April 1, 2018 As Adjustments to Recognize Legacy (in thousands except per share amounts) Total revenues $ 487,467 $ (65,642 ) $ 421,825 Total cost of revenues 217,635 (27,749 ) 189,886 Income tax provision 8,846 (4,515 ) 4,331 Net income 86,974 (33,378 ) 53,596 Net income per common share: Basic $ 0.45 $ (0.17 ) $ 0.27 Diluted $ 0.43 $ (0.16 ) $ 0.26
Retirement Benefits	Retirement Benefits In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost non-service non-service non-service
Financial Assets and Financial Liabilities	Financial Assets and Financial Liabilities In January 2016, the FASB issued ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10):
Contingencies and Litigation	Contingencies and Litigation Teradyne may be subject to certain legal proceedings, lawsuits and other claims as discussed in Note Q: “Commitments and Contingencies.” Teradyne accrues for a loss contingency, including legal proceedings, lawsuits, pending claims and other legal matters, when the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, Teradyne accrues the amount at the low end of the range. Teradyne adjusts the accruals from time to time as additional information is received, but the loss incurred may be significantly greater than or less than the amount accrued. Loss contingencies are disclosed when they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Accounting Policies (Tables)

Accounting Policies (Tables)	3 Months Ended
	Apr. 01, 2018
Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition	The following table provides information about disaggregated revenue by primary geographical market, major product line and timing of revenue recognition. Semiconductor System Test Industrial Wireless Corporate Consolidated SOC (1) Memory Defense/ Aerospace Storage Production Board Test (in thousands) Three Months Ended April 1, 2018 Americas Point in Time $ 9,600 $ 2,862 $ 11,597 $ 279 $ 1,760 $ 14,373 $ 4,979 $ (221 ) $ 45,229 Over Time 8,791 696 6,188 — 757 89 112 — 16,633 Europe, Middle East and Africa Point in Time 12,125 139 1,497 — 4,037 22,573 1,041 — 41,412 Over Time 5,214 269 551 — 1,559 143 227 — 7,963 Asia Pacific Point in Time 224,851 66,273 101 10,122 1,861 11,583 13,664 — 328,455 Over Time 36,338 2,323 208 1,533 735 73 2,296 — 43,506 Lease Revenue 3,847 — — — 234 — 188 — 4,269 Total $ 300,766 $ 72,562 $ 20,142 $ 11,934 $ 10,943 $ 48,834 $ 22,507 $ (221 ) $ 487,467 (1) System on a chip (“SOC”)
Information about Contract Liabilities	The following table provides information about contract liabilities. Teradyne does not have material contract assets on the balance sheet. April 1, 2018 January 1, 2018 (as adjusted) Increase (in thousands) Deferred revenue and customer advances $ 85,892 $ 76,638 $ 9,254 Long-term deferred revenue and customer advances 21,726 20,848 878
ASU 2014-09
Summarize Impact of ASC 606 to Consolidated Financial Statements	The following tables summarize the impact of ASC 606 to Teradyne’s consolidated financial statements. Differences are the result of timing differences between the recognition of revenue under ASC 606 and ASC 605 primarily with respect to software transactions deferred due to lack of vendor specific objective evidence of price under ASC 605 and Teradyne’s assessment of acceptance under ASC 606. Under Legacy GAAP Teradyne did not recognize revenue prior to acceptance if payment, title, or risk of loss was tied to acceptance. Under ASC 606, Teradyne recognizes revenue prior to receipt of acceptance if acceptance is deemed a formality. Condensed Consolidated Balance Sheet: April 1, 2018 As Adjustments to Recognize Legacy (in thousands) ASSETS Accounts receivable, less allowance for doubtful accounts $ 413,978 $ (67,728 ) $ 346,250 Inventories, net 131,857 27,749 159,606 Deferred tax assets 77,705 2,923 80,628 LIABILITIES Deferred revenue and customer advances $ 85,892 $ 4,990 $ 90,882 Income taxes payable 34,828 (5,167 ) 29,661 Long-term deferred revenue and customer advances 21,726 9,178 30,904 SHAREHOLDERS’ EQUITY Retained earnings $ 216,120 $ (46,057 ) $ 170,063 Condensed Consolidated Statement of Operation: Three months ended April 1, 2018 As Adjustments to Recognize Legacy (in thousands except per share amounts) Total revenues $ 487,467 $ (65,642 ) $ 421,825 Total cost of revenues 217,635 (27,749 ) 189,886 Income tax provision 8,846 (4,515 ) 4,331 Net income 86,974 (33,378 ) 53,596 Net income per common share: Basic $ 0.45 $ (0.17 ) $ 0.27 Diluted $ 0.43 $ (0.16 ) $ 0.26

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Apr. 01, 2018
Composition of Inventories, Net	Inventories, net consisted of the following at April 1, 2018 and December 31, 2017: April 1, December 31, (in thousands) Raw material $ 74,762 $ 62,668 Work-in-process 21,256 19,464 Finished Goods 35,839 25,393 $ 131,857 $ 107,525

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Apr. 01, 2018
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 April 1, 2018 and December 31, 2017. April 1, 2018 Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in thousands) Assets Cash $ 155,543 $ — $ — $ 155,543 Cash equivalents 306,710 175,620 — 482,330 Available-for-sale U.S. Treasury securities — 611,946 — 611,946 Commercial paper — 252,158 — 252,158 Corporate debt securities — 44,218 — 44,218 U.S. government agency securities — 10,726 — 10,726 Certificates of deposit and time deposits — 4,824 — 4,824 Debt mutual funds 2,741 — — 2,741 Non-U.S. — 559 — 559 Equity securities: Mutual funds 22,613 — — 22,613 $ 487,607 $ 1,100,051 $ — $ 1,587,658 Derivative assets — 12 — 12 Total $ 487,607 $ 1,100,063 $ — $ 1,587,670 Liabilities Contingent consideration $ — $ — $ 15,581 $ 15,581 Derivative liabilities — 224 — 224 Total $ — $ 224 $ 15,581 $ 15,805 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 462,253 $ 175,620 $ — $ 637,873 Marketable securities — 860,526 — 860,526 Long-term marketable securities 25,354 63,905 — 89,259 Prepayments — 12 — 12 Total $ 487,607 $ 1,100,063 $ — $ 1,587,670 Liabilities . Other current liabilities $ — $ 224 $ — $ 224 Contingent consideration — — 15,581 15,581 Total $ — $ 224 $ 15,581 $ 15,805 December 31, 2017 Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in thousands) Assets Cash $ 197,955 $ — $ — $ 197,955 Cash equivalents 206,335 25,553 — 231,888 Available-for-sale U.S. Treasury securities — 855,795 — 855,795 Commercial paper — 282,840 — 282,840 Certificates of deposit and time deposits — 167,342 — 167,342 Corporate debt securities — 133,186 — 133,186 Equity and debt mutual funds 23,430 — — 23,430 U.S. government agency securities — 10,726 — 10,726 Non-U.S. — 586 — 586 $ 427,720 $ 1,476,028 $ — $ 1,903,748 Derivative assets — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Contingent consideration $ — $ — $ 45,102 $ 45,102 Derivative liabilities — 446 — 446 Total $ — $ 446 $ 45,102 $ 45,548 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 404,290 $ 25,553 $ — $ 429,843 Marketable securities — 1,347,979 — 1,347,979 Long-term marketable securities 23,430 102,496 — 125,926 Prepayments — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Other accrued liabilities $ — $ 446 $ — $ 446 Contingent consideration — — 24,497 24,497 Long-term contingent consideration — — 20,605 20,605 Total $ — $ 446 $ 45,102 $ 45,548
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	Changes in the fair value of Level 3 contingent consideration for the three months ended April 1, 2018 and April 2, 2017 were as follows: For the Three Months Ended April 1, April 2, (in thousands) Balance at beginning of period $ 45,102 $ 38,332 Payments (a) (24,553 ) (1,050 ) Fair value adjustment (b) (4,968 ) 634 Balance at end of period $ 15,581 $ 37,916 (a) In the three months ended April 1, 2018, Teradyne paid $24.6 million of contingent consideration for the earn-out earn-out (b) In the three months ended April 1, 2018, the fair value of contingent consideration for the earn-out earn-out
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 instruments: Liability April 1, 2018 Valuation Technique Unobservable Inputs Weighted Average (in thousands) Contingent consideration (Universal Robots) $ 15,581 Monte Carlo Simulation Revenue for the period July 1, 13.0 % Discount Rate 3.8 %
Schedule of Carrying Amounts and Fair Values of Financial Instruments	The carrying amounts and fair values of Teradyne’s financial instruments at April 1, 2018 and December 31, 2017 were as follows: April 1, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 637,873 $ 637,873 $ 429,843 $ 429,843 Marketable securities 949,785 949,785 1,473,905 1,473,905 Derivative assets 12 12 389 389 Liabilities Contingent consideration 15,581 15,581 45,102 45,102 Derivative liabilities 224 224 446 446 Convertible debt (1) 369,421 700,626 365,987 659,525 (1) The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion features.
Schedule of Available-for-Sale Marketable Securities	The following table summarize the composition of available-for-sale April 1, 2018 Cost Unrealized Gain Unrealized (Loss) Fair Value Fair Market Value of Investments with Unrealized Losses (in thousands) U.S. Treasury securities $ 614,365 $ 19 $ (2,438 ) $ 611,946 $ 610,938 Commercial paper 252,579 17 (438 ) 252,158 249,871 Corporate debt securities 43,472 1,200 (454 ) 44,218 17,742 U.S. government agency securities 10,791 — (65 ) 10,726 10,726 Certificates of deposit and time deposits 4,820 4 — 4,824 — Debt mutual funds 2,799 — (58 ) 2,741 1,679 Non-U.S. 559 — — 559 — $ 929,385 $ 1,240 $ (3,453 ) $ 927,172 $ 890,956 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 861,794 $ 54 $ (1,322 ) $ 860,526 $ 847,446 Long-term marketable securities 67,591 1,186 (2,131 ) 66,646 43,510 $ 929,385 $ 1,240 $ (3,453 ) $ 927,172 $ 890,956 The following table summarize the composition of available-for-sale December 31, 2017 Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) U.S. Treasury securities $ 858,258 $ 72 $ (2,535 ) $ 855,795 $ 850,163 Commercial paper 283,009 18 (187 ) 282,840 258,933 Certificates of deposit and time deposits 167,523 6 (187 ) 167,342 138,340 Corporate debt securities 131,179 2,380 (373 ) 133,186 91,010 Equity and debt mutual funds 19,403 4,102 (75 ) 23,430 1,723 U.S. government agency securities 10,775 — (49 ) 10,726 10,726 Non-U.S. 582 4 — 586 — $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 1,349,970 $ 38 $ (2,029 ) $ 1,347,979 $ 1,288,844 Long-term marketable securities 120,759 6,544 (1,377 ) 125,926 62,052 $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896
Contractual Maturities of Investments in Debt Securities Held	The contractual maturities of investments in debt securities held at April 1, 2018 were as follows: April 1, 2018 Cost Fair Market Value (in thousands) Due within one year $ 861,794 $ 860,526 Due after 1 year through 5 years 10,173 10,058 Due after 5 years through 10 years 14,583 13,823 Due after 10 years 40,036 40,024 Total $ 926,586 $ 924,431
Schedule of Derivative Instruments in Statement of Financial Position at Fair Value	The following table summarizes the fair value of derivative instruments as of April 1, 2018 and December 31, 2017: Balance Sheet Location April 1, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign currency forward contracts assets Prepayments $ 12 $ 389 Foreign currency forward contracts liabilities Other current liabilities (224 ) (446 ) Total derivatives $ (212 ) $ (57 )
Schedule of Effect of Derivative Instruments on Statement of Operations Recognized	The following table summarizes the effect of derivative instruments recognized in the statement of operations for the three months ended April 1, 2018 and April 2, 2017. Location of Losses Recognized in Statement of Operations For the Three Months Ended April 1, 2018 April 2, 2017 (in thousands) Derivatives not designated as hedging instruments: Foreign currency forward contracts Other (income) expense, net $ 1,575 $ 1,011 (1) The table does not reflect the corresponding gains and losses from the remeasurement of monetary assets and liabilities denominated in foreign currencies. (2) For the three months ended April 1, 2018 and April 2, 2017, net gains from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $0.6 million and $1.5 million, respectively.

Debt (Tables)

Debt (Tables)	3 Months Ended
	Apr. 01, 2018
Components of Convertible Senior Notes	The below tables represent the key components of Teradyne’s convertible senior notes: April 1, 2018 December 31, 2017 (in thousands) Debt Principal $ 460,000 $ 460,000 Unamortized discount 90,579 94,013 Net Carrying amount of convertible debt $ 369,421 $ 365,987 For the Three Months Ended April 1, 2018 April 2, 2017 (in thousands) Contractual interest expense on the coupon $ 1,438 $ 1,438 Amortization of the discount component and debt issue fees recognized as interest expense 3,434 3,268 Total interest expense on the convertible debt $ 4,872 $ 4,706

Prepayments (Tables)

Prepayments (Tables)	3 Months Ended
	Apr. 01, 2018
Schedule of Prepayments	Prepayments consist of the following and are included in prepayments on the balance sheet: April 1, December 31, (in thousands) Contract manufacturer and supplier prepayments $ 76,204 $ 82,503 Prepaid maintenance and other services 8,449 8,189 Prepaid taxes 9,938 5,039 Other prepayments 11,964 12,386 Total prepayments $ 106,555 $ 108,117

Deferred Revenue and Customer35

Deferred Revenue and Customer Advances (Tables)	3 Months Ended
	Apr. 01, 2018
Deferred Revenue and Customer Advances	Deferred revenue and customer advances consist of the following and are included in short and long-term deferred revenue and customer advances on the balance sheet: April 1, December 31, (in thousands) Maintenance and training $ 59,365 $ 57,256 Extended warranty 24,590 24,438 Customer advances, undelivered elements and other 23,663 32,047 Total deferred revenue and customer advances $ 107,618 $ 113,741

Product Warranty (Tables)

Product Warranty (Tables)	3 Months Ended
	Apr. 01, 2018
Other Accrued Liabilities	The warranty balance below is included in other accrued liabilities on the balance sheet. For the Three Months Ended April 1, April 2, (in thousands) Balance at beginning of period $ 8,200 $ 7,203 Accruals for warranties issued during the period 3,063 3,021 Adjustments related to pre-existing (139 ) (471 ) Settlements made during the period (3,576 ) (2,699 ) Balance at end of period $ 7,548 $ 7,054
Extended Product Warranty of Short and Long-Term Deferred Revenue and Customer Advances	The balance below is included in short and long-term deferred revenue and customer advances on the balance sheet. For the Three April 1, April 2, (in thousands) Balance at beginning of period $ 24,438 $ 28,200 Deferral of new extended warranty revenue 5,139 4,048 Recognition of extended warranty deferred revenue (4,987 ) (7,279 ) Balance at end of period $ 24,590 $ 24,969

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Apr. 01, 2018
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: For the Three Months Ended April 1, April 2, Risk-free interest rate 2.2 % 1.5 % Teradyne volatility-historical 26.8 % 26.6 % NYSE Composite Index volatility-historical 12.4 % 13.4 % Dividend yield 0.8 % 1.0 %
Fair Value of Stock Options Using Assumptions	The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended April 1, April 2, Expected life (years) 5.0 5.0 Risk-free interest rate 2.4 % 2.0 % Volatility-historical 26.4 % 27.8 % Dividend yield 0.8 % 1.0 %

Accumulated Other Comprehensi38

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Apr. 01, 2018
Changes in Accumulated Other Comprehensive Income	Changes in accumulated other comprehensive income, which are presented net of tax, consist of the following: For the Three Months Ended April 1, 2018 Foreign Currency Translation Adjustment Unrealized Gains (Losses) on Marketable Securities Retirement Plans Prior Service Credit Total (in thousands) Three Months Ended April 1, 2018 Balance at December 31, 2017, net of tax of $0, $1,815, $(932), respectively $ 15,919 $ 1,362 $ 1,495 $ 18,776 Other comprehensive income (loss) before reclassifications, net of tax of $0, $(718), $0, respectively 10,541 (2,687 ) — 7,854 Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $78, $(18), respectively — 1,668 (61 ) 1,607 Net current period other comprehensive income (loss), net of tax of $0, $(640), $(18), respectively 10,541 (1,019 ) (61 ) 9,461 Reclassification of income tax effects from the Tax Reform Act, net of tax of $0, $(691), $(78), respectively (a) — 691 78 769 Reclassification of unrealized gains on equity securities, net of tax of $0, $(902), $0, respectively (b) — (3,125 ) — (3,125 ) Balance at April 1, 2018, net of tax of $0, $(418), $(1,028), respectively $ 26,460 $ (2,091 ) $ 1,512 $ 25,881 (a) In the three months ended April 1, 2018, Teradyne early adopted the ASU 2018-02, “Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” (b) In the three months ended April 1, 2018, Teradyne adopted the ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): For the Three Months ended April 2, 2017 Foreign Currency Translation Adjustments Unrealized Gains (Losses) on Marketable Securities Retirement Plans Prior Service Credit Total (in thousands) Three Months Ended April 2, 2017 Balance at December 31, 2016, net of tax of $0, $209, $(778), respectively $ (21,921 ) $ (60 ) $ 1,767 $ (20,214 ) Other comprehensive income before reclassifications, net of tax of $0, $420,$0, respectively 8,963 513 — 9,476 Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(64), $(38), respectively — (95 ) (68 ) (163 ) Net current period other comprehensive income (loss), net of tax of $0, $356, $(38), respectively 8,963 418 (68 ) 9,313 Balance as April 2, 2017, net of tax of $0, $565, $(816), respectively $ (12,958 ) $ 358 $ 1,699 $ (10,901 )
Reclassifications Out of Accumulated Other Comprehensive Income (Loss) to Statements of Operations	Reclassifications out of accumulated other comprehensive income (loss) to the statement of operations for the three months ended April 1, 2018 and April 2, 2017 were as follows: Details about Accumulated Other Comprehensive (Loss) Income Components For the Three Months Ended Affected Line Item in the Statements of Operations April 1, April 2, (in thousands) Available-for-sale Unrealized (losses) gains, net of tax of $(78), $64, respectively $ (1,668 ) $ 95 Interest (expense) Defined benefit pension and postretirement plans: Amortization of prior service credit, net of tax of $18, $38, respectively 61 68 (a) Total reclassifications, net of tax of $(60), $102, respectively $ (1,607 ) $ 163 Net income (a) The amortization of prior service credit is included in the computation of net periodic pension cost and postretirement benefit; see Note P: “Retirement Plans.”

Goodwill and Acquired Intangi39

Goodwill and Acquired Intangible Assets (Tables)	3 Months Ended
	Apr. 01, 2018
Changes in Carrying Amount of Goodwill by Segment	The changes in the carrying amount of goodwill by reportable segments for the three months ended April 1, 2018, were as follows: Wireless Test Industrial Automation System Test Semiconductor Test Total (in thousands) Balance at December 31, 2017 Goodwill $ 361,819 $ 233,519 $ 158,699 $ 260,540 $ 1,014,577 Accumulated impairment losses (353,843 ) — (148,183 ) (260,540 ) (762,566 ) 7,976 233,519 10,516 — 252,011 Energid acquisition — 15,654 — — 15,654 Foreign currency translation adjustment — 8,035 — — 8,035 Balance at April 1, 2018 Goodwill 361,819 257,208 158,699 260,540 1,038,266 Accumulated impairment losses (353,843 ) — (148,183 ) (260,540 ) (762,566 ) $ 7,976 $ 257,208 $ 10,516 $ — $ 275,700
Schedule of Estimated Intangible Asset Amortization Expense	Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2018 (remainder) 24,236 2019 28,316 2020 13,171 2021 5,298 2022 4,493 Thereafter 8,899
Wireless Test
Schedule of Amortizable Intangible Assets	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet: April 1, 2018 Gross Carrying Amount (1) Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 276,417 $ (231,266 ) $ 3,214 $ 48,365 Customer relationships 96,771 (84,940 ) 340 12,171 Tradenames and trademarks 51,120 (28,108 ) 825 23,837 Non-compete 320 (280 ) — 40 Total intangible assets $ 424,628 $ (344,594 ) $ 4,379 $ 84,413 December 31, 2017 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 270,877 $ (226,190 ) $ 1,618 $ 46,305 Customer relationships 92,741 (83,585 ) 171 9,327 Tradenames and trademarks 50,100 (27,120 ) 416 23,396 Non-compete 320 (260 ) — 60 Total intangible assets $ 414,038 $ (337,155 ) $ 2,205 $ 79,088 (1) Gross carrying amount includes $10.9 million of Energid acquired intangible assets.

Net Income per Common Share (Ta

Net Income per Common Share (Tables)	3 Months Ended
	Apr. 01, 2018
Computation of Basic and Diluted Net Income Per Common Share	The following table sets forth the computation of basic and diluted net income per common share: For the Three Months Ended April 1, 2018 April 2, 2017 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 86,974 $ 85,221 Weighted average common shares-basic 195,255 200,005 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) 4,398 — Convertible note hedge warrant shares (2) 1,830 — Restricted stock units 1,666 1,533 Stock options 321 390 Employee stock purchase plan 14 8 Dilutive potential common shares 8,229 1,931 Weighted average common shares-diluted 203,484 201,936 Net income per common share-basic $ 0.45 $ 0.43 Net income per common share-diluted $ 0.43 $ 0.42 (1) Incremental shares from 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 $31.80, multiplied by 14.5 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 $39.91, multiplied by 14.5 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.

Retirement Plans (Tables)

Retirement Plans (Tables)	3 Months Ended
	Apr. 01, 2018
Defined Benefit Pension Plans
Net Periodic Pension and Postretirement benefit Cost (Income)	For the three months ended April 1, 2018 and April 2, 2017, Teradyne’s net periodic pension cost was comprised of the following: For the Three Months Ended April 1, 2018 April 2, 2017 United States Foreign United States Foreign (in thousands) Service cost $ 571 $ 213 $ 560 $ 185 Interest cost 2,997 186 3,312 163 Expected return on plan assets (3,369 ) (5 ) (3,000 ) (6 ) Amortization of prior service cost 14 — 18 — Total net periodic pension cost $ 213 $ 394 $ 890 $ 342
Postretirement Benefit Plans
Net Periodic Pension and Postretirement benefit Cost (Income)	For the three months ended April 1, 2018 and April 2, 2017, Teradyne’s net periodic postretirement benefit cost (income) was comprised of the following: For the Three Ended April 1, April 2, (in thousands) Service cost $ 9 $ 10 Interest cost 50 50 Amortization of prior service credit (93 ) (124 ) Special termination benefits 1,626 — Total net periodic postretirement benefit cost (income) $ 1,592 $ (64 )

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Apr. 01, 2018
Segment Information	Segment information for the three months ended April 1, 2018 and April 2, 2017 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate and Other Consolidated (in thousands) Three Months Ended April 1, 2018 Revenues $ 373,328 $ 43,019 $ 48,834 $ 22,507 $ (221 ) $ 487,467 Income before income taxes (1)(2) 88,079 5,888 784 464 605 95,820 Total assets (3) 758,737 90,785 406,557 59,739 1,679,375 2,995,193 Three Months Ended April 2, 2017 Revenues $ 355,528 $ 39,845 $ 36,272 $ 25,268 $ — $ 456,913 Income (loss) before income taxes (1)(2) 97,966 (2,759 ) (2,571 ) 1,532 (2,152 ) 92,016 Total assets (3) 740,334 106,754 331,016 61,356 1,602,820 2,842,280 (1) Included in Corporate and Other are: contingent consideration adjustments, severance charges, interest income, interest expense, net foreign exchange gains (losses), and acquisitions related charges. (2) Included in the income (loss) before income taxes for each of the segments are charges and credits related to restructuring and other and inventory 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.
Wireless Test
Schedule of Segment Reporting Information by Segment Charges	Included in the Wireless Test segment are charges in the following line items in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Cost of revenues—inventory charge $ 836 $ 522 Restructuring and other—employee severance — 1,313
Semiconductor Test
Schedule of Segment Reporting Information by Segment Charges	Included in the Semiconductor Test segment are charges and credits in the following line items in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Restructuring and other—employee severance $ 3,761 $ (265 ) Cost of revenues—inventory charge 2,166 1,319
System Test
Schedule of Segment Reporting Information by Segment Charges	Included in the System Test segment are charges in the following line item in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Cost of revenues—inventory charge $ 320 $ 885
Industrial Automation
Schedule of Segment Reporting Information by Segment Charges	Included in the Industrial Automation segment are charges in the following line item in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Cost of revenues—inventory charge $ 200 $ — Restructuring and other—employee severance 120 624
Corporate and Other
Schedule of Segment Reporting Information by Segment Charges	Included in Corporate and Other are charges and credits in the following line items in the statements of operations: For the Three Months Ended April 1, April 2, (in thousands) Restructuring and other—Universal Robots contingent consideration adjustment $ (4,968 ) $ 634 Restructuring and other—acquisition related expense 774 — Restructuring and other—employee severance — 205

Accounting Policies - Additiona

Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 01, 2018	Apr. 01, 2018	Apr. 02, 2017
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized in accordance with ASC 606		$ 487,467	$ 456,913
Revenue on leases		$ 4,300
Standard warranty period		12 months
Deferred revenue and customer advances balance	$ 21,800
ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized in accordance with ASC 606		$ 483,200
ASU 2017-07
Summary Of Significant Accounting Policies [Line Items]
Increase in income from operations			$ 400
Retained Earnings | ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) in adoption of new accounting guidance amount	12,700
Retained Earnings | ASU 2016-01
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) in adoption of new accounting guidance amount	3,100
Accumulated Other Comprehensive Income (Loss) | ASU 2016-01
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) in adoption of new accounting guidance amount	$ (3,100)

Disaggregated Revenue by Primar

Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 01, 2018	Apr. 02, 2017
Disaggregation of Revenue [Line Items]
Total		$ 487,467	$ 456,913
Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		373,328	355,528
System Test
Disaggregation of Revenue [Line Items]
Total		43,019	39,845
Industrial Automation
Disaggregation of Revenue [Line Items]
Total		48,834	36,272
Wireless Test
Disaggregation of Revenue [Line Items]
Total		22,507	$ 25,268
Corporate and Other
Disaggregation of Revenue [Line Items]
Total		(221)
Americas | Point in Time
Disaggregation of Revenue [Line Items]
Total		45,229
Americas | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total		14,373
Americas | Point in Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total		4,979
Americas | Point in Time | Corporate and Other
Disaggregation of Revenue [Line Items]
Total		(221)
Americas | Over Time
Disaggregation of Revenue [Line Items]
Total		16,633
Americas | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total		89
Americas | Over Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total		112
Europe, Middle East and Africa | Point in Time
Disaggregation of Revenue [Line Items]
Total		41,412
Europe, Middle East and Africa | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total		22,573
Europe, Middle East and Africa | Point in Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total		1,041
Europe, Middle East and Africa | Over Time
Disaggregation of Revenue [Line Items]
Total		7,963
Europe, Middle East and Africa | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total		143
Europe, Middle East and Africa | Over Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total		227
Asia Pacific
Disaggregation of Revenue [Line Items]
Total		4,269
Asia Pacific | Wireless Test
Disaggregation of Revenue [Line Items]
Total		188
Asia Pacific | Point in Time
Disaggregation of Revenue [Line Items]
Total		328,455
Asia Pacific | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total		11,583
Asia Pacific | Point in Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total		13,664
Asia Pacific | Over Time
Disaggregation of Revenue [Line Items]
Total		43,506
Asia Pacific | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total		73
Asia Pacific | Over Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total		2,296
SOC | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	300,766
SOC | Americas | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	9,600
SOC | Americas | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	8,791
SOC | Europe, Middle East and Africa | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	12,125
SOC | Europe, Middle East and Africa | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	5,214
SOC | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	3,847
SOC | Asia Pacific | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	224,851
SOC | Asia Pacific | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	36,338
Memory | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		72,562
Memory | Americas | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		2,862
Memory | Americas | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		696
Memory | Europe, Middle East and Africa | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		139
Memory | Europe, Middle East and Africa | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		269
Memory | Asia Pacific | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		66,273
Memory | Asia Pacific | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		2,323
Defense/Aerospace | System Test
Disaggregation of Revenue [Line Items]
Total		20,142
Defense/Aerospace | Americas | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		11,597
Defense/Aerospace | Americas | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		6,188
Defense/Aerospace | Europe, Middle East and Africa | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		1,497
Defense/Aerospace | Europe, Middle East and Africa | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		551
Defense/Aerospace | Asia Pacific | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		101
Defense/Aerospace | Asia Pacific | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		208
Storage Test | System Test
Disaggregation of Revenue [Line Items]
Total		11,934
Storage Test | Americas | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		279
Storage Test | Asia Pacific | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		10,122
Storage Test | Asia Pacific | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		1,533
Production Board Test | System Test
Disaggregation of Revenue [Line Items]
Total		10,943
Production Board Test | Americas | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		1,760
Production Board Test | Americas | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		757
Production Board Test | Europe, Middle East and Africa | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		4,037
Production Board Test | Europe, Middle East and Africa | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		1,559
Production Board Test | Asia Pacific | System Test
Disaggregation of Revenue [Line Items]
Total		234
Production Board Test | Asia Pacific | Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total		1,861
Production Board Test | Asia Pacific | Over Time | System Test
Disaggregation of Revenue [Line Items]
Total		$ 735
[1]	System on a chip ("SOC")

Information about Contract Liab

Information about Contract Liabilities (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue and customer advances	$ 85,892		$ 83,614
Long-term deferred revenue and customer advances	21,726		$ 30,127
ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue and customer advances	90,882	$ 76,638
Long-term deferred revenue and customer advances	30,904	20,848
ASU 2014-09 | Adjustments to Recognize under Legacy GAAP
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue and customer advances	4,990	9,254
Long-term deferred revenue and customer advances	$ 9,178	$ 878

Summarize Impact of ASC 606 to

Summarize Impact of ASC 606 to Condensed consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Jan. 01, 2018	Dec. 31, 2017
ASSETS
Accounts receivable, less allowance for doubtful accounts	$ 413,978		$ 272,783
Inventories, net	131,857		107,525
Deferred tax assets	77,705		84,026
LIABILITIES
Deferred revenue and customer advances	85,892		83,614
Income taxes payable	34,828		59,055
Long-term deferred revenue and customer advances	21,726		30,127
SHAREHOLDERS' EQUITY
Retained earnings	216,120		$ 272,013
ASU 2014-09
ASSETS
Accounts receivable, less allowance for doubtful accounts	346,250
Inventories, net	159,606
Deferred tax assets	80,628
LIABILITIES
Deferred revenue and customer advances	90,882	$ 76,638
Income taxes payable	29,661
Long-term deferred revenue and customer advances	30,904	20,848
SHAREHOLDERS' EQUITY
Retained earnings	170,063
ASU 2014-09 | Adjustments to Recognize under Legacy GAAP
ASSETS
Accounts receivable, less allowance for doubtful accounts	(67,728)
Inventories, net	27,749
Deferred tax assets	2,923
LIABILITIES
Deferred revenue and customer advances	4,990	9,254
Income taxes payable	(5,167)
Long-term deferred revenue and customer advances	9,178	$ 878
SHAREHOLDERS' EQUITY
Retained earnings	$ (46,057)

Summarize Impact of ASC 606 t47

Summarize Impact of ASC 606 to Condensed Consolidated Statement of Operation (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 487,467	$ 456,913
Total cost of revenues	217,635	191,897
Income tax provision	8,846	6,795
Net income	$ 86,974	$ 85,221
Net income per common share:
Basic	$ 0.45	$ 0.43
Diluted	$ 0.43	$ 0.42
ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 483,200
ASU 2014-09 | Adjustments to Recognize under Legacy GAAP
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	(65,642)
Total cost of revenues	(27,749)
Income tax provision	(4,515)
Net income	$ (33,378)
Net income per common share:
Basic	$ (0.17)
Diluted	$ (0.16)
ASU 2014-09 | Legacy GAAP
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 421,825
Total cost of revenues	189,886
Income tax provision	4,331
Net income	$ 53,596
Net income per common share:
Basic	$ 0.27
Diluted	$ 0.26

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands	Feb. 26, 2018	Apr. 01, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 275,700	$ 252,011
Energid Technologies Corporation
Business Acquisition [Line Items]
Total preliminary purchase price	$ 27,600
Goodwill	15,700
Acquired value of intangible assets	$ 10,900
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 1 month 6 days
Net tangible assets	$ 1,000

Composition of Inventories, Net

Composition of Inventories, Net (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Inventory [Line Items]
Raw material	$ 74,762	$ 62,668
Work-in-process	21,256	19,464
Finished Goods	35,839	25,393
Inventories, net	$ 131,857	$ 107,525

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Apr. 01, 2018	Dec. 31, 2017
Inventory [Line Items]
Inventory reserves	$ 103.4	$ 102.9

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Apr. 01, 2018	Apr. 02, 2017	Dec. 31, 2017
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized loss	$ 1,500,000	$ 200,000
Available-for-sale securities, realized gain	300,000	$ 300,000
Available-for-sale marketable securities, Fair Market Value of Investments in debt securities with Unrealized Losses	890,956,000		$ 1,350,896,000
Fair market value of investments with unrealized losses greater than one year	62,100,000		141,000,000
Aggregate loss of investments with unrealized losses greater than one year	1,600,000		1,200,000
Fair market value of investments with unrealized losses less than one year	828,900,000		1,209,900,000
Aggregate loss of investments with unrealized losses less than one year	1,900,000		2,200,000
Debt Mutual Funds
Financial Instruments and Fair Value [Line Items]
Available-for-sale marketable securities, Fair Market Value of Investments in debt securities with Unrealized Losses	1,679,000
Available for sale securities with out contractual maturity date	2,700,000
Universal Robots
Financial Instruments and Fair Value [Line Items]
Maximum payment per earn-out	25,000,000
Foreign Exchange Contracts
Financial Instruments and Fair Value [Line Items]
Notional amount of foreign currency forward contracts	$ 108,800,000		$ 116,800,000

Schedule of Fair Value of Finan

Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	$ 927,172	$ 1,473,905
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	611,946	855,795
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	252,158	282,840
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	44,218	133,186
Equity and Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities		23,430
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	10,726	10,726
Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	4,824	167,342
Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	2,741
Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	559	586
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,587,658	1,903,748
Derivative assets	12	389
Total	1,587,670	1,904,137
Contingent consideration	15,581	45,102
Derivative liabilities	224	446
Total	15,805	45,548
Fair Value, Measurements, Recurring | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	155,543	197,955
Fair Value, Measurements, Recurring | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	482,330	231,888
Fair Value, Measurements, Recurring | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	611,946
Available for sale securities		855,795
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	252,158
Available for sale securities		282,840
Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	44,218
Available for sale securities		133,186
Fair Value, Measurements, Recurring | Equity and Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities		23,430
Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	10,726
Available for sale securities		10,726
Fair Value, Measurements, Recurring | Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	4,824
Available for sale securities		167,342
Fair Value, Measurements, Recurring | Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	2,741
Fair Value, Measurements, Recurring | Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	559
Available for sale securities		586
Fair Value, Measurements, Recurring | Equity Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale equity securities	22,613
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	487,607	427,720
Total	487,607	427,720
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	155,543	197,955
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	306,710	206,335
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		23,430
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale debt securities	2,741
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Equity Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale equity securities	22,613
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,100,051	1,476,028
Derivative assets	12	389
Total	1,100,063	1,476,417
Derivative liabilities	224	446
Total	224	446
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	175,620	25,553
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 debt securities	611,946
Available for sale securities		855,795
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 debt securities	252,158
Available for sale securities		282,840
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 debt securities	44,218
Available for sale securities		133,186
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 debt securities	10,726
Available for sale securities		10,726
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 debt securities	4,824
Available for sale securities		167,342
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 debt securities	559
Available for sale securities		586
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration	15,581	45,102
Total	$ 15,581	$ 45,102

Schedule of Reported Financial

Schedule of Reported Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,587,670	$ 1,904,137
Liabilities	15,805	45,548
Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	224	446
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	637,873	429,843
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	860,526	1,347,979
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	89,259	125,926
Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	12	389
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	15,581	24,497
Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		20,605
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	487,607	427,720
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	462,253	404,290
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	25,354	23,430
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	1,100,063	1,476,417
Liabilities	224	446
Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	224	446
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	175,620	25,553
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	860,526	1,347,979
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	63,905	102,496
Significant Other Observable Inputs (Level 2) | Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	12	389
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	15,581	45,102
Significant Unobservable Inputs (Level 3) | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	$ 15,581	24,497
Significant Unobservable Inputs (Level 3) | Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		$ 20,605

Schedule of Changes in Fair Val

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 01, 2018	Apr. 02, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period		$ 45,102	$ 38,332
Payments	[1]	(24,553)	(1,050)
Fair value adjustment	[2]	(4,968)	634
Balance at end of period		$ 15,581	$ 37,916
[1]	In the three months ended April 1, 2018, Teradyne paid $24.6 million of contingent consideration for the earn-out in connection with the acquisition of Universal Robots A/S ("Universal Robots"). In the three months ended April 2, 2017, Teradyne paid $1.1 million of contingent consideration for the earn-out in connection with the acquisition of Avionics Interface Technology, LLC ("AIT").
[2]	In the three months ended April 1, 2018, the fair value of contingent consideration for the earn-out in connection with the acquisition of Universal Robots was decreased by $5.0 million, primarily due to a decrease in forecasted revenue. In the three months ended April 2, 2017, the fair value of contingent consideration for the earn-out in connection with the acquisition of Universal Robots was increased by $0.6 million primarily due to an increase in forecasted revenue and a decrease in the discount rate.

Schedule of Changes in Fair V55

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration	$ 13,571	$ 1,050
Increase (decrease) in contingent consideration	(4,968)	634
Universal Robots
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration	24,600
Increase (decrease) in contingent consideration	$ (5,000)	600
Avionics Interface Technologies, LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration		$ 1,100

Quantitative Information Associ

Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail) - Monte Carlo Simulation - Universal Robots $ in Thousands	3 Months Ended
	Apr. 01, 2018USD ($)
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration	$ 15,581
Revenue for the period July 1, 2015-December 31, 2018
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Target achievement, volatility	13.00%
Discount Rate	3.80%

Schedule of Carrying Amounts an

Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands		Apr. 01, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Marketable securities		$ 927,172	$ 1,473,905
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		637,873	429,843
Marketable securities		949,785	1,473,905
Derivative assets		12	389
Contingent consideration		15,581	45,102
Derivative liabilities		224	446
Convertible debt	[1]	369,421	365,987
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		637,873	429,843
Marketable securities		949,785	1,473,905
Derivative assets		12	389
Contingent consideration		15,581	45,102
Derivative liabilities		224	446
Convertible debt	[1]	$ 700,626	$ 659,525
[1]	The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion features.

Schedule of Available for Sale

Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 929,385	$ 1,470,729
Available-for-sale marketable securities, Unrealized Gain	1,240	6,582
Available-for-sale marketable securities, Unrealized (Loss)	(3,453)	(3,406)
Available-for-sale marketable securities, Fair Market Value	927,172	1,473,905
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	890,956	1,350,896
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	614,365	858,258
Available-for-sale marketable securities, Unrealized Gain	19	72
Available-for-sale marketable securities, Unrealized (Loss)	(2,438)	(2,535)
Available-for-sale marketable securities, Fair Market Value	611,946	855,795
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	610,938	850,163
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	252,579	283,009
Available-for-sale marketable securities, Unrealized Gain	17	18
Available-for-sale marketable securities, Unrealized (Loss)	(438)	(187)
Available-for-sale marketable securities, Fair Market Value	252,158	282,840
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	249,871	258,933
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	43,472	131,179
Available-for-sale marketable securities, Unrealized Gain	1,200	2,380
Available-for-sale marketable securities, Unrealized (Loss)	(454)	(373)
Available-for-sale marketable securities, Fair Market Value	44,218	133,186
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	17,742	91,010
Equity and Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost		19,403
Available-for-sale marketable securities, Unrealized Gain		4,102
Available-for-sale marketable securities, Unrealized (Loss)		(75)
Available-for-sale marketable securities, Fair Market Value		23,430
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses		1,723
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	10,791	10,775
Available-for-sale marketable securities, Unrealized (Loss)	(65)	(49)
Available-for-sale marketable securities, Fair Market Value	10,726	10,726
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	10,726	10,726
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	4,820	167,523
Available-for-sale marketable securities, Unrealized Gain	4	6
Available-for-sale marketable securities, Unrealized (Loss)		(187)
Available-for-sale marketable securities, Fair Market Value	4,824	167,342
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses		138,340
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	559	582
Available-for-sale marketable securities, Unrealized Gain		4
Available-for-sale marketable securities, Fair Market Value	559	$ 586
Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	2,799
Available-for-sale marketable securities, Unrealized (Loss)	(58)
Available-for-sale marketable securities, Fair Market Value	2,741
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 1,679

Schedule of Reported Available

Schedule of Reported Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 929,385	$ 1,470,729
Available-for-sale marketable securities, Unrealized Gain	1,240	6,582
Available-for-sale marketable securities, Unrealized (Loss)	(3,453)	(3,406)
Available-for-sale marketable securities, Fair Market Value	927,172	1,473,905
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	890,956	1,350,896
Marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	861,794	1,349,970
Available-for-sale marketable securities, Unrealized Gain	54	38
Available-for-sale marketable securities, Unrealized (Loss)	(1,322)	(2,029)
Available-for-sale marketable securities, Fair Market Value	860,526	1,347,979
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	847,446	1,288,844
Long-term marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	67,591	120,759
Available-for-sale marketable securities, Unrealized Gain	1,186	6,544
Available-for-sale marketable securities, Unrealized (Loss)	(2,131)	(1,377)
Available-for-sale marketable securities, Fair Market Value	66,646	125,926
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 43,510	$ 62,052

Contractual Maturities of Inves

Contractual Maturities of Investments in Debt Securities Held (Detail) $ in Thousands	Apr. 01, 2018USD ($)
Schedule of Available-for-sale Securities
Due within one year, cost	$ 861,794
Due after 1 year through 5 years, cost	10,173
Due after 5 years through 10 years, cost	14,583
Due after 10 years, cost	40,036
Total, cost	926,586
Due within one year, fair market value	860,526
Due after 1 year through 5 years, fair market value	10,058
Due after 5 years through 10 years, fair market value	13,823
Due after 10 years, fair maket value	40,024
Total, fair market value	$ 924,431

Schedule of Derivative Instrume

Schedule of Derivative Instruments in Statement of Financial Position at Fair Value (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net	$ (212)	$ (57)
Not Designated as Hedging Instrument | Foreign currency forward contracts | Prepayments
Derivatives, Fair Value [Line Items]
Derivative assets	12	389
Not Designated as Hedging Instrument | Foreign currency forward contracts | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (224)	$ (446)

Schedule of Effect of Derivativ

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
(Gains) losses on derivatives recognized in statements of operations	$ 1,575	$ 1,011

Schedule of Effect of Derivat63

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gains on foreign currency transactions	$ 0.6	$ 1.5

Debt - Additional Information (

Debt - Additional Information (Detail) $ / shares in Units, shares in Millions	Dec. 12, 2016USD ($)d	Apr. 27, 2015USD ($)	Apr. 01, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / shares
Debt Instrument
Term of loan, years		5 years
Pledge percentage of capital stock		65.00%
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Aggregate principal amount	$ 460,000,000		$ 460,000,000	$ 460,000,000
Debt instrument, interest rate, stated percentage	1.25%
Senior notes maturity date	Dec. 15, 2023
Debt instrument, frequency of periodic payment	Payable semi-annually in arrears on June 15 and December 15 of each year
Debt instrument, date of first required payment	Jun. 15, 2017
Debt instrument, conversion option expiration date	Sep. 15, 2023
Debt instrument conversion price | $ / shares			$ 31.80	$ 31.80
Shares that would be issued upon conversion | shares			14.5
Strike price per share of warrant | $ / shares				$ 39.91
Payment for net cost of convertible note hedges net of warrant proceeds			$ 33,000,000
Debt instrument, effective annual interest rate			5.00%
Financing cost	$ 7,200,000		$ 6,000,000
Debt issuance costs, amortization period			7 years
Unamortized discount			$ 90,600,000
Debt Instrument, convertible, remaining discount amortization period			5 years 9 months 18 days
Debt instrument, convertible, carrying amount of equity component			$ 100,800,000
Value of notes converted			661,200,000
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option one
Debt Instrument
Trading days measurement period | d	20
Consecutive trading days measurement period | d	30
Percentage of conversion price	130.00%
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option two
Debt Instrument
Trading days measurement period | d	5
Consecutive trading days measurement period | d	5
Percentage of closing sale price of common stock and conversion rate product	98.00%
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

Components of Convertible Senio

Components of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017	Dec. 12, 2016
Debt Instrument
Net Carrying amount of convertible debt	$ 369,421	$ 365,987
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Debt Principal	460,000	460,000	$ 460,000
Unamortized discount	90,579	94,013
Net Carrying amount of convertible debt	$ 369,421	$ 365,987

Interest Expense on Convertible

Interest Expense on Convertible Senior Notes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Debt Instrument
Contractual interest expense on the coupon	$ 1,438	$ 1,438
Amortization of the discount component and debt issue fees recognized as interest expense	3,434	3,268
Total interest expense on the convertible debt	$ 4,872	$ 4,706

Schedule of Prepayments (Detail

Schedule of Prepayments (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Prepaid And Other Current Assets [Line Items]
Contract manufacturer and supplier prepayments	$ 76,204	$ 82,503
Prepaid maintenance and other services	8,449	8,189
Prepaid taxes	9,938	5,039
Other prepayments	11,964	12,386
Total prepayments	$ 106,555	$ 108,117

Deferred Revenue and Customer68

Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	Apr. 01, 2018	Jan. 01, 2018	Dec. 31, 2017	Apr. 02, 2017	Dec. 31, 2016
Deferred Revenue Arrangement
Maintenance and training	$ 59,365		$ 57,256
Extended warranty	24,590	$ 24,438	24,438	$ 24,969	$ 28,200
Customer advances, undelivered elements and other	23,663		32,047
Total deferred revenue and customer advances	$ 107,618		$ 113,741

Warranty Accrual Included in Ot

Warranty Accrual Included in Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 8,200	$ 7,203
Accruals for warranties issued during the period	3,063	3,021
Adjustments related to pre-existing warranties	(139)	(471)
Settlements made during the period	(3,576)	(2,699)
Balance at end of period	$ 7,548	$ 7,054

Extended Product Warranty of Sh

Extended Product Warranty of Short and Long-Term Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 24,438	$ 28,200
Deferral of new extended warranty revenue	5,139	4,048
Recognition of extended warranty deferred revenue	(4,987)	(7,279)
Balance at end of period	$ 24,590	$ 24,969

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - $ / shares shares in Millions	1 Months Ended			3 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2014	Apr. 01, 2018	Apr. 02, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Stock options term				7 years
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
Stock options term				7 years
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				0.1	0.1
Weighted average grant date fair value of restricted stock units granted				$ 54.85	$ 35.66
Estimated annual dividend amount per share				0.36	0.28
Stock price				$ 47.70	$ 28.56
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%
PBIT Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Total shareholder return performance measurement period	3 years
Restricted stock unit awards granted				0.1	0.1
Weighted average grant date fair value of restricted stock units granted				$ 46.62	$ 27.72
PBIT 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%
PBIT 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%
Service-Based Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted				0.5	0.8
Weighted average grant date fair value of restricted stock units granted				$ 46.58	$ 27.86
Service-Based Restricted Stock Units | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted				0.1	0.1
Weighted average grant date fair value of restricted stock units granted				$ 12.17	$ 7.13

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	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rate	2.20%	1.50%
Expected historical volatility	26.80%	26.60%
Dividend yield	0.80%	1.00%
New York Stock Exchange Composite Index
Share-based Compensation Arrangement by Share-based Payment Award
Expected historical volatility	12.40%	13.40%

Schedule of Estimated Fair Va73

Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail) - Stock Options	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Expected life (years)	5 years	5 years
Risk-free interest rate	2.40%	2.00%
Volatility-historical	26.40%	27.80%
Dividend yield	0.80%	1.00%

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	$ 7,854	$ 9,476
Amounts reclassified from accumulated other comprehensive income, net of tax	1,607	(163)
Other comprehensive income (loss)	9,461	9,313
Reclassification of income tax effects from the Tax Reform Act, net of tax	769
Reclassification of unrealized gains on equity securities, net of tax	1,668	(95)
Balance	1,904,983
ASU 2016-01
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax	(3,125)
Foreign Currency Translation Reclassification Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	15,919	(21,921)
Other comprehensive income (loss) before reclassifications, net of tax	10,541	8,963
Other comprehensive income (loss)	10,541	8,963
Balance	26,460	(12,958)
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	1,362	(60)
Other comprehensive income (loss) before reclassifications, net of tax	(2,687)	513
Amounts reclassified from accumulated other comprehensive income, net of tax	1,668	(95)
Other comprehensive income (loss)	(1,019)	418
Reclassification of income tax effects from the Tax Reform Act, net of tax	691
Balance	(2,091)	358
Unrealized Gains (Losses) on Marketable Securities | ASU 2016-01
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax	(3,125)
Amortization of Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	1,495	1,767
Amounts reclassified from accumulated other comprehensive income, net of tax	(61)	(68)
Other comprehensive income (loss)	(61)	(68)
Reclassification of income tax effects from the Tax Reform Act, net of tax	78
Balance	1,512	1,699
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	18,776	(20,214)
Amounts reclassified from accumulated other comprehensive income, net of tax	1,607	(163)
Balance	$ 25,881	$ (10,901)

Changes in Accumulated Other 75

Changes in Accumulated Other Comprehensive Income (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income, tax	$ 60	$ (102)
Foreign currency translation adjustments, tax	0	0	$ 0	$ 0
Unrealized gains on marketable securities, tax	(418)	565	1,815	209
Retirement plans prior service benefit, tax	(1,028)	(816)	$ (932)	$ (778)
Reclassification of unrealized gains on equity securities, net of tax	(78)	64
Foreign Currency Translation Reclassification Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, tax	0	0
Amounts reclassified from accumulated other comprehensive income, tax	0	0
Other comprehensive income (loss), tax	0	0
Reclassification of income tax effects from the Tax Reform Act, net of tax	0
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, tax	(718)	420
Amounts reclassified from accumulated other comprehensive income, tax	78	(64)
Other comprehensive income (loss), tax	(640)	356
Reclassification of income tax effects from the Tax Reform Act, net of tax	(691)
Amortization of Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, tax	0	0
Amounts reclassified from accumulated other comprehensive income, tax	(18)	(38)
Other comprehensive income (loss), tax	(18)	$ (38)
Reclassification of income tax effects from the Tax Reform Act, net of tax	(78)
ASU 2016-01 | Foreign Currency Translation Reclassification Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax	0
ASU 2016-01 | Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax	(902)
ASU 2016-01 | Amortization of Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax	$ 0

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income (Loss) to Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest (expense) income	$ (5,981)	$ (3,520)
Reclassifications, net of tax	(1,607)	163
Unrealized Gains (Losses) on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax	(1,668)	95
Amortization of Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax	61	68
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax	(1,607)	163
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest (expense) income	$ (1,668)	$ 95

Reclassifications Out of Accu77

Reclassifications Out of Accumulated Other Comprehensive Income (Loss) to Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ (60)	$ 102
Unrealized Gains (Losses) on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	(78)	64
Amortization of Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 18	$ 38

Changes in Carrying Amount of G

Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Feb. 26, 2018	Dec. 31, 2017
Goodwill [Line Items]
Foreign currency translation adjustment	$ 8,035
Goodwill	1,038,266		$ 1,014,577
Accumulated impairment losses	(762,566)		(762,566)
Goodwill	275,700		252,011
Energid Technologies Corporation
Goodwill [Line Items]
Energid acquisition	15,654
Goodwill		$ 15,700
Wireless Test
Goodwill [Line Items]
Goodwill	361,819		361,819
Accumulated impairment losses	(353,843)		(353,843)
Goodwill	7,976		7,976
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	8,035
Goodwill	257,208		233,519
Goodwill	257,208		233,519
Industrial Automation | Energid Technologies Corporation
Goodwill [Line Items]
Energid acquisition	15,654
System Test
Goodwill [Line Items]
Goodwill	158,699		158,699
Accumulated impairment losses	(148,183)		(148,183)
Goodwill	10,516		10,516
Semiconductor Test
Goodwill [Line Items]
Goodwill	260,540		260,540
Accumulated impairment losses	$ (260,540)		$ (260,540)

Schedule of Amortizable Intangi

Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Apr. 01, 2018		Dec. 31, 2017
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 424,628	[1]	$ 414,038
Accumulated Amortization	(344,594)		(337,155)
Foreign Currency Translation Adjustment	4,379		2,205
Net Carrying Amount	84,413		79,088
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	276,417	[1]	270,877
Accumulated Amortization	(231,266)		(226,190)
Foreign Currency Translation Adjustment	3,214		1,618
Net Carrying Amount	48,365		46,305
Customer Relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	96,771	[1]	92,741
Accumulated Amortization	(84,940)		(83,585)
Foreign Currency Translation Adjustment	340		171
Net Carrying Amount	12,171		9,327
Trademarks and tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	51,120	[1]	50,100
Accumulated Amortization	(28,108)		(27,120)
Foreign Currency Translation Adjustment	825		416
Net Carrying Amount	23,837		23,396
Non-compete Agreements
Finite-Lived Intangible Assets
Gross Carrying Amount	320	[1]	320
Accumulated Amortization	(280)		(260)
Net Carrying Amount	$ 40		$ 60
[1]	Gross carrying amount includes $10.9 million of Energid acquired intangible assets.

Schedule of Amortizable Intan80

Schedule of Amortizable Intangible Assets (Parenthetical) (Detail) $ in Millions	Feb. 26, 2018USD ($)
Energid Technologies Corporation
Finite-Lived Intangible Assets
Acquired value of intangible assets	$ 10.9

Goodwill and Acquired Intangi81

Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Goodwill and Intangible Assets Disclosure [Line Items]
Acquired intangible assets amortization	$ 7,698	$ 7,952

Schedule of Estimated Intangibl

Schedule of Estimated Intangible Asset Amortization Expense (Detail) $ in Thousands	Apr. 01, 2018USD ($)
Finite-Lived Intangible Assets
2018 (remainder)	$ 24,236
2,019	28,316
2,020	13,171
2,021	5,298
2,022	4,493
Thereafter	$ 8,899

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
		Apr. 01, 2018	Apr. 02, 2017
Net Income Loss Per Common Share
Net income for basic and diluted net income per share		$ 86,974	$ 85,221
Weighted average common shares-basic		195,255	200,005
Incremental shares from assumed conversion of convertible notes	[1]	4,398
Convertible note hedge warrant shares	[2]	1,830
Employee stock purchase plan		14	8
Dilutive potential common shares		8,229	1,931
Weighted average common shares-diluted		203,484	201,936
Net income per common share-basic		$ 0.45	$ 0.43
Net income per common share-diluted		$ 0.43	$ 0.42
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		1,666	1,533
Stock Options
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		321	390
[1]	Incremental shares from 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 $31.80, multiplied by 14.5 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 $39.91, multiplied by 14.5 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.

Computation of Basic and Dilu84

Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail) shares in Millions	3 Months Ended
	Apr. 01, 2018$ / sharesshares
Convertible Notes
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 31.80
Shares that would be issued upon conversion | shares	14.5
Convertible Notes Hedge Warrant
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 39.91
Shares that would be issued upon conversion | shares	14.5

Net Income Per Common Share - A

Net Income Per Common Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Net Income Loss Per Common Share
Exercise of stock options		0.1
Restricted Stock Units
Net Income Loss Per Common Share
Dilutive securities excluded from earning per share	0.4

Restructuring and Other - Addit

Restructuring and Other - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Restructuring Cost and Reserve
Contingent consideration adjustment	$ (4,968)	$ 634
Severance benefit and charges		600
Acquisition charge	800
Restructuring and other benefits		$ 2,500
Lease termination period		2017-09
Wireless Test
Restructuring Cost and Reserve
Lease impairment		$ 1,300
Semiconductor Test
Restructuring Cost and Reserve
Severance benefit and charges	3,900
Universal Robots
Restructuring Cost and Reserve
Contingent consideration adjustment	$ (5,000)	$ 600

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) $ in Millions	3 Months Ended
	Apr. 01, 2018USD ($)
U.S. Supplemental Executive Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans	$ 0.6
Non-United States Subsidiaries
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans	$ 0.2

Schedule of Net Periodic Pensio

Schedule of Net Periodic Pension and Postretirement benefit Cost (Income) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	$ 571	$ 560
Interest cost	2,997	3,312
Expected return on plan assets	(3,369)	(3,000)
Amortization of prior service cost	14	18
Total	213	890
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	213	185
Interest cost	186	163
Expected return on plan assets	(5)	(6)
Total	394	342
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Service cost	9	10
Interest cost	50	50
Amortization of prior service credit	(93)	(124)
Special termination benefits	1,626
Total	$ 1,592	$ (64)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Apr. 01, 2018USD ($)
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments	$ 285.8
Purchase commitments less than one year	$ 275.7

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			12 Months Ended
	Apr. 01, 2018	Dec. 31, 2017	Apr. 02, 2017	Dec. 31, 2017
Income Taxes [Line Items]
Effective tax rate	9.20%		7.40%
U.S. statutory federal tax rate	21.00%			35.00%
Discrete tax benefits	$ 8,300		$ 7,000
Discrete tax benefits, stock based compensation	7,600		5,500
Discrete tax expense	2,300
Expense related to remeasurement of deferred tax assets	1,700
Discrete tax expenses, Other	600
Discrete tax benefits, Other	700		800
Discrete tax benefits, U.S. research and development tax credits			700
Uncertain tax positions	37,300	$ 36,300		$ 36,300
Net Increase in uncertain tax positions	1,000
Accrued interest and penalties	300	300		$ 300
Interest and penalties related to income tax, expense (benefit)	30		(100)
Tax savings due to the tax holiday	$ 3,000		$ 4,700
Tax savings due to the tax holiday, per share	$ 0.01		$ 0.02
Tax holiday expiration date	December 31, 2020
Provisional amount of additional income tax expense		186,000
Transition tax on mandatory deemed repatriation of foreign earnings		161,000
Expense related to remeasurement of deferred tax assets and liabilities		33,600
Benefit associated with impact of correlative adjustments on tax positions		10,300
Expense related to remeasurement of certain deferred		$ 1,700
ASU 2016-09
Income Taxes [Line Items]
Discrete tax benefits, stock based compensation	$ 7,400		$ 5,200

Segment Information - Additiona

Segment Information - Additional Information (Detail)	3 Months Ended
	Apr. 01, 2018Segment
Segment Reporting Information [Line Items]
Operating segments	4

Schedule of Segment Information

Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 01, 2018		Apr. 02, 2017		Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 487,467		$ 456,913
Income (loss) before income taxes	[1],[2]	95,820		92,016
Total assets		2,995,193	[3]	2,842,280	[3]	$ 3,109,545
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		373,328		355,528
Income (loss) before income taxes	[1],[2]	88,079		97,966
Total assets	[3]	758,737		740,334
System Test
Segment Reporting Information [Line Items]
Revenues		43,019		39,845
Income (loss) before income taxes	[1],[2]	5,888		(2,759)
Total assets	[3]	90,785		106,754
Industrial Automation
Segment Reporting Information [Line Items]
Revenues		48,834		36,272
Income (loss) before income taxes	[1],[2]	784		(2,571)
Total assets	[3]	406,557		331,016
Wireless Test
Segment Reporting Information [Line Items]
Revenues		22,507		25,268
Income (loss) before income taxes	[1],[2]	464		1,532
Total assets	[3]	59,739		61,356
Corporate and Other
Segment Reporting Information [Line Items]
Revenues		(221)
Income (loss) before income taxes	[1],[2]	605		(2,152)
Total assets	[3]	$ 1,679,375		$ 1,602,820
[1]	Included in Corporate and Other are: contingent consideration adjustments, severance charges, interest income, interest expense, net foreign exchange gains (losses), and acquisitions related charges.
[2]	Included in the income (loss) before income taxes for each of the segments are charges and credits related to restructuring and other and inventory 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.

Schedule of Segment Reporting I

Schedule of Segment Reporting Information by Segment Charges (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Segment Reporting Information [Line Items]
Acquisition related expense	$ 800
Restructuring and other-employee severance	(313)	$ 2,511
Contingent consideration adjustment	(4,968)	634
Universal Robots
Segment Reporting Information [Line Items]
Contingent consideration adjustment	(5,000)	600
Semiconductor Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge	2,166	1,319
Semiconductor Test | Severance And Benefits
Segment Reporting Information [Line Items]
Restructuring and other-employee severance	3,761	(265)
System Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge	320	885
Industrial Automation
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge	200
Restructuring and other-employee severance	120	624
Wireless Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge	836	522
Restructuring and other-employee severance		1,313
Corporate and Other | Restructuring and other
Segment Reporting Information [Line Items]
Acquisition related expense	774
Restructuring and other-employee severance		205
Corporate and Other | Universal Robots | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment	$ (4,968)	$ 634

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended		12 Months Ended
	Apr. 01, 2018	Apr. 02, 2017	Dec. 31, 2018	Jan. 31, 2018	Jan. 31, 2017	Dec. 31, 2016
Stockholders Equity Note Disclosure [Line Items]
Stock repurchase program, authorized amount						$ 500,000,000
Cumulative repurchases, value	$ 134,300,000	$ 37,700,000
Cumulative repurchases, shares	2.9	1.3
Common stock average price	$ 45.69	$ 29.38
Dividends payable, amount per share				$ 0.09	$ 0.07
Dividend payment	$ 17,588,000	$ 14,021,000
Scenario, Forecast
Stockholders Equity Note Disclosure [Line Items]
Cumulative repurchases, value			$ 750,000,000
Maximum
Stockholders Equity Note Disclosure [Line Items]
Stock repurchase program, authorized amount				$ 1,500,000,000

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) - USD ($) $ in Thousands	Apr. 25, 2018	Apr. 01, 2018
Subsequent Event [Line Items]
Cash acquired in excess of payments to acquire business		$ 25,356
Mobile Industrial Robots ApS ("MiR") | Subsequent Event
Subsequent Event [Line Items]
Cash acquired in excess of payments to acquire business	$ 148,000
Business combination, recognized identifiable assets acquired and liabilities assumed, contingent liability	$ 124,000