Teradyne (TER) 10-K 22 Feb 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 16, 2021	Jun. 26, 2020
Cover [Abstract]
Amendment Flag	false
Document Type	10-K
Document Fiscal Year Focus	2020
Entity Central Index Key	0000097210
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Document Period End Date	Dec. 31, 2020
Entity Registrant Name	TERADYNE, INC
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 10.6
Trading Symbol	TER
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity File Number	001-06462
Entity Incorporation, State or Country Code	MA
Entity Tax Identification Number	04-2272148
Entity Address, Address Line One	600 RIVERPARK DRIVE
Entity Address, City or Town	NORTH READING
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01864
City Area Code	978
Local Phone Number	370-2700
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		166,694,772
ICFR Auditor Attestation Flag	true

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 914,121	$ 773,924
Marketable securities	522,280	137,303
Accounts receivable, less allowance for doubtful accounts of $2,034 and $1,736 in 2020 and 2019, respectively	497,506	362,368
Inventories, net	222,189	196,691
Prepayments and other current assets	259,338	188,598
Total current assets	2,415,434	1,658,884
Property, plant and equipment, net	394,800	320,216
Operating lease right-of-use assets, net	54,569	57,539
Marketable securities	117,980	104,490
Deferred tax assets	87,913	75,185
Retirement plans assets	17,468	18,457
Other assets	9,384	10,332
Acquired intangible assets, net	100,939	125,480
Goodwill	453,859	416,431
Total assets	3,652,346	2,787,014
Current liabilities:
Accounts payable	133,663	126,617
Accrued employees' compensation and withholdings	220,321	163,883
Deferred revenue and customer advances	134,662	104,876
Other accrued liabilities	77,581	70,871
Operating lease liabilities	20,573	19,476
Contingent consideration		9,106
Income taxes payable	80,728	44,200
Current debt	33,343
Total current liabilities	700,871	539,029
Retirement plans liabilities	151,140	134,471
Long-term deferred revenue and customer advances	58,359	45,974
Long-term contingent consideration	7,227	30,599
Deferred tax liabilities	10,821	14,070
Long-term other accrued liabilities	19,352	19,535
Long-term operating lease liabilities	42,073	45,849
Long-term incomes taxes payable	74,930	82,642
Debt	376,768	394,687
Total liabilities	1,441,541	1,306,856
Commitments and contingencies (Note M)
Mezzanine equity:
Convertible common shares	3,787
SHAREHOLDERS' EQUITY
Common stock, $0.125 par value, 1,000,000 shares authorized, 166,123 and 166,410 shares issued and outstanding at December 31, 2020 and 2019, respectively	20,765	20,801
Additional paid-in capital	1,765,323	1,720,129
Accumulated other comprehensive income (loss)	33,516	(18,854)
Retained earnings (accumulated deficit)	387,414	(241,918)
Total shareholders' equity	2,207,018	1,480,158
Total liabilities, convertible common shares and shareholders' equity	$ 3,652,346	$ 2,787,014

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, less allowance for doubtful accounts	$ 2,034	$ 1,736
Common stock, par value	$ 0.125	$ 0.125
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	166,123,000	166,410,000
Common stock, shares outstanding	166,123,000	166,410,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	[1],[2]	$ 3,121,469	$ 2,294,965	$ 2,100,802
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)		1,335,728	955,136	880,408
Gross profit		1,785,741	1,339,829	1,220,394
Operating expenses:
Selling and administrative		464,769	437,084	390,669
Engineering and development		374,964	322,824	301,505
Acquired intangible assets amortization		30,803	40,147	39,191
Restructuring and other		(13,202)	(13,880)	15,232
Total operating expenses		857,334	786,175	746,597
Income from operations		928,407	553,654	473,797
Non-operating (income) expenses:
Interest income		(5,982)	(16,990)	(20,458)
Interest expense		24,182	22,224	21,780
Other (income) expense, net		9,192	22,648	4,674
Income before income taxes		901,015	525,772	467,801
Income tax provision		116,868	58,304	16,022
Net income		$ 784,147	$ 467,468	$ 451,779
Net income per common share:
Basic		$ 4.72	$ 2.74	$ 2.41
Diluted		$ 4.28	$ 2.60	$ 2.35
Weighted average common shares—basic		166,120	170,425	187,672
Weighted average common shares—diluted		183,042	179,459	192,605
Product [Member]
Revenues:
Total revenues		$ 2,690,906	$ 1,887,674	$ 1,729,621
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)		1,157,476	782,047	727,138
Service [Member]
Revenues:
Total revenues		430,563	407,291	371,181
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)		$ 178,252	$ 173,089	$ 153,270
[1]	Includes $10.0 million, $8.4 million and $12.0 million in 2020, 2019 and 2018, respectively, for leases of Teradyne’s systems recognized outside of ASC 606: “Revenue from Contracts with Customers.”
[2]	Revenues attributable to a country are based on location of customer site.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income	$ 784,147	$ 467,468	$ 451,779
Other comprehensive income, net of tax:
Foreign currency translation adjustment, net of tax of $0, $0, $0	48,903	(10,991)	(28,442)
Available-for-sale marketable securities:
Unrealized gains (losses) on marketable securities arising during period, net of tax of $1,629, $1,659, $(722), respectively	5,839	6,015	(2,110)
Less: Reclassification adjustment for (gains) losses included in net income, net of tax of $(665), $(192), $(21), respectively	(2,365)	(690)	1,337
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total	3,474	5,325	(773)
Defined benefit pension and post-retirement plans:
Amortization of prior service benefit included in net periodic pension and post-retirement benefit, net of tax $(2), $(43), $(71), respectively	(7)	(148)	(245)
Other comprehensive income (loss)	52,370	(5,814)	(29,460)
Comprehensive income	$ 836,517	$ 461,654	$ 422,319

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Foreign currency translation adjustments, tax	$ 0	$ 0	$ 0
Unrealized gains (losses) on marketable securities arising during period, net of tax	1,629	1,659	(722)
Reclassification adjustment for (gains) losses included in net income, net of tax	(665)	(192)	(21)
Amortization of prior service credit, net of tax	$ (2)	$ 43	$ 71

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Convertible Common Shares	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit)Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance at Dec. 31, 2017	$ 1,953,646			$ 24,444	$ 1,638,413	$ 18,776	$ 272,013
Balance, Shares at Dec. 31, 2017				195,548
Net issuance of common stock under stock-based plans	129			$ 201	(72)
Net issuance of common stock under stock-based plans (in shares)				1,613
Stock-based compensation expense	33,304				33,304
Repurchase of common stock	(832,356)			$ (2,705)			(829,651)
Repurchase of common stock (in shares)				(21,639)
Cash dividends	(67,367)						(67,367)
Net income	451,779						451,779
Other comprehensive income	(29,460)					(29,460)
Reclassification of unrealized gains on equity securities						(3,125)	3,125
Reclassification of tax effects resulting from the Tax Reform Act						769	(769)
Balance at Dec. 31, 2018	1,522,354		$ 12,679	$ 21,940	1,671,645	(13,040)	(158,191)	$ 12,679
Balance, Shares at Dec. 31, 2018				175,522
Net issuance of common stock under stock-based plans	10,622			$ 223	10,399
Net issuance of common stock under stock-based plans (in shares)				1,784
Stock-based compensation expense	38,085				38,085
Repurchase of common stock	(491,202)			$ (1,362)			(489,840)
Repurchase of common stock (in shares)				(10,896)
Cash dividends	(61,355)						(61,355)
Net income	467,468						467,468
Other comprehensive income	(5,814)					(5,814)
Balance at Dec. 31, 2019	1,480,158			$ 20,801	1,720,129	(18,854)	(241,918)
Balance, Shares at Dec. 31, 2019				166,410
Net issuance of common stock under stock-based plans				$ 154	4,696	4,850
Net issuance of common stock under stock-based plans (in shares)				1,230
Stock-based compensation expense	44,285				44,285
Repurchase of common stock	(88,465)			$ (190)			(88,275)
Repurchase of common stock (in shares)				(1,517)
Cash dividends	(66,540)						(66,540)
Convertible common shares	(3,787)				(3,787)
Convertible common shares (in shares)		3,787
Net income	784,147						784,147
Other comprehensive income	52,370					52,370
Balance at Dec. 31, 2020	$ 2,207,018			$ 20,765	$ 1,765,323	$ 33,516	$ 387,414
Balance, Shares at Dec. 31, 2020		3,787		166,123

CONSOLIDATED STATEMENTS OF SH_2

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock, Dividends, Per Share, Cash Paid	$ 0.10	$ 0.09	$ 0.09

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 784,147	$ 467,468	$ 451,779
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Depreciation	80,119	70,834	67,415
Amortization	46,624	49,821	45,809
Stock-based compensation	44,906	37,897	33,577
Provision for excess and obsolete inventory	17,534	15,244	11,242
Retirement plans actuarial losses (gains)	10,284	8,176	(3,316)
Contingent consideration adjustment	(23,271)	(19,257)	987
Deferred taxes	(15,688)	(9,456)	28,340
(Gains) losses on investments	(7,898)	(6,033)	3,494
Investment impairment		15,000
Other	1,557	766	1,083
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(129,451)	(70,440)	(17,938)
Inventories	(8,438)	(27,408)	(29,498)
Prepayments and other assets	(64,418)	(23,784)	(58,402)
Accounts payable and other accrued expenses	73,167	49,279	13,693
Deferred revenue and customer advances	39,974	39,313	13,379
Retirement plans contributions	(5,382)	(5,086)	(4,334)
Income taxes	25,169	(13,584)	(80,429)
Net cash provided by operating activities	868,935	578,750	476,881
Cash flows from investing activities:
Purchases of property, plant and equipment	(184,977)	(134,642)	(114,379)
Proceeds from government subsidy for property, plant and equipment			7,920
Purchases of marketable securities	(900,196)	(662,701)	(918,744)
Proceeds from maturities of marketable securities	479,678	611,927	1,270,439
Proceeds from sales of marketable securities	35,006	105,586	846,122
Proceeds from life insurance	546	2,912	1,126
Purchase of investment and acquisition of businesses, net of cash acquired	149	(79,742)	(169,474)
Net cash (used for) provided by investing activities	(569,794)	(156,660)	923,010
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	28,527	29,312	20,973
Repurchase of common stock	(88,465)	(500,000)	(823,478)
Dividend payments	(66,482)	(61,305)	(67,322)
Payments related to net settlement of employee stock compensation awards	(23,014)	(14,741)	(20,023)
Payments of contingent consideration	(8,852)	(27,615)	(13,571)
Net cash (used for) provided by financing activities	(158,286)	(574,349)	(903,421)
Effects of exchange rate changes on cash and cash equivalents	(658)	(569)	439
Increase (decrease) in cash and cash equivalents	140,197	(152,828)	496,909
Cash and cash equivalents at beginning of year	773,924	926,752	429,843
Cash and cash equivalents at end of year	914,121	773,924	926,752
Cash paid for:
Interest	6,435	5,996	6,205
Income taxes	106,577	81,410	72,811
Non-cash investing activities:
Capital expenditures incurred but not yet paid:	$ 3,666	$ 4,068	$ 2,537

The Company

The Company	12 Months Ended
	Dec. 31, 2020
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 many industries including consumer electronics, wireless, automotive, industrial, computing, communications, and aerospace and defense industries. Teradyne’s industrial automation products include collaborative robotic arms, autonomous mobile robots, and advanced robotic control software used by global manufacturing, logistics and light industrial customers to improve quality, increase manufacturing and material handling efficiency and decrease manufacturing and logistics costs. Teradyne’s automatic test equipment and industrial automation products and services include: • semiconductor test (“Semiconductor Test”) systems; • storage and system level test (“Storage Test”) systems, defense/aerospace (“Defense/Aerospace”) test instrumentation and systems, and circuit-board test and inspection (“Production Board Test”) systems (collectively these products represent “System Test”); • wireless test (“Wireless Test”) systems; and • industrial automation (“Industrial Automation”) products. On February 26, 2018, Teradyne acquired Energid Technologies Corporation (“Energid”) for a total 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. Energid was merged with Universal Robots which is part of Teradyne’s Industrial Automation segment. On April 25, 2018, Teradyne acquired Mobile Industrial Robots ApS (“MiR”), a Danish limited liability company. MiR is a leading maker of collaborative autonomous mobile robots (“AMRs”) for industrial applications. The total purchase price was approximately $197.8 million, which included cash paid of approximately $145.2 million and $52.6 million in fair value of contingent consideration payable upon achievement of certain thresholds and targets for revenue and earnings before interest and taxes through 2020. Contingent consideration for 2018 was $30.8 million and was paid in March 2019. Contingent consideration for 2019 was $8.9 million and was paid in March 2020. MiR is included in Teradyne’s Industrial Automation segment. On January 30, 2019, Teradyne acquired all of the issued and outstanding shares of Lemsys SA (“Lemsys”) for a total purchase price of approximately $9.1 million. Lemsys strengthens Teradyne’s position in the electrification of vehicles, solar and wind power, and industrial applications. Lemsys is included in Teradyne’s Semiconductor Test segment. On June 3, 2019, Teradyne invested $15.0 million in RealWear, Inc. (“RealWear”). RealWear, a private company, develops and sells advanced wearable technology including industrial, hands-free, head-mounted augmented reality devices that make the workplace safer and more productive. On February 28, 2020, RealWear’s debt holder demanded repayment of its $25.0 million loan to RealWear. As a result, in the fourth quarter of 2019, Teradyne recorded an impairment charge of $15.0 million to reduce its investment in RealWear to zero as of December 31, 2019. On November 13, 2019, Teradyne acquired 100% of the membership interests of AutoGuide, LLC (“AutoGuide”), a maker of high payload AMRs, an emerging and fast growing segment of the global forklift market. The total purchase price was approximately $81.6 million, which included cash paid of approximately $57.6 million and $24.0 million in fair value of contingent consideration payable upon achievement of certain performance targets, extending potentially through 2022. At December 31, 2020, the maximum contingent consideration that could be paid is $100.2 million. AutoGuide’s AMRs are used for material transport of payloads up to 4,500 kg in manufacturing, warehouse and logistics applications. These products complement MiR’s lower payload products. AutoGuide is included in our Industrial Automation segment.

Accounting Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies	B. ACCOUNTING POLICIES The consolidated financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions are eliminated. Certain prior years’ amounts were reclassified to conform to the current year presentation. Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going basis, management evaluates its estimates, including those related to inventories, investments, goodwill, intangible and other long-lived assets, accounts receivable, income taxes, deferred tax assets and liabilities, pensions, warranties, contingent consideration liabilities, and loss contingencies. Management bases its estimates on historical experience and on appropriate and customary assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Due to the COVID-19 pandemic, there has been uncertainty and disruption in the global economy and our markets. Management is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of February 22, 2021, the date of issuance of this Annual Report on Form 10-K. These estimates may change, as new events occur and additional information is obtained. Actual results may differ significantly from these estimates under different assumptions or conditions. Revenue Recognition Revenue from Contracts with Customers Teradyne adopted Accounting Standard Codification (“ASC”) 606 “Revenue from Contracts with Customers” on January 1, 2018 using the modified retrospective method for all contracts not completed as of the date of adoption. 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. • 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. • Teradyne periodically enters into contracts with customers in which a customer may purchase a combination of goods and 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. • 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. • 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. • 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 that 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. Performance Obligations Products Teradyne products consist 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, wireless test systems and industrial automation products. Teradyne’s hardware is recognized at a point in time upon transfer of control to the customer. Services Teradyne services consist of extended warranties, training and application support, service agreements, post contract customer support (“PCS”) and replacement parts. Each service is recognized based on relative standalone selling price. Extended warranty, training and support, service agreements and PCS are recognized over time based on the period of service. Replacement parts are recognized at a point in time upon transfer of control to the customer. Teradyne does not allow customer returns or provide refunds to customers for any products or services. Teradyne products include 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. Cost related to warranty are included in cost of revenues when product revenues are recognized. As of December 31, 2020 and 2019, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2020 2019 (in thousands) Maintenance, service and training $ 77,654 $ 63,815 Customer advances, undelivered elements and other 63,438 56,358 Extended warranty 51,929 30,677 Total deferred revenue and customer advances $ 193,021 $ 150,850 Product Warranty Teradyne generally provides a one-year warranty on its products, commencing upon installation, acceptance or shipment. A provision is recorded upon revenue recognition to cost of revenues for estimated warranty expense based on historical experience. Related costs are charged to the warranty accrual as incurred.The balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2017 $ 8,200 Acquisition 41 Accruals for warranties issued during the period 13,045 Accruals related to pre-existing warranties 921 Settlements made during the period (14,298 ) Balance at December 31, 2018 7,909 Acquisition 14 Accruals for warranties issued during the period 14,106 Accruals related to pre-existing warranties 4,026 Settlements made during the period (17,059 ) Balance at December 31, 2019 8,996 Accruals for warranties issued during the period 28,490 Accruals related to pre-existing warranties 821 Settlements made during the period (21,674 ) Balance at December 31, 2020 $ 16,633 When Teradyne receives revenue for extended warranties, beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2017 $ 24,438 Deferral of new extended warranty revenue 23,753 Recognition of extended warranty deferred revenue (20,769 ) Balance at December 31, 2018 27,422 Deferral of new extended warranty revenue 23,271 Recognition of extended warranty deferred revenue (20,016 ) Balance at December 31, 2019 30,677 Deferral of new extended warranty revenue 41,694 Recognition of extended warranty deferred revenue (20,442 ) Balance at December 31, 2020 $ 51,929 Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not bear interest. Teradyne maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Estimated allowances for doubtful accounts are reviewed periodically taking into account the customer’s recent payment history, the customer’s current financial statements and other information regarding the customer’s credit worthiness. Account balances are written off against the allowance when it is determined the receivable will not be recovered. Teradyne sells certain trade accounts receivables on a non-recourse basis to third-party financial institutions pursuant to factoring agreements. Teradyne accounts for these transactions as sales of receivables and presents cash proceeds as a cash provided by operating activities in the consolidated statements of cash flows. Total trade accounts receivable sold under the factoring agreements were $131.1 million and $143.6 million during 2020 and 2019, respectively. Factoring fees for the sales of receivables are recorded in interest expense and are not material. Inventories Inventories are stated at the lower of cost (first-in, first-out basis) or net realizable value. On a quarterly basis, Teradyne uses consistent methodologies to evaluate all inventories for net realizable value. Teradyne records a provision for both excess and obsolete inventory when such write-downs or write-offs are identified through the quarterly review process. The inventory valuation is based upon assumptions about future demand, product mix and possible alternative uses. Investments Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, “ Investments—Debt and Equity Securities • The length of time and the extent to which the market value has been less than cost; • The financial condition and near-term prospects of the issuer; and • The intent and ability to retain the investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. Teradyne uses the market and income approach techniques to value its financial instruments and there were no changes in valuation techniques during the twelve months ended December 31, 2020 and 2019. As defined in ASC 820-10, “ Fair Value Measurements and Disclosures, Level 1: Quoted prices in active markets for identical assets as of the reporting date; Level 2: Inputs other than Level 1, that are observable either directly or indirectly as of the reporting date. For example, a common approach for valuing fixed income securities is the use of matrix pricing. Matrix pricing is a mathematical technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, and 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. In accordance with ASC 820-10, Teradyne measures its debt and equity investments at fair value. Teradyne’s debt investments are classified as Level 2, and equity investments are classified as Level 1. Acquisition-related contingent consideration is classified as Level 3. Teradyne determines the fair value of acquisition-related contingent consideration using a Monte Carlo simulation model. Assumptions utilized in the model include forecasted revenues, revenue volatility, earnings before interest and taxes, and discount rate. Financial Assets and Financial Liabilities In January 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-01, “ Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities Prepayments Prepayments consist of the following and are included in prepayments and other current assets on the balance sheet: 2020 2019 (in thousands) Contract manufacturer and supplier prepayments $ 212,286 $ 143,392 Prepaid taxes 9,361 8,046 Prepaid maintenance and other services 13,116 8,503 Other prepayments 15,329 16,753 Total prepayments $ 250,092 $ 176,694 Retirement and Postretirement Plans Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans. 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 Goodwill, Intangible and Long-Lived Assets Teradyne accounts for goodwill and intangible assets in accordance with ASC 350-10, “ Intangibles-Goodwill and Other. of December 31, on a reporting unit basis, or more frequently when events and circumstances occur indicating that the recorded goodwill may be impaired. In accordance with ASC 350-10, Teradyne has the option to perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If Teradyne determines this is the case, Teradyne is required to perform a quantitative goodwill impairment test to identify potential goodwill impairment and measure the amount of goodwill impairment loss to be recognized. If Teradyne determines that it is more likely than not that the fair value of the reporting unit is greater than its carrying amounts, a quantitative goodwill impairment test is not required. In accordance with ASC 360-10, “ Impairment or Disposal of Long-Lived Assets, Business Combination Teradyne recognizes the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values at the date of acquisition. The fair value of identifiable intangible assets is based on detailed cash flows valuations that use information and assumptions provided by management. Teradyne estimates the fair value of contingent consideration at the time of the acquisition using all pertinent information known to us at the time to assess the probability of payment of contingent amounts or through the use of a Monte Carlo simulation model. Teradyne allocates any excess purchase price over the fair value of the net tangible and intangible assets acquired and liabilities assumed to goodwill. The assumptions used in the valuations for our acquisitions may differ materially from actual results depending on performance of the acquired businesses and other factors. While Teradyne believes the assumptions used were appropriate, different assumptions in the valuation of assets acquired and liabilities assumed could have a material impact on the timing and extent of impact on our statements of operations. Goodwill is assigned to reporting units as of the date of the related acquisition. Property, Plant and Equipment Property, plant and equipment are stated at cost and depreciated over the estimated useful lives of the assets. Leasehold improvements and major renewals are capitalized and included in property, plant and equipment accounts, while expenditures for maintenance and repairs and minor renewals are charged to expense. When assets are retired, the assets and related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations. Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 Building improvements 5 Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 Machinery, equipment and software 3 Test systems manufactured internally are used by Teradyne for customer evaluations and manufacturing and support of its customers. Teradyne depreciates the test systems manufactured internally over a six-year internally manufactured test equipment to customers. Upon the sale of an internally manufactured test system, the net book value of the system is transferred to inventory and expensed as cost of revenues. The net book value of internally manufactured test systems sold in the years ended December 31, 2020, 2019, and 2018 was $7.3 million, $5.0 million, and $3.8 million, respectively. Leases Teradyne adopted Accounting Standards Update (“ASU”) 2016-02, “ Leases (Topic 842) Leases (Topic 842): Targeted Improvements Under ASC 842, a contract is or contains a lease when Teradyne has the right to control the use of an identified asset. Teradyne determines if an arrangement is a lease at inception of the contract, which is the date on which the terms of the contract are agreed to and the agreement creates enforceable rights and obligations. The commencement date of the lease is the date that the lessor makes an underlying asset available for use by Teradyne. As of December 31, 2020, Teradyne does not have material leases that have not yet commenced. Teradyne determines if the lease is an operating or finance lease at the lease commencement date based upon the terms of the lease and the nature of the asset. The lease term used to calculate the lease liability includes options to extend or terminate the lease when it is reasonably certain that the option will be exercised. For leases commencing after January 1, 2019, the lease liability is measured at the present value of future lease payments, discounted using the discount rate for the lease at the commencement date. As Teradyne is typically unable to determine the implicit rate, Teradyne uses an incremental borrowing rate based on the lease term and economic environment at commencement date. Teradyne initially measures payments based on an index by using the applicable rate at lease commencement. Variable payments that do not depend on an index are not included in the lease liability and are recognized as they are incurred. The ROU asset is initially measured as the amount of lease liability, adjusted for any initial lease costs, prepaid lease payments, and reduced by any lease incentives. Teradyne’s contracts often include non-lease components such as common area maintenance. Teradyne elected the practical expedient to account for the lease and non-lease components as a single lease component. For leases with a term of one year or less Teradyne has elected not to record the lease asset or liability. The lease payments are recognized in the consolidated statement of earnings on a straight-line basis over the lease term. Teradyne includes lease costs within cost of revenues and operating expenses. See Note I: “Leases.” Engineering and Development Costs Teradyne’s products are highly technical in nature and require a large and continuing engineering and development effort. Software development costs incurred prior to the establishment of technological feasibility are charged to expense. Software development costs incurred subsequent to the establishment of technological feasibility are capitalized until the product is available for release to customers. To date, the period between achieving technological feasibility and general availability of the product has been short and software development costs eligible for capitalization have not been material. Engineering and development costs are expensed as incurred and consist primarily of salaries, contractor fees including non-recurring engineering charges related to product design, allocated facility costs, depreciation, and tooling costs. Stock Compensation Plans and Employee Stock Purchase Plan Stock-based compensation expense is based on the grant-date fair value estimated in accordance with the provisions of ASC 718-10, “ Compensation-Stock Compensation Excess tax benefits or tax deficiencies are recognized as a discrete tax benefit or discrete tax expense to the current income tax provision in Teradyne’s consolidated statements of operations, all excess tax benefits related to share-based payments are reported as cash flows from operating activities, and all cash payments made to taxing authorities on the employees’ behalf for withheld shares are presented as financing activities on the statement of cash flows. Teradyne elects to account for forfeitures by applying an estimated forfeiture rate and recognizes compensation costs only for those stock-based compensation awards expected to vest. Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The measurement of deferred tax assets is reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be realized. Teradyne performed the required assessment of positive and negative evidence regarding the realization of the net deferred tax assets in accordance with ASC 740, “Accounting for Income Taxes.” Advertising Costs Teradyne expenses all advertising costs as incurred. Advertising costs were $12.8 million, $16.6 million and $15.4 million in 2020, 2019 and 2018, respectively. Translation of Non-U.S. Currencies The functional currency for all non-U.S. subsidiaries is the U.S. dollar, except for Universal Robots, MiR and Lemsys for which the local currency is its functional currency. All foreign currency denominated monetary assets and liabilities are remeasured on a monthly basis into the functional currency using exchange rates in effect at the end of the period. All foreign currency denominated non-monetary assets and liabilities are remeasured into the functional currency using historical exchange rates. Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For Universal Robots, MiR and Lemsys, assets and liabilities are translated into U.S. dollars using exchange rates in effect at the end of the period. Revenues and expense amounts are translated using an average of exchange rates in effect during the period. Translation adjustments are recorded within accumulated other comprehensive income (loss) on the balance sheet. Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For the years ended December 31, 2020, 2019, and 2018, losses (gains) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $2.6 million, $(1.6) million, and $(2.5) million, respectively. These amounts do not reflect the corresponding (gains) losses from foreign exchange contracts. See Note H: “Financial Instruments” regarding foreign exchange contracts. Net Income (Loss) per Common Share Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Except where the result would be anti-dilutive, diluted net income (loss) per common share is calculated by dividing net income (loss) by the sum of the weighted average number of common shares plus common stock equivalents, if applicable. With respect to its convertible debt issued in 2016, Teradyne has determined that it has the ability and intent to settle the principal of the convertible debt in cash; accordingly, the principal amount is excluded from the determination of diluted earnings per share. As a result, Teradyne is accounting for the conversion spread using the treasury stock method. Comprehensive Income (Loss) Comprehensive income (loss) includes net income, unrealized pension and postretirement prior service costs and benefits, unrealized gains and losses on investments in debt marketable securities and foreign currency translation adjustment. Prior to 2018, comprehensive income (loss) included unrealized gains and losses on investments in equity marketable securities.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2020
Recently Issued Accounting Pronouncements	C. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS In August 2020, the FASB issued ASU 2020-06 — “Debt — —

Acquisitions and Investment in

Acquisitions and Investment in Other Company	12 Months Ended
	Dec. 31, 2020
Acquisitions and Investment in Other Company	D. ACQUISITIONS AND INVESTMENT IN OTHER COMPANY Acquisitions AutoGuide LLC On November 13, 2019, Teradyne acquired 100% of the membership interests of AutoGuide, LLC (“AutoGuide”), a maker of high-payload AMRs, based in Chelmsford, MA, an emerging and fast growing segment of the global forklift market. The total purchase price was approximately $81.6 million, which included cash paid of approximately $57.6 million and $24.0 million in fair value of contingent consideration payable upon achievement of certain performance targets, extending potentially through 2022. At December 31, 2020, the maximum contingent consideration that could be paid is $100.2 million. The contingent consideration is payable upon achievement of certain thresholds and targets for revenue and earnings before interest and taxes for periods from January 1, 2019 to December 31, 2020, January 1, 2019 to December 31, 2021, and January 1, 2019 to December 31, 2022. The valuation of the contingent consideration is dependent on the following assumptions: forecasted revenues, revenue volatility, earnings before interest and taxes, and discount rate. These assumptions were estimated based on a review of the historical and projected results. The AutoGuide acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s consolidated results of operations from the date of acquisition. AutoGuide’s AMRs are used for material transport of payloads up to 4,500 kg in manufacturing, warehouse and logistics applications. These products complement Mobile Industrial Robots A/S (“MiR”) lower payload products and expand the Industrial Automation segment, which is a key component of Teradyne’s growth strategy. The allocation of the total purchase price to AutoGuide’s net tangible assets and identifiable intangible assets was based on their fair values as of the acquisition date. The excess of the purchase price over the identifiable intangible assets and net tangible assets in the amount of $41.2 million was allocated to goodwill, which is deductible for tax purposes. AutoGuide’s results have been included in Teradyne’s Industrial Automation segment from the date of acquisition. The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 41,223 Intangible assets 37,660 Tangible assets acquired and liabilities assumed: Other current assets 3,661 Non-current assets 1,227 Accounts payable and current liabilities (1,223 ) Long-term other liabilities (949 ) Total purchase price $ 81,599 Teradyne estimated the fair value of intangible assets using the income approach. Forecasted revenues is the key assumption for estimating the fair value. Acquired intangible assets are amortized on a straight-line basis over their estimated useful lives. Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 24,590 6.0 Customer relationships 7,360 6.0 Trademarks and tradenames 5,450 7.0 Backlog 260 0.3 Total intangible assets $ 37,660 6.1 For the period from November 13, 2019 to December 31, 2019, AutoGuide contributed $1.4 million of revenues and had a $(0.9) million loss before income taxes. Lemsys SA On January 30, 2019, Teradyne acquired all of the issued and outstanding shares of Lemsys SA (“Lemsys”) for a total purchase price of approximately $9.1 million. Lemsys strengthens Teradyne’s position in the electrification trends of vehicles, solar and wind power, and industrial applications. The Lemsys acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s Semiconductor Test segment from the date of acquisition. Teradyne’s final allocation of the purchase price was goodwill of $1.4 million, which is not deductible for tax purposes, acquired intangible assets of $4.6 million with an average estimated useful life of 5.2 years, and $3.1 million of net tangible assets. The acquisition was not material to Teradyne’s consolidated financial statements. Mobile Industrial Robots On April 25, 2018, Teradyne acquired all of the issued and outstanding shares of MiR, a Danish limited liability company located in Odense, Denmark. MiR is a leading maker of collaborative autonomous mobile robots for industrial applications. The total purchase price of $197.8 million included $145.2 million of cash paid and $52.6 million of contingent consideration measured at fair value. The contingent consideration is payable in Euros upon the achievement of certain thresholds and targets for revenue and earnings before interest and taxes for periods from January 1, 2018 to December 31, 2018; January 1, 2018 to December 31, 2019; and January 1, 2018 to December 31, 2020. Contingent consideration for the period from January 1, 2018 to December 31, 2018 was $31.0 million and was paid in March 2019. Contingent consideration for the period from January 1, 2018 to December 31, 2019 was $9.1 million, based on the results during the period and modification of the earn-out structure, and was paid in March 2020. No contingent consideration will be paid out against the period from December 31, 2018 through December 31, 2020. The valuation of the contingent consideration is dependent on the following assumptions: forecasted revenues, revenue volatility, earnings before interest and taxes, and discount rate. These assumptions were estimated based on a review of the historical and projected results. The MiR acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s consolidated results of operations from the date of acquisition. MiR’s products will help expand the Industrial Automation segment, which is a key component of our growth strategy. The allocation of the total purchase price to MiR’s net tangible liabilities and identifiable intangible assets was based on their estimated fair values as of the acquisition date. The excess of the purchase price over the identifiable intangible assets and net tangible liabilities in the amount of $136.0 million was allocated to goodwill, which is not deductible for tax purposes. MiR’s results have been included in Teradyne’s Industrial Automation segment from the date of acquisition. The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 135,976 Intangible assets 80,670 Tangible assets acquired and liabilities assumed: Current assets 6,039 Non-current assets 1,336 Accounts payable and current liabilities (7,336 ) Long-term deferred tax liabilities (18,007 ) Other long-term liabilities (900 ) Total purchase price $ 197,778 Teradyne estimated the fair value of intangible assets using the income and cost approaches. Acquired intangible assets are amortized on a straight-line basis over their estimated useful lives. Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in Developed technology $ 58,900 7.0 Trademarks and tradenames 13,240 11.0 Customer relationships 8,500 2.5 Backlog 30 0.2 Total intangible assets $ 80,670 7.2 Energid Technologies Corporation On February 26, 2018, Teradyne acquired all of the issued and outstanding shares of Energid for a total 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 purchase price allocation was goodwill of $14.4 million which is deductible for tax purposes, acquired intangible assets of $12.3 million with an average estimated useful life of 7.7 years, and $1.0 million of net tangible assets. The acquisition was not material to Teradyne’s consolidated financial statements. Pro Forma Information The following unaudited pro forma information gives effect to the acquisition of AutoGuide as if the acquisition occurred on January 1, 2018 and the acquisition of MiR as if the acquisition occurred on January 1, 2017. The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented:​​​​​​​ December 31, 2019 December 31, 2018 (in thousands, except per share amount) Revenues $ 2,303,737 $ 2,111,373 Net income $ 464,602 $ 442,082 Net income per common share: Basic $ 2.73 $ 2.36 Diluted $ 2.59 $ 2.30 Pro forma results for the year ended December 31, 2019 were adjusted to exclude $1.2 million of AutoGuide acquisition related costs and $0.1 million of AutoGuide non-recurring expense related to fair value adjustment to acquisition-date inventory. Pro forma results for the year ended December 31, 2018 were adjusted to include $1.2 million of AutoGuide acquisition related costs and $0.1 million of AutoGuide non-recurring expense related to fair value adjustment to acquisition-date inventory. Pro forma results for the year ended December 31, 2018 were adjusted to exclude $2.9 million of MiR acquisition related costs and $0.4 million of MiR non-recurring expense related to fair value adjustment to acquisition-date inventory. Investment in Other Company On June 3, 2019, Teradyne invested $15.0 million in RealWear, Inc. (“RealWear”). RealWear, a private company, develops and sells advanced wearable technology including industrial, hands-free, head-mounted augmented reality devices that make the workplace safer and more productive. The investment was recorded at cost and is evaluated for impairment or an indication of changes in fair value resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer on a quarterly basis. On February 28, 2020, RealWear’s debt holder demanded repayment of its $25.0 million loan to RealWear. As a result, in the fourth quarter of 2019, Teradyne recorded an impairment charge of $15.0 million to reduce its investment in RealWear to zero

Revenue

Revenue	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue	E. REVENUE Disaggregation of Revenue The following table provides information about disaggregated revenue by timing of revenue recognition, primary geographical market, and major product lines. Semiconductor Test Industrial Automation Wireless Corporate and Other Total System on-a-chip Memory System Test Universa l Mobile AutoGuide (in thousands) For the Year Ended December 31, 2020 (1) Timing of Revenue Recognition Point in Time $ 1,659,414 $ 363,324 $ 348,454 $ 214,212 $ 44,622 $ 10,911 $ 163,834 $ (604 ) $ 2,804,166 Over Time 217,975 18,884 61,275 7,269 211 2,506 9,182 — 317,302 Total $ 1,877,389 $ 382,208 $ 409,729 $ 221,481 $ 44,833 $ 13,417 $ 173,016 $ (604 ) $ 3,121,469 Geographical Market Asia Pacific $ 1,744,593 $ 364,000 $ 258,521 $ 60,277 $ 6,471 $ — $ 143,969 $ — $ 2,577,831 Americas 77,671 12,999 128,482 64,164 16,769 13,417 22,544 (604 ) 335,441 Europe, Middle East and Africa 55,125 5,209 22,726 97,040 21,593 — 6,503 — 208,196 Total $ 1,877,389 $ 382,208 $ 409,729 $ 221,481 $ 44,833 $ 13,417 $ 173,016 $ (604 ) $ 3,121,469 For the Year Ended December 31, 2019 (1) Timing of Revenue Recognition Point in Time $ 1,070,375 $ 247,221 $ 237,686 $ 244,515 $ 44,329 $ 1,144 $ 148,322 $ (515 ) $ 1,993,077 Over Time 216,065 18,910 49,769 7,843 74 234 8,993 — 301,888 Total $ 1,286,440 $ 266,131 $ 287,455 $ 252,358 $ 44,403 $ 1,378 $ 157,315 $ (515 ) $ 2,294,965 Geographical Market Asia Pacific $ 1,152,881 $ 238,714 $ 132,826 $ 68,027 $ 9,513 $ — $ 126,549 $ — $ 1,728,510 Americas 73,257 23,826 129,840 71,926 14,438 1,378 24,234 (515 ) 338,384 Europe, Middle East and Africa 60,302 3,591 24,789 112,405 20,452 — 6,532 — 228,071 Total $ 1,286,440 $ 266,131 $ 287,455 $ 252,358 $ 44,403 $ 1,378 $ 157,315 $ (515 ) $ 2,294,965 For the Year Ended December 31, 2018 (1) Timing of Revenue Recognition Point in Time $ 1,010,493 $ 259,366 $ 167,418 $ 232,448 $ 24,115 $ — $ 122,536 $ (1,205 ) $ 1,815,171 Over Time 208,456 14,102 48,714 4,889 — — 9,470 — 285,631 Total $ 1,218,949 $ 273,468 $ 216,132 $ 237,337 $ 24,115 $ — $ 132,006 $ (1,205 ) $ 2,100,802 Geographical Market Asia Pacific $ 1,067,879 $ 245,264 $ 90,989 $ 58,492 $ 5,950 $ — $ 107,872 $ — $ 1,576,446 Americas 78,498 17,353 96,763 70,478 7,326 — 19,166 (1,205 ) 288,379 Europe, Middle East and Africa 72,572 10,851 28,380 108,367 10,839 — 4,968 — 235,977 Total $ 1,218,949 $ 273,468 $ 216,132 $ 237,337 $ 24,115 $ — $ 132,006 $ (1,205 ) $ 2,100,802 (1) Includes $10.0 million, $8.4 million and $12.0 million in 2020, 2019 and 2018, respectively, for leases of Teradyne’s systems recognized outside of ASC 606: “Revenue from Contracts with Customers.” Contract Balances For the years ended December 31, 2020, 2019 and 2018, Teradyne recognized $91.0 million, $65.6 million and $69.9 million, respectively, that was included within the deferred revenue and customer advances balances at the beginning of the period. This revenue primarily relates to undelivered hardware, extended warranties, training, application support, and post contract support. Each of these represents a distinct performance obligation. As of December 31, 2020, T expects to recognize 92% of the remaining performance obligation in the next 12 months, 8% in 1-3 years, and the remainder thereafter.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Inventories	F. INVENTORIES Inventories, net consisted of the following at December 31, 2020 and 2019: 2020 2019 (in thousands) Raw material $ 114,133 $ 118,595 Work-in-process 25,408 32,695 Finished goods 82,648 45,401 $ 222,189 $ 196,691 Inventory reserves for the years ended December 31, 2020 and 2019 were $110.6 million and $103.6 million, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment	G. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment, net consisted of the following at December 31, 2020 and 2019: 2020 2019 (in thousands) Land $ 17,207 $ 16,561 Buildings 108,221 107,282 Machinery, equipment and software 956,035 834,970 Furniture and fixtures 28,487 29,157 Leasehold improvements 61,276 59,378 Construction in progress 13,098 2,537 1,184,324 1,049,885 Less: accumulated depreciation 789,524 729,669 $ 394,800 $ 320,216 Depreciation of property, plant and equipment for the years ended December 31, 2020, 2019, and 2018 was $80.1 million, $70.8 million, and $67.4 million, respectively. As of December 31, 2020 and 2019, the gross book value included in machinery and equipment for internally manufactured test systems being leased by customers was $23.4 million and $5.4 million, respectively. As of December 31, 2020 and 2019, the accumulated depreciation on these test systems was $7.5 million and $5.1 million, respectively.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2020
Financial Instruments	H. FINANCIAL INSTRUMENTS Cash Equivalents Teradyne considers all highly liquid investments with maturities of three months or less at the date of acquisition to be cash equivalents. Marketable Securities Teradyne recognizes the changes in fair value of equity securities directly in earnings. Teradyne’s available-for-sale debt securities are classified as Level 2, and equity and debt mutual funds are classified as Level 1. Contingent consideration is classified as Level 3. The vast majority of Level 2 securities are fixed income securities priced by third party pricing vendors. These pricing vendors utilize the most recent observable market information in pricing these securities or, if specific prices are not available, use other observable inputs like market transactions involving identical or comparable securities. During the years ended December 31, 2020 and 2019, there were no transfers in or out of Level 1, Level 2, or Level 3 financial instruments. Realized gains recorded in 2020, 2019, and 2018 were $4.6 million, $1.3 million, and $4.0 million, respectively. Realized losses recorded in 2020, 2019, and 2018 were $0.3 million, $0.2 million, and $1.6 million, respectively. Realized gains and losses are included in other (income) expense, net. Unrealized gains on equity securities recorded during the years ended December 31, 2020 and 2019 were $9.6 million and $5.3 million, respectively. Unrealized losses on equity securities recorded during the years ended December 31, 2020 and 2019 were $6.0 million and $0.4 million, respectively. Unrealized gains and losses on equity securities are included in other (income) expense, net. Unrealized gains and losses on available-for-sale debt securities are included in accumulated other comprehensive income (loss) on the balance sheet. The cost of securities sold is based on the first-in first out method. The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2020 and 2019: December 31, 2020 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 $ 443,166 $ — $ — $ 443,166 Cash equivalents 347,768 123,187 — 470,955 Available for sale securities: U.S. Treasury securities — 258,304 — 258,304 Commercial paper — 254,413 — 254,413 Corporate debt securities — 83,615 — 83,615 Debt mutual funds 8,565 — — 8,565 U.S. government agency securities — 4,339 — 4,339 Certificates of deposit and time deposits — 979 — 979 Non-U.S. government securities — 625 — 625 Equity securities: Mutual funds 29,420 — — 29,420 Total $ 828,919 $ 725,462 $ — $ 1,554,381 Derivative assets — 95 — 95 Total $ 828,919 $ 725,557 $ — $ 1,554,476 Liabilities Contingent consideration $ — $ — $ 7,227 $ 7,227 Derivative liabilities — 504 — 504 Total $ — $ 504 $ 7,227 $ 7,731 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 790,934 $ 123,187 $ — $ 914,121 Marketable securities — 522,280 — 522,280 Long-term marketable securities 37,985 79,995 — 117,980 Prepayments and other current assets — 95 — 95 Total $ 828,919 $ 725,557 $ — $ 1,554,476 Liabilities Other current liabilities $ — $ 504 $ — $ 504 Long-term contingent consideration — — 7,227 7,227 Total $ — $ 504 $ 7,227 $ 7,731 December 31, 2019 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 $ 311,975 $ — $ — $ 311,975 Cash equivalents 410,285 51,664 — 461,949 Available for sale securities: Corporate debt securities — 97,307 — 97,307 Commercial paper — 54,149 — 54,149 U.S. Treasury securities — 42,382 — 42,382 U.S. government agency securities — 9,952 — 9,952 Debt mutual funds 6,888 — — 6,888 Certificates of deposit and time deposits — 4,751 — 4,751 Non-U.S. government securities — 592 — 592 Equity securities: Mutual funds 25,772 — — 25,772 Total $ 754,920 $ 260,797 $ — $ 1,015,717 Derivative assets — 528 — 528 Total $ 754,920 $ 261,325 $ — $ 1,016,245 Liabilities Contingent consideration $ — $ — $ 39,705 $ 39,705 Derivative liabilities — 203 — 203 Total $ — $ 203 $ 39,705 $ 39,908 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 722,260 $ 51,664 $ — $ 773,924 Marketable securities — 137,303 — 137,303 Long-term marketable securities 32,660 71,830 — 104,490 Prepayments and other current assets — 528 — 528 Total $ 754,920 $ 261,325 $ — $ 1,016,245 Liabilities Other current liabilities $ — $ 203 $ — $ 203 Contingent consideration — — 9,106 9,106 Long-term contingent consideration — — 30,599 30,599 Total $ — $ 203 $ 39,705 $ 39,908 Changes in the fair value of Level 3 contingent consideration for the years ended December 31, 2020 and 2019 were as follows: Contingent Consideration (in thousands) Balance at December 31, 2018 $ 70,543 Acquisition of AutoGuide 23,976 Foreign currency impact (967 ) Payments (1) (34,590 ) Fair value adjustment (2) (19,257 ) Balance at December 31, 2019 39,705 Foreign currency impact (355 ) Payments (3) (8,852 ) Fair value adjustment (4) (23,271 ) Balance at December 31, 2020 $ 7,227 (1) During the year ended December 31, 2019, Teradyne paid $30.8 million and $3.8 million of contingent consideration for the earn-outs in connection with the acquisitions of MiR and Universal Robots A/S (“Universal Robots”), respectively. (2) During the year ended December 31, 2019, the fair value of contingent consideration for the earn-out in connection with the acquisition of MiR was decreased by $22.2 million primarily due to a decrease in forecasted revenues partially offset by the impact from modification of the earn-out structure. During the year ended December 31, 2019, the fair value of contingent consideration for the earn-out in connection with the acquisition of AutoGuide was increased by $3.0 million primarily due to an increase in forecasted revenues (3) During the year ended December 31, 2020, Teradyne paid $8.9 million of contingent consideration for the earn-out in connection with the acquisition of MiR. (4) During the year ended December 31, 2020, the fair value of contingent consideration for the earn-out in connection with the acquisition of AutoGuide was decreased by $19.7 million primarily due to a decrease in forecasted revenues and earnings before interest and taxes The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instrument: Liability December 31, 2020 Fair Value Valuation Technique Unobservable Inputs Weighted Average (in thousands) Contingent consideration (AutoGuide) $ 7,227 Monte Carlo simulation Revenue Volatility 16.5% Discount Rate 1.0% As of December 31, 2020, the significant unobservable inputs used in the Monte Carlo simulation to fair value the AutoGuide contingent consideration include forecasted revenues, revenue volatility, earnings before interest and taxes and discount rate. Increases or decreases in the inputs would result in a higher or lower fair value measurement. As of December 31, 2020, the maximum amount of contingent consideration that could be paid in connection with the acquisition of AutoGuide is $100.2 million. No payment was made related to the period ending December 31, 2020. The remaining earn-out periods end on December 31, 2021 and December 31, 2022. The carrying amounts and fair values of Teradyne’s financial instruments at December 31, 2020 and 2019 were as follows: December 31, 2020 December 31, 2019 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 914,121 $ 914,121 $ 773,924 $ 773,924 Marketable securities 640,260 640,260 241,793 241,793 Derivative assets 95 95 528 528 Liabilities Contingent consideration 7,227 7,227 39,705 39,705 Derivative liabilities 504 504 203 203 Convertible debt (1) 410,111 1,739,553 394,687 1,010,275 (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 amount due to the short term nature of these instruments. The following tables summarize the composition of available-for-sale marketable securities at December 31, 2020 and 2019: December 31, 2020 Available-for-Sale Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) U.S. Treasury securities $ 257,132 $ 1,330 $ (158 ) $ 258,304 $ 17,243 Commercial paper 254,404 10 (1 ) 254,413 12,173 Corporate debt securities 76,129 7,539 (53 ) 83,615 39,896 Debt mutual funds 8,413 152 — 8,565 — U.S. government agency securities 4,294 46 (1 ) 4,339 1,106 Certificates of deposit and time deposits 979 — — 979 — Non-U.S. government securities 625 — — 625 — $ 601,976 $ 9,077 $ (213 ) $ 610,840 $ 70,418 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 522,228 $ 92 $ (40 ) $ 522,280 $ 61,806 Long-term marketable securities 79,748 8,985 (173 ) 88,560 8,612 $ 601,976 $ 9,077 $ (213 ) $ 610,840 $ 70,418 December 31, 2019 Available-for-Sale Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Corporate debt securities $ 93,267 $ 4,081 $ (41 ) $ 97,307 $ 2,009 Commercial paper 54,124 26 (1 ) 54,149 1,391 U.S. Treasury securities 42,167 431 (216 ) 42,382 17,556 U.S. government agency securities 9,942 14 (4 ) 9,952 3,043 Debt mutual funds 6,753 135 — 6,888 — Certificates of deposit and time deposits 4,751 — — 4,751 — Non-U.S. government securities 592 — — 592 — $ 211,596 $ 4,687 $ (262 ) $ 216,021 $ 23,999 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 137,144 $ 160 $ (1 ) $ 137,303 $ 2,922 Long-term marketable securities 74,452 4,527 (261 ) 78,718 21,077 $ 211,596 $ 4,687 $ (262 ) $ 216,021 $ 23,999 As of December 31, 2020, the fair market value of investments with unrealized losses less than one year totaled $70.4 million. As of December 31, 2019, the fair market value of investments with unrealized losses less than one year totaled $23.6 million. Teradyne reviews its investments to identify and evaluate investments that have an indication of possible impairment. Based on this review, Teradyne determined that the unrealized losses related to these investments at December 31, 2020 and 2019, were not other than temporary. The contractual maturities of investments in available-for-sale marketable securities held at December 31, 2020 were as follows: Cost Fair Value (in Due within one year $ 522,228 $ 522,280 Due after 1 year through 5 years 24,829 25,245 Due after 5 years through 10 years 13,030 14,183 Due after 10 years 33,476 40,567 Total $ 593,563 $ 602,275 Contractual maturities of investments in available-for-sale marketable securities held at December 31, 2020 exclude debt mutual funds with the fair market value of $8.6 million as they do not have a contractual maturity date. Derivatives Teradyne conducts business in a number of foreign countries, with certain transactions denominated in local currencies. The purpose of Teradyne’s foreign currency management is to minimize the effect of exchange rate fluctuations on certain foreign currency denominated monetary assets and liabilities. Teradyne does not use derivative financial instruments for trading or speculative purposes. To minimize the effect of exchange rate fluctuations associated with the remeasurement of monetary assets and liabilities denominated in foreign currencies, Teradyne enters into foreign currency forward contracts. The change in fair value of these derivatives is recorded directly in earnings, and is used to offset the change in value of the monetary assets and liabilities denominated in foreign currencies. At December 31, 2020 and 2019, Teradyne had the following contracts to buy and sell non-U.S. currencies for U.S. dollars and other non-U.S. currencies with the following notional amounts: December 31, 2020 December 31, 2019 Buy Position Sell Position Net Total Buy Position Sell Position Net Total (in millions) Japanese Yen $ (14.1 ) $ — $ (14.1 ) $ (29.3 ) $ — $ (29.3 ) Taiwan Dollar (27.9 ) — (27.9 ) (18.4 ) — (18.4 ) Korean Won (5.3 ) — (5.3 ) (10.7 ) — (10.7 ) British Pound Sterling (1.0 ) — (1.0 ) (3.8 ) — (3.8 ) Singapore Dollar — 52.3 52.3 — 25.3 25.3 Euro — 43.9 43.9 — 47.8 47.8 Philippine Peso — 5.0 5.0 — 5.2 5.2 Chinese Yuan — 3.4 3.4 — 4.4 4.4 Total $ (48.3 ) $ 104.6 $ 56.3 $ (62.2 ) $ 82.7 $ 20.5 The fair value of the outstanding contracts was a loss of $0.4 million and a gain of $0.3 million, respectively, at December 31, 2020 and 2019. Gains and losses on foreign currency forward contracts and foreign currency remeasurement gains and losses on monetary assets and liabilities are included in other (income) expense, net. The following table summarizes the fair value of derivative instruments as of December 31, 2020 and 2019: Balance Sheet Location December 31, 2020 December 31, 2019 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 95 $ 528 Foreign exchange contracts Other current liabilities (504 ) (203 ) Total derivatives $ (409 ) $ 325 The following table summarizes the effect of derivative instruments in the statements of operations recognized for the years ended December 31, 2020, 2019, and 2018. Location of (Gains) Losses Recognized in Statement of Operations December 31, 2020 December 31, 2019 December 31, 2018 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ 3,515 $ 5,960 $ 7,386 (1) The table does not reflect the corresponding gains and losses from the remeasurement of the monetary assets and liabilities denominated in foreign currencies. (2) For the years ended December 31, 2020, net losses from remeasurement of monetary assets and liabilities denominated in foreign currencies were $2.6 million. (3) For the year ended December 31, 2019 and 2018, net gains from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $1.6 million and $2.5 million, respectively. See Note J: “Debt” regarding derivatives related to the convertible senior notes. Concentration of Credit Risk Financial instruments which potentially subject Teradyne to concentrations of credit risk consist principally of cash equivalents, marketable securities, forward currency contracts and accounts receivable. Teradyne’s cash equivalents consist primarily of money market funds invested in U.S. Treasuries and government agencies. Teradyne’s fixed income available-for-sale marketable securities have a minimum rating of AA by one or more of the major credit rating agencies. Teradyne places foreign currency forward contracts with high credit-quality financial institutions in order to minimize credit risk exposure. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of geographically dispersed customers. Teradyne performs ongoing credit evaluations of its customers’ financial condition and from time to time may require customers to provide a letter of credit from a bank to secure accounts receivable. As of December 31, 2020, a customer of our Semiconductor Test segment, JA Mitsui Leasing, LTD, accounted for 25% of our accounts receivable balance. The balance was paid in full as of February 22, 2021. There were no customers who accounted for 10% or more of our accounts receivable balance as of December 31, 2019.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Lease	I. LEASES Teradyne has facility and auto leases, which are accounted for as operating leases. Teradyne’s facility leases are primarily used for administrative functions, research and development, manufacturing, and storage and distribution. Remaining lease terms range from less than one year to twelve years. Total lease expense for the year ended December 31, 2020 was $38.5 million and included $12.1 million of variable lease costs and $3.4 million of costs related to short-term leases, which are not recorded on the consolidated balance sheets. Total lease expense for the year ended December 31, 2019 was $35.6 million and included $11.1 million of variable lease costs and $2.6 million of costs related to short-term leases, which are not recorded on the consolidated balance sheets. At December 31, 2020, the weighted average remaining lease term and weighted average discount rate for operating leases was 4.2 years and 4.8%, respectively. At December 31, 2019, the weighted average remaining lease term and weighted average discount rate for operating leases was 4.5 years and 5.0%, respectively. Supplemental cash flows information related to leases was as follows: For the Year Ended Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows: $ 24,136 Right-of-use assets obtained in exchange for new lease obligations 14,801 Maturities of lease liabilities as of December 31, 2020 were as follows: Operating Lease (in thousands) 2021 $ 22,451 2022 16,798 2023 9,727 2024 7,215 2025 5,715 Thereafter 6,149 Total lease payments 68,055 Less imputed interest (5,409 ) Total lease liabilities $ 62,646

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt	J. DEBT Convertible Senior Notes On December 12, 2016, Teradyne completed a private offering of $460.0 million aggregate principal amount of 1.25% convertible senior unsecured notes (the “Notes”) due December 15, 2023 and received net proceeds, after issuance costs, of approximately $450.8 million, $33.0 million of which was used to pay the net cost of the convertible note hedge transactions and $50.1 million of which was used to repurchase 2.0 million shares of Teradyne’s common stock under its existing stock repurchase program from purchasers of the Notes in privately negotiated transactions effected through one of the initial purchasers or its affiliates conducted concurrently with the pricing of the Note offering. The Notes will mature on December 15, 2023, unless earlier repurchased or converted. The Notes bear interest at a rate of 1.25% per year payable semiannually in arrears on June 15 and December 15 of each year. 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, only 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 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 $31.56. The Note Hedge Transactions cover, subject to customary anti-dilution adjustments, approximately 14.6 million shares of Teradyne’s common stock. 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 (or, at its election subject to certain conditions, cash-settled) warrants to the Option Counterparties. The Warrant Transactions cover, subject to customary anti-dilution adjustments, approximately 14.6 million shares of common stock. As of December 31, 2020, the strike price of the warrants was approximately $39.60 per share. The strike price is subject to adjustment under certain circumstances. The Warrant Transactions could have a dilutive effect to Teradyne’s common stock to the extent that the market price per share of Teradyne’s common stock, as measured under the terms of the Warrant Transactions, exceeds the applicable strike price of the warrants. 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 Note Hedge Transactions, after being partially offset by the proceeds from the sale of the warrants, was approximately $33.0 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 considered the guidance of ASC 815-40, “Derivatives and Hedging—Contracts in Entity’s Own Equity,” Teradyne assessed whether the convertible note hedge should be classified as equity under ASC 815-40. In the Note Hedge Transactions contract the settlement terms permit net cash settlement or net share settlement, at the option of Teradyne. Therefore, the criteria as set forth in ASC 815-40 were evaluated by Teradyne. In reviewing the criteria, Teradyne noted the following: (1) the convertible note hedge does not require Teradyne to issue shares; (2) there is no requirement to net cash settle the convertible note hedge for failure to make timely filings with the SEC; (3) in the case of termination, the convertible note hedge is settled in the same consideration as the holders of the underlying stock; (4) the counterparty does not have rights that rank higher than those of a shareholder of the stock underlying the convertible note hedge; and (5) there is no requirement to post collateral. Based on its analysis of those criteria, Teradyne concluded that the convertible note hedge should be recorded in equity and no further adjustment should be made in future periods to adjust the value of the convertible note hedge. Teradyne analyzed the Warrant Transactions under ASC 815-40, “Derivatives and Hedging—Contracts in Entity’s Own Equity,” The provisions of ASC 470-20, “ Debt with Conversion and Other Options, on seven-year The below tables represent the key components of Teradyne’s convertible senior notes: December 31, December 31, (in thousands) Debt principal $ 459,971 $ 460,000 Unamortized discount 49,860 65,313 Net carrying amount of convertible debt $ 410,111 $ 394,687 Reported as follows: December 31, December 31, (in thousands) Current debt $ 33,343 $ — Long-term debt 376,768 394,687 Net carrying amount of convertible debt $ 410,111 $ 394,687 For the year ended December 31, December 31, (in thousands) Contractual interest expense on the coupon $ 5,750 $ 5,750 Amortization of the discount component and debt issue fees recognized as interest expense 15,454 14,706 Total interest expense on the convertible debt $ 21,204 $ 20,456 As of December 31, 2020, the unamortized discount was $49.9 million, which will be amortized over three years using the effective interest rate method. The carrying amount of the equity component was $100.8 million. As of December 31, 2020, the conversion price was approximately $31.56 per share and if converted the value of the notes was $1,747.5 million. As of December 31, 2020, certain holders have elected to convert approximately $37 million of debt principal. Conversions will occur in the first quarter of 2021. The related liability component is included in current debt and the portion of the equity component is included in convertible common shares. Revolving Credit Facility On June 27, 2019, Teradyne terminated its credit agreement, which Teradyne entered into with Barclays Bank PLC on April 27, 2015. The terminated credit agreement, which was undrawn at termination, provided for a five-year On three-year The interest rate applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.50% to 1.25% per annum or LIBOR, a minimum of 0.75%, plus a margin ranging from 1.50% to 2.25% per annum, based on the consolidated leverage ratio of Teradyne. In addition, Teradyne will pay a commitment fee on the unused portion of the commitments under the Credit Facility ranging from 0.25% to 0.40% 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 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. 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. As of December 31, 2020, Teradyne was in compliance with all covenants under the Credit Agreement.

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income	12 Months Ended
	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss)	K. ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME Changes in accumulated other comprehensive (loss) income, which is presented net of tax, consist of the following: Foreign Currency Translation Adjustment Unrealized (Losses) Gains on Marketable Securities Retirement Plans Service Credit Total (in thousands) Balance at December 31, 2018, net of tax of $0, $(521), $(1,081) $ (12,523 ) $ (1,845 ) $ 1,328 $ (13,040 ) Other comprehensive (loss) income before (10,991 ) 6,015 — (4,976 ) Amounts reclassified from accumulated other — (690 ) (148 ) (838 ) Net current period other comprehensive (loss) income, (10,991 ) 5,325 (148 ) (5,814 ) Balance at December 31, 2019, net of tax of $0, $946, $(1,124) $ (23,514 ) $ 3,480 $ 1,180 $ (18,854 ) Other comprehensive income before 48,903 5,839 — 54,742 Amounts reclassified from accumulated other — (2,365 ) (7 ) (2,372 ) Net current period other comprehensive income (loss), 48,903 3,474 (7 ) 52,370 Balance at December 31, 2020, net of tax of $0, $1,910, $(1,126) $ 25,389 $ 6,954 $ 1,173 $ 33,516 Reclassifications out of accumulated other comprehensive income to the statements of operations for the years ended December 31, 2020, 2019, and 2018, were as follows: Details about Accumulated Other Comprehensive Income Components For the year ended Affected Line Item in the Statements of Operations December 31, 2020 December 31, 2019 December 31, 2018 (in thousands) Available-for-sale marketable securities Unrealized gains (losses), net of tax of $665, $192, $21 $ 2,365 $ 690 $ (1,337 ) Interest income Defined benefit pension and postretirement plans: Amortization of prior service benefit, net of tax of $2, $43, $71 7 148 245 (a) Total reclassifications, net of tax of $667, $235, $92 $ 2,372 $ 838 $ (1,092 ) 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 Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets	L. GOODWILL AND INTANGIBLE ASSETS Goodwill Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, “ Intangibles—Goodwill and Other, Teradyne has the option to perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If Teradyne determines this is the case, Teradyne is required to perform a quantitative goodwill impairment test to identify potential goodwill impairment and measure the amount of goodwill impairment loss to be recognized. If Teradyne determines that it is more likely than not that the fair value of the reporting unit is greater than its carrying amounts, the quantitative goodwill impairment test is not required. In performing the quantitative goodwill impairment test, Teradyne determines the fair value of a reporting unit using the results derived from an income approach and a market approach, weighting the fair value determined under each approach to determine an estimated fair value for a reporting unit. The income approach is estimated through the discounted cash flows (“DCF”) analysis. Determining fair value requires the exercise of significant judgment, including judgments about appropriate discount rates, perpetual growth rates, and the amount and timing of expected future cash flows. Discount rates are based on a weighted average cost of capital (“WACC”), which represents the average rate a business must pay its providers of debt and equity, plus a risk premium. The WACC used to test goodwill is derived from a group of comparable companies. The cash flows employed in the DCF analysis are derived from internal forecasts and external market forecasts. The market approach estimates the fair value of the reporting unit by utilizing the market comparable method which is based on revenue and earnings multiples from comparable companies. If the estimated fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired. If the carrying amount of a reporting unit exceeds its estimated fair value, then the goodwill is written down by the amount that carrying value exceeds the fair value of the reporting unit, but not below zero. On September 15, 2020, Teradyne announced the appointment of Gregory Smith as President of Teradyne’s Industrial Automation reportable segment effective October 1, 2020. With the appointment of Gregory Smith, the Industrial Automation reportable segment, which includes UR, MiR and AutoGuide, is considered one operating segment and one reporting unit. Teradyne performed a goodwill impairment test at the time of the change in operating segments, which indicated the fair value of Teradyne’s reporting units exceeded their carrying values. In the fourth quarter of 2020, Teradyne performed the annual goodwill impairment test, completing a qualitative assessment for the Wireless Test, System Test, and Industrial Automation reporting units. There was no impairment as a result of the annual test performed in the fourth quarter of 2020. Key assumptions in the goodwill valuation model are forecasted revenues, discount rate, earnings before interest and taxes, and revenue multiples from comparable companies. A change in any of these key assumptions could result in the reporting unit being impaired in a future period. Based on Teradyne’s December 31, 2019 goodwill impairment test, the MiR reporting unit’s estimated fair value exceeded its carrying value by 14%. The MiR goodwill amount is $123.6 million as of December 31, 2019. Key assumptions in the goodwill valuation model are forecasted revenues, discount rate, earnings before interest and taxes, and revenue multiples from comparable companies. A change in any of these key assumptions could result in the reporting unit being impaired in a future period. In the fourth quarter of 2018, Teradyne performed the annual goodwill impairment test. Teradyne completed step one of the two-step impairment test for the Universal Robots reporting unit. Teradyne completed step zero for the Wireless Test and Defense/Aerospace, MiR, and Energid reporting units. There was no impairment as a result of the annual test performed in the fourth quarter of 2018. The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2020 and 2019 are as follows: Industrial Automation Wireless Test Semiconductor Test System Test Total (in thousands) Balance at December 31, 2018: Goodwill $ 363,358 $ 361,819 $ 260,540 $ 158,699 $ 1,144,416 Accumulated impairment losses — (353,843 ) (260,540 ) (148,183 ) (762,566 ) 363,358 7,976 — 10,516 381,850 Lemsys acquisition — — 1,428 — 1,428 AutoGuide acquisition 41,372 — — — 41,372 Foreign currency translation adjustment (8,247 ) — 28 — (8,219 ) Balance at December 31, 2019: Goodwill 396,483 361,819 261,996 158,699 1,178,997 Accumulated impairment losses — (353,843 ) (260,540 ) (148,183 ) (762,566 ) 396,483 7,976 1,456 10,516 416,431 AutoGuide acquisition (149 ) — — — (149 ) Foreign currency translation adjustment 37,418 — 159 — 37,577 Balance at December 31, 2020: Goodwill 433,752 361,819 262,155 158,699 1,216,425 Accumulated impairment losses — (353,843 ) (260,540 ) (148,183 ) (762,566 ) $ 433,752 $ 7,976 $ 1,615 $ 10,516 $ 453,859 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. There were no events or circumstances indicating that the carrying value of intangible and long-lived assets may not be recoverable in 2020, 2019 and 2018. Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets: December 31, 2020 Gross Carrying Amount Accumulated Amortization (1) Foreign Net Carrying Amount (in thousands) Developed technology $ 272,547 $ (210,479 ) $ (1,610 ) $ 60,458 Customer relationships 66,239 (54,524 ) 305 12,020 Tradenames and trademarks 70,120 (42,344 ) 685 28,461 Total intangible assets $ 408,906 $ (307,347 ) $ (620 ) $ 100,939 December 31, 2019 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 361,787 $ (279,000 ) $ (5,709 ) $ 77,078 Customer relationships 75,669 (59,077 ) (455 ) 16,137 Tradenames and trademarks 70,120 (36,671 ) (1,184 ) 32,265 Backlog 260 (260 ) — — Total intangible assets $ 507,836 $ (375,008 ) $ (7,348 ) $ 125,480 (1) In 2020, $98.9 million of amortizable intangible assets became fully amortized and have been eliminated from the gross carrying amount and accumulated amortization. Aggregate intangible assets amortization expense for the years ended December 31, 2020, 2019, and 2018, was $30.8 million, $40.1 million, and $39.2 million, respectively. Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2021 $ 21,893 2022 21,000 2023 20,504 2024 20,192 2025 11,922 Thereafter 5,428

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies	M. COMMITMENTS AND CONTINGENCIES Purchase Commitments As of December 31, 2020, Teradyne had entered into non-cancelable purchase commitments for certain components and materials. The purchase commitments covered by the agreements aggregate to approximately $603.5 million, of which $592.1 million is for less than one year. Legal Claims Teradyne is subject to legal proceedings, claims and investigations that arise in the ordinary course of business such as, but not limited to, patent, employment, commercial and environmental matters. Teradyne believes that it has meritorious defenses against all pending claims and intends to vigorously contest them. While it is not possible to predict or determine the outcomes of any pending claims or to provide possible ranges of losses that may arise, Teradyne believes the potential losses associated with all of these actions are unlikely to have a material adverse effect on its business, financial position or results of operations. Guarantees and Indemnification Obligations Teradyne provides indemnification, to the extent permitted by law, to its officers, directors, employees and agents for liabilities arising from certain events or occurrences, while the officer, director, employee, or agent, is or was serving, at Teradyne’s request in such capacity. Teradyne may enter into indemnification agreements with certain of its officers and directors. With respect to acquisitions, Teradyne provides indemnifications to or assumes indemnification obligations for the current and former directors, officers and employees of the acquired companies in accordance with the acquired companies’ by-laws and charter. As a matter of practice, Teradyne has maintained directors’ and officers’ liability insurance coverage including coverage for directors and officers of acquired companies. Teradyne enters into agreements in the ordinary course of business with customers, resellers, distributors, integrators and suppliers. Most of these agreements require Teradyne to defend and/or indemnify the other party against intellectual property infringement claims brought by a third party with respect to Teradyne’s products. From time to time, Teradyne also indemnifies customers and business partners for damages, losses and liabilities they may suffer or incur relating to personal injury, personal property damage, product liability, breach of confidentiality obligations and environmental claims relating to the use of Teradyne’s products and services or resulting from the acts or omissions of Teradyne, its employees, authorized agents or subcontractors. On occasion, Teradyne has also provided guarantees to customers regarding the delivery and performance of its products in addition to the warranty described below. As a matter of ordinary course of business, Teradyne warrants that its products will substantially perform in accordance with its standard published specifications in effect at the time of delivery. Most warranties have a one In addition, in the ordinary course of business, Teradyne provides minimum purchase guarantees to certain vendors to ensure continuity of supply against the market demand. Although some of these guarantees provide penalties for cancellations and/or modifications to the purchase commitments as the market demand decreases, most of the guarantees do not. Therefore, as the market demand decreases, Teradyne re-evaluates these guarantees and determines what charges, if any, should be recorded. With respect to its agreements covering product, business or entity divestitures and acquisitions, Teradyne provides certain representations, warranties and covenants to purchasers and agrees to indemnify and hold such purchasers harmless against breaches of such representations, warranties and covenants. Many of the indemnification claims have a definite expiration date while some remain in force indefinitely. With respect to its acquisitions, Teradyne may, from time to time, assume the liability for certain events or occurrences that took place prior to the date of acquisition. As a matter of ordinary course of business, Teradyne occasionally guarantees certain indebtedness obligations of its subsidiary companies, limited to the borrowings from financial institutions, purchase commitments to certain vendors, and lease commitments to landlords. Based on historical experience and information known as of December 31, 2020, and 2019, except for product warranty, Teradyne has not recorded any liabilities for these guarantees and obligations because the amount would be immaterial.

Net Income Per Common Share

Net Income Per Common Share	12 Months Ended
	Dec. 31, 2020
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: 2020 2019 2018 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 784,147 $ 467,468 $ 451,779 Weighted average common shares-basic 166,120 170,425 187,672 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) 8,528 4,909 2,749 Convertible note hedge warrant shares (2) 6,989 2,698 485 Restricted stock units 1,264 1,236 1,385 Stock options 131 178 278 Employee stock purchase rights 10 13 36 Dilutive potential common shares 16,922 9,034 4,933 Weighted average common shares-diluted 183,042 179,459 192,605 Net income per common share-basic $ 4.72 $ 2.74 $ 2.41 Net income per common share-diluted $ 4.28 $ 2.60 $ 2.35 (1) Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.56, multiplied by 14.6 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 $39.60, multiplied by 14.6 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 2020 excludes the effect of the potential exercise of stock options to purchase approximately 0.1 million shares and restricted stock units to purchase approximately 0.1 million shares because the effect would have been anti-dilutive. The computation of diluted net income per common share for 2018 excludes the effect of the potential exercise of restricted stock units to purchase approximately 0.5 million shares because the effect would have been anti-dilutive.

Restructuring and Other

Restructuring and Other	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Restructuring and Other	O. RESTRUCTURING AND OTHER During the year ended December 31, 2020, Teradyne recorded a $19.7 million gain for the decrease in the fair value of the AutoGuide contingent consideration liability, and a $3.5 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by a $4.0 million contract termination settlement charge, $2.5 million of acquisition related compensation and expenses, $2.3 million of severance charges primarily in Industrial Automation, and $1.2 million of other expenses. During the year ended December 31, 2019, Teradyne recorded a $22.2 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by a $3.0 million gain for the increase in the fair value of the AutoGuide contingent consideration, $2.9 million of severance charges related to headcount reductions primarily in Semiconductor Test and Industrial Automation, and $2.5 million for acquisition related expenses and compensation. The remaining accrual for severance of $0.5 million is reflected in the accrued employees’ compensation and withholdings on the balance sheet and is expected to be paid by March 2021.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2020
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. subsidiaries. Benefits under these plans are based on employees’ years of service and compensation. Teradyne’s funding policy is to make contributions to the plans in accordance with local laws and to the extent that such contributions are tax deductible. The assets of these plans consist primarily of fixed income and equity securities. In addition, Teradyne has an unfunded supplemental executive defined benefit plan in the United States to provide retirement benefits in excess of levels allowed by the Employment Retirement Income Security Act (“ERISA”) and the Internal Revenue Code (the “IRC”), as well as unfunded qualified foreign plans. In 2020, Teradyne’s projected benefit obligations increased primarily due to actuarial losses of approximately $27.6 million across all pension plans from decreases in discount rates, and approximately $4.0 million from unfavorable foreign exchange effects for the German plan, partially offset by a transfer of obligations for approximately 115 retiree participants to an insurance company which resulted in a $24.4 million reduction in the projected benefit obligations and pension assets. We also recorded a settlement loss of $0.5 million related to the retiree group annuity transaction. In 2019, Teradyne’s projected benefit obligations increased primarily due to actuarial losses of approximately $29.0 million across all pension plans from decreases in discount rates. The December 31 balances of these defined benefit pension plans assets and obligations are shown below: 2020 2019 United States Foreign United States Foreign (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 203,791 $ 43,952 $ 178,237 $ 39,146 Service cost 1,773 907 1,608 751 Interest cost 5,770 516 7,189 691 Actuarial loss 24,671 2,951 24,447 4,520 Benefits paid (9,844 ) (1,299 ) (7,690 ) (836 ) Retiree annuity purchase (24,379 ) — — — Liability loss due to settlement 451 — — — Non-U.S. currency movement — 3,961 — (320 ) End of year 202,233 50,988 203,791 43,952 Change in plan assets: Fair value of plan assets: Beginning of year 166,932 1,586 144,301 1,400 Actual return on plan assets 23,048 67 27,516 64 Company contributions 3,098 1,079 2,805 923 Benefits paid (9,844 ) (988 ) (7,690 ) (836 ) Retiree annuity purchase (24,379 ) — — — Non-U.S. currency movement — 112 — 35 End of year 158,855 1,856 166,932 1,586 Funded status $ (43,378 ) $ (49,132 ) $ (36,859 ) $ (42,366 ) The following table provides amounts recorded within the account line items of the statements of financial position as of December 31: 2020 2019 United States Foreign United States Foreign (in thousands) Retirement plans assets $ 17,468 $ — $ 18,457 $ — Accrued employees’ compensation and withholdings (3,273 ) (1,019 ) (2,826 ) (922 ) Retirement plans liabilities (57,573 ) (48,113 ) (52,490 ) (41,444 ) Funded status $ (43,378 ) $ (49,132 ) $ (36,859 ) $ (42,366 ) The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2020 2019 United States Foreign United States Foreign (in thousands) Deferred taxes related to prior service cost recognized in other comprehensive income $ 560 $ — $ 560 $ — The accumulated benefit obligation for the United States defined benefit pension plans was $196.7 million and $198.2 million at December 31, 2020 and 2019, respectively. The accumulated benefit obligation for foreign defined benefit pension plans was $46.5 million and $39.9 million at December 31, 2020 and 2019, respectively. Information for pension plans with an accumulated benefit obligation in excess of plan assets as of Decemb e 2020 2019 United States Foreign United States Foreign (in millions) Projected benefit obligation $ 60.8 $ 51.0 $ 55.3 $ 44.0 Accumulated benefit obligation 58.5 46.5 53.2 39.9 Fair value of plan assets — 1.9 — 1.6 Expense For the years ended December 31, 2020, 2019, and 2018, Teradyne’s net periodic pension cost (income) was comprised of the following: 2020 2019 2018 United States Foreign United States Foreign United States Foreign (in thousands) Components of Net Periodic Pension Cost (Income): Service cost $ 1,773 $ 907 $ 1,608 $ 751 $ 2,196 $ 786 Interest cost 5,770 516 7,189 691 8,940 687 Expected return on plan assets (4,840 ) (65 ) (6,042 ) (29 ) (9,049 ) (19 ) Amortization of prior service cost — — — — 58 — Net actuarial loss (gain) 6,463 2,949 2,973 4,485 (4,429 ) 743 Settlement loss 451 — — — 345 — Total net periodic pension cost (income) $ 9,617 $ 4,307 $ 5,728 $ 5,898 $ (1,939 ) $ 2,197 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service cost — — — — (58 ) — Total recognized in other comprehensive income — — — — (58 ) — Total recognized in net periodic pension cost (income) and other comprehensive income $ 9,617 $ 4,307 $ 5,728 $ 5,898 $ (1,997 ) $ 2,197 Weighted Average Assumptions to Determine Net Periodic Pension Cost at January 1: 2020 2019 2018 United States Foreign United States Foreign United States Foreign Discount rate 2.8 % 1.1 % 4.1 % 1.8 % 3.4 % 1.8 % Expected return on plan assets 3.0 3.8 4.3 2.0 4.3 1.5 Salary progression rate 2.6 2.5 2.3 2.5 2.3 2.7 Weighted Average Assumptions to Determine Pension Obligations at December 31: 2020 2019 United States Foreign United States Foreign Discount rate 2.2 % 0.7 % 3.0 % 1.1 % Salary progression rate 2.4 2.3 2.6 2.5 In developing the expected return on plan assets assumption, Teradyne evaluates input from its investment manager and pension consultants, including their forecast of asset class return expectations. Teradyne believes that 3.0% was an appropriate rate to use for fiscal 2020 for the U.S. Qualified Pension Plan (“U.S. Plan”). Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans. The discount rate utilized to determine future pension obligations for the U.S. Plan is based on FTSE Pension Index adjusted for the plan’s expected cash flows and was 2.3% at December 31, 2020, down from 3.10% at December 31, 2019. Plan Assets As of December 31, 2020, the fair value of Teradyne’s pension plans’ assets totaled $160.7 million of which $158.9 million was related to the U.S. Plan and $1.9 million was related to the Taiwan defined benefit pension plan. Substantially all of Teradyne’s pension plans’ assets are held in individual trusts, which were established for the investment of assets of Teradyne’s sponsored retirement plans. The following table provides weighted average pension asset allocation by asset category at December 31, 2020 and 2019: 2020 2019 United States Foreign United States Foreign Fixed income securities 94.0 % — % 94.0 % — % Equity securities 5.0 — 5.0 — Other 1.0 100.0 1.0 100.0 100.0 % 100.0 % 100.0 % 100.0 % The assets of the U.S. Plan are overseen by the Teradyne Fiduciary Committee which is comprised of members of senior management drawn from appropriate diversified levels of the management team. The Fiduciary Committee is responsible for setting the policy that provides the framework for management of the U.S. Plan assets. In accordance with its responsibilities, the Fiduciary Committee meets on a regular basis to review the performance of the U.S. Plan assets and compliance with the investment policy. The policy sets forth an investment structure for managing U.S. Plan assets, including setting the asset allocation ranges, which are expected to provide an appropriate level of overall diversification required to maximize the long-term return on plan assets for a prudent and reasonable level of risk given prevailing market conditions, total investment return over the long term, and preservation of capital, while maintaining sufficient liquidity to pay the benefits of the U.S. Plan. The investment portfolio will not, at any time, have a direct investment in Teradyne stock. It may have indirect investment in Teradyne stock, if one of the funds selected by the investment manager invests in Teradyne stock. In developing the asset allocation ranges, third party asset allocation studies are periodically performed that consider the current and expected positions of the plan assets and funded status. Based on this study and other appropriate information, the Fiduciary Committee establishes asset allocation ranges taking into account acceptable risk targets and associated returns. The investment return objectives are to avoid excessive volatility and produce a rate of return that at least matches the Policy Index identified below. The manager’s investment performance is reviewed at least annually. Results for the total portfolio and for each major category of assets are evaluated in comparison with appropriate market indices and the Policy Index. Teradyne’s U.S. Plan invests primarily in common trust funds. Units held in the common trust funds are valued at the unit price as reported by the investment manager based on the asset value of the underlying investments; underlying investments in equity securities are valued at the last reported sales price, and underlying investments in fixed-income securities are generally valued using methods based upon market transactions for comparable securities. During the years ended December 31, 2020 and December 31, 2019, there were no transfers of pension assets in or out of Level 1, Level 2, and Level 3. The fair value of pension plan assets by asset category and by level at December 31, 2020 and December 31, 2019 were as follows: December 31, 2020 United States Foreign Level 1 Level 2 Level Total Level Level 2 Level Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 127,098 $ — $ 127,098 $ — $ — $ — $ — U.S. government securities — 22,250 — 22,250 — — — — Global equity — 7,925 — 7,925 — — — — Other — — — — — 1,856 — 1,856 Cash and cash equivalents 1,582 — — 1,582 — — — — Total $ 1,582 $ 157,273 $ — $ 158,855 $ — $ 1,856 $ — $ 1,856 December 31, 2019 United States Foreign Level 1 Level 2 Level Total Level Level 2 Level Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 133,792 $ — $ 133,792 $ — $ — $ — $ — U.S. government securities — 23,186 — 23,186 — — — — Global equity — 8,344 — 8,344 — — — — Other — — — — — 1,586 — 1,586 Cash and cash equivalents 1,610 — — 1,610 — — — — Total $ 1,610 $ 165,322 $ — $ 166,932 $ — $ 1,586 $ — $ 1,586 Contributions Teradyne’s funding policy is to make contributions to the plans in accordance with local laws and to the extent that such contributions are tax deductible. During 2020, Teradyne contributed $3.1 million to the U.S. supplemental executive defined benefit pension plan and $1.1 million to certain qualified plans for non-U.S. subsidiaries. During 2019, Teradyne contributed $2.8 million to the U.S. supplemental executive defined benefit pension plan and $0.9 million to certain qualified plans for non-U.S. subsidiaries. In 2021, contributions to the U.S. supplemental executive defined benefit pension plan and certain qualified plans from non-U.S. subsidiaries will be approximately $3.3 million and $1.1 million, respectively. Expected Future Pension Benefit Payments Future benefit payments are expected to be paid as follows: United States Foreign (in thousands) 2021 $ 8,902 $ 1,058 2022 8,782 1,063 2023 9,189 1,313 2024 9,815 1,192 2025 10,374 1,140 2026-2030 54,145 7,053 Postretirement Benefit Plans In addition to receiving pension benefits, U.S. Teradyne employees who meet early retirement eligibility requirements as of their termination dates may participate in Teradyne’s Welfare Plan, which includes medical and dental benefits up to age 65. Death benefits provide a fixed sum to retirees’ survivors and are available to all retirees. Substantially all of Teradyne’s current U.S. employees could become eligible for these benefits, and the existing benefit obligation relates primarily to those employees. The December 31 balances of the postretirement assets and obligations are shown below: 2020 2019 (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 9,003 $ 9,256 Service cost 57 41 Interest cost 240 347 Actuarial loss 421 717 Benefits paid (1,205 ) (1,358 ) End of year 8,515 9,003 Change in plan assets: Fair value of plan assets: Beginning of year — — Company contributions 1,205 1,358 Benefits paid (1,205 ) (1,358 ) End of year — — Funded status $ (8,515 ) $ (9,003 ) The following table provides amounts recorded within the account line items of financial position as of December 31: 2020 2019 (in thousands) Accrued employees’ compensation and withholdings $ (1,161 ) $ (1,231 ) Retirement plans liability (7,354 ) (7,772 ) Funded status $ (8,515 ) $ (9,003 ) The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2020 2019 (in thousands) Prior service credit, before tax $ (49 ) $ (58 ) Deferred taxes (1,686 ) (1,684 ) Total recognized in other comprehensive income, net of tax $ (1,735 ) $ (1,742 ) Expense 2020 2019 2018 (in thousands) Components of Net Periodic Postretirement Benefit Cost (income): Service cost $ 57 $ 41 $ 39 Interest cost 240 347 196 Amortization of prior service credit (9 ) (191 ) (373 ) Net actuarial loss 421 717 25 Special termination benefits — — 3,708 Total net periodic postretirement benefit cost 709 914 3,595 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service credit 9 191 373 Total recognized in other comprehensive income 9 191 373 Total recognized in net periodic postretirement cost and other comprehensive income $ 718 $ 1,105 $ 3,968 Weighted Average Assumptions to Determine Net Periodic Postretirement Benefit Income as of January 1: 2020 2019 2018 Discount rate 3.0 % 4.0 % 3.4 % Initial health care cost trend rate 7.1 7.5 7.9 Ultimate health care cost trend rate 4.5 4.5 4.5 Year in which ultimate health care cost trend rate is reached 2026 2026 2026 2020 2019 2018 Discount rate 2.2 % 3.0 % 4.0 % Initial medical trend 7.3 7.1 7.5 Ultimate health care trend 4.5 4.5 4.5 Medical cost trend rate decrease to ultimate rate in year 2029 2026 2026 Expected Future Benefit Payments Future benefit payments are expected to be paid as follows: Benefit Payments (in thousands) 2021 $ 1,161 2022 961 2023 786 2024 646 2025 533 2026-2030 1,601 The target asset allocation and the index for each asset category for the U.S. Plan, per the investment policy, are as follows: Asset Category: Policy Index: Target Allocation U.S. corporate fixed income Bloomberg Barclays U.S. Corporate A or Better Index 75 % Global equity MSCI World Minimum Volatility Index 5 U.S. government fixed income Bloomberg Barclays U.S. Long Government Bond Index 14 High yield fixed income Bloomberg Barclays U.S. Corporate High Yield 2% Issuer Cap Index 5 Cash Citigroup Three Month U.S. Treasury Bill Index 1

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Stock-Based Compensation	Q. STOCK-BASED COMPENSATION Stock Compensation Plans On July 17, 2019 (the “Retirement Date”), former Chief Financial Officer Gregory Beecher retired as Vice President and Senior Advisor of Teradyne, and Teradyne entered into an agreement (the “Retirement Agreement”) with Mr. Beecher. Under the Retirement Agreement, Mr. Beecher’s unvested time-based restricted stock units and stock options granted prior to 2019 were modified to allow continued vesting; unvested time-based restricted stock units and stock options granted in 2019 were modified to allow continued vesting through January 31, 2023 (the “Non-Competition Period”) in a pro-rated amount based on the number of days that Mr. Beecher was employed during 2019; unvested, performance-based restricted stock units awarded in 2019 will vest on the date the amount of shares underlying the performance-based restricted stock units are determined in a pro-rated amount of shares based on the number of days that Mr. Beecher was employed during 2019; vested options or options that vest during the Non-Competition Period may be exercised for the remainder of the applicable option term. During 2019, Teradyne recorded a stock-based compensation expense of $2.1 million related to the Retirement Agreement. Under Teradyne’s stock compensation plans, Teradyne grants time-based restricted stock units, performance-based restricted stock units, stock options and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Time-based restricted stock unit awards granted to employees vest in equal annual installments over four years. Restricted stock unit awards granted to non-employee directors vest after a one Performance-based restricted stock units (“PRSUs”) granted to Teradyne’s executive officers may have a performance metric based on relative total shareholder return (“TSR”). Teradyne’s three capped at four times the grant date value for grants prior to 2019. 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 to the date described in the retirement provisions below. Compensation expense for executive officers meeting the retirement provisions prior to the grant date is recognized during the year following 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. PRSUs granted to Teradyne’s executive officers may also have a performance metric based on three-year If a PRSU 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 three 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. During 2020, 2019 and 2018, Teradyne granted 0.4 million, 0.8 million and 0.6 million of service-based restricted stock unit awards to employees at a weighted average grant date fair value of $71.31, $37.65, and $45.92, respectively. During 2020, 2019 and 2018, Teradyne granted 0.1 million of service-based restricted stock unit awards to non-employee directors at a weighted average grant date fair value of $66.56, $48.03, and $35.81, respectively. During 2020, 2019 and 2018, Teradyne granted 0.1 million TSR PRSUs, with a grant date fair value of $89.93, $51.51, and $54.85, respectively. The fair value was estimated using the Monte Carlo simulation model with the following assumptions: 2020 2019 2018 Risk-free interest rate 1.5 % 2.6 % 2.2 % Teradyne volatility-historical 34.9 % 31.9 % 26.8 % NYSE Composite Index volatility-historical 11.4 % 11.9 % 12.4 % Dividend yield 0.6 % 1.0 % 0.8 % Expected volatility was based on the historical volatility of Teradyne’s stock and the NYSE Composite Index for each of the 2020, 2019 and 2018 grants 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 each of the grants. Dividend yield was based upon an estimated annual dividend amount of $0.40 per share for 2020 and $0.36 per share for 2019 and 2018, divided by Teradyne’s stock price on the grant date of $72.10 for the 2020 grants, $37.95 for the 2019 grants and $47.70 for the 2018 grants. During 2020, 2019 and 2018, Teradyne granted 0.1 million of PBIT PRSUs with a grant date fair value of $70.94, $36.88 and $46.62, respectively. During 2020, 2019 and 2018, Teradyne granted 0.1 million of service-based stock options to executive officers at a weighted average grant date fair value of $20.93, $10.64, and $12.17, respectively. The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions: 2020 2019 2018 Expected life (years) 5.0 5.0 5.0 Risk-free interest rate 1.5 % 2.5 % 2.4 % Volatility-historical 32.0 % 30.1 % 26.4 % Dividend yield 0.5 % 1.0 % 0.8 % 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 $0.40 per share divided by Teradyne’s stock price on the grant date of $72.61 for the 2020 grants, $37.95 for the 2019 grants and $47.70 for the 2018 grants. Stock compensation plan activity for the years 2020, 2019, and 2018, is as follows: 2020 2019 2018 (in thousands) Restricted Stock Units: Non-vested at January 1 2,269 2,454 3,174 Awarded 616 1,139 790 Vested (1,028 ) (1,237 ) (1,382 ) Forfeited (68 ) (87 ) (128 ) Non-vested at December 31 1,789 2,269 2,454 Stock Options: Outstanding at January 1 319 506 531 Granted 56 102 69 Exercised (159 ) (280 ) (94 ) Forfeited — (7 ) — Expired — (2 ) — Outstanding at December 31 216 319 506 Vested and expected to vest at December 31 216 319 506 Exercisable at December 31 27 85 256 Total shares available for the years 2020, 2019, and 2018: 2020 2019 2018 (in thousands) Shares available: Available for grant at January 1 6,727 7,874 8,605 Options granted (56 ) (102 ) (69 ) Options forfeited — 7 Restricted stock units awarded (616 ) (1,139 ) (790 ) Restricted stock units forfeited 68 87 128 Available for grant at December 31 6,123 6,727 7,874 Weighted average restricted stock unit award date fair value information for the years 2020, 2019, and 2018, is as follows: 2020 2019 2018 Non-vested at January 1 $ 35.58 $ 29.22 $ 21.71 Awarded 72.76 39.08 45.99 Vested 31.53 23.59 20.20 Forfeited 45.36 35.60 24.67 Non-vested at December 31 $ 47.84 $ 35.58 $ 29.22 Restricted stock unit awards aggregate intrinsic value information at December 31 for the years 2020, 2019, and 2018 is as follows: 2020 2019 2018 (in thousands) Vested $ 71,582 $ 46,110 $ 63,688 Outstanding 214,509 154,752 77,015 Expected to vest 210,301 152,374 77,187 Restricted stock units weighted average remaining contractual terms (in years) information at December 31 for the years 2020, 2019, and 2018 is as follows: 2020 2019 2018 Outstanding 0.96 1.02 0.92 Expected to vest 0.96 1.02 0.91 Weighted average stock options exercise price information for the year ended December 31, 2020 is as follows: 2020 Outstanding at January 1 $ 29.91 Options granted 72.61 Options exercised 23.77 Options forfeited — Options cancelled — Outstanding at December 31 45.59 Exercisable at December 31 23.51 The total cash received from employees as a result of employee stock options exercises during the years ended December 31, 2020, 2019, and 2018, was $3.8 million, $3.7 million, and $1.0 million, respectively. In connection with these exercises, the tax benefit realized by Teradyne for the years ended December 31, 2020, 2019, and 2018, was $1.5 million, $2.0 million, and $0.4 million, respectively. Stock option aggregate intrinsic value information for the years ended December 31, 2020, 2019, and 2018 is as follows: 2020 2019 2018 (in thousands) Exercised $ 9,682 $ 9,232 $ 2,960 Outstanding 16,083 12,218 7,359 Vested and expected to vest 13,499 7,701 7,359 Exercisable 2,584 4,517 5,905 Stock options weighted average remaining contractual terms (in years) information at December 31, for the years 2020, 2019, and 2018 is as follows: 2020 2019 2018 Outstanding 4.6 4.2 3.6 Vested and expected to vest 4.9 5.0 3.6 Exercisable 2.5 2.1 2.4 As of December 31, 2020, total unrecognized expense related to non-vested restricted stock unit awards and stock options was $44 million and is expected to be recognized over a weighted average period of 2.4 years. Employee Stock Purchase Plan Under the ESPP, eligible employees may purchase shares of common stock through regular payroll deductions of up to 10% of their compensation, to a maximum of shares with a fair market value of $25,000 per calendar year, not to exceed 6,000 shares. Under the plan, the price paid for the common stock is equal to 85% of the stock price on the last business day of the six-month purchase period. In July 2020, 0.2 million shares of common stock were issued to employees who participated in the plan during the first half of 2020 at the price of $71.83 per share. In January 2021, Teradyne issued 0.1 million shares of common stock to employees who participated in the plan during the second half of 2020 at the price of $101.91 per share. In July 2019, 0.3 million shares of common stock were issued to employees who participated in the plan during the first half of 2019 at the price of $40.72 per share. In January 2020, Teradyne issued 0.2 million shares of common stock to employees who participated in the plan during the second half of 2019 at the price of $57.96 per share. In July 2018, 0.3 million shares of common stock were issued to employees who participated in the plan during the first half of 2018 at the price of $32.36 per share. In January 2019, Teradyne issued 0.4 million shares of common stock to employees who participated in the plan during the second half of 2018 at the price of $26.67 per share. As of December 31, 2020, there were 1.4 million shares available for grant under the ESPP. The following table provides the effect to income from operations for recording stock-based compensation for the years ended December 31, 2020, 2019, and 2018: 2020 2019 2018 (in thousands) Cost of revenues $ 4,227 $ 3,480 $ 3,129 Engineering and development 12,039 9,913 9,181 Selling and administrative 28,640 24,504 21,267 Stock-based compensation 44,906 37,897 33,577 Income tax benefit (13,060 ) (8,360 ) (12,036 ) Total stock-based compensation expense after income taxes $ 31,846 $ 29,537 $ 21,541

Savings Plan

Savings Plan	12 Months Ended
	Dec. 31, 2020
Savings Plan	R. SAVINGS PLAN Teradyne sponsors a defined contribution employee retirement savings plan (“Savings Plan”) covering substantially all U.S. employees. Under the Savings Plan, employees may contribute up to 20% of their compensation (subject to Internal Revenue Service limitations). The Savings Plan provides for a discretionary employer match that is determined each year. In 2020, 2019 and 2018, Teradyne matched 100% of eligible employee contributions up to 4% of their compensation for employees not accruing benefits in the U.S. Qualified Pension Plan. There was no match for employees still actively accruing benefits in the U.S. Qualified Pension Plan. Teradyne’s contributions vest 25% per year for the first four years of employment, and contributions for those employees with In addition, Teradyne sponsors an unfunded U.S. Supplemental Savings Plan to provide savings benefits in excess of those allowed by the Employee Retirement Income Security Act of 1974 and the Internal Revenue Code. The provisions of this plan are the same as the Savings Plan. The liability for the U.S. Supplemental Savings Plan at December 31, 2020 and 2019, was $38.0 million and $32.7 million, respectively, and is included in retirement plan liabilities. Teradyne contributes to defined contributions savings plans for its foreign employees. Under Teradyne’s savings plans, amounts charged to the statements of operations for the years ended December 31, 2020, 2019, and 2018 were $21.7 million, $20.9 million, and $19.4 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Taxes	S. INCOME TAXES The components of income (loss) before income taxes and the provision (benefit) for income taxes as shown in the consolidated statements of operations were as follows: 2020 2019 2018 (in thousands) Income before income taxes: U.S. $ 312,153 $ 192,442 $ 189,691 Non-U.S. 588,862 333,330 278,110 $ 901,015 $ 525,772 $ 467,801 Provision (benefit) for income taxes: Current: U.S. Federal $ 58,678 $ 19,297 $ (59,122 ) Non-U.S. 75,193 52,810 45,083 State (1,315 ) (4,347 ) 1,721 132,556 67,760 (12,318 ) Deferred: U.S. Federal (12,604 ) (4,522 ) 29,252 Non-U.S. (5,127 ) (8,007 ) (1,243 ) State 2,043 3,073 331 (15,688 ) (9,456 ) 28,340 Total provision for income taxes: $ 116,868 $ 58,304 $ 16,022 Income tax expense for 2020, 2019 and 2018 totaled $116.9 million, $58.3 million, and $16.0 million, respectively. The effective tax rate for 2020, 2019 and 2018 was 13.0%, 11.1% and 3.4%, respectively. On December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act of 2017 (the “Tax Reform Act”), making significant changes to the Internal Revenue Code. The Tax Reform Act has significant direct and indirect implications for accounting for income taxes under ASC 740, “Accounting for Income Taxes” some of which could not be calculated with precision until further clarification and guidance was made available from tax authorities, regulatory bodies or the FASB. In light of this uncertainty, on December 22, 2017 the SEC issued Staff Accounting Bulletin (“SAB”) No. 118, “Income Tax Accounting Implications of the Tax Cuts and Jobs Act,” to address uncertainty in the application of U.S. GAAP when the registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. In accordance with SAB 118, Teradyne recorded $186.0 million of additional income tax expense in the fourth quarter of 2017 which represented Teradyne’s best estimate of the impact of the Tax Reform Act in accordance with Teradyne’s understanding of the Tax Reform Act and available guidance as of that date. The $186.0 million was primarily composed of expense of $161.0 million related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings, $33.6 million of expense related to the remeasurement of certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, and a benefit of $10.3 million associated with the impact of correlative adjustments on uncertain tax positions. In accordance with the requirements of SAB 118, in the fourth quarter of 2018, Teradyne completed its analysis of the effect of the Tax Reform Act based on the application of the most recently available guidance as of December 31, 2018 and recorded $49.5 Teradyne has made an accounting policy election to account for global intangible low-taxed income (“GILTI”) as a component of tax expense in the period in which Teradyne is subject to the rules and therefore did not provide any deferred tax impacts of GILTI in its consolidated financial statements. The increase in the effective tax rate from 2019 to 2020 is primarily attributable to a reduction in the benefit from releases of reserves for uncertain tax positions and a reduction in the benefit from foreign tax credits. These increases in expense were partially offset by a decrease in the transition tax on the mandatory deemed repatriation of foreign earnings and shift in the geographic distribution of income, which increases the income subject to taxation in lower tax rate jurisdictions relative to higher tax rate jurisdictions. On July 27, 2015, in Altera Corp. (“Altera”) v. Commissioner, the U.S. Tax Court issued an opinion invalidating the regulations relating to the treatment of stock-based compensation expense in an intercompany cost-sharing arrangement. A final decision was issued by the Tax Court in December 2015. The IRS appealed the decision in June 2016. On July 24, 2018, the U.S. Court of Appeals for the Ninth Circuit (“Ninth Circuit”) issued a decision that was subsequently withdrawn and a reconstituted panel conferred on the appeal. On June 7, 2019, the Ninth Circuit upheld the cost-sharing regulations. On November 12, 2019 the Ninth Circuit denied Altera’s petition for rehearing of its case. Altera’s application for certiorari to the Supreme Court was declined on June 22, 2020. In the fourth quarter of 2019 and 2020, Teradyne recognized tax expense of approximately $6.3 million and $2.3 million, respectively, related to the inclusion of stock-based compensation in its intercompany cost-sharing arrangement. The increase in the effective tax rate from 2018 to 2019 is primarily attributable to increases in expense associated with GILTI and the transition tax on the mandatory deemed repatriation of foreign earnings. These increases in expense were partially offset by increased benefit from the U.S. foreign derived intangible income deduction, foreign tax credits and a net reduction of reserves for uncertain tax positions. A reconciliation of the effective tax rate for the years 2020, 2019 and 2018 is as follows: 2020 2019 2018 U.S. statutory federal tax rate 21.0 % 21.0 % 21.0 % U.S. global intangible low-taxed income 5.7 6.2 0.3 State income taxes, net of federal tax benefit 0.3 0.5 0.1 Foreign taxes (5.6 ) (4.0 ) (2.0 ) Foreign tax credits (4.8 ) (5.9 ) (2.2 ) U.S. foreign derived intangible income (2.2 ) (2.6 ) (1.8 ) U.S. research and development credit (1.3 ) (1.8 ) (2.2 ) Equity compensation (0.6 ) (0.7 ) (1.2 ) Uncertain tax positions (0.1 ) (4.3 ) 1.0 U.S. transition tax — 1.9 (10.5 ) Impact of rate change on deferred taxes — — 0.3 Other, net 0.6 0.8 0.6 13.0 % 11.1 % 3.4 % Teradyne qualifies for a tax holiday in Singapore by fulfilling the requirements of an agreement with the Singapore Economic Development Board under which certain headcount and spending requirements must be met. The tax savings attributable to the Singapore tax holiday for the years ended December 31, 2020, 2019 and 2018 were $29.9 million or $0.16 per diluted share, $15.1 million or $0.08 per diluted share and $11.9 million or $0.06 per diluted share, respectively. In November 2020, Teradyne entered into an agreement with the Singapore Economic Development Board which extended our Singapore tax holiday under substantially similar terms to the agreement which expired on December 31, 2020. The new tax holiday is scheduled to expire on December 31, 2025. Significant components of Teradyne’s deferred tax assets (liabilities) as of December 31, 2020 and 2019 were as follows: 2020 2019 (in thousands) Deferred tax assets: Tax credits $ 87,595 $ 79,480 Accruals 33,156 25,424 Pension liabilities 28,348 24,459 Inventory valuations 18,427 18,572 Lease liability 12,627 13,093 Deferred revenue 9,235 7,622 Equity compensation 6,543 7,042 Vacation accrual 5,890 4,768 Investment impairment 3,292 3,292 Net operating loss carryforwards 1,823 2,705 Other 626 187 Gross deferred tax assets 207,562 186,644 Less: valuation allowance (84,962 ) (77,177 ) Total deferred tax assets $ 122,600 $ 109,467 Deferred tax liabilities: Depreciation $ (14,525 ) $ (18,238 ) Intangible assets (12,726 ) (16,705 ) Right of use assets (10,688 ) (11,197 ) Contingent consideration (3,515 ) — Marketable securities (3,344 ) (1,601 ) Other (710 ) (611 ) Total deferred tax liabilities $ (45,508 ) $ (48,352 ) Net deferred assets $ 77,092 $ 61,115 At December 31, 2020, Teradyne had operating loss carryforwards that expire in the following years: State Operating Loss Carryforwards Foreign Operating Loss Carryforwards (in thousands) 2021 $ 333 $ — 2022 2,203 — 2023 3,368 — 2024 812 — 2025 191 — 2026-2030 7,452 — 2031-2035 2,147 68 Beyond 2035 73 — Non-expiring 870 3,923 Total $ 17,449 $ 3,991 Teradyne has approximately $116.3 million of tax credit carryforwards including federal business tax credits of approximately $1.9 million which expire in 2028 through 2030, and state tax credits of $114.3 million, of which $63.8 million do not expire and the remainder expires in the years 2021 through 2040. Teradyne’s gross unrecognized tax benefits for the years ended December 31, 2020, 2019 and 2018 were as follows: 2020 2019 2018 (in thousands) Beginning balance as of January 1 $ 21,180 $ 43,395 $ 36,263 Additions: Tax positions for current year 1,082 1,322 4,716 Tax positions for prior years 66 8,043 2,626 Reductions: Tax positions for prior years (2,989 ) (31,397 ) (153 ) Expiration of statutes (1,436 ) (183 ) (57 ) Ending balance as of December 31 $ 17,903 $ 21,180 $ 43,395 Current year additions relate to federal and state research credits. Prior year additions primarily relate to stock-based compensation. Prior year reductions are primarily composed of federal and state reserves related to transfer pricing and research credits and resulted from the completion of the 2015 U.S. federal audit in the first quarter of 2019. Of the $17.9 million of unrecognized tax benefits as of December 31, 2020, $12.0 million would impact the consolidated income tax rate if ultimately recognized. The remaining $5.9 million would impact deferred taxes if recognized. As of December 31, 2020, Teradyne estimates that it is reasonably possible that the balance of unrecognized tax benefits may decrease approximately $1.6 million in the next twelve months as a result of a lapse of statutes of limitation. The estimated decrease relates to loss carryforwards, research credits and U.S. manufacturing activities deductions. Teradyne records all interest and penalties related to income taxes as a component of income tax expense. Accrued interest and penalties related to income tax items at December 31, 2020 and 2019 amounted to $1.2 million and $1.4 million, respectively. For the years ended December 31, 2020, 2019 and 2018, benefit of $0.2 million, expense of $1.1 million and benefit of $0.1 million, respectively, was recorded for interest and penalties related to income tax items. Teradyne is subject to U.S. federal income tax, as well as income tax in multiple state, local and foreign jurisdictions. As of December 31, 2020, all material state and local income tax matters have been concluded through 2015, all material federal income tax matters have been concluded through 2016 and all material foreign income tax matters have been concluded through 2012. However, in some jurisdictions, including the United States, operating losses and tax credits may be subject to adjustment until such time as they are utilized and the year of utilization is closed to adjustment. As of December 31, 2020, Teradyne is not permanently reinvested with respect to the unremitted earnings of non-U.S. subsidiaries to the extent that those earnings exceed local statutory and operational requirements. Remittance of those earnings is not expected to result in material income tax.

Operating Segment, Geographic a

Operating Segment, Geographic and Significant Customer Information	12 Months Ended
	Dec. 31, 2020
Operating Segment, Geographic and Significant Customer Information	T. OPERATING SEGMENT, GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION Teradyne has four reportable segments (Semiconductor Test, System Test, Wireless Test and Industrial Automation). Each of the reportable segment represents an individual operating segment. On September 15, 2020, Teradyne announced the appointment of Gregory Smith as President of Teradyne’s Industrial Automation reportable segment effective October 1, 2020. With the appointment of Gregory Smith, the Industrial Automation reportable segment is considered one operating segment and one reporting unit. 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 storage and system level test, defense/aerospace instrumentation test, and circuit-board test. The Wireless Test segment includes operations related to the design, manufacturing and marketing of wireless test products and services. The Industrial Automation segment includes operations related to the design, manufacturing and marketing of collaborative robotic arms, autonomous mobile robots and advanced robotic control software. 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 are the same as those described in Note B: “Accounting Policies.” Segment information for the years ended December 31, 2020, 2019, and 2018 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate and Other Consolidated (in thousands) 2020 Revenues $ 2,259,597 $ 409,729 $ 279,731 $ 173,016 $ (604 ) $ 3,121,469 Income (loss) before taxes (1)(2) 739,695 152,092 (24,019 ) 41,950 (8,703 ) 901,015 Total assets (3) 1,070,378 138,295 712,936 106,273 1,624,464 3,652,346 Property additions 168,055 3,092 8,899 4,931 — 184,977 Depreciation and amortization expense 64,998 3,426 36,242 6,258 15,819 126,743 2019 Revenues $ 1,552,571 $ 287,455 $ 298,139 $ 157,315 $ (515 ) $ 2,294,965 Income (loss) before taxes (1)(2) 416,973 93,543 (5,916 ) 35,585 (14,413 ) 525,772 Total assets (3) 784,808 131,428 671,559 97,299 1,101,920 2,787,014 Property additions 112,145 3,059 9,076 10,362 — 134,642 Depreciation and amortization expense 59,197 5,518 40,904 5,365 9,671 120,655 2018 Revenues $ 1,492,417 $ 216,132 $ 261,452 $ 132,006 $ (1,205 ) $ 2,100,802 Income (loss) before taxes (1)(2) 397,645 48,857 7,670 29,052 (15,423 ) 467,801 Total assets (3) 669,452 88,098 607,502 77,570 1,263,984 2,706,606 Property additions 94,496 3,469 11,188 5,226 — 114,379 Depreciation and amortization expense 58,095 6,430 36,755 5,328 6,616 113,224 (1) Included in Corporate and Other are: contingent consideration adjustments, investment impairment, pension and postretirement plans actuarial gains (losses), severance charges, interest income, interest expense, net foreign exchange gains (losses), intercompany eliminations and acquisition related charges. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, and inventory charges. (3) Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets. Included in each segment are charges and credits in the following line items in the statements of operations: For the Year Ended December 31, 2020 2019 2018 (in thousands) Semiconductor Test: Cost of revenues—inventory charge $ 11,013 $ 8,731 $ 6,822 Contract termination settlement fee 4,000 — — Restructuring and other—employee severance — 1,277 8,429 System Test: Cost of revenues—inventory charge $ 887 $ 2,000 $ 1,175 Industrial Automation: Restructuring and other—acquisition related expenses and compensation $ 985 $ 741 $ 1,163 Cost of revenues—inventory charge 834 508 680 Restructuring and other—employee severance 1,584 796 — Wireless: Cost of revenues—inventory charge $ 4,800 $ 4,005 $ 2,565 Corporate and Other: Restructuring and other—AutoGuide contingent consideration adjustment $ (19,724 ) $ 2,976 $ — Restructuring and other—MiR contingent consideration adjustment (3,546 ) (22,199 ) 17,666 Restructuring and other—acquisition related expenses and compensation 1,728 1,765 3,422 Other (income) expense, net—investment impairment charge — 15,000 — Selling and administrative—equity modification charge 766 2,108 — Restructuring and other—Universal Robots contingent consideration adjustment — — (16,679 ) Information as to Teradyne’s revenues by country is as follows: 2020 2019 2018 (in thousands) Revenues from customers (1): Taiwan $ 1,178,068 $ 485,681 $ 516,322 China 465,722 514,327 348,942 Korea 391,571 239,504 163,224 United States 321,674 333,059 282,869 Europe 205,587 219,015 223,207 Japan 143,983 175,322 158,281 Thailand 138,787 87,503 59,184 Singapore 76,460 84,111 108,618 Philippines 68,887 54,560 77,996 Malaysia 56,096 58,200 122,797 Rest of the World 74,634 43,683 39,362 $ 3,121,469 $ 2,294,965 $ 2,100,802 (1) Revenues attributable to a country are based on location of customer site. In 2020, revenues from Taiwan Semiconductor Manufacturing Company Ltd., a customer of Teradyne’s Semiconductor Test segment, accounted for 15% of Teradyne’s consolidated revenues. In 2019 and 2018, no single direct customer accounted for more than 10% of Teradyne’s consolidated revenues. Teradyne estimates consolidated revenues driven by one OEM customer, combining direct sales to that customer with sales to the customer’s OSATs (which include Taiwan Semiconductor Manufacturing Company Ltd.), accounted for estimates consolidated revenues driven by Huawei Technologies Co., Ltd. (“Huawei”), combining direct sales to that customer with sales to the customer’s OSATs, accounted for approximately 3% and 11% of its consolidated revenues in 2020 and 2019, respectively. Long-lived assets by geographic area: United States Foreign(1) Total (in thousands) December 31, 2020 $ 291,234 $ 158,135 $ 449,369 December 31, 2019 $ 252,812 $ 124,943 $ 377,755 (1) As of December 31, 2020 and 2019, long-lived assets attributable to Singapore were $62.5 million and $35.2 million, respectively.

Stock Repurchase Program

Stock Repurchase Program	12 Months Ended
	Dec. 31, 2020
Stock Repurchase Program	U. STOCK REPURCHASE PROGRAM In 2018, Teradyne repurchased 21.6 million shares of common stock for $823.5 million at an average price per share of $38.06. In 2019, Teradyne repurchased 10.9 million shares of common stock for $500.0 million at an average price per share of $45.89. The cumulative repurchases as of December 31, 2019, for the 2018 stock repurchase program, totaled 32.5 million shares of common stock for $1,323.0 million at an average price per share of $40.68. In January 2020, Teradyne’s Board of Directors cancelled the January 2018 repurchase program and approved a new stock repurchase program for up to $1.0 billion of common stock. On April 1, 2020, Teradyne suspended its share repurchase program. In 2020, Teradyne repurchased 1.5 million shares of common stock for $88.5 million at an average price of $58.33 per share. In January 2021, Teradyne’s Board of Directors cancelled the January 2020 repurchase program and approved a new repurchase program for up to $2.0 billion of common stock. Teradyne intends to repurchase a minimum of $600 million in 2021.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events	V. SUBSEQUENT EVENTS In January 2021, Teradyne’s Board of Directors declared a quarterly cash dividend of $0.10 per share to be paid on March 19, 2021 to shareholders of record as of February 19, 2021. 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.

Supplementaryd Information

Supplementaryd Information	12 Months Ended
	Dec. 31, 2020
Supplementary Information	SUPPLEMENTARY INFORMATION (Unaudited) The following sets forth certain unaudited consolidated quarterly statements of operations data for each of Teradyne’s last eight quarters. In management’s opinion, this quarterly information reflects all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement for the periods presented. Such quarterly results are not necessarily indicative of future results of operations and should be read in conjunction with the audited consolidated financial statements of Teradyne and the notes thereto included elsewhere herein. 2020 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (2)(5) (3)(5) (4)(5) (in thousands, except per share amounts) Revenues: Products $ 610,906 $ 734,630 $ 697,745 $ 647,625 Services 93,449 104,031 121,739 111,343 Total revenues 704,355 838,661 819,484 758,968 Cost of revenues: Cost of products 259,996 322,732 300,174 274,574 Cost of services 38,809 44,456 60,382 34,605 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 298,805 367,188 360,556 309,179 Gross profit 405,550 471,473 458,928 449,789 Operating expenses: Selling and administrative 111,388 113,259 115,840 124,279 Engineering and development 85,159 94,102 94,909 100,795 Acquired intangible assets amortization 9,891 8,941 6,219 5,752 Restructuring and other (7,606 ) 37,222 (27,701 ) (15,117 ) Total operating expenses 198,832 253,524 189,267 215,709 Income from operations 206,718 217,949 269,661 234,080 Non-operating (income) expense: Interest income (2,751 ) (1,368 ) (1,071 ) (793 ) Interest expense 5,551 6,043 6,237 6,351 Other (income) expense, net 6,849 (4,017 ) 764 5,597 Income before income taxes 197,069 217,291 263,731 222,925 Income tax provision 20,878 28,383 41,013 26,595 Net income $ 176,191 $ 188,908 $ 222,718 $ 196,330 Net income per common share—basic $ 1.06 $ 1.14 $ 1.34 $ 1.18 Net income per common share—diluted $ 0.97 $ 1.05 $ 1.21 $ 1.05 Cash dividend declared per common share $ 0.10 $ 0.10 $ 0.10 $ 0.10 (1) Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test. (2) Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability. (3) Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation. (4) Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation. (5) Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy. 2019 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (2) (3) (4)(5)(6) (in thousands, except per share amounts) Revenues: Products $ 393,442 $ 457,511 $ 488,170 $ 548,552 Services 100,657 106,667 93,868 106,098 Total revenues 494,099 564,178 582,038 654,650 Cost of revenues: Cost of products 165,368 193,299 197,196 226,184 Cost of services 41,096 46,961 39,804 45,228 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 206,464 240,260 237,000 271,412 Gross profit 287,635 323,918 345,038 383,238 Operating expenses: Selling and administrative 102,013 108,811 109,166 117,092 Engineering and development 76,791 81,434 77,804 86,794 Acquired intangible assets amortization 10,634 10,083 9,647 9,784 Restructuring and other 5,112 (10,404 ) (6,500 ) (2,088 ) Total operating expenses 194,550 189,924 190,117 211,582 Income from operations 93,085 133,994 154,921 171,656 Non-operating (income) expense: Interest income (4,989 ) (4,384 ) (4,433 ) (3,185 ) Interest expense 5,520 5,800 5,463 5,441 Other (income) expense, net (1,425 ) 1,401 2,158 20,514 Income before income taxes 93,979 131,177 151,733 148,886 Income tax provision (benefit) (15,159 ) 33,780 15,873 23,811 Net income $ 109,138 $ 97,397 $ 135,860 $ 125,075 Net income per common share—basic $ 0.63 $ 0.57 $ 0.80 $ 0.75 Net income per common share—diluted $ 0.62 $ 0.55 $ 0.75 $ 0.69 Cash dividend declared per common share $ 0.09 $ 0.09 $ 0.09 $ 0.09 (1) Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges. (2) Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation. (3) Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation. (4) Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation. (5) Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy. (6) Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
Valuation and Qualifying Accounts	TERADYNE, INC. SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS Column A Column B Column C Column D Column E Column F Description Balance at Beginning of Period Additions Charged to Cost and Expenses Other Deductions Balance at End of Period (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Accounts receivable: 2020 Allowance for doubtful account $ 1,736 $ 356 $ 32 $ 90 $ 2,034 2019 Allowance for doubtful account $ 1,673 $ 87 $ 28 $ 52 $ 1,736 2018 Allowance for doubtful account $ 2,219 $ — $ 20 $ 566 $ 1,673 Column A Column B Column C Column D Column E Column F Description Balance at Beginning of Period Additions Charged to Cost and Expenses Other Deductions Balance at End of Period (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Inventory: 2020 Inventory reserve $ 103,556 $ 17,534 $ (521 ) $ 9,982 $ 110,587 2019 Inventory reserve $ 100,779 $ 15,244 $ (85 ) $ 12,382 $ 103,556 2018 Inventory reserve $ 102,896 $ 11,242 $ 368 $ 13,727 $ 100,779 Column A Column B Column C Column D Column E Column F Description Balance at Beginning of Period Additions Charged to Cost and Expenses Other Deductions Balance at End of Period (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Deferred taxes: 2020 Valuation allowance $ 77,177 $ 7,785 $ — $ — $ 84,962 2019 Valuation allowance $ 69,852 $ 7,325 $ — $ — $ 77,177 2018 Valuation allowance $ 63,919 $ 6,333 $ — $ 400 $ 69,852

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Basis of Presentation	Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going basis, management evaluates its estimates, including those related to inventories, investments, goodwill, intangible and other long-lived assets, accounts receivable, income taxes, deferred tax assets and liabilities, pensions, warranties, contingent consideration liabilities, and loss contingencies. Management bases its estimates on historical experience and on appropriate and customary assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Due to the COVID-19 pandemic, there has been uncertainty and disruption in the global economy and our markets. Management is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of February 22, 2021, the date of issuance of this Annual Report on Form 10-K. These estimates may change, as new events occur and additional information is obtained. Actual results may differ significantly from these estimates under different assumptions or conditions.
Preparation of Financial Statements and Use of Estimates	Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going basis, management evaluates its estimates, including those related to inventories, investments, goodwill, intangible and other long-lived assets, accounts receivable, income taxes, deferred tax assets and liabilities, pensions, warranties, contingent consideration liabilities, and loss contingencies. Management bases its estimates on historical experience and on appropriate and customary assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Due to the COVID-19 pandemic, there has been uncertainty and disruption in the global economy and our markets. Management is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of February 22, 2021, the date of issuance of this Annual Report on Form 10-K. These estimates may change, as new events occur and additional information is obtained. Actual results may differ significantly from these estimates under different assumptions or conditions.
Revenue Recognition	Revenue Recognition Revenue from Contracts with Customers Teradyne adopted Accounting Standard Codification (“ASC”) 606 “Revenue from Contracts with Customers” on January 1, 2018 using the modified retrospective method for all contracts not completed as of the date of adoption. 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. • 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. • Teradyne periodically enters into contracts with customers in which a customer may purchase a combination of goods and 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. • 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. • 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. • 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 that 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. Performance Obligations Products Teradyne products consist 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, wireless test systems and industrial automation products. Teradyne’s hardware is recognized at a point in time upon transfer of control to the customer. Services Teradyne services consist of extended warranties, training and application support, service agreements, post contract customer support (“PCS”) and replacement parts. Each service is recognized based on relative standalone selling price. Extended warranty, training and support, service agreements and PCS are recognized over time based on the period of service. Replacement parts are recognized at a point in time upon transfer of control to the customer. Teradyne does not allow customer returns or provide refunds to customers for any products or services. Teradyne products include 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. Cost related to warranty are included in cost of revenues when product revenues are recognized. As of December 31, 2020 and 2019, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2020 2019 (in thousands) Maintenance, service and training $ 77,654 $ 63,815 Customer advances, undelivered elements and other 63,438 56,358 Extended warranty 51,929 30,677 Total deferred revenue and customer advances $ 193,021 $ 150,850
Product Warranty	Product Warranty Teradyne generally provides a one-year warranty on its products, commencing upon installation, acceptance or shipment. A provision is recorded upon revenue recognition to cost of revenues for estimated warranty expense based on historical experience. Related costs are charged to the warranty accrual as incurred.The balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2017 $ 8,200 Acquisition 41 Accruals for warranties issued during the period 13,045 Accruals related to pre-existing warranties 921 Settlements made during the period (14,298 ) Balance at December 31, 2018 7,909 Acquisition 14 Accruals for warranties issued during the period 14,106 Accruals related to pre-existing warranties 4,026 Settlements made during the period (17,059 ) Balance at December 31, 2019 8,996 Accruals for warranties issued during the period 28,490 Accruals related to pre-existing warranties 821 Settlements made during the period (21,674 ) Balance at December 31, 2020 $ 16,633 When Teradyne receives revenue for extended warranties, beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2017 $ 24,438 Deferral of new extended warranty revenue 23,753 Recognition of extended warranty deferred revenue (20,769 ) Balance at December 31, 2018 27,422 Deferral of new extended warranty revenue 23,271 Recognition of extended warranty deferred revenue (20,016 ) Balance at December 31, 2019 30,677 Deferral of new extended warranty revenue 41,694 Recognition of extended warranty deferred revenue (20,442 ) Balance at December 31, 2020 $ 51,929
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not bear interest. Teradyne maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Estimated allowances for doubtful accounts are reviewed periodically taking into account the customer’s recent payment history, the customer’s current financial statements and other information regarding the customer’s credit worthiness. Account balances are written off against the allowance when it is determined the receivable will not be recovered. Teradyne sells certain trade accounts receivables on a non-recourse basis to third-party financial institutions pursuant to factoring agreements. Teradyne accounts for these transactions as sales of receivables and presents cash proceeds as a cash provided by operating activities in the consolidated statements of cash flows. Total trade accounts receivable sold under the factoring agreements were $131.1 million and $143.6 million during 2020 and 2019, respectively. Factoring fees for the sales of receivables are recorded in interest expense and are not material.
Inventories	Inventories Inventories are stated at the lower of cost (first-in, first-out basis) or net realizable value. On a quarterly basis, Teradyne uses consistent methodologies to evaluate all inventories for net realizable value. Teradyne records a provision for both excess and obsolete inventory when such write-downs or write-offs are identified through the quarterly review process. The inventory valuation is based upon assumptions about future demand, product mix and possible alternative uses.
Investments	Investments Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, “ Investments—Debt and Equity Securities • The length of time and the extent to which the market value has been less than cost; • The financial condition and near-term prospects of the issuer; and • The intent and ability to retain the investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. Teradyne uses the market and income approach techniques to value its financial instruments and there were no changes in valuation techniques during the twelve months ended December 31, 2020 and 2019. As defined in ASC 820-10, “ Fair Value Measurements and Disclosures, Level 1: Quoted prices in active markets for identical assets as of the reporting date; Level 2: Inputs other than Level 1, that are observable either directly or indirectly as of the reporting date. For example, a common approach for valuing fixed income securities is the use of matrix pricing. Matrix pricing is a mathematical technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, and 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. In accordance with ASC 820-10, Teradyne measures its debt and equity investments at fair value. Teradyne’s debt investments are classified as Level 2, and equity investments are classified as Level 1. Acquisition-related contingent consideration is classified as Level 3. Teradyne determines the fair value of acquisition-related contingent consideration using a Monte Carlo simulation model. Assumptions utilized in the model include forecasted revenues, revenue volatility, earnings before interest and taxes, and discount rate.
Financial Assets and Financial Liabilities	Financial Assets and Financial Liabilities In January 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-01, “ Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities
Prepayments	Prepayments Prepayments consist of the following and are included in prepayments and other current assets on the balance sheet: 2020 2019 (in thousands) Contract manufacturer and supplier prepayments $ 212,286 $ 143,392 Prepaid taxes 9,361 8,046 Prepaid maintenance and other services 13,116 8,503 Other prepayments 15,329 16,753 Total prepayments $ 250,092 $ 176,694
Retirement and Postretirement Plans	Retirement and Postretirement Plans Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans.
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
Goodwill, Intangible and Long-Lived Assets	Goodwill, Intangible and Long-Lived Assets Teradyne accounts for goodwill and intangible assets in accordance with ASC 350-10, “ Intangibles-Goodwill and Other. of December 31, on a reporting unit basis, or more frequently when events and circumstances occur indicating that the recorded goodwill may be impaired. In accordance with ASC 350-10, Teradyne has the option to perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If Teradyne determines this is the case, Teradyne is required to perform a quantitative goodwill impairment test to identify potential goodwill impairment and measure the amount of goodwill impairment loss to be recognized. If Teradyne determines that it is more likely than not that the fair value of the reporting unit is greater than its carrying amounts, a quantitative goodwill impairment test is not required. In accordance with ASC 360-10, “ Impairment or Disposal of Long-Lived Assets,
Business Combination	Business Combination Teradyne recognizes the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values at the date of acquisition. The fair value of identifiable intangible assets is based on detailed cash flows valuations that use information and assumptions provided by management. Teradyne estimates the fair value of contingent consideration at the time of the acquisition using all pertinent information known to us at the time to assess the probability of payment of contingent amounts or through the use of a Monte Carlo simulation model. Teradyne allocates any excess purchase price over the fair value of the net tangible and intangible assets acquired and liabilities assumed to goodwill. The assumptions used in the valuations for our acquisitions may differ materially from actual results depending on performance of the acquired businesses and other factors. While Teradyne believes the assumptions used were appropriate, different assumptions in the valuation of assets acquired and liabilities assumed could have a material impact on the timing and extent of impact on our statements of operations. Goodwill is assigned to reporting units as of the date of the related acquisition.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost and depreciated over the estimated useful lives of the assets. Leasehold improvements and major renewals are capitalized and included in property, plant and equipment accounts, while expenditures for maintenance and repairs and minor renewals are charged to expense. When assets are retired, the assets and related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations. Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 Building improvements 5 Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 Machinery, equipment and software 3 Test systems manufactured internally are used by Teradyne for customer evaluations and manufacturing and support of its customers. Teradyne depreciates the test systems manufactured internally over a six-year internally manufactured test equipment to customers. Upon the sale of an internally manufactured test system, the net book value of the system is transferred to inventory and expensed as cost of revenues. The net book value of internally manufactured test systems sold in the years ended December 31, 2020, 2019, and 2018 was $7.3 million, $5.0 million, and $3.8 million, respectively.
Leases	Leases Teradyne adopted Accounting Standards Update (“ASU”) 2016-02, “ Leases (Topic 842) Leases (Topic 842): Targeted Improvements Under ASC 842, a contract is or contains a lease when Teradyne has the right to control the use of an identified asset. Teradyne determines if an arrangement is a lease at inception of the contract, which is the date on which the terms of the contract are agreed to and the agreement creates enforceable rights and obligations. The commencement date of the lease is the date that the lessor makes an underlying asset available for use by Teradyne. As of December 31, 2020, Teradyne does not have material leases that have not yet commenced. Teradyne determines if the lease is an operating or finance lease at the lease commencement date based upon the terms of the lease and the nature of the asset. The lease term used to calculate the lease liability includes options to extend or terminate the lease when it is reasonably certain that the option will be exercised. For leases commencing after January 1, 2019, the lease liability is measured at the present value of future lease payments, discounted using the discount rate for the lease at the commencement date. As Teradyne is typically unable to determine the implicit rate, Teradyne uses an incremental borrowing rate based on the lease term and economic environment at commencement date. Teradyne initially measures payments based on an index by using the applicable rate at lease commencement. Variable payments that do not depend on an index are not included in the lease liability and are recognized as they are incurred. The ROU asset is initially measured as the amount of lease liability, adjusted for any initial lease costs, prepaid lease payments, and reduced by any lease incentives. Teradyne’s contracts often include non-lease components such as common area maintenance. Teradyne elected the practical expedient to account for the lease and non-lease components as a single lease component. For leases with a term of one year or less Teradyne has elected not to record the lease asset or liability. The lease payments are recognized in the consolidated statement of earnings on a straight-line basis over the lease term. Teradyne includes lease costs within cost of revenues and operating expenses. See Note I: “Leases.”
Engineering and Development Costs	Engineering and Development Costs Teradyne’s products are highly technical in nature and require a large and continuing engineering and development effort. Software development costs incurred prior to the establishment of technological feasibility are charged to expense. Software development costs incurred subsequent to the establishment of technological feasibility are capitalized until the product is available for release to customers. To date, the period between achieving technological feasibility and general availability of the product has been short and software development costs eligible for capitalization have not been material. Engineering and development costs are expensed as incurred and consist primarily of salaries, contractor fees including non-recurring engineering charges related to product design, allocated facility costs, depreciation, and tooling costs.
Stock Compensation Plans and Employee Stock Purchase Plan	Stock Compensation Plans and Employee Stock Purchase Plan Stock-based compensation expense is based on the grant-date fair value estimated in accordance with the provisions of ASC 718-10, “ Compensation-Stock Compensation Excess tax benefits or tax deficiencies are recognized as a discrete tax benefit or discrete tax expense to the current income tax provision in Teradyne’s consolidated statements of operations, all excess tax benefits related to share-based payments are reported as cash flows from operating activities, and all cash payments made to taxing authorities on the employees’ behalf for withheld shares are presented as financing activities on the statement of cash flows. Teradyne elects to account for forfeitures by applying an estimated forfeiture rate and recognizes compensation costs only for those stock-based compensation awards expected to vest. Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”).
Income Taxes	Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The measurement of deferred tax assets is reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be realized. Teradyne performed the required assessment of positive and negative evidence regarding the realization of the net deferred tax assets in accordance with ASC 740, “Accounting for Income Taxes.”
Advertising Costs	Advertising Costs Teradyne expenses all advertising costs as incurred. Advertising costs were $12.8 million, $16.6 million and $15.4 million in 2020, 2019 and 2018, respectively.
Translation of Non-U.S. Currencies	Translation of Non-U.S. Currencies The functional currency for all non-U.S. subsidiaries is the U.S. dollar, except for Universal Robots, MiR and Lemsys for which the local currency is its functional currency. All foreign currency denominated monetary assets and liabilities are remeasured on a monthly basis into the functional currency using exchange rates in effect at the end of the period. All foreign currency denominated non-monetary assets and liabilities are remeasured into the functional currency using historical exchange rates. Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For Universal Robots, MiR and Lemsys, assets and liabilities are translated into U.S. dollars using exchange rates in effect at the end of the period. Revenues and expense amounts are translated using an average of exchange rates in effect during the period. Translation adjustments are recorded within accumulated other comprehensive income (loss) on the balance sheet. Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For the years ended December 31, 2020, 2019, and 2018, losses (gains) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $2.6 million, $(1.6) million, and $(2.5) million, respectively. These amounts do not reflect the corresponding (gains) losses from foreign exchange contracts. See Note H: “Financial Instruments” regarding foreign exchange contracts.
Net Income (Loss) per Common Share	Net Income (Loss) per Common Share Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Except where the result would be anti-dilutive, diluted net income (loss) per common share is calculated by dividing net income (loss) by the sum of the weighted average number of common shares plus common stock equivalents, if applicable. With respect to its convertible debt issued in 2016, Teradyne has determined that it has the ability and intent to settle the principal of the convertible debt in cash; accordingly, the principal amount is excluded from the determination of diluted earnings per share. As a result, Teradyne is accounting for the conversion spread using the treasury stock method.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) includes net income, unrealized pension and postretirement prior service costs and benefits, unrealized gains and losses on investments in debt marketable securities and foreign currency translation adjustment. Prior to 2018, comprehensive income (loss) included unrealized gains and losses on investments in equity marketable securities.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Revenue and Customer Advances	As of December 31, 2020 and 2019, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2020 2019 (in thousands) Maintenance, service and training $ 77,654 $ 63,815 Customer advances, undelivered elements and other 63,438 56,358 Extended warranty 51,929 30,677 Total deferred revenue and customer advances $ 193,021 $ 150,850
Other Accrued Liabilities	The balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2017 $ 8,200 Acquisition 41 Accruals for warranties issued during the period 13,045 Accruals related to pre-existing warranties 921 Settlements made during the period (14,298 ) Balance at December 31, 2018 7,909 Acquisition 14 Accruals for warranties issued during the period 14,106 Accruals related to pre-existing warranties 4,026 Settlements made during the period (17,059 ) Balance at December 31, 2019 8,996 Accruals for warranties issued during the period 28,490 Accruals related to pre-existing warranties 821 Settlements made during the period (21,674 ) Balance at December 31, 2020 $ 16,633
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: Amount (in thousands) Balance at December 31, 2017 $ 24,438 Deferral of new extended warranty revenue 23,753 Recognition of extended warranty deferred revenue (20,769 ) Balance at December 31, 2018 27,422 Deferral of new extended warranty revenue 23,271 Recognition of extended warranty deferred revenue (20,016 ) Balance at December 31, 2019 30,677 Deferral of new extended warranty revenue 41,694 Recognition of extended warranty deferred revenue (20,442 ) Balance at December 31, 2020 $ 51,929
Schedule of Prepayments and Other Current Assets	Prepayments consist of the following and are included in prepayments and other current assets on the balance sheet: 2020 2019 (in thousands) Contract manufacturer and supplier prepayments $ 212,286 $ 143,392 Prepaid taxes 9,361 8,046 Prepaid maintenance and other services 13,116 8,503 Other prepayments 15,329 16,753 Total prepayments $ 250,092 $ 176,694
Useful Lives of Assets	Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 Building improvements 5 Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 Machinery, equipment and software 3

Acquisitions and Investment i_2

Acquisitions and Investment in Other Company (Tables)	12 Months Ended
	Dec. 31, 2020
Pro Forma Results Under Acquisitions	The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: December 31, 2019 December 31, 2018 (in thousands, except per share amount) Revenues $ 2,303,737 $ 2,111,373 Net income $ 464,602 $ 442,082 Net income per common share: Basic $ 2.73 $ 2.36 Diluted $ 2.59 $ 2.30
Mobile Industrial Robots (MiR)
Final Allocation of Purchase Price	The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 135,976 Intangible assets 80,670 Tangible assets acquired and liabilities assumed: Current assets 6,039 Non-current assets 1,336 Accounts payable and current liabilities (7,336 ) Long-term deferred tax liabilities (18,007 ) Other long-term liabilities (900 ) Total purchase price $ 197,778
Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date	Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in Developed technology $ 58,900 7.0 Trademarks and tradenames 13,240 11.0 Customer relationships 8,500 2.5 Backlog 30 0.2 Total intangible assets $ 80,670 7.2
Autoguide LLC [Member]
Final Allocation of Purchase Price	The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 41,223 Intangible assets 37,660 Tangible assets acquired and liabilities assumed: Other current assets 3,661 Non-current assets 1,227 Accounts payable and current liabilities (1,223 ) Long-term other liabilities (949 ) Total purchase price $ 81,599
Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date	Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 24,590 6.0 Customer relationships 7,360 6.0 Trademarks and tradenames 5,450 7.0 Backlog 260 0.3 Total intangible assets $ 37,660 6.1

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition	The following table provides information about disaggregated revenue by timing of revenue recognition, primary geographical market, and major product lines. Semiconductor Test Industrial Automation Wireless Corporate and Other Total System on-a-chip Memory System Test Universa l Mobile AutoGuide (in thousands) For the Year Ended December 31, 2020 (1) Timing of Revenue Recognition Point in Time $ 1,659,414 $ 363,324 $ 348,454 $ 214,212 $ 44,622 $ 10,911 $ 163,834 $ (604 ) $ 2,804,166 Over Time 217,975 18,884 61,275 7,269 211 2,506 9,182 — 317,302 Total $ 1,877,389 $ 382,208 $ 409,729 $ 221,481 $ 44,833 $ 13,417 $ 173,016 $ (604 ) $ 3,121,469 Geographical Market Asia Pacific $ 1,744,593 $ 364,000 $ 258,521 $ 60,277 $ 6,471 $ — $ 143,969 $ — $ 2,577,831 Americas 77,671 12,999 128,482 64,164 16,769 13,417 22,544 (604 ) 335,441 Europe, Middle East and Africa 55,125 5,209 22,726 97,040 21,593 — 6,503 — 208,196 Total $ 1,877,389 $ 382,208 $ 409,729 $ 221,481 $ 44,833 $ 13,417 $ 173,016 $ (604 ) $ 3,121,469 For the Year Ended December 31, 2019 (1) Timing of Revenue Recognition Point in Time $ 1,070,375 $ 247,221 $ 237,686 $ 244,515 $ 44,329 $ 1,144 $ 148,322 $ (515 ) $ 1,993,077 Over Time 216,065 18,910 49,769 7,843 74 234 8,993 — 301,888 Total $ 1,286,440 $ 266,131 $ 287,455 $ 252,358 $ 44,403 $ 1,378 $ 157,315 $ (515 ) $ 2,294,965 Geographical Market Asia Pacific $ 1,152,881 $ 238,714 $ 132,826 $ 68,027 $ 9,513 $ — $ 126,549 $ — $ 1,728,510 Americas 73,257 23,826 129,840 71,926 14,438 1,378 24,234 (515 ) 338,384 Europe, Middle East and Africa 60,302 3,591 24,789 112,405 20,452 — 6,532 — 228,071 Total $ 1,286,440 $ 266,131 $ 287,455 $ 252,358 $ 44,403 $ 1,378 $ 157,315 $ (515 ) $ 2,294,965 For the Year Ended December 31, 2018 (1) Timing of Revenue Recognition Point in Time $ 1,010,493 $ 259,366 $ 167,418 $ 232,448 $ 24,115 $ — $ 122,536 $ (1,205 ) $ 1,815,171 Over Time 208,456 14,102 48,714 4,889 — — 9,470 — 285,631 Total $ 1,218,949 $ 273,468 $ 216,132 $ 237,337 $ 24,115 $ — $ 132,006 $ (1,205 ) $ 2,100,802 Geographical Market Asia Pacific $ 1,067,879 $ 245,264 $ 90,989 $ 58,492 $ 5,950 $ — $ 107,872 $ — $ 1,576,446 Americas 78,498 17,353 96,763 70,478 7,326 — 19,166 (1,205 ) 288,379 Europe, Middle East and Africa 72,572 10,851 28,380 108,367 10,839 — 4,968 — 235,977 Total $ 1,218,949 $ 273,468 $ 216,132 $ 237,337 $ 24,115 $ — $ 132,006 $ (1,205 ) $ 2,100,802 (1) Includes $10.0 million, $8.4 million and $12.0 million in 2020, 2019 and 2018, respectively, for leases of Teradyne’s systems recognized outside of ASC 606: “Revenue from Contracts with Customers.”

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Composition of Inventories, Net	Inventories, net consisted of the following at December 31, 2020 and 2019: 2020 2019 (in thousands) Raw material $ 114,133 $ 118,595 Work-in-process 25,408 32,695 Finished goods 82,648 45,401 $ 222,189 $ 196,691

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant and Equipment, Net	Property, plant and equipment, net consisted of the following at December 31, 2020 and 2019: 2020 2019 (in thousands) Land $ 17,207 $ 16,561 Buildings 108,221 107,282 Machinery, equipment and software 956,035 834,970 Furniture and fixtures 28,487 29,157 Leasehold improvements 61,276 59,378 Construction in progress 13,098 2,537 1,184,324 1,049,885 Less: accumulated depreciation 789,524 729,669 $ 394,800 $ 320,216

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2020 and 2019: December 31, 2020 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 $ 443,166 $ — $ — $ 443,166 Cash equivalents 347,768 123,187 — 470,955 Available for sale securities: U.S. Treasury securities — 258,304 — 258,304 Commercial paper — 254,413 — 254,413 Corporate debt securities — 83,615 — 83,615 Debt mutual funds 8,565 — — 8,565 U.S. government agency securities — 4,339 — 4,339 Certificates of deposit and time deposits — 979 — 979 Non-U.S. government securities — 625 — 625 Equity securities: Mutual funds 29,420 — — 29,420 Total $ 828,919 $ 725,462 $ — $ 1,554,381 Derivative assets — 95 — 95 Total $ 828,919 $ 725,557 $ — $ 1,554,476 Liabilities Contingent consideration $ — $ — $ 7,227 $ 7,227 Derivative liabilities — 504 — 504 Total $ — $ 504 $ 7,227 $ 7,731 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 790,934 $ 123,187 $ — $ 914,121 Marketable securities — 522,280 — 522,280 Long-term marketable securities 37,985 79,995 — 117,980 Prepayments and other current assets — 95 — 95 Total $ 828,919 $ 725,557 $ — $ 1,554,476 Liabilities Other current liabilities $ — $ 504 $ — $ 504 Long-term contingent consideration — — 7,227 7,227 Total $ — $ 504 $ 7,227 $ 7,731 December 31, 2019 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 $ 311,975 $ — $ — $ 311,975 Cash equivalents 410,285 51,664 — 461,949 Available for sale securities: Corporate debt securities — 97,307 — 97,307 Commercial paper — 54,149 — 54,149 U.S. Treasury securities — 42,382 — 42,382 U.S. government agency securities — 9,952 — 9,952 Debt mutual funds 6,888 — — 6,888 Certificates of deposit and time deposits — 4,751 — 4,751 Non-U.S. government securities — 592 — 592 Equity securities: Mutual funds 25,772 — — 25,772 Total $ 754,920 $ 260,797 $ — $ 1,015,717 Derivative assets — 528 — 528 Total $ 754,920 $ 261,325 $ — $ 1,016,245 Liabilities Contingent consideration $ — $ — $ 39,705 $ 39,705 Derivative liabilities — 203 — 203 Total $ — $ 203 $ 39,705 $ 39,908 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 722,260 $ 51,664 $ — $ 773,924 Marketable securities — 137,303 — 137,303 Long-term marketable securities 32,660 71,830 — 104,490 Prepayments and other current assets — 528 — 528 Total $ 754,920 $ 261,325 $ — $ 1,016,245 Liabilities Other current liabilities $ — $ 203 $ — $ 203 Contingent consideration — — 9,106 9,106 Long-term contingent consideration — — 30,599 30,599 Total $ — $ 203 $ 39,705 $ 39,908
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	Changes in the fair value of Level 3 contingent consideration for the years ended December 31, 2020 and 2019 were as follows: Contingent Consideration (in thousands) Balance at December 31, 2018 $ 70,543 Acquisition of AutoGuide 23,976 Foreign currency impact (967 ) Payments (1) (34,590 ) Fair value adjustment (2) (19,257 ) Balance at December 31, 2019 39,705 Foreign currency impact (355 ) Payments (3) (8,852 ) Fair value adjustment (4) (23,271 ) Balance at December 31, 2020 $ 7,227 (1) During the year ended December 31, 2019, Teradyne paid $30.8 million and $3.8 million of contingent consideration for the earn-outs in connection with the acquisitions of MiR and Universal Robots A/S (“Universal Robots”), respectively. (2) During the year ended December 31, 2019, the fair value of contingent consideration for the earn-out in connection with the acquisition of MiR was decreased by $22.2 million primarily due to a decrease in forecasted revenues partially offset by the impact from modification of the earn-out structure. During the year ended December 31, 2019, the fair value of contingent consideration for the earn-out in connection with the acquisition of AutoGuide was increased by $3.0 million primarily due to an increase in forecasted revenues (3) During the year ended December 31, 2020, Teradyne paid $8.9 million of contingent consideration for the earn-out in connection with the acquisition of MiR. (4) During the year ended December 31, 2020, the fair value of contingent consideration for the earn-out in connection with the acquisition of AutoGuide was decreased by $19.7 million primarily due to a decrease in forecasted revenues and earnings before interest and taxes
Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument	The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instrument: Liability December 31, 2020 Fair Value Valuation Technique Unobservable Inputs Weighted Average (in thousands) Contingent consideration (AutoGuide) $ 7,227 Monte Carlo simulation Revenue Volatility 16.5% Discount Rate 1.0%
Schedule of Carrying Amounts and Fair Values of Financial Instruments	The carrying amounts and fair values of Teradyne’s financial instruments at December 31, 2020 and 2019 were as follows: December 31, 2020 December 31, 2019 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 914,121 $ 914,121 $ 773,924 $ 773,924 Marketable securities 640,260 640,260 241,793 241,793 Derivative assets 95 95 528 528 Liabilities Contingent consideration 7,227 7,227 39,705 39,705 Derivative liabilities 504 504 203 203 Convertible debt (1) 410,111 1,739,553 394,687 1,010,275 (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 tables summarize the composition of available-for-sale marketable securities at December 31, 2020 and 2019: December 31, 2020 Available-for-Sale Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) U.S. Treasury securities $ 257,132 $ 1,330 $ (158 ) $ 258,304 $ 17,243 Commercial paper 254,404 10 (1 ) 254,413 12,173 Corporate debt securities 76,129 7,539 (53 ) 83,615 39,896 Debt mutual funds 8,413 152 — 8,565 — U.S. government agency securities 4,294 46 (1 ) 4,339 1,106 Certificates of deposit and time deposits 979 — — 979 — Non-U.S. government securities 625 — — 625 — $ 601,976 $ 9,077 $ (213 ) $ 610,840 $ 70,418 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 522,228 $ 92 $ (40 ) $ 522,280 $ 61,806 Long-term marketable securities 79,748 8,985 (173 ) 88,560 8,612 $ 601,976 $ 9,077 $ (213 ) $ 610,840 $ 70,418 December 31, 2019 Available-for-Sale Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Corporate debt securities $ 93,267 $ 4,081 $ (41 ) $ 97,307 $ 2,009 Commercial paper 54,124 26 (1 ) 54,149 1,391 U.S. Treasury securities 42,167 431 (216 ) 42,382 17,556 U.S. government agency securities 9,942 14 (4 ) 9,952 3,043 Debt mutual funds 6,753 135 — 6,888 — Certificates of deposit and time deposits 4,751 — — 4,751 — Non-U.S. government securities 592 — — 592 — $ 211,596 $ 4,687 $ (262 ) $ 216,021 $ 23,999 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 137,144 $ 160 $ (1 ) $ 137,303 $ 2,922 Long-term marketable securities 74,452 4,527 (261 ) 78,718 21,077 $ 211,596 $ 4,687 $ (262 ) $ 216,021 $ 23,999
Contractual Maturities of Investments Held	The contractual maturities of investments in available-for-sale marketable securities held at December 31, 2020 were as follows: Cost Fair Value (in Due within one year $ 522,228 $ 522,280 Due after 1 year through 5 years 24,829 25,245 Due after 5 years through 10 years 13,030 14,183 Due after 10 years 33,476 40,567 Total $ 593,563 $ 602,275
Schedule of Notional Amount of Derivatives	At December 31, 2020 and 2019, Teradyne had the following contracts to buy and sell non-U.S. currencies for U.S. dollars and other non-U.S. currencies with the following notional amounts: December 31, 2020 December 31, 2019 Buy Position Sell Position Net Total Buy Position Sell Position Net Total (in millions) Japanese Yen $ (14.1 ) $ — $ (14.1 ) $ (29.3 ) $ — $ (29.3 ) Taiwan Dollar (27.9 ) — (27.9 ) (18.4 ) — (18.4 ) Korean Won (5.3 ) — (5.3 ) (10.7 ) — (10.7 ) British Pound Sterling (1.0 ) — (1.0 ) (3.8 ) — (3.8 ) Singapore Dollar — 52.3 52.3 — 25.3 25.3 Euro — 43.9 43.9 — 47.8 47.8 Philippine Peso — 5.0 5.0 — 5.2 5.2 Chinese Yuan — 3.4 3.4 — 4.4 4.4 Total $ (48.3 ) $ 104.6 $ 56.3 $ (62.2 ) $ 82.7 $ 20.5
Schedule of Derivative Instruments in Statement of Financial Position at Fair Value	The following table summarizes the fair value of derivative instruments as of December 31, 2020 and 2019: Balance Sheet Location December 31, 2020 December 31, 2019 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 95 $ 528 Foreign exchange contracts Other current liabilities (504 ) (203 ) Total derivatives $ (409 ) $ 325
Schedule of Effect of Derivative Instruments on Statement of Operations Recognized	The following table summarizes the effect of derivative instruments in the statements of operations recognized for the years ended December 31, 2020, 2019, and 2018. Location of (Gains) Losses Recognized in Statement of Operations December 31, 2020 December 31, 2019 December 31, 2018 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ 3,515 $ 5,960 $ 7,386 (1) The table does not reflect the corresponding gains and losses from the remeasurement of the monetary assets and liabilities denominated in foreign currencies. (2) For the years ended December 31, 2020, net losses from remeasurement of monetary assets and liabilities denominated in foreign currencies were $2.6 million. (3) For the year ended December 31, 2019 and 2018, net gains from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $1.6 million and $2.5 million, respectively.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental cash flow information related to leases	Supplemental cash flows information related to leases was as follows: For the Year Ended Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows: $ 24,136 Right-of-use assets obtained in exchange for new lease obligations 14,801
Schedule of operating lease, maturity	Maturities of lease liabilities as of December 31, 2020 were as follows: Operating Lease (in thousands) 2021 $ 22,451 2022 16,798 2023 9,727 2024 7,215 2025 5,715 Thereafter 6,149 Total lease payments 68,055 Less imputed interest (5,409 ) Total lease liabilities $ 62,646

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Components of Convertible Senior Notes	The below tables represent the key components of Teradyne’s convertible senior notes: December 31, December 31, (in thousands) Debt principal $ 459,971 $ 460,000 Unamortized discount 49,860 65,313 Net carrying amount of convertible debt $ 410,111 $ 394,687 Reported as follows: December 31, December 31, (in thousands) Current debt $ 33,343 $ — Long-term debt 376,768 394,687 Net carrying amount of convertible debt $ 410,111 $ 394,687 For the year ended December 31, December 31, (in thousands) Contractual interest expense on the coupon $ 5,750 $ 5,750 Amortization of the discount component and debt issue fees recognized as interest expense 15,454 14,706 Total interest expense on the convertible debt $ 21,204 $ 20,456

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive (Loss) Income (Tables)	12 Months Ended
	Dec. 31, 2020
Changes in Accumulated Other Comprehensive (Loss) Income	Changes in accumulated other comprehensive (loss) income, which is presented net of tax, consist of the following: Foreign Currency Translation Adjustment Unrealized (Losses) Gains on Marketable Securities Retirement Plans Service Credit Total (in thousands) Balance at December 31, 2018, net of tax of $0, $(521), $(1,081) $ (12,523 ) $ (1,845 ) $ 1,328 $ (13,040 ) Other comprehensive (loss) income before (10,991 ) 6,015 — (4,976 ) Amounts reclassified from accumulated other — (690 ) (148 ) (838 ) Net current period other comprehensive (loss) income, (10,991 ) 5,325 (148 ) (5,814 ) Balance at December 31, 2019, net of tax of $0, $946, $(1,124) $ (23,514 ) $ 3,480 $ 1,180 $ (18,854 ) Other comprehensive income before 48,903 5,839 — 54,742 Amounts reclassified from accumulated other — (2,365 ) (7 ) (2,372 ) Net current period other comprehensive income (loss), 48,903 3,474 (7 ) 52,370 Balance at December 31, 2020, net of tax of $0, $1,910, $(1,126) $ 25,389 $ 6,954 $ 1,173 $ 33,516
Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations	Reclassifications out of accumulated other comprehensive income to the statements of operations for the years ended December 31, 2020, 2019, and 2018, were as follows: Details about Accumulated Other Comprehensive Income Components For the year ended Affected Line Item in the Statements of Operations December 31, 2020 December 31, 2019 December 31, 2018 (in thousands) Available-for-sale marketable securities Unrealized gains (losses), net of tax of $665, $192, $21 $ 2,365 $ 690 $ (1,337 ) Interest income Defined benefit pension and postretirement plans: Amortization of prior service benefit, net of tax of $2, $43, $71 7 148 245 (a) Total reclassifications, net of tax of $667, $235, $92 $ 2,372 $ 838 $ (1,092 ) 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 Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Changes in Carrying Amount of Goodwill by Segment	The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2020 and 2019 are as follows: Industrial Automation Wireless Test Semiconductor Test System Test Total (in thousands) Balance at December 31, 2018: Goodwill $ 363,358 $ 361,819 $ 260,540 $ 158,699 $ 1,144,416 Accumulated impairment losses — (353,843 ) (260,540 ) (148,183 ) (762,566 ) 363,358 7,976 — 10,516 381,850 Lemsys acquisition — — 1,428 — 1,428 AutoGuide acquisition 41,372 — — — 41,372 Foreign currency translation adjustment (8,247 ) — 28 — (8,219 ) Balance at December 31, 2019: Goodwill 396,483 361,819 261,996 158,699 1,178,997 Accumulated impairment losses — (353,843 ) (260,540 ) (148,183 ) (762,566 ) 396,483 7,976 1,456 10,516 416,431 AutoGuide acquisition (149 ) — — — (149 ) Foreign currency translation adjustment 37,418 — 159 — 37,577 Balance at December 31, 2020: Goodwill 433,752 361,819 262,155 158,699 1,216,425 Accumulated impairment losses — (353,843 ) (260,540 ) (148,183 ) (762,566 ) $ 433,752 $ 7,976 $ 1,615 $ 10,516 $ 453,859 Intangible Assets
Schedule of Estimated Intangible Assets Amortization Expense	Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2021 $ 21,893 2022 21,000 2023 20,504 2024 20,192 2025 11,922 Thereafter 5,428
Wireless Test
Schedule of Amortizable Intangible Assets	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets: December 31, 2020 Gross Carrying Amount Accumulated Amortization (1) Foreign Net Carrying Amount (in thousands) Developed technology $ 272,547 $ (210,479 ) $ (1,610 ) $ 60,458 Customer relationships 66,239 (54,524 ) 305 12,020 Tradenames and trademarks 70,120 (42,344 ) 685 28,461 Total intangible assets $ 408,906 $ (307,347 ) $ (620 ) $ 100,939 December 31, 2019 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 361,787 $ (279,000 ) $ (5,709 ) $ 77,078 Customer relationships 75,669 (59,077 ) (455 ) 16,137 Tradenames and trademarks 70,120 (36,671 ) (1,184 ) 32,265 Backlog 260 (260 ) — — Total intangible assets $ 507,836 $ (375,008 ) $ (7,348 ) $ 125,480 (1) In 2020, $98.9 million of amortizable intangible assets became fully amortized and have been eliminated from the gross carrying amount and accumulated amortization.

Net Income Per Common Share (Ta

Net Income Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
Computation of Basic and Diluted Net Income (Loss) Per Common Share	The following table sets forth the computation of basic and diluted net income per common share: 2020 2019 2018 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 784,147 $ 467,468 $ 451,779 Weighted average common shares-basic 166,120 170,425 187,672 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) 8,528 4,909 2,749 Convertible note hedge warrant shares (2) 6,989 2,698 485 Restricted stock units 1,264 1,236 1,385 Stock options 131 178 278 Employee stock purchase rights 10 13 36 Dilutive potential common shares 16,922 9,034 4,933 Weighted average common shares-diluted 183,042 179,459 192,605 Net income per common share-basic $ 4.72 $ 2.74 $ 2.41 Net income per common share-diluted $ 4.28 $ 2.60 $ 2.35 (1) Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.56, multiplied by 14.6 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 $39.60, multiplied by 14.6 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)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligations	The December 31 balances of these defined benefit pension plans assets and obligations are shown below: 2020 2019 United States Foreign United States Foreign (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 203,791 $ 43,952 $ 178,237 $ 39,146 Service cost 1,773 907 1,608 751 Interest cost 5,770 516 7,189 691 Actuarial loss 24,671 2,951 24,447 4,520 Benefits paid (9,844 ) (1,299 ) (7,690 ) (836 ) Retiree annuity purchase (24,379 ) — — — Liability loss due to settlement 451 — — — Non-U.S. currency movement — 3,961 — (320 ) End of year 202,233 50,988 203,791 43,952 Change in plan assets: Fair value of plan assets: Beginning of year 166,932 1,586 144,301 1,400 Actual return on plan assets 23,048 67 27,516 64 Company contributions 3,098 1,079 2,805 923 Benefits paid (9,844 ) (988 ) (7,690 ) (836 ) Retiree annuity purchase (24,379 ) — — — Non-U.S. currency movement — 112 — 35 End of year 158,855 1,856 166,932 1,586 Funded status $ (43,378 ) $ (49,132 ) $ (36,859 ) $ (42,366 )
Amounts Recorded within Statement of Financial Position	The following table provides amounts recorded within the account line items of the statements of financial position as of December 31: 2020 2019 United States Foreign United States Foreign (in thousands) Retirement plans assets $ 17,468 $ — $ 18,457 $ — Accrued employees’ compensation and withholdings (3,273 ) (1,019 ) (2,826 ) (922 ) Retirement plans liabilities (57,573 ) (48,113 ) (52,490 ) (41,444 ) Funded status $ (43,378 ) $ (49,132 ) $ (36,859 ) $ (42,366 )
Amounts Recognized in Accumulated Other Comprehensive Income	The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2020 2019 United States Foreign United States Foreign (in thousands) Deferred taxes related to prior service cost recognized in other comprehensive income $ 560 $ — $ 560 $ —
Pension Plans with Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets	Information for pension plans with an accumulated benefit obligation in excess of plan assets as of Decemb e 2020 2019 United States Foreign United States Foreign (in millions) Projected benefit obligation $ 60.8 $ 51.0 $ 55.3 $ 44.0 Accumulated benefit obligation 58.5 46.5 53.2 39.9 Fair value of plan assets — 1.9 — 1.6
Net Periodic Pension and Postretirement Benefit Costs	For the years ended December 31, 2020, 2019, and 2018, Teradyne’s net periodic pension cost (income) was comprised of the following: 2020 2019 2018 United States Foreign United States Foreign United States Foreign (in thousands) Components of Net Periodic Pension Cost (Income): Service cost $ 1,773 $ 907 $ 1,608 $ 751 $ 2,196 $ 786 Interest cost 5,770 516 7,189 691 8,940 687 Expected return on plan assets (4,840 ) (65 ) (6,042 ) (29 ) (9,049 ) (19 ) Amortization of prior service cost — — — — 58 — Net actuarial loss (gain) 6,463 2,949 2,973 4,485 (4,429 ) 743 Settlement loss 451 — — — 345 — Total net periodic pension cost (income) $ 9,617 $ 4,307 $ 5,728 $ 5,898 $ (1,939 ) $ 2,197 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service cost — — — — (58 ) — Total recognized in other comprehensive income — — — — (58 ) — Total recognized in net periodic pension cost (income) and other comprehensive income $ 9,617 $ 4,307 $ 5,728 $ 5,898 $ (1,997 ) $ 2,197
Weighted Average Assumptions to Determine Net Periodic Cost and Benefit Obligation	Weighted Average Assumptions to Determine Net Periodic Pension Cost at January 1: 2020 2019 2018 United States Foreign United States Foreign United States Foreign Discount rate 2.8 % 1.1 % 4.1 % 1.8 % 3.4 % 1.8 % Expected return on plan assets 3.0 3.8 4.3 2.0 4.3 1.5 Salary progression rate 2.6 2.5 2.3 2.5 2.3 2.7 Weighted Average Assumptions to Determine Pension Obligations at December 31: 2020 2019 United States Foreign United States Foreign Discount rate 2.2 % 0.7 % 3.0 % 1.1 % Salary progression rate 2.4 2.3 2.6 2.5
Weighted Average Pension Asset Allocations by Category	The following table provides weighted average pension asset allocation by asset category at December 31, 2020 and 2019: 2020 2019 United States Foreign United States Foreign Fixed income securities 94.0 % — % 94.0 % — % Equity securities 5.0 — 5.0 — Other 1.0 100.0 1.0 100.0 100.0 % 100.0 % 100.0 % 100.0 %
Target Asset Allocation and Index for Each Asset Category	The target asset allocation and the index for each asset category for the U.S. Plan, per the investment policy, are as follows: Asset Category: Policy Index: Target Allocation U.S. corporate fixed income Bloomberg Barclays U.S. Corporate A or Better Index 75 % Global equity MSCI World Minimum Volatility Index 5 U.S. government fixed income Bloomberg Barclays U.S. Long Government Bond Index 14 High yield fixed income Bloomberg Barclays U.S. Corporate High Yield 2% Issuer Cap Index 5 Cash Citigroup Three Month U.S. Treasury Bill Index 1
Changes in Fair Value of Pension Assets	The fair value of pension plan assets by asset category and by level at December 31, 2020 and December 31, 2019 were as follows: December 31, 2020 United States Foreign Level 1 Level 2 Level Total Level Level 2 Level Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 127,098 $ — $ 127,098 $ — $ — $ — $ — U.S. government securities — 22,250 — 22,250 — — — — Global equity — 7,925 — 7,925 — — — — Other — — — — — 1,856 — 1,856 Cash and cash equivalents 1,582 — — 1,582 — — — — Total $ 1,582 $ 157,273 $ — $ 158,855 $ — $ 1,856 $ — $ 1,856 December 31, 2019 United States Foreign Level 1 Level 2 Level Total Level Level 2 Level Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 133,792 $ — $ 133,792 $ — $ — $ — $ — U.S. government securities — 23,186 — 23,186 — — — — Global equity — 8,344 — 8,344 — — — — Other — — — — — 1,586 — 1,586 Cash and cash equivalents 1,610 — — 1,610 — — — — Total $ 1,610 $ 165,322 $ — $ 166,932 $ — $ 1,586 $ — $ 1,586
Expected Future Benefit Payments	Future benefit payments are expected to be paid as follows: United States Foreign (in thousands) 2021 $ 8,902 $ 1,058 2022 8,782 1,063 2023 9,189 1,313 2024 9,815 1,192 2025 10,374 1,140 2026-2030 54,145 7,053
Postretirement Benefit Plans
Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligations	The December 31 balances of the postretirement assets and obligations are shown below: 2020 2019 (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 9,003 $ 9,256 Service cost 57 41 Interest cost 240 347 Actuarial loss 421 717 Benefits paid (1,205 ) (1,358 ) End of year 8,515 9,003 Change in plan assets: Fair value of plan assets: Beginning of year — — Company contributions 1,205 1,358 Benefits paid (1,205 ) (1,358 ) End of year — — Funded status $ (8,515 ) $ (9,003 )
Amounts Recorded within Statement of Financial Position	The following table provides amounts recorded within the account line items of financial position as of December 31: 2020 2019 (in thousands) Accrued employees’ compensation and withholdings $ (1,161 ) $ (1,231 ) Retirement plans liability (7,354 ) (7,772 ) Funded status $ (8,515 ) $ (9,003 )
Amounts Recognized in Accumulated Other Comprehensive Income	The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2020 2019 (in thousands) Prior service credit, before tax $ (49 ) $ (58 ) Deferred taxes (1,686 ) (1,684 ) Total recognized in other comprehensive income, net of tax $ (1,735 ) $ (1,742 )
Net Periodic Pension and Postretirement Benefit Costs	For the years ended December 31, 2020, 2019, and 2018, Teradyne’s net periodic postretirement benefit cost (income) was comprised of the following: 2020 2019 2018 (in thousands) Components of Net Periodic Postretirement Benefit Cost (income): Service cost $ 57 $ 41 $ 39 Interest cost 240 347 196 Amortization of prior service credit (9 ) (191 ) (373 ) Net actuarial loss 421 717 25 Special termination benefits — — 3,708 Total net periodic postretirement benefit cost 709 914 3,595 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service credit 9 191 373 Total recognized in other comprehensive income 9 191 373 Total recognized in net periodic postretirement cost and other comprehensive income $ 718 $ 1,105 $ 3,968
Weighted Average Assumptions to Determine Net Periodic Cost and Benefit Obligation	Weighted Average Assumptions to Determine Net Periodic Postretirement Benefit Income as of January 1: 2020 2019 2018 Discount rate 3.0 % 4.0 % 3.4 % Initial health care cost trend rate 7.1 7.5 7.9 Ultimate health care cost trend rate 4.5 4.5 4.5 Year in which ultimate health care cost trend rate is reached 2026 2026 2026 2020 2019 2018 Discount rate 2.2 % 3.0 % 4.0 % Initial medical trend 7.3 7.1 7.5 Ultimate health care trend 4.5 4.5 4.5 Medical cost trend rate decrease to ultimate rate in year 2029 2026 2026
Expected Future Benefit Payments	Future benefit payments are expected to be paid as follows: Benefit Payments (in thousands) 2021 $ 1,161 2022 961 2023 786 2024 646 2025 533 2026-2030 1,601

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
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: 2020 2019 2018 Risk-free interest rate 1.5 % 2.6 % 2.2 % Teradyne volatility-historical 34.9 % 31.9 % 26.8 % NYSE Composite Index volatility-historical 11.4 % 11.9 % 12.4 % Dividend yield 0.6 % 1.0 % 0.8 %
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: 2020 2019 2018 Expected life (years) 5.0 5.0 5.0 Risk-free interest rate 1.5 % 2.5 % 2.4 % Volatility-historical 32.0 % 30.1 % 26.4 % Dividend yield 0.5 % 1.0 % 0.8 %
Stock Compensation Plan Activity	Stock compensation plan activity for the years 2020, 2019, and 2018, is as follows: 2020 2019 2018 (in thousands) Restricted Stock Units: Non-vested at January 1 2,269 2,454 3,174 Awarded 616 1,139 790 Vested (1,028 ) (1,237 ) (1,382 ) Forfeited (68 ) (87 ) (128 ) Non-vested at December 31 1,789 2,269 2,454 Stock Options: Outstanding at January 1 319 506 531 Granted 56 102 69 Exercised (159 ) (280 ) (94 ) Forfeited — (7 ) — Expired — (2 ) — Outstanding at December 31 216 319 506 Vested and expected to vest at December 31 216 319 506 Exercisable at December 31 27 85 256
Share Based Compensation Total Shares Available	Total shares available for the years 2020, 2019, and 2018: 2020 2019 2018 (in thousands) Shares available: Available for grant at January 1 6,727 7,874 8,605 Options granted (56 ) (102 ) (69 ) Options forfeited — 7 Restricted stock units awarded (616 ) (1,139 ) (790 ) Restricted stock units forfeited 68 87 128 Available for grant at December 31 6,123 6,727 7,874
Weighted-Average Restricted Stock Unit Award Date Fair Value	Weighted average restricted stock unit award date fair value information for the years 2020, 2019, and 2018, is as follows: 2020 2019 2018 Non-vested at January 1 $ 35.58 $ 29.22 $ 21.71 Awarded 72.76 39.08 45.99 Vested 31.53 23.59 20.20 Forfeited 45.36 35.60 24.67 Non-vested at December 31 $ 47.84 $ 35.58 $ 29.22
Restricted Stock Unit Awards Aggregate Intrinsic Value	Restricted stock unit awards aggregate intrinsic value information at December 31 for the years 2020, 2019, and 2018 is as follows: 2020 2019 2018 (in thousands) Vested $ 71,582 $ 46,110 $ 63,688 Outstanding 214,509 154,752 77,015 Expected to vest 210,301 152,374 77,187
Restricted Stock Units Weighted Average Remaining Contractual Terms	Restricted stock units weighted average remaining contractual terms (in years) information at December 31 for the years 2020, 2019, and 2018 is as follows: 2020 2019 2018 Outstanding 0.96 1.02 0.92 Expected to vest 0.96 1.02 0.91
Weighted Average Stock Options Exercise Price	Weighted average stock options exercise price information for the year ended December 31, 2020 is as follows: 2020 Outstanding at January 1 $ 29.91 Options granted 72.61 Options exercised 23.77 Options forfeited — Options cancelled — Outstanding at December 31 45.59 Exercisable at December 31 23.51
Stock Option Aggregate Intrinsic Value Information	Stock option aggregate intrinsic value information for the years ended December 31, 2020, 2019, and 2018 is as follows: 2020 2019 2018 (in thousands) Exercised $ 9,682 $ 9,232 $ 2,960 Outstanding 16,083 12,218 7,359 Vested and expected to vest 13,499 7,701 7,359 Exercisable 2,584 4,517 5,905
Stock Options Weighted Average Remaining Contractual Terms	Stock options weighted average remaining contractual terms (in years) information at December 31, for the years 2020, 2019, and 2018 is as follows: 2020 2019 2018 Outstanding 4.6 4.2 3.6 Vested and expected to vest 4.9 5.0 3.6 Exercisable 2.5 2.1 2.4
Effect to Income (Loss) from Operations for Recording Stock-Based Compensation	The following table provides the effect to income from operations for recording stock-based compensation for the years ended December 31, 2020, 2019, and 2018: 2020 2019 2018 (in thousands) Cost of revenues $ 4,227 $ 3,480 $ 3,129 Engineering and development 12,039 9,913 9,181 Selling and administrative 28,640 24,504 21,267 Stock-based compensation 44,906 37,897 33,577 Income tax benefit (13,060 ) (8,360 ) (12,036 ) Total stock-based compensation expense after income taxes $ 31,846 $ 29,537 $ 21,541

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Schedule of Income (Loss) Before Income Taxes and Provision (Benefit) for Income Taxes from Operations	The components of income (loss) before income taxes and the provision (benefit) for income taxes as shown in the consolidated statements of operations were as follows: 2020 2019 2018 (in thousands) Income before income taxes: U.S. $ 312,153 $ 192,442 $ 189,691 Non-U.S. 588,862 333,330 278,110 $ 901,015 $ 525,772 $ 467,801 Provision (benefit) for income taxes: Current: U.S. Federal $ 58,678 $ 19,297 $ (59,122 ) Non-U.S. 75,193 52,810 45,083 State (1,315 ) (4,347 ) 1,721 132,556 67,760 (12,318 ) Deferred: U.S. Federal (12,604 ) (4,522 ) 29,252 Non-U.S. (5,127 ) (8,007 ) (1,243 ) State 2,043 3,073 331 (15,688 ) (9,456 ) 28,340 Total provision for income taxes: $ 116,868 $ 58,304 $ 16,022
Reconciliation of Effective Tax Rate	A reconciliation of the effective tax rate for the years 2020, 2019 and 2018 is as follows: 2020 2019 2018 U.S. statutory federal tax rate 21.0 % 21.0 % 21.0 % U.S. global intangible low-taxed income 5.7 6.2 0.3 State income taxes, net of federal tax benefit 0.3 0.5 0.1 Foreign taxes (5.6 ) (4.0 ) (2.0 ) Foreign tax credits (4.8 ) (5.9 ) (2.2 ) U.S. foreign derived intangible income (2.2 ) (2.6 ) (1.8 ) U.S. research and development credit (1.3 ) (1.8 ) (2.2 ) Equity compensation (0.6 ) (0.7 ) (1.2 ) Uncertain tax positions (0.1 ) (4.3 ) 1.0 U.S. transition tax — 1.9 (10.5 ) Impact of rate change on deferred taxes — — 0.3 Other, net 0.6 0.8 0.6 13.0 % 11.1 % 3.4 %
Deferred Tax Assets (Liabilities)	Significant components of Teradyne’s deferred tax assets (liabilities) as of December 31, 2020 and 2019 were as follows: 2020 2019 (in thousands) Deferred tax assets: Tax credits $ 87,595 $ 79,480 Accruals 33,156 25,424 Pension liabilities 28,348 24,459 Inventory valuations 18,427 18,572 Lease liability 12,627 13,093 Deferred revenue 9,235 7,622 Equity compensation 6,543 7,042 Vacation accrual 5,890 4,768 Investment impairment 3,292 3,292 Net operating loss carryforwards 1,823 2,705 Other 626 187 Gross deferred tax assets 207,562 186,644 Less: valuation allowance (84,962 ) (77,177 ) Total deferred tax assets $ 122,600 $ 109,467 Deferred tax liabilities: Depreciation $ (14,525 ) $ (18,238 ) Intangible assets (12,726 ) (16,705 ) Right of use assets (10,688 ) (11,197 ) Contingent consideration (3,515 ) — Marketable securities (3,344 ) (1,601 ) Other (710 ) (611 ) Total deferred tax liabilities $ (45,508 ) $ (48,352 ) Net deferred assets $ 77,092 $ 61,115
Operating Loss Carryforwards	At December 31, 2020, Teradyne had operating loss carryforwards that expire in the following years: State Operating Loss Carryforwards Foreign Operating Loss Carryforwards (in thousands) 2021 $ 333 $ — 2022 2,203 — 2023 3,368 — 2024 812 — 2025 191 — 2026-2030 7,452 — 2031-2035 2,147 68 Beyond 2035 73 — Non-expiring 870 3,923 Total $ 17,449 $ 3,991
Unrecognized Tax Benefits	Teradyne’s gross unrecognized tax benefits for the years ended December 31, 2020, 2019 and 2018 were as follows: 2020 2019 2018 (in thousands) Beginning balance as of January 1 $ 21,180 $ 43,395 $ 36,263 Additions: Tax positions for current year 1,082 1,322 4,716 Tax positions for prior years 66 8,043 2,626 Reductions: Tax positions for prior years (2,989 ) (31,397 ) (153 ) Expiration of statutes (1,436 ) (183 ) (57 ) Ending balance as of December 31 $ 17,903 $ 21,180 $ 43,395

Operating Segment, Geographic_2

Operating Segment, Geographic and Significant Customer Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Information	Segment information for the years ended December 31, 2020, 2019, and 2018 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate and Other Consolidated (in thousands) 2020 Revenues $ 2,259,597 $ 409,729 $ 279,731 $ 173,016 $ (604 ) $ 3,121,469 Income (loss) before taxes (1)(2) 739,695 152,092 (24,019 ) 41,950 (8,703 ) 901,015 Total assets (3) 1,070,378 138,295 712,936 106,273 1,624,464 3,652,346 Property additions 168,055 3,092 8,899 4,931 — 184,977 Depreciation and amortization expense 64,998 3,426 36,242 6,258 15,819 126,743 2019 Revenues $ 1,552,571 $ 287,455 $ 298,139 $ 157,315 $ (515 ) $ 2,294,965 Income (loss) before taxes (1)(2) 416,973 93,543 (5,916 ) 35,585 (14,413 ) 525,772 Total assets (3) 784,808 131,428 671,559 97,299 1,101,920 2,787,014 Property additions 112,145 3,059 9,076 10,362 — 134,642 Depreciation and amortization expense 59,197 5,518 40,904 5,365 9,671 120,655 2018 Revenues $ 1,492,417 $ 216,132 $ 261,452 $ 132,006 $ (1,205 ) $ 2,100,802 Income (loss) before taxes (1)(2) 397,645 48,857 7,670 29,052 (15,423 ) 467,801 Total assets (3) 669,452 88,098 607,502 77,570 1,263,984 2,706,606 Property additions 94,496 3,469 11,188 5,226 — 114,379 Depreciation and amortization expense 58,095 6,430 36,755 5,328 6,616 113,224 (1) Included in Corporate and Other are: contingent consideration adjustments, investment impairment, pension and postretirement plans actuarial gains (losses), severance charges, interest income, interest expense, net foreign exchange gains (losses), intercompany eliminations and acquisition related charges. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, and inventory charges. (3) Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.
Schedule of Segment Reporting Information by Segment Charges	Included in each segment are charges and credits in the following line items in the statements of operations: For the Year Ended December 31, 2020 2019 2018 (in thousands) Semiconductor Test: Cost of revenues—inventory charge $ 11,013 $ 8,731 $ 6,822 Contract termination settlement fee 4,000 — — Restructuring and other—employee severance — 1,277 8,429 System Test: Cost of revenues—inventory charge $ 887 $ 2,000 $ 1,175 Industrial Automation: Restructuring and other—acquisition related expenses and compensation $ 985 $ 741 $ 1,163 Cost of revenues—inventory charge 834 508 680 Restructuring and other—employee severance 1,584 796 — Wireless: Cost of revenues—inventory charge $ 4,800 $ 4,005 $ 2,565 Corporate and Other: Restructuring and other—AutoGuide contingent consideration adjustment $ (19,724 ) $ 2,976 $ — Restructuring and other—MiR contingent consideration adjustment (3,546 ) (22,199 ) 17,666 Restructuring and other—acquisition related expenses and compensation 1,728 1,765 3,422 Other (income) expense, net—investment impairment charge — 15,000 — Selling and administrative—equity modification charge 766 2,108 — Restructuring and other—Universal Robots contingent consideration adjustment — — (16,679 )
Revenues by Country	Information as to Teradyne’s revenues by country is as follows: 2020 2019 2018 (in thousands) Revenues from customers (1): Taiwan $ 1,178,068 $ 485,681 $ 516,322 China 465,722 514,327 348,942 Korea 391,571 239,504 163,224 United States 321,674 333,059 282,869 Europe 205,587 219,015 223,207 Japan 143,983 175,322 158,281 Thailand 138,787 87,503 59,184 Singapore 76,460 84,111 108,618 Philippines 68,887 54,560 77,996 Malaysia 56,096 58,200 122,797 Rest of the World 74,634 43,683 39,362 $ 3,121,469 $ 2,294,965 $ 2,100,802 (1) Revenues attributable to a country are based on location of customer site.
Long-Lived Assets by Geographic Area	Long-lived assets by geographic area: United States Foreign(1) Total (in thousands) December 31, 2020 $ 291,234 $ 158,135 $ 449,369 December 31, 2019 $ 252,812 $ 124,943 $ 377,755 (1) As of December 31, 2020 and 2019, long-lived assets attributable to Singapore were $62.5 million and $35.2 million, respectively.

Supplementary Information (Tabl

Supplementary Information (Tables)	12 Months Ended
	Dec. 31, 2020
Consolidated Quarterly Statements of Operations	The following sets forth certain unaudited consolidated quarterly statements of operations data for each of Teradyne’s last eight quarters. In management’s opinion, this quarterly information reflects all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement for the periods presented. Such quarterly results are not necessarily indicative of future results of operations and should be read in conjunction with the audited consolidated financial statements of Teradyne and the notes thereto included elsewhere herein. 2020 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (2)(5) (3)(5) (4)(5) (in thousands, except per share amounts) Revenues: Products $ 610,906 $ 734,630 $ 697,745 $ 647,625 Services 93,449 104,031 121,739 111,343 Total revenues 704,355 838,661 819,484 758,968 Cost of revenues: Cost of products 259,996 322,732 300,174 274,574 Cost of services 38,809 44,456 60,382 34,605 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 298,805 367,188 360,556 309,179 Gross profit 405,550 471,473 458,928 449,789 Operating expenses: Selling and administrative 111,388 113,259 115,840 124,279 Engineering and development 85,159 94,102 94,909 100,795 Acquired intangible assets amortization 9,891 8,941 6,219 5,752 Restructuring and other (7,606 ) 37,222 (27,701 ) (15,117 ) Total operating expenses 198,832 253,524 189,267 215,709 Income from operations 206,718 217,949 269,661 234,080 Non-operating (income) expense: Interest income (2,751 ) (1,368 ) (1,071 ) (793 ) Interest expense 5,551 6,043 6,237 6,351 Other (income) expense, net 6,849 (4,017 ) 764 5,597 Income before income taxes 197,069 217,291 263,731 222,925 Income tax provision 20,878 28,383 41,013 26,595 Net income $ 176,191 $ 188,908 $ 222,718 $ 196,330 Net income per common share—basic $ 1.06 $ 1.14 $ 1.34 $ 1.18 Net income per common share—diluted $ 0.97 $ 1.05 $ 1.21 $ 1.05 Cash dividend declared per common share $ 0.10 $ 0.10 $ 0.10 $ 0.10 (1) Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test. (2) Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability. (3) Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation. (4) Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation. (5) Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy. 2019 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (2) (3) (4)(5)(6) (in thousands, except per share amounts) Revenues: Products $ 393,442 $ 457,511 $ 488,170 $ 548,552 Services 100,657 106,667 93,868 106,098 Total revenues 494,099 564,178 582,038 654,650 Cost of revenues: Cost of products 165,368 193,299 197,196 226,184 Cost of services 41,096 46,961 39,804 45,228 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 206,464 240,260 237,000 271,412 Gross profit 287,635 323,918 345,038 383,238 Operating expenses: Selling and administrative 102,013 108,811 109,166 117,092 Engineering and development 76,791 81,434 77,804 86,794 Acquired intangible assets amortization 10,634 10,083 9,647 9,784 Restructuring and other 5,112 (10,404 ) (6,500 ) (2,088 ) Total operating expenses 194,550 189,924 190,117 211,582 Income from operations 93,085 133,994 154,921 171,656 Non-operating (income) expense: Interest income (4,989 ) (4,384 ) (4,433 ) (3,185 ) Interest expense 5,520 5,800 5,463 5,441 Other (income) expense, net (1,425 ) 1,401 2,158 20,514 Income before income taxes 93,979 131,177 151,733 148,886 Income tax provision (benefit) (15,159 ) 33,780 15,873 23,811 Net income $ 109,138 $ 97,397 $ 135,860 $ 125,075 Net income per common share—basic $ 0.63 $ 0.57 $ 0.80 $ 0.75 Net income per common share—diluted $ 0.62 $ 0.55 $ 0.75 $ 0.69 Cash dividend declared per common share $ 0.09 $ 0.09 $ 0.09 $ 0.09 (1) Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges. (2) Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation. (3) Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation. (4) Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation. (5) Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy. (6) Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.

The Company - Additional inform

The Company - Additional information (Detail)	Nov. 13, 2019USD ($)	Apr. 25, 2018USD ($)	Feb. 26, 2018USD ($)	Jan. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Feb. 28, 2020USD ($)	Jun. 03, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Contingent consideration	$ 24,000,000	$ 30,800,000			$ 8,900,000	$ 8,900,000
Investment impairment					15,000,000	15,000,000
Industrial Automation
Business Acquisition [Line Items]
Total preliminary purchase price	81,600,000
Real War In [Member]
Business Acquisition [Line Items]
Equity Method Investments					0	0			$ 15,000,000
Repaymentof debt demanded								$ 25,000,000
Mobile Industrial Robots (MiR)
Business Acquisition [Line Items]
Cash paid to acquire outstanding common and preferred stock		145,200,000
Total preliminary purchase price		197,800,000
Contingent consideration		$ 52,600,000			9,100,000	9,100,000				$ 31,000,000
Arrangement range of outcomes value high							$ 0			$ 0
Energid Technologies Corporation [Member]
Business Acquisition [Line Items]
Total preliminary purchase price			$ 27,600,000
Lemsys [Member]
Business Acquisition [Line Items]
Total preliminary purchase price				$ 9,100,000
Autoguide LLC
Business Acquisition [Line Items]
Arrangement range of outcomes value high	100,200,000						$ 100,200,000
Autoguide LLC | Industrial Automation
Business Acquisition [Line Items]
Cash paid to acquire outstanding common and preferred stock	57,600,000
Contingent consideration	$ 24,000,000
Business acquisition percentage of equity	100.00%
Arrangement range of outcomes value high					$ 100,200,000	$ 100,200,000
Quantity of material to be transported	4,500

Accounting Policies - Additiona

Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) in adoption of new accounting guidance amount	$ 387,414	$ (241,918)
Standard warranty period	12 months
Depreciation over life to cost of revenues and selling and administrative expenses, years	6 years
Net book value of internally manufactured test systems sold	$ 7,300	5,000	$ 3,800
Advertising costs	12,800	16,600	15,400
Losses (gains) on foreign currency transactions	(2,600)	1,600	$ 2,500
Trade Accounts Receivable	$ 131,100	$ 143,600
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

Deferred Revenue and Customer A

Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Revenue Arrangement
Maintenance, service and training	$ 77,654	$ 63,815
Customer advances, undelivered elements and other	63,438	56,358
Extended warranty	51,929	30,677	$ 27,422	$ 24,438
Total deferred revenue and customer advances	$ 193,021	$ 150,850

Warranty Accrual Included in Ot

Warranty Accrual Included in Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 8,996	$ 7,909	$ 8,200
Acquisition		14	41
Accruals for warranties issued during the period	28,490	14,106	13,045
Accruals related to pre-existing warranties	821	4,026	921
Settlements made during the period	(21,674)	(17,059)	(14,298)
Balance at end of period	$ 16,633	$ 8,996	$ 7,909

Extended Product Warranty of Sh

Extended Product Warranty of Short and Long-Term Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 30,677	$ 27,422	$ 24,438
Deferral of new extended warranty revenue	41,694	23,271	23,753
Recognition of extended warranty deferred revenue	(20,442)	(20,016)	(20,769)
Balance at end of period	$ 51,929	$ 30,677	$ 27,422

Schedule of Prepayments and Oth

Schedule of Prepayments and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid And Other Current Assets [Line Items]
Contract manufacturer and supplier prepayments	$ 212,286	$ 143,392
Prepaid taxes	9,361	8,046
Prepaid maintenance and other services	13,116	8,503
Other prepayments	15,329	16,753
Total prepayments	$ 250,092	$ 176,694

Useful Lives of Assets (Detail)

Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2020
Buildings
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	40 years
Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years
Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	10 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful lives, description	Lesser of lease term or 10 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	10 years
Test Systems Manufactured Internally
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	6 years
Machinery Equipment And Software | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	3 years
Machinery Equipment And Software | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years

Acquisitions and Investment i_3

Acquisitions and Investment in Other Company - Additional Information (Detail)	Nov. 13, 2019USD ($)	Jan. 30, 2019USD ($)	Apr. 25, 2018USD ($)	Feb. 26, 2018USD ($)	Jan. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Feb. 28, 2020USD ($)	Jun. 03, 2019USD ($)
Business Acquisition [Line Items]
Contingent consideration	$ 24,000,000		$ 30,800,000			$ 8,900,000	$ 8,900,000		$ 8,900,000
Goodwill						416,431,000	416,431,000	$ 453,859,000	416,431,000	$ 381,850,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								7 years 2 months 12 days
Investment impairment							15,000,000		15,000,000
Industrial Automation [Member]
Business Acquisition [Line Items]
Total preliminary purchase price	81,600,000
Goodwill						396,483,000	396,483,000	$ 433,752,000	396,483,000	363,358,000
Estimate of Fair Value Measurement [Member]
Business Acquisition [Line Items]
Contingent consideration						39,705,000	39,705,000	7,227,000	39,705,000
Real War In [Member]
Business Acquisition [Line Items]
Equity Method Investments						0	0		0			$ 15,000,000
Repaymentof debt demanded											$ 25,000,000
Mobile Industrial Robots (MiR)
Business Acquisition [Line Items]
Total preliminary purchase price			197,778,000
Cash paid to acquire outstanding common and preferred stock			145,200,000
Contingent consideration			52,600,000			9,100,000	9,100,000		9,100,000	31,000,000
Arrangement range of outcomes value high								0		0
Goodwill, not deductible for tax purposes			136,000,000
Net income									464,602,000	442,082,000
Total preliminary purchase price			197,800,000
Goodwill			$ 135,976,000
Mobile Industrial Robots (MiR) | Fair Value Adjustment to Inventory
Business Acquisition [Line Items]
Revenues										400,000
Mobile Industrial Robots (MiR) | Acquisition Related Costs
Business Acquisition [Line Items]
Net income										2,900,000
Energid Technologies Corporation
Business Acquisition [Line Items]
Total preliminary purchase price				$ 27,600,000
Goodwill				14,400,000
Acquired value of intangible assets				$ 12,300,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				7 months 21 days
Net tangible assets				$ 1,000,000
Lemsys [Member]
Business Acquisition [Line Items]
Total preliminary purchase price		$ 1,400,000			$ 1,400,000
Total preliminary purchase price					9,100,000
Acquired value of intangible assets		$ 4,600,000			4,600,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		5 years 2 months 12 days
Net tangible assets		$ 3,100,000			$ 3,100,000
Autoguide LLC [Member]
Business Acquisition [Line Items]
Total preliminary purchase price								81,599,000
Arrangement range of outcomes value high	100,200,000							100,200,000
Goodwill, not deductible for tax purposes	41,200,000
Revenues						1,400,000
Income (loss) before income taxes						(900,000)
Goodwill								$ 41,223,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								6 years 1 month 6 days
Autoguide LLC [Member] | Industrial Automation [Member]
Business Acquisition [Line Items]
Total preliminary purchase price	81,600,000
Cash paid to acquire outstanding common and preferred stock	57,600,000
Contingent consideration	$ 24,000,000
Arrangement range of outcomes value high						$ 100,200,000	$ 100,200,000		100,200,000
Quantity of material to be transported	4,500
Business acquisition percentage of equity	100.00%
Autoguide LLC [Member] | Estimate of Fair Value Measurement [Member]
Business Acquisition [Line Items]
Revenues									100,000	100,000
Autoguide LLC [Member] | Acquisition Related Costs
Business Acquisition [Line Items]
Net income									$ 1,200,000	$ 1,200,000

Final Allocation of Purchase Pr

Final Allocation of Purchase Price (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 25, 2018
Business Acquisition [Line Items]
Goodwill	$ 453,859	$ 416,431	$ 381,850
Autoguide LLC [Member]
Business Acquisition [Line Items]
Goodwill	41,223
Intangible assets	37,660
Other current assets	3,661
Non-current assets	1,227
Accounts payable and current liabilities	(1,223)
Other long-term liabilities	(949)
Total purchase price	$ 81,599
Mobile Industrial Robots (MiR)
Business Acquisition [Line Items]
Goodwill				$ 135,976
Intangible assets				80,670
Current assets				6,039
Non-current assets				1,336
Accounts payable and current liabilities				(7,336)
Long-term deferred tax liabilities				(18,007)
Other long-term liabilities				(900)
Total purchase price				$ 197,778

Components of Intangible Assets

Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 80,670
Total intangible assets, estimated useful life, years	7 years 2 months 12 days
Autoguide LLC [Member]
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 37,660
Total intangible assets, estimated useful life, years	6 years 1 month 6 days
Developed technology
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 58,900
Total intangible assets, estimated useful life, years	7 years
Developed technology | Autoguide LLC [Member]
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 24,590
Total intangible assets, estimated useful life, years	6 years
Customer Relationships
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 8,500
Total intangible assets, estimated useful life, years	2 years 6 months
Customer Relationships | Autoguide LLC [Member]
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 7,360
Total intangible assets, estimated useful life, years	6 years
Trademarks and tradenames
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 13,240
Total intangible assets, estimated useful life, years	11 years
Trademarks and tradenames | Autoguide LLC [Member]
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 5,450
Total intangible assets, estimated useful life, years	7 years
Customer backlog
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 30
Total intangible assets, estimated useful life, years	2 months 12 days
Customer backlog | Autoguide LLC [Member]
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 260
Total intangible assets, estimated useful life, years	3 months 18 days

Pro Forma Results Under Acquisi

Pro Forma Results Under Acquisition (Detail) - Mobile Industrial Robots (MiR) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Revenue	$ 2,303,737	$ 2,111,373
Net income	$ 464,602	$ 442,082
Net income per common share, basic	$ 2.73	$ 2.36
Net income per common share, diluted	$ 2.59	$ 2.30

Revenue - Additional Informatio

Revenue - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Revenue And Customer Advances	$ 91	$ 65.6	$ 69.9
Revenue, Remaining Performance Obligation, Amount	$ 929.6
Short-term Contract with Customer [Member]
Revenue, Remaining Performance Obligation, Percentage	92.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	12 months
Long-term Contract with Customer [Member]
Revenue, Remaining Performance Obligation, Percentage	8.00%
Long-term Contract with Customer [Member] | Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	3 years
Long-term Contract with Customer [Member] | Minimum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	1 year

Disaggregated Revenue by Primar

Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total	[1],[2]	$ 3,121,469	$ 2,294,965	$ 2,100,802
Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		2,259,597	1,552,571	1,492,417
System Test
Disaggregation of Revenue [Line Items]
Total	[1]	409,729	287,455	216,132
Industrial Automation
Disaggregation of Revenue [Line Items]
Total		279,731	298,139	261,452
Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	173,016	157,315	132,006
Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(604)	(515)	(1,205)
Point in Time
Disaggregation of Revenue [Line Items]
Total	[1]	2,804,166	1,993,077	1,815,171
Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	348,454	237,686	167,418
Point in Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	163,834	148,322	122,536
Point in Time | Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(604)	(515)	(1,205)
Over Time
Disaggregation of Revenue [Line Items]
Total	[1]	317,302	301,888	285,631
Over Time | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	61,275	49,769	48,714
Over Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	9,182	8,993	9,470
Americas
Disaggregation of Revenue [Line Items]
Total	[1]	335,441	338,384	288,379
Americas | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	128,482	129,840	96,763
Americas | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	22,544	24,234	19,166
Americas | Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(604)	(515)	(1,205)
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Total	[1]	208,196	228,071	235,977
Europe, Middle East and Africa | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	22,726	24,789	28,380
Europe, Middle East and Africa | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	6,503	6,532	4,968
Asia Pacific
Disaggregation of Revenue [Line Items]
Total	[1]	2,577,831	1,728,510	1,576,446
Asia Pacific | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	258,521	132,826	90,989
Asia Pacific | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	143,969	126,549	107,872
SOC | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,877,389	1,286,440	1,218,949
SOC | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,659,414	1,070,375	1,010,493
SOC | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	217,975	216,065	208,456
SOC | Americas | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	77,671	73,257	78,498
SOC | Europe, Middle East and Africa | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	55,125	60,302	72,572
SOC | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,744,593	1,152,881	1,067,879
Memory | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	382,208	266,131	273,468
Memory | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	363,324	247,221	259,366
Memory | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	18,884	18,910	14,102
Memory | Americas | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	12,999	23,826	17,353
Memory | Europe, Middle East and Africa | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	5,209	3,591	10,851
Memory | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	364,000	238,714	245,264
Universal Robots (UR) | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	221,481	252,358	237,337
Universal Robots (UR) | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	214,212	244,515	232,448
Universal Robots (UR) | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	7,269	7,843	4,889
Universal Robots (UR) | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	64,164	71,926	70,478
Universal Robots (UR) | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	97,040	112,405	108,367
Universal Robots (UR) | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	60,277	68,027	58,492
MiR | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	44,833	44,403	24,115
MiR | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	44,622	44,329	24,115
MiR | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	211	74
MiR | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	16,769	14,438	7,326
MiR | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	21,593	20,452	10,839
MiR | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	6,471	9,513	$ 5,950
Autoguide LLC [Member] | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	13,417	1,378
Autoguide LLC [Member] | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	10,911	1,144
Autoguide LLC [Member] | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	2,506	234
Autoguide LLC [Member] | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	$ 13,417	$ 1,378
[1]	Includes $10.0 million, $8.4 million and $12.0 million in 2020, 2019 and 2018, respectively, for leases of Teradyne’s systems recognized outside of ASC 606: “Revenue from Contracts with Customers.”
[2]	Revenues attributable to a country are based on location of customer site.

Disaggregated Revenue by Prim_2

Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Revenue on leases	$ 10	$ 8.4	$ 12

Composition of Inventories, Net

Composition of Inventories, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw material	$ 114,133	$ 118,595
Work-in-process	25,408	32,695
Finished goods	82,648	45,401
Inventories, net	$ 222,189	$ 196,691

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory [Line Items]
Inventory reserves	$ 110.6	$ 103.6

Property Plant and Equipment, N

Property Plant and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Land	$ 17,207	$ 16,561
Buildings	108,221	107,282
Machinery, equipment and software	956,035	834,970
Furniture and fixtures	28,487	29,157
Leasehold improvements	61,276	59,378
Construction in progress	13,098	2,537
Property, Plant and Equipment, Gross, Total	1,184,324	1,049,885
Less: accumulated depreciation	789,524	729,669
Property, plant and equipment, net	$ 394,800	$ 320,216

Property, Plant and Equipment -

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation of property, plant and equipment	$ 80,119	$ 70,834	$ 67,415
Machinery and equipment	956,035	834,970
Accumulated depreciation	789,524	729,669
Test Systems Leased By Customers
Property, Plant and Equipment [Line Items]
Machinery and equipment	23,400	5,400
Accumulated depreciation	$ 7,500	$ 5,100

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 13, 2019
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized gain	$ 4,600,000	$ 1,300,000	$ 4,000,000
Available-for-sale securities, realized loss	300,000	200,000	1,600,000
Aggregate loss of investments with unrealized losses less than one year	70,400,000	23,600,000
Unrealized Gain (loss) on contracts	(2,600,000)	1,600,000	$ 2,500,000
Equity securities unrealized gain	9,600,000	5,300,000
Equity securities unrealized loss	$ 6,000,000	$ 400,000
Accounts Receivable | Customer 1 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage	25.00%
Accounts Receivable | Customer 2 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage		10.00%
Debt Mutual Funds
Financial Instruments and Fair Value [Line Items]
Available for sale securities with out contractual maturity date	$ 8,600,000
Autoguide LLC [Member]
Financial Instruments and Fair Value [Line Items]
Maximum amount of contingent consideration paid for acquisition	100,200,000			$ 100,200,000
Foreign Exchange Contracts
Financial Instruments and Fair Value [Line Items]
Unrealized Gain (loss) on contracts	$ 400,000	$ 300,000

Schedule of Fair Value of Finan

Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Nov. 13, 2019	Apr. 25, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	$ 610,840	$ 216,021
Contingent consideration		8,900	$ 24,000	$ 30,800
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	258,304	42,382
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	254,413	54,149
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,615	97,307
Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	979	4,751
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	4,339	9,952
Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	8,565	6,888
Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	625	592
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,554,381	1,015,717
Derivative assets	95	528
Total	1,554,476	1,016,245
Contingent consideration	7,227	39,705
Derivative liabilities	504	203
Total	7,731	39,908
Fair Value, Measurements, Recurring | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	443,166	311,975
Fair Value, Measurements, Recurring | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	470,955	461,949
Fair Value, Measurements, Recurring | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	258,304	42,382
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	254,413	54,149
Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,615	97,307
Fair Value, Measurements, Recurring | Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	979	4,751
Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	4,339	9,952
Fair Value, Measurements, Recurring | Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	8,565	6,888
Fair Value, Measurements, Recurring | Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	625	592
Fair Value, Measurements, Recurring | Equity Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale equity securities	29,420	25,772
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	828,919	754,920
Total	828,919	754,920
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	443,166	311,975
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	347,768	410,285
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 securities	8,565	6,888
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	29,420	25,772
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	725,462	260,797
Derivative assets	95	528
Total	725,557	261,325
Derivative liabilities	504	203
Total	504	203
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	123,187	51,664
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	258,304	42,382
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	254,413	54,149
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,615	97,307
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	979	4,751
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	4,339	9,952
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	625	592
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration	7,227	39,705
Total	$ 7,227	$ 39,705

Schedule of Reported Financial

Schedule of Reported Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,554,476	$ 1,016,245
Liabilities	7,731	39,908
Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	504	203
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	914,121	773,924
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	522,280	137,303
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	117,980	104,490
Prepayments and other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	95	528
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		9,106
Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	7,227	30,599
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	828,919	754,920
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	790,934	722,260
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	37,985	32,660
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	725,557	261,325
Liabilities	504	203
Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	504	203
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	123,187	51,664
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	522,280	137,303
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	79,995	71,830
Significant Other Observable Inputs (Level 2) | Prepayments and other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	95	528
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	7,227	39,705
Significant Unobservable Inputs (Level 3) | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		9,106
Significant Unobservable Inputs (Level 3) | Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	$ 7,227	$ 30,599

Schedule of Changes in Fair Val

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 39,705		$ 70,543
Acquisition of AutoGuide			23,976
Foreign currency impact	(355)		(967)
Payments	(8,852)	[1]	(34,590)	[2]
Fair value adjustment	(23,271)	[3]	(19,257)	[4]
Balance at end of period	$ 7,227		$ 39,705
[1]	During the year ended December 31, 2020, Teradyne paid $8.9 million of contingent consideration for the earn-out in connection with the acquisition of MiR.
[2]	During the year ended December 31, 2019, Teradyne paid $30.8 million and $3.8 million of contingent consideration for the earn-outs in connection with the acquisitions of MiR and Universal Robots A/S (“Universal Robots”), respectively.
[3]	During the year ended December 31, 2020, the fair value of contingent consideration for the earn-out in connection with the acquisition of AutoGuide was decreased by $19.7 million primarily due to a decrease in forecasted revenues. Teradyne has received a letter from the sellers of AutoGuide alleging non-compliance with the earn-out provisions of the AutoGuide acquisition agreement. Teradyne disputes the allegation of non-compliance. The ultimate amount of contingent consideration for the earn-outs in connection with the acquisition of AutoGuide may be affected by the outcome of the dispute. During the year ended December 31, 2020, the fair value of contingent consideration for the earn-out in connection with the acquisition of MiR was decreased by $3.5 million primarily due to a decrease in forecasted revenues.
[4]	During the year ended December 31, 2019, the fair value of contingent consideration for the earn-out in connection with the acquisition of MiR was decreased by $22.2 million primarily due to a decrease in forecasted revenues partially offset by the impact from modification of the earn-out structure. During the year ended December 31, 2019, the fair value of contingent consideration for the earn-out in connection with the acquisition of AutoGuide was increased by $3.0 million primarily due to an increase in forecasted revenues

Schedule of Changes in Fair V_2

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration									$ 8,852	$ 27,615	$ 13,571
Increase (decrease) in contingent consideration									(23,271)	(19,257)	$ 987
Universal Robots (UR)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration										30,800
Increase (decrease) in contingent consideration		$ 27,200	$ 29,900	$ 10,000		$ 7,800	$ 11,700	$ 3,000		3,800
Avionics Interface Technologies, LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration									8,900
MiR
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Increase (decrease) in contingent consideration									3,500	22,200
Autoguide LLC [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Increase (decrease) in contingent consideration	$ 15,300		$ 600		$ 3,000					$ 3,000
Autoguide LLC [Member] | Dispute In Respect Of Contingent Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Increase (decrease) in contingent consideration									$ 19,700

Quantitative Information Associ

Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Nov. 13, 2019	Dec. 31, 2018	Apr. 25, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration		$ 8,900	$ 24,000		$ 30,800
Mobile Industrial Robots (MiR)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration		$ 9,100		$ 31,000	$ 52,600
Monte Carlo Simulation | Revenue for the period July 1, 2015-December 31, 2018 | Mobile Industrial Robots (MiR)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Target achievement, volatility	16.50%
Discount rate	1.00%
Monte Carlo Simulation | Revenue for the period July 1, 2015-December 31, 2018 | Significant Unobservable Inputs (Level 3) | Mobile Industrial Robots (MiR)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 7,227

Schedule of Carrying Amounts an

Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Nov. 13, 2019	Apr. 25, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Marketable securities		$ 610,840	$ 216,021
Contingent consideration			8,900	$ 24,000	$ 30,800
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		914,121	773,924
Marketable securities		640,260	241,793
Derivative assets		95	528
Contingent consideration		7,227	39,705
Derivative liabilities		504	203
Convertible debt	[1]	410,111	394,687
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		914,121	773,924
Marketable securities		640,260	241,793
Derivative assets		95	528
Contingent consideration		7,227	39,705
Derivative liabilities		504	203
Convertible debt	[1]	$ 1,739,553	$ 1,010,275
[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	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 601,976	$ 211,596
Available-for-sale marketable securities, Unrealized Gain	9,077	4,687
Available-for-sale marketable securities, Unrealized (Loss)	(213)	(262)
Available-for-sale marketable securities, Fair Market Value	610,840	216,021
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	70,418	23,999
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	257,132	42,167
Available-for-sale marketable securities, Unrealized Gain	1,330	431
Available-for-sale marketable securities, Unrealized (Loss)	(158)	(216)
Available-for-sale marketable securities, Fair Market Value	258,304	42,382
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	17,243	17,556
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	254,404	54,124
Available-for-sale marketable securities, Unrealized Gain	10	26
Available-for-sale marketable securities, Unrealized (Loss)	(1)	(1)
Available-for-sale marketable securities, Fair Market Value	254,413	54,149
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	12,173	1,391
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	76,129	93,267
Available-for-sale marketable securities, Unrealized Gain	7,539	4,081
Available-for-sale marketable securities, Unrealized (Loss)	(53)	(41)
Available-for-sale marketable securities, Fair Market Value	83,615	97,307
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	39,896	2,009
Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	8,413	6,753
Available-for-sale marketable securities, Unrealized Gain	152	135
Available-for-sale marketable securities, Fair Market Value	8,565	6,888
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	4,294	9,942
Available-for-sale marketable securities, Unrealized Gain	46	14
Available-for-sale marketable securities, Unrealized (Loss)	(1)	(4)
Available-for-sale marketable securities, Fair Market Value	4,339	9,952
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,106	3,043
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	979	4,751
Available-for-sale marketable securities, Fair Market Value	979	4,751
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	625	592
Available-for-sale marketable securities, Fair Market Value	$ 625	$ 592

Schedule of Reported Available

Schedule of Reported Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 601,976	$ 211,596
Available-for-sale marketable securities, Unrealized Gain	9,077	4,687
Available-for-sale marketable securities, Unrealized (Loss)	(213)	(262)
Available-for-sale marketable securities, Fair Market Value	610,840	216,021
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	70,418	23,999
Marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	522,228	137,144
Available-for-sale marketable securities, Unrealized Gain	92	160
Available-for-sale marketable securities, Unrealized (Loss)	(40)	(1)
Available-for-sale marketable securities, Fair Market Value	522,280	137,303
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	61,806	2,922
Long-term marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	79,748	74,452
Available-for-sale marketable securities, Unrealized Gain	8,985	4,527
Available-for-sale marketable securities, Unrealized (Loss)	(173)	(261)
Available-for-sale marketable securities, Fair Market Value	88,560	78,718
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 8,612	$ 21,077

Contractual Maturities of Inves

Contractual Maturities of Investments in Debt Securities Held (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Schedule of Available-for-sale Securities
Due within one year, cost	$ 522,228
Due after 1 year through 5 years, cost	24,829
Due after 5 years through 10 years, cost	13,030
Due after 10 years, cost	33,476
Total, cost	593,563
Due within one year, fair market value	522,280
Due after 1 year through 5 years, fair market value	25,245
Due after 5 years through 10 years, fair market value	14,183
Due after 10 years, fair maket value	40,567
Total, fair market value	$ 602,275

Schedule of Notional Amount of

Schedule of Notional Amount of Derivatives (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	$ 56.3	$ 20.5
Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(48.3)	(62.2)
Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	104.6	82.7
Japanese Yen
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(14.1)	(29.3)
Japanese Yen | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(14.1)	(29.3)
Taiwan Dollar
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(27.9)	(18.4)
Taiwan Dollar | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(27.9)	(18.4)
Korean Won
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(5.3)	(10.7)
Korean Won | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(5.3)	(10.7)
British Pound Sterling
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(1)	(3.8)
British Pound Sterling | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(1)	(3.8)
Euro
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	43.9	47.8
Euro | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	43.9	47.8
Singapore Dollar
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	52.3	25.3
Singapore Dollar | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	52.3	25.3
Philippines, Pesos
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	5	5.2
Philippines, Pesos | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	5	5.2
China, Yuan Renminbi
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	3.4	4.4
China, Yuan Renminbi | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	$ 3.4	$ 4.4

Schedule of Derivative Instrume

Schedule of Derivative Instruments in Statement of Financial Position at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net	$ (409)	$ 325
Not Designated as Hedging Instrument | Foreign currency forward contracts | Prepayments
Derivatives, Fair Value [Line Items]
Derivative assets	95	528
Not Designated as Hedging Instrument | Foreign currency forward contracts | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (504)	$ (203)

Schedule of Effect of Derivativ

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Losses on derivatives recognized in statements of operations	$ 3,515	$ 5,960	$ 7,386

Schedule of Effect of Derivat_2

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on foreign currency transactions	$ (2.6)	$ 1.6	$ 2.5

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Total lease expense	$ 38.5	$ 35.6
Variable lease costs	12.1	11.1
Short-term leases	$ 3.4	$ 2.6
Operating Lease, Weighted Average Remaining Lease Term	4 years 2 months 12 days	4 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	4.80%	5.00%

Supplemental Cash Flow Informat

Supplemental Cash Flow Information Related to Leases (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	$ 24,136
Right-of-use assets obtained in exchange for new lease obligations	$ 14,801

Schedule of Operating Lease, Ma

Schedule of Operating Lease, Maturity (Detail) $ in Thousands	Dec. 31, 2020USD ($)
2021	$ 22,451
2022	16,798
2023	9,727
2024	7,215
2025	5,715
Thereafter	6,149
Total lease payments	68,055
Less imputed interest	(5,409)
Total lease liabilities	$ 62,646

Debt - Additional Information (

Debt - Additional Information (Detail)	Feb. 22, 2021USD ($)Holders	May 01, 2020USD ($)	Dec. 12, 2016USD ($)Customershares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2016USD ($)	Apr. 27, 2015USD ($)
Debt Instrument
Repurchase of common stock				$ 88,465,000	$ 500,000,000	$ 823,478,000
Line of Credit Facility, Maximum Borrowing Capacity		$ 400,000,000
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases		$ 150,000,000
Line of Credit Facility, Interest Rate Description		The interest rate applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.50% to 1.25% per annum or LIBOR, a minimum of 0.75%, plus a margin ranging from 1.50% to 2.25% per annum, based on the consolidated leverage ratio of Teradyne. In addition, Teradyne will pay a commitment fee on the unused portion of the commitments under the Credit Facility ranging from 0.25% to 0.40% per annum, based on the then applicable consolidated leverage ratio.
Term of revolving credit facility				3 years
Convertible common shares				$ 3,787,000
Convertible Common Shares [Member]
Debt Instrument
Convertible common shares				37,000,000
Collateral Pledged [Member]
Debt Instrument
Line of Credit Facility, Interest Rate Description		65
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Aggregate principal amount			$ 460,000,000	459,971,000	$ 460,000,000
Debt instrument, interest rate, stated percentage			1.25%
Debt instrument, net proceeds after issuance costs			$ 450,800,000
Payment for net cost of convertible note hedges net of warrant proceeds			33,000,000	$ 33,000,000
Repurchase of common stock			$ 50,100,000
Repurchase of stock, shares | shares			2,000,000
Senior notes maturity date			Dec. 15, 2023
Debt instrument, frequency of periodic payment			payable semiannually in arrears on June 15 and December 15 of each year
Debt instrument, conversion option expiration date			Sep. 15, 2023
Debt instrument conversion price | $ / shares				$ 31.56
Shares that would be issued upon conversion | shares				14,600,000
Strike price per share of warrant | $ / shares				$ 39.60
Debt instrument, convertible, carrying amount of equity component				$ 100,800,000
Debt instrument, effective annual interest rate				5.00%
Financing cost				$ 3,300,000			$ 7,200,000
Debt issuance costs, amortization period				7 years
Unamortized discount				$ 49,900,000
Debt Instrument, convertible, remaining discount amortization period				3 years
Value of notes converted				$ 1,747,500,000
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Subsequent Event
Debt Instrument
Number of holders excerised the conversion option | Holders	24
Debt instrument conversion converted instrument amount	$ 51,000,000
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option one
Debt Instrument
Trading days measurement period | Customer			20
Consecutive trading days measurement period | Customer			30
Percentage of conversion price			130.00%
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option two
Debt Instrument
Aggregate principal amount			$ 1,000,000
Trading days measurement period | Customer			5
Consecutive trading days measurement period | Customer			5
Percentage of closing sale price of common stock and conversion rate product			98.00%
Revolving Credit Facility
Debt Instrument
Term of loan, years				5 years
Credit facility, borrowing capacity								$ 350,000,000
Revolving Credit Facility | Maximum | Truist Bank [Member]
Debt Instrument
Commitment fee percentage of unused portion of credit facility				0.40%
Revolving Credit Facility | Minimum | Truist Bank [Member]
Debt Instrument
Commitment fee percentage of unused portion of credit facility				0.25%
Revolving Credit Facility | Base Rate | Maximum | Truist Bank [Member]
Debt Instrument
Debt instrument, basis spread on variable rate				1.25%
Revolving Credit Facility | Base Rate | Minimum | Truist Bank [Member]
Debt Instrument
Debt instrument, basis spread on variable rate				0.50%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Truist Bank [Member]
Debt Instrument
Debt Instrument Base Rate Percentage				0.75%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum | Truist Bank [Member]
Debt Instrument
Debt instrument, basis spread on variable rate				2.25%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum | Truist Bank [Member]
Debt Instrument
Debt instrument, basis spread on variable rate				1.50%

Components of Convertible Senio

Components of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 12, 2016
Debt Instrument
Current debt	$ 33,343
Long-term debt	376,768	$ 394,687
Net carrying amount of convertible debt	410,111	394,687
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Debt principal	459,971	460,000	$ 460,000
Unamortized discount	49,860	65,313
Net carrying amount of convertible debt	$ 410,111	$ 394,687

Interest Expense on Convertible

Interest Expense on Convertible Senior Notes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument
Contractual interest expense on the coupon	$ 5,750	$ 5,750
Amortization of the discount component and debt issue fees recognized as interest expense	15,454	14,706
Total interest expense on the convertible debt	$ 21,204	$ 20,456

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,480,158	$ 1,522,354	$ 1,953,646
Other comprehensive income (loss)	52,370	(5,814)	(29,460)
Balance	2,207,018	1,480,158	1,522,354
Foreign Currency Translation Reclassification Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(23,514)	(12,523)
Other comprehensive loss before reclassifications, net of tax	48,903	(10,991)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0	0
Other comprehensive income (loss)	48,903	(10,991)
Balance	25,389	(23,514)	(12,523)
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	3,480	(1,845)
Other comprehensive loss before reclassifications, net of tax	5,839	6,015
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(2,365)	(690)
Other comprehensive income (loss)	3,474	5,325
Balance	6,954	3,480	(1,845)
Amortization of Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	1,180	1,328
Other comprehensive loss before reclassifications, net of tax	0	0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(7)	(148)	(245)
Other comprehensive income (loss)	(7)	(148)
Balance	1,173	1,180	1,328
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(18,854)	(13,040)	18,776
Other comprehensive loss before reclassifications, net of tax	54,742	(4,976)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(2,372)	(838)	1,092
Other comprehensive income (loss)	52,370	(5,814)	(29,460)
Balance	$ 33,516	$ (18,854)	$ (13,040)

Changes in Accumulated Other _2

Changes in Accumulated Other Comprehensive (Loss) Income (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss), tax	$ (667)	$ (235)	$ (92)
Foreign currency translation adjustments, tax	0	0	0
Unrealized (losses) gains on marketable securities, tax	1,910	946	(521)
Retirement plans prior service benefit, tax	(1,126)	(1,124)	(1,081)
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 (loss), tax	0	0
Other comprehensive income (loss), tax	0	0
Unrealized (Losses) Gains on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, tax	1,629	1,659
Amounts reclassified from accumulated other comprehensive income (loss), tax	(665)	(192)	(21)
Other comprehensive income (loss), tax	964	1,467
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 (loss), tax	(2)	(43)	$ (71)
Other comprehensive income (loss), tax	$ (2)	$ (43)

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income (expense)	$ 2,365	$ 690	$ (1,337)
Amortization of Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax	7	148	245
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax	$ 2,372	$ 838	$ (1,092)

Reclassifications Out of Accu_2

Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 667	$ 235	$ 92
Unrealized (Losses) Gains on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	665	192	21
Amortization of Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 2	$ 43	$ 71

Goodwill and Intangible Asset_2

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

3 Months Ended

12 Months Ended

Dec. 31, 2020

[1],[2]

Sep. 27, 2020

[2],[3]

Jun. 28, 2020

[2],[4]

Mar. 29, 2020

[5]

Dec. 31, 2019

Sep. 30, 2019

[9]

Jun. 30, 2019

[10]

Mar. 31, 2019

[11]

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Line Items]

Acquired intangible assets amortization

$ 5,752

$ 6,219

$ 8,941

$ 9,891

$ 9,784

[6],[7],[8]

$ 9,647

$ 10,083

$ 10,634

$ 30,803

$ 40,147

$ 39,191

MiR Reporting Unit Percentage

14.00%

14.00%

MiR Goodwill Amount

$ 123,600

$ 123,600

[1]

Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.

[2]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[3]

Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.

[4]

Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.

[5]

Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.

[6]

Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.

[7]

Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.

[8]

Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[9]

Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[10]

Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[11]

Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

Changes in Carrying Amount of G

Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill acquisition		$ 1,428
Foreign currency translation adjustment	$ 37,577	(8,219)
Goodwill	1,216,425	1,178,997	$ 1,144,416
Accumulated impairment losses	(762,566)	(762,566)	(762,566)
Goodwill	453,859	416,431	381,850
Autoguide LLC
Goodwill [Line Items]
Goodwill acquisition	(149)	41,372
Goodwill	41,223
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	37,418	(8,247)
Goodwill	433,752	396,483	363,358
Goodwill	433,752	396,483	363,358
Industrial Automation | Autoguide LLC
Goodwill [Line Items]
Goodwill acquisition	(149)	41,372
Wireless Test
Goodwill [Line Items]
Goodwill	361,819	361,819	361,819
Accumulated impairment losses	(353,843)	(353,843)	(353,843)
Goodwill	7,976	7,976	7,976
Semiconductor Test
Goodwill [Line Items]
Goodwill acquisition		1,428
Foreign currency translation adjustment	159	28
Goodwill	262,155	261,996	260,540
Accumulated impairment losses	(260,540)	(260,540)	(260,540)
Goodwill	1,615	1,456
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)	(148,183)
Goodwill	$ 10,516	$ 10,516	$ 10,516

Schedule of Amortizable Intangi

Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 408,906	$ 507,836
Accumulated Amortization	(307,347)	(375,008)
Foreign Currency Translation Adjustment	(620)	(7,348)
Net Carrying Amount	100,939	125,480
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	272,547	361,787
Accumulated Amortization	(210,479)	(279,000)
Foreign Currency Translation Adjustment	(1,610)	(5,709)
Net Carrying Amount	60,458	77,078
Customer Relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	66,239	75,669
Accumulated Amortization	(54,524)	(59,077)
Foreign Currency Translation Adjustment	305	(455)
Net Carrying Amount	12,020	16,137
Trademarks and tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	70,120	70,120
Accumulated Amortization	(42,344)	(36,671)
Foreign Currency Translation Adjustment	685	(1,184)
Net Carrying Amount	$ 28,461	32,265
Backlog
Finite-Lived Intangible Assets
Gross Carrying Amount		260
Accumulated Amortization		$ (260)

Schedule of Amortizable Intan_2

Schedule of Amortizable Intangible Assets (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Finite-Lived Intangible Assets
Impairment of intangible assets	$ 98.9

Schedule of Estimated Intangibl

Schedule of Estimated Intangible Asset Amortization Expense (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Finite-Lived Intangible Assets
2021	$ 21,893
2022	21,000
2023	20,504
2024	20,192
2025	11,922
Thereafter	$ 5,428

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments	$ 603.5
Purchase commitments less than one year	$ 592.1
Warranty period	1 year
Product warranty accrual	$ 16.6	$ 9
Revenue deferrals related to extended warranties	$ 51.9	$ 30.7

Computation of Basic and Dilute

Computation of Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2020	[1],[2]	Sep. 27, 2020	[2],[3]	Jun. 28, 2020	[2],[4]	Mar. 29, 2020	[5]	Dec. 31, 2019	[6],[7],[8]	Sep. 30, 2019	[9]	Jun. 30, 2019	[10]	Mar. 31, 2019	[11]	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Income Loss Per Common Share
Net income for basic and diluted net income per share	$ 196,330		$ 222,718		$ 188,908		$ 176,191		$ 125,075		$ 135,860		$ 97,397		$ 109,138		$ 784,147	$ 467,468	$ 451,779
Weighted average common shares-basic																	166,120	170,425	187,672
Incremental shares from assumed conversion of convertible notes																	8,528	4,909	2,749
Convertible note hedge warrant shares																	6,989	2,698	485
Employee stock purchase rights																	10	13	36
Dilutive potential common shares																	16,922	9,034	4,933
Weighted average common shares-diluted																	183,042	179,459	192,605
Net income per common share-basic	$ 1.18		$ 1.34		$ 1.14		$ 1.06		$ 0.75		$ 0.80		$ 0.57		$ 0.63		$ 4.72	$ 2.74	$ 2.41
Net income per common share-diluted	$ 1.05		$ 1.21		$ 1.05		$ 0.97		$ 0.69		$ 0.75		$ 0.55		$ 0.62		$ 4.28	$ 2.60	$ 2.35
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements																	1,264	1,236	1,385
Stock Options
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements																	131	178	278
[1]	Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[3]	Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.
[4]	Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.
[5]	Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.
[6]	Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.
[7]	Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.
[8]	Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[9]	Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[10]	Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[11]	Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

Computation of Basic and Dilu_2

Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail) shares in Millions	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Convertible Notes
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 31.56
Shares that would be issued upon conversion | shares	14.6
Convertible Notes Hedge Warrant
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 39.60
Shares that would be issued upon conversion | shares	14.6

Net Income Per Common Share - A

Net Income Per Common Share - Additional Information (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Employee Stock Option [Member]
Net Income Loss Per Common Share
Exercise of stock options	0.1
Restricted Stock Units (RSUs) [Member]
Net Income Loss Per Common Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.1	0.5

Restructuring and Other - Addit

Restructuring and Other - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve
Contingent consideration adjustment										$ (23,271)	$ (19,257)	$ 987
Severance benefit and charges		$ 1,100	$ 1,100		$ 700	$ 500	$ 800	$ 800	$ 800
Acquisition related costs			500	$ 3,100	1,400	200	500	500	1,300
Semiconductor Test
Restructuring Cost and Reserve
Contingent consideration adjustment										3,500
Severance benefit and charges	$ 500									2,300
Acquisition related costs										2,500	2,500
Contract termination settlement fee										4,000
AutoGuide
Restructuring Cost and Reserve
Contingent consideration adjustment											3,000
Universal Robots (UR)
Restructuring Cost and Reserve
Contingent consideration adjustment			$ 27,200	$ 29,900	$ 10,000		$ 7,800	$ 11,700	$ 3,000		3,800
Mobile Industrial Robots (MiR)
Restructuring Cost and Reserve
Contingent consideration adjustment						$ 5,800
Semiconductor Test, Industrial Automation and Corporate
Restructuring Cost and Reserve
Severance benefit and charges											2,900
Restructuring and other										1,200
Semiconductor Test, Industrial Automation and Corporate | Mobile Industrial Robots (MiR)
Restructuring Cost and Reserve
Contingent consideration adjustment											$ 22,200
TER Corporate And Eliminations | Universal Robots (UR)
Restructuring Cost and Reserve
Contingent consideration adjustment										$ 19,700

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)Participant	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure
Number of retiree participants | Participant					115
Defined Benefit Plan, decrease in benefit obligation					$ 4,000
Defined Benefit Plan, decrease in plan assets					24,400
Actrual loss on benefit obligations	$ (7,700)	$ (2,700)	$ (100)	$ (7,700)		$ 29,000
Gain (Loss) Due to Settlement					(500)
Fair value of pension plans assets totaled	160,700				160,700
UNITED STATES
Defined Benefit Plan Disclosure
Actrual loss on benefit obligations					(24,671)	(24,447)
Accumulated benefit obligation for defined benefit pension plans	$ 196,700			$ 198,200	$ 196,700	$ 198,200
Percentage of expected return on plan assets assumption					3.00%	4.30%	4.30%
Discount rate utilized to determine future pension obligations	2.20%			3.00%	2.20%	3.00%
Fair value of pension plans assets totaled	$ 158,855			$ 166,932	$ 158,855	$ 166,932	$ 144,301
Contribution to defined benefit pension plans					3,098	2,805
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Actrual loss on benefit obligations					(2,951)	(4,520)
Accumulated benefit obligation for defined benefit pension plans	$ 46,500			$ 39,900	$ 46,500	$ 39,900
Percentage of expected return on plan assets assumption					3.80%	2.00%	1.50%
Discount rate utilized to determine future pension obligations	0.70%			1.10%	0.70%	1.10%
Fair value of pension plans assets totaled	$ 1,856			$ 1,586	$ 1,856	$ 1,586	$ 1,400
Contribution to defined benefit pension plans					1,079	923
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Defined Benefit Plan, decrease in benefit obligation					27,600
Actrual loss on benefit obligations					$ (421)	$ (717)
Discount rate utilized to determine future pension obligations	2.20%			3.00%	2.20%	3.00%	4.00%
Fair value of pension plans assets totaled	$ 0			$ 0	$ 0	$ 0
Contribution to defined benefit pension plans					$ 1,205	$ 1,358
United States Plans
Defined Benefit Plan Disclosure
Percentage of expected return on plan assets assumption					3.00%
Discount rate utilized to determine future pension obligations	2.30%			3.10%	2.30%	3.10%
Fair value of pension plans assets totaled	$ 158,900				$ 158,900
U.S. Supplemental Executive Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans					3,100	$ 2,800
Contribution to defined benefit pension plans in 2018	3,300				3,300
Non-United States Subsidiaries
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans					1,100	$ 900
Contribution to defined benefit pension plans in 2018	1,100				1,100
Taiwan Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Fair value of pension plans assets totaled	$ 1,900				$ 1,900

Schedule of Defined Benefit Pen

Schedule of Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligation (Detail) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure
Actuarial loss	$ 7,700	$ 2,700	$ 100	$ 7,700		$ (29,000)
Ending Balance	160,700				$ 160,700
UNITED STATES
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year					203,791	178,237
Service cost					1,773	1,608	$ 2,196
Interest cost					5,770	7,189	8,940
Actuarial loss					24,671	24,447
Benefits paid					(9,844)	(7,690)
Retiree annuity purchase					(24,379)
Liability loss due to settlement					451
Non-U.S. currency movement					0
Projected benefit obligation, End of year	202,233			203,791	202,233	203,791	178,237
Beginning Balance					166,932	144,301
Actual return on plan assets					23,048	27,516
Company contributions					3,098	2,805
Benefits paid					(9,844)	(7,690)
Retiree annuity purchase					(24,379)
Non-U.S. currency movement					0
Ending Balance	158,855			166,932	158,855	166,932	144,301
Funded status	(43,378)			(36,859)	(43,378)	(36,859)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year					43,952	39,146
Service cost					907	751	786
Interest cost					516	691	687
Actuarial loss					2,951	4,520
Benefits paid					(1,299)	(836)
Retiree annuity purchase					0
Liability loss due to settlement					0
Non-U.S. currency movement					3,961	(320)
Projected benefit obligation, End of year	50,988			43,952	50,988	43,952	39,146
Beginning Balance					1,586	1,400
Actual return on plan assets					67	64
Company contributions					1,079	923
Benefits paid					(988)	(836)
Retiree annuity purchase					0
Non-U.S. currency movement					112	35
Ending Balance	1,856			1,586	1,856	1,586	1,400
Funded status	(49,132)			(42,366)	(49,132)	(42,366)
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year					9,003	9,256
Service cost					57	41	39
Interest cost					240	347	196
Actuarial loss					421	717
Benefits paid					(1,205)	(1,358)
Projected benefit obligation, End of year	8,515			9,003	8,515	9,003	$ 9,256
Beginning Balance					0
Company contributions					1,205	1,358
Benefits paid					(1,205)	(1,358)
Ending Balance	0			0	0	0
Funded status	$ (8,515)			$ (9,003)	$ (8,515)	$ (9,003)

Schedule of Amounts Recorded wi

Schedule of Amounts Recorded within Statements of Financial Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Retirement plans assets	$ 17,468	$ 18,457
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Retirement plans assets	17,468	18,457
Accrued employees' compensation and withholdings	(3,273)	(2,826)
Retirement plans liabilities	(57,573)	(52,490)
Funded status	(43,378)	(36,859)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Retirement plans assets	0
Accrued employees' compensation and withholdings	(1,019)	(922)
Retirement plans liabilities	(48,113)	(41,444)
Funded status	(49,132)	(42,366)
Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Accrued employees' compensation and withholdings	(1,161)	(1,231)
Retirement plans liabilities	(7,354)	(7,772)
Funded status	$ (8,515)	$ (9,003)

Schedule of Amounts Recognized

Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
UNITED STATES
Defined Benefit Plan Disclosure
Deferred taxes related to prior service cost recognized in other comprehensive income	$ 560	$ 560
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Deferred taxes related to prior service cost recognized in other comprehensive income	0
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Prior service cost, before tax	(49)	(58)
Deferred taxes	(1,686)	(1,684)
Deferred taxes related to prior service cost recognized in other comprehensive income	$ (1,735)	$ (1,742)

Schedule of Pension Plans with

Schedule of Pension Plans with Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
UNITED STATES
Defined Benefit Plan Disclosure
Projected benefit obligation	$ 60.8	$ 55.3
Accumulated benefit obligation	58.5	53.2
Fair value of plan assets	0
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation	51	44
Accumulated benefit obligation	46.5	39.9
Fair value of plan assets	$ 1.9	$ 1.6

Schedule of Net Periodic Pensio

Schedule of Net Periodic Pension and Postretirement (income) Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure
Net actuarial loss (gain)	$ 10,284	$ 8,176	$ (3,316)
UNITED STATES
Defined Benefit Plan Disclosure
Service cost	1,773	1,608	2,196
Interest cost	5,770	7,189	8,940
Expected return on plan assets	(4,840)	(6,042)	(9,049)
Amortization of prior service cost			58
Net actuarial loss (gain)	6,463	2,973	(4,429)
Settlement loss	451		345
Total net periodic pension cost	9,617	5,728	(1,939)
Prior service cost			(58)
Total recognized in other comprehensive income			(58)
Total recognized in net periodic pension cost (income) and other comprehensive income	9,617	5,728	(1,997)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	907	751	786
Interest cost	516	691	687
Expected return on plan assets	(65)	(29)	(19)
Net actuarial loss (gain)	2,949	4,485	743
Settlement loss	0
Total net periodic pension cost	4,307	5,898	2,197
Prior service cost	0
Total recognized in other comprehensive income	0
Total recognized in net periodic pension cost (income) and other comprehensive income	4,307	5,898	2,197
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Service cost	57	41	39
Interest cost	240	347	196
Amortization of prior service cost	(9)	(191)	(373)
Net actuarial loss (gain)	421	717	25
Special termination benefits	0		3,708
Total net periodic pension cost	709	914	3,595
Prior service cost	9	191	373
Total recognized in other comprehensive income	9	191	373
Total recognized in net periodic pension cost (income) and other comprehensive income	$ 718	$ 1,105	$ 3,968

Schedule of Weighted Average -

Schedule of Weighted Average - Assumptions to Determine Net Periodic Pension Cost (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
UNITED STATES
Defined Benefit Plan Disclosure
Discount rate	2.80%	4.10%	3.40%
Expected return on plan assets	3.00%	4.30%	4.30%
Salary progression rate	2.60%	2.30%	2.30%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	1.10%	1.80%	1.80%
Expected return on plan assets	3.80%	2.00%	1.50%
Salary progression rate	2.50%	2.50%	2.70%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	3.00%	4.00%	3.40%
Initial health care cost trend rate	7.10%	7.50%	7.90%
Ultimate health care cost trend rate	4.50%	4.50%	4.50%
Year in which ultimate health care cost trend rate is reached	2026	2026	2026

Schedule of Weighted Average As

Schedule of Weighted Average Assumptions to Determine Pension Obligations (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	2.20%	3.00%	4.00%
Initial medical trend	7.30%	7.10%	7.50%
Ultimate health care trend	4.50%	4.50%	4.50%
Medical cost trend rate decrease to ultimate rate in year	2029	2026	2026
UNITED STATES
Defined Benefit Plan Disclosure
Discount rate	2.20%	3.00%
Salary progression rate	2.40%	2.60%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	0.70%	1.10%
Salary progression rate	2.30%	2.50%

Schedule of Weighted Average Pe

Schedule of Weighted Average Pension Assets Allocations by Category (Detail)	Dec. 31, 2020	Dec. 31, 2019
UNITED STATES
Defined Benefit Plan Disclosure
Total	100.00%	100.00%
UNITED STATES | Fixed income securities
Defined Benefit Plan Disclosure
Total	94.00%	94.00%
UNITED STATES | Equity securities
Defined Benefit Plan Disclosure
Total	5.00%	5.00%
UNITED STATES | Other than Securities Investment
Defined Benefit Plan Disclosure
Total	1.00%	1.00%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	100.00%	100.00%
Foreign Pension Plans, Defined Benefit | Other than Securities Investment
Defined Benefit Plan Disclosure
Total	100.00%	100.00%

Schedule of Target Assets Alloc

Schedule of Target Assets Allocation (Detail)	Dec. 31, 2020
Bloomberg Barclays Corporate or Better Index | U.S. corporate fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	75.00%
MSCI World Minimum Volatility Index | Global equity Securities
Defined Benefit Plan Disclosure
Target assets allocation percentage	5.00%
Bloomberg Barclays Long Government Bond Index | U.S. government fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	14.00%
Bloomberg Barclays High Yield Index | High yield fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	5.00%
Citigroup Three Month Treasury Bill Index | Cash
Defined Benefit Plan Disclosure
Target assets allocation percentage	1.00%

Schedule of Fair Value of Pensi

Schedule of Fair Value of Pensions Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure
Total	$ 160,700
UNITED STATES
Defined Benefit Plan Disclosure
Total	158,855	$ 166,932	$ 144,301
UNITED STATES | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	1,582	1,610
UNITED STATES | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	157,273	165,322
UNITED STATES | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Corporate Debt Securities
Defined Benefit Plan Disclosure
Total	127,098	133,792
UNITED STATES | Corporate Debt Securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Corporate Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	127,098	133,792
UNITED STATES | Corporate Debt Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | US Government Debt Securities
Defined Benefit Plan Disclosure
Total	22,250	23,186
UNITED STATES | US Government Debt Securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | US Government Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	22,250	23,186
UNITED STATES | US Government Debt Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Global equity Securities
Defined Benefit Plan Disclosure
Total	7,925	8,344
UNITED STATES | Global equity Securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Global equity Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	7,925	8,344
UNITED STATES | Global equity Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Other
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Other | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Cash and Cash Equivalents
Defined Benefit Plan Disclosure
Total	1,582	1,610
UNITED STATES | Cash and Cash Equivalents | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	1,582	1,610
UNITED STATES | Cash and Cash Equivalents | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	0
UNITED STATES | Cash and Cash Equivalents | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	1,856	1,586	$ 1,400
Foreign Pension Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	1,856	1,586
Foreign Pension Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Corporate Debt Securities
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Corporate Debt Securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Corporate Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Corporate Debt Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | US Government Debt Securities
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | US Government Debt Securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | US Government Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | US Government Debt Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Global equity Securities
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Global equity Securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Global equity Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Global equity Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Other
Defined Benefit Plan Disclosure
Total	1,856	1,586
Foreign Pension Plans, Defined Benefit | Other | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	1,856	$ 1,586
Foreign Pension Plans, Defined Benefit | Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	0
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	$ 0

Schedule of Expected Future Ben

Schedule of Expected Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2020USD ($)
UNITED STATES
Defined Benefit Plan Disclosure
2021	$ 8,902
2022	8,782
2023	9,189
2024	9,815
2025	10,374
2026-2030	54,145
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
2021	1,058
2022	1,063
2023	1,313
2024	1,192
2025	1,140
2026-2030	7,053
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
2021	1,161
2022	961
2023	786
2024	646
2025	533
2026-2030	$ 1,601

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended						12 Months Ended
	Jan. 31, 2021	Jul. 31, 2020	Jan. 31, 2020	Jul. 31, 2019	Jan. 31, 2019	Jul. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Total shareholder return performance measurement period							3 years
Restricted stock unit awards granted							616,000	1,139,000	790,000
Weighted average grant date fair value of restricted stock units granted							$ 72,760	$ 39,080	$ 45,990
Stock price							$ 72.61	$ 37.95	$ 47.70
Tax benefit from compensation expense							$ 13,060,000	$ 8,360,000	$ 12,036,000
Total unrecognized expense related to non-vested restricted stock unit awards and stock options							$ 44,000,000
Unrecognized expense related to non-vested restricted stock unit awards and stock options expected to be recognized over weighted average period, in years							2 years 4 months 24 days
Maximum percent of shares allowed to purchase							10.00%
Fair market value							$ 25,000
Maximum number of shares allowed to purchase							6,000
Percentage of common stock price paid							85.00%
Common stock issued to employees		200,000	200,000	300,000	400,000	300,000
Value of common stock issued to employees per share		$ 71.83		$ 40.72		$ 32.36	$ 101.91	$ 57.96	$ 26.67
Number of shares available for grant							6,123,000	6,727,000	7,874,000	8,605,000
Stock Based Compensation Relating To Retirement Agreement							$ 44,906,000	$ 37,897,000	$ 33,577,000
Retirement Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Stock Based Compensation Relating To Retirement Agreement							2,100,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Cash received from employees, employee stock options exercises							3,800,000	3,700,000	1,000,000
Tax benefit from compensation expense							$ 1,500,000	$ 2,000,000	$ 400,000
Percentage of common stock price paid							100.00%
Stock Options | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal installments							4 years
Stock Options | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal installments							7 years
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted							616,000	1,139,000	790,000
Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal 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 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
Share-based compensation arrangement by share-based payment award, description							capped at four times the grant date value for grants prior to 2019
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							100,000	100,000	100,000
Weighted average grant date fair value of restricted stock units granted							$ 89.93	$ 51.51	$ 54.85
Stock price							72.10	37.95	47.70
TSR Performance-Based Restricted Stock Units | Measurement Input, Expected Dividend Payment [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Estimated annual dividend amount per share							$ 0.40	$ 0.36	$ 0.36
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved							200.00%
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved							0.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares available for grant							1,400,000
PBIT Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted							100,000	100,000	100,000
Weighted average grant date fair value of restricted stock units granted							$ 70.94	$ 36.88	$ 46.62
Service-Based Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted							400,000	800,000	600,000
Weighted average grant date fair value of restricted stock units granted							$ 71.31	$ 37.65	$ 45.92
Service-Based Restricted Stock Units | Non Employee Directors And Certain Employees
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted							100,000	100,000	100,000
Weighted average grant date fair value of restricted stock units granted							$ 66.56	$ 48.03	$ 35.81
Service-Based Restricted Stock Units | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted							100,000	100,000	100,000
Weighted average grant date fair value of restricted stock units granted							$ 20.93	$ 10.64	$ 12.17
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued to employees	100,000

Schedule of Estimated Fair Valu

Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail) - TSR Performance-Based Restricted Stock Units	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rate	1.50%	2.60%	2.20%
Expected historical volatility	34.90%	31.90%	26.80%
Dividend yield	0.60%	1.00%	0.80%
New York Stock Exchange Composite Index
Share-based Compensation Arrangement by Share-based Payment Award
Expected historical volatility	11.40%	11.90%	12.40%

Schedule of Estimated Fair Va_2

Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Expected life (years)	5 years	5 years	5 years
Risk-free interest rate	1.50%	2.50%	2.40%
Volatility-historical	32.00%	30.10%	26.40%
Dividend yield	0.50%	1.00%	0.80%

Schedule of Stock Compensation

Schedule of Stock Compensation Plan Activity (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Awarded	616	1,139	790
Forfeited	(68)	(87)	(128)
Outstanding at January 1	319	506	531
Granted	56	102	69
Exercised	(159)	(280)	(94)
Forfeited		(7)
Expired		(2)
Outstanding at December 31	216	319	506
Vested and expected to vest at December 31	216	319	506
Exercisable at December 31	27	85	256
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Non-vested at January 1	2,269	2,454	3,174
Awarded	616	1,139	790
Vested	(1,028)	(1,237)	(1,382)
Forfeited	(68)	(87)	(128)
Non-vested at December 31	1,789	2,269	2,454

Schedule of Share Based Compens

Schedule of Share Based Compensation Total Shares Available (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Available for grant at January 1	6,727	7,874	8,605
Options granted	(56)	(102)	(69)
Options forfeited		7
Restricted stock units awarded	(616)	(1,139)	(790)
Restricted stock units forfeited	68	87	128
Available for grant at December 31	6,123	6,727	7,874

Schedule of Weighted-Average Re

Schedule of Weighted-Average Restricted Stock Unit Award Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Non-vested at January 1	$ 35,580	$ 29,220	$ 21,710
Awarded	72,760	39,080	45,990
Vested	31,530	23,590	20,200
Forfeited	45,360	35,600	24,670
Non-vested at December 31	$ 47,840	$ 35,580	$ 29,220

Schedule of Restricted Stock Un

Schedule of Restricted Stock Unit Awards Aggregate Intrinsic Value (Detail) - Restricted Stock Units - USD ($) $ / shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Vested	$ 71,582	$ 46,110	$ 63,688
Outstanding	$ 214,509	$ 154,752	$ 77,015
Expected to vest	$ 210,301	$ 152,374	$ 77,187

Schedule of Restricted Stock _2

Schedule of Restricted Stock Units Weighted Average Remaining Contractual Terms (Detail) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	11 months 15 days	1 year 7 days	11 months 1 day
Expected to vest	11 months 15 days	1 year 7 days	10 months 28 days

Schedule of Weighted Average St

Schedule of Weighted Average Stock Options Exercise Price (Detail)	12 Months Ended
	Dec. 31, 2020$ / shares
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding at January 1	$ 29.91
Options granted	72.61
Options exercised	23.77
Options forfeited
Options cancelled
Outstanding at December 31	45.59
Exercisable at December 31	$ 23.51

Schedule of Stock Option Aggreg

Schedule of Stock Option Aggregated Intrinsic Value Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Exercised	$ 9,682	$ 9,232	$ 2,960
Outstanding	16,083	12,218	7,359
Vested and expected to vest	13,499	7,701	7,359
Exercisable	$ 2,584	$ 4,517	$ 5,905

Schedule of Stock Options Weigh

Schedule of Stock Options Weighted Average Remaining Contractual Terms (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	4 years 7 months 6 days	4 years 2 months 12 days	3 years 7 months 6 days
Vested and expected to vest	4 years 10 months 24 days	5 years	3 years 7 months 6 days
Exercisable	2 years 6 months	2 years 1 month 6 days	2 years 4 months 24 days

Stock Based Compensation (Detai

Stock Based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 44,906	$ 37,897	$ 33,577
Income tax benefit	(13,060)	(8,360)	(12,036)
Total stock-based compensation expense after income taxes	31,846	29,537	21,541
Cost Of Revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	4,227	3,480	3,129
Engineering And Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	12,039	9,913	9,181
Selling and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 28,640	$ 24,504	$ 21,267

Savings Plan - Additional Infor

Savings Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Savings Plan [Line Items]
Savings plan maximum percentage of employees contribution allowable	20.00%
Percentage of employer contributions vested per year	25.00%
Maximum employment period considered for vesting of employers' contribution, in years	4 years
Liability, Retirement and Postemployment Benefits	$ 38	$ 32.7
U.S. Qualified Pension Plan
Savings Plan [Line Items]
Maximum percentage of matching contributions made by the employer	100.00%	100.00%	100.00%
Percentage of employer match on employee contribution	4.00%	4.00%	4.00%
Savings Plan
Savings Plan [Line Items]
Amounts charged to statements of operations	$ 21.7	$ 20.9	$ 19.4

Schedule of Income (Loss) Befor

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

3 Months Ended

12 Months Ended

Dec. 31, 2020

[1],[2]

Sep. 27, 2020

[2],[3]

Jun. 28, 2020

[2],[4]

Mar. 29, 2020

[5]

Dec. 31, 2019

[6],[7],[8]

Sep. 30, 2019

[9]

Jun. 30, 2019

[10]

Mar. 31, 2019

[11]

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Income Tax Disclosure [Line Items]

U.S.

$ 312,153

$ 192,442

$ 189,691

Non-U.S.

588,862

333,330

278,110

Income before income taxes

$ 222,925

$ 263,731

$ 217,291

$ 197,069

$ 148,886

$ 151,733

$ 131,177

$ 93,979

$ 901,015

$ 525,772

$ 467,801

[1]

Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.

[2]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[3]

Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.

[4]

Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.

[5]

Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.

[6]

Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.

[7]

Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.

[8]

Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[9]

Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[10]

Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[11]

Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

Schedule of Provision (Benefit)

Schedule of Provision (Benefit) for Income Taxes from Operations (Detail) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2020

[1],[2]

Sep. 27, 2020

[2],[3]

Jun. 28, 2020

[2],[4]

Mar. 29, 2020

[5]

Dec. 31, 2019

[6],[7],[8]

Sep. 30, 2019

[9]

Jun. 30, 2019

[10]

Mar. 31, 2019

[11]

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Income Tax Disclosure [Line Items]

Current, U.S. Federal

$ 58,678

$ 19,297

$ (59,122)

Current, Non-U.S.

75,193

52,810

45,083

Current, State

(1,315)

(4,347)

1,721

Current, Total

132,556

67,760

(12,318)

Deferred, U.S. Federal

(12,604)

(4,522)

29,252

Deferred, Non-U.S.

(5,127)

(8,007)

(1,243)

Deferred, State

2,043

3,073

331

Deferred, Total

(15,688)

(9,456)

28,340

Total provision for income taxes

$ 26,595

$ 41,013

$ 28,383

$ 20,878

$ 23,811

$ 15,873

$ 33,780

$ (15,159)

$ 116,868

$ 58,304

$ 16,022

[1]

Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.

[2]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[3]

Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.

[4]

Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.

[5]

Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.

[6]

Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.

[7]

Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.

[8]

Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[9]

Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[10]

Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[11]

Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																	12 Months Ended
	Dec. 31, 2020		Sep. 27, 2020	[2],[3]	Jun. 28, 2020	[2],[4]	Mar. 29, 2020	[5]	Dec. 31, 2019		Sep. 30, 2019	[9]	Jun. 30, 2019	[10]	Mar. 31, 2019	[11]	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Total (benefit) provision for income taxes	$ 26,595	[1],[2]	$ 41,013		$ 28,383		$ 20,878		$ 23,811	[6],[7],[8]	$ 15,873		$ 33,780		$ (15,159)			$ 116,868	$ 58,304	$ 16,022
Effective tax rate																		13.00%	11.10%	3.40%
Provisional amount of additional income tax expense																	$ 49,500				$ 186,000
Transition tax on mandatory deemed repatriation of foreign earnings																				$ 51,700	161,000
Expense (benefit) associated with impact of correlative adjustments on tax positions																				2,200
Tax savings due to the tax holiday																		$ 29,900	$ 15,100	$ 11,900
Tax savings due to the tax holiday, per share																		$ 0.16	$ 0.08	$ 0.06
Tax holiday expiration date																		December 31, 2025
Valuation allowance includes net deferred tax assets	84,962								77,177									$ 84,962	$ 77,177
Tax credit carryforwards, approximately																					116,300
Tax credits carryforwards	87,595								79,480									87,595	79,480
Reduction in unrecognized tax benefits	17,903								21,180								$ 43,395	17,903	21,180	$ 43,395	36,263
Unrecognized tax benefits, if recognized would impact effective tax rate	12,000																	12,000
Unrecognized tax benefits, if recognized would impact deferred taxes	5,900																	5,900
Accrued interest and penalties	1,200								$ 1,400									1,200	1,400
Interest and penalties related to income tax, expense (benefit)																		200	1,100	$ 100
Expense related to remeasurement of deferred tax assets and liabilities																		33,600
Possible Lapse Of Statutes Of Limitations [Member]
Income Taxes [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	1,600																	1,600
InterCompany Cost Sharing Arrangement [Member]
Income Taxes [Line Items]
Total (benefit) provision for income taxes																		2,300	$ 6,300
United States
Income Taxes [Line Items]
Tax credits carryforwards, business																					$ 1,900
Tax credit carryforward, expiration date																					2028
State and Local Jurisdiction
Income Taxes [Line Items]
Provisional amount of additional income tax expense																					$ 186,000
Expense (benefit) associated with impact of correlative adjustments on tax positions																					10,300
Tax credits carryforwards																					$ 114,300
Reduction in unrecognized tax benefits	$ 17,900																	$ 17,900
State and Local Jurisdiction | Earliest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																					2021
State and Local Jurisdiction | Latest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																					2040
State and Local Jurisdiction | Do Not Expire
Income Taxes [Line Items]
Tax credits carryforwards																					$ 63,800
[1]	Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[3]	Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.
[4]	Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.
[5]	Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.
[6]	Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.
[7]	Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.
[8]	Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[9]	Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[10]	Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[11]	Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

Schedule of Reconciliation of E

Schedule of Reconciliation of Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
U.S. statutory federal tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal tax benefit	0.30%	0.50%	0.10%
U.S. global intangible low-taxed income	5.70%	6.20%	0.30%
Foreign taxes	(5.60%)	(4.00%)	(2.00%)
Foreign tax credits	(4.80%)	(5.90%)	(2.20%)
U.S. foreign derived intangible income	(2.20%)	(2.60%)	(1.80%)
U.S. research and development credit	(1.30%)	(1.80%)	(2.20%)
Equity compensation	(0.60%)	(0.70%)	(1.20%)
Uncertain tax positions	(0.10%)	(4.30%)	1.00%
U.S. transition tax		1.90%	(10.50%)
Impact of rate change on deferred taxes			0.30%
Other, net	0.60%	0.80%	0.60%
Effective tax rate, Total	13.00%	11.10%	3.40%

Schedule of Components of Defer

Schedule of Components of Deferred Tax Assets Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Line Items]
Tax credits	$ 87,595	$ 79,480
Accruals	33,156	25,424
Pension liabilities	28,348	24,459
Inventory valuations	18,427	18,572
Lease liability	12,627	13,093
Deferred revenue	9,235	7,622
Equity compensation	6,543	7,042
Vacation accrual	5,890	4,768
Investment impairment	3,292	3,292
Net operating loss carryforwards	1,823	2,705
Other	626	187
Gross deferred tax assets	207,562	186,644
Less: valuation allowance	(84,962)	(77,177)
Total deferred tax assets	122,600	109,467
Depreciation	(14,525)	(18,238)
Intangible assets	(12,726)	(16,705)
Right of use assets	(10,688)	(11,197)
Contingent consideration	(3,515)
Marketable securities	(3,344)	(1,601)
Other	(710)	(611)
Total deferred tax liabilities	(45,508)	(48,352)
Net deferred assets	$ 77,092	$ 61,115

Summary of Operating Loss Carry

Summary of Operating Loss Carryforwards (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	$ 17,449
Foreign Operating Loss Carryforwards		$ 3,991
2021
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	333
2022
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	2,203
2023
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	3,368
2024
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	812
2025
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	191
2026-2030
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	7,452
2031-2035
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	2,147
Foreign Operating Loss Carryforwards		68
Beyond 2035
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	73
Non-Expiring
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	$ 870
Foreign Operating Loss Carryforwards		$ 3,923

Schedule of Unrecognized Tax Be

Schedule of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Beginning balance, as of January 1	$ 21,180	$ 43,395	$ 36,263
Tax positions for current year, Additions	1,082	1,322	4,716
Tax positions for prior years, Additions	66	8,043	2,626
Tax positions for prior years, Reductions	(2,989)	(31,397)	(153)
Expiration of statutes, Reductions	(1,436)	(183)	(57)
Ending balance as of December 31	$ 17,903	$ 21,180	$ 43,395

Operating Segment, Geographic_3

Operating Segment, Geographic and Significant Customer Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020Segment	Dec. 31, 2019Customer	Dec. 31, 2018Customer
Segment Reporting Information [Line Items]
Operating segments | Segment	4
Number of customer accounted for more than ten percent of consolidated revenue | Customer		0	0
Consolidated Revenue
Segment Reporting Information [Line Items]
Concentration risk, percentage		10.00%	10.00%
Semiconductor Test | Consolidated Revenue | Customer Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage	25.00%	10.00%	13.00%
Semiconductor Test | Customer 1 | Consolidated Revenue | Revenue from Rights Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage		15.00%
Semiconductor Test | Customer 1 | Consolidated Revenue | Revenue from Rights Concentration Risk | Series of Customer [Member]
Segment Reporting Information [Line Items]
Concentration risk, percentage	3.00%	11.00%

Schedule of Segment Information

Schedule of Segment Information (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	[1],[2]	$ 3,121,469	$ 2,294,965	$ 2,100,802
Income (loss) before taxes		901,015	525,772	467,801
Total assets		3,652,346	2,787,014	2,706,606
Property additions		184,977	134,642	114,379
Depreciation and amortization expense		126,743	120,655	113,224
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		2,259,597	1,552,571	1,492,417
Income (loss) before taxes		739,695	416,973	397,645
Total assets		1,070,378	784,808	669,452
Property additions		168,055	112,145	94,496
Depreciation and amortization expense		64,998	59,197	58,095
System Test
Segment Reporting Information [Line Items]
Revenues	[1]	409,729	287,455	216,132
Income (loss) before taxes		152,092	93,543	48,857
Total assets		138,295	131,428	88,098
Property additions		3,092	3,059	3,469
Depreciation and amortization expense		3,426	5,518	6,430
Industrial Automation
Segment Reporting Information [Line Items]
Revenues		279,731	298,139	261,452
Income (loss) before taxes		(24,019)	(5,916)	7,670
Total assets		712,936	671,559	607,502
Property additions		8,899	9,076	11,188
Depreciation and amortization expense		36,242	40,904	36,755
Wireless Test
Segment Reporting Information [Line Items]
Revenues	[1]	173,016	157,315	132,006
Income (loss) before taxes		41,950	35,585	29,052
Total assets		106,273	97,299	77,570
Property additions		4,931	10,362	5,226
Depreciation and amortization expense		6,258	5,365	5,328
Corporate And Others [Member]
Segment Reporting Information [Line Items]
Revenues		(604)	(515)	(1,205)
Income (loss) before taxes		(8,703)	(14,413)	(15,423)
Total assets		1,624,464	1,101,920	1,263,984
Depreciation and amortization expense		$ 15,819	$ 9,671	$ 6,616
[1]	Includes $10.0 million, $8.4 million and $12.0 million in 2020, 2019 and 2018, respectively, for leases of Teradyne’s systems recognized outside of ASC 606: “Revenue from Contracts with Customers.”
[2]	Revenues attributable to a country are based on location of customer site.

Schedule of Segment Reporting I

Schedule of Segment Reporting Information by Segment Charges (Detail) - USD ($) $ in Thousands	3 Months Ended																			12 Months Ended
	Dec. 31, 2020	[1],[2]	Sep. 30, 2020	Sep. 27, 2020	[2],[3]	Jun. 30, 2020	Jun. 28, 2020	[2],[4]	Mar. 31, 2020	Mar. 29, 2020	[5]	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Acquisition related costs			$ 500			$ 3,100			$ 1,400			$ 200		$ 500		$ 500		$ 1,300
Restructuring and other-employee severance	$ (15,117)			$ (27,701)			$ 37,222			$ (7,606)		(2,088)	[6],[7],[8]	(6,500)	[9]	(10,404)	[10]	5,112	[11]	$ (13,202)	$ (13,880)	$ 15,232
Contingent consideration adjustment																				(23,271)	(19,257)	987
Investment impairment												15,000									15,000
Universal Robots (UR)
Segment Reporting Information [Line Items]
Contingent consideration adjustment			$ 27,200			$ 29,900			$ 10,000					$ 7,800		$ 11,700		$ 3,000			3,800
Mobile Industrial Robots (MiR)
Segment Reporting Information [Line Items]
Contingent consideration adjustment												$ 5,800
Semiconductor Test
Segment Reporting Information [Line Items]
Acquisition related costs																				2,500	2,500
Cost of revenues-inventory charge																					1,277	8,429
Restructuring and other-employee severance																				11,013
Contingent consideration adjustment																				3,500
Contract termination settlement fee																				4,000
Semiconductor Test | Severance And Benefits
Segment Reporting Information [Line Items]
Restructuring and other-employee severance																					8,731	6,822
Industrial Automation
Segment Reporting Information [Line Items]
Acquisition related costs																				985	741	1,163
Cost of revenues-inventory charge																				887	2,000	1,175
Restructuring and other-employee severance																				1,584	796
Industrial Automation | Restructuring and other
Segment Reporting Information [Line Items]
Acquisition related costs																				1,728	1,765
Industrial Automation | Severance And Benefits
Segment Reporting Information [Line Items]
Restructuring and other-employee severance																						3,422
System Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge																				834	508	680
Wireless Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge																				4,800	4,005	2,565
Corporate And Eliminations
Segment Reporting Information [Line Items]
Selling and administrative – equity modification charge																				766	2,108
Corporate And Eliminations | Restructuring and other
Segment Reporting Information [Line Items]
Investment impairment																					15,000
Corporate And Eliminations | Universal Robots (UR) | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment																						(16,679)
Corporate And Eliminations | Mobile Industrial Robots (MiR) | Restructuring and other
Segment Reporting Information [Line Items]
Restructuring and other-lease impairment																				(3,546)	(22,199)	$ 17,666
Contingent consideration adjustment																				$ (19,724)	$ 2,976
[1]	Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[3]	Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.
[4]	Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.
[5]	Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.
[6]	Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.
[7]	Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.
[8]	Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[9]	Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[10]	Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[11]	Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

Schedule of Revenues by Country

Schedule of Revenues by Country (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[1],[2]	$ 3,121,469	$ 2,294,965	$ 2,100,802
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	465,722	514,327	348,942
TAIWAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	1,178,068	485,681	516,322
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	321,674	333,059	282,869
KOREA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	391,571	239,504	163,224
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	205,587	219,015	223,207
JAPAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	143,983	175,322	158,281
THAILAND
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	138,787	87,503	59,184
SINGAPORE
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	76,460	84,111	108,618
MALAYSIA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	56,096	58,200	122,797
PHILIPPINES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	68,887	54,560	77,996
Rest Of The World
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from unaffiliated customers	[2]	$ 74,634	$ 43,683	$ 39,362
[1]	Includes $10.0 million, $8.4 million and $12.0 million in 2020, 2019 and 2018, respectively, for leases of Teradyne’s systems recognized outside of ASC 606: “Revenue from Contracts with Customers.”
[2]	Revenues attributable to a country are based on location of customer site.

Schedule of Long-Lived Assets b

Schedule of Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		$ 449,369	$ 377,755
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		291,234	252,812
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	[1]	$ 158,135	$ 124,943
[1]	As of December 31, 2020 and 2019, long-lived assets attributable to Singapore were $62.5 million and $35.2 million, respectively.

Schedule of Long-Lived Assets_2

Schedule of Long-Lived Assets by Geographic Area (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 449,369	$ 377,755
SINGAPORE
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 62,500	$ 35,200

Stock Repurchase Program - Addi

Stock Repurchase Program - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jan. 01, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2021	Jan. 01, 2020	Jan. 31, 2019
Stock Repurchase Programs [Line Items]
Cumulative repurchases, shares	10.9	1.5	32.5	21.6	2	1,000
Cumulative repurchases, value		$ 88.5	$ 1,323	$ 823.5	$ 600
Common stock average price	$ 45.89	$ 58.33	$ 40.68	$ 38.06
Maximum
Stock Repurchase Programs [Line Items]
Cumulative repurchases, value							$ 500

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - $ / shares	1 Months Ended
	Jan. 31, 2021	Jan. 31, 2020
Subsequent Event [Line Items]
Cash Dividends payable, amount per share		$ 0.10
Cash Dividends payable, date to be paid		Mar. 19, 2021
Cash Dividends payable, record date	Feb. 19, 2021

Consolidated Quarterly Statemen

Consolidated Quarterly Statements of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																		12 Months Ended
	Dec. 31, 2020	[1],[2]	Sep. 27, 2020	[2],[3]	Jun. 28, 2020	[2],[4]	Mar. 31, 2020	[5]	Mar. 29, 2020	[6]	Dec. 31, 2019	[7],[8],[9]	Sep. 30, 2019	[10]	Jun. 30, 2019	[11]	Mar. 31, 2019	[5]	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information [Line Items]
Total revenues	$ 758,968		$ 819,484		$ 838,661		$ 494,099		$ 704,355		$ 654,650		$ 582,038		$ 564,178
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	309,179		360,556		367,188				298,805		271,412		237,000		240,260		$ 206,464		$ 1,335,728	$ 955,136	$ 880,408
Gross profit	449,789		458,928		471,473				405,550		383,238		345,038		323,918		287,635		1,785,741	1,339,829	1,220,394
Selling and administrative	124,279		115,840		113,259				111,388		117,092		109,166		108,811		102,013		464,769	437,084	390,669
Engineering and development	100,795		94,909		94,102				85,159		86,794		77,804		81,434		76,791		374,964	322,824	301,505
Acquired intangible assets amortization	5,752		6,219		8,941				9,891		9,784		9,647		10,083		10,634		30,803	40,147	39,191
Restructuring and other	(15,117)		(27,701)		37,222				(7,606)		(2,088)		(6,500)		(10,404)		5,112		(13,202)	(13,880)	15,232
Total operating expenses	215,709		189,267		253,524				198,832		211,582		190,117		189,924		194,550		857,334	786,175	746,597
Income from operations	234,080		269,661		217,949				206,718		171,656		154,921		133,994		93,085		928,407	553,654	473,797
Interest income	(793)		(1,071)		(1,368)				(2,751)		(3,185)		(4,433)		(4,384)		(4,989)		(5,982)	(16,990)	(20,458)
Interest expense	6,351		6,237		6,043				5,551		5,441		5,463		5,800		5,520		24,182	22,224	21,780
Other (income) expense, net	5,597		764		(4,017)				6,849		20,514		2,158		1,401		(1,425)		9,192	22,648	4,674
Income before income taxes	222,925		263,731		217,291				197,069		148,886		151,733		131,177		93,979		901,015	525,772	467,801
Income tax provision (benefit)	26,595		41,013		28,383				20,878		23,811		15,873		33,780		(15,159)		116,868	58,304	16,022
Net income	$ 196,330		$ 222,718		$ 188,908				$ 176,191		$ 125,075		$ 135,860		$ 97,397		$ 109,138		$ 784,147	$ 467,468	$ 451,779
Net income per common share—basic	$ 1.18		$ 1.34		$ 1.14				$ 1.06		$ 0.75		$ 0.80		$ 0.57		$ 0.63		$ 4.72	$ 2.74	$ 2.41
Net income per common share—diluted	1.05		1.21		1.05				0.97		0.69		0.75		0.55		0.62		$ 4.28	$ 2.60	$ 2.35
Cash dividend declared per common share	$ 0.10		$ 0.10		$ 0.10				$ 0.10		$ 0.09		$ 0.09		$ 0.09		$ 0.09
Product [Member]
Quarterly Financial Information [Line Items]
Total revenues	$ 647,625		$ 697,745		$ 734,630		393,442		$ 610,906		$ 548,552		$ 488,170		$ 457,511
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	274,574		300,174		322,732				259,996		226,184		197,196		193,299		$ 165,368		$ 1,157,476	$ 782,047	$ 727,138
Service [Member]
Quarterly Financial Information [Line Items]
Total revenues	111,343		121,739		104,031		$ 100,657		93,449		106,098		93,868		106,667
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	$ 34,605		$ 60,382		$ 44,456				$ 38,809		$ 45,228		$ 39,804		$ 46,961		$ 41,096		$ 178,252	$ 173,089	$ 153,270
[1]	Restructuring and other includes a $15.3 million gain for the decrease in the fair value adjustment to the AutoGuide acquisition contingent consideration liability, and a $0.9 million gain for the decrease in acquisition related compensation liability, partially offset by $1.1 million of employee severance charges primarily in Industrial Automation.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(0.1) million, $2.7 million, $7.7 million for the second, third and fourth quarter in 2020, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[3]	Restructuring and other includes a $27.2 million gain for the decrease in the fair value of AutoGuide contingent consideration liability, and a $1.1 million gain for the decrease in acquisition related compensation liability, partially offset by $0.5 million recorded for employee severance charges primarily in Industrial Automation.
[4]	Restructuring and other includes a $29.9 million charge for the increase in the fair value of the AutoGuide contingent consideration liability, a $4.0 million contract termination settlement charge, $3.1 million of acquisition related compensation and expense and $0.8 million of other expenses, partially offset by a $0.6 million gain for the decrease in the fair value of MiR contingent consideration liability.
[5]	Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.
[6]	Restructuring and other includes a $10.0 million gain for the decrease in the fair value of the AutoGuide and MiR contingent consideration liabilities, partially offset by $1.4 million of acquisition related compensation and expenses and $0.7 million of severance charges related to headcount reductions primarily in Industrial Automation and Semiconductor Test.
[7]	Other (income) expense, net includes a $15.0 million charge for the impairment of the investment in RealWear.
[8]	Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.
[9]	Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.
[10]	Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.
[11]	Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

Consolidated Quarterly Statem_2

Consolidated Quarterly Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment									$ (23,271)	$ (19,257)	$ 987
Impairment of fixed assets and other expenses			$ 800
Severance benefit and charges	$ 1,100	$ 1,100		$ 700	$ 500	$ 800	$ 800	$ 800
Acquisition related expense and compensation		500	3,100	1,400	200	500	500	1,300
Pension and post retirement net actuarial (gains) losses	7,700	2,700	100		7,700					(29,000)
Investment impairment					15,000					15,000
Universal Robots (UR)
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment		$ 27,200	29,900	$ 10,000		$ 7,800	$ 11,700	$ 3,000		3,800
Mobile Industrial Robots (MiR)
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment					5,800
Autoguide LLC
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment	15,300		600		$ 3,000					$ 3,000
Acquisition related expense and compensation	$ 900
Contract termination settlement fee			$ 4,000

Valuation and Qualifying Acco_2

Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 1,736	$ 1,673	$ 2,219
Additions Charged to Cost and Expenses	356	87	0
Other	32	28	20
Deductions	90	52	566
Balance at End of Period	2,034	1,736	1,673
Inventory Reserve
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	103,556	100,779	102,896
Additions Charged to Cost and Expenses	17,534	15,244	11,242
Other	(521)	(85)	368
Deductions	9,982	12,382	13,727
Balance at End of Period	110,587	103,556	100,779
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	77,177	69,852	63,919
Additions Charged to Cost and Expenses	7,785	7,325	6,333
Other	0		0
Deductions	0		400
Balance at End of Period	$ 84,962	$ 77,177	$ 69,852